Pre-ejection Period/left Ventricular Ejection Time Research Articles

Myocardial effects of isoflurane in healthy infants and small children

In paediatric healthy patients and in real peroperative conditions, the cardiovascular effects of isoflurane have been poorly described. We have evaluated the myocardial effects of 1% end-expired concentration (EEC) of isoflurane in 25 healthy infants or small children undergoing superficial surgical therapy for small burns with a continuous aortic blood flow echo-Doppler device. Aortic blood flow (ABF) was measured with a small oesophageal probe specially designed for infants. The aortic flowmeter was connected with satellite devices to visualize the haemodynamic profile variations during the isoflurane inhalation period. Isoflurane significantly decreased ABF and increased pre-ejection period/left ventricular ejection time (PEP/LVET), when compared with control values previously recorded 5 min after induction with halothane-fentanyl and atracurium (respectively, 80 +/- 7%, mean +/- SD; P < 0.001 and 111 +/- 11%; P = 0.017, 5 min after EEC of isoflurane reached 1%, then respectively, 75 +/- 12%; P < 0.001 and 119 +/- 16%; P < 0.001, at the end of the isoflurane inhalation period). These variations reversed to a great extent when isoflurane was switched off (97 +/- 17% for ABF; P = 0.08 and 105 +/- 12% for PEP/LVET; P = 0.75). Among the usual parameters, 1% EEC of isoflurane caused no significant changes in heart rate, moderately decreased mean arterial pressure (successively, 88 +/- 12%; P = 0.045 and 87 +/- 19%; P = 0.049), but belatedly decreased end-tidal CO2 pressure (87 +/- 11% at the end of the inhalation period (P < 0.001) which persisted 5 min after isoflurane was turned off (90 +/- 11%; P < 0.001)). These findings suggest that isoflurane can transiently depress cardiac function in healthy infants.

Effects of Radix Astragali on left ventricular function and oxygen free radicals in acute myocardial infarction patients and its mechanism of cardiotonic action

Dynamic observations for 4 weeks were made on left ventricular function and oxygen free radicals (OFR) in 43 patients who suffered the first attack of acute myocardial infarction and was hospitalized in Coronary Care Unit within 36 hours. The results showed that Radix Astragali (RA) could strenthen the left ventricular function and had an effect of scavenging OFR. After administration of RA, the ratio of pre-ejection period/left ventricular ejection time (PEP/LVET) was decreased, the superoxide dismutase (SOD) activities of erythrocytes were increased, and the lipid peroxidation (LPO) concentration of plasma was reduced. There was a significant difference between the RA group and the control group in the parameters mentioned above. The study demonstrated that the PEP/LVET ratio was closely correlated with SOD and LPO. It suggested that the scavenging effect of RA on OFR was one of its mechanisms of cardiotonic action.

Acute Hemodynamic Effects of Medetomidine and Clonidine in Healthy Volunteers: A Noninvasive Echocardiographic Study

Single intravenous (i.v.) doses of 4(5)-[1-(2,3-dimethylphenyl)ethyl]imidazole, medetomidine (MED), (25, 50, and 100 micrograms) and clonidine (CLO 200 micrograms) were administered to five healthy male volunteers in a randomized, double-blind, placebo-controlled, multiple cross-over study. The hemodynamic effects of the drugs were determined by a two-dimension Doppler-echocardiographic method. Blood pressure (BP) and heart rate (HR) were monitored noninvasively. Cardiac output (CO) was maximally reduced by 23% after 100 micrograms MED and 200 micrograms CLO. Dose-related decreases were observed in systolic BP (SBP) and diastolic BP (DBP) and HR. Maximal reductions were 18 and 11 mm Hg and 11 beats/min after 100 micrograms MED, and 18 and 13 mm Hg and 12 beats/min after CLO. Calculated total peripheral resistance (TPR) and the PR interval on ECG remained unchanged. Ejection fraction (EF) and stroke volume (SV) were not significantly affected by either drug, but mean circumferential fiber shortening velocity (VCF) and the preejection period/left ventricular ejection time (PEP/LVET) ratio indicated a tendency to slightly decreased myocardial performance. We conclude that the new selective alpha 2-adrenoceptor agonist, MED, resembles CLO in its acute hemodynamic actions in healthy humans.

