Early diastolic left ventricular function in children and adults with aortic stenosis

Left Ventricular Remodeling and Function in Children with Biventricular Circulation After Fetal Aortic Valvuloplasty

Fetal aortic valvuloplasty (FAV) has shown promise in averting the progression of fetal aortic stenosis to hypoplastic left-heart syndrome. Altered loading conditions due to valvar disease, intrinsic endomyocardial abnormalities, and procedures that alter endomyocardial mechanics may place patients with biventricular circulation (BiV) after FAV at risk of abnormal LV remodeling and function. Using the most recent echo data on BiV patients after technically successful FAV (n = 34), we evaluated LV remodeling pattern, risk factors for pathologic LV remodeling, and the association between LV remodeling pattern and LV function. Median age at follow-up was 4.7 years (range 1.0-12.5). Cardiac interventions were common. At latest follow-up, no patient had hypoplastic LV. Nineteen patients (55 %) had dilated LV, and five (16 %) patients had severely dilated LV. LV remodeling patterns were as follows: 12 (35 %) normal ventricle, 11 (32 %) mixed hypertrophy, 8 (24 %) eccentric hypertrophy or remodeling, and 3 (9 %) concentric hypertrophy. Univariate factors associated with pathologic LV remodeling were long-standing AR, ≥2 cardiac interventions, EFE resection, and aortic or mitral regurgitation ≥ moderate at most recent follow-up. In multivariate analysis, only long-standing AR fraction remained associated with pathologic remodeling. Pathologic LV remodeling was associated with depressed ejection fraction, lower septal E´, and higher E/E´. Pathologic LV remodeling, primarily eccentric or mixed hypertrophy, is common in BiV patients after FAV and is related to LV loading conditions imposed by valvar disease. Pathologic remodeling is associated with both systolic and diastolic dysfunction in this population.

Left ventricular response to pressure afterload in children: aortic stenosis and coarctation: a systematic review of the current evidence

Congenital aortic stenosis (CAS) and Coarctation of Aorta (CoA) represent two forms of pressure afterload that affect the left ventricle (LV), hence require regular echocardiographic monitoring. Subclinical dysfunction of the LV exists even in asymptomatic patients with preserved left ventricular ejection fraction (EF), implying low sensitivity of EF in predicting optimum time for intervention. In this article we review patterns of LV myocardial deformation before and after correction of CAS and CoA in infants, children and adolescents, showing their important role in monitoring the course of LV dysfunction. A systematic search using PubMed was performed and suitable studies are presented on a narrative form. Normal EF and/or fractional shortening (FS), with subclinical myocardial dysfunction are reported in all studies before intervention. The short-term results, after intervention, were related to the type of procedure, with no improvement or further deterioration related to surgery but immediate improvement after balloon intervention. Long term follow-up showed further improvement but still subnormal function. Thus correction of CAS and CoA before irreversible LV dysfunction is vital, and requires longitudinal studies in order to identify the most accurate parameter for function prognostication. Until then, conventional echocardiographic parameters together with myocardial velocities and deformation parameters should continue to provide follow-up reproducible measures of ventricular function.

Left ventricular diastolic function in children and young adults with congenital aortic valve disease

Young patients with congenital aortic valve disease are at risk of left ventricular (LV) diastolic dysfunction (DD). We evaluated LV remodeling and the prevalence of, and risk factors for, DD in patients with aortic stenosis (AS), pure aortic regurgitation (AR), and AS+AR. Patients aged 8 to 39 years with congenital AS (n = 103), AR (n = 36), or AS+AR (n = 107) were identified. Cross-sectional assessment of the LV remodeling pattern and diastolic function was performed. A diastolic function score (DFS; range 0 to 4) was assigned to each patient, with 1 point for an abnormal value in each of 4 categories: mitral inflow (E/A and E-wave deceleration time), tissue Doppler E', E/E', and left atrial volume. Patients with a DFS of ≥2 were compared to those with a DFS <2. Concentric hypertrophy was the most common remodeling pattern in those with AS (51%), mixed/physiologic hypertrophy in those with AS+AR (48%) and eccentric hypertrophy in those with AR (49%) predominated. In the entire cohort, 91 patients (37%) had a DFS of ≥2. Patients with AS or AS+AR had greater DFS than those with pure AR (p <0.001). On multivariate analysis, a greater LV mass z-score and previous aortic valve balloon dilation were associated with a DFS of ≥2. In patients with catheterization data (n = 65), E/E' correlated with LV end-diastolic pressure. Those with a DFS of ≥2 had a greater LV end-diastolic pressure and mean pulmonary artery pressure than those with a DFS <2. In conclusion, DD is common in young patients with AS and AS+AR but not in those with pure AR. A greater LV mass and previous aortic valve dilation were associated with DD.

Left ventricular remodeling and improvement in diastolic function after balloon aortic valvuloplasty for congenital aortic stenosis

BACKGROUND

In congenital aortic stenosis, chronic pressure load has detrimental effects on left ventricular (LV) systolic and diastolic function. Reduction in LV pressure load with balloon aortic valvuloplasty (BAVP) may improve diastolic function.

METHODS AND RESULTS

Echocardiographic and catheterization data for 25 consecutive patients undergoing BAVP for congenital aortic stenosis were retrospectively analyzed. Median age at BAVP was 11.5 years (3.2-40.1). LV end-diastolic pressure was elevated (≥15 mm Hg) in 72% of patients, with a median of 17 mm Hg (range, 9-24). With BAVP, median aortic stenosis gradient was reduced from 63 mm Hg (range, 44-105) to 30 mm Hg (range, 10-43). Aortic regurgitation increased from trivial (none to mild) to mild (trivial to moderate). Pre-BAVP early diastolic mitral inflow velocity/tissue Doppler early diastolic velocity (E/E´) correlated with LV end-diastolic pressure (r=0.52, P=0.007). On follow-up echocardiography (median, 11 months after BAVP), aortic stenosis gradient was lower (P<0.001) and degree of AR was higher (P=0.01) compared with pre-BAVP echocardiograms. LV end-diastolic volume z-score increased (P=0.02), LV mass was unchanged, and LV mass:volume decreased (P=0.002). Mitral annular and septal E´ (P<0.001) were higher and E/E´ was lower after dilation (10.8 versus 14.2, P<0.001). Lower pre-BAVP E/E´ and lower pre-BAVP LV mass z-score were associated with lower post-BAVP E/E.

CONCLUSION

After BAVP, LV remodeling characterized by an increase in EDV and decrease in LV mass:volume occurs and echocardiographic measures of diastolic function and LV end-diastolic pressure improve in most patients. Risk factors for persistent diastolic dysfunction include higher pre-BAVP LV mass z-score and worse pre-BAVP diastolic function.

Postnatal left ventricular diastolic function after fetal aortic valvuloplasty

Fetal aortic balloon valvuloplasty (FAV) has shown promise in altering in utero progression of aortic stenosis to hypoplastic left heart syndrome. In patients who achieve a biventricular circulation after FAV, left ventricular (LV) compliance may be impaired. Echocardiographic indexes of diastolic function were compared between patients with biventricular circulation after FAV, congenital aortic stenosis (AS), and age-matched controls. In the neonatal period, patients with FAV had similar LV, aortic, and mitral valve dimensions but more evidence of endocardial fibroelastosis than patients with AS. Patients with FAV underwent more postnatal cardiac interventions than patients with AS (p = 0.007). Mitral annular early diastolic tissue velocity (E') was lower in patients with FAV and those with AS and controls in the neonatal period and over follow-up (p <0.001). Septal E' was similar among all 3 groups in the neonatal period. In follow-up patients, with FAV had lower septal E' than patients with AS or controls (p <0.001). Early mitral inflow velocity/E' was higher in patients with FAV as neonates and at follow-up (p <0.001). Mitral inflow pulse-wave Doppler-derived indexes of diastolic function were similar between groups. In conclusion, echocardiographic evidence of LV diastolic dysfunction is common in patients with biventricular circulation after FAV and persists in short-term follow-up. LV diastolic dysfunction in this unique population may have important implications on long-term risk of left atrial and subsequent pulmonary hypertension.

