Evaluation of relationship between myocardial contractile state and left ventricular function in patients with aortic regurgitation

Medical treatment of asymptomatic chronic aortic regurgitation

Chronic aortic regurgitation results in left ventricular (LV) dilation, increased LV work and, eventually, a decline in LV function and heart failure. An important question is whether pharmacological therapy could preserve LV function and delay the need for aortic valve replacement. Vasodilators have a number of theoretical advantages. By lowering blood pressure, they reduce the regurgitant volume and decrease LV afterload. This article summarizes the clinical studies that have evaluated vasodilators in asymptomatic patients with chronic aortic regurgitation. Some studies suggest favorable effects on LV function and clinical outcomes, but results are inconsistent, making it difficult to draw definite conclusions. In general, studies have been too small to reliably evaluate the overall benefits and risks of this treatment, and in several studies there was no significant difference in measured blood pressure by treatment allocation. For these reasons, decisions on whether vasodilators are indicated in individual patients must currently be based on clinical judgment alone.

Operative contractility: A functional concept of the inotropic state

1. Initial unsuccessful attempts to evaluate ventricular function in terms of the 'heart as a pump' led to focusing on the 'heart as a muscle' and to the concept of myocardial contractility. However, no clinically ideal index exists to assess the contractile state. The aim of the present study was to develop a mathematical model to assess cardiac contractility. 2. A tri-axial system was conceived for preload (PL), afterload (AL) and contractility, where stroke volume (SV) was represented as the volume of the tetrahedron. Based on this model, 'operative' contractility ('OperCon') was calculated from the readily measured values of PL, AL and SV. The model was tested retrospectively under a variety of different experimental and clinical conditions, in 71 studies in humans and 29 studies in dogs. A prospective echocardiographic study was performed in 143 consecutive subjects to evaluate the ability of the model to assess contractility when SV and PL were measured volumetrically (mL) or dimensionally (cm). 3. With inotropic interventions, OperCon changes were comparable to those of ejection fraction (EF), velocity of shortening (Vcf) and dP/dt-max. Only with positive inotropic interventions did elastance (Ees) show significantly larger changes. With load manipulations, OperCon showed significantly smaller changes than EF and Ees and comparable changes to Vcf and dP/dt-max. Values of OperCon were similar when AL was represented by systolic blood pressure or wall stress and when volumetric or dimensional values were used. 4. Operative contractility is a reliable, simple and versatile method to assess cardiac contractility.

Afterload reduction in severe aortic regurgitation

This study was designed to assess the effects of afterload reduction in asymptomatic patients with severe aortic regurgitation (AR) and maintained LV function by cine-MRI. We studied 13 patients at baseline and after 0.2 mg/kg Hydralazine (I.V.). Patients were stratified according to the volumetric LV response to acute afterload reduction: Group I comprised patients with improved LV response; Group II comprised patients with unchanged or deteriorated LV response. Baseline LV function and severity of AR were not significantly different between groups. However, regurgitant fraction decreased (50 +/- 12 vs. 36 +/- 9%; P < 0.03) and cardiac output increased (4.9 +/- 1.4 vs. 7.1 +/- 1.6l/minute; P < 0,001) in Group I and remained unchanged in Group II (54 +/- 10 vs. 55 +/- 10%, P = n.s. and 5.5 +/- 1.4 vs. 6.6 +/- 0.9l/minute; P = n.s.) during maximal vasodilation. Beat-to-beat analysis revealed a decrease of left ventricular endsystolic volume index in group I (48 +/- 13 vs. 37 +/- 9 ml/beat; P < 0.05) and no change in group II (61 +/- 20 vs. 62 +/- 20 ml/beat; P = n.s.). In the natural history of chronic AR, the absence of improved LV performance during acute vasodilation using beat-to-beat analysis by MRI may identify patients with more advanced cardiac adaptation to chronic volume overload.

Assessment of left ventricular long axis contraction can detect early myocardial dysfunction in asymptomatic patients with severe aortic regurgitation

OBJECTIVE

To identify variables that could be applied at rest to diagnose subclinical ventricular dysfunction in asymptomatic patients with severe aortic regurgitation.

