Doppler echocardiographic evaluation of left ventricular function

Invasive measurements of maximum acceleration of aortic blood flow are sensitive indicators of left ventricular function. Doppler echocardiography provides noninvasive measurements of aortic blood flow acceleration. Our studies establish the accuracy of Doppler-derived indices of aortic blood flow velocity for evaluation of left ventricular function. Doppler-derived peak velocity and mean acceleration showed excellent correlation with invasively measured peak left ventricular dP/dt and maximum aortic blood flow (dQ/dt) under varying heart rate, preload, afterload, and inotropic states. Similar correlations were observed between Doppler-derived peak velocity and mean acceleration and invasively measured left ventricular dP/dt and dQ/dt under conditions of varying degrees of myocardial ischemia. Thus, Doppler echocardiography provides an accurate noninvasive method to evaluate left ventricular performance.     

Effects of labetalol on left ventricular mass and function in hypertension--an assessment by serial echocardiography

We determined echocardiographic (M-mode) indices of left ventricular mass and function serially at 1-month intervals in 10 patients with uncomplicated mild or moderate essential hypertension, before and after adequate control of blood pressure with labetalol, a combined alpha- and beta-receptor blocking agent. Seven patients had pretreatment echocardiographic evidence of left ventricular hypertrophy with disproportionate septal thickness in 4. Systolic blood pressure in the untreated state correlated well (r = 0.96) with left ventricular mass but poorly (r = 0.30) with diastolic pressure. Following a satisfactory blood pressure reduction, achieved in all patients, left ventricular mass decreased from 240.5 +/- 71.1 g to 159.5 +/- 40.7 g (P less than 0.01), interventricular septal thickness from 1.33 +/- 0.3 cm to 0.92 +/- 0.25 cm (P less than 0.01) and posterior wall thickness from 1.03 +/- 0.23 cm to 0.93 +/- 0.23 cm (P less than 0.05). While the maximum changes in left ventricular mass were noted by the end of first month (P less than 0.01) with insignificant changes thereafter, the correlation of fall in blood pressure with change in left ventricular mass was significant only after 2 months of treatment (P less than 0.05). Indices of left ventricular function (end-diastolic volume, ejection fraction, fractional diameter shortening, left atrial dimension and posterior aortic wall motion) were normal before treatment and remained unchanged during 3 months of treatment. In this short-term study, labetalol reduced left ventricular hypertrophy (expressed as left ventricular mass and wall thickness) without altering left ventricular function indices in patients with uncomplicated essential hypertension. This has important implications in the treatment of hypertensive patients.     

Comparative studies of the systemic hemodynamics and myocardial oxygen consumption of FRC 8653, a new Ca++ channel blocker, and nifedipine in anesthetized dogs.

Effects of FRC 8653, a new dihydropyridine derivative, on regional blood flow, cardiac function and myocardial oxygen consumption were examined and compared with those of nifedipine in anesthetized open-chest dogs. Intravenous administration of FRC 8653 at doses of 1, 3 and 10 micrograms/kg dose-dependently decreased aortic pressure and increased aortic, vertebral and coronary blood flow similar to nifedipine. No significant change was observed in left ventricular end-diastolic pressure, left ventricular positive dP/dt and heart rate following i.v. administration of FRC 8653. Myocardial oxygen consumption was dose-dependently decreased by FRC 8653. When changes in mean aortic pressure and aortic and coronary blood flow were compared at the same dose of 10 micrograms/kg i.v., both FRC 8653 and nifedipine showed almost the same degree of reduction of mean aortic pressure, but the time from drug administration to peak responses and the duration for which half the maximal effects were maintained, were significantly longer with FRC 8653 than nifedipine. Results suggest that FRC 8653 may be useful for the treatment of patients with hypertension and ischaemic heart disease.     

Assessment of left ventricular function by indices derived from aortic flow velocity.

