Echocardiographic evaluation of left ventricular reserve in normal children during supine bicycle exercise

To evaluate left ventricular reserve in normal children 127 healthy boys and girls (71 males, 56 females) were investigated with echocardiography during supine bicycle exercise at levels of 6, 9, 12 and 15 kpm/min/kg body weight. Left ventricular function parameters were obtained from the M-mode echocardiogram, electrocardiogram and phonocardiogram. The children were separated into three groups according to body surface area: group I less than 1.1 m2, group II 1.1-1.4 m2, and group III greater than 1.4 m2. Fractional shortening (FS) of the left ventricle rose during exercise from 37 +/- 4 to 46 +/- 4% with no significant differences between the three groups. Velocity of circumferential fiber shortening (Vcf) in group I augmented from 1.3 to 2.25 circ./sec, in group II from 1.29 to 2.60 circ./sec, and in group III from 1.17 to 2.74 circ./sec (P = 0.01). In the recovery period heart rate (HR) and blood pressure normalized earlier than did fractional shortening and velocity of circumferential fiber shortening. This could be expressed best by the ratios FS/HR and Vcf/HR. There were no significant differences between sexes, although there was a tendency to higher blood pressure and heart rate, a greater increase in velocity of circumferential fiber shortening and a smaller increase in fractional shortening in girls. These data indicate that girls increased cardiac output during exercise more by increasing their heart rate than did boys.     

Indices of left ventricular systolic function derived by computer analysis of digitised M-mode echocardiograms

In order to determine the value of computer-assisted analysis of echocardiograms we digitised 980 M-mode studies in normal subjects and patients with pressure and volume overload and heart muscle disease to derive left ventricular dimensions (D), peak systolic rate of change of dimension, normalized for instantaneous dimension (dD/dt/D), mean velocity of circumferential fiber shortening (mean Vcf) and percentage fractional shortening (%FS). The systolic phase indices which, in these patients averaged greater than normal in those with aortic stenosis and hypertrophic cardiomyopathy and lower than normal in those with aortic regurgitation, mitral stenosis and dilated cardiomyopathy, were closely related to each other in all categories of patients. Measurement of % FS appears to describe left ventricular function as well as the more complex indices (mean Vcf, peak dD/dt/D).     

Echocardiographic assessment of left ventricular function in aortic valve disease.

Echocardiography was used to study left ventricular size and contraction in 128 patients with isolated aortic valve disease -45 patients with aortic stenosis, 25 with mixed aortic valve disease and 58 with aortic regurgitation. Left ventricular measurements included the end-diastolic internal dimension (LVIDd), mural thickness (PWTd), an index of circumferential myocardial contraction-fractional shortening (FS=[(LVIDd-LVIDs)/LVIDd] X 100)--and stroke volume (LVSV). In the absence of left ventricular failure, measurements in aortic stenosis were characteristic of pressure overload with normal LVIDd and FS and an increase in PWTd related to the severity of stenosis; in aortic regurgitation, there was volume overload with increases in LVIDd and PWTd which were related to the severity of regurgitation, while FS was slightly reduced. In mixed aortic valve disease there was evidence of both pressure and volume overload. When left ventricular failure was associated with aortic stenosis, mixed aortic valve disease and chronic aortic regurgitation, FS was usually reduced. By contrast, in a recent patient with acute severe aortic regurgitation, FS was normal despite left ventricular failure, suggesting pump rather than myocardial failure.     

