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Evaluation of right ventricular function during clinical left ventricular assistance.

Hemodynamic and mechanical parameters of right ventricular (RV) performance were measured in eight patients undergoing left ventricular (LV) assistance as a bridge to cardiac transplantation. All patients, even those with impaired RV performance, survived support and transplantation. The reduction of LV afterload produced by the left ventricular assist system (LVAS) results in RV afterload reduction, which permits even the marginal RV to function adequately during LVAS support.

Adult↗

Studies in clinical shock and hypotension: VI. Relationship between left and right ventricular function.

Left ventricular end diastolic (LVEDP) and mean right atrial (RAP) pressures were recorded simultaneously in 30 patients with shock (14 acute myocardial infarction, 10 acute pulmonary embolism or severe bronchopulmonary disease, and 6 sepsis). Myocardial infarction was characterized by a predominant increase in LVEDP, pulmonary disease by a predominant increase in RAP, and sepsis by a normal relationship between LVEDP and RAP. In all three groups a significant positive correlation was noted between RAP and LVEDP, with the regression line in cor pulmonale deviated significantly toward the RAP axis and the regression line in myocardial infarction exhibiting a zero RAP intercept at an elevated LVEDP.Low cardiac outputs with elevated LVEDP in myocardial infarction indicated severe left ventricular failure. Low outputs with elevated RAP in cor pulmonale were consistent with right ventricular overload. Although cardiac outputs often were normal in sepsis, low outputs with elevated cardiac filling pressures in some patients were consistent with a hemodynamic or humoral-induced generalized depression of cardiac performance.Vasoconstrictor and inotropic drugs often produced a functional disparity between the two ventricles, with the gradient between LVEDP and RAP increasing, apparently because of an increase in left ventricular work or an inadequacy of left ventricular oxygen delivery. Acute plasma volume expansion with dextran in patients with pulmonary vascular disease resulted in a somewhat more rapid rise in RAP than in LVEDP. In septic and myocardial infarction shock, however, LVEDP and RAP usually rose proportionally, with the absolute rise of LVEDP surpassing that of RAP. Although the absolute level of the central venous pressure thus may not be a reliable indicator of left ventricular function in shock, changes in venous pressure during acute plasma volume expansion should serve as a fairly safe guide to changes in LVEDP.

Journal Article↗

Combined thermodilution and two-dimensional echocardiographic evaluation of right ventricular function during respiratory support with PEEP.

In ten patients requiring respiratory support for an episode of acute respiratory failure (ARF), the best therapeutic level of PEEP was determined by measurement of changes in lung and chest wall compliance (CT) during a PEEP challenge from 0 to 20 cm H2O. During this challenge, hemodynamic monitoring combined with thermodilution measurement of right ventricular (RV) ejection fraction (EF) and two-dimensional echocardiographic measurement of RV size permitted assessment of the effects of increasing levels of PEEP on RV function. RV preload, as reflected by RV end-diastolic volume (EDV) and two-dimensional RV end-diastolic area (EDA), remained unchanged and RV diastolic compliance progressively decreased. On the other hand, RV systolic function, as assessed by RVEF and two-dimensional RV fractional area contraction (FAC), was progressively depressed. Substantial deleterious effects of PEEP were noted at high levels of PEEP including reduced CT and augmented pulmonary vascular resistance. Inadequate increase in RV preload to compensate for increased RV afterload resulted in depressed RV systolic function and contributed to the reduction in cardiac output. Finally, two-dimensional echocardiography proved to be more sensitive than fast-response thermodilution to evaluate change in RV function.

Echocardiography↗

Pressure segment length analysis of right ventricular function: influence of loading conditions.

The purpose of this study was to determine whether segment lengths measured from the right ventricular inflow and outflow tract regions of the right ventricle would accurately reflect true volume changes of the right ventricle and to determine the response of the right ventricle to afterload increases induced by both constricting the pulmonary artery (PAC) and embolizing the pulmonary circulation with glass beads (GBE). Three excised hearts were instrumented with segment-length crystals attached to the inflow and outflow tract regions, and saline was instilled into a balloon implanted inside the right ventricular cavity. The experiments showed a high correlation (r greater than or equal to 0.90 in all cases) between static segment lengths and volume instilled. In open chest, open pericardial canine experiments, vena caval occlusion reduced end-diastolic segments lengths and right ventricular systolic pressure consistent with a reduction in right ventricular end-diastolic volume. In a separate group of animals, volume loading with dextran increased inflow and outflow end-diastolic segment lengths and increased cardiac output. In two further groups of animals, one of which was pretreated intravenously with propranolol (Inderal), both forms of pressure overload increased end-diastolic lengths in both regions. However, GBE increased right ventricular stroke work compared with PAC. We conclude that end-diastolic segment lengths reflect true volume changes of the right ventricle. Furthermore, during acute pressure overload, the right ventricle dilates to compensate for the afterload change. However, ventricular function is better maintained after GBE.

