Isovolumic relaxation period in man

Comparison Between Invasive and Noninvasive Methods to Estimate Subendocardial Oxygen Supply and Demand Imbalance

Background

Estimation of the balance between subendocardial oxygen supply and demand could be a useful parameter to assess the risk of myocardial ischemia. Evaluation of the subendocardial viability ratio (SEVR, also known as Buckberg index) by invasive recording of left ventricular and aortic pressure curves represents a valid method to estimate the degree of myocardial perfusion relative to left ventricular workload. However, routine clinical use of this parameter requires its noninvasive estimation and the demonstration of its reliability.

Methods and Results

Arterial applanation tonometry allows a noninvasive estimation of SEVR as the ratio of the areas directly beneath the central aortic pressure curves obtained during diastole (myocardial oxygen supply) and during systole (myocardial oxygen demand). However, this “traditional” method does not account for the intra‐ventricular diastolic pressure and proper allocation to systole and diastole of left ventricular isometric contraction and relaxation, respectively, resulting in an overestimation of the SEVR values. These issues are considered in the novel method for SEVR assessment tested in this study. SEVR values estimated with carotid tonometry by "traditional” and "new” method were compared with those evaluated invasively by cardiac catheterization. The “traditional” method provided significantly higher SEVR values than the reference invasive SEVR: average of differences±SD= 44±11% (limits of agreement: 23% – 65%). The noninvasive “new” method showed a much better agreement with the invasive determination of SEVR: average of differences±SD= 0±8% (limits of agreement: ‐15% to 16%).

Conclusions

Carotid applanation tonometry provides valid noninvasive SEVR values only when all the main factors determining myocardial supply and demand flow are considered.

Effect of Levosimendan on Diastolic Function in Patients Undergoing Coronary Artery Bypass Grafting: A Comparative Study

PURPOSE

To compare the efficacy of levosimendan with nitroglycerin in patients with isolated diastolic dysfunction undergoing coronary artery bypass grafting.

PROCEDURE

Thirty patients with isolated diastolic dysfunction undergoing on-pump coronary artery bypass grafting were randomized into 2 groups receiving levosimendan or nitroglycerin infusion. The infusion was started before sternotomy and continued in the postoperative period. Perioperatively, diastolic function was serially evaluated at 3 different time points using echocardiography. N-terminal fragment of pro-B-natriuretic peptide (NT-proBNP) levels were measured in both the groups.

RESULTS

There was a significant improvement in diastolic function as measured by isovolumic relaxation time (P = 0.0001, P = 0.001) and deceleration time (P = 0.0001, P = 0.0001) in the levosimendan group from the baseline in patients with impaired relaxation. Similarly, tissue Doppler imaging also revealed an improvement from the baseline in patients with a pseudonormal pattern (P = 0.018, P = 0.001). Furthermore, there was a significant improvement in the above parameters when compared with the nitroglycerin group. The NT-proBNP levels also demonstrated a similar pattern between the 2 groups (P = 0.03, P = 0.02) when levosimendan was compared with nitroglycerin in patients with a pseudonormal pattern on echocardiography.

CONCLUSIONS

Levosimendan is superior to nitroglycerin in improving diastolic function irrespective of coronary revascularization.

Cardiac ventricular diastolic and systolic duration in children with heart failure secondary to idiopathic dilated cardiomyopathy

Systole and diastole are the fundamental periods of the cardiac cycle, yet little emphasis has been placed on their relative duration when evaluating heart failure. Cardiac intervals are used to assess ventricular function, but the relative duration of systole and diastole for defining function have not been evaluated. We hypothesized that in heart failure, systole is prolonged and diastole shortened. We defined systole and diastole in 16 children with idiopathic dilated cardiomyopathy and in 16 normal controls, matched for age and gender, using the mitral regurgitant (MR) and tricuspid regurgitant (TR) flow duration. The systole and diastole durations (expressed as a fraction of the cardiac cycle) were correlated with heart rate and age and compared between groups. The subjects were compared with gender- and age-matched controls (9.98 +/- 6.1 vs 9.88 +/- 6.08 years, p = NS). The 2 groups had similar heart rates (104 +/- 31 vs 92 +/- 34 beats/min, p = NS). The systole duration was not significantly different when measured by MR versus TR duration (0.60 +/- 0.10 vs 0.57 +/- 0.11 of the cardiac cycle, respectively, p = NS). Systole was prolonged in subjects compared with controls (0.60 +/- 0.1 vs 0.42 +/- 0.08, respectively, using MR duration, p < 0.0001 and 0.57 +/- 0.11 vs 0.41 +/- 0.07, respectively, using TR duration, p = 0.0008). The systolic/diastolic ratio was 0.77 +/- 0.24 in the controls versus 1.57 +/- 0.98 in the patients with idiopathic dilated cardiomyopathy using the TR duration (p < 0.005) and 1.67 +/- 0.68 using the MR duration (p < 0.0001). The systole duration correlated with heart rate in subjects (r = 0.79, p = 0.0003) and controls (r = 0.69, p = 0.003). In conclusion, systole is significantly prolonged and diastole correspondingly shortened in heart failure. Reversal of the normal systolic/diastolic ratio may compromise cardiac filling and function. The systole and diastole duration are easily measured using routine Doppler flow, enhancing assessment of cardiac function in children.