Dynamic exercise echocardiography of the left ventricle in physically trained children compared to untrained healthy children

To evaluate the effect of physical training on left ventricular function, we investigated 52 children, aged 7 to 14 years, who had trained for endurance sports over a period of at least 1 year. The children (24 boys and 28 girls) were investigated echocardiographically during supine exercise on a bicycle at increasing work loads of 6, 9, 12 and 15 kpm/min/kg body weight. The parameters of left ventricular function (specifically fractional shortening and the velocity of circumferential fiber shortening; both these parameters corrected for heart rate) were evaluated before, during and after the test. The values obtained were compared to those in untrained children investigated in a previous study. Fractional shortening in trained children rose from 37 +/- 5% to 54 +/- 5%, and in untrained children from 37 +/- 4% to 46 +/- 4%. The velocity of fiber shortening in trained children rose from 1.27 to 3.15 circ/sec while in untrained children it increased from 1.25 to 2.53 circ/sec. Left ventricular contraction, therefore was significantly greater in trained than in untrained children during exercise. While untrained children increased their cardiac output in the first minutes of exercise mainly by elevating their heart rate, trained children increased simultaneously the stroke volume. There were no significant differences between boys and girls, or between stages of maturity. Thus, physical training causes quick adaptations of left ventricular function to exercise in children of all ages.     

Changes in echocardiographic left ventricular minor axis dimensions during exercise in patients with aortic stenosis.

Twelve patients with aortic stenosis (gradient 62 (25) mm Hg), and six normal subjects were examined using M mode echocardiography before and during submaximal bicycle exercise. Normal subjects showed a progressive fall in the end systolic minor axis dimension of the left ventricle and a rise in end diastolic dimension, giving an increase in stroke dimension and shortening fraction of 45% and 37% respectively at peak exercise. Patients with aortic stenosis showed no consistent alteration in either end systolic or end diastolic dimension, and consequently stroke dimension was unchanged during exercise. None of the patients with an abnormal exercise response had evidence of left ventricular failure at rest, and all but one completed the exercise protocol without undue dyspnoea. Non-invasive exercise testing in patients with aortic stenosis may detect abnormalities of left heart function which are not apparent at rest. These abnormalities may provide early evidence either of severe aortic stenosis or of incipient left ventricular failure.     

Computerized echocardiographic analysis to detect abnormal systolic and diastolic left venticular function in children with aortic stenosis.

Experience with computer analysis of M mode echocardiograms for the evaluation of left ventricular function in patients with left ventricular pressure overload is reported. In order to study systolic and diastolic left ventricular function, endocardial surfaces of the septum and posterior wall were digitized and analyzed by minicomputer. The subjects included 52 normal children and 30 children with catheterization-proved aortic stenosis with (13) and without (17) coarctation. Compared with the normal children, the patients with aortic stenosis had a statistically smaller and thicker walled left ventricle and increased fractional shortening of the left ventricular minor axis. Continuous tracings of minor axis dimension and the first derivative of these tracings were plotted. The tracings allowed measurement of the maximal velocity of shortening and lengthening. Maximal velocity of shortening (normal = 96.8 ± 3 mm/sec [mean ± standard error of the mean]) was depressed to 80.8 ± 4.7 mm/sec) in the group with pressure overload. Maximal velocity of lengthening (normal = 116.4 ± 3 mm/sec) was also depressed (88.4 ± 5.2 mm/sec) in this group. Although the velocity measurements allowed separation of the normal from the abnormal group, they did not correlate closely with either left ventricular wall thickness or left ventricular systolic pressure and therefore they cannot be used to assess the severity of the left ventricular pressure overload or the need for surgical correction. Nonetheless, the study provides a method for analyzing left ventricular diastolic and systolic dynamic function from a ventricular M mode echo alone and suggests abnormal systolic and diastolic left ventricular performance in some children with aortic stenosis and left ventricular hypertrophy.     