Titin isoform expression in aortic stenosis

Titin is a giant sarcomeric protein that plays a major role in determining passive myocardial stiffness. The shorter N2B isoform results in a higher passive myocardial stiffness than the longer N2BA isoform. We hypothesised that the expression of the short N2B isoform would be increased in patients with aortic stenosis compared with healthy controls in response to pressure overload, in order to act as a modulator for the increased demand placed on the left ventricle during the early stages of the hypertrophic response. Myocardial biopsies were obtained from the left ventricle of 19 patients undergoing aortic valve replacement for aortic stenosis who had no significant co-existing coronary artery disease. Left ventricular biopsies were also obtained from 13 donor hearts for comparison. SDS-agarose gels revealed small N2B and large N2BA cardiac titin isoforms, with a mean N2BA/N2B ratio that was significantly decreased in the 19 aortic stenotic patients compared with the 13 controls (0.66+/-0.04 in the normal donor hearts compared with 0.48+/-0.03 in patients with aortic stenosis; P=0.02). However, total titin remained unchanged (0.28+/-0.02 compared with 0.24+/-0.02 respectively; P=0.29). In conclusion, the expression of less N2BA and more N2B titin in response to pressure overload may result in the generation of higher passive tension upon stretch to a given sarcomere length and this might affect cardiac performance.

Left ventricle myocardial mechanics and textural properties in patients with Williams syndrome

OBJECTIVE

To study left ventricular mechanics and textural properties in patients with Williams syndrome to define the impact of left ventricular hypertrophy on the functional findings.

METHODS

Echocardiography was performed in 16 Williams syndrome patients (aged 1-25 years, mean 10 +/- 6 years), four with associated supravalvular aortic stenosis and seven with systemic hypertension. Fifteen age- and body surface area-matched subjects were selected as control group. Particularly, left ventricular geometry, myocardial contractility [midwall rate-corrected circumferential fiber shortening/end-systolic meridional wall stress relationship (sigmaes)] and left ventricular diastolic function (mitral flow pattern and isovolumic relaxation time) were defined. In addition, integrated backscatter (IB) analysis intensity (IntIB) and cyclic variation (CVIB) were assessed for an ultrasonic myocardial characterization.

RESULTS

Left ventricular hypertrophy was demonstrated in nine patients (56%) and abnormal left ventricular remodeling in ten patients (62%). Particularly seven of seven hypertensive patients and three of four patients with supravalvular aortic stenosis had abnormal remodeling; left ventricular geometry was normal in patients without hypertension or supravalvular aortic stenosis. In addition, midwall rate-corrected circumferential fiber shortening/(sigmaes) relationship was within the normal range in all patients. At integrated backscatter analysis, Williams syndrome patients showed, both at interventricular septum and posterior wall, reduced CVIB (9.36 +/- 2.16 versus 10.3 +/- 1.3 and 8.65 +/- 2 versus 10.5 +/- 1.1). Compared to Williams syndrome patients without left ventricular hypertrophy (7/16), those with left ventricular hypertrophy (9/16) showed decreased mitral E/A ratio (1.32 +/- 0.09 versus 1.62 +/- 0.02), increased isovolumic relaxation time (68 +/- 7 versus 53 +/- 7) and increased IntIBS at interventricular septum (-27.3 +/- 0.07 versus -34 +/- 5).

CONCLUSIONS

Our data obtained in young Williams syndrome patients show that: (i) mild left ventricular functional and textural abnormalities may be detected also in absence of significant supravalvular aortic stenosis and/or hypertension; (ii) significant left ventricular hypertrophy may develop since childhood; (iii) differences in left ventricular remodeling and/or degree of left ventricular hypertrophy may occur. Further studies are required to define the real impact of the functional abnormalities on the natural history in patients with Williams syndrome.

Adaptive mechanisms of left ventricular diastolic function to the physiologic load of pregnancy

BACKGROUND

Pregnancy is associated with marked alteration in cardiovascular hemodynamics. Recent reports have characterized the effects on cardiac systolic function. Little has been written on the influences of loading conditions on Doppler measures of diastolic function during pregnancy.

HYPOTHESIS

Stage of pregnancy has an impact on Doppler indices of diastolic function independent of loading conditions, systolic function, and heart rate.

METHOD

Thirty healthy women were prospectively evaluated by serial echocardiography and Doppler examinations at six time periods: 10-12, 18-20, 28-30, 36-38 weeks gestation, 2-4 and 12-14 weeks postpartum. The related effects on indices of diastolic function and its interaction with load, heart rate, mass, and systolic function were determined.

RESULTS

Compared with the nonpregnant state, early (E) velocity increased (0.7+/-0.1-0.9+/-0.1 m/s, p = 0.0001), peaking at 18 weeks and returning to normal levels during late pregnancy. Atrial phase (A) velocity peaked at 18 weeks (0.48+/-0.12-0.60+/-0.13 m/s, p = 0.0001), remaining high throughout the rest of pregnancy. Consequently, the EWA ratio fell significantly during late pregnancy, from 1.9+/-0.4 to 1.4+/-0.3 (p = 0.02). In addition, mean acceleration was significantly increased in early pregnancy with a peak at 18 weeks (7.4+/-1.3 m/s2), returning to nonpregnant level at term (5.7+/-1.4 m/s2, p = 0.0001). Generalized estimating equation using multivariate regression analysis demonstrated that rising heart rate and stroke volume index had an independent effect on A velocity, and that contractility and preload had an independent effect on E velocity. Pregnancy itself had an independent influence on early filling, not explained by the other parameters.

CONCLUSIONS

During normal pregnancy, there is a reversible shift in transmitral flow velocities from early to late filling with a decrease in acceleration, consistent with an increase in ventricular compliance. Changes in heart rate, preload, and contractility, as well as stage of pregnancy influence this alteration.

Doppler echocardiographic assessment of left ventricular filling pressures in elderly patients with moderate/severe aortic stenosis

Doppler-derived mitral inflow indices reflect left ventricular (LV) filling pressures but often vary with age. Diastolic filling is impaired in LV pressure overload states. The objective of this study was to determine the influence of age on the relationship between mitral inflow indices and LV filling pressures in patients with aortic stenosis. The authors studied 57 consecutive patients (age, 77 years; 52% male) with moderate to severe aortic stenosis (aortic valve area < or =1.0 cm(2)) on cardiac catheterization and echocardiographic studies performed within 48 hours of catheterization. Patients with atrial fibrillation, aortic insufficiency, mitral stenosis, and paced rhythm were excluded. Echocardiographic variables obtained from five cardiac cycles were: E/A ratio and deceleration time (DT). Patients were subclassified by age (< and > or =75 years), ejection fraction ([EF] < and > or =50%), and coronary artery disease (CAD). Pulmonary capillary wedge pressure (PCWP) correlated with DT (r=-0.86; p=0.001) and with E/A (r=0.7; p=0.001) more strongly than did LV end-diastolic pressure. Age did not alter the relationship between DT and PCWP (r=-0.92; p=0.001 for < 75 years vs. r=-0.83; p=0.001 for > or =75 years). PCWP was predicted by the equation PCWP=-0.10DT+43, regardless of age. EF also had little influence on the correlation between PCWP and DT (r=-0.80; p=0.001 for EF < 50% vs. r=-0.94; p=0.001 for EF > or =50%). Similarly, there were no significant differences between the regression equations and correlations between the CAD and no-CAD groups: for CAD patients, PCWP=41.8-0.10DT; p < 0.0001; r=-0.84 (p < 0.0001). For no-CAD subjects, PCWP=46.2-0.12DT; p < 0.0001; r=20.92 (p < 0.0001). In patients with significant aortic stenosis, DT correlated strongly with PCWP but not with LV end-diastolic pressure. This relationship was independent of age, CAD, or EF.

