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At least 91 records · Page 5Linked to original sources
PubMed1979

Effect of therapeutic-dose irradiation on left ventricular function in conscious dogs.

Every week, 8 conscious, chronically instrumented dogs underwent left ventricular (LV) function studies before, during, and after cardiac irradiation with cobalt 60 (myocardial dose of 5,000 rads at 200 rads per day through a 5 X 5 cm port). During the weekly LV function studies, left atrial pressures were raised by rapid infusion of balanced saline solution. Heart rate, aortic pressures, left and right atrial pressures, LV pressure, left ventricular end-diastolic pressure (LVEDP), and maximum rate of rise of LV pressure were recorded. Electrocardiograms were made. Cardiac outputs were obtained by thermodilution. Stroke volume, LV stroke work, and LV minute work were calculated. LV function curves were constructed each week. All dogs lost weight and became irritable after approximately 800 rads. The electrocardiograms showed signs of myocardial injury after 1,200 rads. All variables were slightly depressed during the first 8 weeks following irradiation. At the eleventh week, both left atrial pressure and LVEDP increased significantly and LV function declined. There was also clinical evidence of LV failure at rest and after volume loading. This study documents that external cardiac irradiation, in a therapeutic dose and schedule range, causes depression of LV function. These functional changes were partially reversed when the follow-up study was continued to six months after irradiation.

Animals↗
PubMed1987

[Functional status of the left side of the heart in patients with ischemic heart disease during isometric exercise].

Hemodynamic parameters of left-ventricular and left-atrial contractility and pumping function were examined in 47 males with postinfarction cardiosclerosis and no clinical signs of circulatory insufficiency and in 30 normal male subjects, exposed to isometric leg exercise with the highest possible compression force. At the height of exercise, normal subjects showed increased left-ventricular myocardial contractility along with the initiation of the Frank-Starling mechanism, spreading to the left atrium as well, while coronary patients responded to increased stress by growing left-atrial reservoir function during the first minutes of exercise, and activated left-atrial transport and pumping functions afterwards. Isometric leg exercise is capable of detecting left-atrial and left-ventricular pumping and contractility disorders in coronary patients.

Adult↗
PubMed1992

Influence of loading conditions and contractile state on pulmonary venous flow. Validation of Doppler velocimetry.

BACKGROUND: Although recent studies suggest that pulmonary venous flow velocities may be used to evaluate left ventricular diastolic function, the influence of loading conditions and contractile state on the magnitude and pattern of pulmonary venous flow are poorly understood. METHODS AND RESULTS: Fourteen anesthetized open-chest mongrel dogs were instrumented with pulmonary venous flow probes, atrial sonomicrometer crystal paris, and high-fidelity micromanometers; transesophageal Doppler echocardiography was used to obtain simultaneous pulmonary venous flow velocities. Measurements were made over a wide range of left atrial pressure obtained by either intravascular volume infusion and inferior vena caval balloon inflation (n = 8), halothane inhalation (n = 6), or phenylephrine infusion (n = 5). There was an excellent correlation for pulmonary venous systolic (J) to diastolic (K) time integral between the Doppler and flow probe signal (r = 0.94; SEE, 0.18). When left atrial pressure was increased by volume infusion, there was a significant linear relation between mean left atrial pressure and the Doppler J/K peak (r = 0.64; SEE, 3.4 mm Hg) and flow velocity-time integral ratio (r = 0.75; SEE, 2.9 mm Hg). By contrast, when left atrial pressure was elevated by halothane-induced cardiac depression, there was no correlation. The independent determinants of the pattern of pulmonary venous flow (stepwise multiple linear regression analysis) under all conditions were atrial systolic shortening, aortic systolic pressure, heart rate, and left ventricular end-systolic dimension (cumulative r = 0.80). CONCLUSIONS: The pattern of pulmonary venous flow can be measured accurately with Doppler velocities and is differentially influenced by loading conditions and myocardial contractile state; in the absence of myocardial contractile dysfunction, the pattern of pulmonary venous flow may provide an estimate of left atrial pressure; and pulmonary venous flow is determined largely by atrial systolic function.

Animals↗
PubMed1978

Echocardiographic evaluation of left ventricular filling in mitral stenosis. Role of atrial contraction.

