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PubMed1998

[A failed improvement in pulmonary function and exercise capacity with carvedilol in congestive heart failure despite an excellent effect on left ventricular function].

This study was aimed at investigating in chronic heart failure (CHF) the effects that beta-blockade with carvedilol may have on lung function, and their relationship with left ventricular (LV) performance and peak exercise oxygen uptake (VO2p). CHF causes disturbances in ventilation and pulmonary gas transfer (stress failure of alveolar-capillary membrane) that participate in limiting VO2p. Carvedilol improves LV function and not VO2p. Twenty-one NYHA functional class II-III patients were randomized (2 to 1) to carvedilol (25 mg bid., 14 patients) or placebo (7 patients) for 6 months. Rest forced expiratory volume (FEV1), vital capacity (VC), total lung capacity (TLC), carbon monoxide diffusing capacity (DLCO), its alveolar-capillary membrane component (DM), pulmonary venous and transmitral flows (for monitoring changes in LV end-diastolic pressure, EDP), LV diastolic (EDD) and systolic (ESD) dimensions, stroke volume (SV), ejection fraction (EF), fiber shortening velocity (VCF) were measured at baseline and at 3 and 6 months. VO2p, peak ratio of dead space to tidal volume (VD/VTp), ventilatory equivalent for CO2 production (VE/VCO2), VO2 at anaerobic threshold (VO2at) were also determined. FEV1, VC, TLC, DLCO, DM were impaired in CHF compared to 14 volunteers, and did not vary with treatment. Carvedilol reduced EDP, EDD, ESD, and increased EF, SV, VCF, without affecting VO2p, VO2at, VD/VTp, VE/VCO2, at 3 and 6 months. Placebo was ineffective. In CHF, carvedilol exerts neutral effects on ventilation and pulmonary gas transfer and ameliorates LV function at rest. This proves that antifailure treatment may not be similarly effective on cardiac and pulmonary function; and does not contradict the possibility that persistence of lung impairment may contribute to lack of improvement in exercise performance with carvedilol.

Adrenergic beta-Antagonists↗

PubMed1995

[Prediction of left ventricular functional recovery in patients with acute myocardial infarction using single photon emission computed tomography with thallium-201 and iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid].

The relationships between myocardial perfusion, fatty acid metabolism, and cardiac function were investigated using dual single photon emission computed tomography (SPECT) with thallium and iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid (123I-BMIPP) during the acute (10 +/- 1 days) and recovery (60 +/- 14 days) phases in 29 patients with acute myocardial infarction. There were 18 patients who underwent successful primary coronary angioplasty (PTCA group) and 11 patients who received conservative therapy (non PTCA group). Thallium and BMIPP uptakes were scored visually by a 4-point system and left ventricular ejection fraction (LVEF) was calculated by radionuclide ventriculography. Although significant positive correlations between thallium and 123I-BMIPP scores were observed during both phases, BMIPP scores were significantly lower than thallium scores in both acute and recovery phases in the PTCA group. No significant difference in thallium and 123I-BMIPP scores was observed at the recovery phase in the non PTCA group. LVEF significantly correlated with thallium and 123I-BMIPP scores in both phases in the PTCA group. Furthermore, the difference between thallium and 123I-BMIPP scores during the acute phase significantly correlated with the improvement of LVEF during the follow-up period in the PTCA group (y = 0.92x-0.77, r = 0.65, p < 0.005). These findings suggest that mismatch of perfusion and metabolism in infarcted myocardium assessed by thallium and 123I-BMIPP SPECT is increased by reperfusion therapy and persists at least until the recovery phase of myocardial infarction. The recovery of left ventricular function depends on the extent of the mismatched uptake, indicating a predictor for functional recovery following acute myocardial infarction.

Adult↗

PubMed1979

Echocardiographic evaluation of left ventricular function in children with congestive cardiomyopathy.

