Simultaneous transesophageal atrial pacing and transesophageal two-dimensional echocardiography: a new method of stress echocardiography

Detection of coronary stenoses by stress echocardiography using a previously implanted pacemaker for ventricular pacing: preliminary report of a new method

BACKGROUND

The number of patients with pacemakers has been increasing and a large number of them will present with chest pain or symptoms suggesting angina pectoris. Myocardial ischemia and presence of coronary artery disease are difficult to detect and assess by noninvasive methods in patients with a pacemaker; the electrocardiogram (ECG) at rest and during exercise is usually very difficult to analyze in terms of ischemia or even presence of an acute myocardial infarction.

HYPOTHESIS

To detect significant coronary stenosis in patients with previously implanted pacemakers, we tested a new stress echocardiography method using incremental ventricular pacing by already implanted pacemakers.

METHODS

We studied prospectively 25 consecutive patients who underwent stress echocardiography with increasing ventricular pacing up to either 85% of the age-predicted maximal heart rate or chest pain. Positive tests were defined by new hypokinesia or worsening of a preexisting alteration in wall motion in at least two adjacent territories. All patients underwent coronary angiograms to define the presence and severity of coronary stenoses.

RESULTS

Among the 25 tests, 11 (44%) were stopped for chest pain. 1 (4%) for moderate discomfort, 1 (4%) for a drop in blood pressure, and the target pacing rate was achieved in the tests of the remaining 12 patients (48%). There were no complications. Thirteen patients had significant stenoses. In 10 cases, stress echocardiography was a true positive test with respect to coronary angiography. There were 11 true negative, 1 false positive, and 3 false negative tests. The sensitivity was 77%, specificity was 90%, the positive predictive value was 91%, and the negative predictive value 79%. The accuracy was 84%.

CONCLUSIONS

This new stress echocardiography method appears feasible, easy, safe, and effective for detection of significant coronary stenoses in patients with pacemakers.

Ischemia induced by transesophageal atrial pacing stress echocardiography predicts long-term mortality

OBJECTIVES

It was the aim of this study to investigate the long-term value of transesophageal atrial pacing in predicting death in patients with known or suspected coronary artery disease.

BACKGROUND

Exercise, dobutamine and dipyridamole stress echocardiography are all effective in predicting cardiac death. Transesophageal atrial pacing stress echocardiography (TAPSE) is a safe alternative to pharmacologic tests, but no information is available on prognosis with TAPSE.

METHODS

One thousand and ten TAPSE were performed in 975 consecutive patients. TAPSE was feasible in 970 tests (96%); after exclusion of the 35 patients with more than 1 TAPSE and those 42 lost at follow-up (mean 4.5 +/- 3.7 years, median 6 years), the final population consisted of 857 patients (675 males, 58 +/- 9 years old). The Cox model was used to analyze the association of clinical, resting and TAPSE variables with cardiac death.

RESULTS

TAPSE was abnormal in 281 (32%) patients. There were 46 cardiac-related deaths (5%), 25 among the 281 patients with an abnormal test (8.9%) and 21 among the 576 patients with a normal test (3.6%). The predictors of cardiac death were age, previous revascularization, resting wall motion score index and its variation during TAPSE. Abnormal TAPSE significantly increases the value of models predicting cardiac death. Moreover, cardiac mortality increased progressively with the extent of the induced ischemia.

CONCLUSIONS

TAPSE is a useful tool in predicting death in patients with known or suspected coronary artery disease and might be considered an alternative to pharmacologic stressors.

Termination of atrial flutter by directed transesophageal atrial pacing during transesophageal echocardiography

INTRODUCTION

The purpose of this study was to evaluate termination of atrial flutter (AFL) by directed rapid transesophageal atrial pacing (TAP) with and without simultaneous transesophageal echocardiography (TEE) performed using a novel TEE tube electrode.

MATERIALS AND METHODS, AND RESULTS

A total of 16 AFL patients (age 63+/-12 years; 13 males) with mean AFL cycle length of 224+/-24 ms (n=12) and mean ventricular cycle length of 448+/-47 ms (n=12) were analyzed using either an esophageal TO electrode (n=10) or a novel TEE tube electrode consisting of a tube with four hemispherical electrodes that is pulled over the echo probe (n=6). AFL could be terminated by directed rapid TAP using an esophageal TO electrode, leading to induction of atrial fibrillation (AF) (n=6), induction of AF and spontaneous conversion to sinus rhythm (SR) (n=3), and with conversion to SR (n=1). AFL could also be terminated by directed rapid TAP using the TEE tube electrode, with induction of AF (n=3) or induction of AF and spontaneous conversion to SR (n=3).

CONCLUSION

AFL can be terminated by directed rapid TAP with hemispherical electrodes with and without simultaneous TEE. TAP with the directed TEE tube electrode is a safe, simple, and useful method for terminating AFL.

Systematic overview and clinical applications of pacing atrial stress echocardiography

Pacing atrial stress echocardiography (PASE) has been studied over the past 3 decades for the evaluation of myocardial ischemia. Published studies suggest that PASE may be used as an alternative to exercise or pharmacologic stress imaging. The recent introduction of improved pacing electrodes, together with use of accelerated and shortened pacing protocols and improvements in transthoracic echocardiographic imaging techniques, makes PASE an appealing stress imaging method. A critical analysis of the diagnostic accuracy of PASE shows equivalence with other imaging stress modalities. PASE has been found to be highly feasible and accurate technique that may expedite the diagnosis and risk stratification of patients with coronary artery disease. This review addresses the history, hemodynamics, protocols, accuracy, clinical utility, and cost-effectiveness of PASE as well as elucidating its place among other stress modalities.

Pacemaker stress echocardiography predicts cardiac events in patients with permanent pacemaker

PURPOSE

Noninvasive pacemaker stress echocardiography is a newly introduced method for the diagnosis of coronary artery disease in patients with a permanent pacemaker. The prognostic value of pacemaker stress echocardiography has not been studied.

SUBJECTS AND METHODS

We studied 136 patients (mean age 64+/-12 years) with a permanent pacemaker who underwent pacemaker stress echocardiography for evaluation of coronary artery disease. All patients underwent pacemaker stress echocardiography by external programming (pacing heart rate up to ischemia or target heart rate).

RESULTS

Thirty-one patients (23%) had normal study results. Ischemia was detected in 75 patients (55%). During a mean follow-up of 3.5+/-2.4 years, 35 deaths (26%) (20 the result of cardiac causes) and 2 nonfatal myocardial infarctions (1%) occurred. The annual cardiac death rate was 1.3% in patients without ischemia and 4.6% in patients with ischemia (P=.01). The annual all-cause mortality rate was 3.1% in patients without ischemia and 7% in patients with ischemia (P=.004). The presence of ischemia during pacemaker stress echocardiography was the strongest independent predictor of cardiac death (hazard ratio 4.1, confidence interval 1.2-14.5) and all-cause mortality (hazard ratio 2.7, confidence interval 1.2-6.0) in a multivariable model.

CONCLUSION

Myocardial ischemia during pacemaker stress echocardiography is an independent predictor of cardiac death and all-cause mortality in patients with a permanent pacemaker.

Head-to-head comparison of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia in an animal model of coronary artery stenosis

To compare the sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia we produced a physiologically significant stenosis in the left circumflex artery of 14 open-chest dogs (range: 50 to 89% reduction in luminal diameter). In each study, dobutamine (5 to 40 microg kg(-1) min(-1) in 3-min stages) and pacing (20 bpm increments, each 2 min, up to 260 bpm) were performed randomly, and then followed by dipyridamole (up to 0.84 mg/kg over 10 min). The positivity of stress echocardiography tests was quantitatively determined by a significant (P<0.05) reduction of or failure to increase absolute and percent systolic wall thickening in the stenotic artery supplied wall, as compared to the opposite wall (areas related to the left anterior descending artery). Systolic and diastolic frozen images were analyzed off-line by two blinded observers in the control and stress conditions. The results showed that 1) the sensitivity of dobutamine, dipyridamole and pacing stress tests was 57, 57 and 36%, respectively; 2) in animals with positive tests, the mean percent change of wall thickening in left ventricular ischemic segments was larger in the pacing (-19 +/- 11%) and dipyridamole (-18 +/- 16%) tests as compared to dobutamine (-9 +/- 6%) (P = 0.05), but a similar mean reduction of wall thickening was observed when this variable was normalized to a control left ventricular segment (area related to the left anterior descending artery) (pacing: -16 +/- 7%; dipyridamole: -25 +/- 16%; dobutamine: -26 +/- 10%; not significant), and 3) a significant correlation was observed between magnitude of coronary stenosis and left ventricular segmental dysfunction induced by ischemia in dogs submitted to positive stress tests. We conclude that the dobutamine and dipyridamole stress tests showed identical sensitivities for the detection of myocardial ischemia in this one-vessel disease animal model with a wide range of left circumflex artery stenosis. The pacing stress test was less sensitive, but the difference was not statistically significant. The magnitude of segmental left ventricular dysfunction induced by ischemia was similar in all stress tests evaluated.

