P.Anthony N. Chandraratna

Determination of cardiac output by transcutaneous continuous-wave ultrasonic Doppler computer.

To evaluate the accuracy of a new, portable, continuous-wave Doppler computer (Ultracom) in measuring cardiac output (CO), simultaneous thermodilution CO and Doppler CO were measured in triplicate in 39 selected patients. Technically adequate Doppler CO studies were obtained in 36 patients. Aortic root diameter was measured by echocardiography and the cross-sectional area was calculated. A continuous-wave Doppler transducer was placed in the suprasternal notch, directed toward the ascending aorta and angled until the maximal velocity signal was achieved. The systolic velocity integral was computed using fast Fourier transform technique. The Doppler CO was computed from the equation: CO = aortic cross-sectional area X systolic velocity integral X heart rate. Interobserver and intraobserver variability studies were also performed. CO measured by thermodilution ranged from 1.86 to 10.1 liters/min (mean 5.26 +/- 1.91 [+/- standard deviation]) and CO by the Doppler method ranged from 1.63 to 10.9 liters/min (mean 5.32 +/- 1.83). The correlation coefficient was 0.97 (p less than 0.001) and standard error of the estimate was 0.42. The regression equation showed that Doppler CO = 0.408 + 0.93 X thermodilution CO. The correlation in 29 volunteers for interobserver variability was 0.98 (p less than 0.001) and in 18 volunteers for intraobserver variability was 0.97 (p less than 0.001). Thus, CO can be determined accurately in many patients using this Doppler technique by trained and experienced persons; intra- and interobserver variability is small.

Mitral valve aneurysm: Clinical features, echocardiographic-pathologic correlations

Aneurysm of the mitral valve occurs most commonly in association with infective endocarditis of the aortic valve. The probable mechanism of its formation is destruction of the aortic valve which results in a regurgitant jet that strikes the anterior leaflet of the mitral valve, creating a secondary site of infection leading to the development of an aneurysm. Perforation of these aneurysms may occur, resulting in mitral regurgitation and pulmonary edema from a ventricle already volume overloaded from aortic regurgitation. This report describes the clinical and echocardiographic-pathologic findings in five patients with pathologically proven aneurysm of the mitral valve. There are no clinical features that appear specific for this abnormality. The two-dimensional echocardiographic feature that is helpful in the diagnosis is a bulge of the mitral valve leaflet toward the left atrium that persists throughout the cardiac cycle. Preoperative diagnosis is important because a mitral valve aneurysm may produce serious complications and is frequently overlooked during surgery. Repair of the aneurysm may be feasible; otherwise, valve replacement becomes necessary. Careful two-dimensional echocardiographic examination should be done in patients with left-sided infective endocarditis to detect an aneurysm of the mitral valve.

Comparison of Doppler echocardiographic and hemodynamic indexes of left ventricular diastolic properties in coronary artery disease

Transmitral flow velocity was measured by Doppler echocardiography in 15 patients with coronary artery disease simultaneously with high-fidelity recording of left ventricular pressure. Doppler echocardiographic recordings were also performed in 14 age- and heart rate-matched normal subjects. Statistically significant differences (p less than 0.05) in acceleration half-time (55.3 +/- 8.2 vs 70.4 +/- 14.9 ms), deceleration half-time (83.1 +/- 17.9 vs 109.5 +/- 18.1 ms), deceleration rate (4.9 +/- 0.9 vs 3.1 +/- 0.9 m/s2), peak velocity of early diastolic left ventricular inflow (E wave) (0.78 +/- 0.13 vs 0.61 +/- 0.13 m/s) and A/E ratio (0.74 +/- 0.20 vs 0.98 +/- 0.31) between normal subjects and patients were noted. There was no significant difference in peak velocity of atrial systolic flow (A wave) between normal subjects and patients. Correlation between transmitral flow indexes and hemodynamic indexes of left ventricular diastolic properties were poor, with r values ranging from 0.02 to 0.65. Significant correlations between deceleration rate versus maximal isovolumic left ventricular pressure decrease (maximum -dP/dt) and A wave versus maximum -dP/dt (p less than 0.05) were found (0.53 and 0.65, respectively). Deceleration rate was the most sensitive index of isovolumic relaxation assessed by hemodynamic methods, whereas the A/E ratio was a poor indicator of hemodynamic measurements of isovolumic relaxation. An abnormal deceleration rate had 100% specificity for detecting abnormal maximum -dP/dt, while abnormal acceleration half-time, deceleration half-time and A/E ratio had 80% specificity for detecting abnormal time constant. The deceleration rate, acceleration half-time, deceleration half-time and A/E ratio had a predictive value of 60 to 100% for the detection of abnormal maximum -dP/dt and time constant.

