Pre-ejection Period To Left Ventricular Ejection Time Research Articles

Computer-Aided Detection of Fiducial Points in Seismocardiography through Dynamic Time Warping.

Accelerometer-based devices have been employed in seismocardiography fiducial point detection with the aid of quasi-synchronous alignment between echocardiography images and seismocardiogram signals. However, signal misalignments have been observed, due to the heartbeat cycle length variation. This paper not only analyzes the misalignments and detection errors but also proposes to mitigate the issues by introducing reference signals and adynamic time warping (DTW) algorithm. Two diagnostic parameters, the ratio of pre-ejection period to left ventricular ejection time (PEP/LVET) and the Tei index, were examined with two statistical verification approaches: (1) the coefficient of determination (R2) of the parameters versus the left ventricular ejection fraction (LVEF) assessments, and (2) the receiver operating characteristic (ROC) classification to distinguish the heart failure patients with reduced ejection fraction (HFrEF). Favorable R2 values were obtained, R2 = 0.768 for PEP/LVET versus LVEF and R2 = 0.86 for Tei index versus LVEF. The areas under the ROC curve indicate the parameters that are good predictors to identify HFrEF patients, with an accuracy of more than 92%. The proof-of-concept experiments exhibited the effectiveness of the DTW-based quasi-synchronous alignment in seismocardiography fiducial point detection. The proposed approach may enable the standardization of the fiducial point detection and the signal template generation. Meanwhile, the program-generated annotation data may serve as the labeled training set for the supervised machine learning.

Diagnosis and Treatment of Low Systemic Blood Flow in Preterm Infants

After completing this article, readers should be able to: 1. Delineate the short- and long-term adverse outcomes associated with low systemic blood flow. 2. Explain why it is not appropriate to use blood pressure and population criteria for hypotension to determine which infants who have low systemic blood flow need cardiovascular support. 3. Describe the various hemodynamic states in neonates and the assessment that is useful in allowing discrimination between these states. 4. Characterize the hemodynamic effects of dopamine and dobutamine in neonates. 5. Delineate the most common characteristics of infants who fail to maintain superior vena cava flows despite the use of inotropes. Low systemic blood flow (SBF) commonly occurs in preterm infants who have respiratory distress in the first postnatal day. Such low flows are strongly associated with neonatal morbidity, including peri/intraventricular hemorrhage (P/IVH), developmental impairments, and mortality. Diagnosing which infants have low SBF is problematic; use of blood pressure (BP) and signs of poor tissue perfusion, including capillary refill times (CRT), poor renal function, and acidosis, results in substantial delays in the initiation of cardiovascular support and a proportion of affected infants missing treatment. The traditional approach to cardiovascular support of the preterm infant has been to identify infants who have hypotension and to use agents, particularly dopamine, titrated to improve BP. However, this strategy may not be the best for improving SBF, and it is yet to be demonstrated that this approach improves neonatal outcomes. This review focuses on identifying which infants have low SBF or organ blood flow, discusses mechanisms for low flows, and examines potential therapies for treating or preventing low flow. Cardiovascular compromise occurs in a number of clinical scenarios in preterm infants, but it is most common on the first postnatal day. Not all infants who have low SBF will be suspected based on clinical signs, including …

Enhancement of parasympathetic cardiac activity during activation of muscle metaboreflex in humans.

We measured the changes in heart rate (HR) variability estimated from the standard deviation of the R-R intervals to evaluate cardiac parasympathetic tone noninvasively before and during activation of muscle metaboreflex induced by postexercise muscle ischemia. Eight healthy male subjects performed sustained handgrip at 50% maximal voluntary contraction followed by forearm occlusion. Mean arterial pressure, cardiac stroke volume, and ratio of cardiac preejection period to left ventricular ejection time (PEP/LVET) were also measured. During the 2-min occlusion after 60 s of handgrip with voluntary respiration, HR variability and mean arterial pressure were significantly increased from baseline (54.4 +/- 6.1 to 80.1 +/- 12.8 ms and 81 +/- 1 to 99 +/- 3 mmHg, respectively) and PEP/LVET was decreased from resting level of 0.404 +/- 0.022 to 0.363 +/- 0.036. During occlusion and recovery, HR did not change from baseline level in any experiment. There was no influence of occlusion itself or of cessation of exercise per se on any parameters. Although overall enhanced HR variability was seen, probably due to lower breathing frequency and larger tidal volume, similar results were also obtained from an experiment with controlled respiration, showing that the increase in HR variability was not due to the changes in tidal volume or breathing frequency during occlusion. In conclusion, the HR variability is increased during activation of the muscle metaboreflex induced by postexercise muscle ischemia in humans. This finding shows that the parasympathetic cardiac tone is enhanced during activation of the muscle metaboreflex in humans and balances enhanced cardiac sympathetic activity to result in an unchanged HR.(ABSTRACT TRUNCATED AT 250 WORDS)