Effect of left ventricular wall mass on Doppler filling patterns in the developing normal human heart

To assess gestational age- and growth-related changes in left ventricular (LV) size, LV wall, and LV transmitral flow velocity patterns, 2-dimensional (2-D) and Doppler echocardiographic studies were performed in 89 normal fetuses aged 16 to 38 weeks. Serial studies were designed in 7 fetuses. Variables measured from 4-chamber views were chamber areas and myocardial wall areas. From these measurements, area shortening fraction and ratio of myocardial wall area to end-diastolic chamber area were calculated. LV end-diastolic chamber area and myocardial wall area increased exponentially with advancing gestational age (r = 0.88 and 0.90, respectively, p < 0.001). Area shortening fraction showed no significant changes with gestational age. Ratio of myocardial wall area to LV end-diastolic chamber area decreased gradually with increasing gestational age (r = -0.77, p < 0.001). With increasing gestational age, mitral peak velocities of early diastole increased (r = 0.82, p < 0.01) with little change in peak velocity during atrial contraction. Multiple regression analysis showed that age-related increases in peak velocity of early diastole were related to advancing gestational age and also to decreases in ratio of myocardial wall area to LV end-diastolic chamber area. Low peak filling velocities during early diastole in younger fetuses may be related partly to relative increase in LV wall mass. The gestational age-related decreases in LV wall mass may be one of the important mechanisms of gestational age-related alterations in diastolic properties, especially relaxation processes.

Diastolic dysfunction in patients with congenital heart disease

As noted in the introduction of this article, a comprehensive evaluation of diastolic function in all known congenital heart defects is not feasible; however, by demonstrating several representative anatomic and genetic abnormalities where diastolic dysfunction may have clinical significance, it is hoped that scaffolding has been established which will provide structure for further study on this intriguing and influential component of function in patients with CHD. Understanding the contribution of diastole to overall ventricular function may be shown to have important implications in the recommendations for timing or potential benefit of surgical intervention. Or, to state differently, if diastolic dysfunction precedes that of systolic, would a rigorous analysis of diastole in the presurgical patient provide a more sensitive algorithm for intervention? The means for noninvasive assessment of diastolic function, primarily by spectral Doppler echocardiography, or using echocardiography in conjunction with other modalities, should allow for a comprehensive accrual of data in this patient population.

Effect of myocardial hypertrophy on systolic and diastolic function in children: insights from the force-frequency and relaxation-frequency relationships

OBJECTIVE

The objective of this study was to evaluate the effect of myocardial hypertrophy on systolic and diastolic properties of the left ventricle in children.

BACKGROUND

In children with myocardial hypertrophy, ejection phase indices are invariably increased. However, indices of force-generation, e.g., end-systolic elastance and invasive indices of diastolic properties, have been studied infrequently in children with myocardial hypertrophy.

METHODS

We studied 10 children with congenital aortic stenosis or coarctation of aorta and nine control patients. Systolic properties were assessed from shortening fraction, end-systolic fiber elastance (Ef(es)) measured at resting heart rates, and force-frequency relationship measured at heart rates increasing from 110 to 160 beats per minute. Diastolic properties were assessed from time constant of relaxation (tau) at matched heart rates, chamber stiffness constant, myocardial stiffness constant, and relaxation-frequency relationship measured at gradually increasing heart rates.

RESULTS

Ef(es) remained unchanged by myocardial hypertrophy, however, tau was prolonged (tauL: 27.3+/-2.3 vs. 21.8+/-2.2 ms, p < 0.001; and tauD: 43.2+/-3.1 vs. 34.3+/-3.3 ms, p < 0.001). Both chamber and myocardial stiffness constants remained unchanged. Incremental increases in heart rate produced incremental improvement in both contraction and relaxation. Slopes of force-frequency and relaxation-frequency relationships remained unchanged in the experimental group. However, the relaxation-frequency relationship manifested a parallel shift upward.

CONCLUSIONS

In conscious, sedated children with myocardial hypertrophy, systolic function assessed by an index of force generation remains unchanged. However, relaxation is prolonged but passive diastolic properties remain unaffected. The combined effect of hypertrophy and heart rate does not alter the force-frequency and relaxation-frequency relationships.

Reversibility of cardiac dysfunction after valve replacement in elderly patients with severe aortic stenosis

BACKGROUND

The role of aortic valve replacement for aortic stenosis has not been fully defined in terms of the postoperative reversibility of cardiac dysfunction and pulmonary hypertension in elderly patients.

METHODS

Cardiac function, assessed by radioisotope ventriculography and catheterization data, was evaluated before and after operation, and their results were compared between preoperative and postoperative data in each group of younger patients (<69 years, group I, n = 29) and elderly patients (> or =70 years, group II, n = 21).

RESULTS

One month postoperatively the peak ejection rate determined by radioisotope ventriculography improved significantly in comparison with the preoperative value in elderly patients (preoperatively, 228 +/- 38 versus postoperatively, 319 +/- 116% end-diastolic volume per second, p < 0.05), although their preoperative peak ejection rate was severely depressed. The postoperative peak filling rate of the elderly group was not completely reversible to almost normal value, whereas that of the younger group was completely reversible. Early diastolic peak filling rate (one-third peak filling rate) was not reversible in both two groups. Pulmonary hypertension in the elderly patients was reversible to postoperative almost normal pulmonary artery pressure despite the severity of aortic stenosis (systolic pulmonary artery pressure preoperatively, 37 +/- 16 mm Hg versus postoperatively, 25 +/- 5 mm Hg, p < 0.02; diastolic pulmonary artery pressure preoperatively, 15 +/- 6 mm Hg versus postoperatively, 10 +/- 4 mm Hg, p < 0.05).

CONCLUSIONS

Both cardiac dysfunction, reflected by reduction of peak ejection rate, and pulmonary hypertension in elderly patients with severe aortic stenosis were reversed, reaching almost normal values 1 month after operation.