Animals↗

Left and right ventricular function in porcine Escherichia coli sepsis.

In anesthesized pigs, hemodynamic measurements and gated bloodpool scintigraphy were performed during and after infusion of live Escherichia coli (2 X 10(8)/kg). Ejection fractions (EF) as well as the relation between end-diastolic volumes (EDV) and stroke work (SW) were used to evaluate changes in left (LV) and right ventricular (RV) function. Porcine E. coli sepsis proved to be characterized by pulmonary vascular hypertension (PVH) and systemic arterial hypotension, accompanied by a reflex increase in heart rate. Systemic flow remained essentially unchanged. E. coli infusion resulted in pronounced and opposite changes in LV and RV preload. RVEDV increased initially and then returned to the value observed before E. coli infusion. LVEDV showed a continuous decrease during the observation of 3 hours. Alterations in LVSW and RVSW appeared to parallel the changes in LVEDV and RVEDV. No significant changes in LVEF and RVEF were found. It is concluded that porcine E. coli sepsis might be a suitable model for human sepsis complicated by PVH. In this animal model no clear signs of myocardial depression or evidence of right heart failure were observed.

Animals↗

Surgical treatment of patients with ischemic cardiomyopathy: the significance of right ventricular function.

BACKGROUND: Patients with ischemic cardiomyopathy (ICMP) awaiting heart transplantation (HT) have a high mortality rate, in part because of the lack of donor organs. Given this limitation, we propose to broaden the indications for coronary artery bypass grafting (CABG) in this group and to more accurately select patients with ICMP requiring myocardial revascularization or HT. In this study, we assessed the short and long-term results of CABG in patients with ICMP. We also assessed the role of the right ventricle and the diastolic function of both ventricles in patients with ICMP. Using this information, we propose indications for CABG and/or HT in patients with ICMP. METHODS: We analyzed 49 patients with ICMP undergoing workup as potential heart transplant candidates. The patients were divided into two groups. Group A included 19 patients submitted to isolated CABG based on the preoperative assessment of myocardial viability. Group B consisted of 30 patients determined to be best suited for HT (with five patients actually receiving a donor heart). All patients were assessed by radionuclide ventriculography (RVG) and functional testing in order to assess their myocardial viability. RVGs were obtained prior to coronary bypass as well as at two and twelve months postoperatively. RESULTS: Preoperative data in group A were: left ventricular end-diastolic dimension (LVEDD) 7.0+/-0.32 cm, left ventricular ejection fraction (LVEF) 24.2+/-2.6%, and right ventricular ejection fraction (RVEF) 32.4+/-2.6%. For Group B, LVEDD was 7.7+/-0.29 cm, LVEF was 22+/-2.7%, and RVEF 26+/-2.6%. The operative mortality in group A was 16.6%. Three patients died in the early postoperative period, two of them due to acute cardiac failure, and one due to cerebral complications. The number of grafted arteries was 3.6+/-0.2. One year after coronary artery bypass, the resting LVEF increased to 33.3% (a 36% improvement compared with preoperative, p < 0.001). Three-year survival was 77% in group A and 26.8% in group B. Examination of the myocardial functional state after CABG showed that the LV diastolic and RV systolic parameters statistically improved. The decrease of RVEF was revealed in the orthostatic test in patients (group A) who died after CABG in the early postoperative period, and in group B that correlated with their parameters of the myocardial viability. CONCLUSIONS: CABG in the patients with ICMP significantly increases the functional reserves of the myocardium of both ventricles, mostly because of the improvement in the diastolic function of the LV. In the RV, the systolic function could restore even in the early postoperative period. Preoperative analysis of the parametric images made after orthostatic test and nitroglycerin intake allow prediction, with 85 % sensitivity and 95% specificity, of the areas of the myocardium which will restore their function immediately after CABG ("hibernated myocardium"). The recovery of regional wall motion amplitude and of the response of the myocardium to coronary revascularization could continue during the first year after revascularization ("stunned myocardium "), most often beginning in the LV. The decrease of the EF of the RV as a response to the "unloading" tests could be a result of the disturbance of the ventricles' interaction as well as the spreading of the scarring of the RV myocardium. This decrease could be a predictor of the possible development of the low cardiac output syndrome after CABG.