The effects of probucol on [formula omitted] relation and systolic time intervals

The QT, QTc, QS 2 intervals, pre-ejection period-left ventricular ejection time ratios and serum lipoprotein levels were measured in 8 patients with primary hypercholesterolemia before and after a 3-month therapy with probucol, 1 g/day. Both QT and QTc intervals increased significantly, whereas no significant changes were observed between the pre- and post-treatment QT QS 2 and pre-ejection period-left ventricular ejection time ratios. These results help to explain why treatment with probucol, while effecting a prolongation of the QTc interval, does not result in serious arrhythmias in man.

Response of the left ventricle in idiopathic dilated cardiomyopathy to postextrasystolic potentiation

The effectiveness of postextrasystolic potentiation (PESP) was assessed to detect residual function of the left ventricle in seven patients with idiopathic diated cardiomyopathy (IDC). The postextrasystolic changes in the aortic pressure pulse, global left ventricular function, and quantitative regional left ventricular wall motion were investigated. PESP caused an increase in the peak systolic aortic pressure (116 ± 17 to 130 ± 25 mm Hg, p < 0.01), a decrease in the peak diastolic aortic pressure (74 ± 12 to 61 ± 11 mm Hg, p < 0.001), a decrease in preejection period/left ventricular ejection time (PEPLVET) ratio (0.637 ± 0.136 to 0.457 ± 0.097, p < 0.001), and an increase in the global left ventricular ejection fraction (LVEF) (0.26 ± 0.09 to 0.40 ± 0.12, p < 0.01). Postextrasystolic changes in LVEF were inversely related to changes in PEPLVET (r = −0.76, p < 0.05). The postextrasystolic patterns of the regional wall motion of the left ventricle were different in each patient. The results of this study suggest that residual left ventricular function can be detected in patients with IDC by their response to PESP.

Abnormal systolic time intervals in obesity and their relationship with the amount of overweight

We studied 17 severely obese subjects (age range 26 to 42 years), without hypertension, diabetes mellitus, angina, or clinical signs of heart failure or respiratory disease, and 16 age-matched control subjects. X-teleroentgenographic findings (transverse cardiac diameter and cardiothoracic ratio), blood pressure, and mechanocardiographic parameters were analyzed in both groups. By means of conventional simultaneous recordings of ECG, phonocardiogram, and carotid pulse (100 mm/sec), systolic time intervals were calculated as mean values from 10 beats in the morning. The following comparisons were made by means of analysis of variance: heart rate, preejection period (PEP), rate-corrected PEPI (PEPI), left ventricular ejection time (LVET), and QS 2 interval (QS 2); the latter two were both corrected for heart rate, respectively, as LVETI and QS 2I and the PEP LVET ratio. Abnormal x-ray data were shown in the obese group along with higher values for heart rate, PEP, PEPI, and PEP LVET and a shorter LVETI; there were no differences in QS 2I or blood pressure. There was a correlation between the amount of overweight and, respectively, transverse cardiac diameter ( r = 0.84), heart rate ( r = 0.69), PEP ( r = 0.49), PEPI ( r = 0.59), LVETI ( r = −0.61), and PEP LVET ratio ( r = 0.72). A correlation was also found between transverse cardiac diameter and PEP LVET ( r = 0.67). We conclude, therefore, that abnormalities in the mechanocardiographic parameters are related to cardiac enlargement, suggesting a preclinical cardiac dysfunction secondary to chronic cardiocirculatory overload in severe obesity. Thus systolic time intervals appear to be affected by preclinical abnormalities of cardiac performance in these subjects.