Accuracy of evaluation of the presence and severity of aortic and mitral regurgitation by contrast 2-dimensional echocardiography

Abstract Contrast 2-dimensional (2-D) echocardiography was performed during cardiac catheterization to compare the technique with cineangiography in evaluating the presence and severity of aortic (AR) and mitral regurgitation (MR). A physiologic solution was injected through the intracardiac catheter while echocardiograms were recorded in multiple views. AR was evaluated in 35 patients; an adequate 2-D echocardiogram was obtained in every patient. Cineangiography was adequate for diagnosis in every patient, but in 3 patients AR could not be graded because of technical problems. Twenty-six patients had AR by 2-D echocardiography and cineangiography and 9 did not have AR by either 2-D echocardiography or cineangiography. Thus, the specificity, sensitivity and predictive accuracy was 100% for detection of AR by 2-D echocardiography. Severity of AR was graded (0 to 4+) by visual inspection in both methods, and severity by both methods correlated with r = 0.998. MR was evaluated in 59 patients. Because of technical problems, MR could not be evaluated by cineangiography in 15, by 2-D echocardiography in 5, or by either method in 2. In 2 patients, although it could be detected, the severity of MR could not be graded by cineangiography. Of 37 patients with satisfactory studies, MR was detected by 2-D echocardiography and by cineangiography in 16; MR was detected only by 2-D echocardiography in 2, only by cineangiography in 3 and by neither method in 16. The sensitivity of 2-D echocardiography for detection of MR was 84%, specificity 89%, positive predictive accuracy 89%, and negative predictive accuracy 84% compared with cineangiography. The severity of MR by both methods correlated with r = 0.998. Contrast 2-D echocardiography for the evaluation of the presence and severity of AR and MR is both sensitive and specific, particularly for AR. In the cardiac catheterization laboratory, this method should be of greatest value when use of cineangiography is limited by the dose of contrast medium, radiation or by technical problems, particularly those encountered with left ventricular angiography.

Accuracy of nondirected and directed M-mode echocardiography as an estimate of left atrial size

M-mode echocardiography has customarily been used to assess left atrial (LA) size noninvasively; it is thought that this provided a more accurate estimate than chest x-ray. Normal subjects have been studied systematically and normal ranges of M-mode measurements defined with good reproducibility.1–3 However, a good correlation between M-mode LA dimension and LA volume has not been consistently demonstrated. Schabelman et al4 compared M-mode LA dimension with biplane angiographic volume and found a poor correlation (r = 0.50, y = 1.5x – 10.9). The best correlation of these 2 parameters they could attain was by fitting the M-mode dimension to a power function (y = 3.7x1.8) and then the correlation coefficient was only 0.69. Two-dimensional (D) echocardiography has also been used to assist in the measurement of LA dimension,5 and there has been some evidence suggesting that the use of 2-D echocardiographic direction of the M-mode beam can improve the accuracy of unidirectional echocardiographic measurement in predicting LA size.6 We report an evaluation of the relation of M-mode echocardiographic LA dimension, both independently and with 2-D echocardiographic direction, to LA volume.

Renal Vasodilatory Effect of Endothelial Stimulation in Patients With Chronic Congestive Heart Failure

OBJECTIVES This study sought to examine the vasodilatory response of the renal circulation to endothelial stimulation in patients with chronic heart failure. BACKGROUND Renal blood flow is often reduced in patients with chronic congestive heart failure and may lead to deterioration of renal function. Stimulation of renal endothelium has been shown to cause renal vasodilation in animals and in isolated human renal artery. The vasoregulatory role of the renal endothelium in patients with heart failure has not been evaluated. METHODS Renal vasodilatory effect of endothelial stimulation with acetylcholine was assessed and compared with that of endothelial independent vasodilation with nitroglycerin. Both drugs were infused into the main renal artery. Renal artery cross-sectional area was measured with intravascular ultrasound and renal blood flow velocity with the aid of an intravascular Doppler technique. RESULTS Both drugs caused a significant and comparable increase in renal artery cross-sectional area (maximal increase [mean +/- SE] 14 +/- 5% with acetylcholine, 15 +/- 5% with nitroglycerin; both changes < 0.05 vs. baseline). Acetylcholine also caused a significant reduction in renal vascular resistance (maximal reduction 55+/- 6%) and increase in renal blood flow (maximal increase 136 +/- 54%). In contrast, nitroglycerin administration showed no significant effect on renal vascular resistance and blood flow. CONCLUSIONS Stimulation of endothelium-derived nitric oxide with acetylcholine results in a significant vasodilatory effect on both conductance and resistance renal blood vessels and leads to a marked reduction in renal vascular resistance and enhancement of renal blood blow. Nitroglycerin, an exogenous nitric oxide donor, caused a selective vasodilatory effect on renal conductance but not on resistance blood vessels and failed to increase renal blood flow. These data suggest the possibility that stimulation of endogenous nitric oxide production in the kidney could be used as a therapeutic target for enhancement of renal flow in patients with heart failure.