DESIGN

Cross sectional study.

PATIENTS

Left ventricular long axis contraction was studied using tissue Doppler and M mode echocardiography in 21 patients with no symptoms (New York Heart Association (NYHA) functional class </= 2a) but severe aortic regurgitation (jet area/left ventricular outflow tract area > 40%).

MAIN OUTCOME MEASURES

Left ventricular ejection fraction (LVEF) at baseline and peak exercise (Weber protocol), cardiopulmonary function, and left ventricular long axis function at rest (peak systolic velocity and excursion of the mitral annulus).

RESULTS

In 11 patients, ejection fraction increased or did not change (from mean (SD) 55 (5)% to 58 (4)%, p < 0.05) (group I); in 10 patients it decreased by > 5% (from 54 (4)% to 42 (5)%, p < 0.001) (group II). Exercise ejection fraction was < 50% in all patients in group II. At rest, there were no differences between the groups in ejection fraction, left ventricular diameter indices, wall stress, and short axis contraction. However, patients in group II had reduced long axis contraction compared with group I: peak systolic velocity 8.6 (0.6) v 11.9 (2.2) cm/s (p < 0.001); excursion 11 (2) v 14 (2) mm (p < 0.01). A resting velocity of < 9.5 cm/s was the best indicator of poor exercise tolerance (sensitivity 90%, specificity 100%).

CONCLUSIONS

Markers of reduced long axis contraction may provide simple and reliable indices of subclinical left ventricular dysfunction in asymptomatic patients with severe aortic regurgitation.

Chronic aortic regurgitation. Role of medical therapy and optimal timing for surgery

Aortic valve replacement should be performed once significant symptoms develop. Lacking important symptoms, operation should also be performed in patients with aortic regurgitation who manifest consistent and reproducible evidence of either LV contractile dysfunction at rest or extreme LV dilation. Noninvasive imaging techniques should play a major role in this evaluation. An important clinical decision, such as recommending aortic valve replacement in the asymptomatic patient, should not be based on a single echocardiographic or radionuclide angiographic measurement alone. When these data consistently indicate impaired contractile function at rest or extreme LV dilation on repeat measurements, however, operation is indicated in the asymptomatic patient. This strategy should reduce the likelihood of irreversible LV dysfunction in these patients and enhance long-term postoperative survival.

Integrated MR imaging approach to valvular heart disease

With development of cine and velocity encoded magnetic resonance imaging, it is now feasible to detect and quantify aortic and mitral stenosis and regurgitation accurately. In addition, magnetic resonance imaging has the capabilities to assess simultaneously left and right ventricular mass, volumes, and function precisely. The high accuracy and reproducibility of magnetic resonance imaging in quantification of regurgitation and ventricular function has the potential to provide improved monitoring of therapy and optimal timing of surgery in patients with valvular dysfunction. In comparison to echocardiography and angiography, some current limitations of magnetic resonance imaging to an integrated approach of valvular heart disease exist, which may be removed with future refinement of magnetic resonance imaging technology for cardiovascular imaging.

Prediction of indications for valve replacement among asymptomatic or minimally symptomatic patients with chronic aortic regurgitation and normal left ventricular performance

BACKGROUND

Optimal criteria for valve replacement are unclear in asymptomatic/minimally symptomatic patients with aortic regurgitation (AR) and normal left ventricular (LV) performance at rest. Moreover, previous studies have not assessed the prognostic capacity of load-adjusted LV performance ("contractility") variables, which may be fundamentally related to clinical state. Therefore, 18 years ago, we set out to test prospectively the hypothesis that objective noninvasive measures of LV size and performance and, specifically, of load-adjusted variables, assessed at rest and during exercise (ex), could predict the development of currently accepted indications for operation for AR.