Comparative study of left ventricular echocardiographic parameters in congenital aortic stenosis and coarctation

Left ventricular adaptation to obstruction to ejection (aortic stenosis and coarctation) was studied by echocardiography in 85 patients from 1 month to 20 years of age. Group I: 40 children with pure congenital aortic stenosis. Group II: 45 children with coarctation at the aortic isthmus without associated shunts. All patients also underwent cardiac catheterisation. The results were compared with a control series of 35 normal subjects. Echocardiographic recordings of adequate quality for studying the left ventricle and parameters of myocardial performance were obtained in all patients. In Group I estimations of the left ventricular systolic pressure and the ventriculo-aortic pressure gradient were made and compared to the results of catheterisation. Symmetric left ventricular hypertrophy was recorded in both groups (h/R, p less than 0,001; myocardial mass, p less than 0,001) but this was more common in aortic stenosis (92%) than in coarctation (53%). Left ventricular function was similar in both groups with an increased fractional shortening (p less than 0,001) and velocity of circumferential fibre shortening (p less than 0,001). Good correlations were obtained between echocardiographic and hemodynamic measurements of left ventricular pressures and ventriculo-aortic pressure gradients (pressure R = 0,83, gradient R = 0,73) using the formula for systolic left ventricular pressure = SLV = 225 X PPs/Ds. This proved very useful in assessing which children needed surgery.     

Echocardiographic left ventricular dimensions in pressure and volume overload. Their use in assessing aortic stenosis.

Left ventricular 'relative wall thickness', determined from the ratio between echocardiographic measurements of end-systolic wall thickness and cavity transverse dimension, was related to peak systolic intraventricular pressure in 15 normal subjects, in 15 patients with left ventricular volume or pressure overload without aortic stenosis, and in 23 patients with aortic stenosis. All these patients had a mean rate of circumferential fibre shortening greater than 1.0 circumference per second and were regarded as having good ventricular function. Relative wall thickness was found to be normal in cases of volume overload and to be increased in pressure overload, being proportional to the systolic intraventricular pressure. Values for the ratio of systolic intraventricular pressure to relative wall thickness in the normal subjects and patients without aortic stenosis were similar (mean 30 +/- 2.5). Based on this relation, estimates of peak systolic intraventricular pressure were made in the cases of aortic stenosis using the formula: systolic intraventricular pressure (kPa) equals 30 x wall thicknes divided by transverse dimension. Peak systolic aortic value gradients derived by subtracting brachial artery systolic pressure, measured by sphygmomanometer, from the echocardiographic estimates of intraventricular pressure compared favourably with the gradients measured at left heart catheterization (r equals 0.87, P less than 0.001). Aortic value orifice areas, derived from echocardiographic estimates of stroke volume, ejection time, and value gradient, ranged from 0.21 to 3.16 cm2 and appeared to correlate with the severity of aortic stenosis. All patients with aortic stenosis, with or without coexistent mild aortic regurgitation, who were recommended for aortic valve surgery, had estimated valve orifice areas of less than 0.8 cm2. A further 10 patients with pressure or volume overload had mean rates of circumferential fibre shortening of less than 1.0 circumference per second and were regarded as having poor ventricular function. In these cases values for relative wall thickness were lower than in those with good ventricular function and were not proportional to systolic intraventricular pressure. In patients with good left ventricular function systolic intraventricular pressure is proportional to, and can be estimated from, echocardiographic measurement of relative wall thickness.     

Echocardiographic left ventricular dimensions in pressure and volume overload. Their use in assessing aortic stenosis.

