The usefulness of contrast during exercise echocardiography for the assessment of systolic pulmonary pressure.

BACKGROUND: The systolic pulmonary artery pressure (PAPs) can be accurately estimated, non-invasively, using continuous-wave Doppler (CWD) ultrasound measurement of the peak velocity of a tricuspid regurgitant (TR) jet. However, it is often difficult to obtain adequate tricuspid regurgitation signals for measurement of PAPs, what could lead to its underestimation. Therefore, utilization of air-blood-saline contrast has been implemented for the improvement of Doppler signal in several clinical contexts. It is now recommended in the evaluation of patients with pulmonary hypertension. Physical activity is severely restricted in patients with PAH, being exertional dypnea the most typical symptom. Exercise stress echo-Doppler imaging allows assessment of the response to exercise. It is an excellent screening test for patients with suspected PAH. Our purpose was to evaluate the value and accuracy of agitated saline with blood contrast echocardiography, in the improvement of the Doppler signal, to quantify PAPs during treadmill exercise-echocardiography. PURPOSE: To evaluate the value of contrast echocardiography, using agitated saline with blood, in the improvement of the Doppler signal used to quantify the pulmonary artery systolic pressure during exercise. METHODS: From a total of 41 patients (pts), we studied 38 pts (93%), 35 women, aged 54 +/- 12 years-old. 27 with the diagnosis of systemic sclerosis, 10 with history of pulmonary embolism and one patient with a suspected idiopathic PAH, who were referred to the Unity of Heart Failure and Pulmonary Hypertension for screening of PAH. According to the Unity protocol, a transthoracic echocardiogram was made, in left decubitus (LD), with evaluation of right ventricle-right atria gradient (RV/RAg). A peripheral venous access was obtained, with a 3-way stopcock and the patients were placed in orthostatism (O), with a new evaluation of RV/RAg. Exercise echocardiography (EE) was begun, with evaluation of RV/RAg at peak exercise (P) and afterwards agitated saline (8 cc with 1 cc of air and 1 cc of blood) was injected, followed by a new evaluation of RV/RAg (PC) and then the interruption of the EE. Pulmonary Hypertension was diagnosed when RV/RAg at the end of the exercise was superior to 40 mmHg. RESULTS: The quality of Doppler signal was deteriorated in 5 pts, maintained in 6 pts and improved in 26 pts, with the use of contrast. In one patient, an interventricular septal defect was diagnosed. In 6 pts, a Doppler signal was only obtained with the use of contrast. In 15 pts, a RV/RAg superior to 40 mmHg was only obtained with the use of contrast. Of these, 9 have already been submitted to right heart cathetherism, that confirmed the diagnosis of pulmonary hypertension in 5 of them (56%). RV/RAg (P) was 44 +/- 11 mmHg and RV/RAg (PC) was 54 +/- 11 mmHg, p < 0,001. CONCLUSION: 1. The method is applicable in a large number of patients. 2. RV/RA gradients obtained at peak exercise are higher with the use of contrast, and the clinical meaning of this difference should be evaluated in a larger number of pts submitted to right heart cathetherism. The high number of false positives should lead to a higher diagnostic threshold. 3. This method seems to have relevant clinical value in the diagnosis of pulmonary arterial hypertension.

[Cardiac imaging in suspected coronary artery disease]. / Kardiale Bildgebung bei Verdacht auf eine koronare Herzkrankheit.

Within the scope of this review, non-invasive imaging modalities applicable for further work-up of suspected coronary artery disease (CAD) are discussed with regard to methodology, diagnostic accuracy and prognostic value. All of these imaging modalities can be employed in patients with an intermediate pretest probability of disease, if ECG stress testing is either not reasonable, not possible due to physical limitations or if the result is inconclusive. Stress echocardiography is a cost-effective and an easily practicable method based on the indirect detection of myocardial ischemia by visually assessing provoked wall motion abnormalities. Therefore, its diagnostic value is mainly determined by individual expertise. In case of myocardial scintigraphy, reduced myocardial perfusion causes signal intensity differences in SPECT images following physical or pharmacological stress which are reversible at rest. Myocardial scintigraphy is characterised by a high negative predictive value at the expense of a lower specificity due to false positive results based on methodological limitations. Cardiovascular magnetic resonance imaging (CMR) offers a comprehensive cardiac study in a single procedure. Apart from detecting myocardial ischemia by dobutamine-stress-CMR or adenosine-perfusion-CMR, it enables the precise detection of even small areas of myocardial infarction on contrast-enhanced images. In spite of fascinating high-resolution coronary images, multi-detector computed tomography (MDCT) has hardly been included in current guidelines due to the unavoidable risks of radiation and contrast medium exposure and the current uncertainty in defining appropriate clinical indications. However, quantification of coronary calcium is easily performed and may be useful for prognostic assessment in patients with intermediate risk profile.

