Effects of sustained isometric handgrip on praecordial accelerocardiogram in normal subjects and in patients with heart disease.

The effects of isometric exercise on the maximum amplitude of the praecordial accelerocardiogram (as represented by the DE deflection) have been compared in 6 normal subjects (group 1), 12 patients with aortic stenosis (group 2), and 16 patients with myocardial disease (group 3). Whereas the tachycardia and pressor effects of isometric exercise were identical in all three groups, the normal subjects showed a significant decrease in DE during handgrip of 10 +/- 4 per cent (P less than 0.05) as compared with the insignificant increases of 8.5 +/- 6 per cent (P greater than 0.5), and 4 +/- 3.5 per cent (P greater 0.3) observed in the patients in groups 2 and 3. This response in the normal subjects differed significantly from the responses observed in the patients in groups 2 (P less than 0.02) and 3 (P less than 0.01). Of the patients in each of groups 2 and 3, 50 per cent responded abnormally to handgrip in that they showed a significant increase in DE. In the patients with aortic stenosis this subgroup of patients differed from the remainder in that they had a higher resting cardiac index (P less than 0.05). In the patients with myocardial disease this subgroup was characterized by a significantly lower resting left ventricular end-diastolic pressure (P less than 0.02). It seems, therefore, that those patients who increase DE in response to handgrip tend to have better left ventricular function at rest than those who do not. We suggest that this may be because of increased beta adrenergic activity at rest and during isometric exercise in the subgroup who respond to handgrip with an increase in DE.     

Correlation between praecordial accelerocardiogram and left ventricular pressure.

The praecordial accelerocardiogram possesses important practical advantages over more familiar techniques of recording praecordial pulsations. We have compared the amplitude of the P wave of the praecordial accelerocardiogram in 6 normal subjects (group 1) and 21 patients with heart disease (group 2) at rest and after 3 minutes of isometric handgrip at 30 per cent maximum voluntary contraction. At rest in group 2 there was a significant linear correlation between the amplitude of the P wave of the accelerocardiogram, relative to the maximum systolic amplitude (P/DE), and the left ventricular end-diastolic pressure (P less than 0-01). However, comparison of the data for P/DE showed that the mean value (+/-SEM) of 29+/-5 per cent in group 1 was not significantly different from the mean value of 37+/-4 per cent in group 2 (P g .reater than 0-30). During handgrip the mean amplitude of the P wave did not increase significantly in group 1 (P greater than 0-20) but increased significantly in group 2 (P less than 0-02). In group 2 there was a significant linear correlation between the percentage increase in the amplitude of the P wave of the accelerocardiogram during handgrip and the percentage increase in the left ventricular end-diastolic pressure (P less than 0-01).     

Correlation between praecordial accelerocardiogram and left ventricular pressure.

The praecordial accelerocardiogram possesses important practical advantages over more familiar techniques of recording praecordial pulsations. We have compared the amplitude of the P wave of the praecordial accelerocardiogram in 6 normal subjects (group 1) and 21 patients with heart disease (group 2) at rest and after 3 minutes of isometric handgrip at 30 per cent maximum voluntary contraction. At rest in group 2 there was a significant linear correlation between the amplitude of the P wave of the accelerocardiogram, relative to the maximum systolic amplitude (P/DE), and the left ventricular end-diastolic pressure (P less than 0-01). However, comparison of the data for P/DE showed that the mean value (+/-SEM) of 29+/-5 per cent in group 1 was not significantly different from the mean value of 37+/-4 per cent in group 2 (P g .reater than 0-30). During handgrip the mean amplitude of the P wave did not increase significantly in group 1 (P greater than 0-20) but increased significantly in group 2 (P less than 0-02). In group 2 there was a significant linear correlation between the percentage increase in the amplitude of the P wave of the accelerocardiogram during handgrip and the percentage increase in the left ventricular end-diastolic pressure (P less than 0-01).     