The velocity and acceleration of aortic blood flow were measured by means of a catheter velocity probe in 40 patients during routine diagnostic cardiac catheterization. Ten different variables were derived from the aortic velocity measurements, and their ability to discriminate between good and bad left ventricular (LV) function was tested. By means of eight conventional indices of LV function derived from pressure, mean flow, and quantitative cineangiography, the patients were divided into 3 groups: group 1, good LV function; group 2, moderate LV function; group 3, poor LV function. Aortic peak velocity and maximal acceleration correlated well with stroke volume and were thus indices of LV pump function. Aortic peak velocity also showed a significant correlation with LV stroke work. Both aortic peak velocity and maximal acceleration failed to discriminate between the three groups of patients, and correlated poorly with conventional indices of LV function. The mean values of stroke volume differed significantly between groups 1 and 2, and between groups 1 and 3, and also correlated better with the conventional functional indices. The best discrimination between normal and abnormal LV function was provided by dividing stroke volume by maximal acceleration, but stroke volume divided by peak velocity discriminated better than stroke volume alone. Stroke volume divided by maximal acceleration also gave more significant individual correlations with the conventional functional indices than did any other variable derived from aortic velocity.     

Assessment of left ventricular function by indices derived from aortic flow velocity.

The velocity and acceleration of aortic blood flow were measured by means of a catheter velocity probe in 40 patients during routine diagnostic cardiac catheterization. Ten different variables were derived from the aortic velocity measurements, and their ability to discriminate between good and bad left ventricular (LV) function was tested. By means of eight conventional indices of LV function derived from pressure, mean flow, and quantitative cineangiography, the patients were divided into 3 groups: group 1, good LV function; group 2, moderate LV function; group 3, poor LV function. Aortic peak velocity and maximal acceleration correlated well with stroke volume and were thus indices of LV pump function. Aortic peak velocity also showed a significant correlation with LV stroke work. Both aortic peak velocity and maximal acceleration failed to discriminate between the three groups of patients, and correlated poorly with conventional indices of LV function. The mean values of stroke volume differed significantly between groups 1 and 2, and between groups 1 and 3, and also correlated better with the conventional functional indices. The best discrimination between normal and abnormal LV function was provided by dividing stroke volume by maximal acceleration, but stroke volume divided by peak velocity discriminated better than stroke volume alone. Stroke volume divided by maximal acceleration also gave more significant individual correlations with the conventional functional indices than did any other variable derived from aortic velocity.     

Instantaneous force-velocity-length relations in the intact human heart

The contractile state of the left ventricle was analyzed in 10 patients using measurements of instantaneous ascending aortic blood flow velocity, left ventricular pressure and end-diastolic volume. Instantaneous left ventricular volume at 10 msec intervals was derived by subtracting the cumulative volumes (integral of flow) ejected during each sampling interval from angiographically derived end-diastolic volume. Circumferential fiber shortening velocity and wall force were calculated as flow rate/4πr² and left ventricular pressure × πr², respectively. The instantaneous radius (r) was calculated by assuming a spherical model for the left ventricle. Applying a Hill model for muscle contraction, contractile element velocity was calculated as the sum of circumferential fiber shortening velocity and series elastic element velocity. Series elastic element velocity was calculated from the time rate of change of wall force (dF/dt) and series elastic element stiffness.     

The effect of regional myocardial ischemia on Doppler echocardiographic indexes of left ventricular performance: influence of heart rate, aortic blood pressure, and the size of the ischemic zone

Doppler echocardiographic indexes of ascending aortic blood flow velocity have been found to be an effective method of assessing changes in left ventricular performance induced by myocardial ischemia in both experimental animal preparations and in patients. In eight opened-chest anesthetized dogs, we investigated the influence of heart rate, aortic blood pressure, and size of the ischemic zone on Doppler indexes during regional myocardial ischemia. With control of mean aortic blood pressure and heart rate, transient coronary artery occlusion resulted in a statistically significant decline in peak velocity and mean velocity when as little as 24% of left ventricular myocardium was rendered ischemic. However, when heart rate and mean aortic blood pressure were not controlled, significant declines in peak velocity and mean velocity occurred only with simultaneous two-vessel occlusions involving greater than 47% of left ventricular myocardium. Although transient coronary artery occlusions generally produced no significant change in heart rate in the absence of atrial pacing, significant declines in aortic blood pressure were observed. We conclude that Doppler indexes of left ventricular performance obtained during myocardial ischemia are influenced not only by the extent of myocardium rendered ischemic, but also by changes in mean aortic blood pressure.     

Acute haemodynamic and metabolic effects of dopexamine, a new dopaminergic receptor agonist, in patients with chronic heart failure.

