Quantitative two dimensional echocardiography during bicycle exercise in normal subjects

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

Dobutamine-stress magnetic resonance microimaging in mice : acute changes of cardiac geometry and function in normal and failing murine hearts

The aim of this study was to assess the capability of MRI to characterize systolic and diastolic function in normal and chronically failing mouse hearts in vivo at rest and during inotropic stimulation. Applying an ECG-gated FLASH-cine sequence, MRI at 7 T was performed at rest and after administration of 1.5 microgram/g IP dobutamine. There was a significant increase of heart rate, cardiac output, and ejection fraction and significant decrease of end-diastolic and end-systolic left ventricular (LV) volumes (P<0.01 each) in normal mice during inotropic stimulation. In mice with heart failure due to chronic myocardial infarction (MI), MRI at rest revealed gross LV dilatation. There was a significant decrease of LV ejection fraction in infarcted mice (29%) versus sham mice (58%). Mice with MI showed a significantly reduced maximum LV ejection rate (P<0.001) and LV filling rate (P<0.01) and no increase of LV dynamics during dobutamine action, indicating loss of contractile and relaxation reserve. In 4-month-old transgenic mice with cardiospecific overexpression of the beta(1)-adrenergic receptor, which at this early stage do not show abnormalities of resting cardiac function, LV filling rate failed to increase after dobutamine stress (transgenic, 0.19+/-0.03 microL/ms; wild type, 0.36+/-0.01 microL/ms; P<0.01). Thus, MRI unmasked diastolic dysfunction during dobutamine stress. Dobutamine-stress MRI allows noninvasive assessment of systolic and diastolic components of heart failure. This study shows that MRI can demonstrate loss of inotropic and lusitropic response in mice with MI and can unmask diastolic dysfunction as an early sign of cardiac dysfunction in a transgenic mouse model of heart failure.

Biventricular response to supine physical exercise in young adults assessed with ultrafast magnetic resonance imaging

Simultaneous assessment of left ventricular (LV) and right ventricular (RV) response to exercise is limited with the current imaging modalities. Magnetic resonance imaging (MRI) techniques are now under development that allow near real-time evaluation of biventricular function under physical stress. This approach may open new avenues to study heart function in response to exercise in health and disease. The aim of this study was to evaluate biventricular response to supine physical exercise using ultrafast MRI. Biventricular volumes and function were examined in 16 healthy volunteers (mean age 18 +/- 2 years) using an ultrafast MRI sequence at rest and during an exercise protocol on a MRI compatible bicycle ergometer. Exercise level was individualized at the workload corresponding to 60% of the maximal oxygen uptake. All subjects completed the exercise MRI examination, allowing functional evaluation. Stroke volume of both ventricles increased from rest to exercise (left ventricle, 89 +/- 14 ml vs 102 +/- 19 ml, p < 0.05; right ventricle, 88 +/- 14 ml vs 101 +/- 16 ml, p < 0.05). Ejection fraction also increased in both ventricles from rest to exercise (left ventricle, 63 +/- 6% vs 74 +/- 6%, p < 0.05; right ventricle, 61 +/- 6% vs 70 +/- 6%, p < 0.05). End-systolic volume of the left and right ventricles decreased from rest to exercise (left ventricle, -33 +/- 12%, p < 0.05; right ventricle, -25 +/- 12%, p < 0.05), whereas LV and RV end-diastolic volumes remained unchanged. The results fit well with current concepts of cardiac physiology, and therefore we conclude that ergometer-induced exercise MRI is a valid approach to assess physiologic changes in LV and RV function simultaneously.

Change in left atrial and ventricular dimensions during and immediately after exercise

PURPOSE

The aim of this study was to evaluate differences in the left atrial (LAD), total ventricular end-diastolic (TEDD), end-systolic diameters (TESD), and left ventricular shortening fraction (SF) compared with heart rate (HR) and systolic blood pressure (SBP) during exercise and recovery.

METHODS

Healthy young male (N = 15) and female (N = 16) subjects performed an incremental cycle ergometer test in upright position, and three phases of energy supply were defined by means of blood lactate concentration (LA) and respiratory gas exchange variables (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic). Subjects were required to rest their arms on a steering bar and to lean their upper body forward; two dimensional (2-D) echocardiograms were obtained over the left parasternal area at rest (R), at the end of each phase, immediately within 15 s post, and 6 min after exercise (6 min). By using VINGMED's "Anatomical M-Mode," it was possible to extract M-Mode Sweeps from stored 2-D-Loops and perform the M-Mode measurement.

RESULTS

In contrast to the significant decrease in TEDD and TESD from III to 15 s up to resting values and the significant increase in SF from III to 15 s, the moderate decrease in HR immediately post exercise (15 s) was not significant. The SBP showed a significantly decrease from III to 15 s; in contrast to TEDD, TESD, and SF, the values at 15 s were comparable with the values at II. For LAD, significant increase during exercise and a decrease during recovery were observed. Sex-specific differences of changes in measured variables could not be found.

CONCLUSION

We concluded that post exercise measurement of left ventricular and atrial dimensions or SF were not valid to describe heart function at maximal exercise although immediately post exercise HR was near maximal level.

Left ventricular function during exercise in athletes and in sedentary men

Aim of this study was to evaluate left ventricular function during exercise in 10 male elite runners and in 10 sedentary males. End-diastolic (EDV) and end-systolic volume (ESV), left ventricular ejection fraction (EF), early peak transmitral flow velocity (peak E), time-velocity integral of mitral inflow (m-TVI); mitral cross sectional area (m-CSA); mitral stroke volume (SV), and cardiac output (CO) were measured by echo-Doppler. We simultaneously analyzed: VO2max by spirometric method, mean arterial blood pressure (MAP) by sphygmomanometer, and heart rate (HR) by ECG. The parameters were measured under basal conditions (level 1), at 50% of maximal aerobic capacity (level 2), at peak of exercise (level 3) and during recovery. Ejection fraction in athletes increased significantly at peak of exercise through Frank-Starling mechanism. Stroke volume and cardiac output increased significantly in athletes at peak of exercise. Left ventricular diastolic function was superior in athletes versus controls: in fact, higher peak E in athletes enhanced early diastolic ventricular filling. Therefore, the athletes showed complex cardiovascular adjustments induced by training, which allowed an higher peak working power, a greater cardiac output, and VO2max when compared with an untrained control population.