Pacing stress echocardiography: an alternative to pharmacologic stress testing

OBJECTIVES

We sought to evaluate the diagnostic accuracy and feasibility of bedside pacing stress echocardiography (PASE) as a potential substitute for pharmacologic stress echocardiography in patients admitted to the hospital with new-onset chest pain or worsening angina pectoris.

BACKGROUND

Accurate and rapid noninvasive identification and evaluation of the extent of coronary artery disease (CAD) is essential for optimal management of these patients.

METHODS

Bedside transthoracic stress echocardiography was performed in 54 consecutive patients admitted to a community hospital with new-onset chest pain, after acute myocardial infarction had been excluded. We used 10F transesophageal pacing catheters and a rapid and modified pacing protocol. The PASE results were validated in all patients by coronary angiography performed within 24 h of the test. Significant CAD was defined as > or =75% stenosis in at least one major epicardial coronary artery.

RESULTS

The sensitivity of PASE for identifying patients with significant CAD was 95%, specificity was 87% and accuracy was 92%. The extent of significant CAD (single- or multivessel disease) was highly concordant with coronary angiography (kappa = 0.73, p<0.001). Pacing stress echocardiography was well tolerated, and only 4% of the patients had minor adverse events. The mean rate-pressure product at peak pacing was 22,313+/-5,357 beats/min per mm Hg, and heart rate >85% of the age-predicted target was achieved in 94% of patients. The average duration of the bedside PASE test, including image interpretation, was 38+/-6 min.

CONCLUSIONS

Bedside PASE is rapid, tolerable and accurate for identification of significant CAD in patients admitted to the hospital with new-onset chest pain or worsening angina pectoris.

Transesophageal echocardiographic (TEE) evaluation of ventricular function

Transesophageal echocardiography (TEE) provides excellent delineation of ventricular function in the ambulatory and critical settings. Major indications include the acutely ill patient with suboptimal images with other techniques and the intraoperative assessment of patients undergoing cardiac surgery and of cardiac patients undergoing noncardiac surgery. The methodology of quantification of ventricular function is quite accurate, though it has inherent limitations. Newer technologies, such as edge enhancement techniques, three-dimensional acquisition, and contrast agents, all have the potential to improve evaluation of ventricular function with TEE. Stress imaging with TEE is possible with dobutamine and with pacing techniques. This is sage and accurate, and it is indicated in patients, such as the morbidly obese, who are impossible to image by other methods.

[Complications of transesophageal echocardiography with dobutamine]

The transesophageal echocardiographic approach improves the diagnostic power of transthoracic stress echocardiography. However, it is a seminvasive test and its safety is not well established. Our objective was to compare the incidence of complications of transesophageal and transthoracic dobutamine echocardiography. We collected data from 63 patients with inadequate transthoracic window, who underwent transesophageal dobutamine echocardiography and were compared with 100 patients in whom the transthoracic approach was diagnostic. Baseline blood pressure and heart rate were higher in the first group. There were no differences in those parameters at the end of the test. Neither were atropine administration and side effects more frequent in any of the groups. There were no cases of ventricular fibrillation, ventricular tachycardia, acute myocardial infarction, intractable angina or intolerance to the probe. Side effects were equally present in both groups. Transesophageal dobutamine stress echocardiography is a safe test that can be used in patients with coronary artery disease and poor transthoracic window.

Transthoracic stress echocardiography with transesophageal atrial pacing for bedside evaluation of inducible myocardial ischemia in patients with new-onset chest pain

To date, there are no data on the feasibility and accuracy of bedside pacing stress echocardiography in patients admitted to the hospital with new-onset chest pain or unstable angina. We evaluated the feasibility of pacing stress echocardiography and examined its correlation with myocardial perfusion stress scintigraphy (rest thallium-201/stress technetium-99m sestamibi dual-isotope myocardial perfusion single-photon emission computerized tomography) performed within 24 hours of the pacing stress echocardiography test. We studied 70 consecutive patients after acute myocardial infarction had been excluded. The bedside pacing stress echocardiography test was performed with 10Fr transesophageal pacing catheters. We found pacing stress echocardiography to be feasible and safe (3% minor adverse event rate) at the patients' bedside. Target heart rate of >85% of the age-predicted heart rate was achieved in 96% of patients, and the mean rate-pressure product was 22,644 +/- 4,520 beats/min/mm Hg. The mean duration of the bedside pacing stress echocardiography test including technical preparations and image interpretation was 41 +/- 7 minutes. Pacing stress echocardiography and myocardial perfusion stress scintigraphy correlated well for identification or exclusion of inducible myocardial ischemia in 63 of 70 patients (90%) (kappa 0.81, p <0.001). The extent of inducible myocardial ischemia by vascular territories correlated with myocardial perfusion stress scintigraphy in 52 of 70 patients (74%) (kappa 0.6, p <0.001). We conclude that bedside pacing stress echocardiography is feasible and safe, and highly correlates with myocardial perfusion stress scintigraphy for identifying inducible myocardial ischemia in patients with new onset of chest pain or unstable angina.

Non-contrast second harmonic imaging improves interobserver agreement and accuracy of dobutamine stress echocardiography in patients with impaired image quality

OBJECTIVE

To examine the influence of second harmonic imaging during dobutamine echocardiography on regional endocardial visibility, interobserver agreement in the interpretation of wall motion abnormalities, and diagnostic accuracy in patients with reduced image quality.

DESIGN

Blinded comparison.

SETTING

Tertiary care centre.

PATIENTS

103 consecutive patients with suspected coronary artery disease and impaired transthoracic image quality (>/= 2 segments with poor endocardial delineation).

METHODS

Fundamental and second harmonic imaging were performed at each stage of a dobutamine stress echocardiography. Coronary angiography was undertaken within three weeks of dobutamine echocardiography in 75 patients.

MAIN OUTCOME MEASURES

Evaluation of regional endocardial visibility (scoring from 0 = poor to 2 = good) and of segmental wall motion abnormalities for both modalities separately. A second blinded examiner analysed 70 studies to determine interobserver agreement.

RESULTS

Mean (SD) visibility score for all segments was 1.2 (0.4) using fundamental imaging and 1.7 (0.2) using second harmonic imaging at rest (p < 0.001), and 1.1 (0.4) v 1.6 (0.3), respectively, at peak dobutamine dose (p < 0.001). The average number of segments with poor endocardial visibility was lower for second harmonic than for fundamental imaging (0.6 (1.1) v 3.8 (2.6) at rest, p < 0.001; 0.9 (1.3) v 4.3 (2.9) at peak dose, p < 0.001). Improvement was most pronounced in all lateral and anterior segments. The kappa value for identical study interpretation increased from 0. 40 to 0.69 (p < 0.05). Sensitivity for the diagnosis of coronary artery disease was 64% using fundamental imaging versus 92% using harmonic imaging (p < 0.001), while specificity remained unchanged at 75% for both imaging modalities.

CONCLUSIONS

Second harmonic imaging enhances endocardial visibility during dobutamine echocardiography. Consequently, interobserver agreement on stress echocardiography interpretation and diagnostic accuracy are significantly improved compared to fundamental imaging. Thus, in difficult to image patients, dobutamine echocardiography should be performed using second harmonic imaging.