Noninvasive Assessment of Left Ventricular Performance After Administration of Bisoprolol

The effects of single doses of 10, 20, and 40 mg of bisoprolol on left ventricular performance were assessed by left ventricular systolic time interval measurements, echocardiographic measurements, and exercise stress tests in patients with mild to moderate arterial hypertension. Bisoprolol caused a significant, dose-dependent fall in systolic and diastolic blood pressure and heart rate, at rest and under exercise stress test. Left ventricular systolic time intervals were prolonged at the higher doses, but pre-ejection period/left ventricular ejection time (PEP/LVET) ratio, as an indicator for left ventricular performance, remained unchanged. Left ventricular echocardiographic dimensions increased significantly, but shortening fraction was not altered. We conclude that 10-40 mg bisoprolol, apart from the blockade of beta 1-adrenoceptors, does not affect left ventricular cardiac function.

Positive inotropic effects of an ACTH analogue (ACTH 1-17) on myocardial performance.

The aim of the present investigation was to study the effects of a single 100-micrograms i.v. administration of the synthetic heptadecapeptide [beta-Ala1-Lys17]ACTH1-17-4-amino-N-butylamide (ACTH 1-17) on the left ventricular performance. The systolic time intervals (STI) were recorded in 20 healthy adult young subjects (10 treated with ACTH 1-17 and 10 receiving placebo) before as well as 20, 40, 60 and 80 min after the i.v. ACTH 1-17 or placebo infusion. The STI were recorded immediately after blood withdrawal for measuring cortisol, aldosterone, adrenaline and noradrenaline plasma levels. A highly significant statistical difference was demonstrated for preejection period (PEP) and preejection period/left ventricular ejection time (PEP/LVET) ratio between subjects treated with ACTH 1-17 and subjects receiving placebo. As expected, a significant increase of cortisol and aldosterone plasma levels was observed in subjects treated with ACTH 1-17. The difference of adrenaline and noradrenaline plasma levels was statistically highly significant between subjects treated with ACTH 1-17 and those receiving placebo. The lack of increase in PEP and PEP/LVET ratio recorded in subjects treated with ACTH 1-17 is consistent with an increased left ventricular contractile performance. An increased plasma catecholamine release is postulated as the mechanism of this improvement.

Left ventricular function at high altitude examined by systolic time intervals and M-mode echocardiography

To better understand the effects of high-altitude hypoxia on cardiac performance, healthy lowlandresiding volunteers were studied in 2 groups: 10 subjects after acute ascent to 12,500 ft (3,810 m) (acute group) and 9 subjects after chronic exposure for 6 weeks to 17,600 ft (5,365 m) and 11,000 ft (3,353 m) (chronic group). Systolic time intervals and M-mode echocardiograms were recorded at low and high altitudes. Heart rate was 21% greater at high altitude for all subjects. Preejection period/left ventricular ejection time (PEP/LVET) increased by 16% in the acute group and by 22% in the chronic group. Heart size was smaller at high altitude in both groups, with left atrial and left ventricular (LV) diameters decreasing by 10 to 12%. These changes were statistically significant (p ≤ 0.01). Despite the increase in PEP/LVET, echocardiographic measurements of LV function (percent fractional shortening and mean normalized velocity of circumferential fiber shortening) remained normal. LV isovolumic contraction time was shorter at high altitude, suggesting heightened, rather than depressed, contractility. LV function does not appear to deteriorate at high altitude. Alterations in systolic time intervals probably result from decreased preload, as reflected by smaller heart size, rather than from heart failure or depressed LV contractility.

Systolic time intervals in children with heart disease.

Of the systolic time intervals, the preejection period is known to correlate well with invasively measured isometric contraction time, and increase of the quotient preejection period/left ventricular ejection time (PEP/LVET) is considered to be of a good indicator of left ventricular failure. The different systolic time intervals have been recorded from the carotid pulse curve from 40 normal children, 20 aged five and 20 aged ten years. Their PEP/LVET was 0.31 +/- 0.04. Seventy-eight children with different heart diseases were then investigated. In patients with congenital total heart block or extrasystoles, there was a negative correlation between PEP/LVET and the R-R interval, in accordance with the Frank-Starling law. In patients with ventricular septal defects PEP/LVET differentiates between small and large shunts; the increased PEP/LVET of the latter normalizes after operation. The increased PEP/RVET of children with transposition of the great arteries is an expression of the inadequacy of the right ventricle as a systemic chamber. In aortic stenosis "normalization" of a previously decreased PEP/LVET may indicate early left ventricular failure. In primary myocardial disease registration of the systolic time intervals enables us to follow the left ventricular function more closely than is possible with invasive techniques.

