Application of tissue Doppler to interpretation of dobutamine echocardiography and comparison with quantitative coronary angiography

Variability of longitudinal strain in left ventricular segments supplied by non-stenosed coronary artery: insights from speckle tracking analysis of dobutamine stress echocardiograms in patients with high coronary risk profile

INTRODUCTION

Although global deformation parameters have been increasingly used for myocardial function analysis, there are sparse data concerning segmental deformation of the left ventricle (LV). Moreover, some studies suggest heterogeneity of strain among LV segments, which may be especially significant during stress echocardiography. We assessed quantitatively regional LV function in the setting of dobutamine stress echocardiography (DSE), to examine differences of longitudinal strain between basal, mid and apical LV segments and to compare variability of regional deformation between rest and the peak stage of DSE.

MATERIAL AND METHODS

Among 250 patients examined by DSE applied for diagnosis of ischemia, a subset of 111 patients without significant coronary stenoses in angiography was selected (68 females, mean age: 60 ±10 years). Systolic longitudinal strain (SLS) in individual LV segments at baseline and the peak stage of DSE was analyzed with speckle tracking echocardiography.

RESULTS

Inhomogeneity of SLS among the LV segments (p < 0.001) was observed at baseline and the peak stage. Dispersion indices were higher at the peak stage of DSE than at baseline (p < 0.001), and the lowest heterogeneity was observed among mid segments. The analysis of changes in SLS during DSE showed SLS reduction in basal and mid-ventricular segments and an increase in apical segments.

CONCLUSIONS

Significant heterogeneity of strain and the opposite direction of the longitudinal strain changes during DSE between apical and basal LV segments were observed. This variability among non-ischemic LV segments ought to be considered in quantification of LV function during DSE.

Combination of single quantitative parameters into multiparametric model for ischemia detection is not superior to visual assessment during dobutamine stress echocardiography

Background

To evaluate if the combination of several quantitative parameters into a mathematical model would enhance the detection of myocardial ischemia during dobutamine stress echocardiography (DSE) when compared to conventional wall motion analysis.

Methods

In a prospective study design 151 patients (age 61.8 ± 9.2) in test group and 105 patients (age 64.0 ± 10.6) in validation group were selected and underwent DSE between January 2008 and December 2012. In all patients coronary angiography was performed within 6-8 weeks from DSE, considering at least one stenosis ≥50 % per patient as significant coronary artery disease (CAD). Results of DSE visual assessment and myocardial velocity, strain and strain rate parameters derived from speckle tracking imaging were imported automatically to an originally created software. A mathematical model calculating prognosis of at least one stenosis per patient and stenosis in separate arteries was constructed.

Results

Myocardial ischemia was visually detected in 60 (39.7 %) and in 58 (54.2 %) patients of the test and validation group, respectively. A total of 76 (50.3 %) patients in the test group and 69 patients (65.7 %) in the validation group had ≥50 % coronary stenosis. Sensitivity and specificity of the mathematical model per patient in the test group were 91.6 % and 86.3 % compared to 76.8 % and 89.0 % of the visual assessment, respectively. However, in the validation group the sensitivity, specificity, positive predictive value and negative predictive value dropped down significantly becoming lower to visual assessment.

Conclusions

Myocardial deformation imaging may potentially replace visual assessment with an automated predictive model for stress-induced ischemia detection. However, a multiparametric mathematical model based on quantitative deformation markers did not demonstrate incremental value to visual assessment of wall motion.

Biventricular function and glycemic load in type 1 diabetic children: Doppler tissue-imaging study

To assess right- and left-ventricular function in children with type 1 diabetes mellitus (DM) as well as correlate cardiac function with diabetes duration and state of metabolic control. The present study included 30 patients with type 1 DM (group 1) and 20 apparently normal children with comparable age and sex as controls (group 2). All children were subjected to detailed history, clinical examination, and routine laboratory investigations, including glycated hemoglobin, as well as conventional echocardiographic and tissue Doppler examination. Children with type 1 DM have impaired diastolic function in both left and right ventricles before the development of systolic dysfunction when assessed with either conventional or tissue Doppler echocardiography. Resting heart rate in diabetic patients showed a significant positive correlation with mitral A flow velocity and a significant negative correlation with mitral and tricuspid E/A ratio. Regarding morphological parameters of the left ventricle, all dimensions and volumes were comparable between diabetic patients and controls; however, a significant positive correlation was found between interventricular septal thickness at diastole (IVSd), interventricular septal thickness at systole (IVSs), and left ventricular posterior wall at systole (LVPWs) and the duration of diabetes. Children with type 1 DM have impaired diastolic function in both left and right ventricles with normal systolic function when assessed with either conventional or tissue Doppler echocardiography.

Quantitative approach using multiple single parameters versus visual assessment in dobutamine stress echocardiography

BACKGROUND

A number of myocardial Doppler-derived velocity, strain myocardial imaging parameters (DMI) and speckle tracking imaging (STI) have been proposed for the quantification of myocardial ischemia during stress echocardiography. The purpose of the study was to identify the best single ultrasound quantitative parameter for prediction of significant coronary stenosis and compare it with visual assessment during dobutamine stress echocardiography (DSE).