Left ventricular 'relative wall thickness', determined from the ratio between echocardiographic measurements of end-systolic wall thickness and cavity transverse dimension, was related to peak systolic intraventricular pressure in 15 normal subjects, in 15 patients with left ventricular volume or pressure overload without aortic stenosis, and in 23 patients with aortic stenosis. All these patients had a mean rate of circumferential fibre shortening greater than 1.0 circumference per second and were regarded as having good ventricular function. Relative wall thickness was found to be normal in cases of volume overload and to be increased in pressure overload, being proportional to the systolic intraventricular pressure. Values for the ratio of systolic intraventricular pressure to relative wall thickness in the normal subjects and patients without aortic stenosis were similar (mean 30 +/- 2.5). Based on this relation, estimates of peak systolic intraventricular pressure were made in the cases of aortic stenosis using the formula: systolic intraventricular pressure (kPa) equals 30 x wall thicknes divided by transverse dimension. Peak systolic aortic value gradients derived by subtracting brachial artery systolic pressure, measured by sphygmomanometer, from the echocardiographic estimates of intraventricular pressure compared favourably with the gradients measured at left heart catheterization (r equals 0.87, P less than 0.001). Aortic value orifice areas, derived from echocardiographic estimates of stroke volume, ejection time, and value gradient, ranged from 0.21 to 3.16 cm2 and appeared to correlate with the severity of aortic stenosis. All patients with aortic stenosis, with or without coexistent mild aortic regurgitation, who were recommended for aortic valve surgery, had estimated valve orifice areas of less than 0.8 cm2. A further 10 patients with pressure or volume overload had mean rates of circumferential fibre shortening of less than 1.0 circumference per second and were regarded as having poor ventricular function. In these cases values for relative wall thickness were lower than in those with good ventricular function and were not proportional to systolic intraventricular pressure. In patients with good left ventricular function systolic intraventricular pressure is proportional to, and can be estimated from, echocardiographic measurement of relative wall thickness.     

Influence of heart rate on systolic time intervals: Effects of atrial pacing versus dynamic exercise

The effects of atrial pacing and dynamic exercise in the supine position on systolic time intervals (STI) were compared in 10 normals. In another group of 13 normals, the effect of exercise alone on STI was tested. A linear shortening of electromechanical systole (QS₂) and left ventricular ejection time (LVET) with increasing heart rate was demonstrated with right atrial pacing and dynamic exercise in the frequency range between 60 and 140 beats/min. However, the shortening of LVET was significantly less (p<0.01) with exercise compared to pacing. This is explained by an increase in left ventricular stroke volume with exercise. The pre-ejection period (PEP) was significantly (p<0.001) shortened with exercise, but there was no change with atrial pacing. Thus, changes in heart rate (HR) alone, without changes in the dynamic state of the heart, did not influence PEP. It is suggested that PEP at rest should not be corrected for heart rate. The supine exercise regression equations for correction of heart rate for LVET and PEP differ from both the resting and the upright exercise regression equations. With exercise a frequency correction of STI using regression equations should be abandoned. Instead, uncorrected STI at standard heart rates (e.g., 100, 110, and 130 beats/min) should be taken for comparison. Heart rate standardization should be employed using the formula     

Comparison of echocardiographic methods for assessment of left ventricular shortening and wall stress

M-mode echocardiographic measurement of left ventricular fractional shortening and meridional wall stress has been used extensively alone and in combination to describe left ventricular systolic function. To determine whether the improved dimensional information afforded by two-dimensional echocardiography might result in shortening and stress calculations yielding a different view of left ventricular function, we compared two-dimensional and M-mode echocardiograms in 69 subjects (19 normal, 13 with aortic stenosis, 22 with aortic regurgitation and 15 with congestive cardiomyopathy). Fractional shortening was greater with M-mode than with two-dimensional echocardiography in all subjects, especially in those with cardiomyopathy (p less than 0.05). In aortic stenosis, two-dimensional shortening, at 24 +/- 5%, was reduced (p less than 0.05 versus normal), but M-mode shortening, at 34 +/- 5%, was not. M-mode estimates of meridional stress were higher than two-dimensional values, again especially in cardiomyopathy. Two-dimensional echocardiography enabled determination of long- and short-axis ratios, circumferential stress and the ratio of circumferential to meridional stresses. Circumferential stress was elevated in aortic stenosis at 302 +/- 65 X 10(3) dynes/cm2, suggesting afterload excess as the cause for the observed reduction in two-dimensional shortening. The more spherical cardiomyopathic hearts had a meridional to circumferential stress ratio closer to 1, such that use of meridional stress alone would overestimate effective afterload. It is concluded that M-mode and two-dimensional echocardiographic analyses of left ventricular shortening and stress produce different results. Two-dimensional echocardiographic methods may enhance the assessment of ventricular function, especially in patients with aortic stenosis and cardiomyopathy.     