Cardiovascular function and glucocorticoid replacement in patients with hypopituitarism

OBJECTIVE

Retrospective analysis suggests an increased mortality from cardiovascular disease in hypopituitary adults; GH deficiency has been postulated to account for this. However, glucocorticoid replacement doses of 30 mg/day of hydrocortisone (HC) may be excessive, and could therefore be implicated in the increased cardiovascular mortality in this group of patients. The aims of this study were to establish whether patients with hypopituitarism have any abnormalities of the cardiovascular system compared to a control group and whether any of these parameters might be improved by reducing the replacement dose of glucocorticoid.

PATIENTS AND MEASUREMENTS

A prospective analysis of cardiovascular function was carried out in 13 patients with hypopituitarism on routine replacement therapy and 20 normal controls who were matched for age and body mass index (BMI). Twenty-four-hour ambulatory blood pressure (BP), erect and supine BP, echocardiography, forearm plethysmography and cardiovascular reflexes in response to tilt, Valsalva and isometric hand grip were performed on controls and on patients taking 30 mg/day of HC and repeated following a reduction in HC dose to 15 mg/day for 3 months. Weight, plasma and urinary electrolytes, 24-hour urinary cortisol excretion, glucose, HbA1C and pituitary function were also assessed on HC 30 mg/day and 15 mg/day.

RESULTS

Mean 24-hour ambulatory BP, in addition to day and night time BP, was lower in patients than in controls (achieving statistical significance in the male subgroup) and did not change significantly with a reduction in HC dose. Erect and supine BP was also lower in patients compared to controls and there was no evidence of postural hypotension following a reduction in HC dose to 15 mg/day. Systolic and diastolic left ventricular dimensions, interventricular septal thickness, ejection fraction and fractional shortening were similar in controls and patients and did not alter with a reduction in HC dose. Systolic and diastolic BP and heart rate responded appropriately to all tests of cardiovascular reflexes (tilt, Valsalva and isometric handgrip) in hypopituitary patients though again measurements of systolic BP were significantly lower in patients during these tests, independent of HC dose. Forearm plethysmography was similar in patients receiving 30 mg of HC and controls but forearm blood flow increased significantly when the HC dose was reduced to 15 mg/day. There was no change in weight, plasma and urinary electrolytes, glucose and HbA1C or pituitary function in the patient group throughout the study.

CONCLUSIONS

In contrast to other studies we have failed to confirm cardiovascular dysfunction in GH deficient hypopituitary adults. Indeed, cardiovascular protection may be conferred on this group by the lower BP levels. Although a reduction in hydrocortisone dose was well tolerated in all patients, it appeared to confer no additional clinical benefit over the 3-month study period. In view of the conflicting data on cardiovascular function in hypopituitary patients, further prospective mortality studies are required in patients with adult GH deficiency.

Pharmacologically induced myocardial ischemia: a comparison of dobutamine and dipyridamole

The purpose of our study was to compare the ability of dobutamine and dipyridamole infusion to induce myocardial ischemia. In a population of 16 anesthetized open-chest swine, a coronary artery stenosis sufficient to abolish the hyperemic response to a 15-second total occlusion was created. Heart rate, systolic blood pressure, and dP/dt were recorded. Myocardial segment shortening was determined by sonomicrometry in all animals. In a subset of seven animals regional myocardial blood flow was measured by injection of radiolabeled microspheres. Dipyridamole was infused according to a high-dose protocol. After a washout period and reestablishment of a baseline state, dobutamine was infused incrementally. There was no significant difference between the baseline states. Dipyridamole did not affect heart rate but did significantly decrease blood pressure and rate-pressure product. Myocardial segment shortening decreased in the ischemic zone by 0.07 +/- 0.08 (p = 0.004). Dobutamine infusion significantly increased heart rate, blood pressure, and rate-pressure product. Myocardial segment shortening in the ischemic zone decreased by 0.17 +/- 0.09 (p < 0.001). Dobutamine decreased blood flow in the ischemic zone relative to baseline. Both dobutamine and dipyridamole infusion resulted in myocardial ischemia. The magnitude of the ischemic response is greater for dobutamine than for dipyridamole.

Experimental acute hypoxia in healthy subjects: evaluation of systolic and diastolic function of the left ventricle at rest and during exercise using echocardiography

To clarify whether or not systolic and diastolic function of the human left ventricle (LV) were decreased during acute hypoxia, at rest and with exercise, 14 healthy male volunteers [age 25.9 (SD 3.0) years, height 182.9 (SD 7.1) cm, body mass 75.9 (SD 6.9)kg] were examined using M-mode and 2D-mode echocardiography to determine the systolic LV function as well as Doppler-echocardiography for the assessment of diastolic LV function on 2 separate test days. In random order, the subjects breathed either air on 1 day (N) or a gas mixture with reduced oxygen content on the other (H; oxygen fraction in inspired gas 0.14). Measurements on either day were made at rest, several times during incremental cycle exercise in a supine position (6-min increments of 50 W, maximal load 150 W) and in 6th min of recovery. Corresponding measurements during N and H were compared statistically. Arterial O2 tension (PaO2) was normal on N-day. All subjects showed a marked acute hypoxia at rest [PaO2, 54.5 (SD 4.6) mmHg], during exercise and recovery on H-day. The latter was associated with tachycardia compared to N-day. All echocardiographic measurements at rest were within the limits of normal values on both test days. Ejection time, end-systolic and end-diastolic left ventricular dimensions as well as the thickness of left posterior wall and of interventricular septum showed no statistically significant influence of H either at rest or during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of coronary artery disease with upright bicycle exercise echocardiography

