Ratio of end-systolic stress to end-systolic volume: is it a useful clinical tool?

Cardiac reflections and natural vibrations: force-frequency relation recording system in the stress echo lab

Background

The inherent ability of ventricular myocardium to increase its force of contraction in response to an increase in contraction frequency is known as the cardiac force-frequency relation (FFR). This relation can be easily obtained in the stress echo lab, where the force is computed as the systolic pressure/end-systolic volume index ratio, and measured for increasing heart rates during stress. Ideally, the noninvasive, imaging independent, objective assessment of FFR would greatly enhance its practical appeal.

Objectives

1 – To evaluate the feasibility of the cardiac force measurement by a precordial cutaneous sensor. 2 – To build the curve of force variation as a function of the heart rate. 3 – To compare the standard stress echo results vs. this sensor operator-independent built FFR.

Methods

The transcutaneous force sensor was positioned in the precordial region in 88 consecutive patients referred for exercise, dipyridamole, or pacing stress. The force was measured as the myocardial vibrations amplitude in the isovolumic contraction period. FFR was computed as the curve of force variation as a function of heart rate. Standard echocardiographic FFR measurements were performed.

Results

A consistent FFR was obtained in all patients. Both the sensor built and the echo built FFR identifiy pts with normal or abnormal contractile reserve. The best cut-off value of the sensor built FFR was 15.5 g * 10^-3 (Sensitivity = 0.85, Specificity = 0.77). Sensor built FFR slope and shape mirror pressure/volume relation during stress. This approach is extendable to daily physiological exercise and could be potentially attractive in home monitoring systems.

Left ventricular end-systolic stress/diameter relation as a contractility index and as a predictor of survival. Independence of preload after normalization for end-diastolic diameter

The independence of the slope of the left ventricular (LV) end-systolic stress/end systolic diameter (ESS/ESD) relation of preload (PL) after normalization for end-diastolic diameter (EDD), and the reliability of both the original and the normalized slope as contractility and prognostic indices, were assessed. We studied echocardiographically, hemodynamically, and with carotid pulse tracing, 25 normal subjects, 18 patients with coronary artery disease having a normal ejection fraction (EF), and 30 patients with idiopathic dilated cardiomyopathy (DCM). The arterial pressure was changed with intravenous infusion of phenylephrine. To investigate the effect of PL on the ESS/ESD slope, in 12 normals the PL was decreased with intravenous infusion of 40 mg of furosemide and increased with 1 l isotonic NaCl. The studied population was followed up for 18-61 months. The mean values of the slope after furosemide and after NaCl differed significantly but when the above values were divided by the EDD the differences were nullified. The mean values of the slope differed highly significantly between the three groups. The normalized slope increased the sensitivity in the discrimination. During the follow-up period 10 patients with DCM died. The original and the normalized slopes separated the deceased and survivors significantly (P < 0.002 for both indices) as compared to EF (P < 0.05). The ESS/ESD slope is a very sensitive contractility index and is also superior to EF as a prognostic parameter. The normalization of the slope eliminates its dependence on PL and improves the sensitivity in assessing decreased contractility, although it slightly decreases its prognostic value.

Experimental Human Endotoxemia Is Associated With Depression of Load-Independent Contractility Indices

OBJECTIVE

To evaluate the efficacy of a novel lipopolysaccharide (LPS) antagonist, E5531, in blocking LPS-induced cardiac responses including myocardial depression (as assessed by relatively load-independent echocardiographic indices of contractility) in a human model of experimental endotoxemia.

DESIGN

Randomized, prospective, placebo-controlled, double-blind trial.

SETTING

ICU procedure room.

PARTICIPANTS

Thirty-two healthy, male volunteers.

INTERVENTIONS

Administration of LPS (4 ng/kg) and either a placebo or one of four sequential doses of E5531 (100 microg, 250 microg, 500 microg, or 1,000 microg) followed by volumetric echocardiography before and during 4-L saline solution infusion (3 L over 3 h, followed by 1 L over 2 h).