METHODS AND RESULTS

Clinical variables and measures of LV size, performance, and end-systolic wall stress (ESS) were assessed annually in 104 patients by radionuclide cineangiography at rest and maximal ex and by echocardiography at rest; ESS was derived during ex. During an average 7.3-year follow-up among patients who had not been operated on, 39 of 104 patients either died suddenly (n = 4) or developed operable symptoms only (n = 22) or subnormal LV performance with or without symptoms (n = 13) (progression rate=6.2%/y). By multivariate Cox model analysis, change (delta) in LV ejection fraction (EF) from rest to ex, normalized for deltaESS from rest to ex (deltaLVEF-deltaESS index), was the strongest predictor of progression to any end point or to sudden cardiac death alone. Unadjusted deltaLVEF was almost as efficient. Symptom status modified prediction on the basis of the deltaLVEF-deltaESS index. The population tercile at highest risk by deltaLVEF-deltaESS progressed to end points at a rate of 13.3%/y, and the lowest-risk tercile progressed at 1.8%/y.

CONCLUSIONS

Currently accepted symptom and LV performance indications for valve replacement, as well as sudden cardiac death, can be predicted in asymptomatic/minimally symptomatic patients with AR by load-adjusted deltaLVEF-deltaESS index, which includes data obtained during exercise.

Cardiac function and functional capacity: implications for the failing heart

The exercise capacity of patients with congestive heart failure is determined by factors including the interaction of the right and left ventricles and their respective circulations, lung mechanics, skeletal muscle metabolism, and blood flow. Therapeutic efforts should be directed at all of the units in this complex process rather than the response of an individual system. Multiple therapeutic regimens such as nitrates and angiotensin converting enzyme inhibitors in combination with physical training and other therapies that improve pulmonary function produce optimal results. Using this holistic approach to therapy, the physician may have a beneficial impact on the exercise capacity of patients with congestive heart failure.

Mechanisms for an abnormal radionuclide left ventricular ejection fraction response to exercise in patients with chronic, severe aortic regurgitation

To clarify the mechanisms for an abnormal radionuclide left ventricular (LV) ejection fraction response to exercise in patients with chronic, severe aortic regurgitation (AR), we studied seven control patients and 21 patients with AR. We used exercise radionuclide angiography and catheterization of the right and left sides of the heart to obtain a calculation of LV chamber elastance. The control and AR groups had similar heart rates, systolic blood pressure responses to exercise, and exercise durations. In both patient groups, LV end-diastolic volume did not change with exercise. In contrast to the decrease in LV end-systolic volume (p less than 0.05) and increase in LV ejection fraction (p less than 0.01) in the control group, LV end-systolic volume in the patients with AR increased, resulting in little change in their LV ejection fraction. By stepwise multiple regression analysis, the radionuclide LV ejection fraction at peak exercise in patients with AR was determined by the LV chamber elastance, LV end-systolic volume, and stroke volume at peak exercise (cumulative r = 0.79, p less than 0.02); the change in radionuclide LV ejection fraction from rest to peak exercise was determined by the corresponding change in systemic vascular resistance, regurgitant index, and LV end-diastolic and end-systolic volumes (cumulative r = 0.88, p less than 0.02). These data demonstrate that in patients with AR, the radionuclide LV ejection fraction at peak exercise is principally determined by the cumulative effects of chronic, severe AR on LV systolic chamber performance, and the change in radionuclide LV ejection fraction from rest to peak exercise is principally established by peripheral vascular responses.

Noninvasive determination of left ventricular output and wall stress in volume overload and in myocardial disease by cine magnetic resonance imaging