Echocardiography was used to study left ventricular function in 37 children with congestive cardiomyopathy. Left atrial and left ventricular diameters were approximately 1.5 times that predicted by body weight, whereas systolic decrease in left ventricular diameter (shortening fraction) and increase in posterior wall thickness were half that of normal children. The ratio of left ventricular preejection period to ejection time was increased in 25 patients and normal in 10. The mean velocity of circumferential fiber shortening was decreased in 30 of 34 patients and averaged 52 percent of that predicted by heart rate. The shortening fraction was higher in the 12 patients who were asympatomatic at the time of study than in the 25 who had symptoms of congestive heart failure (19.6 +/- 2.4 standard error of the mean versus 14.6 +/- 1.2) (P less than 0.05). In 11 patients whose condition improved after therapy with digoxin and diuretic drugs, serial echocardiograms showed significant increases in shortening fraction and posterior wall thickening and decreases in left atrial diameter and the ratio of preejection period to ejection time. However, one or more indexes of left ventricular function remained abnormal, despite the resolution of symptoms and a return of heart size to normal as judged from the chest roentgenogram.

Adolescent↗

PubMed1995

Predictors of mortality in patients with sustained ventricular tachycardias or ventricular fibrillation and depressed left ventricular function: importance of beta-blockade.

To study prognostic factors in patients with sustained ventricular tachycardias (VT) or ventricular fibrillation (VF) complicated by left ventricular dysfunction, we evaluated the predictive value of demographic, clinical, and hemodynamic parameters for cardiac mortality and sudden cardiac death in 85 patients with VT or VF and left ventricular ejection fraction < 0.45 (mean 0.27 +/- 0.10). Patients underwent serial drug testing and received appropriate antiarrhythmic treatment, with amiodarone given as last-resort therapy. During a follow-up of 24 +/- 13 months, 23 patients died of cardiac causes, and 18 of them died suddenly. Left ventricular ejection fraction < or = 0.27 and amiodarone treatment were related to greater cardiac mortality and increased risk of sudden cardiac death, whereas beta-blockade was associated with improved survival. In the multivariate model cardiac mortality was best predicted by a left ventricular ejection fraction < or = 0.27, and absence of beta-blockade and severe left ventricular dysfunction were the strongest predictors of sudden cardiac death. We conclude that severe left ventricular dysfunction predicts increased cardiac mortality and high risk of sudden cardiac death. Moreover, beta-blocking treatment is associated with lower cardiac mortality and a reduced risk of sudden cardiac death in patients with sustained VT or VF and depressed left ventricular function. beta-Blocking agents may therefore be an important addition to conventional antiarrhythmic treatment in patients with VT or VF and left ventricular dysfunction.

Adrenergic beta-Antagonists↗

PubMed2000

Evaluation of global and regional left ventricular function obtained by quantitative gated SPECT using 99mTc-tetrofosmin for left ventricular dysfunction.

OBJECTIVE: The quantitative gated SPECT (QGS) software is able to calculate LV volumes and visualize LV wall motion and perfusion throughout the cardiac cycle using an automatic edge detection algorithm of the left ventricle. We evaluated the reliability of global and regional LV function assessment derived from QGS by comparing it with the results from left ventriculo-cineangiography (LVG). PATIENTS: In 20 patients with left ventricular dysfunction who underwent ECG gated 99mTc-tetrofosmin SPECT, the end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (LVEF) were calculated. The QGS-assessed regional wall motion was determined using the cinematic display. RESULTS: QGS-derived EDV, ESV and LVEF correlated well with those by LVG (p<0.001 for each). There was a good correlation between wall motion score (WMS) derived from the QGS and the LVG (r=0.40, p<0.05). In some patients with extensive myocardial infarction, there was a discrepancy in the regional wall motion results between QGS and LVG. CONCLUSIONS: The ECG-gated SPECT using QGS is useful to evaluate global and regional LV functions in left ventricular dysfunction.

Adult↗

PubMed1996

Limiting lipid peroxidation in the nonischemic zone of infarcted rat hearts by indomethacin improves left ventricular function without affecting myocardial healing and remodeling.

We recently showed that indomethacin reduces lipoperoxidation occurring in the nonischemic zone (right ventricle + septum; RVS) of rat hearts with permanent coronary occlusion. The purpose of this study was to determine whether this biochemical effect is associated with an improvement of residual cardiac function or with modifications of delayed ventricular remodeling, or both. Rats received either indomethacin (1 mg/kg i.p.) or a placebo 5 min before coronary occlusion, and then twice a day for 48 hours. Six hours after ligation, myeloperoxidase (MPO) activity (leukocyte infiltration index) was measured in the ischemic zone (left ventricle; LV) and in RVS. Forty-eight hours after ligation, left ventricular function was assessed in vivo. Alterations in myocardial geometry were estimated 21 days after ligation on histologic cross-sections. In the indomethacin group, cardiac function was improved compared with that with placebo, and the indexes of ventricular remodeling were not affected by the treatment. Finally, indomethacin at the dose used did not affect MPO activity in the LV. It is concluded that indomethacin treatment leads to a better maintenance of residual nonischemic tissue contractility without worsening late ventricular shape changes. These results could in part be explained by the ability of the treatment to decrease inflammatory mediator-induced oxidative stress in RVS without affecting infarct healing caused by leukocyte infiltration in LV.