Echocardiographic evaluation of left ventricular volume change during rapid and atrial filling periods was made in patients with mital stenosis. The significant reduction of rapid filling volume was observed and the rate of rapid filling was approximately the half of normal in mitral stenosis. The rapid filling period showed a good correlation to the mitral valve area measured at operation. After surgical treatment, the rate of rapid filling was significantly increased but was still significantly smaller than normal. It was suggested that the remained structural abnormality of mitral apparatus depressed the inflow through the mitral valve in early diastole despite successful mitral valvotomy. Left ventricular filling during atrial contraction (atrial filling) was augmented twice as much as normal in patients with milder mitral stenosis, compensating the decreased early diastolic filling. In contrast, the atrial filling did not increase in severe mitral stenosis, resulting in the decreased cardiac output. Following mitral commissurotomy, the atrial filling in milder mitral stenosis was reduced but remained significantly larger than normal. There was no change of atrial filling in severe mitral stenosis postoperatively. This fact suggested the existence of impaired contraction of left atrium in cases with severe mitral stenosis. Our results show that the altered left atrial transport function plays an important role in the left ventricular filling in mitral stenosis.

Adult↗
PubMed1992

[A case of tricuspid pouch associated with ventricular septal defect and functional left ventricular-right atrial communication].

We reported a 60-year-old woman with tricuspid pouch associated with ventricular septal defect and subsequent left ventricular-right atrial communication. Preoperative angiographic findings suggested the presence of membranous septal aneurysm, ventricular and atrial septal defects, and tricuspid insufficiency. However, at operation, besides perimembranous inlet type ventricular septal defect, a pouch, 1.5 cm in diameter was found in the adjacent part to the septal leaflet within the anterior one of the tricuspid valve. The ventricular septal defect was closed with a patch. From these findings, it is speculated that the tricuspid pouch was formed by the effect of jet stream through the ventricular septal defect.

Diagnosis, Differential↗
PubMedDate not supplied

Effect of pericardium on left ventricular early filling assessed by pulsed Doppler echocardiography.

Pericardial effect on left ventricular early filling was studied in six dogs by use of pulsed Doppler echocardiography. Rapid dextran infusion was used to manipulate left atrial pressure. Left ventricular peak early filling velocities before and after pericardiectomy were measured at different levels of left atrial pressure with right atrial and left ventricular pressures. Peak early filling velocity correlated with mean left atrial pressure before and after pericardiectomy. Before pericardiectomy, when mean right atrial pressure exceeded 12 mm Hg, further increase of the velocity was not observed in spite of volume loading. After pericardiectomy, peak early filling velocity became higher and the slope of the relation line between mean left atrial pressure and the velocity became steeper than before pericardiectomy. When the filling pressure was denoted by the transmural mean left atrial pressure, the points on the relation line before pericardiectomy fell along the relation line after pericardiectomy. We conclude the pericardium exerts an external constraint on left ventricular early filling. Therefore we should not consider the absolute but the transmural filling pressure when estimating left ventricular early diastolic function with use of Doppler-derived left ventricular early filling velocity.

Animals↗
PubMed1992

High levels of plasma atrial natriuretic factor and impaired left ventricular diastolic function in hypertensives without left ventricular hypertrophy.

OBJECTIVE: To seek possible correlations between plasma atrial natriuretic factor (ANF) and left ventricular diastolic function (LVDF) in hypertensive patients. DESIGN: Since LVDF abnormalities can be detected in patients with normal left ventricular mass, we studied a group of hypertensive patients without left ventricular hypertrophy. METHODS: Untreated hypertensive patients (n = 23) and normotensive control subjects (n = 19) were studied. LVDF indices were obtained by M-mode and pulsed Doppler echocardiography. Blood samples for plasma ANF were taken in the recumbent position from subjects on normal-sodium intake. RESULTS: Plasma ANF levels were significantly higher in hypertensive patients than in normotensive subjects. All indices for systolic function were normal in both normotensive subjects and hypertensive patients. Left atrial diameter was significantly higher for hypertensive patients than for normotensive subjects. Considering LVDF, all indices for ventricular filling were found to be altered, on average, in hypertensive patients, the only exception being peak early velocity. In addition, significant correlations were found between plasma ANF and the pulsed Doppler parameters of left ventricular filling, peak atrial velocity and the peak early:peak atrial velocity ratio. Overall correlations between plasma ANF and left atrial diameter, and between left atrial diameter and left ventricular mass index were also observed. CONCLUSIONS: The high levels of plasma ANF observed in our hypertensive patients and their correlation with the LVDF indices (which mainly reflect the atrial contribution to ventricular filling) could be the result of an increased atrial stretch due to diastolic ventricular dysfunction. This may exist in hypertensive patients before the development of ventricular hypertrophy.

