Changes In Systolic Time Intervals Research Articles

Sumatriptan and 5HT1 Mediated Changes in Systolic Time Intervals

Sumatriptan and 5HT1 Mediated Changes in Systolic Time Intervals

Thoracocardiographic-Derived Left Ventricular Systolic Time Intervals

Thoracocardiography noninvasively estimates left ventricular performance by recording ventricular volume curves with inductive plethysmography. We studied timing of these curves to evaluate their potential to accurately track systolic time intervals in comparison with standard methods. Thoracocardiographic left ventricular volume curves, carotid pressure pulses determined by applanation tonometry, the phonocardiogram and ECG were recorded simultaneously in ten normal subjects at various body positions achieved with a tilt table. An equation was derived to predict preejection period from onset of ejection in thoracocardiographic curves. Ventricular ejection time was calculated as total electromechanical systole obtained by phonocardiography minus preejection period. The equation was validated prospectively in 31 measurements in critically ill patients. In normal subjects, the interval ECG Q wave to ejection onset in thoracocardiographic curves correlated well with preejection period from applanation tonometry and phonocardiography (r = 0.92; standard error of estimate (SEE), 8 ms; p < 0.001). Thoracocardiographic curves showed a delay that varied with body position according to the regression equation: delay = 40 ms + 10 x sine (tilt angle) (where r = 0.62; SEE, 7 ms; p < 0.001). Application of this equation in the prospective study in patients revealed close agreement in systolic time intervals from thoracocardiography and simultaneous applanation tonometry plus phonocardiography, respectively. The mean difference +/- SD between methods in preejection periods was 3 +/- 7 ms and in the ratios of preejection period to left ventricular ejection time, 0.02 +/- 0.05. Trends of changes in systolic time intervals were identical for the two methods. We conclude that thoracocardiography combined with phonocardiography provides accurate systolic time intervals when corrected for a position-dependent delay of its waveforms.

Altered cardiovascular responsiveness to adrenoceptor agonists in endurance-trained men

The influence of physical training on responses to intravenous infusions of phenylephrine (Phe) and isoproterenol (Iso) were investigated in 10 well-trained runners (WT) and 10 age-matched untrained controls (UT). The latter were reinvestigated after a 4-mo training period. The venous plasma Iso and Phe concentrations attained during infusions were lower in WT than in UT. Responses were related to the corresponding plasma concentrations. Phe-induced decreases and Iso-induced increases in heart rate were less pronounced (P less than 0.01) in WT than in UT. At venous plasma concentrations of 100 nM Phe and 0.8 nM Iso, the responses were -9 +/- 1 and 30 +/- 2, and -17 +/- 2 and 44 +/- 4 beats/min, respectively. Increases in blood pressures during Phe infusions were greater in WT than in UT (100 nM Phe: systolic 36 +/- 3 vs. 25 +/- 3 mmHg, P less than 0.05). The Iso-induced decrease in diastolic blood pressure was also more pronounced in WT (0.8 nM Iso: -29 +/- 3 vs. -15 +/- 2 mmHg, P less than 0.01). Iso-induced changes in systolic time intervals showed no consistent differences between training states. Increases in plasma adenosine 3',5'-cyclic monophosphate during Iso infusions were smaller (P less than 0.05) in WT than in UT, whereas increases in plasma glycerol were larger (P less than 0.05). Lymphocyte beta 2-adrenoceptor function and binding characteristics did not differ between training states. In summary, the present results indicate that beta-adrenergic vasodilator and alpha-adrenergic vasopressor responses are enhanced in endurance-trained subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical, haemodynamic, and pharmacological effects of withdrawal and reintroduction of digoxin in patients with heart failure in sinus rhythm after long term treatment.

