Left Ventricular Ejection Duration Research Articles

Accurate end systole detection in dicrotic notch-less arterial pressure waveforms.

Identification of end systole is often necessary when studying events specific to systole or diastole, for example, models that estimate cardiac function and systolic time intervals like left ventricular ejection duration. In proximal arterial pressure waveforms, such as from the aorta, the dicrotic notch marks this transition from systole to diastole. However, distal arterial pressure measures are more common in a clinical setting, typically containing no dicrotic notch. This study defines a new end systole detection algorithm, for dicrotic notch-less arterial waveforms. The new algorithm utilises the beta distribution probability density function as a weighting function, which is adaptive based on previous heartbeats end systole locations. Its accuracy is compared with an existing end systole estimation method, on dicrotic notch-less distal pressure waveforms. Because there are no dicrotic notches defining end systole, validating which method performed better is more difficult. Thus, a validation method is developed using dicrotic notch locations from simultaneously measured aortic pressure, forward projected by pulse transit time (PTT) to the more distal pressure signal. Systolic durations, estimated by each of the end systole estimates, are then compared to the validation systolic duration provided by the PTT based end systole point. Data comes from ten pigs, across two protocols testing the algorithms under different hemodynamic states. The resulting mean difference ± limits of agreement between measured and estimated systolic duration, of [Formula: see text] versus [Formula: see text], for the new and existing algorithms respectively, indicate the new algorithms superiority.

The Effect of Lower Body Positive Pressure on Left Ventricular Ejection Duration in Patients With Heart Failure.

Lower body positive pressure (LBPP) treadmill activity might benefit patients with heart failure (HF). To determine the short-term effects of LBPP on left ventricular (LV) function in HF patients, LV ejection duration (ED), a measure of systolic function was prospectively assessed in 30 men with stable HF with LV ejection fraction ≤ 40% and 50 healthy men (N). Baseline measurements (100% body weight), including blood pressure (BP), heart rate (HR) and LVED, obtained via radial artery applanation tonometry, were recorded after 2 minutes of standing on weight support treadmill and after LBPP achieving reductions of 25%, 50%, and 75% of body weight in random sequence. Baseline, HR, and LVED (251 ± 5 vs 264 ± 4 ms; P = .035) were lower in the HF group. The LBPP lowered HR more (14% vs 6%, P = .009) and increased LVED more (15% ± 7% vs 10% ± 6%; P = .004) in N versus HF. Neither group had changes (Δ) in BP. On generalized linear regression, the 2 groups showed different responses (P < .001). Multivariate analysis showed %ΔHR (P < .001) and HF (P = .026) were predictive of ΔED (r 2 = 0.44; P < .001). In conclusion, progressive LBPP increases LVED in a step-wise manner in N and HF patients independent of HR lowering. The ΔLVED is less marked in patients with HF.

Gender differences of aortic wave reflection and influence of menopause on central blood pressure in patients with arterial hypertension

BackgroundEvidences suggest that central hemodynamics indexes are independent predictors of future cardiovascular events and all-cause mortality. Multiple factors have been pointed to have potential influence on central aortic function: height, heart rate, left ventricular ejection duration and blood pressure level. Data related to the influence of gender and postmenopausal status on aortic waveform reflection is scarce. We aim to evaluate the impact of gender and menopause on central blood pressure of hypertensive patients.MethodsIn a cross sectional study 122 hypertensive patients (52 men and 70 women) were studied. Hypertension was defined as blood pressure (BP) levels ≥140/90 mmHg or use of antihypertensive drugs. Central arterial pressure, augmentation index (AIx) and augmentation index normalized to 75 bpm (AIx75) were obtained using applanation tonometry. Menopause and postmenopause history were accessed by a direct series of questions. Postmenopause was defined as at least one year since last menstruation. Patients were paired by age, gender and menopausal status, and the data were compared considering gender and menopausal status.ResultsHeight and weight were significantly lower in women than in men at the same age. Conversely, AIx (32.7 ± 9.8% vs. 20.1 ± 11.7%, p < 0.01), AIx75 (29.6 ± 6.7% vs. 18.3 ± 9.4%, p < 0.01) and central systolic blood pressure (136 ± 30 vs. 125 ± 23 mmHg, p = 0.03) were higher in women than men. The menopausal women (mean age of menopause = 48 years) had the worst indexes of aortic wave reflection, compared to men at the same age and younger women.ConclusionHypertensive women had both higher reflected aortic pressure waveform and central blood pressure indexes than hypertensive men, and these findings were worsened by the menopausal status.

Early sex differences in central arterial wave reflection are mediated by different timing of forward and reflected pressure waves.