Lack of correlation between exercise capacity and indexes of resting left ventricular performance in heart failure

Symptoms of congestive heart failure occur most commonly during exercise, but cardiac performance is usually quantitated at rest. The relation between exercise capacity and measurements of cardiac performance at rest is little known. Treadmill exercise was performed in 21 patients with heart failure due to cardiomyopathy. Exercise duration averaged 9.1 ± 0.7 (standard error of the mean) minutes (normal value 12 or more minutes) and did not correlate with resting ejection fraction of 26.4 ± 2.7 percent (r = ?0.06). Left ventricular diastolic dimension of 6.6 ± 0.2 cm, mean velocity of circumferential fiber shortening and ratio of preejection period to left ventricular ejection time did not correlate with treadmill time (r = ?0.03). Repeat studies after treatment of heart failure also failed to show correlations between changes in exercise capacity and changes in left ventricular performance at rest. Thus, measures of left ventricular performance obtained at rest do not accurately reflect exercise tolerance and symptomatic status of patients with congestive heart failure.     

Current status of radionuclide imaging in valvular heart disease

In valvular heart disease, there is a different radionuclide angiographic pattern in each of three left-sided valve abnormalities: pressure overload (aortic stenosis), volume overload (aortic or mitral regurgitation) and inflow obstruction (mitral stenosis). In pressure overload, the left ventricle is usually normal in size or minimally dilated. The ejection fraction may be normal, increased or decreased. In volume overload, there is left ventricular dilatation with a normal or reduced ejection fraction at rest. Scans may be performed during exercise to unmask abnormalities of ventricular function not evident at rest. In inflow obstruction, left ventricular function is usually normal but may be depressed. Right ventricular function may be abnormal secondary to pulmonary hypertension.

Radionuclide angiography in valvular heart disease evaluates the impact of the valve abnormality on cardiac chamber size and function, which is useful in managing the patient, in determining the prognosis and in evaluating the success of valve surgery. Thallium-201 imaging evaluates regional myocardial blood flow and cell integrity and can be used to assess associated coronary artery disease.     

Ventricular response to isometric and isotonic exercise. Echocardiographic assessment

The effects of supine isometric handgrip and graded isotonic bicycle ergometer exercise on left ventricular performance were studied echocardiographically in 20 normal subjects, aged 18 to 36. Measurements of the left ventricular minor axis diameter were taken from recordings performed at rest, during each form of exercise, and during recovery. At the completion of isometric exercise, the pressure-rate product increased significantly. There was no significant change in percentage of fractional shortening (%deltaD), while there was a small but significant fall in peak velocity of circumferential fibre shortening (peak Vcf). Isotonic exercise resulted in a significant increase in %deltaD and peak Vcf. The pressure-rate product also increased and showed a positive correlation with peak Vcf. Isotonic exercise produced a much greater stimulus to left ventricular contractility than isometric exercise and may be a useful means of detecting latent left ventricular dysfunction echocardiographically.     

Left ventricular adaptation to sustained pressure overload in the conscious dog

The early adaptation to aortic stenosis was studied in eight conscious dogs previously instrumented with a left ventricular micromanometer and ultrasonic crystals measuring left ventricular minor equator, left ventricular major axis, and ventricular wall thickness. Data were compared during control, acute inflation of a supravalvular aortic cuff occluder and 24 hours after aortic stenosis with and without beta-blockade. Acute aortic stenosis increased peak systolic pressure and end-systolic pressure with a decrease of percent systolic shortening of minor diameter (% delta L). Twenty-four hours after aortic constriction for heart rates, end-diastolic dimensions, and systolic pressures similar to those measured during acute aortic stenosis, % delta L was significantly increased, compared with acute aortic constriction, and was close to control values. End-systolic diameter was not significantly different from control during sustained pressure overload, although end-systolic stress was increased by 26.7 +/- 6.1% (P less than 0.01 with control), representing a leftward shift of the end-systolic stress-diameter relation. Similar results were obtained under beta-blockade. We conclude that there is, in this model of moderate pressure overload, a nonsympathetic increased inotropic state very early after aortic constriction.     