Influence of isometric exercise on left ventricular diastolic function in the normal subjects and in patients with hypertension and coronary heart disease]

To evaluate the influence of isometric exercise on left ventricular (LV) diastolic function, transmittal flow velocity was measured by pulsed Doppler echocardiography before and after handgrip in 15 normal subjects and the patients with hypertension as well as 18 patients with coronary heart disease (CHD). Statistically significant differences in peak velocity of early rapid filling (Ev), the ratios of peak early to late diastolic velocity (Ev/Av) and early to late velocity-time integral (Ei/Ai) between normal subjects and both the patients with hypertension and CHD were noted at rest. After isometric exercise, significant increase in Av (0.70 +/- 0.13 vs 0.76 +/- 0.14, P less than 0.01) and Ai/total VTi (0.35 +/- 0.07 vs 0.42 +/- 0.08, P less than 0.05) were showed in the hypertension group. In CHD, multiple Doppler parameters changed after isometric exercise with increase in Av (0.70 +/- 0.16 vs 0.85 +/- 0.18, P less than 0.01) and Ai/total VTi (0.36 +/- 0.08 vs 0.42 +/- 0.08, P less than 0.01) as well as decrease in Ev/Av (0.95 +/- 0.22 vs 0.82 +/- 0.15, P less than 0.05) and Ei/Ai (1.64 +/- 0.51 vs 1.35 +/- 0.34, P less than 0.05). However, there was no significant difference in any Doppler indices of LV diastolic function in the present normal subjects after isometric exercise. Thus, isometric exercise further enhanced late LV diastolic filling in the patients with impaired LV diastolic function in resting states greater than normal subjects, and myocardial ischemia induced by handgrip may play partial role in more changes in Doppler indices of LV diastolic function in CHD than the patients with hypertension.     

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

We studied the relationship between myocardial contractile state and left ventricular functional response to exercise in 14 asymptomatic patients with isolated moderate-to-severe aortic regurgitation and six control subjects. The slope of the systolic blood pressure-left ventricular end-systolic volume (pressure-volume) relationship determined by radionuclide ventriculography during angiotensin infusion was used as an indirect measure of myocardial contractility and was compared with left ventricular ejection fraction at rest and during both isometric handgrip and dynamic bicycle exercise. The slope of the pressure-volume relationship was significantly lower in patients with aortic regurgitation than in the control subjects (1.75 +/- 0.57 vs 2.78 +/- 0.42, p less than 0.01). The slope correlated exponentially with resting ejection fraction and was linearly related to changes in left ventricular ejection fraction during both handgrip and bicycle exercise. In patients with aortic regurgitation, resting ejection fraction may overestimate myocardial function. The slope of the pressure-volume relationship measured during afterload stress and left ventricular ejection fraction response to exercise intervention more reliably reflect the degree of left ventricular dysfunction.     

Effect of isometric hand-grip exercise on left ventricular diastolic filling in patients with effort angina: a pulsed Doppler echocardiographic study

To detect myocardial ischemia and to estimate cardiac reserve in patients with effort angina pectoris without history of myocardial infarction, left ventricular diastolic filling was measured using Doppler echocardiography during isometric handgrip exercise. Nineteen patients with effort angina pectoris undergoing coronary angiography and 16 normal subjects were studied. The angina patients were categorized in two groups: 12 with single vessel disease (SVD) and seven with multiple vessel disease (MVD). Fifty percent maximum voluntary contraction isometric handgrip exercise was performed for two minutes. 1. The resting A/R in the angina group was significantly greater than that of the normal subjects (SVD: 1.20 +/- 0.24, MVD: 1.21 +/- 0.27, normal 0.85 +/- 0.10) (p less than 0.001). However, the values of many cases in these three groups overlapped. 2. In SVD, the A/R increased significantly during isometric handgrip exercise (1.20 +/- 0.24 to 1.96 +/- 0.66: p less than 0.001). The delta A/R (0.76 +/- 0.15) was significantly greater than that of patients in other groups (MVD: 0.10 +/- 0.13, normal: 0.09 +/- 0.01) (p less than 0.001). Consequently, the A/R after exercise clearly distinguished the SVD from the normal subjects. 3. In MVD, the A/R did not change significantly during exercise (1.21 +/- 0.27 to 1.31 +/- 0.41), and there were no significant differences in delta A/R as compared to the normal subjects (p less than 0.01). The A/R decreased during exercise in three of the seven patients, and this was markedly different from that of the normal subjects. These findings suggest that assessment of changes in left ventricular diastolic filling during isometric handgrip exercise is useful in detecting myocardial ischemia and in estimating cardiac reserve in patients with effort angina pectoris.     

Beneficial effects of nitroglycerin on abnormal ventricular wall motion at rest and during exercise in patient with previous myocardial infarction.