Role of left ventricular mass/volume ratio on transmitral flow velocity patterns from infancy to childhood

Age-related changes in left ventricular diastolic filling have been reported to occur in normal children in studies using Doppler echocardiographic methods. However, little information currently exists on the relationships between transmitral flow velocity patterns and the left ventricular mass. We measured left ventricular end-diastolic volume, left ventricular mass, mass/volume ratio, and transmitral flow velocity patterns by M-mode and Doppler echocardiography in 165 normal children aged 5 days to 195 months. Subjects were divided into 6 age groups: <1; 1 to <3; 3 to <5; 5 to <7; 7 to <9; and > or = 9 years old. The left ventricular end-diastolic volume and mass increased progressively with increasing age. However, the mass/volume ratio in infants <1 year was significantly higher than that in infants 1 to <3 years (1.32+/-0.25 vs. 1.14+/-0.16, p<0.01) without any changes of the ratio thereafter. The peak E wave in infants <1 year was significantly lower than that in 1 to <3 years (71+/-18 vs. 92+/-13 cm/s, p<0.01) without changes thereafter. As the flow velocity time integral of E wave increased and that of A wave remained constant, the flow velocity time integral of E/A wave increased with increasing age. The early diastolic tilling fraction in infants <1 year was lower than that in infants 1 to 3 years. (0.61+/-0.07 vs. 0.70+/-0.06, p<0.01). The atrial filling fraction in infants <1 year was higher than that in infants 1 to <3 years (0.40+/-0.08 vs. 0.30+/-0.06, p<0.01) with a little decrease thereafter. The peak E wave, early diastolic tilling fraction, and the atrial filling fraction correlated with the logarithm of age (p<0.01). Age-related changes in these Doppler echocardiographic findings suggest reduced left ventricular early diastolic filling patterns. The mass/volume ratio correlated linearly with peak E wave, early diastolic filling fraction, and atrial filling fraction (r=-0.38, -0.33, and 0.26, p<0.01). No significant relationships between mass/volume ratio and the other Doppler indices were found. Thus, the age-related reduction in the mass/volume ratio may be one of the mechanisms underlying age-related changes in the early diastolic ventricular filling as assessed by Doppler echocardiography.

Prediction of the Third and Fourth Heart Sounds by Doppler Echocardiography

Doppler echocardiographic variables were sought for predicting the third and fourth heart sounds, as documented by phonocardiography. Phonocardiographic recordings of gallop sounds and Doppler echocardiographic investigations of mitral inflow and pulmonary venous flow were evaluated in 85 subjects by discriminant and multiple regression analysis. Of 85 subjects 47% had a third sound and 72% a fourth sound, evaluated by phonocardiography. A correct identification of 85% subjects with, and 82% without, the third sound was possible by discriminant analysis using the ratio of peak early diastolic to peak atrial mitral flow velocity (FV), the interval from peak ECG R wave to peak early diastolic mitral FV, and the early diastolic mitral FV deceleration time. At the observed prevalence of the third heart sound (47%), the predictive positive value was 81% and the predictive negative value was 86%. A correct identification of 72% of the subjects with, and 83% without, a fourth sound was possible by discriminant analysis using the ratio of peak early diastolic to peak atrial mitral FV, the interval between the end of atrial mitral FV and the peak ECG R wave, and the duration of pulmonary venous reverse FV at atrial systole. At the observed prevalence of the fourth heart sound (72%) the predictive positive value was 92% and the predictive negative value was 54%. By multiple regression analysis, up to 50% of the amplitude of both gallop sounds was predictable by a combination of Doppler echocardiographic variables.

Systolic and diastolic effects of variable atrioventricular delay in patients with complete heart block and normal ventricular function

This study was designed to demonstrate the effects of varying the atrioventricular delay (AVD) on ventricular diastolic filling dynamics and the resultant stroke volume in patients with complete heart block and normal cardiac function. We studied 7 patients with normal cardiac function in whom a dual chamber pacemaker had been implanted because of complete heart block. Doppler and M-mode echocardiography was performed at 70, 100, 140, 180, and 220 ms, AVD with the device in DDD mode at a rate of 80 beats/min. The effects of these variable intervals on the contribution of the E and A waveform to the diastolic filling, on the stroke volume, and on the systolic intervals were evaluated. Optimization of this interval, with a 19% increase in stroke volume was achieved in the group of patients at an AVD of 140 ms. When considered individually, the AVD associated with the largest stroke volume, was 100 ms in 2 patients and 140 ms in the remaining 5. At this individual optimal AVD the ventricular septal contraction occurred 31 +/- 14 ms, before the end of the transmitral flow. The optimal AVD is, therefore, the one which synchronizes the ventricular and atrial systole so that the first ventricular septal contraction occurs after the peak of the A wave, just before the end of the transmitral flow. Because of the different functional cardiovascular status of the single patient, this parameter should be individualized; this can be clinically important as it may lead, in this patient population, to an improvement of the stroke volume up to 42%.

Left ventricular mass, geometry, and filling in endurance athletes: association with exercise blood pressure

We studied whether left ventricular (LV) mass and concentricity [relative myocardial volume (RMV)] are associated with exercise blood pressure (BP) in athletes. LV structure and filling were evaluated by Doppler echocardiography and BP in maximal bicycle ergometry and isometric handgrip tests on 32 male endurance athletes and 15 age-matched controls. Indexed LV mass was 145 +/- 14 (SD) g/m in athletes and 93 +/- 20 g/m in controls. Mass was not associated with BP at rest or in low-grade exercise, but with heavier exercise loads this association strengthened in athletes, being maximal at peak exercise (r = 0.65 for mass and 0.58 for indexed mass; P < 0.001). Multivariate analysis indicated that BP at peak exercise accounted for 34% and the amount of training for an additional 11% of the variance in indexed LV mass. RMV was 21% larger in athletes. Only the increase in systolic BP during handgrip explained significantly (19%) the variance in RMV. LV filling velocities were not associated with mass, RMV, or BP. We conclude that in endurance athletes LV mass is associated with BP in heavy dynamic exercise and LV concentricity with BP response in static exercise.

Exercise capacity and systolic and diastolic ventricular function after recovery from acute dilated cardiomyopathy

OBJECTIVES

This study was undertaken to determine whether abnormalities in exercise capacity or ventricular function persist after recovery from acute dilated cardiomyopathy.

BACKGROUND

Persistent ventricular structural abnormalities could cause abnormalities in exercise capacity or ventricular function.

METHODS

The results of rest and exercise first-pass radionuclide ventriculography in 18 patients who were seen within 6 months of the onset of dilated cardiomyopathy and subsequently had a normal rest left ventricular ejection fraction were compared with those of age- and gender-matched control subjects.

RESULTS

Patients were studied 144 +/- 34 (mean +/- SEM) days after the onset of left ventricular dysfunction at a time when heart failure symptoms had resolved. Patients with myocyte necrosis, as assessed by endomyocardial biopsy (n = 13) or antimyosin scintigraphy (n = 12), recovered more rapidly than did those without necrosis. Oxygen consumption both at peak exercise (17.7 +/- 1.2 vs. 26.1 +/- 1.5 ml/kg per min, p < 0.05) and at the anaerobic threshold (11.1 +/- 0.5 vs. 17.1 +/- 1.3 ml/kg per min, p < 0.05) was lower in the patients who had recovered from cardiomyopathy than in control subjects. Rest and exercise end-systolic and end-diastolic left ventricular volumes were greater in the patients than in the control subjects, although stroke volumes were similar. Left ventricular filling at rest was lower at diastolic filling intervals of 40% and 90%, and rest and exercise left ventricular early peak filling rate normalized for end-diastolic volume was slower in the patients than in the control subjects. At long-term follow-up of 1,082 +/- 206 days, two patients had a return of heart failure symptoms and a decrease in left ventricular ejection fraction.

CONCLUSIONS

Despite the apparent normalization of rest left ventricular ejection fraction, patients who have recovered from dilated cardiomyopathy have abnormalities in aerobic exercise capacity and in left ventricular systolic and diastolic performance.