Transesophageal echocardiography with stress for the evaluation of patients with coronary artery disease

Echocardiography permits a comprehensive assessment of resting regional and global left ventricular function, the presence and extent of inducible myocardial ischemia, and the identification of myocardial viability. Accordingly, stress echocardiography has become a valuable tool for the evaluation of patient with known or suspected coronary artery disease. In some patients however, a suboptimal transthoracic echocardiogram may limit the performance of interpretation of the test. Transesophageal echocardiography in combination with stress has been recently used for the evaluation of patients with coronary artery disease. This technique is semi-invasive, more time-consuming, and requires a greater degree of expertise on the part of the personnel assisting with the test. In general, complications and side-effects are self-limited and rarely affect the diagnostic accuracy of the test. Based on its ability to provide high quality images, transesophageal stress echocardiography should be considered in patients who have suboptimal transthoracic ultrasound window for the quantitative assessment of myocardial wall-thickening in clinical investigations of ischemic heart disease.

Nonexercise stress transthoracic echocardiography: transesophageal atrial pacing versus dobutamine stress

OBJECTIVES

To compare transesophageal atrial pacing stress echocardiography with dobutamine stress echocardiography for feasibility, safety, duration, patient acceptance and concordance in inducing wall motion abnormalities.

BACKGROUND

Transesophageal atrial pacing is an effective method of increasing heart rate and has been used in the assessment of coronary artery disease.

METHODS

Both tests were performed in sequence on the same patients in random order. Transesophageal atrial pacing stress echocardiography began at a heart rate of 10 beats/min above the baseline value and was increased by 20 beats/min every two min until 85% of the age-predicted maximum heart rate or another end point was reached. Dobutamine echocardiography was performed using three-min stages and a maximum dose of 40 microg/kg per min. Atropine (total dose < or =2 mg) was administered at the start of the 40 microg/kg per min stage if needed to augment heart rate or during pacing if Wenckebach heart block occurred.

RESULTS

Transesophageal atrial pacing stress echocardiography was feasible in 100 of 104 patients (96%); the duration (8.6+/-3.6 min) was significantly shorter than that of dobutamine stress echocardiography (15.1+/-3.9 min) (p = 0.0001). With transesophageal atrial pacing stress echocardiography, the recovery period was shorter, symptoms and dysrhythmias were fewer, hypertension and hypotension were less common and target heart rate was more frequently achieved. No complications occurred with either test. Patient acceptance was satisfactory. Agreement between results of both tests was good for segmental wall motion scoring with a 16-segment model, scores 1 to 5 (kappa: rest, 0.79; peak, 0.57) and test interpretation (normal, ischemia, infarction or resting wall motion abnormality with ischemia) (kappa: 0.77).

CONCLUSIONS

Transesophageal atrial pacing stress echocardiography is a feasible, well-tolerated alternative to dobutamine stress echocardiography. It can be performed rapidly and shows good agreement with dobutamine stress echocardiography in the induction of myocardial ischemia.

Transnasal Transesophageal Stress Echocardiography

Exercise echocardiography is a widely used modality for the noninvasive assessment of coronary artery disease. However, limitations exist inherent to the acquisition of transthoracic echocardiographic images. Although transesophageal echocardiography has been used during pacing or pharmacological stress, its use during exercise stress testing has not been clinically feasible due to the large probe size. Recently, a miniaturized transesophageal probe was developed, and we sought to test the feasibility of using this probe during graded treadmill exercise testing. Normal subjects were studied with transnasal echocardiography during upright treadmill exercise testing. The transnasal probe was passed in 13 of the 15 subjects. Excellent-quality monoplane two-dimensional echocardiographic images were obtained in all patients in the upright position. During exercise treadmill testing, high quality clinically useful echocardiographic images of the left ventricular short axis could be maintained. We conclude that transnasal transesophageal stress echocardiography may offer a new modality for the exercise assessment of ischemic heart disease.

Multiplane Transesophageal Echocardiography with Dobutamine in Patients with Biventricular Inferior Myocardial Infarction

The purpose of this study was to evaluate the alterations of ventricular wall movement in patients with acute posteroinferior myocardial infarction with extension to right cavities with multiplane transesophageal echocardiography (TEE), as well as the utility of dobutamine with this technique to analyze myocardial viability. Nine men with a mean age of 51 years fulfilled the inclusion criteria. Myocardial TEE was performed in all the men 72 hours after the acute event with long- and short-axis transgastric images of both ventricles under basal conditions and with dobutamine infusions of 5 and 10 µg/kg per minute. Results were compared with myocardial perfusion findings obtained with Tc-99m Sestamibi SPECT. Left ventricular myocardial viability was demonstrated in 28 of 45 altered segments with dobutamine stress myocardial TEE and Tc-99m Sestamibi SPECT. Right ventricular myocardial viability was identified in 27 of 30 altered segments with dobutamine stress myocardial TEE in transgastric short and long axes, and with Tc-99m Sestamibi SPECT in 23 of 25 segments only in short-axis images. Multiplane TEE provided excellent image resolution and better definition of endocardial and epicardial borders, which facilitated detailed evaluation of ventricular segmental wall movement. Infusion of low doses of dobutamine made it possible to identify viable tissue in both ventricles, and results were comparable to those of nuclear medicine.

[Elective noninvasive test in the diagnosis of coronary disease in the aged]

BACKGROUND AND PURPOSE

The purpose of this study was to determine the best noninvasive test to diagnose coronary artery disease in the elderly. PATTERNS AND METHODS: We conducted a study on 56 elderly patients (> 65 years) with chest pain and no previous history of coronary artery disease. They underwent exercise stress test, dipyridamole echocardiography (0.84 mg/kg), dobutamine echocardiography (up to a total dose of 40 microgram/kg/min and atropine when it was necessary), dobutamine MIBI-SPECT and coronary angiography.

RESULTS

Angiography detected significant coronary artery disease in 41 patients. All tests used in this study had a similar sensitivity (conclusive exercise stress test 87%, dipyridamole echocardiography 83%, dobutamine echocardiography 80% and MIBI-SPECT 87%; p = NS). Coronary angiography did not identify significant lesions in 15 patients. Specificity of conclusive exercise stress test, dipyridamole and dobutamine echocardiography was similar (75%, 100% and 93% respectively; p = NS). However, the specificity of stress echocardiography was higher than that of scintigraphy (100% vs 66%; p = 0.02 for dipyridamole echocardiography and 93% vs 66%; p = 0.07 for dobutamine echocardiography). Diagnostic accuracy of each test was similar.

CONCLUSIONS

Exercise stress test remains the non invasive diagnostic test of choice to detect coronary disease in the elderly. If this test is inconclusive, both stress echocardiography and isotopic studies are useful, although the specificity of stress echocardiography is higher than that of scintigraphy.

Acute hypovolemia may cause segmental wall motion abnormalities in the absence of myocardial ischemia

New segmental wall motion abnormalities (SWMA) detected by echocardiography are considered sensitive and specific markers of myocardial ischemia. However, we have observed new SWMA during pacing-induced reductions in left ventricular filling, which resolved immediately with cessation of the atrial pacing and simultaneous restoration of filling. Therefore, we designed this study to determine whether acute reduction in filling can induce new SWMA in the absence of ischemia. Institution of cardiopulmonary bypass was used as a clinical model of acute reduction in filling, and a beat-by-beat analysis of left ventricular contraction, filling, blood pressures, and electrocardiogram was performed when the drainage of blood to the cardiopulmonary bypass machine rapidly emptied the heart. Acute reduction in filling induced new SWMA in 4 of 38 study patients. All 4 patients had preexisting abnormalities of left ventricular contraction, but translocation of these preexisting SWMA did not explain the new SWMA, nor did myocardial ischemia. We conclude that acute reduction in left ventricular filling can cause new SWMA in the absence of ischemia. This finding limits the usefulness of new SWMA as a marker of ischemia in the presence of acute reduction in filling, such as that secondary to severe hypovolemia.

IMPLICATIONS

This study documented that acute reduction in cardiac filling can be associated with new systolic wall motion abnormalities detected by transesophageal echocardiography in the absence of documented myocardial ischemia. These findings indicate that segmental wall motion may not be a valid marker for ischemia in the setting of acute hypovolemia.