RESULTS

In addition to the generation of a hyperdynamic circulation throughout the study period, administration of LPS resulted in a biphasic contractility response. Ejection fraction (EF), rate-corrected mean velocity of circumferential fiber shortening (Vcfc), peak systolic BP (SBP)/end-systolic volume index (ESVI) ratio, and end-systolic pressure (Pes)/ESVI ratio increased at the 3-h post-LPS assessment, compared to a control group of subjects receiving only similar amounts of saline solution (minimum p < 0.001). End-systolic myocardial wall stress (sigmaes)/ESVI ratio, one of the most load independent of the contractility indices, was unchanged. At 5 h after endotoxin, EF, Vcfc, SBP/ESVI, Pes/ESVI, and sigmaes/ESVI were all decreased (minimum p < 0.01), indicating myocardial depression. When present, early (3 h after LPS), apparent enhancement of myocardial contractility and later (5 h after LPS) myocardial depression were substantially blunted by administration of E5531 (minimum p < 0.025), typically in a concentration-dependent manner.

CONCLUSIONS

Endotoxin generates significant myocardial depression when measured using highly load-independent indices of cardiac contractility. E5531 is a potent inhibitor of the early hyperdynamic cardiovascular and later myocardial depression response seen in experimental human endotoxemia.

Impact of arterial elastance as a measure of vascular load on left ventricular geometry in hypertension

OBJECTIVE

Effective arterial elastance (Ea), integrating the pulsatile component of left ventricular (LV) afterload, is an estimate of aortic input impedance. We evaluated relationships of Ea with left ventricular anatomy and function in essential hypertension.

DESIGN

A cross-sectional analysis in 81 normotensive and 174 untreated hypertensive individuals enrolled in a referral hypertension centre.

METHODS

Using echocardiography we determined left ventricular mass index (LVMI), relative wall thickness (RWT), stroke volume (SV), endocardial (FSe) and midwall (FSm) fractional shortening and total peripheral resistance (TPR). Carotid pressure waveforms were obtained by arterial tonometry, and end-systolic pressure (Pes) was measured at the dicrotic notch. Ea index (EaI) was calculated as Pes/(SV index); LV elastance (Ees) was estimated as Pes/LV end-systolic volume, and ventriculo-arterial coupling was evaluated by the Ea/Ees ratio.

RESULTS

EaI was higher in hypertensives than in normotensives (3.02 +/- 0.63 versus 2.40 +/- 0.52 mmHg/l per m2; P< 0.0001). Using the 95% upper confidence limit in normotensives, hypertensives were divided in two groups with normal or elevated EaI. The 38 hypertensives with elevated EaI had higher RWT (0.41 +/- 0.06 versus 0.37 +/- 0.05), lower LVMI (87.5 +/- 18.5 versus 96.8 +/- 19.3 g/m2), higher TPR (2247 +/- 408 versus 1658 +/- 371 dynes/cm s(-5)) and lower FSe and FSm (35 +/- 5 versus 39 +/- 5 and 16 +/- 2 versus 18 +/- 2%; all P< 0.05) than patients with normal EaI. Ea/Ees ratio was increased and cardiac output was reduced in hypertensives with elevated EaI.

CONCLUSIONS

High values of EaI identify a minority of hypertensive patients characterized by elevated TPR, left ventricular concentric remodelling, depressed left ventricular systolic function and impaired ventriculo-arterial coupling.

Left ventricular-arterial system coupling at peak exercise in dilated nonischemic cardiomyopathy

We assessed the ventricular-arterial coupling at peak exercise in 20 patients with dilated cardiomyopathy (ejection fraction, 27+/-12%) and 7 normal subjects by radionuclide ventriculography during exercise, coupled with respiratory gas analysis. The end-systolic pressure-volume ratio, taken as an index of contractility, and the effective arterial elastance were calculated at rest and at peak exercise. The end-systolic pressure/volume ratio increased from 3.7+/-2.7 to 6.9+/-4.0 mm Hg/mL at peak exercise in the normal subjects, but did not change significantly (from 0.9+/-0.5 to 1.0+/-0.6 mm Hg/mL) in the patients. Arterial elastance did not change significantly in the patients (+17+/-32%, not significant [NS] vs rest) or in the normal subjects (+22+/-28%, NS vs rest). The change in ejection fraction during exercise correlated both with the end-systolic pressure/volume ratio and with effective arterial elastance changes (r=0.60 and 0.68, respectively). We conclude that ventricular arterial coupling is further altered at peak exercise in these patients because of the lack of increase in contractility and not of altered effective arterial elastance response.

Myocardial dysfunction after resuscitation from cardiac arrest: an example of global myocardial stunning

OBJECTIVES

This study investigated the effect of prolonged cardiac arrest and subsequent cardiopulmonary resuscitation on left ventricular systolic and diastolic function.

