Left ventricular pump function in right ventricular overload

To clarify how left ventricular pumping action is altered in cor pulmonale, an experimental study was performed using canine heart preparations in which the effects on left ventricular performance of right ventricular overload, with and without depressed systolic function, were investigated. For this purpose, two methods using excised perfused hearts (n = 16) and in vivo hearts (n = 6) were employed, and in the latter condition, pulmonary artery constriction (n = 7), femoral arterial-venous (A-V) shunt (n = 3) and right coronary artery occlusion (n = 6) were induced. Left ventricular systolic function was assessed by the relationship between left ventricular isovolumic developed pressure and left ventricular volume in excised heart, and by ejection fraction with 2 dimensional echocardiogram in the vivo condition, taking into account preload and afterload changes. From the excised heart preparation, it was shown that left ventricular developed pressure significantly decreases when right and left ventricular diastolic pressure increases greatly. On the other hand, in vivo right ventricular overload due to pulmonary constriction and A-V shunt, the left ventricular ejection fraction increased following afterload reduction. When we compare the left ventricular ejection fraction in pulmonary constriction with that in right coronary occlusion, in which reduction of left ventricular diastolic area from the control was similar, the latter was significantly decreased despite afterload reduction. These results suggest that right ventricular overload does not necessarily induce left ventricular systolic dysfunction unless left ventricular end-diastolic pressure, as well as that of the right ventricle, increases definitely and simultaneously.(ABSTRACT TRUNCATED AT 250 WORDS)     

Left ventricular inotropic reserve and right ventricular function predict increase of left ventricular ejection fraction after beta-blocker therapy in nonischemic cardiomyopathy.

OBJECTIVES: The purpose of this study was to determine whether higher left ventricular inotropic reserve, defined as the increase in left ventricular ejection fraction (LVEF) in response to intravenous dobutamine infusion, or other ventriculographic variables predict the increase in LVEF after beta-blocker therapy in patients with nonischemic cardiomyopathy (NICM). BACKGROUND: Long-term beta-blocker therapy increases LVEF in some patients with NICM. Other than dose, there are no definite predictors of LVEF increase. METHODS: Thirty patients with LVEF < or = 0.35 and NICM underwent assessment of LVEF at rest and after a 10-min intravenous infusion of dobutamine at 10 microg/kg/min, using equilibrium radionuclide ventriculography. Age was 49 +/- 11 years, 33% women, functional class 2.6 +/- 0.5, duration of chronic heart failure 3.2 +/- 2.9 years, LVEF 0.21 +/- 0.07, left ventricular end-diastolic volume index 180 +/- 64 ml/m2. Right ventricular ejection fraction (RVEF) was abnormal in 37%. Mean dobutamine-induced augmentation of LVEF (DoALVEF) was 0.12 +/- 0.08. Patients were started on one of three beta-blockers (carvedilol, bucindolol or metoprolol) and the dose was advanced to the maximum tolerated. RESULTS: Left ventricular ejection fraction, reassessed 7.4 +/- 5.9 months after maximum beta-blocker dose was reached, increased to 0.34 +/- 0.13 (p = 0.0006). The following baseline variables correlated with improvement of LVEF: DoALVEF (p = 0.001), RVEF (p = 0.005), systolic blood pressure at end of dobutamine infusion (p = 0.02) and dose of beta-blocker (p = 0.07). In a multivariate analysis, only DoALVEF (p = 0.0003) and RVEF (p = 0.002) were predictive of the increase in LVEF. CONCLUSIONS: Patients with nonischemic cardiomyopathy who have higher left ventricular inotropic reserve and normal RVEF derive higher increase in LVEF from beta-blocker therapy.     

Left ventricular dimensions and function during exercise in dogs with chronic right ventricular pressure overload