Rapid atrial pacing for detecting provokable demand ischemia in anesthetized patients

A stress test that can be performed intraoperatively might be valuable for cardiac risk stratification in patients needing urgent noncardiac surgery and for early evaluation of coronary reserve in patients undergoing aortocoronary bypass surgery. Therefore, we evaluated the sensitivity and safety of rapid atrial pacing combined with electrocardiography and transesophageal echocardiography for inducing and detecting provokable demand ischemia in 20 anesthetized patients with multivessel coronary artery disease. Rapid atrial pacing induced ST segment changes or new segmental wall motion abnormalities (SWMA), which were defined as evidence of induced ischemia in 15 of the 20 patients. Unexpectedly, the new SWMA normalized during the first beat after abrupt cessation of pacing in three patients who did not show any ST segment changes. Simultaneously, left ventricular preload was severely decreased during pacing and recovered to baseline immediately when pacing was abruptly discontinued. Rapid atrial pacing was safe in all patients, but the target heart rate could not be achieved because of heart block or arterial hypotension in 4 of the 20 patients. These findings raise the question of whether rapid atrial pacing is the most appropriate approach for inducing provokable demand ischemia in anesthetized patients. However, its potential usefulness for predicting adverse cardiac outcomes has not been evaluated and would require larger studies. In addition, the immediate normalization of new SWMA after abrupt cessation of pacing in some patients calls into question the validity of new SWMA as evidence of myocardial ischemia when left ventricular preload is severely decreased.

Investigation of the mechanism of chest pain in patients with angiographically normal coronary arteries using transesophageal dobutamine stress echocardiography

OBJECTIVES

The present study sought to determine whether myocardial contractile abnormalities accompany the development of chest pain in patients with normal coronary angiograms.

BACKGROUND

The mechanism of chest pain in patients with angina despite a normal coronary arteriogram is controversial. Although previous studies postulated the existence of coronary microvascular dysfunction, others failed to find evidence of myocardial ischemia, and recent studies have demonstrated abnormal cardiac sensitivity in these patients that can lead to chest pain on a nonischemic basis.

METHODS

Seventy patients (26 men and 44 women, mean age 49 +/- 10 years) with angina-like chest pain and angiographically normal coronary arteries underwent exercise treadmill testing, radionuclide angiography at rest and during exercise, thallium stress testing and transesophageal dobutamine stress echocardiography. The results of exercise treadmill testing and stress echocardiography were compared with those obtained in 26 normal control subjects (19 men and 7 women, mean age 56 +/- 7 years).

RESULTS

Abnormalities consistent with myocardial ischemia were noted in 31% of the patients during exercise treadmill testing, in 16% during exercise radionuclide angiography and in 18% during thallium stress testing. The findings of the radionuclide studies were not concordant with one another and were not related to the presence of repolarization changes during exercise testing. During infusion of dobutamine, chest pain developed in 59 patients (84%) and in none of the control subjects (p < 0.0001); repolarization changes occurred in 22 patients (34%) and in 2 control subjects (8%) (p < 0.04). None of the patients or the control subjects developed regional wall motion abnormalities with dobutamine. The quantitative myocardial contractile response to dobutamine was similar in patients and control subjects, with an 80% power to detect a 25% difference in systolic wall thickening at the maximal dose of dobutamine.

CONCLUSIONS

There was no agreement in the results of noninvasive tests in our patients. Despite the frequent provocation of chest pain and electrocardiographic abnormalities with dobutamine, the patients demonstrated a quantitatively normal myocardial contractile response without development of wall motion abnormalities. These observations strongly suggest that myocardial ischemia is not the cause of chest pain in patients with a normal coronary arteriogram.

Transesophageal dobutamine-atropine stress echocardiography: diagnostic accuracy for coronary stenosis detection and localization

Transesophageal echocardiography with dobutamine-atropine stress (TE-DASE) is a recently described technique for evaluation of coronary artery disease (CAD). We undertook this study prospectively to determine the feasibility, reliability and safety of this procedure in patients with known CAD and to evaluate its diagnostic accuracy for coronary stenoses of varying severity. Thirty-seven patients who underwent coronary arteriography (CART) and TE-DASE within a 3-month interval without intervening ischemic events or revascularisation were included in the study CART and stress echograms were independently evaluated by different observers. Stenosis was measured with calipers and a > or = 50% lumen diameter stenosis was considered significant. A reduction or lack of endocardial motion and/or wall thickening on progressive incremental stress was considered an abnormal response. TE-DASE could be successfully completed in 33/37 (90%) patients. Using a modified 16-segment model of the left ventricle (LV), 15.2 +/- 0.8 segments/patient and 501/528 (95%) segments overall could be optimally evaluated. Inter-observer concordance for an abnormal response was 94%. Predictive accuracies for one-vessel disease (1-VD), two-vessel disease (2-VD) and three-vessel disease (3-VD) were 88, 58 and 23% respectively. Overall sensitivity for detection of a significant (> or = 50%) stenosis was 72% (32% for moderate (50-69%), 90% for severe (> or = 70%) stenosis) and specificity was 96%. Diagnostic accuracy for localisation of significant stenosis was 95% for the left anterior descending artery (LAD), 86% for the left circumflex artery (LCX) and 88% for the right coronary artery (RCA). There were no major complications. We conclude that TE-DASE is a safe, reliable and easily-performed procedure and provides excellent visualisation of myocardial segments. Diagnostic accuracy for detection of severe stenosis and its localisation is excellent.

Usefulness of dipyridamole transesophageal echocardiography in the evaluation of myocardial ischemia and coronary artery flow

High-dose dipyridamole transesophageal stress echocardiography has recently been proposed as a useful and safe method to assess myocardial ischemia in patients with poor transthoracic acoustic window. It has also been shown that transesophageal echocardiography (TEE) allows the study of coronary blood flow reserve (CBFR) in the left anterior descending artery (LAD). The aim of our study was to assess whether the morphologic information and pathophysiologic data on CBFR and myocardial ischemia can be collected by a single stress TEE without comprimizing its feasibility, safety and accuracy. We studied, 29 patient with known or suspected CAD (previous myocardial infarction or angina) (Group A), and as a control group, we studied 11 patients with mitral disease or mitral prostheses (Group B). All patients underwent the coronary angiography. None of Group B patients showed significant coronary artery stenosis (> 70%). In baseline conditions left ventricular wall motion and LAD coronary blood flow velocity (CBFV) were also evaluated. The following CBFV parameters were measured: maximal diastolic velocity (MaxDV), mean diastolic velocity (MnDV), maximal systolic velocity (MaxSV), mean systolic velocity (MnSV). The ratios of dipyridamole to rest maximal and o mean to diastolic velocities (MaxDV-Dip/Max DV-rest; MnDv-Dip/MnDV-rest) were measured as indexes of CBFR. No side effects were observed and the test could be completed in all patients (feasibility 100%). Wall motion analysis was adequate in all patients (feasibility 100%). Comparison between wall motion analysis was obtained and angiographic findings shown that the overall sensitivity and specificity of TEE were 84% and 93% respectively. Sensitivity for one, two and three vessel disease was 60%, 70% and 100%, respectively. LAD CBFV was adequately recorded in 85% of patients. CBFR parameters showed a significant difference between the two groups (Max DV-Dip/Max DV-rest: 1.67 +/- 0.7 vs. 2.73 +/- 0.6, P < 0.001); comparison between Group B patients and those of Group A with angiographically documented LAD stenosis showed a statistically significant difference in CBFR parameters (MaxDV-Dip/MnDV-rest, 2.73 +/- 0.6 vs. 1.65 +/- 0.7, P < 0.001, MnDV-Dip/MnDV-rest, 2.56 +/- 0.5 vs. 1.69 +/- 0.6 < 0.001). We conclude that transesophageal stress echocardiography is a useful method to study CAD and that it is possible to assess both morphologic and pathophysiologic information during a single examination.

Transesophageal cardiac pacing during magnetic resonance imaging: feasibility and safety considerations

The feasibility and safety of transesophageal cardiac pacing during clinical MRI at 1.5 Tesla is considered. An MRI compatible pace catheter was developed. In vitro testing showed a normal performance of the pulse generator, image artifacts that extended less than 11 mm from the catheter, and a less than 5% increase in noise. Cardiac stimulation induced by MRI was not observed and, theoretically, is not expected. Potentially, tissue around the catheter tip may become heated. This heating (delta tau) was monitored. Eight dogs were exposed to MRI during pacing. For low RF radiation exposure, a time-averaged squared B1 field below 0.08 p tau 2 (SAR < 0.03 W/kg), delta tau was below 1 degree C. For high RF radiation exposure, but at normal RF radiation specific absorption rate (0.4 W/kg) delta tau was 5 degrees C. Thus, transesophageal atrial pacing during MRI at low RF exposure seems to be possible to perform cardiac stress studies or to correct unstable heart rates.