Safety of stress echocardiography (from the International Stress Echo Complication Registry).

The safety of any diagnostic test is a major issue in deciding its practicability and cost-effectiveness. The aim of this study was to evaluate the safety of various stress echocardiographic modalities in the "real world." From February 1998 to January 2004, a simple written questionnaire was distributed to echocardiography laboratories across the world known to perform stress echocardiography. The following categories of major complications (known to occur during stress testing) were indicated: sustained ventricular tachycardia (> 30 beats/min), ventricular fibrillation, myocardial infarction, third-degree atrioventricular block, severe hypotension requiring therapy, cardiac asystole, cardiac rupture, stroke, and death. Three hundred centers were polled, from which 71 co-investigators responded and reported on 85,997 patient examinations. Exercise was used in 26,295 cases, dobutamine in 35,103, and dipyridamole in 24,599 cases. Life-threatening events occurred in 86 cases: during exercise in 4 patients (event rate 1 in 6,574), during dobutamine infusion (small dose for viability and/or large dose for ischemia) in 63 patients (event rate 1 in 557), and during dipyridamole stress testing in 19 patients (event rate 1 in 1,294). Of the 86 patients with complications, 5 died during dobutamine stress testing (ventricular fibrillation, n = 2; cardiac rupture, n = 3) and 1 after dipyridamole testing (cardiogenic shock). In conclusion, stress echocardiography is a safe method in the real world, but serious complications may occur. Exercise seems safer than pharmacologic stress and dipyridamole safer than dobutamine, possibly because of preselection criteria.

Comparison of real-time tri-plane and conventional 2D dobutamine stress echocardiography for the assessment of coronary artery disease.

AIMS: Although dobutamine stress echocardiography (DSE) is an accepted tool for the diagnosis of coronary artery disease (CAD), it requires subsequent image acquisitions of the left ventricle (LV) in order to visualize all segments. This makes the procedure relatively time-consuming and might limit its accuracy. With the introduction of matrix array transducers, the real-time simultaneous acquisition of all LV segments has become possible using multi-plane imaging. The purpose of this study was: (i) to test the feasibility and efficiency of real-time tri-plane (RT3P) imaging during DSE, (ii) to compare the accuracy of RT3P DSE in detecting CAD using coronary angiography as the reference method. METHODS AND RESULTS: Thirty-six patients suspected of CAD were prospectively enrolled. Both conventional two-dimensional (2D) and RT3P imaging were performed during a DSE protocol. Coronary angiography was performed within 24 h. Ultrasound data were acquired at each stage of the DSE. The total effective acquisition time for RT3P imaging was significantly shorter (55+/-29 vs. 137+/-63 s, P<0.001). Data yield was similar for both methods (2D: 98% vs. 3D: 97%). Overall sensitivity (93%), specificity (75%), and accuracy (89%) were identical between both methods. On a segmental level, the sensitivity, specificity, and accuracy of the RT3P and the 2D DSE were similar. CONCLUSION: RT3P imaging fastens the DSE protocol without compromising the accuracy for the diagnosis of CAD. This could facilitate a more wide-spread use of DSE and therefore contributes positively to its routine clinical acceptance.

Incremental value of strain rate analysis as an adjunct to wall-motion scoring for assessment of myocardial viability by dobutamine echocardiography: a follow-up study after revascularization.