The effects of sublingually administered nitroglycerin on segmental left ventricular wall motion determined by videotracking and radiographic left heart size were evaluated at rest and during submaximal hand grip exercise in 10 patients with previous transmural myocardial infarction. After nitroglycerin, diastolic left heart size decreased in the resting state from an average of 49.5 +/- 5.7 (standard deviation) to 47.9 +/- 5.6 mm/m2 body surface area (P less than 0.01) and during handgrip exercise from a mean of 50.7 +/- 590 to 49.1 +/- 4.7 mm/m2 (P less than 0.05). In the resting state, the average maximal velocity of shortening in segments with normal wall motion increased after nitroglycerin from 18.1 +/- 3.0 to 23.5 +/- 5.5 mm/sec (P less than 0.01), whereas during handgrip exercise alone, the velocity of shortening averaged 25.6 +/- 6.9 mm/sec and increased further after nitroglycerin to 30.1 +/- 10.6 mm/sec (P less than 0.05). The effects of nitroglycerin on the average extent of shortening in normal segments were similar. In all 10 patients, there was a decrease in the number of segments with abnormal wall motion. The number of sites with dyssynergy decreased after nitroglycerin from 24 to 15 in the resting state and from 40 to 22 when nitroglycerin was administered before handgrip exercise. Sublingually administered nitroglycerin appears to decrease left heart size, increase the velocity and extent of shortening in normal left ventricular segments and often reduce the extent of left ventricular wall motion abnormalities at rest and during isometric exercise in patients with previous transmural myocardial infarction.     

Systolic time intervals in progressive muscular dystrophy.

Indirect systolic time intervals corrected for heart rate were measured at rest, during, and immediately after the isometric handgrip exercise in 70 patients with progressive muscular dystrophy, and these were compared with the values of normal subjects. Those with dystrophy included 47 patients with Duchenne type, 19 with limb girdle type and 4 with facioscapulohumeral type, and each type was subdivided into 2 groups by the severity of the skeletal muscle involvement: 1) mild group, included patients who were still able to walk, 2) severe group, included those who were restricted to wheel chair or confined to bed. Over a half of the patients of the severe Duchenne type group had a longer pre-ejection period (PEP), shorter left ventricular ejection time (LVET), and larger PEP/LVET ratio at rest than the normal group. Increased PEP/LVET ratio during and after isometric handgrip exercise was observed in the severe group of Duchenne type. The patients with limb girdle type, and facioscapulohumeral type showed no significant difference in values of the systolic time intervals at rest and during handgrip exercise compared with the normal subjects. The measurements of resting and exercise systolic time intervals may be useful for clinical recognition of latent left ventricular functional impairement in subjects with progressive muscular dystrophy.     

Favorable effects of orally administered digoxin on left heart size and ventricular wall motion in patients with previous myocardial infarction.

The effects of maintenance oral digoxin therapy on segmental left ventricular wall motion (wall motion videotracking) and left heart size (radiographic left heart dimension) were evaluated in 14 patients with a prior myocardial infarction but without clinical signs or symptoms of congestive heart failure. The left heart dimension decreased in all six patients with cardiomegaly from an average of 55.0 +/- 1.6 (standard deviation) to 52.2 +/- 2.7 mm/m2 body surface area (P less than 0.01) during digoxin therapy. However, there was no significant change in the eight patients with normal heart size. In the resting state, the average extent of shortening in normal segments increased significantly from 3.1 +/- 0.8 to 4.2 +/- 1.2 mm during digoxin therapy. During submaximal handgrip exercise, the extent of shortening averaged 4.0 +/- 1.3 mm and increased further with digoxin therapy to 5.1 +/- 2.1 mm. The effects of digoxin therapy on the maximal velocity of shortening in normal segments at rest and during handgrip exercise were similar. In all 14 patients, there was a decrease in the number of segments with abnormal wall motion at rest or with handgrip exercise during digoxin therapy. With therapy, the number of abnormal sites decreased from 52 to 35 in the resting state and from 84 to 49 during handgrip exercise. Thus, in patients 6 or more months after transmural myocardial infarction, orally administered digoxin decreases cardiomegaly, increases the extent and maximal velocity of shortening in normal left ventricular segments and often reduces the extent of abnormal wall motion at rest or during isometric exercise.     