Animals↗

PubMed1998

Recovery from end-stage ischemic cardiomyopathy during long-term LVAD support.

A patient with ischemic cardiomyopathy and extremely reduced left ventricular function (left ventricular ejection fraction=0.10) presented to our institution for cardiac transplantation. Because of his worsening condition he was placed on the Novacor left ventricular assist device. During 3 months of support his left ventricular function recovered and he successfully underwent percutaneous transluminal coronary angioplasty and minimally invasive direct coronary artery bypass grafting procedures; subsequently he could be weaned from the left ventricular assist device and discharged. The patient is no longer considered for cardiac transplantation.

Angioplasty, Balloon, Coronary↗

PubMed1991

[Pathologic movements of the ventricular septum in complete block of the left branch of the bundle of His and their effect on left ventricular function].

Echocardiographic tools (M-mode and 2D-scanning) were applied to examine 83 patients with complete bundle-branch block and/or its anteroapical bifurcation block. Six types of abnormal ventricular septal motions associated with the intraventricular asynchronism typical of complete bundle-branch block and with the specific features of electric pulse propagation in the His-Purkinje system were identified. There was a reduction in left ventricular ejection fraction that is peculiar to Types I and VI abnormal ventricular septal motions, whereas in patients with complete bundle-branch block, it is associated with anteroapical bifurcation block. A moderate decrease in ejection fraction is more common for Types III and IV abnormal ventricular septal motions (despite the severity of cardiac disease). Complete bundle-branch block alone and in combination with anteroapical bifurcation block contributes to a decrease in left ventricular function and diminished myocardial contractility. Whether the severity of complete bundle-branch block affects cardiodynamics is discussed in the present paper.

Adult↗

PubMed1994

Effects of canine donor heart preservation temperature on posttransplant left ventricular function and myocardial metabolism.

The generally accepted method of preserving donor heart integrity during transfer is to arrest it with cold cardioplegic solution, then store it in a plastic bag immersed in an iced electrolyte solution. Temperatures between 0 degree C and 4 degrees C are maintained by this method until the heart is transplanted. Although profound hyperthermia best inhibits metabolic processes, it may damage the myocardium. Higher myocardial temperatures may be more advantageous and may result in better preservation. The efficacy of this hypothesis has been investigated in a canine model. The hearts of 40 dogs were isolated, arrested with cold cardioplegia, removed from the animal, and stored at different temperature ranges from 0-3 degree C to 12-15 degrees C for 4 hr. After this time period, the hearts were transplanted into a recipient animal in the cervical heterotopic position. The degree and speed of myocardial functional recovery were monitored by measuring end-systolic elastance generated from pressure-diameter loops using sonomicrometry techniques. Myocardial metabolism was studied simultaneously by monitoring coronary flow, O2, glucose, lactate, pyruvate, and free fatty acid uptakes. The results were compared with those from a control group of hearts transplanted immediately after their removal. Our results indicate that donor heart function was significantly depressed 30 min after heterotopic transplantation, but returned to "control" levels after 2 hr when stored between 0 degrees C and 6 degrees C. Myocardial function remained significantly depressed throughout the 2-hr recovery period in hearts stored at higher (6-15 degrees C) temperatures. Hearts stored at all temperatures continued to extract glucose, lactate, and free fatty acids, but produced significantly higher levels of pyruvate at higher storage temperatures, which may be related to the favored use of free fatty acids. In conclusion, donor hearts stored at colder temperatures for 4 hr regain complete left ventricular function faster than hearts stored at higher temperatures. Our experiments support the presently applied methods of donor heart preservation for 4 hr.

Animals↗

PubMed2006

[Influence of preload reduction on Tei index and other Doppler echocardiographic parameters of left ventricular function].