運動中の体温調節反応と心周期分画の変動との関係

This study was conducted to clarify the relationship between skin blood flow and sweating during exercise, and also to determine the relationship between those thermoregulatory responses and changes in cardiac time intervals during exercise. Six healthy males performed bicycle exercise at 40% V^^.O_2 max for 40-min at an ambient temperature of 28℃ (50% RH).Physiological parameters including esophageal temperature (Tes), forearm sweating rate (m_<sw>),forearm skin blood flow (LDF) and cardiac time intervals were measured. 1) Tes threshold for initiation of cutaneous vasodilation was higher than that of sweating in each subject. 2) m_<sw> increased with Tes, while the increase of LDF leveled off at 38.1℃ as a breaking Point (bp). 3) When Tes was between 37.6-38.1℃ , total electromechanical systole (QS_2) shortened continuously, but diastolic time (DT) remained constant. When Tes was higher than 38.1℃, the rate of shortening of DT was larger than that of QS_2. The pattern of change of left ventricular ejection time (LVET) was similar to that of QS_2. 4) The trough was formed in the ratio of QS_2 to DT (QS_2/DT) at the bp. When Tes was higher than the bp, the rates of increase were slightly less in the ratio of pre-ejection period to LVET (PEP/LVET) and the ratio of electrical systole to QS_2 (QT/QS_2). From these findings, the following conclusions were obtained: Tes threshold of skin blood flow is higher than that of sweating. A bp is formed for skin blood flow but not sweating during exercise in a warm environment. It is suggested that there is a interrelationship between the control of skin blood flow and the change of cardiac function because the specific changes of cardiac interval time are at the bp of LDF.

Disparate difference in preload reserve between myocardial hypertrophy due to essential hypertension and hypertrophic cardiomyopathy.

To investigate the left ventricular preload reserve in essential hypertensives, the legs-up procedure was performed and the data were compared with those in patients with non-obstructive hypertrophic cardiomyopathy and in normal subjects. Stroke volume index and the following systolic time intervals were measured before and after the legs-up procedure: left ventricular ejection time, pre-ejection period and the ratio of pre-ejection period to left ventricular ejection time (PEP/ET). No changes in blood pressure, heart rate or plasma catecholamine levels were noted before and after the legs-up procedure in all groups. A shortening in the pre-ejection period, a prolongation of ejection time, a decrease in the PEP/ET ratio and an increase in the stroke volume index were observed in essential hypertensives and in normal subjects. However, the changes in these parameters were not observed in patient with hypertrophic cardiomyopathy. The legs-up procedure is known to increase left ventricular end-diastolic volume. These results suggest that myocardial hypertrophy due to essential hypertension preserves the same preload reserve as in normals, but hypertrophic cardiomyopathy does not.

Combining left ventricular systolic time intervals and M-mode echocardiography in the evaluation of primary pulmonary hypertension in women.