The current study used cine magnetic resonance imaging to determine the effect of increasing severity of valvular regurgitation on systolic wall stress and to demonstrate that wall stress was disproportionately increased in relation to the severity of regurgitation in patients with myocardial disease. A total of 39 patients with predominantly mitral (n = 22) or aortic (n = 17) regurgitation with (n = 13) and without (n = 26) myocardial disease and 10 normal volunteers were examined with cine magnetic resonance imaging (MRI) at 1.5 T. Left ventricular (LV) cardiac output (CO) and peak systolic (PS) wall stress (WS) and end-systolic (ES) WS were calculated from blood pressure recordings, carotid pulse tracings, and wall thickness (h) and diameter (D) measurements obtained from cine MRI. Patients were classified into three degrees of severity according to their LV regurgitant volume (RV). Myocardial disease was defined by an ejection fraction (EF) of less than 40%. Mean LV EF was 61 +/- 3% in normal volunteers, 64 +/- 3% in patients with regurgitation, and 25 +/- 2% in patients with myocardial disease. LV CO was directly related to RV in patients without myocardial disease, whereas it was disproportionately low in relation to RV in patients with myocardial disease. PS WS was significantly higher in severe mitral and/or aortic regurgitation compared with moderate, mild, and no mitral and/or aortic regurgitation. Compared with the degree of regurgitation, PS WS was disproportionately higher in patients with myocardial disease. Thus LV CO and WS rise progressively with increasing severity of regurgitation. Disproportionately high systolic WS relative to RV indicates the presence of myocardial disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of radionuclide ventriculography in evaluating cardiac function

The role of nuclear cardiology techniques for evaluating cardiac function has become increasingly important among other diagnostic techniques. The current status of radionuclide imaging of left and right ventricular function allows accurate diagnosis of cardiac patients with both coronary and noncoronary disease. The combination of gated first-pass and equilibrium radionuclide ventriculography makes it possible to assess more completely cardiac function than by either technique alone. Of particular interest to most imaging physicians is the current position of exercise ventriculography in the diagnostic setting, especially since this test has undergone new scrutiny in its application to broader patient segments. This technique and issues related to its place in the diagnostic environment are discussed in this review article, with emphasis on relevance to the clinical laboratory.

Effect of digoxin and vasodilators on left ventricular function in aortic regurgitation

In order to assess the relative value of digoxin, nifedipine and hydralazine on left ventricular performance at rest and during exercise, we studied 10 men with moderately severe chronic aortic regurgitation using two-dimensional echocardiography. Digoxin after one month at therapeutic serum levels increased resting ejection fraction as compared to control [0.54 +/- 0.08 (SD) vs 0.47 +/- 0.08, respectively, P less than 0.03]. Ejection fraction decreased during exercise but the difference between digoxin and control was maintained. Stroke volume also was higher on digoxin than control at rest (93 +/- 15 vs 83 +/- 17 ml, P less than 0.02) and the larger stroke volume on digoxin was maintained during exercise. By contrast, stroke volume was reduced by one month of therapy with maximally tolerated nifedipine doses compared to control (74 +/- 8 vs 83 +/- 17 ml, P = 0.03) and this difference was maintained during exercise. Hydralazine in doses up to 225 mg/day for one month produced no significant changes in left ventricular performance compared to control at rest or during exercise. However, compared to digoxin ejection fraction at peak exercise was significantly less on hydralazine (0.39 +/- 0.9 vs 0.52 +/- 10, P less than 0.02). These data suggest that digoxin improved left ventricular performance and may be of benefit in the treatment of patients with chronic aortic regurgitation.

Right ventricular myocardial function after atrial switch operation for transposition of the great arteries

Postoperative right ventricular (RV) myocardial function was evaluated in 6 patients who underwent atrial switching for simple transposition of the great arteries (TGA). The average age at study was 5.5 years. RV function was evaluated at rest and during administration of methoxamine by cardiac catheterization and RV angiography. The data were compared with left ventricular function in a control group, which consisted of 6 patients, 3 with functional murmur and 3 with pulmonary valvar stenosis. During stress, the TGA group showed a significant increase in end-diastolic pressure, minute work index and end-diastolic and end-systolic volume indexes, along with a significant decrease in ejection fraction. The control group also showed an increase in these variables except for ejection fraction during stress, which did not change. The slope of the work-function curve for the TGA group was lower than that for the control group (p = 0.02). The TGA group had a lower slope of the peak systolic pressure-volume relation than the control group (p = 0.005). There was no significant correlation between the slope of the peak systolic pressure-volume relation and age at repair or study. This study shows that RV pump dysfunction observed in postoperative TGA patients may be caused by depressed myocardial function.