METHODS

Prospective analysis included data of 151 patients (age 61.8 ± 9.2) who underwent dobutamine stress echocardiography for known (n = 35) or suspected coronary artery disease (CAD) (n = 36) or symptomatic chest pain (n = 80), excluding patients with previous myocardial infarction. Systolic, post-systolic and diastolic velocities, strain and strain rate parameters were obtained at rest and at peak dobutamine challenge. Derivative markers as E'/A' ratio, post-systolic index and changes from rest to stress were calculated (98 parameters overall, predominantly longitudinal). Coronary angiography was chosen as reference method considering at least one stenosis ≥70% per patient as significant CAD. The predictive value of quantitative parameters and wall motion score index (WMSI) was obtained using logistic regression and ROC analysis.

RESULTS

The value of single parameters discriminated as independent predictors of CAD appeared to be modest (area under the curve [AUC] ranged from 0.63 to 0.72 for 16 PW-DMI, 12 CC-DMI and 12 STI markers), comparing to AUC of WMSI 0.88. Sensitivity, specificity and accuracy of visual DSE evaluation was 82.4% (95%CI 77.4%; 85.2%), 92.6% (95%CI 83.4%; 97.5%) and 86.0% (95%CI 79.5%; 89.6%), respectively, Youden index 0.75. Sensitivity, specificity and accuracy of single predictors ranged from 40.0% to 93.3% (95% CI 22.7%; 99.2%), from 34.2% to 88.7% (95% CI 25.6%; 94.1%) and from 45.8% to 80.0% (95% CI 37.5%; 87.2%) respectively, Youden index ranged from 0.20 to 0.52.

CONCLUSIONS

Multiple single quantitative parameters showed limited predictive ability to identify significant coronary artery stenosis. Visual assessment of DSE appears to be more accurate than single velocity and strain/strain rate markers in the diagnosis of CAD.

Sufentanil preserves hemodynamics and left ventricular function in patients with ischemic heart disease

OBJECTIVE

Sufentanil has been reported to provide stable hemodynamics similar to other opioids. However, it has not been reliably established whether this stability can be attributed only to Sufentanil and translates into fully preserved left ventricular (LV) function. The purpose of this study was to evaluate the effect of Sufentanil on hemodynamics and LV systolic and diastolic function using invasive monitoring and echocardiography in patients with ischemic heart disease.

METHODS

Prospective observational study of thirty patients acting as their own control undergoing echocardiographic imaging before and after bolus Sufentanil 1.5-2.0 μg/kg. Full invasive hemodynamic monitoring was established before Sufentanil administration. Global LV systolic function was evaluated with a global longitudinal peak systolic strain (GLPSS) by speckle tracking ultrasound; systolic displacement by tissue tracking (TT) and diastolic function was evaluated using Doppler tissue imaging and pulse wave Doppler.

RESULTS

Hemodynamic monitoring showed a minor decline in systolic blood pressure from 159 to 154 mmHg (P=0.046). No changes were observed in the cardiac index, stroke volume index and heart rate. An unchanged TT score index (9.9 vs. 10.2 mm, P=0.428) and GLPSS (14.3 vs. 14.5%, P=0.658) indicated preserved LV global systolic function and unchanged E'/A' (0.95 vs. 0.89, P=0.110) and E/E' ratio (15.4 vs. 14.9, P=0.612) indicated unchanged diastolic function.

CONCLUSION

Sufentanil preserves hemodynamic parameters as well as echocardiographic indices of LV systolic and diastolic function in patients with ischemic heart disease (IHD).

Ketamine reduce left ventricular systolic and diastolic function in patients with ischaemic heart disease

OBJECTIVE

Ketamine may be followed by a general increase in haemodynamics and oxygen consumption, which may be of concern in patients with ischaemic heart disease. The purpose of this study was to evaluate the effect of ketamine on left ventricular (LV) systolic and diastolic function by different modalities of echocardiography and tissue Doppler imaging in patients with ischaemic heart disease.

METHODS AND RESULTS

Prospective observational study of 11 patients acting as own control based on echocardiographic imaging before and after bolus ketamine 0.5 mg/kg. Simpson's 2 D-volumetric method was used to quantify left ventricular volume and ejection fraction. General global LV deformation was assessed by Speckle tracking ultrasound, systolic LV longitudinal displacement was assessed by Tissue Tracking score index and the diastolic function was evaluated from changes in early-(E') and atrial (A') peak velocities during diastole. Average heart rate (34%) and blood pressure (35%) increased significantly after ketamine (P<0.0001). Mean tissue tracking score index decreased from 11.2 ± 2.3 to 8.3 ± 2.6 (P=0.005) and Global Speckle tracking 2D strain from 17.7 ± 2.7 to 13.7 ± 3.6 (P=0.0014) indicating a decrease in LV global systolic function. The E'/A' ratio decreased from 1.11 ± 0.43 to 0.81 ± 0.46 (P=0.044) indicating impaired relaxation.