Eight patients with primary pulmonary hypertension underwent systolic time intervals, M-mode echocardiography, and direct hemodynamic studies in order to determine the correlation between noninvasive parameters and hemodynamic variables and to evaluate the utility of these noninvasive studies in primary pulmonary hypertension. The ratio of the pre-ejection period to left ventricular ejection time (PEP/LVET) of the systolic time intervals was abnormally increased (greater than 0.42) for each subject; the increase in the PEP/LVET was secondary to a shortening of the left ventricular ejection time in four patients, prolongation of the pre-ejection period in one, or a combination of such, noted in three patients. In contrast, echocardiographic parameters of left ventricular function, specifically percent change in the minor axis of the left ventricle with systole, velocity of circumferential fiber shortening, and ejection fraction, were normal. In addition, a very good correlation was noted between PEP/LVET and total pulmonary resistance (r value = -0.89, p less than 0.05), while the echocardiographic parameters correlated well with stroke volume and cardiac output (r values ranged from 0.68 to 0.72, p less than 0.05). These results indicate that in primary pulmonary hypertension, the performance of both systolic time intervals and M-mode echocardiography noninvasively provides useful information concerning the hemodynamic status of these patients. Systolic time intervals provide an estimation of overall cardiac-cardiovascular performance, rather than left ventricular function alone, which in turn, is validly examined by M-mode echocardiography.

Left ventricular function in patients with diabetes mellitus.

The left ventricular function was assessed in 70 diabetics under 60 years of age without clinically evident heart disease using established non-invasive methods, these include systolic time interval method and echocardiography. The ratio of pre-ejection period to left ventricular ejection time (PEP/ET) was remarkably elevated in diabetics with severe microangiopathy (0.431 +/- 0.037). Even in diabetics without microangiopathy PEP/ET ratio was significantly higher (0.374 +/- 0.037) compared with that in controls (0.331 +/- 0.023, P less than 0.01). Most of diabetics with a PEP/ET value of higher than 0.40 were not under proper care with regard to diabetic control. A tendency toward normalization of PEP/ET values was often observed with the improvement in diabetic control during six to twelve months among the inadequately controlled diabetics. Isovolumic relaxation time in diabetics was longer than in controls (80 +/- 14 msec, 59 +/- 11 msec, P less than 0.005). Our results suggest that abnormalities of left ventricular function in diabetics may be related to not only severity of microangiopathy but also the state of diabetic control. The maintenance of adequate control of diabetes seems to play an important role in the prevention of congestive heart failure in patients with diabetes mellitus.

Combined systolic time intervals and M-mode echocardiography in the evaluation of central hemodynamics in primary pulmonary hypertension.

8 patients with moderate to severe primary pulmonary hypertension underwent systolic time intervals, M-mode echocardiography, and direct hemodynamic studies in order to determine the correlation between noninvasive parameters and hemodynamic variables and to evaluate the utility of these noninvasive studies in primary pulmonary hypertension. The ratio of the pre-ejection period to left ventricular ejection time (PEP/LVET) of the systolic time intervals was abnormally increased (greater than 0.42) for each subject; the increase in the PEP/LVET was secondary to a shortening of the left ventricular ejection time in 4 patients, prolongation of the pre-ejection period in 1, or a combination of such, noted in 3. In contrast, echocardiographic parameters of left ventricular function, specifically, percent change in the minor axis of the left ventricle with systole, velocity of circumferential fiber shortening, and ejection fraction, were normal. In addition, a very good correlation was noted between PEP/LVET and total pulmonary resistance (r value = -0.89), while the echocardiographic parameters correlated well with stroke volume and cardiac indices (r values ranged from 0.68 to 0.72). These results indicate that in primary pulmonary hypertension, systolic time intervals provide an estimation of overall cardiac-cardiovascular performance, rather than left ventricular function alone, which in turn, is validly examined by M-mode echocardiography.

Mechanism of reduced cardiac stroke volume at high altitude.

Two postulates have been advanced to account for reduced stroke at high altitude: (1) diminished venous return secondary to contracted plasma volume and (2) left ventricular (LV) dysfunction secondary to hypoxia. To test these hypotheses, we assessed LV dimensions and contractility indices by M-mode echocardiography and systolic time intervals in 11 young men at sealevel and serially for 10 days at 3100 m altitude. Mean LV end-diastolic dimension fell 16% after 6-8 days, with a 20% decrease in plasma volume reflected by hematocrit rise. Pre-ejection period to LV ejection time (PEP/LVET) ratio was increased after 1-2 days. All indices of contractility were unchanged at rest, and slightly enhanced during exercise. Thus stroke volume falls and PEP/LVET ratio rises at 3100 m because of diminished venous return despite preservation of LV systolic performance.