Myocardial contractility and left ventricular function in obese patients with essential hypertension

Although the risk of developing congestive heart failure increases in parallel with the degree of obesity, load-dependent indexes of left ventricular function are found to be reduced in patients with morbid obesity only. We used the ratio of end-systolic wall stress to end-systolic volume index, which is load-independent, to assess myocardial contractility in 23 nonobese, 28 mildly obese and 26 moderately obese patients with mild to moderate essential hypertension. Although load-dependent indexes (i.e., ejection fraction, fractional fiber shortening and velocity of circumferential fiber shortening) were similar in the 3 groups, end-systolic wall stress to end-systolic volume index was lower in the moderately obese group (2.63 +/- 0.4, p less than 0.002) and even in the mildly obese group (2.88 +/- 0.8, p less than 0.05) than in the nonobese group (3.27 +/- 0.7). Further, there was a significant inverse relation between end-systolic wall stress to end-systolic volume index and body mass index (r = -0.34, p less than 0.005), diastolic diameter (r = -0.56, p less than 0.001) and left ventricular mass index (r = -0.55, p less than 0.001). Some obese patients have depressed myocardial contractility when compared with lean patients despite well-preserved pump function.

Chronic aortic regurgitation: indications for operation--1988

Timing of operation in a patient with severe aortic regurgitation is a difficult and controversial decision, especially when the patient is asymptomatic or minimally symptomatic. A rational decision can be made when the pathophysiologic features of aortic regurgitation and the natural history of medically treated patients are understood and the benefits and risks associated with aortic valve replacement are known. Proper interpretation of the literature involving echocardiography and nuclear cardiology is essential, as is consideration of the constantly changing surgical techniques and results. Aortic valve replacement should be recommended for those patients with chronic aortic regurgitation who are severely symptomatic (New York Heart Association Functional Class III or IV), in order to ameliorate symptoms and increase longevity. In asymptomatic or minimally symptomatic patients, close continued serial follow-up is necessary in order to detect the onset of resting left ventricular dysfunction and to recommend the optimal timing for surgical intervention.

Intrinsic left ventricular contractility in normal subjects

The influence of autonomic tone on left ventricular (LV) contractility, along with the range of normal values and the effects of exercise on contractile state, were studied in 12 normal volunteers. Serial reproducibility was examined in a subgroup of 6. LV contractility was estimated by the LV peak-systolic pressure to end-systolic volume relation (pressure-volume relation), and the ratio of peak-systolic pressure to end-systolic volume (pressure/volume ratio). The cuff blood pressure and radionuclide ventriculogram were recorded at rest, during exercise and during pharmacologic pressure-afterloading with phenylephrine, before and after vagal and beta-adrenergic "blockade." Both the pressure/volume ratio and ejection fraction increased during the stimulus of exercise (both p less than or equal to 0.008). After blockade, the pressure-volume relations were highly linear (r = 0.95 +/- 0.05 [standard deviation], n = 12), and there was no systematic difference in their slopes induced by blockade. The serial studies of pressure-volume relations showed no significant differences. The results demonstrated that vagal and sympathetic tone were not important in the support of LV contractility in normal subjects at rest, and that the pressure-volume relation and pressure/volume ratio are reproducible between studies. Also, the findings confirmed that both the pressure/volume ratio and the ejection fraction were sensitive to exercise-induced changes in contractility. This demonstration of intrinsic LV contractility in normal subjects, plus the reproducibility of the measurements, supports the feasibility of serial study of LV contractility.

Prognostic implications of left ventricular function during exercise in asymptomatic patients with aortic regurgitation

Few data are available that address the prognostic implications of the response of the left ventricle (LV) to exercise in asymptomatic patients with aortic regurgitation (AR) who have normal resting LV function. Thirty-one such patients were contacted two to seven years after rest and exercise radionuclide ventriculography. Eleven had had significant cardiovascular events. Event-free survival at forty-eight months was 64%. Ten of eleven events occurred in 21 patients with decline in ejection fraction (EF), but the magnitude of decline did not further separate the group with regard to prognosis. Eight events (73% of total events) occurred in the 11 patients (35% of total patients) with an EF during exercise of 0.55 or less. The short and intermediate outlook for asymptomatic patients with AR and normal resting LV function is good regardless of the response of the EF to exercise, but an exercise EF less than or equal to 0.55 does identify a relatively high-risk subset for deterioration beyond twenty-four months.