Non-invasive assessment of central arterial pulse wave augmentation has been proved to be useful in predicting cardiovascular adverse events. Previous studies have shown that pre-pubescent girls had greater central augmentation pressure compared with height-matched boys. This study sought to investigate which factors contribute to the body height-independent sexual differences in central arterial wave reflection observed in childhood. This cross-sectional study involved 819 children and adolescents (6-18years of age) of both sexes. Phenotypes of central haemodynamic were obtained by radial applanation tonometry. Heart rate corrected augmentation index (Aix@75) was greater in girls compared with boys (2.9±10.7 vs -1.7±12.9%, P<.001) as well as the central augmented pressure (cAP; 1.3±3.3 vs 0.1±3.8mmHg, P<.001), even adjusting for age, heart rate and body height. Left ventricular ejection duration (ED) was longer (320±26 vs 314±24ms, P=.004) and time to inflection point (Tr) was shorter in girls (139±14 vs 141±21ms, P=.014). The reduction of Aix@75 with increasing body height was steeper in boys (-0.499±0.030 vs -0.428±0.036%/cm, P<.001) as well as the reduction of cAP with increasing body height (-0.108±0.010 vs -0.066±0.013mmHg/cm, P<.001). Body height-independent sexual differences observed in the pulse wave reflection indices from early adolescence were mediated by different timing of forward and reflected pressure waves.

Abstract P315: Gender Differences of Aortic Wave Reflection and Influence of Menopause on Central Blood Pressure in Patients With Arterial Hypertension

Background: Evidences suggest that central hemodynamics indexes are independent predictors of future cardiovascular events and all-cause mortality. Multiple factors have been pointed to have potential influence on central aortic function: height, heart rate, left ventricular ejection duration and blood pressure level. Data related to the influence of gender and postmenopausal status on aortic wave form reflection is scarce. Methods: In a cross sectional study, 122 hypertensive patients (52 men and 70 women) were studied. Hypertension was defined as blood pressure (BP) levels ≥140/90 mmHg or use of antihypertensive drugs. Central arterial pressure, augmentation index (AIx) and augmentation index normalized to 75bpm (Alx75) were obtained using applanation tonometry. Menopause and postmenopause history were accessed by a direct questionnaire. Postmenopause was defined as at least one year since last menstruation. Patients were paired by age, gender and menopausal status and 4 groups were compared: group 1 (young men, ≤ 48y), group 2 (young women, ≤4 8y), group 3 (older men, &gt; 48y) and group 4 (older women, &gt; 48y). Results: Height and weight were significantly lower in women than in men at the same age. Conversely, Alx (32.7±9.8% vs. 20.1±11.7%, p&lt;0.01), Alx75 (29.6±6.7% vs. 18.3±9.4%, p&lt;0.01) and central systolic blood pressure (136±30 vs. 125±23 mmHg, p=0.03) were higher in women than men. The menopausal women had the worst indexes of aortic wave reflection. Conclusion: Women patients had both higher reflected aortic pressure wave form and central blood pressure indexes and these findings were worsened by the menopausal status.

СENTRAL AORTIC PRESSURE AND AUGMENTATION INDEX IN YOUNG ADULTS WITH REGARD TO CARDIOVASCULAR RISK FACTORS

O bjective. To estimate central aortic blood pressure (BP) and index of augmentation in young people, taking into account the presence of risk factors (RF), during preventive medical examination. Desig n an d methods. Altogether 78 students of 3–4 years, aged 19–23 years old have been surveyed within the framework of the regular medical examinations, at the Center of Students’ Health, Stavropol State Medical University, as a part of the project “University is the territory of health”. Besides RF assessment, central aortic pressure was evaluated by oscillometric method (BPLab, “Peter Telegin”,Novosibirsk,Russia; Vasotens Office). In addition to common peripheral BP parameters, this technology provides measurements of systolic BP aortic (SYSао), diastolic BP aortic (DIAао), pulse BP aortic (PPао), average BP aortic (ABPао), left ventricular ejection duration (ED), augmentation index in aorta (AIxао), pulse pressure amplification (PPA) and subendocardial viability ratio (SEVR). Surveyed students were distributed into two groups: first group — without RF (control group), and second group — with RF (main group). For automatic tubulation of all parameters we used the operational system BPStat ® version 05.00.04 (“Petr Telegin”). For statistical data processing program “Statistica8” was used. R esults. At young age RF are associated with the increase of both peripheral and aortic BP, especially systolic and pulse ВР, as well as augmentation index of central ВР. In students RF are associated with the increase of aortic BP (isolated central or masked hypertension/prehypertensionwith the simultaneous increase of both peripheral and aortic BP). The frequency of isolated increase of peripheral BP among students with RF is similar to that in students without RF. C onclusions. Thus, planimetric analysis of central pulse wave in young people allows to define various mechanisms leading to the early BP increase. These data enable differentiated premorbid diagnostics of hemodynamic status in young adults with cardiovascular RF. This approach will contribute to the more individualized preventive measures in young population.