A randomised, double blind, placebo controlled, crossover study of digoxin withdrawal and reintroduction was carried out over two periods of eight weeks each after long term treatment. Forty four patients with stable heart failure in sinus rhythm and plasma digoxin concentrations over 0.8 ng/ml were studied. Their progress was assessed by clinical criteria, by haemodynamic measurements (systolic time intervals and echocardiography), and by pharmacological measurements of erythrocytic sodium pump numbers and activity. After withdrawal of digoxin clinical deterioration occurred in only 25% of the patients. Furthermore, in only 9% of cases was digoxin reintroduction thought to be necessary. There was deterioration in only 11% of the patients during digoxin treatment. Deterioration during digoxin withdrawal was accompanied by changes in systolic time intervals, but similar, albeit smaller changes in systolic time intervals also occurred in patients with no deterioration. Deterioration was accompanied by changes in the pharmacological effects of digoxin on the erythrocytes, consistent with a loss of effect, and these changes did not occur in those who did not deteriorate. The occurrence of deterioration could not be predicted by any clinical, haemodynamic, or pharmacological measurements made before withdrawal.

Left ventricular performance determined by ambulatory monitoring of systolic time intervals during daily activities in the late hospital phase of acute myocardial infarction

The ambulatory electrocardiogram is a useful method for detecting complex arrhythmias in the late hospital phase of acute myocardial infarction (AMI) and exercise testing is usually used to detect cardiac reserve or ischemia or both.1,2 However, the changes in left ventricular (LV) performance during various daily activities cannot always be reproduced by the standard exercise test. Systolic time interval calculation is a useful noninvasive measure of cardiac function; ear densitography makes possible precise observation of changes in systolic time intervals under various conditions including upright exercise.3–5 We investigated the long-term ambulatory response of systolic time intervals during daily activities in patients recovering from AMI to evaluate the changes in LV performance to daily stresses.

Isolated pulmonary valve prolapse: A sign of pulmonary hypertension

Isolated pulmonary valve prolapse may be a sign of pulmonary hypertension. Three patients with pulmonary hypertension as a result of left ventricular failure, chronic obstructive pulmonary disease, and primary pulmonary hypertension, respectively, are described in the case reports. It is likely that the morphological change of the pulmonary valve is due to exaggeration of the normal convexity of the elastic pulmonary leaflets as a result of a high pulmonary artery diastolic pressure. This two-dimensional echocardiographic sign may prove to be a useful qualitative hallmark for pulmonary hypertension. Present methods to detect pulmonary hypertension by two-dimensional echocardiography rely on remote findings of right heart abnormalities or changes in systolic time intervals. Pulmonic valve prolapse is the first direct sign of pulmonary hypertension found on two-dimensional echocardiography.

Noninvasive Estimates of Cardiac Performance during and Early after Single and Repeated Passive Upright Tilt in Normal Men: Volume Dependency of Systolic Time Intervals and Maximum Velocity of Transthoracic Impedance Changes

The combination of electrocardiography, impedance cardiography and phonocardiography allows to measure systolic time intervals and maximum velocity of transthoracic impedance changes (dZ/dt(max)) as estimates of (changes in) cardiac performance. Such assessment was performed in 35 normal male subjects undergoing single gradual passive upright tilting and 11 subjects undergoing repeated upright tilting. During tilting a cardio-acceleratory and vasopressor response is evident in compensation for the largely reduced stroke volume as a consequence of the reduced preload. During upright tilting, heart rate-corrected preejection pressure (PEP) was prolonged, heart rate-corrected left ventricular ejection time (LVET) was shortened and PEP/LVET was increased, and dZ/dt(max) and related parameters were reduced during upright tilting. These changes most likely reflect the preload dependency of these parameters even to such an extent that they could not reflect net inotropic changes related to the increased adrenergic activity during tilting. During the first 10 min after upright tilt, dZ/dt(max) and estimated stroke volume were increased versus supine baseline prior to tilt, whereas the return of the estimated thoracic blood volume back to baseline was delayed. This was associated with a relative bradycardia and slight reduction in diastolic blood pressure. These changes reached their maximum on average 3–4 min after the supine position was resumed. This enhanced cardiac pump performance early after tilt, suggested by dZ/dt(max) and related parameters, was not associated with corresponding changes in systolic time intervals. Although both systolic time intervals and dZ/dt(max) may be volumedependent, dZ/dt(max) and related parameters may offer additional information on cardiac performance not derivable from systolic time intervals.

Haemodynamic changes and left ventricular performance during high-dose oestrogen administration to male transsexuals.