Relation between left ventricular functional reserve during exercise and resting systolic loading conditions in chronic aortic regurgitation

The relation between systolic loading conditions at rest and left ventricular (LV) functional response to exercise was assessed in 31 patients with aortic regurgitation (AR) (20 asymptomatic, 11 symptomatic) and 10 control subjects. Peak and end-systolic wall stress determined from echocardiography and cuff systolic pressure at rest were used as indirect measures of LV systolic loading and were compared with LV ejection fraction response to handgrip and bicycle exercise by radionuclide ventriculography. Both peak and end-systolic wall stress were significantly higher in both asymptomatic (164 +/- 33 and 90 +/- 25 X 10(3) dynes/cm2) and symptomatic (196 +/- 33 and 134 +/- 17 X 10(3) dynes/cm2) patients with AR than in the control subjects (125 +/- 22 and 61 +/- 14 X 10(3) dynes/cm2 p less than 0.01), and correlated inversely with the changes in LV ejection fraction during handgrip (r = -0.63 and r = -0.73) and bicycle (r = -0.68 and r = 0.87) exercise. In patients with AR, resting systolic loading conditions closely reflect LV functional reserve during exercise.

Radionuclide angiographic evaluation of left ventricular performance at rest and during exercise in patients with aortic regurgitation

Radionuclide angiographic evaluation of LV performance at rest and during exercise in patients with AR have shown that an abnormal EF response to exercise may be observed in asymptomatic patients with normal resting LV function. The EF response to exercise has been correlated with a number of clinical and exercise measurements; important among these are the slope of the systolic pressure-to-end-systolic volume, end-systolic volume, cardiac index, pulmonary capillary wedge pressure, and wall stress. The changes in the regurgitant fraction, EF, and LV volume have shown considerable individual variability; they have also allowed a better understanding of the circulatory responses during exercise. Radionuclide angiography provides a reliable and reproducible method of measuring the rest LVEF that is important in the timing and the outcome of valve replacement. The value of the EF response to exercise in patient management is not yet clear; it is possible that other radionuclide-derived measurements at rest or during exercise, such as the systolic pressure-to-end-systolic volume relationship, and the end-systolic volume may provide complementary information to that provided by the EF.

Cardiovascular response to dynamic exercise in patients with chronic symptomatic mild-to-moderate and severe aortic regurgitation

Fifteen patients with symptomatic mild-to-moderate and severe chronic aortic regurgitation (AR) performed supine bicycle exercise while measurements of rest and exercise hemodynamics and left ventricular function were obtained. A continuous Doppler method was used to determine the change in distribution of total left ventricular stroke volume between forward stroke volume and regurgitant volume (RgV) with exercise. The pulmonary arterial wedge pressure (PAWP) was lower in the mild-to-moderate AR group than in the severe AR group at rest (8 +/- 1.2 vs 19 +/- 3.6 mm Hg, p = 0.01) and during exercise (15 +/- 3.9 vs 30 +/- 4.3 mm Hg, p = .02). In all patients there were increases in heart rate (78 +/- 4 to 96 +/- 5 beats/min, p less than .001), forward stroke volume (41 +/- 2 to 46 +/- 2 ml/m2), and the cardiac index (3.1 +/- 0.2 to 4.4 +/- 0.3 liters/min-m2, p less than .001), despite a fall in total left ventricular stroke volume index from 84 +/- 5 to 76 +/- 5 ml/m2 (p = .03). The systemic vascular resistance (SVR) decreased with exercise from 1277 +/- 72 to 1031 +/- 64 dynes-sec/cm5 (p less than .001), and the RgV and regurgitant fraction (RgF) both decreased with exercise from 43 +/- 5 ml/m2 to 30 +/- 4 ml/m2 (p = .002) and 0.50 +/- 0.03 to 0.37 +/- 0.03 (p less than .001), respectively. Left ventricular ejection fraction increased on exercise from 0.51 +/- 0.03 to 0.55 +/- 0.03 (p = .02) for the group, but it either decreased or failed to increase by at least 0.05 in seven of 13 patients. The change in ejection fraction on exercise was directly related to the change in SVR (r = .80, p less than .001). We conclude that: in patients with mild-to-moderate AR, the PAWP is generally normal at rest and exercise, in most of those with severe AR, the PAWP is elevated at rest and increases significantly with exercise, which is the likely mechanism for dyspnea on exertion in these patients, the cardiac index in both groups is normal at rest and increases on exercise, the increase in cardiac output results from both an increased heart rate and forward stroke volume, the increase in forward stroke volume results from reductions of RgV and RgF, the RgV and RgF are decreased due to a decreased SVR, and the ejection fraction response to exercise is variable and correlates best with changes in SVR with exercise.