Accuracy and usefulness of atrial pacing in conjunction with transthoracic echocardiography in the detection of cardiac ischemia

Transthoracic echocardiography combined with transesophageal atrial pacing was performed in a community outpatient setting and compared with single-photon emission computed tomography (SPECT) and with coronary arteriography to determine the accuracy and usefulness of the technique. Two groups were defined: group A consisted of 65 of 189 patients who underwent all 3 procedures within a 90-day period; group B consisted of 53 patients who had atrial pacing with transthoracic echocardiography. Seventy-one patients had previously undergone atrial pacing with simultaneous transesophageal echocardiography. Atrial pacing to induce abnormal wall motion as an indicator of ischemia was performed by increasing the double product to > 20,000. We obtained a sensitivity and specificity of 87% and 88% for group A and 72% and 80% for group B, respectively. We believe that transthoracic echocardiography with atrial pacing is indicated as a means of stress echocardiography in its own right, especially in nonambulatory and chronotropically incompetent patients, as well as in the presence of an ambiguous result on SPECT testing. It is highly accurate compared with our previous study with atrial pacing and simultaneous transesophageal echocardiography, better tolerated, more easily accepted, less invasive, and less costly. Thus, it is a useful stress modality in the detection of myocardial ischemia.

Assessment of coronary artery disease by dobutamine stress echocardiography (DSE)

BACKGROUND

Dobutamine stress echocardiography (DSE) is a new non-invasive imaging modality which combines two-dimensional echocardiography with cardiovascular stress induced by dobutamine infusion. Its use in patients with suspected or documented coronary artery disease (CAD) is currently under extensive investigation.

AIMS

To illustrate the clinical utility, safety and diagnostic value of DSE.

METHODS

One hundred and thirty-seven consecutive patients referred for DSE were studied. Eighty-four patients also underwent coronary angiography.

RESULTS

Eleven patients (8%) did not undergo DSE because of poor image quality. Of the remaining 126 patients, 110 (87%) achieved their target heart rate or reached a pre-determined end point during DSE. Eight patients (6%) developed non-cardiac side effects during DSE, none of which required premature termination of the procedure. Cardiac arrhythmias were documented in 15 patients (12%) but only one required intervention. In 84 patients who underwent coronary angiography, DSE showed a sensitivity and specificity of 88% and 83%, respectively, in detecting the presence of, and 75% and 75%, respectively, in localising significant CAD. In 35 patients who underwent DSE after uncomplicated myocardial infarction, the positive and negative predictive values for cardiac events following infarction in a six-month followup period were 74% and 62%, respectively.

CONCLUSIONS

DSE is a well tolerated, safe and useful test in detecting and localising significant CAD. It can also provide useful post-infarctional prognostic information.

Relation between ischemic threshold measured during dobutamine stress echocardiography and known indices of poor prognosis in patients with coronary artery disease

BACKGROUND

Stress echocardiography has become an accepted methodology for the evaluation of coronary artery disease. One potential advantage of dobutamine over other stressors used with echocardiography is the possibility of assessing the ischemic threshold. However, whether this measurement correlates with indices associated with adverse outcome has not been established.

METHODS AND RESULTS

One hundred four patients (91 men and 13 women; age, 61 +/- 9 years) with coronary artery disease were studied with transesophageal echocardiography during infusion of dobutamine 2.5 to 40 microgram/kg per minute. When regional dyssnergy developed, the dobutamine ischemic threshold (the dose of dobutamine at which induced regional wall motion abnormalities were first detected) was identified. The dobutamine stress echocardiogram was abnormal in 90 patients (sensitivity, 87%). The dobutamine ischemic threshold was 25.4 +/- 11.2 micrograms/kg per minute in patients with single-vessel disease, 14.4 +/- 7.9 in patients with two-vessel disease, and 9.1 +/- 7.9 in patients with three-vessel disease (P < .0001). The dobutamine ischemic threshold correlated with the ejection fraction response to exercise measured by radionuclide angiography: Patients with low ischemic threshold had a mean fall in ejection fraction, and patients with high ischemic threshold or normal tests had a mean increase in ejection fraction.

CONCLUSIONS

In patients with coronary artery disease, the ischemic threshold measured during dobutamine stress echocardiography correlates with both the number of stenosed vessels and the left ventricular ejection fraction response to exercise. Because these variables are associated with poor prognosis, these findings provide further support regarding the utility of dobutamine stress echocardiography in the clinical evaluation of patients with chronic coronary artery disease.

Transesophageal echocardiography in myocardial ischemia: a review

This article reviews established as well as emerging fields in the application of transesophageal echocardiography (TEE) in the investigation of myocardial ischemia. TEE already has a well defined and established role in stress echocardiography in patients with poor transthoracic acoustic window, and in the detection of intraoperative myocardial ischemia in cardiac and noncardiac surgery. The evaluation of right ventricular ischemia and infarction and the assessment of coronary flow reserve (CFR) are relatively new fields in the application of TEE and the potential of this technique has not yet been fully evaluated. The evidence collected and reviewed in this article is still preliminary but it presupposes a significant role of TEE in the diagnosis and pathophysiological assessment of myocardial ischemia.

Application and perspectives of transesophageal stress echocardiography using monoplane and biplane instruments

Transesophageal stress echocardiography has been reported to have a high sensitivity and specificity for noninvasive identification and assessment of coronary artery disease. Its advantage is the virtually never obstructed acoustic window on the heart yielding superior image quality in almost all patients. Pharmacological stress as well as simultaneous atrial pacing--attaching electrodes to the echoscope--have been applied as stress modalities. Both transesophageal stress echocardiography modalities have been shown to be well tolerated, safe, and feasible in most patients. These promising initial experiences led to clinical application of this method for preoperative risk evaluation, for detection of restenosis after PTCA, and for evaluation of hibernating myocardium. This technique was also successful for evaluation of stress induced changes of transmitral and pulmonary venous flow in patients with left ventricular hypertrophy and coronary artery disease. Although all studies published so far were performed with monoplane technique, the sensitivity for detection of one-vessel and, even more so, multivessel disease was high. However, apical and basal wall-motion abnormalities may go undetected using monoplane equipment. The advent of biplane transesophageal imaging enables the visualization of more ventricular segments. Future studies will show to which degree biplane transesophageal stress echocardiography improves the diagnostic accuracy.

Accuracy and usefulness of atrial pacing in conjunction with transesophageal echocardiography in the detection of cardiac ischemia (a comparative study with scintigraphic tomography and coronary arteriography)

A comparative study of transesophageal echocardiography with single-photon emission computed tomography (SPECT) and coronary arteriography was performed in a community outpatient setting to determine accuracy and feasibility of the technique. Forty-one of 55 patients underwent all 3 procedures within a 90-day period. Fourteen patients underwent only SPECT and were compared with transesophageal echocardiography with pacing (TEEP). Atrial esophageal pacing was performed with transesophageal echocardiography to increase double product and induce ischemia, which would manifest as abnormal wall motion. The results in these patients indicated a sensitivity and specificity of 92% and 87% for TEEP and 96% and 82% for SPECT, respectively, using angiography as the gold standard. In 14 patients, the sensitivity of TEEP using SPECT as standard was 80% and the specificity was 87%. The 1 view that appeared to pick up the highest yield of abnormalities was the transgastric short-axis view. Thus, TEEP is indicated in the detection of chronotropically incompetent patients and those unable to exercise whose transthoracic images are not optimal. It is highly accurate compared with angiography or SPECT.

Transesophageal dobutamine stress echocardiography in the evaluation of coronary artery disease

OBJECTIVES

The goal of this study was to determine the feasibility, safety, sensitivity and specificity of transesophageal dobutamine stress echocardiography for the detection of coronary artery disease.

BACKGROUND

Dobutamine stress echocardiography has been shown to be an extremely sensitive and specific noninvasive technique for the detection of myocardial ischemia. However, inadequate transthoracic images preclude the use of dobutamine stress echocardiography in a small but significant group of patients. Transesophageal echocardiography provides better resolution than that obtained with routine transthoracic imaging.