Dopexamine, a new compound with postjunctional dopamine receptor activating and beta adrenoceptor agonist properties, was given to 10 patients with chronic heart failure at diagnostic cardiac catheterisation to investigate its acute haemodynamic and metabolic effects. The drug was administered by intravenous infusion in three incremental doses and produced significant dose related increases in cardiac index, stroke volume index, and heart rate and falls in systemic vascular resistance and left ventricular end diastolic pressure; aortic and pulmonary artery pressures were unchanged. Isovolumic phase (max dP/dt and KVmax) and ejection phase (peak aortic blood velocity, maximum acceleration of blood, and maximum rate of change of power with time during ejection) indices of myocardial contractility were all increased by dopexamine but these changes were hard to interpret in the presence of an increase in heart rate. Myocardial efficiency and ejection fraction were both increased and left ventricular end diastolic and end systolic volumes fell. These largely beneficial changes were achieved without a statistically significant increase in myocardial oxygen consumption or disturbance of myocardial metabolic function. Dopexamine was well tolerated but tremor was reported by two patients at the intermediate dose and mild chest pain by two patients at the high dose.     

Acute haemodynamic and metabolic effects of dopexamine, a new dopaminergic receptor agonist, in patients with chronic heart failure

Dopexamine, a new compound with postjunctional dopamine receptor activating and beta adrenoceptor agonist properties, was given to 10 patients with chronic heart failure at diagnostic cardiac catheterisation to investigate its acute haemodynamic and metabolic effects. The drug was administered by intravenous infusion in three incremental doses and produced significant dose related increases in cardiac index, stroke volume index, and heart rate and falls in systemic vascular resistance and left ventricular end diastolic pressure; aortic and pulmonary artery pressures were unchanged. Isovolumic phase (max dP/dt and KVmax) and ejection phase (peak aortic blood velocity, maximum acceleration of blood, and maximum rate of change of power with time during ejection) indices of myocardial contractility were all increased by dopexamine but these changes were hard to interpret in the presence of an increase in heart rate. Myocardial efficiency and ejection fraction were both increased and left ventricular end diastolic and end systolic volumes fell. These largely beneficial changes were achieved without a statistically significant increase in myocardial oxygen consumption or disturbance of myocardial metabolic function. Dopexamine was well tolerated but tremor was reported by two patients at the intermediate dose and mild chest pain by two patients at the high dose.     

Comparison of electrocardiographic and echocardiographic measures of left ventricular hypertrophy in the assessment of aortic stenosis

One hundred and nineteen patients with a clinical diagnosis of important aortic stenosis were assessed clinically and by electrocardiography and M mode echocardiography to determine the degree of left ventricular hypertrophy. Predicted left ventricular pressure was calculated from two previously described formulas. Comparisons were made between the various methods for assessing left ventricular hypertrophy to see which method most reliably predicted the severity of the stenosis as defined by invasive measurement of left ventricular pressure and peak aortic valve gradient. Direct measurement of left ventricular wall thickness from the echocardiogram, expressed as the mean of septal and posterior wall thickness, was the most accurate predictor (r = 0.75 for 29 patients with high quality echocardiograms), and surpassed derived indices (left ventricular mass (r = 0.68) and predicted left ventricular pressure derived from the two formulas (r = 0.39 and r = 0.68)) in adults. Echocardiographic results were significantly better than electrocardiographic, but only when the recordings were of very high quality. Average quality echocardiograms were no better than precordial electrocardiographic voltages for predicting the severity of aortic stenosis. The formulas for predicting left ventricular pressure were of more value in children than in adults, but they were still not sufficiently accurate to be predictive in individual cases. Electrocardiographic voltages were more accurate predictors of the severity of aortic stenosis in children than in adults.     

Comparison of electrocardiographic and echocardiographic measures of left ventricular hypertrophy in the assessment of aortic stenosis.

One hundred and nineteen patients with a clinical diagnosis of important aortic stenosis were assessed clinically and by electrocardiography and M mode echocardiography to determine the degree of left ventricular hypertrophy. Predicted left ventricular pressure was calculated from two previously described formulas. Comparisons were made between the various methods for assessing left ventricular hypertrophy to see which method most reliably predicted the severity of the stenosis as defined by invasive measurement of left ventricular pressure and peak aortic valve gradient. Direct measurement of left ventricular wall thickness from the echocardiogram, expressed as the mean of septal and posterior wall thickness, was the most accurate predictor (r = 0.75 for 29 patients with high quality echocardiograms), and surpassed derived indices (left ventricular mass (r = 0.68) and predicted left ventricular pressure derived from the two formulas (r = 0.39 and r = 0.68)) in adults. Echocardiographic results were significantly better than electrocardiographic, but only when the recordings were of very high quality. Average quality echocardiograms were no better than precordial electrocardiographic voltages for predicting the severity of aortic stenosis. The formulas for predicting left ventricular pressure were of more value in children than in adults, but they were still not sufficiently accurate to be predictive in individual cases. Electrocardiographic voltages were more accurate predictors of the severity of aortic stenosis in children than in adults.     