This study examined the advantages and limitations of upright bicycle exercise echocardiography in the evaluation of a large series of patients with known or suspected coronary artery disease. The study population consisted of 309 patients (231 men, mean age 57 +/- 11 years) who underwent exercise echocardiography within 8.5 +/- 16.1 days of coronary angiography. All stress electrocardiographic, echocardiographic, and angiographic data were reinterpreted in a blinded manner by the investigators. No patient was excluded because of poor echocardiographic image quality. Wall motion was analyzed at baseline, peak exercise, and immediately after exercise with a 16-segment model, and a regional wall motion score index was calculated at each stage. Abnormalities were ascribed to the distribution of the three coronary arteries and correlated with qualitative angiography. There were 126 patients with wall motion abnormalities at rest and 211 (75%) with coronary artery disease. The stress electrocardiogram (ECG) was negative in 61, positive in 144, and nondiagnostic in 104, yielding a sensitivity of 40% and a specificity of 89%. Echocardiography was normal in 76 of 98 patients without coronary disease (78% specificity) and abnormal in 193 of 211 patients with disease (91% sensitivity). Sensitivity was higher among patients with multivessel disease compared with those with single vessel disease (95% versus 86%, respectively, p = 0.03). Among patients with normal wall motion at rest (n = 183), sensitivity was 83% and specificity was 84%. Of the 104 patients with a nondiagnostic stress ECG, echocardiography correctly identified 95% of those with coronary disease and 75% of those without disease. Among 82 patients with a wall motion abnormality at rest, an additional exercise-induced wall motion abnormality developed in 32 of 46 patients (70%) with multivessel disease and seven of 32 (22%) with single-vessel disease. Overall, echocardiography detected 258 of 392 (66%) individual coronary lesions. Accuracy was higher for lesions in the left anterior descending and right coronary arteries (both 79%) compared with the left circumflex artery (36%, p < 0.001). In conclusion, upright bicycle exercise echocardiography is an accurate technique for the evaluation of patients with known or suspected coronary artery disease and is especially valuable in patients with a nondiagnostic stress ECG. The test provides supplemental information on the extent and location of coronary lesions and is useful in patients with and without prior myocardial infarction.

Simultaneous transesophageal two-dimensional echocardiography and atrial pacing for detecting coronary artery disease

This study describes a new technique for assessing wall motion abnormalities, combining transesophageal echocardiography (TEE) and transesophageal atrial pacing in 71 patients. Stable capture was reached in 70 patients (99%). In 3 patients (4%) pacing was discontinued prematurely because of discomfort. TEE during pacing was performed in 52 patients with and in 18 patients without coronary artery disease (CAD). In 43 of 52 patients with CAD, regional wall motion abnormalities occurred (sensitivity 83%). No wall motion abnormalities occurred in 17 of 18 patients without CAD (specificity 94%, positive predictive value 98%). Wall motion abnormalities related to another vascular region were observed in 17 of 22 patients with previous myocardial infarction (sensitivity 77%, specificity 100%, positive predictive value 100%). Simultaneous 12-lead electrocardiography during atrial pacing was performed in 57 patients and yielded positive results in 21 of 40 patients with (sensitivity 52%) and in 3 of 17 patients without (specificity 82%, positive predictive value 88%) CAD. Exercise stress testing was performed in 66 patients. Twenty-four of 48 patients with CAD had a positive exercise electrocardiogram (sensitivity 50%); a false-positive exercise electrocardiogram was observed in 3 of 18 patients (specificity 83%, positive predictive value 89%). It is concluded that TEE during transesophageal atrial pacing is a feasible and promising alternative technique for the assessment of CAD, with a higher sensitivity than simultaneous 12-lead and exercise electrocardiography.

Stress echocardiography versus radionuclide stress techniques

The different modalities of stress echocardiography and stress thallium-201 imaging have comparable sensitivity, specificity, and overall predictive accuracy in the diagnosis and prognosis of coronary artery disease. They are also comparable in the assessment and follow-up of patients treated with thrombolytic therapy or who have undergone percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery. Stress radionuclide ventriculography has a lower sensitivity and specificity as compared to stress echocardiography and stress thallium. Dipyridamole thallium has a higher sensitivity as compared to dipyridamole echocardiography in the diagnosis and prognosis of coronary artery disease. New techniques such as dobutamine echocardiography, adenosine stress thallium-201, and adenosine echocardiography have individually shown high sensitivities, specificities, and accuracy. However, further studies are needed on their comparative value. The major advantages of stress echocardiography over radionuclide stress techniques are: lack of radiation exposure; less expense; less time consumption; less personnel required; and greater availability. Its major disadvantage, however, is the inability to obtain adequate studies in all patients.

Exercise as a coronary protective factor

Exercise has multiple beneficial actions, both in normal subjects and in patients with coronary artery disease, which can be cardioprotective. Apart from reducing known risk factors and protecting against their deleterious effects, exercise also reduces the risk of coronary artery disease by increasing cardiovascular fitness. The exact contribution of each of these mechanisms in reducing coronary artery disease morbidity and mortality is unclear. Although fitness may be desirable, much of the cardioprotection can be achieved through increased leisure time and recreational physical activity. The risk-benefit ratio is very much in favor of moderate intensity exercise. Even in the absence of a controlled trial, the available evidence suggests that efforts to encourage physical activity are justified.

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

The diagnostic use of exercise echocardiography has been widely reported. However, transthoracic exercise echocardiography is inadequate in up to 20% of patients because of poor image quality related to exercise. In an attempt to overcome these limitations, a system was developed in which transesophageal echocardiography is combined with simultaneous transesophageal atrial pacing by means of the same probe. In a prospective study, transesophageal echocardiography was performed before, during and immediately after maximal atrial pacing in 50 patients with suspected coronary artery disease. Results of transesophageal stress echocardiography were considered abnormal when new pacing-induced regional wall motion abnormalities were observed. Correlative routine bicycle exercise testing was carried out in 44 patients. Cardiac catheterization was performed in all patients. The success rate in obtaining high quality diagnostic images was 100% by transesophageal echocardiography. All nine patients without angiographic evidence of coronary artery disease had a normal result on the transesophageal stress echocardiogram (100% specificity). Thirty-eight of 41 patients with coronary artery disease (defined as greater than or equal to 50% luminal diameter narrowing of at least one major vessel) had an abnormal result on the transesophageal stress echocardiogram (93% sensitivity). The sensitivity of the technique for one, two or three vessel disease was 85%, 100% and 100%, respectively, compared with 44%, 50% and 83%, respectively, for bicycle exercise testing; the 12 lead electrocardiogram (ECG) during rapid atrial pacing showed a sensitivity of 25%, 64% and 86%, respectively. Thus, rapid atrial pacing combined with simultaneous transesophageal echocardiography is a highly specific and sensitive technique for the detection of coronary artery disease. Ischemia-induced wall motion abnormalities were detected earlier than observed ECG changes. The technique appears to be particularly suited to patients who are unable to perform an active stress test or those with poor quality transthoracic echocardiograms.