Adult↗
PubMed1991

Nonphysiological left heart AV intervals as a result of DDD and AAI "physiological" pacing.

DDD and AAI pacemakers are considered physiological, since they preserve atrioventricular (AV) synchrony. Artificial pacing, however, is performed largely from right heart chambers, causing aberrant depolarization pathways. Pacing at the right atrial appendage (RAP) is known to delay left atrial contraction due to interatrial conduction time (IACT), and right ventricular (RV) apical pacing (RVP) delays left ventricular (LV) contraction due to interventricular conduction time (IVCT). These delays may render the left heart AV intervals (LAV) either too short or too long, thus affecting LV systolic function. The purpose of this study was to evaluate the actual LAV intervals during conventional, right heart AAI and DDD pacing. Resulting LAV intervals were compared to programmed AV values during all DDD pacing modalities. Ten patients with DDD and six patients with AAI pacemakers were studied. IACT was measured from the atrial spike to the onset of left P wave, as recorded by an esophageal lead. Systolic time intervals were measured using either a carotid pulse tracing or a densitogram (photoplethysmography). LV function was appraised by measuring rate-corrected LV ejection time (LVETc). IVCT was measured indirectly as the lengthening of LV preejection period (PEP) caused by RV pacing, as compared to normal depolarization pathway. Intrinsic IACT and IVCT were considered zero. Right heart AV intervals (RAV) were measured from surface ECG and LAVs were calculated according to the following equations: Sinus Rhythm: LAV = RAV; Atrial Pace + Ventricular Sense: LAV = RAV - IACT; Atrial Sense + Ventricular Pace: LAV = RAV + IVCT; Sequential AV Pace: LAV = RAV - IACT + IVCT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effects of changes in heart rate and atrial filling pressure on the performance characteristics of isolated perfused pumping rat hearts.

Biomechanical indices of left ventricular performance were measured and computed by an on-line minicomputer in 13 isolated perfused working rat hearts subjected to a regimen of left atrial filling pressures and heart rates, to determine perfusion conditions for optimum heart work. We found that maximum values of most of the indices are achieved at a left atrial filling pressure of 20 to 25 cm H2O and a heart rate of 330 to 360 beats/min. Most of the performance indices when considered as functions of left atrial filling pressure display Starling-type behaviour: they rise with increasing left atrial pressure, reach a maximum at 20 to 25 cm H2O, and decline with further increases in left atrial pressure. Values for left ventricular (dP/dt)max, between 6000 to 8000 mm Hg s-1, and -(dP/dt)min, between 4000 to 6000 mm Hg s-1, are considerably higher than values previously reported. We believe this to be due to improved sampling techniques.

Animals↗
PubMed1987

Left ventricular function in adults with atrial septal defect.

Sixteen patients with secundum atrial defect were catheterized giving emphasis to the analysis of the left ventricle at end systole and mid-ejection. The mean ejection fraction of the group was subnormal 57 + 8% when compared with 30 normal patients (71 + 109) P less than .005. Eight patients showed elevated end-diastolic volumes (156 + 10cc) when compared to our normal group (95% + 10cc) P less than .005. A total of 32 hypokinetic and 35 tardokinetic areas were found. Eight patients were restudied after nitroglycerin (0.4 mg sublingually) with an improvement in the ejection fraction from 54% to 70% (P less than .005) and normalization of most of the hypokinetic areas. No correlation was found between total ejection fraction or total systolic wall motion and the shunt size. Probably these left ventricular wall motion abnormalities are primary and not due to the shunt size.

Adolescent↗
PubMed1989

Comparison of Doppler indexes of left ventricular diastolic function with simultaneous high fidelity left atrial and ventricular pressures in idiopathic dilated cardiomyopathy.