Adult↗

Effect of digoxin on right ventricular function in severe chronic airflow obstruction. A controlled clinical trial.

The effect of digoxin on the right and left ventricular ejection fractions in 15 patients with pulmonary heart disease caused by severe chronic airflow obstruction was studied in a double-blind, randomized, placebo-controlled trial. All patients were ambulatory and had clinical features of right but not left ventricular dysfunction. Equilibrium radionuclide angiography showed reduced right ventricular ejection fraction in all patients and reduced left ventricular ejection fraction in four. After 8 weeks of digoxin treatment, the abnormal left ventricular ejection fractions were normal; right ventricular ejection fractions increased only in those patients who had had abnormal left ventricular ejection fractions. We conclude that in patients with pulmonary heart disease, the right ventricular ejection fraction is abnormal and improves with digoxin treatment only when the left ventricular ejection fraction also is initially abnormal.

Aged↗

Norepinephrine and phenylephrine effects on right ventricular function in experimental canine pulmonary embolism.

In a canine model of pulmonary embolism (PE) produced by infusion of autologous blood clots, mean arterial blood pressure (MAP) decreased to 73 +/- 4 mm Hg while cardiac output (CO) decreased to less than 50 percent of baseline. Intravenous infusion of phenylephrine (PHEN) and norepinephrine (NE) restored MAP to somewhat above baseline values. However, only NE restored CO to control levels. The right ventricular myocardial blood flow increased 15 percent in the PE group with PHEN and 229 percent with NE at equipressor concentrations. The right ventricular myocardial oxygen consumption (RVMVo2) was not significantly different between PE and PE + PHEN while PE + NE increased RVMVO2 by 144 percent to 20.2 +/- 1.8 ml/min/100 g. The RV output was not adequately restored with PE, but when RV contractility was augmented with NE, RV output was restored to baseline. Right ventricular minute work increased 100 percent with NE and was maintained with a 100 percent increase in oxygen consumption. Calculated pulmonary vascular resistance (PVR) was decreased during PE by 36 percent with PE + PHEN while PVR in NE-treated dogs decreased by 59 percent. In NE-treated animals, systemic vascular resistance (SVR) was restored to control levels while in PHEN-treated animals SVR increased about 75 percent from baseline. We conclude that the salutary effects of NE on RV output are due to both alpha and beta receptor stimulation, which increased contractility, RVMBF, and RVMVo2, and decreased both PVR and SVR. In the PHEN-treated dogs, our indices of minute-work, RVMBF, and RVMVo2 suggest that coronary autoregulation was intact; however, there was no apparent benefit to RV output. This study suggests that in the clinical setting of acute PE, the judicious use of NE, rather than PHEN, may be more beneficial in restoring RV function and systemic hemodynamics.

Animals↗

Relation between right ventricular enlargement, QRS duration, and right ventricular function in patients with tetralogy of Fallot and pulmonary regurgitation after surgical repair.

OBJECTIVE: In patients with repaired tetralogy of Fallot, to examine (1) a possible relation between right ventricular enlargement and QRS prolongation, and (2) the effect of right ventricular enlargement caused by pulmonary regurgitation on the right ventricular ejection fraction, evaluated by three dimensional echocardiography, and global function, evaluated by the myocardial performance index. DESIGN AND PATIENTS: 40 patients with repaired tetralogy were studied. Right ventricular volumes were derived from three dimensional echocardiographic data after this method had been validated by comparison with magnetic resonance imaging in 21 patients. Ejection fraction was calculated from end diastolic and end systolic volumes. The Doppler derived myocardial performance index was measured in all patients. Measured data were correlated with QRS duration. SETTING: Tertiary cardiac centre for congenital heart disease. RESULTS: There was good agreement between three dimensional echocardiographic and magnetic resonance assessment of right ventricular volumes and ejection fraction. The z score of the right ventricular end diastolic volume and ejection fraction of all patients was 1.35 and -4.15, respectively. Patients with severe pulmonary regurgitation had a lower right ventricular ejection fraction (p < 0.01) and an increased myocardial performance index (p < 0.01) compared with patients with mild to moderate pulmonary regurgitation. The correlation between ejection fraction and right ventricular end diastolic volume was r = -0.35 (p < 0.05). The mean (SD) QRS duration was 131.89 (25.69) ms, range 80-180 ms. The correlation between QRS duration and right ventricular end diastolic volume was r = 0.6 (p < 0.01). CONCLUSIONS: There is a correlation between the right ventricular size obtained by three dimensional echocardiography and QRS duration on the surface ECG, indicating mechanoelectrical interaction. The severity of pulmonary regurgitation has a negative influence on right ventricular ejection fraction and combined systolic and diastolic global function, as assessed by myocardial performance.