Reproducibility and variability in the assessment of color-coded tissue velocity imaging of the fetal myocardium¬

Objective : The introduction of color-coded tissue velocity imaging (TVI) in fetal medicine is quite recent, and as this method is presently evaluated and developed in regard to diagnostic precision it is of outmost importance to evaluate the reproducibility for adequate clinical use. In this study, reproducibility and intra- and inter-observer variability was assessed for offline analysis as well as echocardiography investigations. Also, we evaluated the importance of exact placement of the region of interest (ROI). Methods : TVI recordings from 21 fetuses, at a gestational age of 27 to 41 weeks, were acquired at 208-239 frames/s for subsequent offline analysis. All recordings were performed with the transducer positioned to provide an apical four-chamber view and the myocardial velocity data was obtained from basal inferoseptum. The data set was analyzed according to Bland-Altman and reproducibility was expressed as the standard error of a single determination, estimated from duplicate determinations in percentage of the total. Results : The variation of reproducibility for the echocardiography investigation ranged from 2.0% to 9.8%. The duration of left ventricular ejection, and the peak velocities of early diastolic filling and atrial contraction being the most robust events measured. The variation of inter-observer variability for the echocardiography investigation ranged from 1.5% to 8.4%, and the variation of intra- and inter-observer variability for the offline analysis ranged from 1.2% to 10.4%. Least robust were the events of shortest duration, including isovolumetric contraction and relaxation. Conclusion : We believe that TVI measurements of the fetal myocardium could be performed in the clinical routine with acceptable reproducibility.

Influence of Aortic Pressure Wave Components Determined Noninvasively on Myocardial Oxygen Demand in Men and Women

Myocardial oxygen consumption is increased by arterial stiffening. It is not known precisely how. This study aimed to evaluate the role of the incident and reflected pressure wave in raising myocardial oxygen demand. Central (aortic) pressure waveforms were generated from radial waveforms using a generalized transfer function in 1628 cardiology outpatients (1038 males and 590 females). Aortic waveforms were used to derive measures of incident and reflected waves, as well as to measure mean central systolic pressure (an indicator of systolic ventricular load), left ventricular ejection duration, and tension time index (a surrogate of myocardial oxygen demand) using validated techniques. Incident and reflected waves were measured using the conventional and an alternative method (aortic flow triangulation). Relationships were tested before and after correction for age, height, weight, heart rate, and mean arterial pressure using simple and multivariate linear regression models. Analyses were conducted separately by gender. In both genders (according to conventional or alternative methods of wave measurement), both the incident and reflected wave were strong predictors of tension time index (P<0.001). Both pressure waves raised the mean central systolic pressure (P<0.001). The reflected wave (P<0.001), unlike the incident wave (P>0.05), was also associated with a longer cardiac ejection duration. Tension time index (P<0.0001), mean central systolic pressure (P<0.001), and ejection duration (P<0.0001) were greater in women. Changes in arterial properties alter the nature of pressure wave propagation and predispose to cardiac ischemia (especially in women).

Central Blood Pressure Under Angiotensin and Calcium Channel Blockade

Hemodynamic studies have shown that, in healthy subjects, there is a gradual widening of the height of the pressure waveform as it travels from the central (aortic) elastic arteries to the peripheral muscular arteries (brachial artery)1 (Figure). This disparity, which tends to disappear in the presence of vascular disease/aging, does not require any additional energy input within the arterial system, because the mean arterial pressure (MAP) and even the diastolic blood pressure (BP) remain almost unchanged between the 2 arterial sites. This finding is mainly attributed to the gradual increase (ie, amplification) of systolic BP (SBP) or pulse pressure (PP) along the arterial tree and is conventionally quantified as the ratio of the SBP or PP between the 2 sites (eg, SBP arm:SBP aorta)1 (Figure). Figure. Schematic personal representation of the forward and reflected pressure waves in the aorta and the influence of their timing on local PP. The definition of SBP amplification is indicated. In the present issue of Hypertension , Matsui et al2 have shown the superiority of calcium channel blockers (CCBs) over diuretics using the following protocol: the angiotensin receptor blocker olmesartan was combined with the CCB azelnidipine and compared with the same olmesartan associated with the diuretic hydrochlorothiazide. Central SBP was reduced to a greater degree with the CCB than with the hydrochlorothiazide. This resulted in an increase of SBP and PP amplification with the CCB, despite the lack of a significant difference in the brachial SBP reduction between the 2 …

Increased pulse pressure is associated with long left ventricular ejection duration in isolated systolic hypertensives