Doppler echocardiographic indexes of ventricular inflow have been used clinically to characterize left ventricular (LV) diastolic function. The reliability of these indexes as markers for intrinsic myocardial diastolic properties has been questioned. Micro-manometer left atrial (LA) and LV pressures as well as transmitral Doppler flow velocity signals and M-mode and 2-dimensional echocardiograms were simultaneously recorded. These unique measurements were acquired in patients with dilated cardiomyopathy under baseline conditions and during infusion of high dose amrinone. The response to amrinone was chosen as a hemodynamic model because this drug has previously been described as having beneficial effects on overall LV systolic and diastolic performance. At peak amrinone effect, LV contractility increased (as assessed using load independent end-systolic indexes) and early diastolic relaxation improved whereas passive chamber stiffness, heart rate and stroke volume were unchanged. There was a significant decrease in LV end-diastolic pressure as well as a parallel downward shift of the entire LV diastolic pressure-dimension relation. These findings, which indicated an improvement in overall LV diastolic properties, probably represent the combination of more rapid early diastolic relaxation in conjunction with a reduction in venous return, the relief of pericardial restraint or the reduction in right ventricular-LV interaction. In contrast, the ratios of Doppler-determined peak transmitral early-to-late flow velocities and early-to-late diastolic flow velocity integrals decreased with amrinone infusion, thereby suggesting a drug-induced decrease in LV diastolic compliance. Thus, in patients with idiopathic dilated cardiomyopathy, administration of amrinone has a complex effect on LV diastolic properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Factors determining maintenance of sinus rhythm after chronic atrial fibrillation with left atrial dilatation.

Successful therapy of atrial fibrillation (AF) has been reportedly influenced by a variety of factors including patient age, type of underlying heart disease, duration of arrhythmia, left ventricular function and left atrial (LA) size. To determine which of these factors are associated with maintenance of sinus rhythm after conversion, 43 patients with symptomatic chronic AF in the setting of a dilated left atrium (greater than or equal to 45 mm, range 45 to 78) were followed for at least 6 months after the return of sinus rhythm. Class IA drugs, IC drugs or amiodarone were used for therapy. Life table analysis showed sinus rhythm to be maintained in 81% for 6 months, 79% for 12 months and 60% for 24 months. Factors positively associated with success were conversion with drug therapy alone, duration of chronic AF less than or equal to 1 year, absence of mitral valve disease and LA dimension less than or equal to 60 mm (all p less than 0.05). Patient age, left ventricular function and presence of coronary disease were not associated with outcome. Thus, patients with moderate LA dilatation (45 to 60 mm) and a short duration of chronic AF can often be maintained in sinus rhythm, especially if they convert with pharmacologic intervention alone.

Aged↗
PubMed1991

Hemodynamic response to intracoronary infusion of atrial natriuretic factor in patients with normal or altered left ventricular function.

To assess the effects of atrial natriuretic factor (ANF) on cardiac function, synthetic human ANF was infused directly into the left main coronary artery of eight patients with congestive heart failure (CHF) and six subjects with normal left ventricular (LV) function (controls) who underwent cardiac catheterization. ANF infusion at the incremental rates of 60, 125, 400, and 800 ng/min induced a dose-related increase in plasma ANF concentrations in the coronary sinus, from 1,223 +/- 590 to 3,923 +/- 1,123 pg/ml in patients with CHF (p less than 0.01) and from 1,041 +/- 605 to 2,710 +/- 1,741 pg/ml in controls (p less than 0.01). Peripheral plasma ANF concentrations (femoral artery) increased from 538 +/- 278 to 752 +/- 262 pg/ml (p less than 0.01) in patients with CHF and from 193 +/- 63 to 401 +/- 147 pg/ml (p less than 0.01) in controls. The increase in peripheral or coronary sinus plasma ANF concentrations did not differ between patients with CHF and controls. At the three lowest ANF infusion rates, cardiac index (CI), systemic vascular resistance (SVR), and LV contractility assessed by peak positive dP/dt remained unchanged both in patients with CHF and in controls. At the highest ANF infusion rate, CI increased from 2.18 +/- 0.53 to 2.54 +/- 0.49 L/min/m2 (p less than 0.01) and SVR decreased from 14.6 +/- 3.6 to 12.8 +/- 4.5 mm Hg.min/L (p less than 0.01) in patients with CHF. There was no associated change in heart rate (HR), mean arterial blood pressure (MAP), cardiac filling pressures, or peak positive dP/dt.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