Serial haemodynamic and systolic time interval measurements in 17 male transsexuals during high-dose oestrogen administration were compared with control values obtained after oestrogen withdrawal. During oestrogen treatment, cardiac output, stroke volume, plasma volume and total blood volume increased while total peripheral resistance, diastolic blood pressure and red cell mass decreased significantly. Changes in heart rate and systolic blood pressure were not significant. Despite a much higher dose of oestrogen, the haemodynamic changes observed in this study are similar in magnitude to those occurring in women taking oral contraceptives. Significant changes in systolic time intervals during oestrogen treatment were a shortened pre-ejection period (PEP) index, a prolonged left ventricular ejection time (LVET) index and a decreased PEP/LVET ratio indicating that left ventricular performance was augmented.

Value of Systolic Time Intervals in the Diagnosis of Large Patent Ductus Arteriosus in Fluid-Restricted and Mechanically Ventilated Preterm Infants

M-mode echocardiographic features suggesting a patent ductus arteriosus are based on two groups of indirect criteria: dilation of the left cardiac cavities and changes of systolic time intervals. The reliability of the first group of criteria has been questioned in fluid-limited, mechanically ventilated preterm infants. The sensitivity of the systolic time intervals in the same circumstances is investigated. Twenty-three patients with a large patent ductus arteriosus were selected. Review of their echocardiograms shows that the sensitivity of the various criteria (expressed as percentage of positivity) was as follows: inversion of the ratio of left ventricular preejection period to right ventricular preejection period, 91.3%; left ventricular preejection period to left ventricular ejection time over right ventricular preejection period to right ventricular ejection time less than 1,83%; left atrium dilation, 74%; shortening of left ventricular preejection period, 70%; dilation of left ventricular internal dimensions in diastole, 65%; increase in left atrium/aorta, 52%; and decrease of left ventricular preejection period to left ventricular ejection time, 48%. Three criteria involving time intervals (left ventricular preejection period to right ventricular preejection period, left ventricular preejection period, and left ventricular preejection period to left ventricular ejection time) had 100% specificity. The lowest specificity was found with criteria involving the left atrium (left atrial to aortic root ratio 75% and left atrium 63%). It is concluded that study of systolic time intervals is a reliable means of detecting preterm infants with hemodynamically significant left-to-right shunt through a patent ductus arteriosus even if the infants are mechanically ventilated and fluid restricted.

Dynamic effects of pericardial effusion without tamponade. Respiratory responses in the absence of pulsus paradoxus.

Fourteen patients with pericardial effusions without clinical signs of tamponade (pulsus paradoxus or other cardiac and circulatory abnormalities) showed inspiratory reductions in echocardiographic left ventricular internal diastolic diameter which correlated directly with the exaggerated respiratory changes in systolic time intervals (both pre-ejection period and left ventricular ejection time). Excessive pericardial fluid affects left ventricular function even in the absence of clinical manifestations.

Changes in systolic time intervals during physical training in patients with ischemic heart disease. Effect of beta-blockade.

Systolic time intervals (STI) were measured at rest before and after an exercise training programme in 37 patients with ischemic heart disease; 17 patients were treated with a beta-blocking drug (BB-group) and 20 were not (nBB-group). After the training period peak oxygen uptake had increased by 37% in the BB-patients and by 41% in the nBB-group. During the training period electromechanical systole (QS2) and pre-ejection period (PEP), when corrected for heart rate, shortened significantly in all 37 patients. Left ventricular ejection time (LVET) increased but when corrected for heart rate no significant changes occurred. The ratio of PEP/LVET decreased significantly. The changes in STI were similar in the patients treated with beta-blocking drugs than in those without such treatment. The changes in STI in both groups suggest that left ventricular function improves during the training period and that beta-adrenergic blockade does not alter this outcome.

CARDIAC EFFECTS OF VECURONIUM AND PANCURONIUM DURING HALOTHANE ANAESTHESIA

The cardiac effects of equipotent doses of pancuronium and vecuronium (Org NC 45) were compared in 20 patients, anaesthetized with halothane. Heart rate and arterial pressure were recorded and the systolic time intervals were evaluated from simultaneous tracings of ECG, phonocardiogram and carotid pulse curve. Pancuronium 0.08 mg kg-1 caused a significant increase in heart rate (20%), insignificant changes in arterial pressure and significant changes in systolic time intervals compatible with a minor positive inotropic action. The equipotent dose of vecuronium (0.057 mg kg-1) caused no significant changes in heart rate, arterial pressure or systolic time intervals.