Left ventricular pressure/volume relationship in aortic regurgitation

In this study we examined the left ventricular pressure/volume relationship in 39 patients with moderate or severe aortic regurgitation (AR) and 15 normal subjects. The patients with AR were divided into two groups; patients with normal resting ejection fraction (EF greater than or equal to 50%, group I, n = 21) and patients with abnormal EF (group II, n = 18). The patients in group I were younger (p less than 0.005), exercised to a higher workload, and had better exercise tolerance than patients in group II (p less than 0.01). The patients' exercise heart rate and blood pressure were not significantly different between the two groups. During exercise tests nine patients in group I and seven patients in group II had normal EF response (greater than or equal to 5% increase) (p = NS). The peak systolic blood pressure to end-systolic volume index ratio (SBP/ESVI) was higher in normal subjects than in patients in groups I and II, at rest it was (4.3 +/- 1.0 vs 2.6 +/- 1.2 vs 1.6 +/- 0.8, respectively, p less than 0.0001) and during exercise it was (7.6 +/- 1.8 vs 4.2 +/- 1.4 vs 2.6 +/- 1.3, respectively, p less than 0.0001). The resting SBP/ESVI ratio was below the lower normal limit in 12 patients (57%) in group I and in 16 patients (89%) in group II. Also, the exercise SBP/ESVI ratio was below the lower normal limit in 17 patients (81%) in group I and all of the patients (100%) in group II. Multivariate discriminant analysis identified the change in SBP/ESVI (F = 34.8) and resting end-diastolic volume (F = 6.7) as independent predictors of the EF response to exercise. Thus, most patients with AR, including those with normal resting EF or normal EF response to exercise, have abnormal SBP/ESVI at rest or during exercise.

Comparison of effects of isometric and supine bicycle exercise on left ventricular performance in patients with aortic regurgitation and normal ejection fraction at rest

The effects of handgrip and supine bicycle exercise on hemodynamics and left ventricular (LV) performance were compared in 25 patients with moderate to severe aortic regurgitation (AR) and normal LV ejection fraction at rest (greater than or equal to 50%) and in 10 control subjects. In both groups, heart rate, systolic blood pressure, rate-pressure product, and LV output were higher during supine bicycle exercise. Compared with the controls, in patients with AR, stroke volume was unchanged during supine bicycle exercise. LV end-diastolic volume increased during handgrip exercise but was unchanged during supine bicycle exercise. LV end-systolic volume increased and ejection fraction decreased during both forms of exercise. Of 25 patients with AR, 15 (60%) during handgrip exercise and 19 (76%) during supine bicycle exercise had an abnormal ejection fraction response (p less than 0.05). In patients with moderate to severe AR and normal LV ejection fraction at rest, both handgrip and supine bicycle exercise induced LV dysfunction. An abnormal LV ejection fraction response occurred more often with supine bicycle exercise. Handgrip exercise may be a useful alternative method for detecting LV dysfunction in patients with AR in whom adequate bicycle exercise cannot be accomplished.