Effects of afterload increase on systolic and diastolic functions of the myocardium after myocardial infarction

The evaluation of noninfarcted zone function after myocardial infarction by the use of noninvasive methods is very important. The authors speculated that phenylephrine, which increases systemic vascular resistance and blood pressure and has no effect on central ischemic and border-zone myocardium but does have an effect on remote myocardium, could be used as a stress agent as information is gathered about the functional capacity of the left ventricle and the status of coronary arteries in patients with recent myocardial infarction. Forty-six patients with recent myocardial infarction (5 women, 41 men; mean age: 53.6 +/-9.3 years) and 15 individuals with normal findings from coronary angiography and ventriculography (9 women and 6 men; mean age: 39.0 +/-11.2 years) were included in the study. The study was performed on the 4th or 5th day of the myocardial infarction. Preejection period/left ventricular ejection time (PEP/LVET), diastolic mitral flow velocity, isovolumic relaxation time (IVRT), and deceleration time (DT), were measured before and after the phenylephrine infusion, with M-mode, pulse wave, and continuous-wave echocardiography. After pressor stress with phenylephrine infusion, all the parameters were measured again. Coronary angiography and ventriculography were performed on all the patients on the 7th to 10th day of the myocardial infarction. All the patients were grouped according to their ejection fraction and the number of involved coronary arteries. The increase in the PEP/LVET ratio in Group 1 (left ventricle ejection fraction [EF] below 40%) and multivessel coronary artery lesion group was significant (p<0.01). PEP/LVET ratio decreased significantly in both Group C (patients with normal-appearing coronary arteries and ventriculographies) and the single-vessel coronary disease group. Although the early diastole flow/atrial systole flow (E/A) ratio increased significantly in the 3 groups, the 0.5 and more increase in E/A ratio had high sensitivity (86%) and specificity (80%) in differentiating the low EF group. The 0.5 and more increase in E/A ratio had 65% sensitivity and 69% specificity in differentiating the multivessel coronary stenosis group. A deceleration time of 130 msec and below in basal conditions had a high sensitivity (86%) and specificity (92%) for detecting the group in which EF was below 40%. After phenylephrine infusion, the shortening of IVRT was significant in Group 1 (p<0.01). Phenylephrine, which has been shown to be an alpha-1 receptor agonist in low doses and effective only on remote myocardial function, may be given with low complication rates in the early postinfarction period. The increase in PEP/LVET ratio, 0.5 and more increase in E/A ratio, and shortening of DT and IVRT after phenylephrine infusion may be indicators of low LV functional capacity and widespread coronary artery disease. This test may suggest performance of early invasive detection of coronary artery disease and early revascularization. This study may also be interesting from a pathophysiological point of view.

Effects of valve dysfunction on Doppler Tei index

BACKGROUND

Recently proposed Doppler Tei index, defined as the sum of isovolumic contraction time or mitral valve closure to aortic valve opening time and isovolumic relaxation time or aortic valve closure to mitral valve opening time divided by ejection time, is a simple measure which enables noninvasive estimation of combined systolic and diastolic function and prediction of patients' prognosis. However, effects of valve dysfunction on Tei index have not been investigated. This study was designed to compare Tei index before and after surgical valve replacement or repair to evaluate effects of valve dysfunction on Tei index.

METHODS

Participants consisted of 76 consecutive patients with aortic or mitral valve surgery (26 patients with aortic stenosis [AS], 16 with aortic regurgitation, 17 with mitral stenosis, and 17 with mitral regurgitation). Doppler Tei index was evaluated before and after the surgery by obtaining (a-b)/b, where a is the interval between the cessation and onset of Doppler mitral filling flow and b is the aortic flow ejection time.

RESULTS

Tei index significantly increased after surgery in patients with AS (0.38 +/- 0.07 to 0.49 +/- 0.06, P <.001), aortic regurgitation (0.60 +/- 0.20 to 0.70 +/- 0.18, P <.01), mitral stenosis (0.34 +/- 0.03 to 0.39 +/- 0.04, P <.01), and decreased with no significance in mitral regurgitation (0.50 +/- 0.03 to 0.46 +/- 0.03). Percent change in Tei index after valve surgery was maximal in patients with AS (27 +/- 6 vs 17 +/- 2 vs 16 +/- 6 vs -9% +/- 6%, AS vs aortic regurgitation vs mitral stenosis vs mitral regurgitation, P <.001).