A computerized system for monitoring systolic time intervals from esophageal accelerograms

An automated microcomputer system for monitoring heart rate and systolic time intervals (STI)—preejection period (PEP), left ventricular ejection time (LVET), and PEP LVET —was implemented. The system, employing esophageal accelerometry, is economical and simple to operate. Being light and compact, it is therefore portable. The accuracy and reliability are no less than considerably more costly systems. The set of systolic time intervals can be measured and output in 6 sec. The system offers the advantage of monitoring STI in a larger number of surgical patients than do traditional systems due to its esophageal transducer.

Abbreviation of systolic time intervals in acute mitral regurgitation: Effect of prosthetic mitral valve replacement

Systolic time intervals were measured in 26 patients with mitral regurgitation (acute in 14 and chronic in 12). In 13 of these patients (7 with acute and 6 with chronic mitral regurgitation) systolic time intervals were also measured after mitral valve replacement. Total electromechanical systole corrected for heart rate (Q-S 2I) was of much shorter duration in the group with acute mitral regurgitation (472 ± 9 msec [mean ± standard error of the mean]) than in the group with chronic mitral regurgitation (516 ± 4.6 msec, P < 0.01). Before operation, the ratio of the preejection period (PEP) to left ventricular ejection time (LVET) and the angiographic ejection fraction did not differ in the groups with acute and chronic mitral regurgitation. The correlation between the PEP LVET ratio and ejection fraction was r = − 0.84, P < 0.01. Two weeks after operation, the PEP LVET ratio increased in all patients, but the increase was greater in those with lower preoperative values for this ratio. The mechanism of the early postoperative increase in the PEP LVET ratio is not clear, but serial studies performed over 6 months showed a return toward the preoperative value. It is concluded that preoperative systolic time intervals are useful for assessing left ventricular performance in all types of mitral regurgitation, but are especially useful for distinguishing between the acute and chronic varieties.

Erythrityl tetranitrate

The effects of sustained preload reduction have been demonstrated for several nitrates but not for erythrityl titranitrate. In seven patients with coronary heart disease, a randomized double-blind crossover clinical trial showed that chewable erthrityl tetranitrate, 10 mg, produced significant changes in systolic time intervals consistent with preload reduction and lasting for at least four hours. As compared with placebo, ejection time index (ETI) fell and remained significantly low between 6 and 90 minutes after administration, and pre-ejection period (PEP), isovolumic contraction time IVCT), and pre-ejection period/left ventricular ejection time (PEP/LVET) rose and remained significantly increased between 22 minutes and the four-hour endpoint. We conclude that erythrityl tetranitrate is a physiologically effective long-acting agents in patients with coronary heart disease.

Effects of postextrasystolic potentiation on systolic time intervals

The changes in systolic time intervals associated with postextrasystolic potentiation were studied in 48 patients whose left ventricular function was categorized angiographlcally into four groups—normal function (I) and mlld (II), moderate (III) and severe (IV) left ventricular dysfunction. Postectopic potentiation in all groups caused a decrease in preejection period/left ventricular ejection time (PEP/LVET) ratio. The greatest potentiation and decreases in PEP/LVET ratio were noted in beats where the difference in compensatory pause and coupling interval (both expressed as percent of basic cycle length [CP percent — CI percent]) exceeded 40. The decrease in the ratio was least in the normal subjects (Group I) and maximal in Group IV patients. The pattern of response of the rate-corrected left ventricular ejection time and preejectlon period was also different at the four levels of ventricular function. Marked shortening of ejection time with minimal shortening of preejection period occurred in Group I, but in Group IV patients there was marked shortening of preejection period and minimal shortening of ejection time. An intermediate response was seen in Group II and III patients. The amount of shortening of ejection time exceeded that of preejection period in Group II patients; the reverse was true in Group III patients. The group responses differed with a significance of 2 P <0.001 except when Group II was compared with Group III, when the significance was 2 P <0.025. Thus, measurement of changes in systolic time intervals associated with postextrasystolic potentiation is of value as a noninvasive means of assessing resting left ventricular function.