METHODS

Patients scheduled for routine cardiac catheterization underwent transesophageal dobutamine stress echocardiography. All patients underwent coronary arteriography within 48 h of the study, and lesion severity was determined by quantitative coronary angiography. Significant coronary obstruction was defined as stenosis > 50%.

RESULTS

Fifty-one male patients were enrolled in the study; six were excluded for technical reasons. There were no adverse outcomes or complications. Of 27 patients with significant coronary artery disease, 22 had positive study results (sensitivity 82%). Of 13 patients without significant obstructive coronary disease, 1 had a false positive study result (specificity 93%). In patients with a minimal lumen diameter < 1.25 mm, sensitivity was > 80%, and in patients with a minimal lumen diameter > 1.5 mm, sensitivity was < 70%, suggesting that lesions with a minimal lumen diameter < 1.25 mm are more likely to be physiologically significant.

CONCLUSIONS

Transesophageal dobutamine stress echocardiography is a feasible, safe and accurate technique for the detection of myocardial ischemia. There are inherent limitations to this technique in that transesophageal echocardiography must be performed. Transesophageal dobutamine stress echocardiography may allow extension of dobutamine stress testing to patients with inadequate transthoracic echocardiographic imaging and may provide an opportunity for further research applications.

Effects of nicorandil on regional perfusion and left ventricular function

Left ventricular function and regional perfusion were evaluated by two study designs in patient groups with stable ischemic coronary artery disease (CAD): (1) using conventional left ventricular angiographies and (2) applying myocardial contrast echocardiography. The aim of the studies was to establish the effects of sublingually or orally applied nicorandil (N) on pacing-induced myocardial ischemia (MIS). In the first angiographic study, in nine patients with ischemic CAD and with pacing-inducible MIS, the effect of N, 20 mg sublingually, on hemodynamics and regional wall motion (RWM) were studied. There were no parameter changes without MIS being induced when comparing measurements at the 7th and 14th minute after N application to control values (p > 0.05). In the 15th and 16th minutes after N, pacing-induced MIS could no longer be elicited but left ventricular pump function improved; comparing MIS with N versus MIS without N: ejection fraction improved by 21%, cardiac index by 37%, and RWM by 21%, while filling pressure fell by 41% and systemic vascular resistance fell by 29%. Thus, N-mediated "protection from ischemia" with rather improved hemodynamics and RWM corresponds with alterations that theoretically could have been expected after nitroglycerin given under the above conditions. In the second echocardiographic study, regional perfusion was assessed in 10 patients by intracoronary injection of a newly developed echo contrast medium (ECM) and measurement of ECM washout halftime (t1/2) over opacified myocardial regions of interest, which displayed wall motion abnormalities already at rest.(ABSTRACT TRUNCATED AT 250 WORDS)

What is the most appropriate variable for estimation of mean pulmonary capillary wedge pressure by transesophageal pulsed Doppler echocardiography?

Although left ventricular (LV) inflow and pulmonary venous (PV) flow variables estimated by transesophageal Doppler echocardiography (TEE) reflect pulmonary capillary wedge pressure (PCWP), they are also affected by changes in cardiac function. The purpose of the present study was to detect the most appropriate variable for the estimation of PCWP by TEE in patients (pts) with ischemic heart disease. Several variables of LV inflow and left upper PV flow were compared with PCWP in 36 pts (six with angina pectoris and 30 with old myocardial infarction). Early diastolic flow (E) and atrial contraction flow (A) were used as LV inflow, while systolic forward flow (X), diastolic forward flow (Y) and atrial contractile reversal flow (z) were used as PV flow. The peak velocity of each flow wave (Ep, Ap, Xp, Yp, and Zp) and the time-velocity integral (Ei, Ai, Xi, Yi, and Zi) were measured. The ratio of Ep to Ap (Ep/Ap), Ei to Ai (Ei/Ai), Xp to Yp (Xp/Yp), Xi to Yi (Xi/Yi), Zp to Ap (Zp/Ap), Zi to Ai (Zi/Ai) and the systolic fraction of PV forward flow were calculated. Among these variables, the Zi/Ai ratio was most strongly correlated with PCWP (R = 0.80). The Zi/Ai ratio may not be influenced by atrial function because the augmentation of atrial pump function increases Zi as well as Ai, and this may be one reason why the ratio correlated well with PCWP.

CONCLUSION

The Zi/Ai ratio is a new useful variable for estimating PCWP by TEE.

Relation between thallium uptake and contractile response to dobutamine. Implications regarding myocardial viability in patients with chronic coronary artery disease and left ventricular dysfunction

BACKGROUND

Both thallium scintigraphy and dobutamine echocardiography have been used to assess myocardial viability. However, thallium uptake and the inotropic response to dobutamine are expressions of different cellular phenomena. The present study was undertaken to investigate the relation between the two methods in patients with chronic coronary artery disease and left ventricular dysfunction to derive insights into the mechanisms related to myocyte viability.

METHODS AND RESULTS

Thirty patients (28 men and 2 women; age, 59 +/- 10 years) with chronic coronary artery disease and impaired left ventricular systolic function at rest (mean ejection fraction, 32 +/- 9%) were included in the study. Patients underwent transesophageal echocardiography during incremental doses of dobutamine from 2.5 to a maximum of 40 micrograms.kg-1.min-1 and single photon emission computed tomographic thallium scintigraphy using a stress-redistribution-reinjection protocol. The left ventricle was divided into 16 segments for analysis of echocardiographic and thallium images. Segmental myocardial contractile function was graded as normal, hypokinesis, akinesis, or dyskinesis at each incremental dose of dobutamine. Thallium uptake in each myocardial segment was graded on a 5-point scale from 0 (absent) to 2 (normal) for each of the stress, redistribution, and reinjection images. A segment was considered viable if the assigned thallium score was 1 or higher (normal uptake or only mild to moderate defect) in any of the stress, redistribution, or reinjection images. Among 472 myocardial segments available for analysis, 311 had resting wall motion abnormalities, of which 56% (173/311) showed contractile improvement with dobutamine (usually first observed at < or = 10 micrograms.kg-1.min-1) and 84% (262/311) were considered viable by thallium scintigraphy (P < .0001). Of the 262 segments considered viable by thallium, 167 (64%) had a contractile improvement with dobutamine; in contrast, only 6 of the 49 segments (12%) considered nonviable by thallium had a positive dobutamine response (P < .0001). Furthermore, a positive inotropic response to dobutamine was significantly related to the magnitude of thallium uptake: the proportion of segments with a positive dobutamine response rose with increasing magnitude of thallium uptake (P < .001). The disagreement between the two tests was related primarily to segments considered viable by thallium that did not show contractile improvement with dobutamine.

CONCLUSIONS

These findings demonstrate the existence of a relation between thallium uptake and the inotropic response to dobutamine in patients with chronic coronary artery disease and left ventricular dysfunction. However, the proportion of segments showing a positive response to dobutamine is significantly lower than those with thallium uptake, suggesting that the cellular mechanisms responsible for a positive inotropic response to adrenergic stimulation require a higher degree of myocyte functional integrity than those responsible for thallium uptake.

Coronary flow reserve assessment by dobutamine transesophageal Doppler echocardiography

OBJECTIVES

This study attempted to determine the sensitivity and specificity of coronary flow reserve derived using transesophageal echocardiography for left anterior descending coronary artery stenosis.

BACKGROUND

Transesophageal echocardiography can be used to measure coronary flow velocity and may provide a less invasive means of assessing coronary flow reserve.

METHODS

Seventy-eight adult patients were studied by pulsed Doppler transesophageal echocardiography of the proximal left anterior descending coronary artery during a control period and peak (i.e., 40 micrograms/kg body weight per min) dobutamine infusion. Coronary flow reserve index was calculated as the ratio of maximal diastolic coronary velocity at peak dobutamine infusion to the control level and was considered abnormal if < 1.81. Two-dimensional transesophageal left ventricular views were obtained for analysis of wall motion.

RESULTS

Coronary angiography showed > or = 70% (group A, n = 18), 0% to < 70% (group B, n = 21) and no (group C, n = 39) left anterior descending coronary artery diameter stenosis. An abnormal coronary flow reserve index did not differ from a new regional wall motion abnormality in sensitivity for left anterior descending coronary stenosis in group A (15 [83%] of 18 vs. 15 [83%] of 18, p = NS) but was significantly more sensitive in group B (12 [57%] of 21 vs. 2 [10%] of 21, p < 0.025). The specificity for no left anterior descending coronary stenosis in group C between a normal coronary flow reserve index and no new regional wall motion abnormality did not differ (87% vs. 97%, p = NS).