OBJECTIVE: To assess the influence of preload reduction by hemodialysis on Doppler Tei Index of myocardial performance and other parameters of cardiac function. METHODS: The Tei index and left ventricular (LV) systolic and diastolic function parameters were estimated, before and after a single hemodialysis session. Only subjects who were in sinus rhythm, without history of coronary artery disease, and no evidence of cardiac valve disease and pericardial effusion were included in the study. RESULTS: Fifteen patients (8 men, mean age 53 +/- 14 years) completed the study. After an ultrafiltration of 2.2 +/- 1.1 liters, peak mitral E velocity decreased (p < 0.05) and A velocity remained unchanged (p = ns), resulting in reduction of E/A ratio (p < 0.01). The Tei index increased (from 0.57 +/- 0.07 to 0.65 +/- 0.09, p < 0.01) because of significant prolongations in isovolumetric relaxation time (from 101 +/- 14 to 113 +/- 17 ms, p < 0.01) and ejection time (from 271 +/- 22 to 252 +/- 22, p < 0.05). The isovolumetric contraction time did not vary (p = ns). There was no change in diastolic tissue Doppler parameters, while systolic velocities increased (p < 0.05). CONCLUSION: The Tei index was affected by hemodialysis-induced preload alterations, as well as other mitral inflow Doppler-derived parameters. The diastolic parameters of mitral annulus Doppler tissue were independent of preload, while systolic velocities suggested improved systolic function.

Blood Flow Velocity↗

PubMed1988

[Study of the correlation between severity of hypertension and the left ventricular mass and left ventricular functions].

The correlation between the severity of hypertension and the left ventricular mass and left ventricular functions were studied in normal controls (n = 6) and essential hypertensives (n = 37). And we studied the factors that influence on the severity of hypertension by discriminant analysis. Thirty-seven hypertensives were divided into three groups (WHO I 16, WHO II 16, WHO III 5). The left ventricular mass (LVM) was calculated by X-ray computed tomography. The %fractional shortening (%FS), mean Vcf (mVcf) and ejection fraction (EF) were obtained as left ventricular systolic function by echocardiogram. The left ventricular diastolic posterior wall velocity (PWVd) and left ventricular rapid filling volume/stroke volume (RFV/SV) were obtained as left ventricular diastolic function by echocardiogram. The LVMs (g/m2) of controls, WHO I, WHO II and WHO III were 92 +/- 14, 113 +/- 23, 155 +/- 56 and 237 +/- 38. The LVM were great as the stage of hypertension was deteriorated. The left ventricular diastolic function was impaired as hypertension exacerbated. The left ventricular systolic function was not changed in four groups including controls. The LVM was significantly well correlated with systolic blood pressure (r = 0.48, p less than 0.01), diastolic blood pressure (r = 0.30, p less than 0.05), cardiothoracic ratio (r = 0.36, p less than 0.05), SV1 + RV5 on ECG (r = 0.66, p less than 0.001) and left ventricular diastolic function (PWVd; r = 0.49, p less than 0.01, RFV/SV; r = 0.52, p less than 0.001). But, the LVM was poor correlated with left ventricular systolic function. Depending on the discriminant analysis, the LVM and left ventricular diastolic function had significantly well influence on the severity of hypertension and ECG abnormality. As using the LVM calculated by computed tomography, we have exactly and useful informations of essential hypertension.

Adult↗

PubMed1996

Low-dose dobutamine echocardiography and rest-redistribution thallium-201 tomography in the assessment of spontaneous recovery of left ventricular function after recent myocardial infarction.

Spontaneous improvement of contraction and perfusion occurs after acute myocardial infarction. The relative merit of low-dose dobutamine stress echocardiography (LDDE) and rest-redistribution thallium scintigraphy (RR TI) in this setting has not been evaluated. We studied 30 patients at 7 +/- 3 days after acute myocardial infarction with LDDE (5 to 10 micrograms/kg/min) and RR TI single photon emission computed tomography. Viability was defined as improvement of wall thickening at LDDE in the presence of redistribution or a defect with uptake > or = 50% of peak activity at RR TI. Baseline echocardiography and RR TI were repeated after 3 months. In 112 dyssynergic segments, viability was detected in 60 (54%) by RR TI and in 39 (35%) by LDDE (p < 0.005). Spontaneous improvement of function was detected in 35 (31 %) segments. In the same regions, thallium uptake increased significantly. The sensitivity, specificity, and accuracy of LDDE for predicting late improvement of wall motion were 77%, 84%, and 82%, respectively. Those of RR TI were 77%, 57%, and 63%, respectively. Specificity and accuracy of LDDE were higher than RR TI (p < 0.005). We conclude that a myocardial viability pattern after acute myocardial infarction is more frequently detected by RR TI than by LDDE. Both techniques are equally sensitive, but LDDE is a more specific predictor of spontaneous recovery of regional left ventricular function.