Relationship between age, body size, gender, and blood pressure and Doppler flow measurements in the aorta and pulmonary artery

Previous studies have demonstrated a relationship between both age and body surface area (BSA) and M-mode echocardiographic measurements of left ventricular, left atrial, and aortic root dimensions and left ventricular wall thickness. We evaluated the relationships between age, BSA, gender and blood pressure, and Doppler aortic and pulmonary artery (PA) flow velocity measurements in 97 adults, aged 21 to 78 years, without clinical evidence of cardiac disease. No significant relationship was found between gender or blood pressure and aortic or PA flow velocity measurements. Aortic peak flow velocity, flow velocity integral, and average acceleration decreased with increasing age (all p less than 0.001), whereas ejection time (corrected for heart rate) increased, and acceleration time did not change. In contrast, there was no relationship between age and Doppler PA flow velocity measurements. Although there was no relationship between BSA and Doppler aortic flow measurements, PA peak flow velocity and average acceleration increased, while acceleration time decreased with increasing BSA (all p less than 0.02). Decreases in aortic peak flow velocity and flow velocity integral may be partly related to known increases in aortic root diameter with aging. The relationship between PA flow velocity measurements and BSA is not readily explained.     

The effect of positive end-expiratory pressure on the coronary blood flow

Positive end-expiratory pressure (PEEP) is used liberally whenever a ventilated patient shows signs of increased pulmonary venous shunting. Clinicians using PEEP to improve blood oxygenation may face the cardiovascular side effects which limit utilization of the desired respiratory effects of PEEP. We measured the pressure flow characteristics of the cardiovascular system and the coronary arterial system as a function of PEEP, using closed-chest surgically instrumented dogs, in order to assess its effects on myocardial blood flow with respect to the left ventricular energy demands. The aortic left ventricular blood pressure as well as the aortic blood flow decreased with increasing PEEP values. The coronary blood flow decreased by 5% for PEEP values of 4 cm H2O, and by 25% for 14 cm H2O of PEEP. PEEP values under 10 cm H2O reduced the left ventricular end-diastolic pressure (LVEDP), while higher PEEP values caused an increase in LVEDP. The relation between the alterations of coronary and aortic blood flows changed with PEEP values. Low PEEP values (less than 10 cm H2O) had a tendency for higher relative reduction of aortic blood flow, whereas higher PEEP values (higher than 10 cm H2O) reduced the coronary blood flow more than the reduction occurring in the aortic blood flow. Our results suggest that low PEEP values may have beneficial effects on the relation between aortic blood flow and coronary blood flow, therefore low PEEP application may minimize hypoxic myocardial alterations. Further studies that will measure left ventricular workload or another metabolic index for estimating myocardial perfusion relative to its metabolic demand are essential before clinical conclusions can be drawn from our results.     

Acute haemodynamic effects of nifedipine in patients with ventricular septal defect

The haemodynamic effects of nifedipine were studied in 14 patients (aged 8-14 years, seven male and seven female) with ventricular septal defect with and without pulmonary hypertension. All underwent left and right heart catheterisation. In each patient the pressures and heart rate were measured and blood samples were taken for oximetry before and after sublingual administration of 10 mg nifedipine. In eight patients with ventricular septal defect without pulmonary hypertension (mean pulmonary artery pressure less than 20 mm Hg) nifedipine significantly reduced the mean aortic pressure and systemic vascular resistance, and significantly increased heart rate. The other haemodynamic indices did not change significantly. In six patients with ventricular septal defect complicated by pulmonary hypertension (mean pulmonary artery pressure greater than 20 mm Hg) nifedipine significantly increased systemic output, stroke volume, and heart rate, and significantly reduced systemic vascular resistance and the pulmonary to systemic flow ratio. The other haemodynamic indices did not change significantly. Nifedipine had a beneficial effect in patients with ventricular septal defect complicated by pulmonary hypertension. It reduced the left to right shunt and increased the stroke volume. This effect was not seen in patients with ventricular septal defect uncomplicated by pulmonary hypertension.     