Blood pressure at rest and during maximal dynamic and isometric exercise as predictors of systemic hypertension

This study sought to verify evidence that transient high blood pressure (BP) at rest and during dynamic and isometric exercise is often predictive of later hypertension. In addition these 3 predictors were compared. One hundred office patients (all men) with BPs less than 140/90 mm Hg, ages 28 to 79 years, who had little or no heart disease and were not taking medication, had BPs taken at rest and during treadmill and handgrip dynamometer. Within 14 years, 16 subjects developed hypertension and 84 remained normotensive. Multivariate statistical comparisons for systolic and diastolic BPs and their interactions were used to discriminate between later hypertensive and normotensive subjects. The best single predictor was resting diastolic BP, classifying 88% of hypertensive and 69% of normotensive subjects correctly, followed closely by handgrip and treadmill diastolic BP and resting, treadmill and handgrip systolic BP. The best prediction was by the interaction between resting diastolic BP X handgrip diastolic BP; this classified 88% of hypertensive and 80% of normotensive subjects correctly. Of the few known precursors of hypertension, high BP at rest and during dynamic and isometric stress provides a means of alerting to careful follow-up and early treatment.     

Static versus dynamic exercise: effects on Doppler echocardiographic indices of left ventricular performance.

In order to compare the effects of static exercise with those of dynamic exercise on the Doppler echocardiographic measurements of ascending aortic blood flow velocity and acceleration, Doppler echocardiography was performed with sustained handgrip exercise and with supine bicycle exercise in 12 normal subjects, 12 patients with coronary artery disease, and 7 patients with heart failure. In normal subjects: peak velocity decreased by 16 +/- 11% with handgrip from the resting value and increased by 49 +/- 19% with bicycle exercise (p less than 0.01); mean acceleration decreased by 6 +/- 30% with handgrip and increased by 162 +/- 83% with bicycle exercise (p less than 0.01). In patients with coronary artery disease: peak velocity declined by 9 +/- 14% with handgrip and increased by 19 +/- 18% with bicycle exercise (p less than 0.01); mean acceleration increased by 13 +/- 27% with handgrip and by 41 +/- 33% with bicycle exercise (NS). In patients with congestive heart failure: peak velocity decreased by 19 +/- 13% with handgrip and increased by 5 +/- 17% with bicycle exercise (p less than 0.01); mean acceleration decreased by 12 +/- 23% with handgrip and by 4 +/- 37% with bicycle exercise. A marked increase in afterload stress induced by static exercise presumably offsets the moderately increased contractility and accounts for the decline of peak velocity and mean acceleration with static exercise both in normals and cardiac patients. In contrast, marked increase in contractile state along with little change in afterload with dynamic exercise results in markedly increased peak velocity and mean acceleration in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of postural changes and isometric exercise on Doppler-derived measurements of diastolic function in normal subjects

To determine if simple maneuvers that occur in daily life, such as changes in body position and isometric handgrip exercise, affect Doppler-derived measurements of diastolic function, we studied 22 normal male subjects in the supine position at rest and during several postural manipulations and during handgrip exercise. Comparison of values obtained in the 80 degrees upright tilt position with those obtained in the standard supine position revealed significant decreases in early diastolic flow velocity (peak E) (-25 +/- 3 percent; p less than 0.001), late diastolic flow velocity (peak A) (-9 +/- 3 percent; p less than 0.01), and the ratio of early to late flow velocities (E/A ratio) (-17 +/- 4 percent; significant increases in deceleration time (+55 +/- 10 percent; p less than 0.001) and isovolumic relaxation time (+38 +/- 4 percent; p less than 0.001). Comparison of values obtained with supine isometric exercise with those obtained during the preceding supine resting state revealed significant decreases in peak E (-12 +/- 3 percent; p less than 0.001) and the E/A ratio (-21 +/- 4 percent; p less than 0.001) and significant increases in peak A (+15 +/- 4 percent; p less than 0.001) and isovolumic relaxation time (+16 +/- 3 percent; p less than 0.001). The response of Doppler-derived measurements of diastolic function to postural changes and isometric exercise is complex and multifactorial. Interpretation of these measurements must take into account changes in loading conditions.     

Regional left ventricular mechanical function during isometric exercise in patients with coronary artery disease: correlation with regional coronary blood flow changes