Adrenergic beta-Agonists↗

PubMed1995

Quinidine pharmacodynamics in patients with arrhythmia: effects of left ventricular function.

OBJECTIVES: This study was undertaken to determine whether quinidine pharmacodynamics are altered in the presence of left ventricular dysfunction. BACKGROUND: Left ventricular function is an independent predictor of antiarrhythmic drug efficacy. However, the effects of left ventricular dysfunction on the pharmacodynamics of antiarrhythmic drugs have not been studied extensively. METHODS: Signal-averaged electrocardiograms were obtained and quinidine plasma concentrations measured during 24-h quinidine washout in 22 patients. RESULTS: Linear quinidine concentration-effect relations were observed for QRS and QT intervals corrected for heart rate. The slopes of the concentration-effect relation describing changes in the corrected QT (QTc) interval were significantly higher in the group with left ventricular ejection fraction > or = 0.35 ([mean +/- SD] 29.5 +/- 11.2 ms/micrograms per ml) than in the group with a low left ventricular ejection fraction (15.7 +/- 9.7 ms/micrograms per ml, p = 0.001). The QRS concentration-effect relations were not different in the two groups. A significant linear correlation was observed between the slopes of the concentration-effect relations describing changes in QTc intervals and left ventricular ejection fraction (r = 0.7, p < 0.001). Nineteen patients with inducible ventricular tachycardia underwent serial electrophysiologic studies for evaluation of quinidine efficacy. Ventricular tachycardia could not be induced during quinidine therapy in eight patients. The slopes of the quinidine concentration-effect relations for QTc intervals were significantly higher in quinidine responders than in nonresponders (p < 0.05). CONCLUSIONS: The effects of quinidine on ventricular repolarization are linearly related to left ventricular ejection fraction. Quinidine concentration-effect relations describing ventricular repolarization are associated with antiarrhythmic efficacy in patients with ventricular tachycardia.

Cardiac Pacing, Artificial↗

PubMed2002

Benefits of late reperfusion in the treatment of acute myocardial infarction.

Early reperfusion of the infarct-related coronary artery is very much effective to treat the patients with acute myocardial infraction. However, there are many clinical as well as experimental evidences supporting the efficacy of late reperfusion therapy. In this article, effects of late reperfusion on mortality, left ventricular function, left ventricular dilatation and remodeling, or electrical stability were summarized. Also, the possible mechanisms for benefits of late reperfusion were discussed and the special role of epicardial rim bring about those benefits was emphasized.

Animals↗

PubMed2004

Predictors of improvement in left ventricular function after initially successful angioplasty of unprotected left main coronary artery stenoses.

BACKGROUND: Percutaneous coronary intervention (PCI) has been increasingly applied to unprotected left main coronary artery (LMCA) lesions, with varied procedural success and clinical outcomes. However, the effect of PCI on left ventricular performance is still unclear, and there are no clinical studies assessing factors that influence left ventricular ejection fraction (LVEF) in these cases. METHODS: Between April 1986 and August 2002, de novo PCI was performed for unprotected LMCA stenoses in 199 patients. Close clinical and angiographic follow-up were conducted after the procedure. RESULTS: One hundred eighty patients survived over six months and analysis of paired left ventriculography was possible in 175 patients. Improvement in LVEF was observed in the entire population (52.9 +/- 15.7% to 56.1 +/- 14.3%, p = 0.048). The LVEF change was 6.7 +/- 9.5% (p < 0.01) in group with baseline LVEF < or = 50% and 0.7 +/- 6.7 % (p = NS) in group with LVEF > 50%. There was significant intergroup difference (p < 0.001). Patients with baseline diameter stenosis > or = 60% had an improvement of 5.3 +/- 8.3% (p < 0.05) whereas those with stenosis < 60% had no improvement (2.0 +/- 8.4%, p = NS). CK-MB elevation > or = 3 times normal after PCI had a significant inverse association with improvement in LVEF (p < 0.05). Multivariate analysis revealed baseline LVEF < or = 50% was the only independent predictor of improvement in LVEF (standard estimate = 3.509, 95% CI: 2.164-4.854, p < 0.001). CONCLUSIONS: Successful PCI procedure is associated with significant improvement in LVEF, especially in patients with depressed left ventricular function.