Adolescent↗

Right ventricular function late after total repair of tetralogy of Fallot.

Over the past decades, life expectancy in patients with congenital heart disease has increased dramatically. However, serious complications may develop late after total repair in infancy. These complications are usually the result of longstanding pulmonary regurgitation, which leads to dilatation of the right ventricle and an increased risk for severe arrhythmias. Therefore lifelong follow-up in these patients is required. Cardiac magnetic resonance imaging is the current imaging tool of choice because it offers superior imaging quality and enables accurate quantification of functional parameters such as flow volumes and systolic and diastolic performance.

Humans↗

Right ventricular function in rats with hypoxic pulmonary hypertension.

The function of the hypertrophic right ventricle (RV) was studied in adult rats with hypoxic pulmonary hypertension induced by intermittent high-altitude (IHA) exposure. The isolated RV working heart preparation that was employed enabled us to estimate ventricular contractile and pump performance under controlled loading conditions. In rats exposed to IHA hypoxia the elevated RV systolic pressure and maximum rate of pressure development were observed at various levels of preload or afterload. The peak indices of mechanical performance were almost doubled in these animals when compared with the normoxic group, while the index of contractility remained unchanged. Maximum ventricular performance was found to be a linear function of the relative RV weight. No evidence of RV pump dysfunction was detected in rats exposed to IHA; moreover, the ability of the ventricle to maintain cardiac output against increased pulmonary resistance was markedly improved. The prevention of tricuspid regurgitation by using an artificial valve did not influence the functional curves and the peak ventricular performance. The regression of hypertrophy was accompanied by a reversal of ventricular function to control values, except for the persisting slight increase of peak RV pressure. It may be concluded that the increase of the RV mass in IHA-exposed rats serves to improve maximum ventricular performance, which aids in overcoming and elevated pulmonary resistance without disturbing the pump function.

Altitude Sickness↗

[Comparison of right ventricular function between prevention and enlargement of pulmonary valve annulus after repair of tetralogy of Fallot; mid-term results].

Total of 41 patients with tetralogy of Fallot (TOF) who underwent intracardiac repair from 1993 to 1998 were divided into 2 groups: preservation (n = 14) or enlargement (n = 27) of the pulmonary valve annulus. The procedure was decided on the Z value of the annular size: above or under -2 SD of the standard value. Although postoperative right ventricular (RV) diastolic volume (RVEDV) and cardiothoracic ratio (CTR) were larger than the preservation group and pulmonary regurgitation (PR) existed in the enlargement group, RV pressure was decreased and central venous pressure (CVP) was low and RV contraction was preserved. The exercise capacity was also good and no significant arrhythmia was recognized. Our mid-term results showed that appropriate enlargement of the pulmonary valve annulus preserved good RV function in patients with TOF.

Cardiac Surgical Procedures↗

[Right ventricular function during and after aortocoronary bypass].

A transient depression of right ventricule (RV) function following aortocoronary bypass operation is a common event. Occasionally, RV failure may be responsible for postoperative low cardiac output syndrome, cardiogenic shock or intracardiac right-left shunt. Understanding and monitoring of RV function is essential for proper management of patients during and after aortocoronary bypass operation.

Coronary Artery Bypass↗

Effects of amrinone on left and right ventricular function in patients with impaired myocardial performance during general anaesthesia.

We have studied the effects of amrinone on left and right ventricular haemodynamics in patients with impaired ventricular performance caused by coronary artery disease. Anaesthesia was achieved with fentanyl, flunitrazepam and pancuronium. After reaching steady state, a bolus dose of amrinone 0.5 mg kg-1 was administered followed by an infusion of 1 mg kg-1 h-1. Right ventricular ejection fraction (RVEF) and other haemodynamic variables were evaluated at six times: before, 5, 10, 15, 20 and 30 min after bolus administration of amrinone. Amrinone led to a 23% increase in cardiac index resulting mainly from reduction in afterload. While central venous pressure and mean pulmonary artery pressure remained unchanged, RVEF increased by 28%. This effect may be interpreted as an improvement in right ventricular performance.

Adult↗

Effects on right ventricular function of a change from dopamine to dobutamine in critically ill patients.