Cardiocyte cytoskeleton in patients with left ventricular pressure overload hypertrophy

OBJECTIVES: We sought to determine whether the cardiocyte microtubule network densification characteristic of animal models of severe pressure overload cardiac hypertrophy occurs in human patients. BACKGROUND: In animal models of clinical entities causative of severe right and left ventricular (LV) pressure overload hypertrophy, increased density of the cellular microtubule network, through viscous loading of active myofilaments, causes contractile dysfunction that is normalized by microtubule depolymerization. These linked contractile and cytoskeletal abnormalities, based on augmented tubulin synthesis and microtubule stability, progress during the transition to heart failure. METHODS: Thirteen patients with symptomatic aortic stenosis (AS) (aortic valve area = 0.6 +/- 0.1 cm2) and two control patients without AS were studied. No patient had aortic insufficiency, significant coronary artery disease or abnormal segmental LV wall motion. Left ventricular function was assessed by echocardiography and cardiac catheterization before aortic valve replacement. Left ventricular biopsies obtained at surgery before cardioplegia were separated into free and polymerized tubulin fractions before analysis. Midwall LV fractional shortening versus mean LV wall stress in the AS patients was compared with that in 84 normal patients. RESULTS: Four AS patients had normal LV function and microtubule protein concentration; six had decreased LV function and increased microtubule protein concentration, and three had borderline LV function and microtubule protein concentration, such that there was an inverse relationship of midwall LV fractional shortening to microtubule protein. CONCLUSIONS: In patients, as in animal models of severe LV pressure overload hypertrophy, myocardial dysfunction is associated with increased microtubules, suggesting that this may be one mechanism contributing to the development of congestive heart failure in patients with AS.     

Effects of calcium antagonist, angiotensin-converting enzyme inhibitors and beta-blocker on hemodynamic and sympathetic nerve responses to exercise in essential hypertension]

To investigate the effects of antihypertensive drugs on hemodynamic and sympathetic nerve responses to exercise, graded ergometer exercise tests were performed before and after two-week administration of nifedipine, captopril and metoprolol in 18 patients with essential hypertension. The arterial pressure, heart rates (HR), and left ventricular functions as obtained by echocardiography, and the plasma norepinephrine (PNE) levels, were evaluated at rest and during submaximal exercise before and after two-week treatment with nifedipine (40 mg/day, 5 cases), captopril (37.5-75 mg/day, 6 cases) and metoprolol (60 mg/day, 7 cases). These 3 drugs significantly reduced systolic (SBP) and diastolic (DBP) blood pressures but caused no significant changes in resting PNE levels. Nifedipine produced no significant changes in HR and cardiac output (CO) at rest, but augmented the increase in HR (delta HR) and SBP (delta SBP) during submaximal exercise. The increase in PNE (delta PNE) was also augmented by nifedipine. Captopril reduced left ventricular end-diastolic volume and CO without changes in HR and fractional shortening (FS) at rest; whereas, it did not affect delta HR, delta CO, delta SBP or delta PNE during exercise. Metoprolol reduced HR and CO at rest, and also resulted in a decrease in delta FS and delta CO during submaximal exercise. delta SBP was unchanged and delta PNE was increased by treatment with metoprolol. These results indicate that, in hypertensive subjects, the effects on the hemodynamic and sympathetic nerve responses to exercise are different among these 3 antihypertensive drugs despite their identical effects on blood pressure.     