CONCLUSION

Doppler coronary flow reserve and two-dimensional dobutamine transesophageal echocardiography are equally sensitive for the detection of left anterior descending coronary stenosis > or = 70% and equally specific. However, Doppler coronary flow reserve, compared with two-dimensional dobutamine transesophageal echocardiography, is more sensitive for intermediate left anterior descending coronary stenosis and may play a significant adjunctive role to cardiac catheterization and other noninvasive techniques for assessing coronary artery disease.

Diagnostic and prognostic value of stress testing in older persons

OBJECTIVE

To review the diagnostic and prognostic utility of exercise and pharmacologic stress testing in older individuals.

DATA SOURCE

A computer-assisted search of the literature, followed by a manual reference review of pertinent articles.

STUDY SELECTION

Studies addressing the use of exercise and pharmacologic stress testing for coronary artery disease (CAD) detection and prognosis were reviewed. Emphasis was placed on those studies applying these procedures to older populations.

DATA EXTRACTION

Pertinent data were extracted regarding the diagnostic and prognostic accuracy and safety of exercise and nonexercise stress testing techniques in older patients.

DATA SYNTHESIS

Available data from relevant articles were summarized and the merits and limitations of the available techniques discussed.

CONCLUSIONS

Numerous studies over the past 2 decades support the usefulness of the exercise ECG and exercise thallium-201 perfusion scan for detecting CAD in older populations. Although exercise echocardiography generally appears to have diagnostic and prognostic accuracy similar to thallium-201 imaging, greater technical difficulty with this technique is frequently encountered in older patients. Non-exercise forms of stress testing, particularly those employing pharmacologic agents such as dipyridamole, adenosine, or dobutamine, combined with either thallium-201 scintigraphy or echocardiography, allow accurate CAD diagnostic and prognostic assessment in even very frail older patients. Additional studies are needed to compare the accuracy and cost-benefit ratio of the many stress testing modalities now available for older patients.

Left and right heart Doppler stress echo in congestive heart failure

Doppler echocardiographic assessment of the left and right ventricular function at rest, during and 6 minutes after submaximal exercise was performed in 60 patients with a mean age of 43 +/- 11 years suffering from heart failure classified stage I-III according to the NYHA-criteria and 10 volunteers with a mean age of 36 +/- 9 years who served as a control group. At mitral (m) and tricuspid (t) valve early diastolic peak-flow velocity (VEm, VEt), atrial peak-flow velocity (VAm, VAt), speed-time integrals (Em, Et, Am, At) and the ratios (VE/VAm, VE/VAt, E/Am, E/At) were determined. The left ventricular end-diastolic diameter (LVEDD) and the right ventricular outflow tract (RVOT) were measured in addition. The left ventricular ejection fraction (LVEF) was decreased to < 36% in 9 patients (group 1). In 51 individuals LVEF was found to be > 35% but < 50% or LVEF was shown to be > 50% but VE/VAm-ratio was found to be < 1 (group 2). Out of all the determined parameters, VE/VAt, VEt and VAm during exercise were found to be the most sensitive parameters for the detection of early to advanced grade left heart failure.

Transesophageal dobutamine stress echocardiography for evaluation of patients with coronary artery disease

OBJECTIVES

The present study was undertaken to determine the safety, feasibility and diagnostic accuracy of transesophageal dobutamine stress echocardiography for the evaluation of patients with known or suspected coronary artery disease.

BACKGROUND

Dobutamine stress echocardiography has proved to be a valuable method for detecting and prognosticating ischemic heart disease. In addition, it may provide accurate information about myocardial viability in patients with systolic dysfunction. However, in some patients the technique may be limited by poor myocardial imaging with the conventional transthoracic approach.

METHODS

Seventy-six patients (62 men, 14 women; mean age +/- SD 60 +/- 10 years) who underwent coronary angiography were included in the study. Transesophageal stress echocardiograms were performed after withdrawal of antianginal medications for > or = 48 h. Dobutamine was infused at a starting dose of 2.5 micrograms/kg body weight per min and was increased by 5-micrograms/kg per min increments every 5 min to a maximum of 40 micrograms/kg per min. Two-dimensional views were acquired at each stage and digitized for subsequent analysis. The left ventricle was divided into 16 segments, and each segment was assigned to a major coronary artery with the use of a model of regional distribution of coronary perfusion.

RESULTS

Sixty-two of the 76 patients had angiographic evidence of coronary artery disease. New or worsening regional wall motion abnormalities developed during dobutamine infusion in 55 of these 62 patients and in none of the 14 patients with normal coronary arteries (sensitivity 89%, specificity 100%, overall accuracy 91%). Regional wall motion abnormalities in the distribution of more than one major coronary artery were seen in 3 of the 25 patients with single-vessel coronary artery disease and in 30 of the 37 patients with multivessel disease (p < 0.0001). The test was successfully completed in 73 (96%) of the 76 patients; it was discontinued in the remaining 3 patients because of intolerance to the probe. No major complications occurred in any patient. Minor complications developed in seven patients but did not affect the diagnostic accuracy of the test.

CONCLUSIONS

Transesophageal dobutamine stress echocardiography is a safe, feasible and accurate method for assessing coronary artery disease. Its use should be considered in patients who have a suboptimal ultrasound window, and it provides an excellent tool for clinical investigations based on ultrasound imaging of the myocardium.

Assessment of viable myocardium by dobutamine transesophageal echocardiography and comparison with fluorine-18 fluorodeoxyglucose positron emission tomography

OBJECTIVES

The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction.

BACKGROUND

Experimental and clinical studies have shown that dobutamine can recruit a contraction reserve in postischemic viable but akinetic segments, indicating that dobutamine-induced functional recovery is a potential ultrasound marker of myocardial viability.

METHODS

Forty patients underwent rest and dobutamine transesophageal echocardiography (dobutamine 5, 10 and 20 micrograms/kg body weight per min) and fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography at rest. Three representative short-axis tomograms and a transverse four-chamber-view were used for wall motion and F-18 fluorodeoxyglucose-uptake analysis in corresponding myocardial regions. A basally asynergic segment was considered viable by transesophageal echocardiography if dobutamine-induced systolic wall motion could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion by left ventriculography.

RESULTS

Functional recovery within the infarct region was found in 21 (53%) of 40 patients during dobutamine infusion. Infarct region-related viability by F-18 fluorodeoxyglucose uptake was diagnosed in 25 (63%) of 40 patients, yielding a diagnostic agreement between both techniques in 90% of patients. In 210 (89%) of 235 akinetic segments at rest, data on myocardial viability were concordant by the two techniques. The positive and negative predictive accuracy of dobutamine transesophageal echocardiography for viability defined by F-18 fluorodeoxyglucose uptake was 81% and 97%, respectively. Such uptake was significantly different (p < 0.001) between segments remaining akinetic (mean +/- SD 45 +/- 9%) during dobutamine infusion and segments with a dobutamine-induced contraction reserve (68 +/- 11%).

CONCLUSIONS

Dobutamine transesophageal echocardiography provides a promising low cost and widely available approach to unmask myocardial viability in patients with chronic myocardial infarction, and results compare favorably with those of F-18 fluorodeoxyglucose positron emission tomography.