CONCLUSION

Tei index significantly changes after valve surgery especially in patients with AS. Considerations for the effects of valve dysfunction on Tei index are required for its application to evaluate ventricular function in patients with valve disease.

Reversal of intraventricular flow propagation during isovolumic relaxation: A marker of anterior wall dysfunction

BACKGROUND

Myocardial infarction induces left ventricular (LV) wall motion abnormalities during isovolumic relaxation (IVR) and may potentially alter intraventricular flow during this period. This study evaluated whether 2-dimensional color Doppler measurements of intraventricular flow during IVR were able to identify LV dysfunction caused by coronary artery disease.

METHODS

Patients with single-vessel coronary artery disease and posterior wall infarction (21 patients) or anterior wall infarction (27 patients) were included. Eighteen healthy persons served as a control group. LV function was examined by 2-dimensional echocardiography, 2-dimensional color Doppler, and pulsed Doppler techniques.

RESULTS

All normal persons (23.6 +/- 10.9 cm/s) and patients with posterior infarction (19.6 +/- 9.3 cm/s) had flow propagation towards LV apex during IVR. Patients with anterior wall infarction had reversed flow direction (-12.2 +/- 8.7 cm/s, P <.001). The echocardiographic wall motion score index of the 4 apical segments correlated well with flow velocities (r = -0.78, P <.001).

CONCLUSION

Reversed flow propagation during IVR may become a sensitive clinical marker of regional ischemia.

Effect of positive end-expiratory pressure on left and right ventricular diastolic filling assessed by transoesophageal Doppler echocardiography

The effect of positive end-expiratory pressure (PEEP) on left and right ventricular diastolic filling dynamics was assessed by transmitral and transtricuspid flow patterns. Using transoesophageal Doppler echocardiography in fourteen ASA physical status 1 female patients, the following measurements were performed at baseline (0 cm H2O PEEP) and at 5, 10, 15, and 20 cm H2O PEEP: 1. peak velocity of early filling (peak E velocity), 2. peak velocity of atrial contraction (peak A velocity), 3. the ratio of the peak E to A velocity (peak E/A velocity ratio), 4. isovolumic relaxation time (IRT), 5. acceleration half-time (AHT), 6. deceleration half-time (DHT) of early filling, and 7. end-diastolic and end-systolic areas of both ventricles. Increasing PEEP progressively deceased peak E velocity of both ventricles. In contrast, peak A velocity did not change and the peak E/A velocity ratio decreased significantly with PEEP. IRT and AHTs remained unchanged, but DHTs of both ventricles increased following PEEP. End-diastolic and end-systolic areas of both ventricles decreased gradually and significantly with PEEP. It is concluded that PEEP was associated with decreased preload as well as reduced compliance of both ventricles, which was considered to contribute to the changes in diastolic ventricular filling.

Class Ia antiarrhythmic drug cibenzoline: a new approach to the medical treatment of hypertrophic obstructive cardiomyopathy

BACKGROUND

The class Ia antiarrhythmic drug disopyramide relieves the outflow tract obstruction of hypertrophic obstructive cardiomyopathy (HOCM). Disopyramide, however, has several adverse effects, such as dysuria and thirst, resulting from its anticholinergic activity. A new class Ia antiarrhythmic drug, cibenzoline, has little anticholinergic activity. The aim of this study is to elucidate whether cibenzoline attenuates left ventricular pressure gradient (LVPG) in patients with HOCM.

METHODS AND RESULTS

Ten patients with HOCM (mean age, 59+/-12 years) participated in this study. LVPG and left ventricular functions were measured before and 2 hours after administration of a single oral dose of 150 or 200 mg cibenzoline. LVPG decreased from 123+/-60 to 39+/-33 mm Hg (P=.0026). The E/A ratio in transmitral Doppler flow increased from 1.20+/-0.84 to 2.00+/-1.72 (P=.029). Isovolumic relaxation time increased from 73+/-16 to 101+/-23 ms (P=.0026). Left ventricular diastolic dimension remained unchanged, but left ventricular systolic dimension enlarged significantly, from 21.6+/-2.4 to 26.2+/-3.3 mm (P=.0004). Fractional shortening decreased from 47.6+/-6.1% to 34.6+/-8.8% (P=.0007). Left ventricular ejection time index decreased significantly, and preejection period index increased in all the patients. Decreased LVPG remained maintained even in the long-term treatment with cibenzoline. Conclusions These results indicate that cibenzoline can markedly attenuate LVPG in patients with HOCM. A decrease in myocardial contractility seems to be closely related to a marked decrease in LVPG.