Atrial volume in cirrhosis: relationship to blood volume and plasma concentration of atrial natriuretic factor

Increased blood volume, atrial size, and plasma concentration of atrial natriuretic factor are described in cirrhosis. Their interrelationships were examined in 17 men with alcoholic liver disease, 7 with and 10 without ascites. Atrial size was determined by two-dimensional echocardiography. Patients with cirrhosis had significantly increased left atrial volume and plasma concentration of atrial natriuretic factor when compared with normal male subjects. Right atrial volume was normal in patients with cirrhosis, as was left ventricular function. Patients with ascites had significantly increased blood volume and plasma atrial natriuretic factor concentration compared with patients without ascites. Left and right atrial volume did not differ between the groups. Blood volume correlated significantly with left atrial volume, which correlated significantly with plasma concentration of atrial natriuretic factor. Cirrhosis is associated with related increases in vascular volume, left atrial size, and plasma atrial natriuretic factor concentration. Increased blood volume probably contributes to the increase in left atrial volume, which is in turn one reason for the elevation of plasma atrial natriuretic factor concentration.

Altered left ventricular volume and ejection fraction responses to supine dynamic exercise in athletes

Two-dimensional echocardiography was used to determine the responses of left ventricular volumes, ejection fraction and segmental left ventricular motion to supine dynamic exercise in 22 professional athletes, comparing these responses with those in 22 age- and gender-matched healthy untrained individuals. End-systolic volume was significantly greater at rest and during exercise in the athletes (50 +/- 6 versus 29 +/- 4 ml and 40 +/- 5 versus 17 +/- 4 ml, respectively, p less than 0.001 for both). It decreased during exercise in all the untrained subjects, but did not change or increased in nine athletes (41%). End-diastolic volume was greater in the athletes at rest (143 +/- 12 versus 98 +/- 9 ml) and during exercise (157 +/- 14 versus 121 +/- 13 ml, p less than 0.01 for both). It increased in all the untrained subjects, but decreased or did not change in six athletes (27%). Ejection fraction was significantly lower in the athletes at rest and during exercise (65 +/- 4% versus 70 +/- 5% and 73 +/- 5% versus 86 +/- 5%, p less than 0.01 and 0.001, respectively); the values augmented normally in all the untrained subjects, but increased only by less than 5% units, did not change or decreased in nine athletes (41%). Eight athletes (36.5%) failed to demonstrate the expected symmetric hyperkinetic wall motion changes during exercise, which were seen in all the untrained subjects. No correlation was found between atypical responses to exercise and electrocardiographic patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertension and sports activities: institutional experience

Findings of 185 patients and 271 control subjects are presented for the assessment of work capacity in hypertensive individuals (primary hypertension); an attempt at classification by hypertensive stage is seen as an essential presupposition. The subdivision into three stages recommended by the Experts' Commission of the WHO places the effects of hypertension on the organism, especially on the heart, in the focal point. This appears justified from a prognostic, pathophysiological, and therapeutic point of view. Hemodynamics in the examined patients undergo increasing impairment in relation to the stage of hypertension with a decrease in maximum cardiac index and work capacity and an increase in myocardial oxygen requirement. Initially, only the diastolic cardiac function is impaired; however, in advanced stages, the systolic function of the heart is impaired as well. Evaluation of work capacity is usually possible from a cardiac point of view by means of noninvasive echocardiographic and spiroergometric methods. The mass/volume ratio of the left cardiac ventricle and the relationship between left ventricular muscle mass (or volume) and work capacity are especially important. Both experience characteristic changes depending on the stage of hypertension and thus permit precise determination of work capacity, progress controls, and delineation from physiological cardiac hypertrophy (athletic heart).

Usefulness of immediate postexercise two-dimensional echocardiography in post-myocardial infarction patients without ischemic ECG changes in stress testing: comparison with radionuclide angiography

Of 38 post-myocardial infarction (MI) applicants for a cardiac rehabilitation program, 17 (45%) did not have ischemic ECG changes in exercise testing. Ten (59%) of these 17 patients had echocardiographic wall motion abnormalities at rest. Immediate postexercise two-dimensional echocardiography demonstrated exercise-induced changes in 8 (47%) patients (2 with normal and 6 with abnormal results from rest studies). The comparative radionuclide (RNA) examinations showed that there were 6 patients with abnormal findings from rest RNA; exercise-induced changes were detected in 7 (44%) of 16 patients (3 with normal and 4 with abnormal results from rest RNA tests). Statistical analyses, using RNA as reference point, revealed that the total correctly diagnosed cases for the echocardiographic rest studies was 13/17 (77%) and for the exercise studies, 13/16 (81%). The negative predictive values were 7/7 (100%) and 7/8 (88%), respectively. The corresponding positive predictive values were 6/10 (60%) and 6/8 (75%). The same pattern was observed when each segment (septal, apical, and posterolateral) was evaluated separately. The authors conclude that in post-MI patients with a negative stress test, the efficacy of postexercise echocardiography equals that of RNA in the identification of additional patients with ischemia.

