Detection of coronary artery disease with a continuous infusion of definity ultrasound contrast during adenosine stress real time perfusion echocardiography.

BACKGROUND: Myocardial perfusion imaging during adenosine stress is an accurate method of detecting physiologically relevant coronary artery disease. METHODS: Real time perfusion echocardiography (RTPE) was compared to nuclear scintigraphy (rest Thallium, stress Sestamibi) in 40 patients with intermediate to high pretest probability. RTPE was performed with a continuous infusion of intravenous microbubbles (Definity; Bristol Myers Squibb) and intermittent high mechanical index impulses, with visual examination of both the replenishment rate and plateau intensity of contrast. RESULTS: Of the 119 coronary artery territories compared, SPECT and RTPE were in agreement in 105 (88% agreement; kappa 0.67). In patients who went on to quantitative coronary arteriography (QCA), there were three who had normal appearing radionuclide SPECT during adenosine, but subendocardial perfusion defects with RTPE. In all three cases, QCA confirmed the presence of a >50% diameter stenosis in the abnormal territory. CONCLUSIONS: We conclude from this study that adenosine stress imaging with RTPE is an accurate method of detecting coronary artery disease. The higher resolution of RTPE may identify subendocardial defects that would otherwise have gone undetected with radionuclide imaging.

Comparison of low-mechanical index pulse sequence schemes for detecting myocardial perfusion abnormalities during vasodilator stress echocardiography.

Myocardial contrast echocardiography has the potential to accurately detect functionally significant coronary artery disease during pharmacologic stress testing. Different low-mechanical index modalities, including triggering replenishment imaging (TRI) and real-time imaging (RTI), are currently used to identify myocardial perfusion defects. We compared the ability of TRI with that of RTI for detecting and localizing perfusion abnormalities. Thirty-six patients (62 +/- 14 years old, 15 men) underwent single-photon emission computed tomography (SPECT) with technetium-99m sestamibi and myocardial contrast echocardiography at baseline and after infusion of 0.56 mg/kg of dipyridamole. Sixteen of these patients also underwent quantitative angiography. Contrast-enhanced images were obtained in 4-, 3-, and 2-chamber views after intravenous bolus injections of lipid-encapsulated microbubbles (0.1 ml of Definity). A myocardial perfusion defect was defined by myocardial contrast echocardiography as a delay of >2 seconds in contrast replenishment after high-mechanical index flash impulse. The myocardial segments were divided into 3 major coronary territories. There was agreement in detecting perfusion defects between SPECT and TRI in 26 patients (72%, kappa = 0.46) and between SPECT and RTI in 27 patients (75%, kappa = 0.50). Agreements between myocardial contrast echocardiography and SPECT for localizing coronary territories with perfusion defects were 81% for TRI (kappa = 0.43) and 85% for RTI (kappa = 0.61). Accuracy of RTI for detecting >50% diameter stenoses by quantitative angiography was 79%, that of TRI was 71%, and that of SPECT was 65%. These data indicate that the different low-mechanical index imaging schemes are equivalent to radionuclide SPECT in accurately detecting diseased coronary artery territories during vasodilator stress.

Assessment of papillary muscle function using myocardial velocity gradient derived from tissue Doppler echocardiography.

Papillary muscle (PM) function is vital to mitral valve competence. However, quantitative assessment of the function is difficult due to the complexity of the mitral apparatus. We hypothesized that myocardial velocity gradient (MVG) could be applied to assess PM function. We studied MVG-PM in 123 patients with left ventricular dysfunction (ejection fraction <40%) and 123 normal subjects throughout a systolic phase. MVG-PM in normal subjects was significantly higher than in patients with left ventricular dysfunction (3.6/s vs 1.4/s, p <0.001). MVG-PM reached its peak at early systole and correlated well with PM thickening (r = 0.89). MVG-PM in patients with left ventricular dysfunction correlated with the severity of apical tenting of the mitral valve (y = 0.8x - 0.07, r = 0.72). Patients with lower MVG-PM tended to have less severe mitral regurgitation (y = 0.03x + 0.3, r = 0.83). PM contractility can be quantitatively assessed by calculating the MVG derived from tissue Doppler imaging. PM dysfunction, indicated by lower MVG-PM, decreased mitral leaflet tethering, thus paradoxically decreasing mitral regurgitation severity. MVG is a useful tool in determining the role of PM in functional mitral regurgitation.

Peak atrial systolic mitral annular velocity by Doppler tissue reliably predicts left atrial systolic function.

Left atrial (LA) function assessment is important in clinical practice. We studied peak atrial tissue velocity (A') and quantitative echocardiographic methods of LA function in 120 patients (54 men; mean age 58 years) who were in sinus rhythm. Patients were divided into 2 groups: patients with increased left ventricular mass; and healthy subjects. There was no difference for peak late filling velocity (A) and A velocity time integral between groups. Patients with increased left ventricular mass had higher A', LA ejection fraction, LA ejection force, and LA kinetic energy. A' correlated well with LA ejection fraction (r = 0.8), LA ejection force (r = 0.87), and LA kinetic energy (r = 0.87). A' could also assess LA function for patients with depressed left ventricular function. Subsequently, we assessed A' in 16 patients with restrictive physiology and found that A' also correlated well with quantitative methods of LA function. A' correlates well with quantitative methods of LA function, and could be readily applied for quantifying LA contribution to diastolic performance in clinical practice.