Clinical application of pulsed Doppler tissue imaging for assessing abnormal left ventricular relaxation

Conventional assessment of left ventricular (LV) relaxation by calculating the time constant of LV pressure decay during the isovolumic diastole requires an invasive approach. Conversely, noninvasive parameters obtained by measuring isovolumic relaxation time and transmitral flow velocity often give inaccurate information. Using LV pressure curve, pulsed Doppler echocardiography, and pulsed Doppler tissue imaging in 38 patients with heart disease and 12 control subjects, we calculated the time constant and recorded transmitral flow velocity and motion velocities at the endocardial portions of the ventricular septum and LV posterior wall. Compared with the controls, patients exhibited a prolonged time constant, a decreased peak early diastolic velocity of the LV posterior wall, and a prolonged time interval from the second heart sound to the peak of the early diastolic wave. The time constant correlated well with the isovolumic relaxation time and various parameters calculated from the transmitral flow velocity, except in patients with elevated LV end-diastolic pressure. In all subjects, the time constant correlated negatively with the peak early diastolic velocity of the posterior wall and positively with the time from the second heart sound to the peak of the early diastolic wave. Thus, early diastolic parameters derived from the motion velocity of the LV posterior wall by pulsed Doppler tissue imaging were closely related to the time constant. This technique may allow noninvasive evaluation of abnormal LV relaxation in patients with various heart diseases.

Noninvasive assessment of the ventricular relaxation time constant (tau) in humans by Doppler echocardiography

BACKGROUND

The time constant of ventricular relaxation (tau) is a quantitative measure of diastolic performance requiring intraventricular pressure recording. This study validates in humans an equation relating tau to left ventricular pressure at peak -dP/dt (P0), pressure at mitral valve opening (PMV), and isovolumic relaxation time (IVRTinv). The clinically obtainable parameters peak systolic blood pressure (Ps), mean left atrial pressure (PLA), and Doppler-derived IVRT (IVRTDopp) are then substituted into this equation to obtain tau Dopp noninvasively.

METHODS AND RESULTS

High-fidelity left atrial and left ventricular pressure recordings with simultaneous Doppler by transesophageal echocardiography were obtained from 11 patients during cardiac surgery. Direct curve fitting to the left ventricular pressure trace by Levenberg-Marquardt regression assuming a zero asymptote generated tau LM, the "gold standard" against which tau calc (IVRT inv/[ln(P0)-ln(PMV)]) and tau Dopp [IVRTDopp/[ln(Ps)-ln(PLA)]] were compared. For 123 cycles analyzed in 18 hemodynamic states, mean tau LM was 53.8 +/- 12.9 ms. tau calc (51.5 +/- 11 ms) correlated closely with this standard (r = .87, SEE = 5.5 ms). Noninvasive tau Dopp (43.8 +/- 11 ms) underestimated tau LM but exhibited close linear correlation (n = 88, r = .75, SEE = 7.5 ms). Substituting PLA = 10 mm Hg into the equation yielded tau 10 (48.7 +/- 15 ms), which also closely correlated with the standard (r = .62, SEE = 11.6 ms).

CONCLUSIONS

The previously obtained analytical expression relating IVRT, invasive pressures, and tau is valid in humans. Furthermore, a more clinically obtainable, noninvasive method of obtaining tau also closely predicts this important measure of diastolic function.

Evaluation of left ventricular relaxation using the continuous-wave Doppler velocity profile of aortic regurgitation: noninvasive measurement of left ventricular negative dP/dt and time constant

BACKGROUND

The maximal negative dP/dt [max (-)dP/dt] and time constant (T) are useful indices for evaluating left ventricular (LV) relaxation, but they require invasive procedures.

HYPOTHESIS

The purpose of this study was to obtain max (-)dP/dt and T using the continuous-wave Doppler aortic regurgitation velocity curve (AR-CW) noninvasively. Using the Bernoulli equation, the AR-CW allows accurate determination of the pressure gradients (PG) between the aorta and the left ventricle.

METHODS

In 10 patients with trivial to mild AR, the rising segment of the AR-CW reflecting LV pressure decrease was digitized with the cardiac image analysis system. Transpulmonary contrast-enhanced Doppler echocardiography was used in three patients to obtain intense velocity envelope. The PG curve and the firs derivative curve were reconstructed and the maximal point of the first derivative curve, which is consistent with max(-)dP/dt, was termed as maximal rate of pressure fall (maxRPF). As T (calculated according to the method of Weiss) can be obtained from T=Pm/max(-)dP/dt [Pm: LV pressure at the phase of max(-)dP/dt], we calculated T from Pm/maxRPF (Pm=dicrotic notch pressure-4Vm2) (Vm: AR velocity at the phase of maxRPF).

RESULTS

The Doppler-derived maxRPF and T (TD) approximated the catheter-derived max(-)dP/dt and T (y = 0.85x + 245, r = 0.97, p < 0.001, y = 0.79x + 4, r = 0.87, p < 0.001). In addition, dobutamine echocardiography was performed in nine patients showing increased maxRPF and decreased TD, indicating improvement of LV relaxation.

CONCLUSION

These Doppler-derived new indices are sufficiently useful to evaluate LV relaxation noninvasively.