Left ventricular exercise echocardiographic abnormalities in apparently healthy men with exertional hypotension

Of a total of 1,435 healthy untrained asymptomatic individuals referred for a routine periodic checkup, 23 subjects with exertional hypotension on upright bicycle stress testing were identified. All were male. This study assesses by means of echocardiography the responses to exercise of left ventricular (LV) volumes, ejection fraction and segmental LV contractility in these subjects. Exertional hypotension was defined as a decrease in systolic blood pressure to below the resting value at the end of stress test. Supine systolic blood pressure after exercise was significantly greater in the control group than in the study group (179 vs 121 mm Hg, respectively; p less than 0.001); there was no significant intra- or intergroup difference in the resting values. In the study group end-systolic volume was 37 ml at rest and 35 ml after exercise; ejection fraction varied from 65% at rest to 63% after exercise. The sex- and age-matched control group with a normal systolic blood pressure response to exercise showed a shift from 35 to 23 ml and 65 to 77%, respectively (p less than 0.01 and 0.001). Ejection fraction correlated well with radionuclide angiography values. Exertional hypotension was noted after both upright and supine exercise. The pattern of regional wall motion remained unchanged or was hypokinetic in 87% of the subjects; only 13% presented the normally expected hyperkinesia after exercise. This study demonstrates that exertional hypotension is accompanied by an abnormal LV performance.

Diagnostic accuracy of 2-D echocardiography for detection of exercise-induced wall motion abnormalities in patients with coronary artery disease: comparison to biplane cineventriculography

To determine the accuracy of two-dimensional echocardiography (2-D echo) for assessment of exercise-induced wall motion abnormalities in patients with coronary artery disease, the results of stress echocardiography were compared with exercise cineventriculography. In 56 consecutive patients, biplane cineventriculography at rest and immediately after supine bicycle exercise was performed. Cross-sectional echo was obtained using the apical two- and four-chamber-views for left ventricular imaging under identical conditions. In 6 of the 56 patients 2-D echo, in 8 patients cineventriculogram, and in 2 patients both methods were of inadequate quality at rest or during exercise. Of the remaining 40 patients, 34 had coronary artery disease. Local wall motion in 360 wall segments from these patients was analyzed. In 49 segments (14%) in 24 of these patients exercise-induced ischemic wall motion abnormalities were evident during cineventriculography. Only 24 of these 49 asynergies (49%) were also recognized by 2-D echo. Using cross-sectional echocardiography, ischemia-related wall motion abnormalities were best detected septal, whereas apical asynergies were identified in only 3 of 12 segments (25%). Thus, the clinical value of exercise 2-D echo as a screening method in patients suspected of having coronary artery disease is limited and restricted to patients where excellent visualization of the left ventricular endocardium is possible.

[Value of 2-D echocardiography in the detection of stress-induced wall-motion abnormalities in coronary heart disease--a comparison with biplane cineventriculography]

To determine the accuracy of echocardiography in assessment of exercise-induced wall motion abnormalities, the results of stress-echocardiography were compared with exercise-cineventriculography. In 56 consecutive patients biplane cineventriculography at rest and immediately after supine bicycle exercise was performed. Cross-sectional echocardiography was obtained using the apical 2- and 4-chamber view for LV imaging under identical exercise conditions. In 6 of the 56 patients 2-D echo, in 8 patients LV-angio, and in 2 patients both methods were of inadequate quality during exercise. Thus, in 40 patients (34 patients had coronary artery disease) local wall motion of 360 wall segments was analysed. 49 segments (14%) of 24 patients showed exercise-induced ischemic wall motion abnormalities during cineventriculography. Only 24 of these 49 asynergics (49%) were also detected by 2-D-echo. Using cross-sectional echocardiography, ischemia related wall motion abnormalities were best detected laterally and septaly, whereas apical asynergies were identified in 3 of 12 segments only. Thus, the clinical value of exercise 2-D echo as a screening method in patients suspected to have coronary artery disease is limited and restricted to patients with excellent visualization of the left ventricular endocardium.

High dose dipyridamole echocardiography test in effort angina pectoris

The dipyridamole echocardiography test (intravenous dipyridamole with two-dimensional echocardiographic monitoring) was performed in 93 patients with effort chest pain and in 10 control subjects. The test was considered positive when regional asynergy appeared after dipyridamole administration. When negative at the low dose (0.56 mg/kg body weight in 4 minutes), the test was repeated on a different day with a higher dose (0.84 mg/kg in 10 minutes). All 93 patients underwent coronary arteriography; 72 of them had significant (greater than 70% luminal reduction) coronary artery disease. Thirty-eight of the 93 patients had a positive low dose dipyridamole echocardiography test; 15 other patients with a negative low dose test had a positive high dose test. All 53 patients with a positive test had significant coronary artery disease; 12 of them had a negative exercise stress test. In relation to the presence of coronary artery disease, the dipyridamole echocardiography test had an overall specificity higher than that of the exercise stress test (100 versus 71%) and a similar overall sensitivity (74 versus 69%). The dipyridamole echocardiography test is feasible in all patients with a good baseline echocardiogram. It detects the site of apparent ischemia more precisely than does an exercise stress test, and can unmask electrocardiographically silent ischemia. If performed in patients with a negative low dose dipyridamole echocardiography test, the high dose test adds sensitivity (probably by achieving maximal dilation in patients in whom the low dose is only partially effective), without any loss in specificity and with no apparent increase in risk.

Quantitative analysis of segmental wall motion during maximal upright dynamic exercise: variability in normal adults

Twenty-five healthy adults underwent subcostal-view, four-chamber two-dimensional echocardiographic examination while upright at rest and at the peak of maximal bicycle exercise. The purpose of the study was to determine whether the variability in regional left ventricular endocardial motion, previously demonstrated to be present at rest, persisted at peak exercise. The rest and exercise end-diastolic and end-systolic endocardial contours were visually identified, digitized, and divided into 32 radial segments after realignment by the computer. At rest there was similar percent segmental area reduction for the septum (segments 1 to 12) (54 +/- 4%, mean +/- 1 SD), apex (segments 13 to 20) (67 +/- 3%), and lateral wall (segments 21 to 32) (67 +/- 8%). At peak exercise the percent area reduction increased significantly: septum 84 +/- 5%, apex 88 +/- 2%, lateral wall 83 +/- 6% (p less than .001 compared with rest for all areas). However, there was considerable variability in percent area reduction between different radial segments in the same individual. At rest the difference between minimal and maximal percent area reduction within the same individual was 49 +/- 17 percentage units (range 21 to 83) and that at peak exercise was 32 +/- 17 percentage units (range 0 to 66). It is concluded that, because the range of standard deviation of normal endocardial motion and the degree of variability between radial segments in the same healthy individual are significant, qualitatively determined "hypokinesis," as commonly assessed clinically, may be a normal event. However, segmental akinesis or dyskinesis, which occurred rarely at rest and never at peak exercise, must be considered abnormal events.