Echocardiographic dimensions of the left ventricle during ergometric exercise: results in normal subjects (author's transl)

10 healthy men aged 18 to 32 years underwent M-mode-echocardiographic studies at rest, during exercise and recovery. Semisupine bicycle exercise was performed using work loads of 25, 50, 75, and 100 W with measurements taken every minute. With increasing exercise, heart rate rose significantly (p less than 0.01) from 68/min to a maximum of 132/min, blood pressure as obtained by sphygmomanometry rose from a mean of 83 torr to 102 torr. Left ventricular enddiastolic dimension (EDD) did not change significantly with exercise, left ventricular endsystolic dimension (ESD) decreased from a group mean of 34.8 mm to 30.5 mm. This paralleled an increase in stroke dimension from 18.3 to 22.6 mm and of fractional shortening (FS) from 0.34 to 0.43. Mean velocity of circumferential fiber shortening (MVCF) rose from 1.01 circ/s to 2.06 circ/s. During recovery, heart rate and blood pressure returned faster to resting levels than did ESD, FS, and MVCF. Again EDD did not change. These data indicate that heart rate contributes more to the increases in cardiac output observed with ergometric exercise than does stroke volume; with moderate exercise levels this increase in stroke volume is produced by diminishing endsystolic volume whilst enddiastolic volume remains unchanged.     

Left ventricular wall stress and function in childhood coarctation of the aorta

Unlike most adults with compensated pressure overload of the left ventricle, children with moderate to severe aortic stenosis exhibit pronounced left ventricular muscle hypertrophy, enhanced ejection performance and diminished wall stress. To determine whether these findings are present in other forms of left ventricular pressure overload in children, left ventricular mechanics were studied by catheterization in 14 children with coarctation of the aorta (average peak gradient 39 +/- 17 mm Hg) and in 10 normal children. Ejection fraction and mean velocity of circumferential fiber shortening in the coarctation group (0.74 +/- 0.09 and 1.71 +/- 0.43 circumferences/s, respectively) were significantly higher than in normal subjects (0.65 +/- 0.05 and 1.27 +/- 0.26 circumferences/s, respectively) (p = 0.008), but the ranges for both groups overlapped. End-systolic stress in children with coarctation (77 +/- 20 dynes X 10(3)/cm2) was less than in normal children (121 +/- 24 dynes X 10(3)/cm2) (p less than 0.001), again with overlap of the ranges for both groups. The ratio of end-systolic stress to end-systolic volume index, an estimate of contractile function, was similar in both groups. Relations between severity of obstruction (left ventricular peak systolic pressure, coarctation gradient) and end-systolic stress and between stress and ejection performance were present within the coarctation group. Comparison of these data with those found in children with moderate to severe aortic stenosis shows a similar but less pronounced response to pressure overload due to coarctation of the aorta.     

Systolic stress in mitral stenosis

Left ventricular systolic stress was studied in nineteen patients with mitral stenosis, twelve in sinus rhythm and seven in atrial fibrillation. Left ventricular dimensions and volumes and septal and posterior wall thickness were measured by means of M and two bidimensional echocardiography at rest and during isometric exercise. Expulsive indices: fractional shortening, ejection fraction and mean circumferential shortening rate were calculated. Ventricular mass, meridional stress and several end-systolic stress or pressure/volume relationships were estimated. Patients with atrial fibrillation were older and had systolic dysfunction: greater end-systolic volumes and depression of both expulsive fractions and some of the end-systolic indices. Preload and wall thickness were normal. Patients with atrial fibrillation showed higher ventricular stress as a consequence of greater ventricular dimensions. Ejection fraction correlates directly with mitral valve area and inversely with inotropic state and heart rate. It is concluded that systolic dysfunction in mitral stenosis is multifactorial. The most important determinants of the abnormality are heart rate and inotropic state. The study did not show any primary abnormality of afterload or hypotrophy of the left ventricle.