In 15 critically ill patients requiring adrenergic support, right ventricular ejection fraction (RVEF) and right ventricular (RV) volumes were measured by the thermodilution technique receiving 5 micrograms/kg.min of dopamine and after replacement by the same dose of dobutamine. Shift from dopamine to dobutamine resulted in significant increases in stroke index from 28.1 +/- 3.6 to 31.0 +/- 3.8 ml/m2 (p less than .01) and significant decreases in pulmonary artery balloon-occluded pressure from 15.1 +/- 1.0 to 13.9 +/- 1.2 mm Hg (p less than .05) and right atrial pressure (RAP) from 14.0 +/- 1.3 to 12.2 +/- 1.1 mm Hg (p less than .05). RVEF increased slightly but significantly from 21.5 +/- 2.7% to 23.7 +/- 2.9% (p less than .01) so that RV end-diastolic volume (RVEDVI) was unchanged (140 +/- 12 vs. 141 +/- 12 ml, nonsignificant). RVEDVI/RAP ratio increased from 11.3 +/- 1.0 to 12.9 +/- 1.1 ml/mm Hg (p = .037). These results support the view that dobutamine has more favorable effects on RV function than dopamine in critically ill patients in the absence of profound hypotension and also indicates that higher filling pressures under dopamine administration can be related to changes in ventricular pressure/volume relationship.

Adult↗

Pulmonary hypertension after transjugular intrahepatic portosystemic shunt: effects on right ventricular function.

The short- and mid-term hemodynamic effects of transjugular intrahepatic portosystemic shunt (TIPS) were studied in 16 sedated cirrhotic patients. Indications included relapsing variceal bleeding (n = 10) and refractory ascites (n = 6). The decrease of porto-atrial pressure gradient (from 20.4 +/- 4.2 mm Hg to 10.1 +/- 2.4 mmHg; P < .05) was associated with an increase of mean pulmonary artery pressure (MPAP) (from 12.3 +/- 3.0 mm Hg to 20.3 +/- 5.3 mm Hg; P < .05) and of right atrial pressure (RAP) from 3.4 +/- 2.6 mm Hg to 8.3 +/- 3.7 mm Hg; P < .05), whereas right ventricular end-diastolic volume (RVEDVI) remained unchanged. The significant increase of cardiac index (CI) (from 4.5 +/- 1.2 L/min/m2 to 5.0 +/- 1.1 L/min/m2; P < .05) was essentially attributable to an increase of heart rate (HR) (from 81 +/- 11 to 88 +/- 10 beats/min; P < .05). Systemic vascular resistance (SVR) decreased (from 812 +/- 281 to 666 +/- 191 dynes/sec/cm5; P < .05), whereas pulmonary vascular resistance (PVR) increased (from 60.6 +/- 29.6 to 82.0 +/- 34.6 dynes/sec/cm5; P < .05). After transient shunt occlusion with a balloon catheter, all of the hemodynamic parameters returned to baseline values, except pulmonary artery pressure, which also decreased but remained significantly increased. One month after TIPS, pulmonary pressure remained elevated, and CI further increased. It is concluded that increased PVR is the major hemodynamic alteration occurring after TIPS placement. It correlates with the decrease of porto-atrial gradient and is probably mediated by both mechanical and neurohumoral factors.

Adult↗

Pressure-flow relations in the pulmonary artery during myocardial ischaemia: implications for right ventricular function in coronary disease.

Because exercise induced pulmonary hypertension may disturb optimal coupling between the right ventricle and pulmonary artery in coronary artery disease, high fidelity pulmonary artery and right ventricular pressure and electromagnetic pulmonary artery flow velocity data were recorded at rest and during supine exercise in 10 control subjects free of detectable cardiovascular disease and in 11 patients with coronary artery disease. The pulmonary artery impedance and power spectra were calculated from Fourier analysis of pressure and flow waveforms. Total hydraulic power expended per unit of forward flow was computed as an index of right ventricular-pulmonary artery coupling. In coronary artery disease exercise produced substantial increases in pulmonary artery pressure, pulmonary artery characteristic impedance, and total power per unit flow. These changes did not occur in control subjects. Despite a significant exercise increase in right ventricular end diastolic pressure and peak right ventricular dP/dt, and independent of the presence of right coronary artery involvement, the right ventricular stroke output response during exercise was significantly blunted in the coronary artery disease patients. Pulmonary vascular resistance was unchanged by exercise in either group. Exercise induced ischaemia presents an increased pulsatile hydraulic load to the right ventricle. Increased pulmonary artery input impedance impairs the hydraulic efficiency of right ventricular-pulmonary artery coupling and may contribute to the limitation of right ventricular ejection performance in coronary artery disease.

Adult↗