CONCLUSION

Different modalities of echocardiography in combination with tissue Doppler indicate both diminished systolic and diastolic function after ketamine administration in patients with ischaemic heart disease.

Exercise echocardiography

Exercise echocardiography has been used for 30 years. It is now considered a consolidated technique for the diagnosis and risk stratification of patients with known or suspected coronary artery disease (CAD). Of the stress echocardiography techniques, it represents the first choice for patients who are able to exercise. Given that the cost-effectiveness and safety of stress echocardiography are higher than those of other imaging techniques, its use is likely to be expanded further. Recent research has also proposed this technique for the evaluation of cardiac pathology beyond CAD. Although the role of new technology is promising, the assessment of cardiac function relies on good quality black and white harmonic images.

Relationship between post-systolic motion during dobutamine stress echocardiography and functional recovery of myocardium after successful percutaneous coronary intervention

BACKGROUND AND OBJECTIVES

Doppler myocardial imaging (DMI) has been suggested as a method of quantifying inducible ischemia during dobutamine stress echocardiography (DSE). Post-systolic motion (PSM) detected by DMI is related to peri-infarct ischemia during DSE. We hypothesized that PSM during DSE would predict recovery of dysfunctional myocardium after successful percutaneous coronary intervention (PCI).

SUBJECTS AND METHODS

Thirty patients with dysfunctional myocardium in the left anterior descending coronary artery (LAD) territory were divided into two groups according to improvement of wall motion score index (WMSI) in the LAD territory at 6 months after successful PCI of the LAD. DMI was evaluated in the LAD territory during DSE. Fifteen patients showed improved WMSI (1.42+/-0.39) while the other 15 had unchanged WMSI (1.75+/-0.46) 1 month after PCI. Myocardial velocity was measured in the mid-septal, apico-septal, and basal anterior segments of the LAD artery territory. PSM was defined as a positive wave appearing after the curve of systolic ejection had reached the zero line.

RESULTS

Although there was no difference between resting PSMs in both groups, PSM during DSE was significantly higher in the improved WMSI group than in the WMSI group where it was unchanged.

CONCLUSION

PSM during DSE predicts recovery of dysfunctional myocardium after successful PCI.

The ischemic preconditioning effect of adenosine in patients with ischemic heart disease

INTRODUCTION

In vivo and in vitro evidence suggests that adenosine and its agonists play key roles in the process of ischemic preconditioning. The effects of low-dose adenosine infusion on ischemic preconditioning have not been thoroughly studied in humans.

AIMS

We hypothesised that a low-dose adenosine infusion could reduce the ischemic burden evoked by physical exercise and improve the regional left ventricular (LV) systolic function.

MATERIALS AND METHODS

We studied nine severely symptomatic male patients with severe coronary artery disease. Myocardial ischemia was induced by exercise on two separate occasions and quantified by Tissue Doppler Echocardiography. Prior to the exercise test, intravenous low-dose adenosine or placebo was infused over ten minutes according to a randomized, double blind, cross-over protocol. The LV walls were defined as ischemic if a reduction, no increment, or an increment of < 15% in peak systolic velocity (PSV) was observed during maximal exercise compared to the baseline values observed prior to placebo-infusion. Otherwise, the LV walls were defined as non-ischemic.

RESULTS

PSV increased from baseline to maximal exercise in non-ischemic walls both during placebo (P = 0.0001) and low-dose adenosine infusion (P = 0.0009). However, in the ischemic walls, PSV increased only during low-dose adenosine infusion (P = 0.001), while no changes in PSV occurred during placebo infusion (P = NS).

CONCLUSION

Low-dose adenosine infusion reduced the ischemic burden and improved LV regional systolic function in the ischemic walls of patients with exercise-induced myocardial ischemia, confirming that adenosine is a potential preconditioning agent in humans.

Factors affecting sensitivity and specificity of diagnostic testing: dobutamine stress echocardiography

BACKGROUND

Clinical characteristics of patients, angiographic referral bias, and several technical factors may all affect the reported diagnostic accuracy of tests. The aim of this study was to assess their influence on the diagnostic accuracy of dobutamine stress echocardiography (DSE).

METHODS

The medical literature from 1991 to 2006 was searched for diagnostic studies using DSE and meta-analysis was applied to the 62 studies thus retrieved, including 6881 patients. These studies were analyzed for patient characteristics, angiographic referral bias, and several technical factors.

RESULTS

The sensitivity of DSE was significantly related to the inclusion of patients with prior myocardial infarctions (0.834 vs 0.740, P < .01) and defining the results of DSE as already positive in case of resting wall motion abnormalities rather than obligatory myocardial ischemia (0.786 vs 0.864, P < .01). Specificity tended to be lower when patients with resting wall motion abnormalities were included in a study (0.812 vs 0.877, P < .10). The presence of referral bias adversely affected the specificity of DSE (0.771 vs 0.842, P < .01).