Accuracy of determination of changes in cardiac output by transcutaneous continuous-wave doppler computer

The value of a previously validated portable, continuous-wave Doppler computer was assessed for measuring changes in cardiac output (CO). Simultaneous thermodilution and Doppler CO values were measured in triplicate in 16 patients undergoing clinical intervention with vasodilator therapy. A continuous-wave Doppler transducer was placed in the suprasternal notch and directed toward the ascending aorta and angled until the maximal velocity signal was obtained. The correlation coefficient was 0.92 (standard error of the estimate [SEE] = 0.48 liter/min) at rest; with intervention it was 0.88 (SEE = 0.52 liter/min). Our data indicate that the Doppler computer technique, when used in selected patients, is reliable in detecting changes in CO after vasodilator therapy. It may be of value in clinical situations in which hemodynamic monitoring is impractical.

Application of 2-dimensional contrast studies during pericardiocentesis

Two-dimensional echocardiographic contrast studies were performed in 16 patients with pericardial effusion. A 4-chamber view was obtained by positioning the transducer at the apex. The exploratory needle was visualized in 9 patients. Five milliliters of saline solution were injected through the exploring needle and a cloud of echoes indicated its position. Microbubbles were seen in all 16 patients. This technique enabled the operator to identify that the needle was inadvertently in the left ventricle in 2 patients and in the right ventricle in 1. Furthermore, in 2 patients, when fluid could not be aspirated, the contrast study confirmed that the needle was in the pericardial sac; in both cases, pericardial fluid could be aspirated with slight manipulation of the needle. In a patient with a stab wound a negative contrast effect indicated the probable site of laceration. Thus, 2-dimensional contrast echocardiography was useful in locating needle position, which facilitated pericardiocentesis.

Comparison of intracoronary Doppler guide wire and transesophageal echocardiography in measurement of flow velocity and coronary flow reserve in the left anterior descending coronary artery.

BACKGROUND The intracoronary Doppler tipped guide wire has been shown to be highly accurate in the measurement of coronary flow velocity (CFV). Recent studies have indicated that blood flow velocity in the left anterior descending coronary artery (LAD) can be determined by transesophageal echocardiography (TEE). The purpose of this study was to compare flow velocity recordings and coronary flow reserve measurements in the LAD by TEE with those obtained by Doppler guide wire. METHODS AND RESULTS The study population consisted of 14 patients with chest pain and normal coronary arteriograms. After routine coronary arteriography was performed, a 0.014-inch Doppler guide wire was advanced into the proximal part of the LAD. After baseline measurement of coronary flow velocity (CFV) was obtained, 140 microg/kg/min adenosine was administered intravenously for 3 minutes, and the flow velocity was recorded. TEE was performed within 24 hours of the cardiac catheterization. After baseline measurements of CFV in the LAD, heart rate, and blood pressure were obtained, 140 microg/kg/min adenosine was administered intravenously, and the CFV was recorded. Coronary flow reserve was calculated as the ratio of the peak diastolic CFV during adenosine infusion to the peak diastolic CFV at baseline. A good correlation was found (r = 0.91, p < 0.0001) between CFV by Doppler guide wire and that determined by TEE. A good correlation was also found between the coronary flow reserve assessed by Doppler guide wire and that determined by TEE (r = 0.92, p < 0.0001). CONCLUSION Our data indicate that CFV and coronary flow reserve in the LAD can be accurately measured by transesophageal echocardiography.

Chest trauma: Evaluation by two-dimensional echocardiography

Patients with either blunt or penetrating chest injuries may develop a variety of cardiac complications. The studies of 76 patients with suspected cardiac injury obtained over a 30-month period were reviewed in order to determine how frequently and in what manner two-dimensional echocardiography (2DE) is of value in the assessment of such patients. Thirty-nine patients had blunt trauma (group I), and 37 had penetrating trauma (group II). The 2DE findings in group I were: no visible abnormality in 19, pericardial effusions in six, and wall motion abnormalities in two; the studies were technically inadequate in six. In group II patients, the 2DE findings were: no visible abnormality in 14, pericardial effusions in 12, wall motion abnormalities in three, and unusual abnormalities such as foreign body or intrathoracic air in three; the studies were technically inadequate in four. This study shows that satisfactory 2DE can be performed in up to 87% of unselected patients who sustain chest injuries and does provide clinically valuable information that cannot be easily obtained by other noninvasive tests. In this series, 2DE was of greatest value in the detection of pericardial effusions that were present in 27% and of unusual abnormalities including intrathoracic air and foreign bodies such as a bullet.