Effect of isotonic exercise training on left ventricular volume during upright exercise

To determine the changes in left ventricular volume and their time course during exercise we studied 30 runners. Left ventricular end-diastolic and end-systolic volumes were measured from biapical two-dimensional echocardiograms recorded during graded upright bicycle exercise. The validity of this echocardiographic technique was assessed by comparing measurements at rest and exercise with results obtained by gated equilibrium radionuclide angiography in 10 patients with coronary artery disease. Although the absolute volume measurements were lower by echocardiography, ejection fraction was not significantly different and the directional changes in volume during exercise were comparable. In the runners, resting left ventricular end-diastolic volume measurements by echocardiography correlated with their maximum bicycle exercise endurance times (r = .80). Left ventricular end-diastolic volume, stroke volume, and ejection fraction increased during exercise with the most marked changes occurring in the first half of exercise. Systolic blood pressure/end-systolic volume (SBP/ESV) also increased during exercise, but the largest change occurred during the second half of exercise. Left ventricular volumes were larger in the 12 competitive marathon runners (maximum exercise duration greater than or equal to 27 min) as compared with the 18 noncompetitive runners (exercise duration less than or equal to 23 min): resting end-diastolic volume 130 +/- 29 (SD) ml vs 87 +/- 20 ml (p less than .001), respectively. During exercise the competitive runners exhibited a larger increase in end-diastolic volume and the noncompetitive athletes showed a greater increase in SBP/ESV. Therefore, highly trained competitive marathon runners make greater use of the less energy-consuming Frank-Starling mechanism to accomplish high levels of isotonic exercise performance as compared with less well-trained runners.

Clinical use of ultrashort-lived radionuclide krypton-81m for noninvasive analysis of right ventricular performance in normal subjects and patients with right ventricular dysfunction

The ultrashort-lived radionuclide krypton-81m, eluted in 5% dextrose from a bedside rubidium-81m generator, was intravenously infused for rapid imaging of the right-sided heart chambers in the right anterior oblique projection adjusted for optimal right atrioventricular separation. Left-sided heart and lung background was minimized by rapid decay and efficient exhalation of krypton-81m, requiring no algorithm for background correction. A double region of interest method decreased the variability in the assessment of ejection fraction to 5%. In 10 normal subjects, 11 patients with pulmonary hypertension, 4 patients with right ventricular outflow tract obstruction and 4 patients with right ventricular infarction, right ventricular ejection fraction determined by krypton-81m equilibrium blood pool imaging ranged from 14 to 76%. The correlation between these values and those determined by cineangiography according to Simpson's rule was close: r = 0.93 for all data points (p less than 0.001), r = 0.92 for studies at rest (p less than 0.001) and r = 0.93 for exercise studies (p less than 0.001). Exercise-related changes in right ventricular function revealed a disturbed functional reserve with pulmonary hypertension and right ventricular infarction, whereas in compensated right ventricular outflow tract obstruction there was a physiologic increase in ejection fraction with exercise (p less than 0.001). Thus, equilibrium-gated right ventricular imaging using ultrashort-lived krypton-81m is a simple, accurate and reproducible method with potential for serial assessment of right ventricular ejection fraction in a variety of right ventricular anatomic and functional abnormalities, both at rest and during exercise. Advantages of this method include an extremely low radiation dose to patients and clear right atrioventricular separation without the need to correct for background activity.

Echocardiographic assessment of cardiac function in infants and children

Echocardiography has become an established technique for the assessment of cardiac function in infants and children. M-mode echocardiography provides measurements of left ventricular diameter and wall thickness and allows calculation of their rate of change during the cardiac cycle. Left and right ventricular systolic time intervals may be determined from recordings of aortic and pulmonary valve motion. Two-dimensional echocardiographic images may be utilized for the determination of left and right ventricular volume and ejection fraction. Compared with other noninvasive imaging methods, echocardiography is a rapid, safe and inexpensive technique. Moreover, future developments are likely to include improved image processing and computer analysis of two-dimensional images.

Accuracy of absolute left ventricular volumes and cardiac output determined by radionuclide cardiography

We determined left ventricular (LV) volumes and derived variables by gated equilibrium radionuclide imaging at rest and during exercise in 12 patients without valve disease or intracardiac shunts. LV volume was determined as the product of the background-corrected LV count rate and an individual attenuation correction factor divided by the count rate in peripheral blood. Attenuation correction was based on measurement of LV depth within the chest from an initial first pass study in the left lateral view and a linear attenuation coefficient of 0.156 cm-1 determined in phantom studies. The average LV depth was 8.0 cm (range 6.9-9.1) in agreement with an average depth measured by echocardiography of 8.2 cm (6.3-9.4), P much greater than 0.05. The correlation between radionuclide (RC) and simultaneous thermodilution (TD) measurements was for cardiac output (CO): r = 0.95; CO (RC) = 1.00 X CO (TD) + 0.10 1/min with a standard error of the estimate (SEE) of 0.79 1/min; for stroke volume (SV): r = 0.90; SV(RC) = 0.93 X SV (TD) + 5 ml; SEE = 8 ml; for end-diastolic volume (EDV): r = 0.96; EDV(RC) = 1.06 X EDV(TD) -14 ml; SEE = 27 ml; and for end-systolic volume (ESV): r = 0.98; ESV(RC) = 1.05 X ESV (TD) -6 ml; SEE = 20 ml. The interobserver variation, expressed as the coefficient of variation, was for cardiac output 6%, for stroke volume 6%, for end-diastolic volume 4%, and for end-systolic volume 5%. This method permits non-invasive determination of LV volume and total LV output per beat based exclusively on data obtained during radionuclide imaging.