Acute haemodynamic effects of nifedipine in patients with ventricular septal defect.

The haemodynamic effects of nifedipine were studied in 14 patients (aged 8-14 years, seven male and seven female) with ventricular septal defect with and without pulmonary hypertension. All underwent left and right heart catheterisation. In each patient the pressures and heart rate were measured and blood samples were taken for oximetry before and after sublingual administration of 10 mg nifedipine. In eight patients with ventricular septal defect without pulmonary hypertension (mean pulmonary artery pressure less than 20 mm Hg) nifedipine significantly reduced the mean aortic pressure and systemic vascular resistance, and significantly increased heart rate. The other haemodynamic indices did not change significantly. In six patients with ventricular septal defect complicated by pulmonary hypertension (mean pulmonary artery pressure greater than 20 mm Hg) nifedipine significantly increased systemic output, stroke volume, and heart rate, and significantly reduced systemic vascular resistance and the pulmonary to systemic flow ratio. The other haemodynamic indices did not change significantly. Nifedipine had a beneficial effect in patients with ventricular septal defect complicated by pulmonary hypertension. It reduced the left to right shunt and increased the stroke volume. This effect was not seen in patients with ventricular septal defect uncomplicated by pulmonary hypertension.     

Study of the value of corrected ejection fraction in the evaluation of left ventricular function in patients with mitral or aortic regurgitation

Evaluation of left ventricular function in the presence of valvular regurgitation is still a clinical problem because ejection phase indices including ejection fraction are heavily dependent on preload and afterload and cannot be regarded as reliable indices of contractility in diseases associated with altered loading conditions. The authors attempted to evaluate the usefulness of the new index-corrected ejection fraction in the evaluation of left ventricular (LV) function in patients with chronic mitral (MR) or aortic regurgitation (AR). The study included 21 patients with chronic severe MR (11 patients) and AR (10 patients) with a mean age of 18 years. All patients underwent valve replacement or repair. Echo Doppler study was performed preoperatively and postoperatively and included measurement of the following LV parameters: end-diastolic dimension (EDD), end-diastolic volume (EDV), end-systolic dimension (ESD), end-systolic volume (ESV), ejection fraction (EF), systolic blood pressure/end-systolic dimension (SBP/ESD); also mitral and aortic stroke volume were calculated cross-sectional area (CSA) x time velocity integral TVI. Corrected ejection fraction (EFc) was derived from the following equation: EFc = [EF + square root of (ASV x MSV) / EDV] / 2. The mean preoperative EFc did not change significantly after surgical correction of mitral or aortic regurgitation. Preoperative EFc did not show significant difference compared with postoperative EF in the two groups. Preoperative EFc correlated significantly with other preoperative and postoperative indices of LV function. Postoperative EFc showed very close correlation with other postoperative parameters. Thus, using the new index-corrected ejection fraction in the assessment of LV function in patients with mitral or aortic regurgitation has several advantages: Noninvasive, independent of loading changes, helpful in predicting the immediate postoperative clinical course, and a reliable index for evaluation of LV systolic function preoperatively and postoperatively.     

Effects of nicardipine on left ventricular function and energetics in man

The effects of nicardipine, a new dihydropyridine calcium antagonist, on left ventricular function and energetics were studied in 13 patients. Nicardipine was administered as a 2 mg bolus (i.v.) followed by an infusion titrated to maintain a 10–20 mm Hg decrease in systolic pressure. Nicardipine increased heart rate 19% (P < 0.001) while left ventricular end-diastolic pressure was not significantly changed and stroke volume (ml) increased 13% (P < 0.01). Peak values for the first and second time derivatives of left ventricular pressure were increased by 26% (P < 0.01) and 50% (P < 0.02) respectively. Peak aortic blood flow, peak aortic blood acceleration, and the peak rate of change of ejection power were increased 86% (P < 0.001), 123% (P < 0.01), and 113% (P < 0.001), respectively. Stroke work was not changed during nicardipine infusion. External power increased by 40% (P < 0.01); however, the ratio of oscillatory to total power was not significantly different. Although the product of heart rate and systolic aortic pressure was not significantly altered with nicardipine, myocardial oxygen consumption increased 18% (P < 0.02) with a disproportionate increase in coronary blood flow of 41% (P < 0.001) and decrease in coronary resistance of 39% (P < 0.001). The time constant for left ventricular isovolumic relation decreased 22% (P < 0.001) during nicardipine infusion while the minimum value of dP/dt was unchanged. Thus, when administered intravenously in man, nicardipine is a potent coronary and systemic vasodilator producing reflex tachycardia, increased indices of myocardial contractile state, and improved isovolumic relaxation with an associated increase in myocardial oxygen consumption.     