Quantitative hemodynamics by Doppler echocardiography: a noninvasive alternative to cardiac catheterization

Doppler echocardiography has greatly enhanced the information provided by two-dimensional echocardiography. By providing information concerning pressure gradients, intracardiac pressures, volumetric flow, and diastolic filling of the heart, most hemodynamic information that in the past could be obtained only from cardiac catheterization can now be provided accurately and noninvasively by Doppler echocardiography. Future developments in instrument technology and understanding of the various Doppler velocity curves should further aid in the ability to obtain a complete, noninvasive hemodynamic assessment of the patient with cardiac disease.

Doppler evaluation of normalized peak filling rate in normal children and children with left ventricular outflow obstruction

To evaluate the early diastolic peak filling rate of the left ventricle, three groups of children (normal children, patients with aortic valvular stenosis, and patients with aortic coarctation) were examined with the peak filling rate normalized to stroke volume calculated from the mitral valve inflow Doppler recording as the peak E velocity divided by the velocity time integral. The normal value for this index in children was 6.78 +/- 0.99 SV/sec and did not vary with age, weight, body surface area, or heart rate. Compared with normal subjects, both patients with aortic stenosis and patients with coarctation had increased left ventricular mass, but patients with aortic stenosis had decreased normalized peak filling rates (5.3 +/- 0.84 SV/sec, p < 0.01), while patients with coarctation had normal rates (6.79 +/- 0.98 SV/sec, p = 0.97). Compared with patients with aortic coarctation, patients with aortic stenosis had higher Doppler gradients. Thus the Doppler index of peak filling rate normalized to stroke volume is particularly useful in children because it is independent of heart rate, age, weight, and body surface area. Patients with coarctation may have normal peak filling rates normalized to stroke volume despite increased left ventricular mass because of milder obstruction or better coronary artery perfusion compared with that of patients with aortic stenosis.

Hemodynamic assessment of aortic stenosis

The decision to operate in patients with aortic stenosis is based on the presence of symptoms and hemodynamically significant valvular obstruction. The strengths and limitations of cardiac catheterization and Doppler echocardiography are compared, and the concept of "critical" aortic stenosis is discussed. The recommendation of aortic valve replacement must take into account the symptom status, the hemodynamic significance of the lesion, and the size and type of valve to be implanted.

The role of noncardiac disease in the development and precipitation of heart failure

The varying roles of a widely diverse group of noncardiac disorders on the heart, particularly their ability to induce heart failure, are explored. A general overview of the cardiac effects of volume and pressure overloading is followed by specific discussions of the roles of vascular, endocrine and metabolic, renal, gastrointestinal, central nervous system, hematologic, and other miscellaneous disorders (heat stroke, sepsis, immune-mediated disease, obesity, malnutrition, and pregnancy) in producing cardiac dysfunction and failure in companion animals. Pathogenetic and pathophysiologic mechanisms are emphasized.

Cardiac function after surgery for subaortic stenosis: non-invasive assessment of left ventricular performance

OBJECTIVE

To examine left ventricular function after surgical resection of subaortic stenosis during childhood.

DESIGN

Left ventricular performance was measured non-invasively in all patients who responded to an invitation for formal assessment.

SETTING

Outpatient study, tertiary referral centre.

PATIENTS

Twenty three (12 male and 11 female) patients (age range 3 to 31 years) of 43 consecutive patients with fixed subaortic stenosis undergoing surgical resection between 1975 and 1989 reattended for formal assessment 16 months to 15 years (median 4 years 4 months) after operation.

MAIN OUTCOME MEASURES

Left ventricular dimension, left ventricular wall thickness, left ventricular Doppler inflow velocities, and left ventricular diastolic pressure (measured from apexcardiograms). Results were compared with those in controls individually matched for age and sex.

RESULTS

All patients were symptom free. Left ventricular cavity dimensions were normal, as was the mean fractional shortening. Posterior wall thickness tended to be greater in the patients and there was a significant increase in septal thickness. Normalised peak rate of posterior wall thinning was significantly lower in the patients and the isovolumic relaxation time was significantly shorter. Doppler inflow velocity measurements showed that early diastolic mitral flow acceleration time was normal but deceleration time was significantly shorter in the patients. The ratio of mitral flow in early diastole (E) to E plus mitral flow in late diastole (A) was significantly higher in the patients and in two patients there was complete absence of A wave flow despite large A waves on the apexcardiogram.

CONCLUSIONS

Systolic function was well preserved in patients after operation for subaortic stenosis. A restrictive pattern of left ventricular filling was common, however, and presumably reflected a response to the chronic pressure load and to surgery in the paediatric heart.

Evaluation of left ventricular filling in dilated cardiomyopathy using digitized M-mode echocardiograms

Digital M-mode echocardiography describes a characteristic alteration in the pattern of left ventricular filling when a dilated cardiomyopathy is present. The peak rates of early diastolic dimension change (dD/dt and dD/dt/D) are uniformly reduced but remain unchanged in time of occurrence (time to dD/dt). The rapid filling period is slightly shortened compared to normals, but the %deltaD taking place during rapid filling is not different than normals. This pattern is distinct from characteristic alterations seen in other cardiac diseases that have preserved systolic performance. While M-mode indices of left ventricular filling may be altered by several factors, the most significant factors in dilated cardiomyopathy are the severity of systolic dysfunction and preload. Left-sided conduction delays and associated right ventricular enlargement have no demonstrable effect on very early portions of diastole, but the conduction delay does prolong the rapid filling period and reduce the extent of filling during this period. Combined use of digitized M-mode echocardiograms and Doppler analysis of transmitral flow may allow a more complete description of left ventricular filling in future studies.

Changes in left ventricular diastolic performance after aortic balloon valvuloplasty: acute and late effects

To evaluate acute and follow-up changes in left ventricular diastolic performance, simultaneous digital left ventriculography and micromanometry were performed in 49 patients undergoing aortic balloon valvuloplasty. All patients improved symptomatically after valvuloplasty, and 26 returned 6.3 +/- 1.5 months later for follow-up catheterization. Immediately after valvuloplasty, aortic valve area increased (before 0.5 +/- 0.2 versus after 0.8 +/- 0.2 cm2, p less than 0.01), cardiac output (before 4.3 +/- 1.2 versus after 4.4 +/- 1.3 liters/min) and ejection fraction (before 51 +/- 18% versus after 52 +/- 17%) did not change and diastolic indexes worsened, signified by a decrease in peak filling rate (before 247 +/- 80 versus after 226 +/- 78 ml/s, p less than 0.01) and increase in the time constant of isovolumetric relaxation (tau) (before 78 +/- 29 versus after 96 +/- 40 ms, p less than 0.01) and the modulus of chamber stiffness (before 0.107 +/- 0.071 versus after 0.141 +/- 0.083, p less than 0.01). At follow-up catheterization, 16 patients continued to have symptomatic improvement (group 1) and 10 had recurrence of symptoms (group 2). Aortic valve area, cardiac output and ejection fraction at follow-up catheterization in both groups were similar and unchanged from values before valvuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered systolic and diastolic function in children after "successful" repair of coarctation of the aorta