BACKGROUND: Assessment of myocardial viability based on wall-motion scoring (WMS) during dobutamine echocardiography (DbE) is difficult and subjective. Strain-rate imaging (SRI) is quantitative, but its incremental value over WMS for prediction of functional recovery after revascularization is unclear. METHODS AND RESULTS: DbE and SRI were performed in 55 stable patients (mean age, 64+/-10 years; mean ejection fraction, 36+/-8%) with previous myocardial infarction. Viability was predicted by WMS if function augmented during low-dose DbE. SR, end-systolic strain (ESS), postsystolic strain (PSS), and timing parameters were analyzed at rest and with low-dose DbE in abnormal segments. Regional and global functional recovery was defined by side-by-side comparison of echocardiographic images before and 9 months after revascularization. Of 369 segments with abnormal resting function, 146 showed regional recovery. Compared with segments showing functional recovery, those that failed to recover had lower low-dose DbE SR, SR increment (DeltaSR), ESS, and ESS increment (DeltaESS) (each P<0.005). After optimal cutoffs for the strain parameters were defined, the sensitivity of low-dose DbE SR (78%, P=0.3), DeltaSR (80%, P=0.1), ESS (75%, P=0.6), and DeltaESS (74%, P=0.8) was better though not significantly different from WMS (73%). The specificity of WMS (77%) was similar to the SRI parameters. Combination of WMS and SRI parameters augmented the sensitivity for prediction of functional recovery above WMS alone (82% versus 73%, P=0.015; area under the curve=0.88 versus 0.73, P<0.001), although specificities were comparable (80% versus 77%, P=0.2). CONCLUSIONS: The measurement of low-dose DbE SR and DeltaSR is feasible, and their combination with WMS assessment improves the sensitivity of viability assessment with DbE.

Right vs. left ventricular contractile reserve in one-year prognosis of patients with idiopathic dilated cardiomyopathy: assessment by dobutamine stress echocardiography.

AIM: To determine prognostic implications of the assessment of right (RV) vs. left ventricular (LV) contractile reserve with dobutamine echocardiography in patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Forty-eight consecutive patients (41 male, NYHA class III/IV 13 patients, LV ejection fraction 19+/-8%) were subjected to dobutamine stress echocardiography in incremental stages lasting 5 min each. Contractile reserve was defined as the difference between the values of LV ejection fraction and RV fractional area change obtained at peak dobutamine dose and the baseline values. Patients were followed for one year after enrollment for combined end-point of cardiac death, partial left ventriculectomy and hospitalization for congestive heart failure. During the follow-up 15/48 patients reached combined end-point. Patients who reached end-point had lower RV and LV contractile reserves (14+/-5 vs. 8+/-6%, p=0.0014, and 9+/-5 vs. 3+/-2%, p<0.001, respectively). Kaplan-Meier curves demonstrated that both LV and RV contractile reserves can identify patients with dismal prognosis (log rank=17.02 and log rank=14.66, respectively, p<0.001 for both). Multivariate analysis identified dobutamine induced change in LV functional reserve as the only independent predictor of combined end-point (beta=-0.63, p=0.0035). CONCLUSION: Both RV and LV contractile reserves can be used for prognostic stratification in patients with idiopathic dilated cardiomyopathy. It appears that dobutamine induced change in LV functional reserve may better identify patients with dismal prognosis.

Implementing contrast echocardiography in the laboratory.

Contrast echocardiography is an important and a significant addition to a modern echocardiography laboratory. Its successful implementation is dependent on a team approach between sonographers, nurses, and physicians. A practical plan is one that includes a proper understanding of indications, logistical matters, technical and performance standards, and reimbursement issues.

Clinical benefits of using second generation ultrasound contrast agents in stress echocardiography.

Stress echocardiography is an established and widely used method for the noninvasive detection of myocardial ischemia. However, despite introduction of new echocardiographic technologies, such as harmonic imaging, unsatisfactory image quality limits an accurate interpretation of left ventricular (LV) wall thickening and motion in up to 30% of patients during stress echocardiography. Development and availability of second generation transpulmonary contrast agents, which opacify the LV chamber and have the capability of enhancing endocardial border definition, facilitate high-quality imaging of LV structures even in technically difficult patients. Application of a contrast agent is not associated with significant extra cost of time and manipulations because bolus injections are sufficient in most instances and harmonic imaging capabilities as well as contrast specific presets are implemented and, thus, readily available in most modern ultrasound systems. Numerous studies have demonstrated that contrast echocardiography substantially improves LV cavity visualization at rest as well as at peak stress and, therefore, increases reader confidence and decreases interobserver variability. Moreover, enhanced learning curves for interpreting stress echocardiograms have been reported in novice readers. It has been reported that compared with native stress echocardiography the use of contrast results in identification of more true positive as well as true negative results and helps to avoid unnecessary invasive procedures in a considerable number of patients. Contrast stress echocardiography may, therefore, also prove cost effective in the future. Further refinements of contrast agent properties and new developments in imaging technology will likely continue to extend the spectrum of diagnostic cardiac imaging techniques and further enhance noninvasive assessment of the complex pathophysiology of coronary artery disease.