BACKGROUND

Cardiac arrest from ventricular fibrillation results in cessation of forward blood flow, including myocardial blood flow. During cardiopulmonary resuscitation, myocardial blood flow remains suboptimal. Once the heart is defibrillated and successful resuscitation achieved, reversible myocardial dysfunction, or "stunning," may occur. The magnitude and time course of myocardial stunning from cardiac arrest is unknown.

METHODS

Twenty-eight domestic swine (26 +/- 1 kg) were studied with both invasive and noninvasive measurements of ventricular function before and after 10 or 15 min of untreated cardiac arrest. Contrast left ventriculograms, ventricular pressures, cardiac output, isovolumetric relaxation time (tau) and transthoracic Doppler-echocardiographic studies were obtained.

RESULTS

Twenty-three of 28 animals were successfully resuscitated and postresuscitation data obtained. Left ventricular ejection fraction showed a significant reduction 30 min after resuscitation (p < 0.05). Regional wall motion analysis revealed diffuse, global left ventricular systolic dysfunction. Left ventricular end-diastolic pressure increased significantly in the postresuscitation period (p < 0.05). Isovolumetric relaxation time (tau) was significantly increased over baseline by 2 h after resuscitation (p < 0.05). Similar findings were noted with the Doppler-echocardiographic analysis, including a reduction in fractional shortening (p < 0.05), a reduction in mitral valve deceleration time (p < 0.05) and an increase in left ventricular isovolumetric relaxation time at 5 h after resuscitation (p < 0.05> By 24 h, these invasive and noninvasive variables of systolic and diastolic left ventricular function had begun to improve. At 48 h, all measures of left ventricular function had returned to baseline levels.

CONCLUSIONS

Myocardial systolic and diastolic dysfunction is severe after 10 to 15 min of untreated cardiac arrest and successful resuscitation. Full recovery of this postresuscitation myocardial stunning is seen by 48 h in this experimental model of ventricular fibrillation cardiac arrest.

Influence of basal nitric oxide secretion on cardiac function in man

1. Nitric oxide is recognised as an important biological mediator, which is thought to be involved in cardiovascular homeostasis. The purpose of this study was to investigate the effects of basal nitric oxide synthesis on cardiac function in man, by blocking nitric oxide synthesis with NG-monomethyl-L-arginine (L-NMMA). 2. Eight normal volunteers were studied on two separate occasions. Measurements of heart rate, blood pressure and echocardiographic indices of left ventricular systolic and diastolic function were made at baseline on each day and every 20 min during incremental infusion of L-NMMA (0.1, 0.2, 0.5, 1.0 and 2.0 mg kg-1 h-1) or placebo. 3. A trend towards reduction in heart rate was observed with L-NMMA infusion although this did not reach statistical significance, whereas significant increases in both systolic blood pressure (at 2.0 mg kg-1 h-1) and systemic vascular resistance index (at 0.5 mg kg-1 h-1) were seen. 4. L-NMMA infusion caused significant reductions in stroke distance and cardiac index, although there was no change in the ratio of end systolic wall stress/end systolic volume index (an afterload independent index of left ventricular systolic performance). 5. The isovolumic relaxation time significantly increased with L-NMMA infusion, together with a significant reduction in the 'E' wave flow velocity integral. Reductions in both peak E/A ratio and E/A flow velocity integral ratio were also seen, although these failed to reach statistical significance. 6. In conclusion, the basal generation of nitric oxide in man appears to maintain a vasodilated state, and modifies left ventricular diastolic filling parameters.

Myocardial dysfunction and abnormal left ventricular exercise response in autonomic diabetic patients