We investigated whether left ventricular (LV) structural or functional abnormalities persist in children on long-term follow-up after successful correction of coarctation of the aorta. Two-dimensional directed M-mode and Doppler echocardiographic examinations were performed in 11 such subjects and 22 age-matched control subjects. Digitized tracings were made from M-mode recordings of the LV and Doppler mitral valve inflow recordings to measure septal, posterior wall, and LV dimensions, LV mass, shortening fraction, peak shortening and lengthening velocities, diastolic filling time, peak E velocity, peak A velocity, and velocity time integrals. Despite group similarities in age, body size, and systolic blood pressure, greater fractional shortening (p = 0.0001), indexed peak shortening velocity (p less than 0.001), and greater LV mass index (p less than 0.05) were seen in the coarctation group in the face of lower LV wall stress (p = 0.0001). LV mass index correlated with the resting arm-leg gradient, which ranged from -4 to +10 mm Hg. The coarctation group had decreased early filling (p less than 0.006) with compensatory increased late diastolic filling (p less than 0.05). Diastolic filling abnormalities were prominent in the older coarctation subjects and were related to both systolic blood pressure (p less than 0.001) and LV mass index (p less than 0.01). Despite apparently successful repair of coarctation of the aorta, persistent alterations in both systolic and diastolic LV function and LV mass are present in children at long-term follow-up, which are related to the resting arm-leg gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulsed Doppler evaluation of right ventricular diastolic filling in children with pulmonary valve stenosis before and after balloon valvuloplasty

To assess right ventricular (RV) diastolic filling in children with pulmonary stenosis (PS), 14 patients (mean age 5.1 years) were examined immediately before and after pulmonary balloon valvuloplasty. Fourteen normal children (mean age 4.8 years) were also studied. From the tricuspid valve inflow Doppler study, the following measurements were made at peak inspiration: peak velocities at rapid filling (peak E) and during atrial contraction (peak A), ratio of peak E to peak A velocities, RV peak filling rate normalized for stroke volume, total area under the Doppler curve, percent of the total Doppler area occurring in the first third of diastole (0.33 area fraction), percent of the total area occurring under the E wave (E area fraction), percent of the total area occurring under the A wave (A area fraction) and the ratio of E area to A area. Before balloon valvuloplasty, the patients with PS had higher peak A velocity (0.64 +/- 0.28 vs 0.39 +/- 0.08 m/s), lower E/A velocity ratio (1.11 +/- 0.52 vs 1.76 +/- 0.45), lower 0.33 area fraction (0.34 +/- 0.14 vs 0.49 +/- 0.08), higher A area fraction (0.45 +/- 0.21 vs 0.27 +/- 0.09) and lower E/A area ratio (1.73 +/- 1.05 vs 2.96 +/- 1.14) than the normal subjects (p less than 0.01). In patients before and after balloon valvuloplasty, there was a significant difference in RV outflow gradient (71 +/- 35 vs 28 +/- 15 mm Hg), but there was no change in any Doppler index. Thus, patients with PS have abnormal diastolic filling with decreased filling in early diastole and increased filling during atrial contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Tolerance of the hypertrophic heart to ischemia. Studies in compensated and failing dog hearts with pressure overload hypertrophy

Tolerance of the canine heart to prolonged ischemic arrest was studied in 10 hearts from normal control dogs and 15 hearts from dogs with left ventricular hypertrophy (LVH); experiments were performed 1 year after banding the aorta in 8-week-old puppies. At 1 year, hemodynamic studies revealed decreased left ventricular (LV) fiber shortening and elevated end-diastolic pressure (EDP) in five dogs (group with LVH failure); 10 dogs exhibited normal shortening and normal EDP (group with LVH compensation). The left ventricle-to-body weight ratio (g/kg) was 4.4 +/- 0.8 in the control group of dogs, 7.7 +/- 1.0 in the group with LVH compensation, and 10 +/- 2.5 in the group with LVH failure. The tolerance to 60 minutes of global ischemia (37 degrees C) followed by 90 minutes of reperfusion was studied in an isolated blood-perfused heart apparatus (isovolumic left ventricle, coronary perfusion pressure of 100 mm Hg). In the baseline (preischemic) state, coronary blood flow, myocardial oxygen consumption, lactate extraction, and myocardial high-energy phosphate content were essentially equal in the three groups; with LV volume adjusted to produce a systolic pressure of 100 mm Hg, there were no significant differences in LVEDP among the three groups. During ischemia, the diastolic (asystolic) pressure increased from 11 +/- 3 to 28 +/- 16 mm Hg (p less than 0.05) in the group with LVH failure; however, it did not increase in the control or the LVH compensation groups. Myocardial ATP levels declined equally in all three groups. During early reperfusion, lactate washout was lowest in the group with LVH failure. By 90 minutes of reperfusion, there were no significant differences in coronary blood flow, myocardial oxygen consumption, lactate extraction, or high-energy phosphate levels. High diastolic pressure persisted at 90 minutes of reperfusion in the LVH failure group (EDP was 34 +/- 19 mm Hg); however, there was no significant change in EDP during reperfusion in the control or with LVH compensation groups. After 90 minutes of reperfusion, developed pressures in the control (54 +/- 9 mm Hg), the LVH compensation (49 +/- 18 mm Hg), and the LVH failure (67 +/- 17 mm Hg) groups were not significantly different. These data indicate that hearts with compensated LVH do not exhibit an impaired tolerance to ischemia.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of transmitral blood flow velocity by Doppler echocardiography in the evaluation of coronary artery disease

To determine the relation between presence and severity of coronary artery disease and diastolic filling abnormalities by Doppler echocardiography, recordings of transmitral inflow velocity were made at rest in 90 patients with coronary artery disease and 28 normals. At the time of the Doppler examination, 81 patients with coronary artery disease (90%) and 10 normals (36%) were treated with antianginal medications. No difference was found in the ratio between early (E) and late (A) diastolic filling velocity (E/A ratio) when comparing patients with greater than 70% obstruction of at least one coronary artery to age-matched normals, regardless of the presence or absence of wall motion abnormalities. The E/A ratio was 1.3 +/- 0.46 in coronary patients with normal wall motion, 1.2 +/- 0.47 in coronary patients with abnormal wall motion, and 1.3 +/- 0.53 in both samples of age-matched normals. Multivariate analysis of the relation between E/A ratio and other variables showed that heart rate (F = 24.46, p less than 0.00001) and age (F = 19.51, p less than 0.00001) were significant independent determinants of the E/A ratio, while the presence or severity of coronary artery disease, the presence of hypertension, the magnitude of wall motion abnormalities, and end-diastolic dimension by echocardiography were not. These data suggest that transmitral inflow velocity recordings by Doppler have limited value for the recognition of coronary artery disease, since the E/A ratio is profoundly influenced by other factors, such as heart rate and age.

Doppler echocardiographic analysis of diastolic left ventricular function in dialysis patients and its relation to intradialytic hypotension

Doppler echocardiography was used to evaluate left ventricular relaxation and filling in 20 patients on chronic maintenance hemodialysis. In comparison with 11 normal controls hemodialysed patients showed a marked prolongation of isovolumic relaxation period (83 +/- 23 ms vs 67 +/- 11 ms, P less than 0.01). Peak velocity of early diastolic filling was similar in both groups, but peak velocity of late ventricular filling due to atrial contraction was substantially increased in dialysis patients (66 +/- 23 cm/s vs 37 +/- 7 cm/s, P less than 0.01) and the ratio late to early peak velocity was significantly enlarged (0.97 +/- 0.35 vs 0.58 +/- 0.19, P less than 0.01). Although left ventricular mass index, as determined by Echo, was markedly increased in dialysis patients, no significant correlation was found between ventricular mass and indexes of diastolic function. When patients were divided into two groups on the basis of development of hypotension during dialysis clinical and echocardiographic characteristics were similar, although patients with dialysis hypotension (n = 9) were significantly older (53 +/- 9 years) than normotensive patients (n = 11, 42 +/- 14 years, P less than 0.05). Indexes of diastolic function showed a great overlap between the two groups, but ratio late to early peak velocity was significantly greater in patients with intradialytic hypotension (1.13 +/- 0.35 vs 0.83 +/- 0.32, P less than 0.05). It is concluded that dialysis patients exhibit significant alterations of left ventricular relaxation and diastolic filling as assessed by Doppler echocardiography which might be independent of left ventricular hypertrophy. Impaired diastolic function might contribute to intradialytic hypotension.