Exercise two-dimensional echocardiography for diagnosis of coronary artery disease

To improve ultrasound images during exercise 2-dimensional echocardiography (2-D echo), a device was developed to hold the transducer and maintain its orientation relative to the heart. The value of this technique in detecting wall motion abnormalities and changes in ejection fraction was evaluated in 54 men undergoing stress test for angina. Thallium-201 scanning, electrocardiography and exercise 2-D echo were recorded concurrently. Technically satisfactory echo studies were obtained in 47 patients (87%). The sensitivity and specificity of exercise echo in the detection of myocardial ischemia as judged by wall motion abnormalities were 100% and 93%, respectively. Sixteen patients with normal thallium scans increased their ejection fraction (EF) estimated by echo (from 52 +/- 1% at rest to 67 +/- 1% at maximal exercise, p less than 0.001); all showed an increase of 5% or more. In contrast, 11 patients who had reversible thallium scan defects showed a consistent decrease in EF (from 53 +/- 2% at rest to 43 +/- 2% during exercise, p less than 0.001); 20 patients with irreversible thallium scan defects showed no specific trend in the EF (48 +/- 2% at rest and 50 +/- 2% during exercise, difference not significant). Changes in heart rate and blood pressure did not distinguish the 3 groups of patients. Our technique of exercise 2-D echo may be useful for detecting wall motion abnormalities and EF changes during exercise and possibly enhance the sensitivity of thallium scanning in the noninvasive diagnosis of coronary artery disease.

Stress echocardiography with transesophageal atrial pacing: preliminary report of a new method for detection of ischemic wall motion abnormalities

We performed two-dimensional echocardiography in 19 patients with significant coronary artery disease and in six normal volunteers at rest and during transesophageal atrial pacing. Technically adequate resting echocardiograms were obtained in 18 of the 19 patients and in all six normal volunteers. In two subjects, atrial capture was not possible, and in one subject, discomfort from the pacing at the beginning of the study precluded its completion. In all subjects (n = 21) who completed the protocol satisfactory two-dimensional echocardiograms were obtained during pacing. Wall motion was normal at rest and during atrial pacing in five normal volunteers. New transient wall motion abnormalities developed in 13 of the 16 patients during pacing. Twelve of the 13 patients had significant coronary lesions in the coronary arteries supplying the abnormal wall segment. Only three of the patients developed significant ST segment depression during pacing. We conclude that stress echocardiography with transesophageal atrial pacing is safe and practical and can be used in patients who cannot perform dynamic exercise, this technique can detect ischemic segmental wall motion abnormalities corresponding to the distribution of coronary arterial obstruction, and the technique provides high-quality echocardiographic images during stress and thus may expand the usefulness of resting two-dimensional echocardiography in patients who have ischemic heart disease.

Plasma catecholamines, beta-adrenergic receptors, and isoproterenol sensitivity in endurance trained and non-endurance trained volunteers

Six male non-endurance trained subjects (S) and six marathon runners (M) underwent graded treadmill exercise (T) and isoproterenol stimulation (I; 2 and 4 microgram X min-1). beta-adrenergic receptor density was additionally determined as the amount of 3H-Dihydroalprenolol (DHA) specifically bound on intact polymorphonuclear leucocytes. Heart rate, VO2 uptake, lactate, plasma noradrenaline, and adrenaline were estimated during T. Heart rate, stroke volume, cardiac output, as well as lactate, glucose, free fatty acids (FFA), and glycerol levels in the blood were determined during I. M showed the known training-dependent responses during T, such as lower heart rates, lactate levels, and plasma catecholamines at identical work loads, as well as higher VO2 max than S. I-induced cardiac output increase was quite similar in both groups. Stroke volume, however, increased significantly in M and stayed constant in S. Lactate decreased (S), glucose increased significantly (M), glycerol increased similarly in both groups, FFA rise was less marked in S. I-induced stroke volume response (I) may be indicative of a more economic regulation of heart work in M than S. Lactate decrease and less marked FFA increase, as observed in S, may be the result of a somewhat higher cardiac energy demand, dependent on less economic heart work. Higher DHA-binding as observed in M, as well as stroke volume response and glucose increase, may be indicators of a training-dependent rise in sensitivity to catecholamines. The unsolved question is, however, to what extent beta-receptor responses in intact blood cells are significant for receptor behavior in other organs.

Increased left ventricular emptying at maximal exercise after reduction in afterload

Twelve healthy men were studied by M mode echocardiography during exercise to investigate the effect of afterload reduction on left ventricular function at maximal exertion. They performed two maximal exercise bicycle tests 4 hr apart while in the semisupine position and were given 20 mg nifedipine sublingually 30 min before the second test. During the first test end-systolic dimension decreased (p less than .01) and fractional shortening increased from rest to peak exercise (p less than .01), while end-diastolic dimension did not change significantly. At maximal exercise systolic blood pressure was lower after nifedipine than in the preceding control test (202 +/- 10 [mean +/- SD] vs 212 +/- 14 mm Hg; p less than .01), while heart rate was not significantly changed (168 +/- 15 vs 162 +/- 13 beats/min). End-systolic dimension was lower (25.6 +/- 3.3 vs 28.8 +/- 4.2 mm; p less than .01) and fractional shortening higher (50.7 +/- 6.0% vs 45.3 +/- 7.0%; p less than .01) while end-diastolic dimension was unchanged (52.3 +/- 1.9 vs 52.4 +/- 2.6 mm). Our data indicate increased left ventricular emptying at maximal exercise after nifedipine, most probably due to reduction in afterload.