In diabetic patients, the pathophysiologic mechanisms of exercise-induced left ventricular (LV) dysfunction remain controversial. In this study, the role of myocardial contractility recruitment in determining an abnormal LV response to isometric or dynamic exercise has been investigated in 14 diabetic patients with autonomic dysfunction. Ischemic heart disease was excluded by the absence of LV wall motion abnormalities induced by isotonic and isometric exercise and by coronary angiography. Left ventricular and myocardial function were studied at rest, and during isometric and isotonic exercise, by two-dimensional echocardiography; moreover, recruitment of an inotropic reserve was assessed by postextrasystolic potentiation at rest and at peak handgrip. An abnormal response of LV ejection fraction to isometric (9/14) or to dynamic (8/14) exercise was frequent in study patients. In these patients, baseline myocardial contractility was normal, and the significant increase in ejection fraction by postextrasystolic potentiation indicated a normal contractile reserve (65 +/- 7% vs. 74 +/- 6%, p = 0.001). Nevertheless, the downward displacement of LV ejection fraction-systolic wall stress relationships during exercise suggests an inadequate increase in myocardial contractility. However, the abnormal ejection fraction at peak handgrip was completely reversed by postextrasystolic potentiation (67 +/- 6% vs. 58.1 +/- 10%, p = 0.008), a potent inotropic stimulation independent of the integrity of adrenergic cardiac receptors. A defective inotropic recruitment, despite the presence of a normal LV contractile reserve, plays an important role in deexercise LV dysfunction in diabetic patients with autonomic neuropathy.

Serial changes in left and right ventricular systolic and diastolic dynamics during the first year after an index left ventricular Q wave myocardial infarction

OBJECTIVES

This study quantified serially biventricular emptying and filling after infarction and related these to changes in volume, muscle mass, wall stress and contractility.

BACKGROUND

There are limited data on serial changes in ventricular dynamics after infarction.

METHODS

Forty patients had serial electron beam computed tomographic examinations during the first year after index Q wave infarction (21 anterior, 19 inferior), and global biventricular volumes, peak rates of emptying and filling and left ventricular muscle masses were quantified. Mean mid-left ventricular end-systolic wall stresses, rate-corrected velocities of circumferential shortening and two indexes of left ventricular contractility--the end-systolic wall stress/volume ratio and the end-systolic wall stress/rate-corrected velocity of circumferential shortening relation--were estimated in each instance.

RESULTS

Patients with anterior infarction had an increase in biventricular chamber volume of 15% to 35% by 1 year. Global biventricular peak rates of emptying and filling were decreased by 20% to 30% from hospital discharge to 6 weeks but thereafter remained unchanged. Despite a significant increase in mean wall stresses, the end-systolic wall stress/volume ratio remained unchanged during the year. The rate-corrected velocities of circumferential shortening declined serially after anterior infarction but did so in proportion to the increase in mean wall stresses, consistent with no net change in left ventricular contractility. Patients with inferior infarction showed a trend toward similar changes, but the magnitudes did not reach significance.

CONCLUSIONS

Left (and right) ventricular global peak rates of emptying and filling during the first year after infarction can be altered in the absence of additional ischemic injury but are more consistent with responses to changes in left ventricular afterload than changes in intrinsic ventricular performance or contractility. Serial changes in left ventricular afterload after infarction are largely due to progressive chamber enlargement and limited development of compensatory hypertrophy during the first year. Intrinsic global left ventricular contractile performance was not altered by postinfarction cardiac remodeling in the patients examined.

Left ventricular contractility and insulin resistance in essential hypertension

The relationship between fasting insulin as well as the insulin response to an oral glucose tolerance test and echocardiographic cardiac geometry and function was assessed in 55 never-treated lean patients with essential hypertension and normal glucose tolerance and 31 age- and gender-matched normal subjects. The ratio of the area under the curve of the response of insulin and glucose to the oral glucose load was positively correlated with supine heart rate (r values of 0.37) or left ventricular contractility estimated by the end-systolic wall stress to end-systolic volume index ratio and the afterload-corrected fractional shortening (r = 0.59 and 0.36, respectively). No correlation between insulin and left ventricular mass index was observed. When hypertensive patients were divided into those without (n = 39) and with insulin resistance (n = 16), as defined by an elevated value of the ratio of the area under the curve of the response of insulin and glucose, it appeared that both heart rate, end-systolic wall stress to end-systolic volume index ratio and afterload-corrected fractional shortening were higher in patients with insulin resistance, whereas age, arterial pressure, left ventricular mass index, urinary electrolytes, and plasma renin activity were similar in the two groups. These results suggest that increased cardiac systolic performance and heart rate may be associated with insulin resistance in a subset of lean patients with never-treated essential hypertension.