Differentiation of restrictive cardiomyopathy from pericardial constriction: assessment of diastolic function by radionuclide angiography

Diastolic filling variables were studied in 12 patients with the hemodynamic features of constriction, of whom 5 had restrictive cardiomyopathy, 5 had pericardial constriction and 2 had combined pericardial constriction and restrictive cardiomyopathy. The values were compared with those in 10 normal subjects of comparable age. The filling fractions between 10% and 70% of the diastolic time interval were greater in patients with pericardial constriction than in those with restrictive cardiomyopathy (p less than 0.01 between 20% and 50%, p less than 0.05 at 10%, 60% and 70%), with no overlap. The filling fractions in patients with pericardial constriction were also greater than those in normal subjects between 10% and 60% of the diastolic time interval. The filling fraction was lower in patients with restrictive cardiomyopathy than in normal subjects at 40% of the diastolic time interval (p less than 0.05). The time to peak filling rate in patients with pericardial constriction was shorter (110 +/- 14 ms) than in those with restrictive cardiomyopathy (195 +/- 45 ms, p less than 0.01) or in normal subjects (173 +/- 32 ms, p less than 0.01). The percent of atrial contribution to left ventricular filling was higher in those with restrictive cardiomyopathy (45 +/- 17%) than in those with pericardial constriction (21 +/- 6%, p less than 0.05) or in normal subjects (24 +/- 9%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of diastolic function of the heart: background and current applications of Doppler echocardiography. Part II. Clinical studies

Evaluation of diastolic filling of the heart has been difficult because of its complexity and the numerous interrelated contributing factors. Previous determinations have depended on high-fidelity, invasive measurements of instantaneous pressure, volume, mass, and wall stress, which could not be done on a routine clinical basis. With the advent of Doppler echocardiography, intracardiac blood flow velocities can now be noninvasively assessed. For application of this technique to evaluation of diastolic function in patients with heart disease, it is necessary to understand what the Doppler-derived variables represent. It is also necessary to know how they are affected by changes in loading conditions and changes in myocardial relaxation. In this review, we provide an interpretation of the mitral valve, tricuspid valve, and systemic and pulmonary venous inflow velocities in the normal patient and in various disease states.

Doppler echocardiographic evaluation of left ventricular diastolic filling in isolated valvular aortic stenosis

Doppler echocardiography was used to study left ventricular (LV) diastolic filling in 49 adults with isolated aortic stenosis (AS), selected from 155 consecutive patients with AS by excluding coexisting mitral disease (n = 41) and/or significant aortic regurgitation (n = 80). There were no differences between patients with AS and age-matched normal subjects for early diastolic filling (E) velocity (68 +/- 17 vs 67 +/- 13 cm/s), late diastolic filling (A) velocity (79 +/- 25 vs 67 +/- 21 cm/s), E/A ratio (1.00 +/- 0.78 vs 1.06 +/- 0.32) or early diastolic deceleration slope (264 +/- 151 vs 319 +/- 137 cm/s2, differences not significant for all). There was no correlation between any LV filling parameter and AS severity, but late diastolic filling velocity was higher in patients with AS who had LV hypertrophy (n = 33) vs those who did not (n = 16) (86 +/- 23 vs 65 +/- 26 cm/s, p less than 0.01). In the patients with AS and systolic dysfunction (LV ejection fraction less than 50%) (n = 6), early diastolic filling velocity was higher (88 +/- 20 vs 65 +/- 15 cm/s, p less than 0.01), late diastolic filling velocity lower (53 +/- 23 vs 83 +/- 23 cm/s, p less than 0.01), E/A ratio higher (2.20 +/- 1.80 vs 0.84 +/- 0.28, p less than 0.01), deceleration slope steeper (439 +/- 230 vs 240 +/- 121 cm/s2, p = 0.02) and LV end-diastolic pressure higher (23 +/- 9 vs 10 +/- 6 mm Hg, p less than 0.01) than in patients with AS and normal systolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulsed Doppler assessment of left ventricular diastolic filling in children with left ventricular outflow obstruction before and after balloon angioplasty

To assess left ventricular (LV) diastolic filling in children with pressure overload hypertrophy, 12 patients with LV outflow obstruction (7 with aortic valve stenosis and 5 with aortic coarctation) and 12 healthy, age-matched control subjects were examined. Each child underwent M-mode echocardiography and pulsed Doppler examination of the LV inflow. The patients with LV outflow obstruction had cardiac catheterization and balloon angioplasty. Their echo/Doppler examinations were performed in the catheterization laboratory before and immediately after balloon angioplasty. From the M-mode echocardiogram, the LV cavity dimensions and wall thicknesses, LV mass and shortening fraction were measured. The following measurements were made from the Doppler recording: peak velocities at rapid ventricular filling (peak E) and during atrial contraction (peak A), ratio of peak E to peak A velocities, total area under the Doppler curve, percent of the total Doppler area occurring in the first one-third of diastole (0.33 area fraction), percent of the total area occurring under the E wave (E area fraction), percent of the total area occurring under the A wave (A area fraction) and the ratio of E area to A area.(ABSTRACT TRUNCATED AT 250 WORDS)

The physiological basis of left ventricular diastolic dysfunction

Overall cardiac pump function requires adequate ventricular diastolic filling as well as normal systolic ejection. Abnormalities of the rate or extent of myocardial relaxation (diastolic dysfunction) have been described in a large variety of clinical conditions, including hypertrophy, ischemia, and after cardiac surgery. Diastolic and systolic dysfunction can be readily distinguished by analysis of pressure volume loops and utilization of echocardiography or nuclear cardiology gated blood pool scans. The mechanisms by which diastolic dysfunction can occur may be structural (hypertrophy, fibrosis) or dynamic (hypoxia, ischemia, alteration of diastolic cytosolic calcium levels). Hypertrophied myocardium is particularly susceptible to diastolic dysfunction by virtue of both structural changes (increased LV mass and interstitial fibrosis) and greater susceptibility to develop impaired myocardial relaxation during hypoxia or ischemia than nonhypertrophied myocardium.