Systolic time intervals in chronic severe anaemia and effect of diuretic and digitalis.

Systolic time intervals were measured from simultaneous high speed recordings of the electrocardiogram, phonocardiogram, and carotid artery pulse in 15 men with chronic severe anaemia not in heart failure and with a normal heart size, and in 15 normal men. Heart rates, electromechanical systole (QS2), pre-ejection period index (PEPI), left ventricular ejection time index (LVETI), and the ratio of pre-ejection period to left ventricular ejection time (PEP/LVET) did not differ significantly in the two groups. After the intravenous administration of frusemide in 10 of the anaemic patients, the pre-ejection period index was prolonged, the PEP/LVET ratio increased, heart rate increased, and the left ventricular ejection time index shortened. Intravenous digoxin did not alter the QS2 interval and heart rate significantly in the anaemic subjects. Left ventricular function in chronic severe anaemia as measured by systolic time intervals does not differ from that of normal controls. The effect of frusemide on the systolic time intervals is explained as an effect of the fall in preload, bringing cardiac function further down on the ascending limb of the Frank-Starling curve. Other related studies are discussed.

Pindolol in the treatment of hypertension: Systolic time intervals as a predictor of response to beta receptor blockade

Seventy-two hypertensive patients were treated with pindolol, a beta adrenergic blocking drug with intrinsic sympathomimetic activity. Serial measurements of systolic time intervals were utilized (1) to determine whether the therapeutic response to pindolol was predictable from pretreatment measurements, and (2) to assess changes in cardiac function during a 15 week treatment period. Patients with an abnormal pretreatment ratio of preejection period to left ventricular ejection time (PEP/LVET) of greater than 0.42 were less likely to respond with a decrease in mean blood pressure of greater than 10 percent (8 of 22) than were patients with a normal (0.42 or less) pretreatment PEP/LVET ratio (33 of 50) (p

Cardiovascular Manifestations in Systemic Lupus Erythematosus : SYMPOSIUM ON SECONDARY MYOCARDIAL DISEASE : 44th Scientific Session of the Japanise Circulation Society

Cardiovascular manifestations in 48 patients with systemic lupus erythematosus were investigated by means of echocardiography and other non-invasive cardiac function tests. During the mean follow-up period of 17 months, 94 per cent of the patients showed abnormalities in the cardiac function tests. Pericardial effusion, a most frequent abnormality, was noted in 53 per cent of the patients at the active phese and in 12 per cent at the inactive phase. In the normotensive patients, echocardiographic values and ratio of pre-ejection period to left ventricular ejection time (PEP/LVET) changed toward normal range with change from the active phase to the inactive, and remained unchanged after a long-term corticosteroid therapy. In the hypertensives, on the other hand, these values changed toward more abnormal range after a long-term corticosteroid therapy. It was suggested that hypertension accerelates the cardiac lesions initiated by the autoimmune process. The patients who had manifested pericardial effusion showed more marked cardiac abnormalities than those without effusion at the both active and inactive phases, suggesting that some cardiac muscle involvement (lupus carditis) underlied behind the pericarditis. The patients who manifested Raynaud's phenomenon showed the significantly greater right ventricular dimension at the active phase than in those without this sign. As a mechanism for this result, the association of Raynaud's phenomenon and pulmonary vascular involvement was considered. Hence, the present study suggests 3 major mechanisms for the cardiac abnormalities in SLE: 1) lupus carditis, 2) pulmonary vascular involvement, and 3) systemic hypertension. The effects of corticosteroid therapy on these factors were discussed. A comparison between SLE and other allied diseases due to the auto-immune mechanism revealed that overlap syndrome is characterized by high incidence of increased right ventricular dimension and pulmonary hypertension.

Echocardiographic estimation of pulmonary artery pressure in transposition of the great arteries.