Doppler-derived aortic maximal acceleration. A reliable index of left ventricular systolic function

We compared maximal acceleration of aortic blood flow (aortic Amax), calculated from maximal aortic velocity obtained with a conventional echo-Doppler machine with the invasive inotropic index left ventricular end-systolic pressure/left ventricular end-systolic volume (LVESP/LVESV) ratio and left ventricular ejection fraction (LVEF). Continuous wave (CW) and pulsed wave (PW) Doppler aortic blood flows were recorded from the apical view in 16 patients (age, 62.3 +/- 6.4 years) within 24 h of left-sided catheterization. The theoretical exponential relationship between LVEF and LVESP/LVESV was confirmed in our study population (r = 0.92; p < 0.0001). The relationship between aortic Amax determined either by CW or PW and LVESP/LVESV was linear (r = 0.92 and 0.93, respectively, p < 0.001), whereas the relationship between aortic Amax and angiographic LVEF was exponential (PW: r = 84; CW: r = 0.85; both p < 0.001). We conclude that (1) aortic Amax, derived from maximal velocity obtained with a conventional machine, can be used as an index of left ventricular systolic function, and (2) PW as well as CW Doppler signals can be used for this calculation.

Relation of left ventricular mass, preload, afterload and contractility in pediatric patients with essential hypertension

OBJECTIVES

The aim of this study was to determine if left ventricular preload, afterload or contractility is a correlate of left ventricular mass index in hypertensive pediatric patients.

BACKGROUND

It is believed that decreased contractility and increased preload are associated with left ventricular hypertrophy in adult hypertensive patients.

METHODS

Ninety pediatric hypertensive patients underwent echocardiography to assess left ventricular mass, preload (diastolic dimension and volume) and afterload (end-systolic wall stress, vascular resistance and blood pressure). Contractility was assessed by 1) the end-systolic stress/volume ratio, and 2) the difference between measured and predicted velocity of circumferential fiber shortening. Univariate and multivariate analyses were performed.

RESULTS

Univariate analysis showed significant correlations between left ventricular mass and 1) body mass (r = 0.33, p < 0.001), 2) black race (r = 0.37, p < 0.0003), 3) diastolic dimension (r = 0.26, p < 0.01), 4) diastolic volume (r = 0.20, p < 0.05), and 5) stress/volume ratio (r = -0.53, p < 0.0001) but not the difference between measured and predicted velocity of circumferential fiber shortening. A multivariate model included body mass, age at diagnosis, diastolic dimension, wall stress and vascular resistance but not the difference between measured and predicted velocity of circumferential fiber shortening.

CONCLUSIONS

Contractility is not significantly related to left ventricular mass. The positive correlation between mass and stress/volume may be due to the dependence of the latter variable on loading conditions. We speculate that both elevated preload and systemic vascular resistance may have a role in the development of hypertrophy in hypertensive pediatric patients.

Continuous measurement of left ventricular performance during and after maximal isometric deadlift exercise

BACKGROUND

Isometric exercise produces a reflex increase in arterial blood pressure that is proportional to the intensity and mass of muscle used during contraction. Little is known about the transient effects of heavy weight lifting on left ventricular performance. In this study, we measured continuous changes in left ventricular performance during maximal large-muscle isometric exercise using the standing deadlift position.

METHODS AND RESULTS

Ten healthy young men performed serial deadlifts at 50% of maximal voluntary effort for 90 seconds and 100% of maximal effort for 30 seconds. Echocardiographic imaging (apical four-chamber view), arterial blood pressure (brachial artery catheter), and electrocardiographic monitoring were recorded throughout the deadlift and for 30 seconds of recovery. Aortic flow velocity was also monitored during a separate series of deadlifts. During 100% maximal deadlift, mean arterial pressure increased from 108 +/- 4 to 164 +/- 6 mm Hg. Left ventricular ejection fraction declined initially (from 57 +/- 2% to 49 +/- 3%) at 15 seconds into the lift and recovered (56 +/- 1%) due to significant increases in end-diastolic volume (104 +/- 11 ml to 132 +/- 16 ml) by the end of the lift. The peak systolic pressure/end-systolic volume ratio did not change during the deadlift. After cessation of the deadlift, mean arterial pressure declined precipitously (to 88 +/- 4 mm Hg) within 5 seconds and gradually returned to baseline after 30 seconds. Left ventricular performance indexes all increased significantly during the recovery phase (ejection fraction to 68 +/- 3%, peak systolic pressure/end-systolic volume ratio to 5.9 +/- 0.9). Findings were qualitatively similar for the 50% deadlift.