Postextrasystolic potentiation worsens fast filling of the hypertrophied left ventricle in aortic stenosis and hypertrophic cardiomyopathy

Impaired left ventricular (LV) filling in aortic stenosis (AS) and in hypertrophic cardiomyopathy (HCM) is caused by slow LV pressure decay, which could be explained by depressed inactivation of hypertrophied myocardium. Postextrasystolic potentiation (PESP), which increases activator calcium, could lead to further deterioration of LV relaxation. The influence of PESP on LV filling dynamics was, therefore, investigated in normal controls and in patients with LV hypertrophy caused by AS or by HCM. LV hemodynamics and LV hemodynamic relaxation indexes were determined during normal sinus rhythm (NSR) and after PESP. LV pressures were recorded by micromanometer tip catheters (controls, n = 10; AS, n = 17; HCM, n = 11). Simultaneous mitral flow Doppler echocardiograms were obtained in patients with LV hypertrophy (AS, n = 8, HCM, n = 5). Despite significant increases of LV dP/dtmax after PESP in all three study groups, PESP affected LV hemodynamic relaxation indexes differently. The time constant of LV pressure decay (TPB) derived from exponential curve fits with nonzero asymptote pressure remained unaltered after PESP in normal controls, rose from 62 +/- 17 to 74 +/- 21 msec (p less than 0.02) in patients with AS, and rose from 74 +/- 18 to 84 +/- 19 msec (p less than 0.02) in patients with HCM. Early diastolic LV pressure decay was measured by phi (phase of the first harmonic of a Fourier transform applied to the diastolic LV pressure waves) and by t (time interval from LV dP/dtmin to LV minimum diastolic pressure). After PESP, phi remained unaltered in normal controls but decreased in AS from 42.8 +/- 19.1 degrees to 24.0 +/- 28.8 degrees (p less than 0.001) and in HCM from 39.7 +/- 15.4 degrees to 26.9 +/- 15.7 degrees (p less than 0.001). Similarly, t was unchanged after PESP in normal controls but prolonged in AS from 146 +/- 48 to 205 +/- 86 msec (p less than 0.001) and in HCM from 168 +/- 40 to 208 +/- 53 msec (p less than 0.02).(ABSTRACT TRUNCATED AT 400 WORDS)

Diastolic function in patients with aortic stenosis: influence of left ventricular load reduction

Pressure overload hypertrophy of the left ventricle due to aortic stenosis is associated with abnormalities of left ventricular isovolumic relaxation and early diastolic filling. The relative contribution of the hemodynamic load on the left ventricle to the impairment of diastolic function observed in this disorder remains poorly understood. To study this relation, the vasodilator nitroprusside was administered to eight patients with aortic stenosis and normal systolic function. The effect of a short-term reduction in left ventricular preload and afterload on left ventricular isovolumic relaxation and early diastolic filling was assessed by analysis of simultaneous micromanometer left ventricular pressure and radionuclide angiographic volume measurements. At baseline, left ventricular systolic and end-diastolic pressures were markedly elevated, and associated with prolongation of the time constant of left ventricular relaxation and depression of the left ventricular peak filling rate. Infusion of nitroprusside resulted in reduction of left ventricular systolic (204 +/- 31 to 176 +/- 31 mm Hg, p less than 0.05) and end-diastolic (31 +/- 8 to 18 +/- 6 mm Hg, p less than 0.05) pressures, with no associated improvement in time constant of left ventricular pressure decay (T) (68 +/- 25 to 80 +/- 37 ms, p = NS), T 1/2 (34 +/- 8 to 34 +/- 14 ms, p = NS), left ventricular peak filling rate (2.3 +/- 0.5 to 2.3 +/- 0.8 end-diastolic volume/s, p = NS) or time to left ventricular peak filling rate (150 +/- 50 to 144 +/- 37 ms, p = NS).(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)

Decreased early diastolic function after indomethacin administration in premature infants

The effect of indomethacin on systolic and diastolic cardiac function was assessed in 15 premature infants. Seven infants (group 1) received indomethacin to treat a clinically significant patent ductus arteriosus (PDA), and eight infants (group 2) received indomethacin prophylactically at 24 hours of age because of their high risk for PDA. Diastolic cardiac function was assessed using instantaneous rates of change of left ventricular (LV) cavity dimension, derived from M-mode echocardiography. The maximum velocity of lengthening of the LV cavity dimension, an index of early diastolic function, fell from 63 +/- 19 mm/sec before indomethacin to 48 +/- 16 mm/sec 1 hour after indomethacin in group 1 (P less than 0.01), with the ductus still patent and the LV chamber still dilated, and also decreased in group 2, from 52 +/- 7 mm/sec to 38 +/- 6 mm/sec (P less than 0.01). This index, when normalized for loading conditions, was decreased 1 hour after indomethacin at 12 +/- 2 sec-1 and 12 +/- 1 sec-1 for groups 1 and 2, respectively, compared with values before indomethacin of 15 +/- 3 sec-1 and 15 +/- 2 sec-1. There was no effect of indomethacin on the indices of systolic function. We conclude that indomethacin decreases early diastolic function in premature infants.

Diastolic blood pressure as a determinant of Doppler left ventricular filling indexes in normotensive adolescents

Alterations in left ventricular filling can occur with aging and in patients with hypertension, ischemic heart disease, congestive and hypertrophic cardiomyopathy and congenital heart disease. This study examines the effects of blood pressure on left ventricular diastolic filling indexes measured by Doppler ultrasound technique in 47 young normotensive adolescents (mean age 13 years). Left ventricular filling was assessed by Doppler peak early and late diastolic transmitral flow velocities, early and late diastolic flow velocity integrals and early diastolic deceleration. Systolic blood pressure did not correlate with any of the Doppler filling indexes, although it was related to echocardiographic left ventricular mass (r = 0.44, p less than 0.005). Diastolic blood pressure did not correlate with left ventricular mass; however, it was inversely related to peak early diastolic flow velocity (r = -0.44, p less than 0.005), early diastolic flow velocity integral (r = -0.40, p less than 0.01) and early diastolic deceleration (r = -0.32, p less than 0.05). The ratio of late to early peak filling (A/E) was directly related to diastolic blood pressure (r = 0.48, p less than 0.001). Examination of electrocardiograms showed that there was a stronger correlation between A/E ratio and diastolic blood pressure (r = 0.63) in 22 subjects with bimodal P waves in lead V1 than in subjects with unimodal P waves (r = 0.45).(ABSTRACT TRUNCATED AT 250 WORDS)

Preload dependence of Doppler-derived indexes of left ventricular diastolic function in humans

To determine the effect of filling pressure on the pattern of left ventricular filling in humans, the mitral flow velocity profile was measured by pulsed wave Doppler echocardiography during right and left heart catheterization in 11 patients before and during nitroglycerin infusion. Nitroglycerin reduced mean arterial pressure from 90 +/- 9 to 80 +/- 11 mm Hg (p less than 0.001) and mean pulmonary capillary wedge pressure from 9 +/- 4 to 4 +/- 2 mm Hg (p less than 0.001). Cardiac output fell from 6.6 +/- 1.5 to 5.5 +/- 1.4 liters/min (p less than 0.001) and heart rate increased from 60 +/- 13 to 65 +/- 14 beats/min (p less than 0.002). The time constant of isovolumic relaxation (TI.) decreased from 51 +/- 9 to 46 +/- 8 ms (p less than 0.01), indicating faster left ventricular relaxation. Nitroglycerin altered the Doppler characteristics of the early filling (E) wave but not those of the atrial contraction (A) wave. Peak velocity of the E wave decreased from 56 +/- 14 to 44 +/- 9 cm/s (p less than 0.001), peak velocity of the A wave did not change and the ratio of peak velocities of the E and A waves decreased from 0.97 +/- 0.33 to 0.77 +/- 0.20 (p less than 0.02). The deceleration of the E wave decreased from 289 +/- 138 to 186 +/- 71 cm/s2 (p less than 0.02). The ratio of velocity-time integral of the A wave to total velocity-time integral (that is, contribution of atrial contraction to total filling) increased from 0.31 +/- 0.09 to 0.36 +/- 0.08 (p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)