To determine their usefulness in estimating pulmonary artery pressure, left ventricular systolic time intervals (STI) were determined by echocardiography in 65 patients with dextro-transposition of the great arteries (TGA). The STI were measured from recordings of pulmonary valve motion at 100 mm/sec paper speed. The pre-ejection period (PEP) and the ratio of PEP to left ventricular ejection time (PEP/LVET) were directly related to pulmonary artery pressure. The strongest correlations were that between PEP/LVET and pulmonary artery diastolic pressure (r = 0.70) and that between PEP/LVET and the ratio of mean pulmonary pressure to mean systemic pressure (r = 0.71). A value of PEP/LVET of less than 0.26 was consistently associated with pulmonary artery diastolic pressures of less than 20 mm Hg and, in 28 of 31 patients, pulmonary artery pressure less than one-third of mean systemic arterial pressure. Pulmonary hypertension was present in 18 of 22 patients with PEP/LVET of 0.30 or greater; elevated PEP/LVET was also present in four patients with abnormalities of cardiac rhythm or conduction, two of whom also had angiographic evidence of myocardial dysfunction.

Guanabenz and methyldopa on hypertension and cardiac performance

In previous placebo-controlled studies, guanabenz was shown to be a safe and effective antihypertensive drug without acute effects on cardiac function. In view of its therapeutic advantages, a double-blind comparison of guanabenz with methyldopa was performed in a group of 36 patients over 6 mo. Both drugs produced statistically and clinically significant decreases in blood pressure with similar side effects. No laboratory or electrocardiographic abnormalities were found other than positive Coombs' tests which developed in 3 patients during methyldopa therapy. Cardiac performance in 26 of the patients, as measured by noninvasive techniques, showed no significant changes from either drug except for a progressive and statistically significant increase in systolic time interval (QS2) and the ratio of the pre-ejection period to left ventricular ejection time (PEP/LVET) during methyldopa therapy. For an additional 6 mo, continued efficacy and safety were shown under open conditions in those patients who had received guanabenz. The study suggests that guanabenz may be an important new antihypertensive drug because of effectiveness, absence of adverse cardiac effects, and paucity of side effects.

Negative Inotropic Effect of Lidocaine in Patients with Coronary Arterial Disease and Normal Subjects

The effect of administration of lidocaine on left ventricular performance was studied using systolic time intervals in nine normal subjects, eight patients with stable angina, and 15 patients with acute myocardial infarction. The greatest response in systolic time intervals occurred at three minutes after intravenous injection of lidocaine (100 mg), with values returning to baseline at 10 to 15 minutes. Administration of lidocaine produced a significant prolongation of the preejection period (PEP) corrected for heart rate in all groups and a prolongation of the ratio of PEP to left ventricular ejection time (PEP/LVET) in patients with angina. The group with acute myocardial infarction exhibited a hyperadrenergic state, as shown by a short baseline QS2I. The QS I was lengthened by administration of lidocaine in all groups, but this was more profound in those with acute myocardial infarction. These changes in systolic time intervals were still present at two hours after injection in six patients with acute myocardial infarction in whom an infusion of lidocaine followed the initial bolus. The effect of administering lidocaine after intravenous injection of propranolol (5 mg) was also studied in six normal subjects. Although propranolol therapy along prolonged the PEP/LVET, a further significant prolongation followed subsequent injection of lidocaine.

Cardiac performance three to eight weeks after acute myocardial infarction.

When cardiac performance was assessed three to eight weeks after uncomplicated acute myocardial infarction (AMI) in patients not in clinical cardiac failure, abnormalities of left ventricular (LV) function were demonstrated in 22 of 27 patients who, by clinical criteria, were recovering satisfactorily. Left ventricular end-diastolic pressure (LVEDP) was measured in 24 patients. It was elevated in 19, ranged from 14 to 20 mm Hg in 13, and was > 20 mm Hg in 6. Patients comprised three groups: group 1—5 patients with normal LVEDP, cardiac index (CI), stroke index (SI), and preejection period (PEP) to left ventricular ejection time (PEP/LVET) ratio; group 2—12 patients with elevated LVEDP (14 to 24 mm Hg) but normal CI, SI, and PEP/LVET ratio and; group 3—10 patients with elevated LVEDP (14 to 30 mm Hg), reduced CI and SI ( 0.381).