Cardiovascular effect of oral calcium supplementation: echocardiographic study in patients with essential hypertension

Oral calcium (Ca) supplementation mildly reduces blood pressure. The authors studied the effects of Ca supplementation on the cardiovascular system in patients with mild to moderate essential hypertension. Twelve patients aged forty-nine to seventy years (7 men and 5 women, mean age with 60.3 +/- 7.2 years) participated. The investigators orally administered Ca (1.0 g/day for one week) under hospitalization, adding to a dietary intake of Ca (0.6 g/day). Left ventricular function and systemic arterial compliance were evaluated by M-mode and pulsed Doppler echocardiographies before and after seven days of Ca supplementation. Left ventricular contractility and afterload were not changed. Preload indicated by end-diastolic volume was significantly decreased after Ca supplementation (109.6 +/- 8.5 vs 107.3 +/- 8.2 mL, P < 0.05). Myocardial relaxation evaluated by IIa-mitral valve opening time (87.7 +/- 6.7 vs 82.1 +/- 6.2 ms, P < 0.01) and maximum descending rate of the left ventricular posterior wall (10.6 +/- 1.0 vs 12.4 +/- 1.0 cm/s, P < 0.01), and atrioventricular net compliance assessed by the descending slope of rapid filling flow in the left ventricular inflow tract (2.63 +/- 0.24 vs 2.26 +/- 0.17 m/s2, P <0.05), as well as systemic arterial compliance (2.05 +/- 0.20 vs 2.73 +/- 0.26 mL/mmHg, P < 0.01) were significantly improved by Ca supplementation. Oral Ca supplementation improved the disturbed left ventricular diastolic function and systemic arterial compliance.

Left ventricular systolic and diastolic function, and exercise capacity six to eight weeks after acute myocardial infarction. The DEFIANT Study Group. Doppler Flow and Echocardiography in Functional Cardiac Insufficiency: Assessment of Nisoldipine Therapy

Echocardiographic and Doppler-derived measurements of left ventricular (LV) function at rest were examined as predictors of maximal bicycle exercise capacity in a homogeneous group of 115 patients with mild to moderate LV dysfunction (ejection fraction 22 to 56%, median 43%) participating in the DEFIANT study of nisoldipine after acute myocardial infarction. Although the relations were not exact, peak exercise work load 7 weeks after infarction correlated with measurements of diastolic LV function at rest. Exercise work load was inversely related to peak late diastolic transmitral blood flow velocity (A wave) (slope -86.6; 95% confidence interval -120.9 to -52.2) and directly to the E/A ratio (slope 20.5; 95% confidence interval 6.0 to 35.1). The relations between exercise work load and peak late diastolic flow velocity remained significant after correction for age, sex, heart rate at rest, and use of beta-blocking drugs or nisoldipine. There was no relation between peak exercise work load and peak early diastolic transmitral flow velocity (E wave), isovolumic relaxation period or deceleration time. Measurements of systolic LV function (LV end-diastolic and end-systolic volumes, and ejection fraction, stroke volume and cardiac index) were also not significant as predictors of exercise capacity.

New approaches to noninvasive assessment of pulmonary artery pressure

Direct measurement of pulmonary artery pressure (PAP) was performed in 36 patients; right ventricular (RV) isovolumic relaxation time (IRT) and RV systolic output acceleration time (AcT) values were assessed by pulsed Doppler and 2-M echocardiography. There was a fairly good correlation between RV IRT and systolic PAP (r = 0.898; SEE = 7.8 mmHg) and a somewhat weaker one between RV AcT and systolic PAP (r = -0.880; SEE = 8.37 mmHg). Correlation coefficients were the highest between systolic PAP and the [formula: see text] (r = 0.972; SEE = 4.14), and also between mean PAP and the 10-RV AcT/100 predictor: y = 158x + 6.7 (r = 0.951; SEE = 3.48 mmHg). With +/- 5 mmHg deviations, systolic PAP measurements were accurate in 78% and those of mean PAP in 98% of the patients. The double-blind assessment of the reproducibility of the suggested noninvasive PAP measurement was performed in 18 subsequent patients; the interstudy variability of the measurement was 0.88 +/- 0.94 mmHg and 1.22 +/- 1.23 mmHg (p > 0.05), whereas interobserver variability was 1.90 +/- 1.70 mmHg and 1.67 +/- 1.63 mmHg, respectively (p > 0.05). Thus, a combined use of the most informative intervals of RV cycle--IRT and AcT--contributes to the accuracy of noninvasive PAP measurement.