CONCLUSIONS

During an intense isometric deadlift, left ventricular performance declines initially but is restored by the Frank-Starling mechanism. Upon release of the deadlift, increased left ventricular performance develops in conjunction with a rapid decrease in arterial pressure. The combined effects of increased wall stress during the lift phase and enhanced contractility during the release phase probably contribute to left ventricular hypertrophy associated with repetitive weight training.

Comparison of noninvasive measures of contractility in dilated cardiomyopathy

Left ventricular performance is usually quantified by ejection phase indices such as ejection fraction, cardiac output, and fractional shortening. The load-dependence of these measures may result in inaccurate estimation of intrinsic myocardial contractility in states of chronic pressure or volume overload. End-systolic and stress-shortening relations have been proposed as measures of contractile state insofar as they are theoretically independent of preload and incorporate afterload. This article examines the behavior of these relations in response to changes in loading conditions and contractile state and reviews their application utilizing noninvasive methodology, particularly in the setting of dilated cardiomyopathy.

Changes in structure and function of the human left ventricle after acclimatization to high altitude

To analyse the role of changes in structure and function of the left ventricle in determining cardiac function at rest and during exercise, several two-dimensional and Doppler echocardiographic measurements were performed on 11 healthy subjects immediately before an Himalayan expedition (Nun, 7135 m), during acclimatization (3 weeks) and 14 days after the return. At rest decreases were found in cardiac index (CI) (3.23 l.min-1.m-2, SD 0.4 vs 3.82 l.min-1.m-2, SD 0.58, P less than 0.01), left ventricular mass (55.3 g.m-2, SD 9.4 vs 65.2 g.m-2, SD 13.5, P less than 0.005) and left ventricular end-diastolic volume (LVEDV) (53.9 ml.m-2, SD 6.9 vs 64.8 ml.m-2, SD 9.1, P less than 0.001) after acclimatization; by contrast the coefficient of peak arterial pressure to left ventricular end-systolic volume (PAP/ESV) (7.8, SD 1.6 vs 6.0, SD 1.8, P less than 0.005) and mean wall stress [286 kdyn.cm-2, SD 31 vs 250 kdyn.cm-2, SD 21 (2.86 N.cm-2, SD 0.31 vs 2.50 N.cm-2, SD 0.21), P less than 0.005] increased. After return to sea level, low values of CI and mass persisted despite a return to normal of LVEDV and preload. A reduction of PAP/ESV was also observed. At peak exercise, PAP/ESV (8.7, SD 2.4 vs 12.8, SD 2.0, P less than 0.0025), CI (9.8 l.min-1.m-2, SD 2.5 vs 11.6 l.min-1.m-2, SD 1.6, P less than 0.05) and the ejection fraction (69%, SD 6 vs 76%, SD 4, P less than 0.05) were lower after return to sea level than before departure.(ABSTRACT TRUNCATED AT 250 WORDS)

Ability of left ventricular stress-shortening relations, end-systolic stress/volume ratio and indirect indexes to detect severe contractile failure in ischemic or idiopathic dilated cardiomyopathy

The ability of several proposed indirect and direct indexes of left ventricular LV) systolic performance and contractility to detect clinically important LV dysfunction was evaluated in 42 patients with refractory dilated cardiomyopathy studied with right-sided heart catheterization and M-mode echocardiography. Hemodynamic evaluation demonstrated elevated filling pressure (mean pulmonary artery wedge pressure 24 +/- 6 mm Hg) and depressed function (cardiac index 1.68 +/- 0.43 liters/min/m2). Echocardiographic LV end-diastolic dimension (7.3 +/- 1.0 cm), mass (182 +/- 60 gm/m2) and end-systolic stress (163 +/- 44 x 10(3) dynes/cm2) were increased whereas fractional shortening was depressed in all (mean 12 +/- 4%). During follow-up 88% of patients died at a median interval of 16 months after study. Indirect measurements of LV function (mitral E point-septal separation and the ratio of preejection period to LV ejection time) were abnormal in 100 and 88% of patients, respectively. Contractility was classified as depressed in 36 (86%) patients by the end-systolic stress volume index ratio and in 31 (74%) by the relation between fractional shortening and end-systolic stress. In contrast, the relation between end-systolic stress and velocity of circumferential shortening identified only 7 (17%) patients as having subnormal contractility and classified 9 (21%) as having supernormal contractility. Rate correction of velocity of circumferential shortening only modestly improved the ability of the relation to identify depressed contractility (abnormal in 16 patients or 38 percent).