Aged↗

PubMedDate not supplied

Role of plasma catecholamines, autonomic, and left ventricular function in normotensive and hypotension prone dialysis patients.

The current study looked at plasma catecholamines, clinical autonomic function tests, and hemodynamic parameters in 10 ESRD patients (five men and five woman, aged 56.4 +/- 3.6) with dialysis hypotension and 10 patients (five men and five women, aged 58.6 +/- 4.2) without dialysis hypotension. Catecholamines were measured using high performance liquid chromatography--electrochemical detection (HPLC-ECD). Dialysis led to a significant decrease in mean arterial pressure (MAP) in the hypotensive group as compared with the normotensive group. Significantly higher basal (predialysis) plasma norepinephrine (NE) and dopamine levels (DA) were found in the hypotensive uremic group as compared with the normotensive group. Levels of plasma epinephrine (EP) were not significantly different between the normotensive and hypotensive groups. In response to postural stimulation, blood pressure fell in both groups, but the fall in the hypotensive group was significantly greater. Percentage increments of plasma catecholamines in response to postural stimulation in both groups were similar, however. Among the measured hemodynamic parameters, including total peripheral vascular resistance and left ventricular function (cardiac index and fractional shortening), only the cardiac index showed significantly lower values in the hypotensive group after dialysis, as compared with the normotensive group. Results of four tests of autonomic function indicated that although both groups responded similarly to hand-grip and cold-pressor tests, impaired responses to orthostasis and Valsalva maneuver after dialysis were observed in the hypotensive group. The MAP changes in dialysis in the hypotension prone group correlated inversely with predialysis plasma NE, but not with EP and DA.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System↗

PubMed1987

Influence of left ventricular function on changes in plasma volume during acetate and bicarbonate dialysis.

The effect of left ventricular function on changes in plasma volume during acetate and bicarbonate dialysis was studied in stable, chronic dialysis patients. Preservation of plasma volume in patients with a normal left ventricular function (mean circumferential fibre shortening velocity (VcF) greater than or equal to 1 circ/s) was significantly less during the first hour of acetate dialysis than during bicarbonate dialysis. However, in patients with impaired left ventricular function (VcF less than 1 circ/s) the decrease in plasma volume was more pronounced during acetate when compared to bicarbonate dialysis. This resulted in a decreased ultrafiltration volume and haemodynamic instability in these patients during acetate dialysis. The fibre shortening velocity increased during acetate and bicarbonate dialysis in patients with a normal left ventricular function, whereas in patients with impaired left ventricular function fibre shortening velocity increased only during bicarbonate dialysis. In conclusion, in patients with an impaired left ventricular function, bicarbonate is preferable to acetate in chronic dialysis.

Acetates↗

PubMed1992

[The effect of heart rate on the time constant of isovolumic relaxation of the left ventricle].

A time constant (T) of the left ventricular isovolumic relaxation, which expresses the relaxation rate of the left ventricle, may be affected by change of the heart rate. There are few clinical reports concerning the relationship between T and heart rate. We studied the relationship between T and heart rate in 10 patients with normal coronary arteries and left ventricular function. Left ventricular pressure was measured using a catheter-tip manometer during right atrial pacing, which was performed at the rate of 10, 20, 40 beats/min in addition to the baseline rate, and finished at 140 or 150 beats/min. Two measurements were made for T.1) Tw from the slope of In (pressure) against time, and 2) Tb by exponential analysis which also estimated the asymptote. As the heart rate increased, both Tw and Tb gradually shortened (Tw: from 38.5 +/- 4.9 msec at the control heart rate to 28.9 +/- 5.6 msec at 140 or 150 beats/min; Tb: from 54.7 +/- 11.4 msec at the control heart rate to 34.9 +/- 5.7 msec at 140 or 150 beats/min). These findings suggest that left ventricular isovolumic relaxation is strongly affected by change of the heart rate in man.

Adult↗