Isovolumic relaxation time varies predictably with its time constant and aortic and left atrial pressures: implications for the noninvasive evaluation of ventricular relaxation

The isovolumic relaxation time (IVRT) is an important noninvasive index of left ventricular diastolic function. Despite its widespread use, however, the IVRT has not been related analytically to invasive parameters of ventricular function. Establishing such a relationship would make the IVRT more useful by itself and perhaps allow it to be combined more precisely with other noninvasive parameters of ventricular filling. The purpose of this study was to validate such a quantitative relationship. Assuming isovolumic relaxation to be a monoexponential decay of ventricular pressure (pv) to a zero-pressure asymptote, it was postulated that the time interval from aortic valve closure (when pv = p(o)) until mitral valve opening (when pv = left atrial pressure, pA) would be given analytically by IVRT = tau[log(p(o))-log(pA)], where tau is the time constant of isovolumic relaxation and log is to the base e. To test this hypothesis we analyzed data from six canine experiments in which ventricular preload and afterload were controlled nonpharmacologically. In addition, tau was adjusted with the use of beta-adrenergic blockade and calcium infusion, as well as with hypothermia. In each experiment data were collected before and after the surgical formation of mitral stenosis, performed to permit the study of a wide range of left atrial pressures. High-fidelity left atrial, left ventricular, and aortic root pressures were digitized, the IVRT was measured from the aortic dicrotic notch until the left atrioventricular pressure crossover point, and tau was calculated by nonlinear least-squares regression.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of left ventricular isovolumic relaxation time with growth in children

We investigated the changes of left ventricular isovolumic relaxation time (LVIRT) with growth and the factors influencing them during childhood, in a 10-year follow-up study. We measured the body height (BH), body weight (BW), lean body weight (LBW), heart rate (HR), blood pressure (BP), left ventricular muscle volume index (LVMVI), and LVIRT corrected by the preceding R-R interval (IRT/R-R), of 187 healthy children at 3-year intervals (6, 9, 12, 15 years old). IRT/R-R were prolonged with growth in boys and girls. At the ages of 12 and 15, the IRT/R-R of girls were longer than those of boys. Significant correlation coefficients for IRT/R-R on systolic and diastolic, BW, and LVMVI were 0.28, 0.31, 0.20, 0.28, respectively. These data suggest that (1) IRT/R-R is mainly determined by the diastolic BP, (2) left ventricular diastolic function of children develops with growth of body size, especially BW, and (3) left ventricular early diastolic function in adolescents is related to sexual maturation.

Influence of L-thyroxine on cardiac function in athyreotic thyroid cancer patients--an echophonocardiographic study

We have assessed left ventricular performance in twelve athyreotic patients by echophonocardiography during and after their follow-up investigations. Patients were investigated after 4 weeks without and after 2 as well as 4 weeks of therapy with 150-200 micrograms L-thyroxine (L-T4). At the end of 4 weeks withdrawal of L-T4 patients were severely hypothyroid in terms of T4 and thyrotropin (TSH) serum levels as well as total cholesterol plasma levels. In comparison to values obtained in 12 age and sex matched normal controls left ventricular preejection period was prolonged at that time point (110 +/- 20 vs. 90 +/- 20 (SD) ms, p less than 0.05) and the isovolumetric relaxation period (IVRP) was significantly lengthened (78 +/- 16 vs 54 +/- 10 ms, p less than 0.01). Left ventricular ejection phase indices (fractional shortening and mean velocity of circumferential fiber shortening) did not differ significantly from normal. Preejection period dropped to 90 +/- 20 ms (p less than 0.05) after 4 weeks of therapy with L-T4. IVRP decreased to 67 +/- 13 ms (p less than 0.01) but remained significantly prolonged compared to normal. Serum T4, TSH and plasma cholesterol were compatible with borderline hyperthyroidism at that thime point. Thus, systolic as well as diastolic left ventricular performance (especially during isovolumic phases) appear to respond rapidly to thyroid hormone deficiency of short duration and at least partly to resupplementation.

The effects of acute ischemia on the isovolumic index

The isovolumic index is the ratio of the duration of isovolumic contraction (IVC) and relaxation (IVR) divided by ejection time (ET), and has been proposed as a more sensitive descriptor of ventricular performance than the systolic time index, which ignores the period of isovolumic relaxation. To determine the effects of acute ischemia on these indices, IVC, IVR, and ET were measured in seven open-chest dogs instrumented with high-fidelity micromanometers and ultrasonic crystals and subjected to a 10-second period of coronary occlusion. Fractional shortening was significantly impaired (18.4 +/- 6.9% vs 1.9 +/- 7.3%, p less than 0.001) during coronary occlusion. ET was unaffected by the brief ischemia, whereas IVC time showed directional shortening that attained statistical significance (55 +/- 7 msec control vs 50 +/- 6 msec, p less than 0.01) at 8 to 10 seconds. IVR time was prolonged by occlusion, significantly so at 6 to 8 seconds (72 +/- 26 msec control vs 88 +/- 22 msec, p less than 0.01) and at 8 to 10 seconds (81 +/- 19 msec, p less than 0.05). The systolic time index showed no deterioration during ischemia, whereas the isovolumic index did not show directional prolongation. Assessment of IVC, IVR, and ET at the time of the maximal change in the isovolumic index revealed significant changes of IVC and IVR (each p less than 0.05 vs control), though ET and the systolic time index were unchanged. Through incorporation of IVR, the isovolumic index was more sensitive to acute brief ischemia than the systolic time index.