CONCLUSION

This analysis suggests that the reported sensitivity of DSE is likely higher and the specificity lower than expected in routine clinical practice because of the inappropriate inclusion of patients with prior myocardial infarctions, the definition of positive results on DSE, and the negative influence of referral bias. However, in the patient subset that will be sent to coronary angiography, the opposite results can be expected.

Tissue Doppler echocardiographic identification of ischemic etiology in patients with dilated cardiomyopathy

OBJECTIVE

To compare the left ventricular function in patients with ischemic and nonischemic cardiomyopathy using tissue Doppler echocardiography (TDE).

METHODS

We studied 30 patients after myocardial infarction (MI group), 30 patients with dilated cardiomyopathy (DCM group) and 60 healthy volunteers in corresponding control groups. TDE velocities, time intervals of cardiac cycle were measured and dispersion index of TDE parameters was calculated.

RESULTS

Early diastolic velocities were lower in MI group than in DCM group, with similar systolic and late diastolic velocities. The dispersion index of systolic velocities was significantly higher in MI than in DCM group and in controls (respectively 33.1+/-6.0% vs 12.6+/-3.7% vs 15.9+/-5.6%; p < 0.001) and differentiated ischemic from idiopathic dilated cardiomyopathy. In MI group, preejection period was shorter and isovolumic relaxation and diastasis time were longer than in DCM group, with no differences in dispersion index of time intervals between the groups.

CONCLUSIONS

TDE parameters: early diastolic velocity, preejection period, isovolumic relaxation time and the dispersion index of systolic velocities differentiate ischemic and nonischemic etiology of dilated cardiomyopathy.

The diagnostic and prognostic value of tissue Doppler imaging during dobutamine stress echocardiography in end-stage renal disease

OBJECTIVE

To determine whether a quantitative measurement of peak systolic velocity (PSV) during dobutamine stress echocardiography (DSE) detects severe coronary artery disease (CAD) and predicts mortality in patients with end-stage renal disease.

METHODS

One hundred and forty renal transplant candidates had DSE and coronary angiography. DSE analysis was performed using conventional visual wall motion assessment, longitudinal PSV, and combining the two modalities. Failure of PSV to rise by more than 50% predicted an ischemic response. Significant CAD was defined as luminal stenosis greater than 70%.

RESULTS

The number of positive DSE studies according to conventional, PSV, and combined criteria was 41 (30%), 42 (31%), and 46 (34%) respectively. Forty patients (29%) had significant CAD at angiography. The sensitivity, specificity, positive and negative predictive values for conventional DSE analysis were 84, 91, 86, and 90% respectively. The same values for PSV analysis were 86, 92, 86, and 91%, respectively. The same values for the combination of visual and PSV analysis were 88, 94, 87, and 92% respectively. The differences between the three methods were not statistically significant. Sensitivity for single-vessel CAD (P=0.05) and circumflex artery disease (P=0.05) diagnosis was higher with PSV compared with conventional DSE analysis. Failure of PSV to rise by more than 50% during DSE was associated with significantly increased mortality (P=0.001).

CONCLUSION

A quantitative interpretation of DSE, based on the percentage rise of PSV during stress, accurately detects CAD and predicts prognosis in end-stage renal disease.

High thoracic epidural analgesia improves left ventricular function in patients with ischemic heart

BACKGROUND

In patients with ischemic heart disease, high thoracic epidural analgesia (HTEA) has been proposed to improve myocardial function. Tissue Doppler Imaging (TDI) is a tool for quantitative determination of myocardial systolic and diastolic velocities and a derivative of TDI is tissue tracking (TT), which allows quantitative assessment of myocardial systolic longitudinal displacement during systole. The purpose of this study was to evaluate the effect of thoracic epidural analgesia on left ventricular (LV) systolic and diastolic function by means of two-dimensional (2D) echocardiography and TDI in patients with ischemic heart disease.

METHODS

The effect of a high epidural block (at least Th1-Th5) on myocardial function in patients (N=15) with ischemic heart disease was evaluated. Simpson's 2D volumetric method was used to quantify LV volume and ejection fraction. Systolic longitudinal displacement was assessed by the TT score index and the diastolic function was evaluated from changes in early (E'') and atrial (A'') peak velocities during diastole.

RESULTS

After HTEA, 2D measures of left ventricle function improved significantly together with the mean TT score index [from 5.87 +/- 1.53 to 6.86 +/- 1.38 (P<0.0003)], reflecting an increase in LV global systolic function and longitudinal systolic displacement. The E''/A'' ratio increased from 0.75 +/- 0.27 to 1.09 +/- 0.32 (P=0.0026), indicating improved relaxation.

CONCLUSION

A 2D-echocardiography in combination with TDI indicates both improved systolic and diastolic function after HTEA in patients with ischemic heart disease.