Mianserin: cardiovascular effects in elderly patients.

Cardiovascular effects of the tetracyclic antidepressant drug mianserin were examined in a prospective study including ten elderly depressed patients (age 60-77 years). During 1 week on placebo and 5 weeks on mianserin, 60 mg per day, orthostatic blood pressure testing, recording of standard electrocardiogram, 24-h electrocardiographic recording and systolic time intervals were carried out along with frequent monitoring of plasma levels of mianserin (13-57 micrograms/l) and the primary metabolite desmethylmianserin (7-27 micrograms/l). Mianserin caused a significant increase in orthostatic systolic blood pressure drop, and this correlated well with the plasma mianserin levels (rs = 0.70). There were no significant changes in supine blood pressure or in orthostatic changes in heart rate. No cardiac conduction disturbances or arrhythmias were provoked, but mianserin caused changes in systolic time intervals indicating impairment of left ventricular contractility and performance. Like tricyclic antidepressants mianserin should thus be used with caution in patients with latent or overt cardiovascular disease.

Changes of systolic time intervals and ejection fraction during dynamic exercise in essential hypertension

Changes of systolic time intervals and ejection fraction during dynamic exercise in essential hypertension

Postextrasystolic changes in systolic time intervals in the assessment of hypertrophic cardiomyopathy.

To determine if postextrasystolic changes in systolic time intervals can be used to estimate the severity of resting or provocable left ventricular outflow pressure gradient, we studied the cardiac catheterisation records of 42 patients with hypertrophic cardiomyopathy looking for instances of a single premature beat preceded by a control sinus beat and followed by a postpremature sinus beat. There were 75 such instances in 25 patients. In comparison to the control beat, the pre-ejection period in the postpremature beat was shorter by deltaPEP = -20 +/- 11 ms in 73 of 75 instances, and remained unchanged in two. The ejection time in the postpremature beat was invariably longer by deltaET = 37 +/- 20 ms (range: 10 to 85 ms) and the pre-ejection period/ejection time ratio lower than control by delta(PEP/ET) = -0 . 10 +/- 0 . 05 (range: -0 . 01 to -0 . 25). Total electromechanical systole in the postpremature beat was shorter (11/75), the same (10/75), or longer (53/75) than in the control beat, the overall change being deltaEMS = -18 +/- 22 ms. Both deltaPEP and delta(PEP/ET) correlated poorly with the systolic peak left ventricular-aortic pressure gradient in either the control beat (Gc) or the postpremature beat (Gx), and also with the change in gradient (delta G) from the control to the postpremature beat. In contrast, significant linear correlations were found between delta EMS and either Gc, Gx, or delta G; and also between deltaET and either Gc, Gx, or deltaG. Since internal and external measurements of ejection time are known to be almost identical, the regression equation (deltaG = 1 . 65 delgaET -9) relating deltaET and deltaG should be useful for the non-invasive assessment of the magnitude of provocable left ventricular outflow pressure gradient in patients with hypertrophic cardiomyopathy with spontaneous or externally-induced premature beats.

Changes of systolic time intervals in asymptomatic patients with primary hyperlipoproteinemia

Previous studies have focused on the usefulness of systolic time intervals to assess changes of myocardial function. In a recent report, hyperlipoproteinemia (HLP) was shown to induce early signs of vascular disease in asymptomatic subjects. By means systolic time intervals (STI) we studied left ventricular function in normal subjects and asymptomatic patients with HLP, who showed normal response to exercise on a bicycle ergometer. The results showed mean values of STI for the population in the normal range, according to standards accepted in North American reports. Different values of STI were found when we compared the data of controls with the STI of HLP patients with higher values of PEPI and PEP/LVET and lower values of LVETI in HLP patients. These results suggest that hyperlipoproteinemia affects STI in asymptomatic patients, probably as a sign of early impairment of left myocardial function.

Skeletal muscle digoxin concentration during digitalization and during withdrawal of digoxin treatment.