The effects of isometric exercise on regional left ventricular mechanical function and regional coronary blood flow were evaluated in 17 patients with significant proximal stenosis of the left anterior descending coronary artery and 10 patients with normal coronary arteriograms. All patients had normal myocardial contractility in the basal condition. All performed isometric handgrip exercise at 50% of the maximal voluntary contraction for 3 min during two-dimensional echocardiographic monitoring and hemodynamic evaluation of great cardiac vein flow by thermodilution technique. During isometric exercise, 7 of the 17 patients with left anterior descending coronary stenosis developed asynergy in the anterior territory (anterior or septal segment, or both) (group I); the remaining 10 showed normal myocardial contraction during the test (group II). The 10 normal subjects manifested no regional asynergy during the test (control group). The increase in great cardiac vein flow at peak isometric exercise was significantly smaller (p less than 0.01) in group I (+15 +/- 8%) than that in group II (+98 +/- 48%) and the control group (+64 +/- 22%). Anterior coronary vascular resistance decreased in group II (-32 +/- 13%) and in the control group (-25 +/- 8%) but increased in group I (+6 +/- 8%, p less than 0.01 versus group II and control group). These data demonstrate that handgrip-induced myocardial asynergy is associated, in our study patients, with an abnormal response of the regional coronary circulation. The increase in coronary vascular resistance in group I patients with asynergy demonstrates that functional mechanisms play a dominant role in left ventricular mechanical dysfunction induced by isometric exercise.     

Effect of coronary artery bypass grafting on left ventricular response to isometric exercise

The left ventricular (LV) response to isometric exercise was evaluated in 20 patients who performed handgrip exercise tests before and 3 months after coronary artery bypass grafting. Preoperative LV ejection fraction (EF) decreased during the handgrip test from 0.57 +/- 0.08 to 0.49 +/- 0.09 (p less than 0.001); the ratio between the LV peak systolic pressure (PSP) and end-systolic volume index (ESVI) did not change. In 12 patients with patent grafts, the LVEF after operation did not change (0.54 +/- 0.06 at rest and 0.56 +/- 0.06 during handgrip exercise) and PSP/ESVI ratio increased from 4.5 +/- 1.5 to 5.6 +/- 2.1 mm Hg/ml X m-2 (p less than 0.001) during exercise. In 8 patients with occluded grafts, the LVEF after operation decreased from 0.56 +/- 0.10 to 0.48 +/- 0.06 (p less than 0.02), whereas PSP/ESVI did not change during handgrip exercise. Thus, the LV response to isometric handgrip exercise appears to improve after coronary artery bypass grafting in patients with patent grafts, but not in patients with 1 or more occluded grafts.     

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.     

Effects of training on systolic time intervals at rest and during isometric exercise in men and women 61 to 64 years old

To determine whether regular exercise improves left ventricular (LV) contractile function in persons 60 years and older, systolic time intervals (STIs) were measured in 10 healthy men and women (mean age 62 +/- 1 year [+/- standard deviation]) before and after 6 months of intense endurance training. STIs, systolic and diastolic blood pressure (BP) and heart rate (HR) were determined at rest and in response to isometric handgrip exercise. Systolic BP, diastolic BP and HR increased acutely from rest in response to handgrip (p less than 0.002). The indexes of total electromechanical systole and LV ejection time (ET) index increased (p less than 0.01), preejection period (PEP) index increased (p less than 0.05) or remained unchanged and PEP/LVET did not change from values at rest in response to handgrip. Training resulted in an 18% increase in maximal oxygen uptake (p less than 0.01). After training, systolic and diastolic BP were reduced at rest (p less than 0.002) and, along with HR, were lower in response to handgrip (p less than 0.002). However, training did not alter STIs at rest or during handgrip. These findings indicate that healthy persons in their 60s have a normal LV response to isometric exercise. Prolonged, intense endurance training does not alter LV contractile function at rest or in response to isometric exercise. However, training can significantly reduce BP at rest, and markedly lower the HR-systolic BP product attained during acute isometric stress, even in normotensive older subjects.     

Response of upper limb blood flow to handgrip exercise after Blalock-Taussig operation (for tetralogy of Fallot) or subclavian flap operation (for aortic isthmic coarctation)

To evaluate the effects of long-term reductions in perfusion pressure on blood flow responses to increased functional demand, 5 patients (aged 12 to 26 years) without normal aortic to subclavian artery blood flow to 1 arm as a result of surgery to treat congenital heart disease were studied. Five age- and sex-matched healthy (control) subjects were also studied. In the patients, forearm blood flow was not different in the surgical and normal arms at rest (3.6 +/- 0.6 vs 4.0 +/- 0.7 ml/min/100 ml, respectively, mean +/- standard error, difference not significant) despite lower systolic blood pressure in the surgical arm (87 +/- 2 vs 115 +/- 2 mm Hg, p less than 0.05). The increases in heart rate, systolic blood pressure, forearm electromyographic activity (index of muscle fatigue) and postexercise forearm blood flow (index of muscle oxygen deficit) were not different in response to 2.5 minutes of submaximal rhythmic handgrip exercise (50% of maximal force) performed with the surgical versus the normal arms. Peak forearm blood flow elicited by combined ischemia and maximal isometric handgrip exercise was not significantly different in surgical and normal arms in the group as a whole (39 +/- 4 vs 43 +/- 3 ml/min/100 ml, difference not significant), although some bilateral deficit (20 to 38%) was observed in 2 patients. No bilateral differences were observed in the control subjects under any condition. The finding of normal physiologic adjustments to submaximal rhythmic handgrip exercise with the surgical arm suggests that oxygen delivery during exercise was adequate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the cardiac output and stroke volume response to upright exercise in children with valvular and subvalvular aortic stenosis