Measurements of left ventricular myocardial longitudinal systolic displacement using spectral and colour tissue Doppler: time for a reassessment?

BACKGROUND

Echocardiographic measurements of left ventricular (LV) myocardial displacement may produce different results depending on the choice of employed modality and subjective adjustments during data acquisition and analysis.

METHODS

In this study, left ventricular longitudinal systolic displacement was quantified in 57 patients (31 women and 26 men, 50 +/- 16 years) using colour (colour TD) and spectral tissue Doppler (spectral TD) before and after temporal filtering (30 to 70 milliseconds in 20-millisecond steps) and changed offline gain saturation (0%, 50% and 100%), respectively. The results were compared with those obtained with anatomic M-mode.

RESULTS

Whereas only minor differences occurred between the results of colour TD and anatomic M-mode measurements, spectral TD significantly overestimated the results obtained with both these methods. However, the limits of agreement between the results produced by all three studied methods were not clinically acceptable in any of the cases. The spectral TD displacement values increased along with increasing offline gain saturation whereas the effect of temporal filtering on colour Doppler measurements was insignificant.

CONCLUSION

Measurements of LV myocardial longitudinal displacement employing spectral TD, colour TD or anatomic M-mode produce different results, thus discouraging interchangeable use of these modalities. Whereas the results of spectral TD measurements can be significantly altered by changing offline gain setting, the effect of temporal filtering on colour TD measurements is insignificant, a fact that increases clinical practicality of the latter method.

Sample volume positioning in colour-coded Doppler myocardial imaging: effect of systolic and diastolic tracking

To date, Doppler myocardial imaging (DMI) is no longer an intriguing new research tool only, but is rather on the verge of becoming a routinely used diagnostic method in adult and pediatric cardiology. Clinical studies have proven its diagnostic relevance for global left and right ventricular function. Concerns about reliability and reproducibility of DMI functional analysis, however, rely on lacking standards for the acquisition and analysis of DMI parameters. This study focuses on the effect of sample volume positioning during the cardiac cycle on the absolute myocardial velocities. Our hypothesis was that systolic sample volume placement leads to altered diastolic measurements, and diastolic placement vice versa to altered systolic measurements, when compared with continuous systolic and diastolic tracking. The effect of tracking on intra- and interobserver variability was a second endpoint of the study. Twenty healthy women underwent color-coded Doppler myocardial imaging. Clips of three heart cycles were stored in digital format for off-line analysis, administering sector angles of approximately 30 degrees and a mean frame rate of 280 frames per second. Using the Echopac software (GE, Germany), the sample volume was positioned immediately below the atrioventricular valvar annulus within the basal segments of the right and left ventricular free wall and the interventricular septum. Three conditions were investigated: conventional end-systolic or end-diastolic placement of the Doppler probe, or continuous tracking to the ideal position during systole or diastole. Descriptive statistics, intra and interobserver variabilities and Bland-Altman analyses were performed. Tracking revealed higher values of early diastolic myocardial velocities compared with measurements during systolic sample volume placement only, and higher systolic myocardial velocities, preejection acceleration and late diastolic myocardial velocities using diastolic sample volume placement. Inter and intraobserver reproducibility improved remarkably with the new procedure with the exception of isovolumic acceleration (IVA), which could not be reproduced satisfactorily at all. In summary, tracking is a promising method that helps to improve reproducibility of DMI-derived myocardial velocities. It helps to minimize the effect of changing myocardial velocities during the natural longitudinal cardiac movement, and should be considered as standard method during DMI.

Exercise-induced changes in E/E' ratio in patients with suspected coronary artery disease

OBJECTIVES

Ischemia affects the left ventricular (LV) diastolic function earlier than the systolic function. The ratio of the early diastolic transmitral velocity to the early diastolic tissue velocity (E/E') measured by tissue Doppler echocardiography allows a reliable assessment of the diastolic function. We investigated whether exercise-induced changes in E/E' ratio may help in the detection of coronary artery disease (CAD).

METHODS

The study population consisted of 114 patients undergoing coronary angiography. Patients with impaired LV ejection fraction, earlier myocardial infarction, arterial hypertension greater than stage I, or LV hypertrophy were excluded. Patients underwent a treadmill exercise test combined with an echocardiogram at baseline and within the first minute after exercise.

RESULTS

Coronary angiography showed a stenosis more than 70% in 72 (63%) patients (CAD group), the remaining 42 formed the non-CAD group. The two groups did not differ regarding age, sex, LV dimensions, and function. At baseline, the E/E' lateral and septal ratios and their average did not differ between the two groups. The exercise-induced changes of the E/E' ratios were higher in the CAD group (change of E/E' average: 1.9+/-3.3 vs. -1.1+/-2.3, P<0.001). In the CAD group, 78% showed an exercise-induced increase of E/E' average compared with 24% in the non-CAD group (P<0.001). In multivariate analysis, the association between an increase of E/E' average and the presence of obstructive CAD was independent of traditional risk factors, exercise test result or exercise-induced wall motion abnormalities (odds ratio=8.1, P<0.001).