Dobutamine two-dimensional transesophageal echocardiographic stress testing for detection of coronary artery disease

Atrial pacing and dipyridamole transesophageal echocardiography have been shown to be sensitive and specific tests for the detection of coronary artery disease. However, the sensitivity and specificity of dobutamine transesophageal echocardiography have not been reported. The purpose of this study was to determine the feasibility, sensitivity, and specificity of dobutamine transesophageal echocardiography for the detection of coronary artery disease. Transesophageal echocardiographic assessment of left ventricular function was performed in 81 adult patients aged 62 +/- 12 years during stepwise infusion of dobutamine from 5.0 to 40 micrograms/kg/min. Ischemia was diagnosed by the development of severe hypokinesis, akinesis, or dyskinesis of a previously contractile left ventricular segment. Coronary artery disease was defined by angiography as a reduction in luminal diameter of > or = 70% of an epicardial or > or = 50% of the left main coronary artery. In patients who had undergone coronary artery bypass graft surgery, a stenotic bypass graft was defined as a reduction in luminal diameter of > or = 70%. In patients without previous CABG, significant coronary artery disease was present in 21 patients: 5 with single-vessel disease, 7 double-vessel disease, 8 triple-vessel disease, and 1 left main coronary disease. Dobutamine transesophageal echocardiography had a sensitivity of 90% (19 of 21) and specificity of 94% (49 of 52) for the detection of coronary artery disease. In patients with previous CABG (n = 8), the sensitivity and specificity for the detection of bypass graft stenosis were 100% (4 of 4) and 75% (3 of 4), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased thickening of normal myocardium with transient increased wall thickness during stress echocardiography with atrial pacing

Stress echocardiography is used increasingly in the evaluation of coronary artery disease. The echocardiographic evaluation of ischemia is based on stress-induced changes in wall motion and wall thickening of the ischemic segments. Studies have demonstrated that left ventricular volumetric changes may induce changes in wall thickness. The aim of the study was to evaluate whether significant changes in ventricular volume, wall thickness, and wall thickening occur during stress echocardiography with atrial pacing. Seven German Landrace female pigs were studied 4 weeks after the induction of a small myocardial infarction. Echocardiographic measurements were conducted in noninfarcted segments on the short-axis view at baseline and during atrial pacing at 120, 150, and 180 beats/min. End-diastolic circumferential area decreased from 12.3 +/- 2.0 cm2 at baseline to 8.9 +/- 1.9 cm2 at 180 beats/min of atrial pacing (p < 0.01). Mean wall thickness (interventricular septal plus posterior wall thickness divided by 2) increased markedly and progressively from 6.7 +/- 0.6 mm at baseline to 9.8 +/- 1.0 mm at 180 beats/min (p < 0.01). The increase in wall thickness correlated inversely with end-diastolic area (r = -0.57; p < 0.01). Percent systolic thickening decreased from 38.9 +/- 12.0 at baseline to 14.9 +/- 7.4 at 180 beats/min of atrial pacing (p < 0.01). The decrease in percent wall thickening correlated with the increase in wall thickness (r = -0.71; p < 0.01). In conclusion, this study shows that a marked increase in wall thickness (pseudohypertrophy) and decrease in percent systolic thickening are observed during rapid atrial pacing in normal myocardium and do not indicate stress-induced left ventricular dysfunction.

Influence of pacing-induced myocardial ischemia on left atrial regurgitant jet: a transesophageal echocardiographic study

OBJECTIVES

We investigated the influence of pacing-induced myocardial ischemia on systolic regurgitant jet in the left atrium, using simultaneous transesophageal echocardiography and transesophageal atrial pacing.

BACKGROUND

In vitro studies have shown that ischemia-induced mitral regurgitation may occur as a result of mitral leaflet malcoaptation or (global) left ventricular dysfunction. However, no transesophageal echocardiographic study has thus far been performed to demonstrate the mechanism and extent of mitral regurgitation during myocardial ischemia in patients.

METHODS

In 24 patients (mean [+/- SD] age 57 +/- 10 years) with (15 patients) and without (9 control subjects) coronary artery disease, heart rate, blood pressure and systolic regurgitant jet were assessed before and immediately after pacing. Pacing was increased stepwise up to 160 beats/min to provoke wall motion abnormalities while the left ventricular short axis was monitored at the midpapillary muscle level. Other variables obtained before and at peak pacing included left ventricular end-diastolic and end-systolic areas and left ventricular end-diastolic and end-systolic endocardial segmental lengths.

RESULTS

Heart rate and blood pressure before and after pacing were not significantly different in control subjects or in patients. At baseline, a jet was present in all but three control subjects. New or increased anterior or posterior wall motion abnormalities were observed during pacing in seven and eight patients, respectively. End-systolic left ventricular areas and segment lengths were significantly reduced in control subjects compared with patients with coronary artery disease at peak pacing (p < 0.05). The increase in systolic regurgitant jet was significantly greater in patients (2.0 +/- 1.1 to 3.1 +/- 1.8 cm2 vs. 0.7 +/- 0.7 to 0.9 +/- 0.9 cm2 [after pacing], p < 0.01). This effect was greater in patients with posterior than with anterior wall motion abnormalities (3.5 +/- 1.6 vs. 2.1 +/- 1.2 cm2 [after pacing], p < 0.05).

CONCLUSIONS

Quantitative changes in geometry and function of the left ventricle caused by pacing-induced myocardial ischemia augments systolic regurgitant jet size. An increase in the jet during atrial pacing is associated with new or increased wall motion abnormalities, especially of the posterior wall. Pacing-induced anterior wall motion abnormalities appear not to be related directly to an increase in the jet.

Usefulness of transesophageal atrial pacing combined with two-dimensional echocardiography (echo-pacing) in predicting the presence and site of residual jeopardized myocardium after uncomplicated acute myocardial infarction

The usefulness of transesophageal atrial pacing combined with 2-dimensional echocardiography (echo-pacing) in predicting the presence and site of jeopardized myocardium, defined as areas of myocardium perfused by a vessel with a stenosis > or = 75% or by a collateral circulation if the supplying vessel was occluded, was evaluated in 31 patients with uncomplicated acute myocardial infarction who underwent coronary angiography. All 5 patients without jeopardized myocardium had a negative test, whereas 24 of 26 with jeopardized muscle had a positive test (sensitivity 92%; specificity 100%). To identify the site of jeopardized myocardium, tests that were positive for development of new asynergies were analyzed further, distinguishing those positive in the infarct or remote zone. Seven of 8 patients with new asynergies in the remote zone had areas of jeopardized myocardium outside the territory of distribution of the infarct-related vessel, whereas only 2 of 12 with new asynergies in the infarct zone had areas of jeopardized myocardium outside that territory (p < 0.01), correctly predicting the site of jeopardized myocardium in 17 of 20 cases. In conclusion, echo-pacing is useful for detecting the presence and site of jeopardized myocardium after an acute myocardial infarction.

Simultaneous transesophageal echocardiography and atrial pacing: assessment of the functional significance of coronary artery disease before surgical treatment of an abdominal aneurysm

Conventional active stress tests for the evaluation of coronary artery disease are not feasible for patients in whom a significant blood pressure increase during a stress procedure should be avoided, for example, those with a coexisting aortic aneurysm. Transesophageal echocardiography (TEE) with simultaneous atrial pacing is a new, highly specific, and sensitive stress technique for the detection of coronary artery disease. Furthermore, TEE can be performed safely with only mild blood pressure increases. Therefore in the present case report of a 70-year-old male, application of combined TEE and atrial pacing was used successfully to exclude the hemodynamic significance of a circumflex artery stenosis and avoided a significant blood pressure increase before surgical correction of an abdominal aortic aneurysm.

Biplane transesophageal pacing echocardiography compared with dipyridamole thallium-201 single-photon emission computed tomography in detecting coronary artery disease

TPE is a new diagnostic technique that uses simultaneous graded transesophageal left atrial pacing and biplane transesophageal echocardiography for the detection of pacing-induced wall motion abnormalities. In a prospective study 30 patients underwent biplane TPE, dipyridamole thallium-201 single-photon emission computed tomography (SPECT), and coronary arteriography. The sensitivity (86% vs 95%, p = not significant [NS]), specificity (89% vs 56%, p = NS), positive predictive value (95% vs 73%, p = NS), and negative predictive value (83% vs 83%, p = NS) of biplane TPE and thallium-201 SPECT in identifying patients with significant coronary artery disease was similar. In the 90 vascular territories analyzed, the agreement between biplane TPE and thallium-201 SPECT for presence or absence of significant disease was 71%. Analysis of the three major vascular territories demonstrated that each imaging modality had a high sensitivity and specificity in the left anterior descending and right coronary artery segments. However, the two techniques demonstrated poorly sensitivity in the segmental distribution of the circumflex coronary artery. In conclusion, biplane TPE compared favorably with thallium-201 SPECT in terms of safety and accuracy for detecting significant coronary artery disease. Accordingly, biplane TPE may be a suitable alternative for those patients with nondiagnostic thallium-201 SPECT studies and in those with contraindications to adenosine or dipyridamole.