Exercise subcostal two-dimensional echocardiography: a new method of segmental wall motion analysis

This study determines the effectiveness of the subcostal view 2-dimensional (2-D) echocardiogram in providing images of left ventricular wall motion at rest and during symptom-limited upright bicycle exercise, and compares 2-D echocardiographic regional wall motion analysis with first-pass radionuclide angiography. Diagnostic-quality subcostal 2-D echocardiograms at rest were obtained in 95% of unselected persons studied (16 of 17 normal subjects and 23 of 24 patients who had had myocardial infarction [MI] ). All who had adequate studies at rest had diagnostic-quality maximal exercise studies. Segmental wall motion at rest and exercise determined by 2-D echocardiography correlated well with radionuclide angiography in both the normal and post-MI groups. The chi-squared values for the 3 segments analyzed were: anterior 52 (p less than 0.001), apical 56 (p less than 0.001) and inferior 37 (p less than 0.001). It is concluded that subcostal view 2-D echocardiography at rest and at the peak of symptom-limited upright bicycle exercise is a feasible and accurate noninvasive method for the analysis of segmental left ventricular function.

Exercise two-dimensional echocardiography: a technique for improving ultrasound images during exercise stress

A system of exercise stress echocardiography was developed in which, during exercise on a bicycle ergometer in a semirecumbent position, the echocardiographic transducer is held by a special device which maintains a relatively constant position between the transducer and the heart. The system was evaluated in 21 healthy subjects and technically satisfactory studies were obtained in 20. In these, the resolution and relative position of the cardiac image remained stable throughout exercise. Blood pressure and heart rate increased appropriately with our protocol with supine exercise; 95% of the subjects reached 90% of their predicted maximum heart rate for age. Ejection fraction measured by echocardiography increased from 54 +/- 1% to 70 +/- 1%. It is concluded that the use of our transducer-holding device in subjects performing exercise in the supine position significantly improves ultrasonic image quality and should enhance the clinical usefulness of exercise stress echocardiography.

Detection of coronary artery disease with exercise two-dimensional echocardiography. Description of a clinically applicable method and comparison with radionuclide ventriculography

Two-dimensional echocardiography (2-D echo) was performed in 73 patients evaluated for coronary artery disease (CAD) and in four normal volunteers before and immediately after a maximal treadmill exercise test. Diagnostic images were obtained from the apical and parasternal windows. In 17 patients with normal coronary arteriograms, ejection fraction (EF) increased from 66 +/- 9% (+/- SD) at rest to 73 +/- 8% after exercise (p less than 0.001), while in 56 patients with proved CAD, EF fell from 56 +/- 13% at rest to 53 +/- 16% after exercise (p less than 0.01). The sensitivity of postexercise 2-D echo for detecting CAD (based on abnormal EF response and/or regional dyssynergy) was 91% (51 of 56 patients) and the specificity was 88% (15 of 17). Sensitivity for one-, two- and three-vessel disease was 64% (seven of 11), 95% (20 of 21) and 100%, respectively. Patients with multivessel disease showed a significant fall in a wall motion score index, from 0.79 +/- 0.25 to 0.63 +/- 0.26. Exercise radionuclide ventriculography (RNV) was also performed in 41 of the subjects (17 normals and 24 CAD patients) on a bicycle ergometer. The overall sensitivity of 2-D echo in this subgroup was 92%, compared with 71% for RNV. The sensitivity of 2-D echo for one-vessel disease (n = 4) was 50%, that for two-vessel disease (n = 12) was 100% and that for three-vessel disease (n = 12) was 100%. Respective values for RNV were 0%, 80% and 90%. The specificity of 2-D echo was 88% and that of RNV was 82%. A significantly higher peak heart rate response was observed on the treadmill than on the bicycle ergometer in both CAD patients and normal subjects. We conclude that postexercise 2-D echo is a clinically applicable technique for the diagnosis and evaluation of CAD patients and compares favorably with exercise RNV.

Advances in clinical management of acute myocardial infarction in the past 25 years

The management of acute myocardial infarction in the past 25 years has emerged from a state of masterful inactivity to one of intensive care based on a new discipline of aggressive management. This has increased the chances of survival of the victim of infarction and could well be one of the major reasons for the decline in mortality due to coronary heart disease in the United States since 1968. Because resuscitative techniques must be instituted within 4 minutes after the onset of cardiac arrest, the attendant nurse had to learn the new emergency lifesaving techniques and assume a crucial role as a physician's assistant. The various stages in the evolution of coronary care discipline began with cardiopulmonary resuscitation and were followed by pacemaker application, arrhythmia prophylaxis and insertion of pulmonary venous flow-directed catheters and arterial lines that permit monitoring and control of ventricular filling pressures. Other developments in better management of the failing heart have included methods to salvage jeopardized myocardium, strategies for the prevention of sudden death, the application of revascularization techniques after acute coronary occlusion and new noninvasive computerized technology to provide enhanced contrast images of cardiac perfusion that can be directly integrated with measurement of function.

Mechanism of paradoxic pulse in bronchial asthma

To elucidate the mechanism of paradoxic pulse in severe bronchial asthma, we performed hemodynamic studies and measured esophageal pressure in nine patients who had status asthmaticus and clinical paradoxic pulse. Two-dimensional echocardiography allowed simultaneous assessment of cyclic changes in right- and left-heart size throughout the respiratory cycle. Esophageal pressure varied from a markedly negative level during inspiration (-24.4 +/- 6.5 cm H2O) to a positive level during expiration (7.6 +/- 6.0 cm H2O). Competition between right- and left-heart chambers for pericardial space during inspiration was suggested by the reduced left ventricular cross-sectional area at end-systole (-24%, p less than 0.01) and end-diastole (-32%, p less than 0.01), the leftward septal shift, and the increased right ventricular internal diameter at end-systole (42%, p less than 0.01) and end-diastole (40%, p less than 0.001). Competition for filling, however, could not entirely account for the paradoxic pulse, for systemic and pulmonary pulse pressures were almost (within one cardiac cycle) in phase: both were minimal at inspiration and maximal at expiration. The increase in impedance to right ventricular ejection is another major factor reducing left ventricular preload at inspiration. This reduction in preload was shown to be the predominant mechanism for the decrease in left ventricular stroke output at inspiration.