CONCLUSION

Exercise-induced changes in E/E' ratio may offer significant assistance in the detection of CAD.

New Echocardiographic Techniques for Evaluating Left Ventricular Myocardial Function

Ultrasound imaging of the heart continues to play an important role in diagnosis and management of patients with cardiovascular diseases. Recent advances in ultrasound technology and introduction of newer imaging modalities have enabled improved assessment of left ventricular myocardial function. Tissue Doppler imaging and 2-dimensional speckle tracking allow more objective quantification of myocardial function in the form of tissue velocities, displacement, strain, and strain rate. Similarly, contrast-enhanced echocardiography and 3-dimensional echocardiography have provided a unique insight into left ventricular form and function that was not possible by unenhanced 2-dimensional echocardiography. In this review, the authors discuss the clinical application of these new imaging techniques in the assessment of left ventricular myocardial function.

The resynchronization therapy in narrow QRS study (RethinQ study): Methods and protocol design

BACKGROUND

Numerous trials have demonstrated the effectiveness of cardiac resynchronization therapy (CRT) as an adjunct to medical therapy for the relief of heart failure (HF) symptoms in patients with a wide QRS duration (QRSd). Current guidelines recommend CRT in patients with an EF <35%, medically refractory NYHA Class III-IV HF and QRSd >or=120 ms. Previous studies have demonstrated QRSd as a marker of electrical dyssynchrony fails to predict response to CRT. In addition, studies have demonstrated significant differences in QRSd post CRT between responders and non-responders. Moreover, smaller non-controlled studies demonstrated that HF patients with a narrow QRSd may benefit from CRT. A growing body of evidence suggests that echocardiographic criteria may be a better method to evaluate mechanical dyssynchrony (MD) which may predict those that will benefit from CRT, particularly those with a narrow QRSd. The Resynchronization Therapy In Narrow QRS (RethinQ) study will evaluate mechanical dyssynchrony using echocardiography (both M mode and TDI) as an eligibility requirement for CRT.

METHODS

The RethinQ study is a prospective, multi-center, randomized, double blind controlled clinical study. The objective of the RethinQ study is to evaluate the effectiveness of CRT in patients with approved ICD indication, advanced HF (NYHA Classification III), narrow QRSd (<130 ms) and evidence of MD measured by echocardiography.

CONCLUSION

We hypothesize that patients with narrow QRS <130 ms, advanced HF, and MD as measured by echocardiography will benefit from CRT.

Stress Echocardiography: Abnormal Response of Tissue Doppler?Derived Indices to Dobutamine in the Absence of Obstructive Coronary Artery Disease in Patients with Chronic Renal Failure

BACKGROUND

Abnormal tissue Doppler (TD)-derived indices during dobutamine stress echocardiography (DSE) can predict the presence of coronary artery disease (CAD) in patients with normal renal function. These indices include a reduction in annular systolic velocity (S'), a decrease in early diastolic annular velocity (E'), and prolongation of the time to E'. However, the ability of these indices to detect or exclude CAD in patients with chronic renal failure (CRF) is unclear.

OBJECTIVE

To examine the ability of TD-derived indices to detect or exclude the presence of CAD in patients with CRF.

METHODS

We evaluated a total of 30 patients (13 males, mean age 57 +/- 15 years) using both DSE and coronary angiography. This cohort consisted of 12 control patients with normal renal function (mean creatinine 0.5 mg/dL) and 18 patient with CRF (mean creatinine 2.5 mg/dL). At each stage of the DSE, left ventricular (LV) diastolic function was assessed using conventional (peak early (E) and late (A) transmitral, E/A ratio, E-wave deceleration time (DT), and isovolumic relaxation time (IVRT)) and TD-derived indices (lateral annular systolic (S'), early diastolic (E'), and late atrial velocities (A'), time to E' and E/E').

RESULTS

All 30 patients had a normal DSE based on systolic regional function and a normal coronary angiogram. There was no difference in E, A, E/A, DT or IVRT between the two groups at each stage. Despite normal coronaries, patients with CRF demonstrated lower S' and E' velocities at peak stress compared to the control patients (8.0 +/- 2.2 cm/sec vs 15.1 +/- 2.6, P < 0.05 and 6.7 +/- 1.6 cm/sec vs 13.3 +/- 3.1, P < 0.05, respectively). During DSE, the time to E' at peak stress in CRF patients was also prolonged compared to control (400 +/- 44 ms vs 329 +/- 51, P < 0.05). Patients with CRF also had increased filling pressures (as estimated by E/E') as compared to controls at peak stress (14.7 +/- 5.2 vs 7.4 +/- 1.5, P < 0.05, respectively).

CONCLUSION

In patients with CRF, a reduction in TD derived indices does not predict the presence of obstructive CAD.