Blood samples and skeletal muscle biopsies (m. quadriceps femoris, vastus lateralis) were taken from 15 patients during digitalization or during withdrawal of digoxin treatment for analysis of serum and skeletal muscle digoxin concentrations. A percutaneous needle biopsy technique was used for muscle sampling and digoxin was analysed by radioimmunoassay. During "slow" digitalization with 0.25 mg digoxin daily the skeletal muscle digoxin concentrations after 2 and 4 days were 45% (range 19%--62%; n = 3) and 78% (range 56%--92%; n= 3) respectively, of the steady state concentration (defined as the digoxin concentration after 25--40 days of treatment). After 9 and 11 days of treatment the skeletal muscle digoxin concentrations were 106% (range 84%--133%; n = 5) and 116% (range 72%--164%; n = 3) respectively, of the steady state concentration. A doubling of the digoxin dose gave a proportional increase in skeletal muscle digoxin concentration (three patients). The magnitude of the estimated half-life of skeletal muscle digoxin was the same as previously reportedly in healthy subjects. No significant correlations were found between changes in systolic time intervals and steady state serum or skeletal muscle digoxin concentrations.

Correlation between changes in systolic time intervals and left ventricular end-diastolic diameter after preload reduction. Non-invasive monitoring of pharmacological intervention.

In order to measure the effect of a decrease in preload on systolic time intervals and left ventricular end-diastolic diameter (LVEDD) measured by echocardiography, eight healthy young subjects were given 40 mg frusemide intravenously. The pre-ejection period index (PEPI) increased and the left ventricular end-diastolic diameter decreased. A correlation between delta PEPI and delta LVEDD was shown. Using changes in systolic time intervals in the evaluation of changes in contractility it is important to correct for changes in preload. For normal subjects it is suggested that the relation between delta PEPI and delta LVEDD as a percentage of the mean values should be used for this correction. A method is suggested for estimating the changes in pre-ejection period index induced by changes in left ventricular end-diastolic diameter.

Growth patterns of cardiac structures and changes in systolic time intervals in the newborn and infant. A longitudinal echocardiographic study.

A longitudinal study was undertaken in 21 newborns to determine cardiac growth pattern by echocardiography over the course of the first year of life. Most cardiac structures increased in size as a linear function of age and weight; however, the right ventricular end-diastolic diameter remained unchanged so that the RV/LV ratio decreased as a parabolic function of age. Left and right ventricular systolic time intervals (RVSTI, LVSTI) after birth were also studied. The ratio of left ventricular preejection period (LVPEP) to left ventricular ejection time (LVET) decreased markedly immediately after birth and subsequently remained at a constant mean value (0.30 +/- 0.04) for the rest of the study period. Right ventricular systolic time interval ratios (RVPEP/RVET) decreased rapidly and significantly during the first day of life (from a mean value of 0.39 +/- 0.08 in the first 24 hours to 0.28 +/- 0.05 on the 6th day of life). Constant values of 0.24 +/- 0.03 were found from the 3rd month of life onwards. The decrease in RVPEP/RVET in the first days of life followed a parabolic function reflecting the physiological decrease of pulmonary vascular resistance after birth.

Systolic time interval as index of schedule--dependent doxorubicin cardiotoxicity in patients with acute myelogenous leukaemia.

The ratio of the pre-ejection period to the left ventricular ejection time (PEP:LVET) was measured in two groups of patients with acute myeloblastic leukaemia (AML) receiving the anthracycline antibiotic doxorubicin (DXR). Patients receiving high doses of DXR per course (about 90 mg/m2) showed a significant increase in the PEP:LVET ratio irrespective of the total cumulative dose. At a lower dose per course (less than 50mg/m2) only patients who had a total cumulative dose of over 450 mg/m2 showed significant increases in ratio. ECG changes were seen in both groups of patients but did not correlate significantly with the dosage. These findings, which suggest that DXR cardiotoxicity is schedule dependent, are important in the design of schedules of DXR for treating cancer and in interpreting the changes in systolic time intervals (STIs) observed with different schedules. Measurement of the STI is a simple and convenient method of assessing DXR cardiotoxicity. While a total DXR dose of 550 mg/m2 should not normally be exceeded, by carefully monitoring the STI the recommended total dose may be exceeded safely in selected patients.