Cardiac output and stroke volume were evaluated in 17 children (mean age 11.5 +/- 3 years) with discrete, membranous subvalvular (Group I, n = 7) and valvular (Group II, n = 10) aortic stenosis during submaximal and maximal (greater than 75% predicted maximal oxygen consumption) upright cycle ergometry. Patients with valvular aortic stenosis were further subdivided on the basis of their aortic valve gradient at rest determined by cardiac catheterization (Group IIA, gradient less than 40 mm Hg; Group IIB, gradient greater than or equal to 40 mm Hg). These patients were matched with 17 control subjects on the basis of age, sex, height and intensity of exercise during maximal exertion. Cardiac and stroke indexes were determined by the acetylene rebreathing method at each exercise level. Stroke volume index in Group I was significantly greater at rest when compared with that in control subjects (69 +/- 13 versus 53 +/- 11 ml/m2, alpha = 0.01, p less than 0.05) and that in patients in Group II (69 +/- 13 versus 47 +/- 12 ml/m2, alpha = 0.01, p less than 0.05). Patients with subvalvular aortic stenosis were unable to increase their stroke volume index from rest to submaximal exercise and also decreased their stroke volume index at maximal exercise levels. In contrast, patients with mild valvular aortic stenosis (Group IIA) displayed a normal exercise response. Patients with severe valvular aortic stenosis (Group IIB) had a blunted stroke volume response at rest and at each level of exercise, as well as signs of myocardial ischemia (ST segment depression) during maximal exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Effects of captopril on forearm oxygen consumption during dynamic handgrip exercise in patients with congestive heart failure

The maximal exercise capacity of patients with congestive heart failure (CHF) is frequently decreased because of decreased skeletal muscle oxygen utilization. In this study we examined whether forearm oxygen utilization is decreased during dynamic handgrip exercise in patients with CHF and whether captopril improves forearm oxygen utilization. They were divided into 3 groups according to the level of plasma renin activity (PRA) and New York Heart Association functional classification (NYHA): Group 1 consisted of 7 normal (control) subjects (PRA: 0.5 +/- 0.2 ng/ml/h, NYHA: 0); Group 2, 7 patients with severe CHF (PRA: 11.3 +/- 3.9 ng/ml/h, NYHA: 3.6 +/- 0.3); Group 3, 4 patients with mild CHF (PRA: 2.4 +/- 0.2 ng/ml/h, NYHA: 2 +/- 0). Forearm blood flow was measured by a strain gauge plethysmograph at rest and during dynamic handgrip exercise. Regional arterial venous oxygen content was measured and forearm oxygen consumption was calculated by the Fick principle. Forearm blood flow was less (p less than 0.05) at rest and during exercise in patients with severe CHF than in control subjects; this was compensated for by increased oxygen extraction, thus maintaining forearm oxygen consumption at a normal level at rest and during submaximal exercise. During maximal exercise, oxygen extraction was not different between normal control subjects and patients with severe CHF, thus forearm oxygen consumption was significantly less (p less than 0.01) in patients with severe CHF than in control subjects. In patients with mild CHF, forearm blood flow, oxygen extraction and oxygen consumption were not different from those in normal control subjects. Captopril (25 mg orally) did not alter forearm hemodynamics at rest and during exercise in control subjects and patients with mild CHF. In patients with severe CHF, captopril lowered systolic and mean blood pressure (p less than 0.05). Captopril increased forearm oxygen extraction (p less than 0.05) and tended to increase blood flow and thus increased oxygen consumption (p less than 0.01) during maximal exercise. Our data indicate that oxygen utilization was impaired in patients with severe CHF and that captopril improved forearm oxygen utilization during maximal handgrip exercise in patients with severe CHF.