Velocity Tracking–A Novel Method for Quantitative Analysis of Longitudinal Myocardial Function

Doppler tissue imaging is a method for quantitative analysis of longitudinal myocardial velocity. Commercially available ultrasound systems can only present velocity information using a color Doppler-based overlapping continuous color scale. The analysis is time-consuming and does not allow for simultaneous analysis in different projections. We have developed a new method, velocity tracking, using a stepwise color coding of the regional longitudinal myocardial velocity. The velocity data from 3 apical projections are presented as static and dynamic bull's-eye plots to give a 3-dimensional understanding of the function of the left ventricle. The static bull's-eye plot can display peak systolic velocity, late diastolic tissue velocity, or the sum of peak systolic velocity and early diastolic tissue velocity. Conversely, the dynamic bull's-eye plot displays how the myocardial velocities change over one heart cycle. Velocity tracking allows for a fast, simple, and intuitive visual analysis of the regional longitudinal contraction pattern of the left ventricle with a great potential to identify characteristic pathologic patterns.

Propofol reduces tissue-Doppler markers of left ventricle function: a transthoracic echocardiographic study

BACKGROUND

Propofol is thought to minimally depress myocardial function, but mainly to reduce blood pressure by vasodilation. Transthoracic tissue-Doppler echocardiography (TDE) is a novel, validated method of quantifying myocardial function. It provides new insight into myocardial function by measuring myocardial motion. We examined the effects of propofol upon myocardial function by measuring changes in left ventricle function by TDE.

METHODS

We assessed change in myocardial function in propofol anaesthetized ASA I patients tissue tracking displacement (TTD) before anaesthesia onset and repeated measurements after a single propofol bolus dose. Tissue tracking score (TTS), a marker of ejection fraction, was also used (n = 10).

RESULTS

Propofol 1.5-2 mg kg(-1) significantly attenuated PSV from 5.64 (1.17) to 4.66 (0.55) cm s(-1) (P < 0.0001) and TTD from 10.2 (2.1) to 8.5 (1.4) mm (P = 0.0091), whereas TTP was unchanged [all data: mean (SD)]. TTS declined from 7.2 (1.3) to 6.1 (0.6) mm (P < 0.01). Non-invasive mean blood pressure declined 17% (P < 0.0001).

CONCLUSIONS

The results indicate that myocardial contractile function is compromised concomitantly with reduced cyclic displacement after propofol dosing. Blood pressure declined accordingly. From these results, it is impossible to ascertain whether this was secondary to reduced cardiac filling or a consequence of a direct negative inotropic action of propofol, but it represents a left-shift of the Starling curve. The novel TDE yields new information on myocardial velocities and motion.

Tissue Doppler and innovative myocardial-deformation imaging techniques for assessment of myocardial viability

PURPOSE OF REVIEW

Visual analysis of stress echocardiography allows evaluation of myocardial viability in acutely and chronically impaired left-ventricular function. Tissue Doppler and derived echocardiographic imaging techniques provide a tool for quantification of regional left-ventricular function which overcomes the limitations of subjective, experience-dependent reading of stress echocardiography.

RECENT FINDINGS

Regional systolic and diastolic myocardial velocities as well as the derived myocardial-deformation parameters strain and strain rate are impaired in patients with left-ventricular dysfunction. Increase of myocardial velocities, strain and strain rate during stress stimulation are indicators of functional reserve in viable segments, while failure to increase indicates nonviability. Previous studies with very precise determination of regional myocardial deformation have shown that even analysis of resting function without evaluation of the functional reserve during stimulation allows assessment of myocardial viability. New two-dimensional echocardiography-based tissue-tracking techniques yield an angle-independent imaging modality that is likely to further improve the clinical applicability of echocardiographic imaging techniques to define regional myocardial viability.

SUMMARY

This review attempts to define the role of tissue Doppler and new innovative myocardial-deformation imaging techniques for identification of myocardial viability in patients with impaired left-ventricular function.

Potential clinical perspectives of Doppler myocardial imaging and strain rate imaging during stress echocardiography

Stress echocardiography has become a common non-invasive test in patients with chest pain and known or suspected coronary artery disease, but, as with exercise electrocardiography, it shows several major limitations. Analysis of gray-scale images based on subjective visual interpretation of wall motion and thickening has considerable variability even among experts. Doppler myocardial imaging and strain rate imaging echocardiography provides additional information in comparison with conventional echocardiography. These techniques provide quantification of regional wall motion at rest and during stress. Quantification of both systolic and diastolic myocardial function by either Doppler myocardial imaging or strain rate imaging mapping during dobutamine stress test has been shown to be a feasible, accurate, non-invasive tool that should be considered to be a sensitive alternative to the present echocardiographic and scintigraphic imaging techniques for stress tests. Time consuming off-line analysis of color images is required in the present state of technology. However, these non-invasive techniques are rapidly evolving and expanding. Further refinements in signal processing and quantitative analysis are likely in the near future.