Influence of heart rate increase on uncorrected pre-ejection period/left ventricular ejection time (PEP/LVET) ratio in normal individuals.

In 26 normal volunteers, increase in heart rate from mean 73-94 +/- 1-97 to 103-61 +/- 2-72/min, by either intravenous atropine administration or rapid right atrial pacing, produced definite changes in the uncorrected systolic time intervals. As expected, total electromechanical systole (QS2) and left ventricular ejection time (LVET) were shortened, while the pre-ejection period (PEP) was unaffected. There was a consistent and significant increase of the PEP/LVET ratio (P less than 0-001). It is postulated that when this ratio is taken to express left ventricular contractility, it should probably be corrected for heart rate. Appropriate regression equations for such a correction were calculated (PEP/LVET=0-249 + 0-0168 HR).

A comparative study of enflurane and halothane using systolic time intervals.

The effects of enflurane and halothane anesthesia on systolic time intervals were studied in 12 healthy patients. Cardiovascular measurements were made at equipotent levels of anesthesia: enflurane 1.23% end-tidal and halothane 0.65% end-tidal. These agents were studied first with 50% N2O and then without N2O. Systolic, diastolic, and mean arterial blood pressure were decreased more by enflurane than by halothane (p less than 0.05). However, halothane caused significantly more myocardial depression than enflurane, as indicated by a larger preejection period (PEP) and preejection period/left ventricular ejection time (PEP/LVET) and a smaller 1/PEP2 and ejection fraction. When N2O was discontinued, both agents increased PEP and PEP/LVET and decreased 1/PEP2 and the ejection fraction.

Left ventricular abnormalities in prolapsed mitral leaflet syndrome. Review of eighty-seven cases.

Eighty-seven patients with proven mitral leaflet prolapse were studied emphasizing cardiodynamics and left ventricular asynergy. Significant associated features were female preponderance (83%), skeletal anomalies (pectus excavatum, straight back, scoliosis, narrow antero-posterior diameter of the chest), and anomalous coronary arteries (cork-screw patterns, short left main coronary artery, anomalous origin of the coronary arteries). Prolapse of the tricuspid leaflets was found in 15 (54%) who had right ventriculography. Five types of abnormal left ventricular systolic contraction patterns were seen in 82% of the cases and these were categorized as: 1) "ballerina foot" pattern (vigorous posteromedial contraction with anterior convexity), 2) "hour glass" pattern (vigorous ring-like contraction involving the middle portion of the left ventricle), 3) inadequate long axis shortening, 4) posterior akinesis, and 5) cavity obliteration pattern. The over-all left ventricular performance was normal generally, as indicated by normal values for functional parameters including left ventricular end-diastolic pressure, cardiac index, ejection fraction, contractility index (stroke work per end-diastolic volume) and pre-ejection period/left ventricular ejection time (PEP/LVET). The myocardial component of the syndrome of prolapsed mitral (and/or tricuspid) leaflets is expressed as asynergistic patterns of ventricular motion and usually does not impair over-all cardiac dynamics.

Effects of normal breathing and expiratory apnea on duration of the phases of cardiac systole

The phases of left ventricular systole were measured in normal inspiration and expiration and during expiratory apnea. There were no significant differences in heart rate (HR) among the three respiratory states. By contrast, pre-ejection period (PEP), left ventricular ejection time (LVET), ejection time index (ETI), and PEP LVET showed highly significant differences. Both the respiratory frequency (rr) and the ratio HR rr had negligible independent correlations with PEP, LEET, ETI, and PEP LVET . The highly significant differences in PEP, LVET, ETI, and PEP LVET among the respiratory states indicated real trends (p < 0.01) or (p < 0.001), with values during expiratory apnea resembling those during inspiration. Functionally optimal values were obtained during phasic expiration.