Cardiac hypertrophy in hypertension. Repolarization abnormalities elicited by rapid lowering of pressure

In hypertension, coronary flow is augmented and oxygen balance is adequate despite an increase in coronary resistance. For the maintenance of flow in the presence of and after regression of ventricular hypertrophy, the ratio of pressure and ventricular mass must remain normal. Coronary reserve would be altered if treatment normalized pressure but not ventricular mass or if pressure were lowered too fast. We investigated 42 patients with primary hypertension. In 28 (Group I) left ventricular mass index (by ultrasound) was within the mean value +2 SD (96 + 38 g/m2) of 145 controls and exceeded these values in the remaining 14 patients (Group 2). The diastolic pressure was lowered rapidly to between 85 and 90 mm Hg with two potent vasodilators, nifedipine (sublingually) and nitroprusside, while a 12-lead electrocardiogram was recorded continuously. During both tests, seven patients in Group 2 (responders) showed inversion of normal T waves, in lead I, aVL, and V3-6. These changes waxed and waned in parallel with the pressure fall and recovery and were not attributable to alterations in adrenergic tone, conduction disturbances, variations, or group differences in the QRS axis, QTc interval, heart rate, left ventricular fractional shortening, wall stress, rate of dimension increase in early diastole, or isovolumic relaxation. A ""steal phenomenon'' or passive collapse in compliant coronary lesions during vasodilatation seems unlikely; in fact, patients were free from coronary symptoms, and the electrocardiographic alterations occurred only in seven patients in Group 2, who had a greater left ventricular mass index and required a larger pressure drop to return the diastolic pressure to normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Early diastolic time intervals during hypertensive pregnancy

Early diastolic time intervals have been assessed by means of the echopolycardiographic method in 17 pregnant women who developed hypertension during pregnancy (HP) and in 14 normal pregnant women (N). Systolic time intervals (STI), stroke volume (SV), ejection fraction (EF), and mean velocity of myocardial fiber shortening (VCF) were also evaluated. Recordings were performed in the left lateral decubitus (LLD) and then in the supine decubitus (SD). In LLD, isovolumic relaxation period (IRP) was prolonged in the hypertensive pregnant women compared with normal pregnant women (HP 51 +/- 12.5 ms, N 32.4 +/- 15 ms p less than 0.05), whereas time of the mitral valve maximum opening (DE) was not different in the groups. There was no difference in SV, EF, and mean VCF, whereas STI showed only a significant (p less than 0.05) lengthening of pre-ejection period (PEP) in HP. When the subjects shifted from the left lateral to the supine decubitus position, left ventricular ejection time index (LVETi) and SV decreased significantly (p less than 0.05) in both normotensive hypertensive pregnant women. IRP and PEP lengthened significantly (p less than 0.05) only in normals, whereas they were unchanged in HP. DE time did not vary in either group. In conclusion, hypertension superimposed on pregnancy induces lengthening of IRP, as well as of PEP, and minimizes the effects of the postural changes in preload on the above-mentioned time intervals.

Clinical significance of early diastolic time intervals for the differentiation of idiopathic dilative cardiomyopathy from ischemic cardiomyopathy

In order to differentiate idiopathic dilative cardiomyopathy from ischemic cardiomyopathy noninvasively, systolic time intervals (STIs) and early diastolic time intervals were investigated in patients with idiopathic dilative cardiomyopathy (n = 11), patients with ischemic cardiomyopathy (n = 8), and normal controls (n = 17). Minimal left ventricular pressure and pulmonary capillary wedge pressure (PCWP) were also measured to clarify the relationship between early diastolic time intervals and early diastolic hemodynamics. Cardiac function estimated by STIs was markedly depressed both in idiopathic dilative cardiomyopathy and ischemic cardiomyopathy, and there was no difference between the two diseases. In early diastolic time intervals, IIA-O time (the interval from the aortic component of the second heart sound to the O point of apexcardiogram) was significantly prolonged both in idiopathic dilative cardiomyopathy (144 +/- 31 (SD); p less than 0.01) and ischemic cardiomyopathy (153 +/- 15; p less than 0.01) compared to normal controls (126 +/- 11). IIA-MVO time (the interval from IIA to the mitral valve opening) in idiopathic dilative cardiomyopathy (49 +/- 23) was significantly shorter than that in normal controls (70 +/- 8; p less than 0.05). On the contrary, IIA-MVO time in ischemic cardiomyopathy (126 +/- 11) was markedly prolonged compared with normal controls (p less than 0.01) and idiopathic dilative cardiomyopathy (p less than 0.01). MVO-O time was significantly prolonged in idiopathic dilative cardiomyopathy (94 +/- 18; p less than 0.01). However, it was conversely shortened in ischemic cardiomyopathy (25 +/- 15) compared with normal controls (54 +/- 7; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Regional variation in the timing and extent of left ventricular wall motion in normal subjects