Tissue velocity imaging during dobutamine stimulation for assessment of myocardial viability: Segmental analysis in patients after myocardial infarction

BACKGROUND

Dobutamine stress echocardiography (DSE) is an established method for the detection of viable myocardium, but evaluation of this method is subjective. Tissue velocity Imaging (TVI) allows quantitative analysis of regional myocardial wall motion by assessment of systolic myocardial velocities. The aim of this study was to evaluate the diagnostic value of DSE and TVI for detection of viable myocardium.

METHODS

In 56 patients (58+/-12 years) with previous myocardial infarction (130+/-42 days, mean ejection fraction 42+/-15%) low-dose DSE was combined with analysis of peak systolic myocardial velocities (Vpeak) by TVI for assessment of myocardial viability. As reference served a follow-up echocardiography after successful revascularization (mean 91+/-3 days).

RESULTS

Of a total of 896 segments 200 showed abnormal wall motion (31 mildly hypokinetic, 50 severely hypokinetic, 115 akinetic, 4 dyskinetic). In 125 of these 200 segments regional improvement of regional wall motion was observed (62.5% viable). An increase of Vpeak>1 cm/s during dobutamine stimulation allowed the identification of viable myocardium with a sensitivity of 82% and a specificity 82% (DSE: 77% and 80%). By receiver operating characteristic (ROC) curve analysis, a cut-off value of 1.0 cm/s was the best parameter to differ viable from nonviable myocardium (area under the curve 0.85; p<0.01; 95% CI 0.79 to 0.90). Improvement of global ejection fraction after revascularization (47+/-13%, p=0.11) corresponded with three TVI viable segments with a sensitivity of 92% and a specificity of 89% (p=0.012).

CONCLUSIONS

TVI allows the identification of viable myocardium during dobutamine stimulation and enables a quantitative interpretation of DSE.

Regional Response of Myocardial Acceleration During Isovolumic Contraction During Dobutamine Stress Echocardiography: A Color Tissue Doppler Study and Comparison with Angiocardiographic Findings

BACKGROUND

Color tissue Doppler imaging permits noninvasive quantitation of regional wall motion. In experimental studies, a new marker, the slope of the isovolumic contraction wave, isovolumic acceleration (IVA) was more insensitive to ventricular loading conditions than myocardial velocities. This study compared the regional response IVA to dobutamine stress echocardiography to angiographic findings.

METHODS

The Myocardial Doppler in Stress Echocardiography (MYDISE) study prospectively recruited 149 consecutive patients with chest pain for dobutamine stress tissue Doppler echocardiography prior to coronary angiography. This color tissue Doppler database was analyzed for IVA in 1,192 basal and mid segments at rest and again at peak stress. Angiographic findings were compared to IVA and peak systolic velocities (PSV) in corresponding cardiac segments. The diagnostic accuracy of IVA to predict coronary artery stenosis was determined using cut-off values for three representative segments and with the MYDISE diagnostic model including eight segments.

RESULTS

Regional IVA increased in a dose-dependent manner during dobutamine infusion. The response was blunted in the supply territory of stenosed coronary artery branches. IVA performed slightly better than PSV as single marker for coronary artery stenosis. A diagnostic model incorporating IVA and PSV was 85-95% accurate (area under receiver operating characterstic curves).

CONCLUSIONS

Regional changes of isovolumic acceleration during dobutamine stress echocardiography reflect regional wall motion and can be used to predict coronary artery stenosis with similar accuracy as a model based on systolic myocardial velocities. As a single marker, IVA performed better than myocardial velocities.

Stress echocardiography for the diagnosis of coronary artery disease: progress towards quantification

PURPOSE OF REVIEW

This review highlights recent progress in the quantitative approach to the interpretation of stress echocardiograms. Recent literature regarding the application of tissue Doppler and strain rate imaging for the diagnosis of coronary artery disease is summarized.

RECENT FINDINGS

The high temporal and spatial resolution of tissue Doppler and strain rate imaging permit recognition of regional myocardial dysfunction. These techniques have been performed during low- and high-dose dobutamine stress echocardiography and have been applied to exercise echocardiography. During stress, the peak systolic velocity and early diastolic velocity increased to a greater degree in normal segments compared to ischemic segments. With tissue Doppler imaging, viable segments show increases in systolic velocities in contrast to infarcted segments. Presently, the feasibility of strain rate imaging is slightly less than that of conventional wall motion assessment. However, in preliminary studies, tissue Doppler parameters and especially strain rate parameters appear to offer advantages in accuracy compared to conventional wall motion assessment.

SUMMARY

Tissue Doppler and strain rate imaging offer great promise for the accurate, reproducible quantification of regional myocardial function. Further studies are indicated to prove their accuracy, efficiency, and superiority over existing methods.

Usefulness of angle corrected tissue Doppler to assess segmental left ventricular function during dobutamine stress echocardiography in patients with and without coronary artery disease

The application of angle correction to tissue Doppler (TD) during dobutamine stress echocardiography (DSE) extends the application of TD to all left ventricular segments, improves the differentiation of abnormal from normal segmental responses to stress, and has promise to improve its clinical utility for objectively evaluating wall motion during DSE.