Ascending aortic blood pressure-derived indices are not correlated with the extent of coronary artery disease in patients with impaired left ventricular function

BACKGROUND: Ascending aortic blood pressure-derived indices were shown to be related to coronary atherosclerosis. Unfortunately, most studies published so far included patients with preserved left ventricular function. Therefore, the aim of the present study was to investigate the relation between ascending aortic blood pressure-derived indices and the extent of coronary atherosclerosis in patients with impaired left ventricular function. METHODS: The study group consisted of 375 patients (302 men and 73 women; mean age: 59.0+/-10.1 years) with angiographically confirmed coronary artery disease and ejection fraction < or =55%. Invasive ascending aortic blood pressure during catheterization and conventional sphygmomanometer measurements were taken. RESULTS: None of the brachial or aortic blood pressure-derived indices differed between patients with one-, two- and three-vessel coronary artery disease. They were not independently related to the risk of having three-vessel coronary artery disease in none of the constructed models in logistic regression analysis. Moreover, none of the studied indices was correlated with Gensini or severity scores. We also did not find any significant correlation between blood pressure-derived indices and extent of coronary atherosclerosis in patients with ejection fraction < or =25%, 25-40% or >40%. CONCLUSION: Ascending aortic blood pressure-derived indices are not correlated with the severity of coronary atherosclerosis in patients with coronary artery disease and impaired left ventricular function.     

Left ventricular blood flow during aortic pressure reduction in hypertensive dogs.

We measured left ventricular blood flow with radioactive microspheres during aortic pressure reduction in 10 open-chest, anesthetized dogs with left ventricular hypertrophy due to chronic hypertension and in 10 matched normotensive dogs. Heart rate and left atrial pressure were held constant, and autonomic reflexes were abolished with ganglionic blockade. Aortic diastolic pressure was lowered from baseline to 90, 75, and 60 mm Hg with an arteriovenous fistula. During aortic pressure reduction, a stepwise decline in the endocardial-to-epicardial flow ratio in hypertrophied hearts from 1.23 +/- 0.04 at baseline to 0.96 +/- 0.09 at a diastolic pressure of 75 mm Hg parallelled that in normal hearts and was not associated with any deterioration in left ventricular performance. However, a further fall in the endocardial-to-epicardial flow ratio to 0.76 +/- 0.10 at a diastolic pressure of 60 mm Hg in hypertrophied hearts exceeded that in normal hearts (0.92 +/- 0.05, p less than 0.05) and was accompanied by evidence of left ventricular isovolumic and end-systolic dysfunction. We conclude that in hearts with pressure-overload left ventricular hypertrophy, aortic pressure reduction causes a transmural blood flow redistribution from subendocardial to subepicardial muscle layers. At moderately low aortic pressures, this redistribution is more pronounced than in normal hearts and is associated with functional evidence of myocardial ischemia.     

Evaluation of a theoretical Doppler index to noninvasively estimate peak dP/dt using continuous wave Doppler ultrasound of ascending aortic flow in man

A theoretical formula for calculation of peak dP/dt was derived using parameters obtained from continuous wave Doppler echocardiography signals of aortic blood flow. The direct proportional relationship between the main variables of this formula and invasively measured peak dP/dt was validated in 20 patients undergoing routine diagnostic cardiac catheterization. Doppler signals of aortic flow were obtained simultaneously to invasive pressure recordings with a 2 MHz continuous wave transducer via the suprasternal echocardiographic window. The Doppler signals were recorded on magnetic tape and measurements were made with digital calipers by two independent, blinded observers. The following parameters were measured: peak velocity (V) and time from onset of ejection to peak velocity (T). V2/T, the variable of the derived formula, was calculated for each of the observer's measured parameters and showed a very high interobserver correlation. The two observers' measurements of each parameter were averaged for each patient and the resulting mean was used in calculating the V2/T and mean acceleration. 4. A good correlation of V2/T with invasively measured peak dP/dt was obtained. Our derived index of left ventricular function showed a higher correlation with peak dP/dt compared to other Doppler indices of ventricular function. V2/T may provide a noninvasive method for estimating peak dP/dt.