Right anterior oblique cineangiograms from 19 subjects without evidence of heart disease were analysed to assess regional non-uniformity in the time of onset of systolic inward motion, amplitude of systolic motion, time of peak inward motion, and wall motion during the isovolumic relaxation period. The left ventricular silhouette was digitised frame by frame for a full cardiac cycle. These four wall motion variables were quantitatively measured along 40 chords drawn from equally spaced points on the end diastolic silhouette to the nearest point on the end systolic silhouette. Onset of systolic inward motion was significantly non-uniform, being delayed by up to 120 ms in the anterior apical chords compared with the areas of earliest inward motion near the base of the heart. More uniformity was noted in time of peak inward motion; the differences between regions were not statistically significant. Amplitude of systolic motion was significantly less at the apical and mid-anterior segments than elsewhere in the heart. Wall motion during the isovolumic relaxation period is outward and greatest in the mid-anterior segments, but inward in the proximal inferior segments and mitral valve region. These data suggest that contraction of muscle fibres in the anterior apical segments is initially isometric due to the considerable afterload at the onset of contraction, this afterload being the result of earlier contraction elsewhere in the ventricle. This may partly explain the propensity for aneurysms to be located in the anterior apical region. When the timing and extent of wall motion in disease states are analysed, account must be taken of the non-uniformity in the normal heart.

Noninvasive evaluation of systolic and diastolic function in severe congestive heart failure secondary to coronary artery disease or idiopathic dilated cardiomyopathy

The usefulness of systolic time intervals, diastolic time intervals and echocardiography in evaluating left ventricular (LV) function was determined in 69 patients with severe congestive heart failure. All systolic time intervals were markedly abnormal (preejection period/LV ejection time 0.59 +/- 0.18 vs 0.30 +/- 0.04, preejection period index 170 +/- 37 vs 117 +/- 11, LV ejection time index 372 +/- 26 vs 410 +/- 17; patients vs control subjects, p less than 0.05). Diastolic time intervals in patients were not different from those in control subjects. Echocardiographic measurements were all markedly abnormal (LV end-diastolic dimension 6.9 +/- 1.0 vs 4.8 +/- 0.4 cm, patients vs control subjects, p less than 0.05). No pattern of abnormalities distinguished ischemic cardiomyopathies from idiopathic dilated cardiomyopathies. The presence of LV conduction delay did not substantially alter results, except that exclusion of patients with LV conduction delay normalized the total time of systole (QA2) index (from 542 +/- 40 to 531 +/- 31 ms) and reduced but did not normalize prolongation in the preejection period index (from 170 +/- 37 to 162 +/- 29 ms). No systolic or diastolic interval strongly correlated with any hemodynamic or other independent measure of LV performance. Twenty-four patients were given inotropic or unloading agents, which significantly improved hemodynamic values. Systolic and diastolic intervals were measured at baseline and at maximal hemodynamic effect. The correlation of changes in hemodynamics with changes in systolic and diastolic intervals was only modest. Thus, although systolic time intervals and associated echocardiographic measurements can detect abnormal LV function, they cannot reliably detect a change in LV function or distinguish gradations of abnormality.(ABSTRACT TRUNCATED AT 250 WORDS)

The relation of heart rate and shortening fraction to echocardiographic indexes of left ventricular relaxation in normal subjects

To determine the relation of heart rate and systolic function to echocardiographically derived indexes of left ventricular relaxation, M-mode echocardiograms of the left ventricle and mitral valve with a simultaneous phonocardiogram were recorded at rest from 28 normal men. The effects of altering the inotropic state and ventricular loading conditions were examined during isometric handgrip exercise and the Valsalva maneuver in a subset of 15 men. The left ventricular endocardial echocardiograms were digitized to provide a display of left ventricular internal dimension and its first derivative (dD/dt). The time course of relaxation, defined as the interval from left ventricular minimal systolic dimension to the point when the rate of change of dimension (dD/dt) decreased to 50% of peak, was directly related to the RR interval (r = 0.64, p less than 0.0001) in the entire group, and this relation remained throughout the interventions. The slopes of the regression lines of relaxation time (RT) and electromechanical systole (QS2) on the RR interval were similar. Diastolic time decreased proportionately more than relaxation time as the RR interval decreased, so that the proportion of diastole occupied by the relaxation time varied with cycle length. Peak diastolic dD/dt, normalized for variations in end-diastolic dimensions [( dD/dt]/D), was directly related to left ventricular shortening fraction (r = 0.71 p less than 0.0001) and this relation remained during isometric grip. There was no correlation between the heart rate at rest and (dD/dt)/D over the range of 44 to 99 beats/min.(ABSTRACT TRUNCATED AT 250 WORDS)