Increased pulse pressure is associated with long left ventricular ejection duration in isolated systolic hypertensives

Assay of digitalis glycosides in man

The administration of digitalis glycosides is followed by a consistent and dose-dependent abbreviation of the duration of left ventricular ejection in normal individuals. The changes in left ventricular ejection time determined from the indirect carotid arterial tracing and corrected for heart rate (ejection time index) offer an easily derived measure of the myocardial response to digitalis. In the present studies, this effect of the cardiac glycosides was employed in comparing the temporal course of the action of four digitalis glycosides in man. Deslanoside (1.6 mg.) and ouabain (1.0 mg.) intravenously induced a temporally equivalent onset of action which reached a maximum 20 minutes after administration. Onset of the effect of digoxin (1.6 mg. intravenously) was similarly rapid. The initial response to digoxin was followed by a secondary delayed effect which reached its maximum six hours after drug administration. Digitoxin (1.6 mg. intravenously) evoked a slight initial effect followed by a slowly developing, late response which reached a maximum six hours after its administration. A logarithmic temporal dissipation of the effects of the digitalis glycosides on the ejection time index occurred. From the dissipation curves the physiologic half-lives of the glycosides were calculated: ouabain, 22 hour; digoxin, 33 hour; deslanoside, 36 hour; and digitoxin, 102 to 112 hour. When administered orally, digoxin elicited a response characterized by a late onset, delayed maximum and diminished potency when compared to the intravenously administered agent. The effects of digitoxin on the ejection time index were virtually identical by the intravenous and oral routes. The action of digitalis glycosides on ejection time index was demonstrated in patients with heart failure and in individuals with complete heart block. These effects on ejection time index offer a new, objective and quantitative approach to the measurement of the cardiac response to digitalis in man.

THE EFFECT OF DIGITALIS ON VENTRICULAR EJECTION IN NORMAL HUMAN SUBJECTS.

The administration of deslanoside to normal subjects was associated with an abbreviation in the duration of all phases of mechanical systole in the absence of a change in cardiac output. The decrease in the ejection time index following deslanoside is an expression of the [see figure in the PDF file] diminution in the duration of ventricular ejection relative to heart rate and reflects the enhanced mean rate of left ventricular ejection following the drug. These observations lend additional evidence for the positive inotropic effect of digitalis in the normal heart. Serial determinations of the left ventricular ejection time index following deslanoside afforded observations on the temporal course of the effect of the drug. The decrease in the left ventricular ejection time index proved to be dose dependent, lending evidence for a direct relationship between the positive inotropic effect and the decreased duration of left ventricular ejection.

New Observations on the Left Ventricular Contractile Response to Digitalis in Man.

Excerpt The administration of deslanoside to normal individuals is associated with a decrease in the duration of left ventricular ejection (LVET). This effect of the drug, which occurs in the absen...

DETERMINANTS OF DURATION OF LEFT VENTRICULAR EJECTION IN NORMAL YOUNG MEN.

The factors governing the duration of ejection were studied by statistical techniques at rest and during exercise in man. Data consist of 207 points in 20 subjects. Linear stepwise regression analysis results in the following formula for the prediction of the duration of ejection from the heart rate, stroke index, and the aortic diastolic pressure: duration of ejection = .36646 - .00108 (rate) - .00036 (diastolic pressure) + .00076 (stroke index). The correlation coefficient is 0.90 on comparison with the measured duration of ejection. The error of estimate is .0155 sec. The validity of the three variables was confirmed by factor analysis. Heart rate was found to be the major determinant of the duration of ejection. Stroke index and pressure have a relatively minor but statistically significant effect. ventricular ejection time prediction and calculation; factor analysis of ventricular ejection; cardiac output during exercise; heart rate, stroke index, and ventricular ejection; aortic diastolic pressure and ventricular ejection Submitted on July 18, 1963

LEFT VENTRICULAR EJECTION TIME INDEX IN MAN.

The present studies were undertaken in an attempt to formulate an accurate expression of the relationship between the duration of left ventricular ejection and heart rate in man. On the basis of regression equations relating the duration of left ventricular ejection and heart rate in normal individuals, the index LVET + .0016 HR was derived and tested in normal adults and prepubertal children. The left ventricular ejection time index (ETI) remained constant and reproducible over the range of heart rate from 50 to 150 and yielded more consistent values in this range of heart rate than did previously derived equations. A slight but significantly higher value of the ETI was present in the adult females when compared to the adult males, while no significant difference according to sex was apparent in the children. A decrease in ETI was found when cardiac output was diminished in normal individuals during 60° head-up tilt and in patients with congestive heart failure. Of note was the finding of a significant correlation between the level of the ETI and the cardiac output in these situations. Submitted on December 13, 1962