Left ventricular (LV) dimensions and shortening at rest and during treadmill exercise were examined before and after 4 weeks of pulmonary artery (PA) constriction in 6 conscious dogs. The dogs were preinstrumented with LV and right ventricular (RV) catheters, an LV micromanometer, a PA inflatable cuff occluder and ultrasonic crystals to measure an LV anteroposterior, a septal-lateral, an apex-base and a free wall segment chord. With PA constriction, RV pressures increased from $\text{49 ±}\text{4}\text{2}\text{± 1 mm}$ Hg (systolic/end-diastolic) to $\text{104 ±}\text{5}\text{2}\text{± 1}$ at rest and from $\text{71 ±}\text{9}\text{2}\text{± 1}\text{to}\text{133 ±}\text{8}\text{14}\text{± 2}$ at peak exercise (mean ± standard error of the mean). Heart rate, LV pressure and LV dP/dt were similar before and after RV pressure overload at rest and with exercise. During exercise at control, systolic shortening increased significantly in all chords. With chronic PA constriction at rest, shortening of all chords also remained normal despite decreases in end-diastolic dimensions, which were most marked in the septal-lateral chord (23% decrease, p <0.01). However, during exercise in the presence of RV pressure overload, septal-lateral shortening decreased 46% (p <0.01) despite increases in systolic shortening in the other chords similar to the control response. Therefore, although LV function at rest in chronic RV pressure overload is normal, exercise may induce regional abnormalities of LV contraction that appear to be mediated by a reduced contribution of the ventricular septum to LV ejection.     

Early improvement in left ventricular diastolic function after relief of chronic right ventricular pressure overload

Chronic right ventricular pressure overload is associated with left ventricular diastolic dysfunction. Whether or not an abrupt reduction in pulmonary artery pressure in patients with chronic pulmonary hypertension results in early improvement of left ventricular diastolic function is unknown. To assess this, the Doppler indexes of left ventricular diastolic function and echocardiographic measures of left ventricular volume were analyzed in 22 patients (age, 41 +/- 14 years, mean +/- SD) before and within 1 week after pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension. Mean duration of cardiopulmonary symptoms was 37 months (range, 4 months to 9 years). After operation, mean pulmonary artery pressure and pulmonary vascular resistance decreased (50 +/- 13 to 29 +/- 9 mm Hg and 904 +/- 654 to 283 +/- 243 dynes.sec/cm5, respectively, both p less than 0.001), pulmonary artery wedge pressure was unchanged (11 +/- 5 to 12 +/- 5 mm Hg), and cardiac index increased (2.0 +/- 0.5 to 2.8 +/- 0.7 l/min/m2 p less than 0.001). Left ventricular end-diastolic volume and stroke volume increased significantly (58.5 +/- 18.0 to 76.6 +/- 25.0 ml and 30.3 +/- 12.3 to 41.8 +/- 12.5 ml, respectively, both p less than 0.001) after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Poor correlation between left and right ventricular ejection fractions in patients with normal ventricular function

BACKGROUND AND OBJECTIVE:     

Left ventricular behavior following acute right ventricular pressure overload: an experimental study]

Relationships between biventricular pressures, left ventricular shape and paradoxical septal motion in patients with right ventricular pressure overload (RVPO) are unknown. To clarify these relationships, we measured left and right ventricular short-axis dimensions and ventricular pressures using anesthetized open-chest dogs with pulmonary embolizations. With repeated microembolization, right ventricular systolic pressure (RVSP) increased stepwise from a level of 27 mmHg to the maximum value of 72 mmHg. This elevation caused gradual leftward shift of the interventricular septum (IVS) both at end-diastole and end-systole. Further embolization caused collapse (shock: left ventricular systolic pressure: LVSP < 70 mmHg) with a fall in RVSP. In the state of shock, the rise in right ventricular end-diastolic pressure (RVEDP) and fall in left ventricular end-diastolic pressure (LVEDP) were prominent, and the degree of shift of the IVS became significantly greater at end-diastole than at end-systole, resulting in paradoxical motion of the IVS. There were significant linear relationships between the degree of end-diastolic IVS displacement and end-diastolic transseptal pressure (LVEDP-RVEDP), and between the degree of end-systolic IVS displacement and end-systolic transseptal pressure (LVESP-RVESP) throughout the course of repeated pulmonary microembolization even in the state of shock. In conclusion, abnormal movements of the IVS in RVPO patients indicate the presence of a marked decrease in end-diastolic transseptal pressure due to right ventricular failure.     

Estimation of left ventricular function in right ventricular volume and pressure overload. Detection of early left ventricular dysfunction by Tei index.

Although the effects of right ventricular (RV) volume and pressure overload (RVVO and RVPO) on ventricular septal motion are different, the differential effect on left ventricular (LV) function is still controversial. The Doppler-derived index (Tei index) combining systolic and diastolic ventricular function, defined as the sum of isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) divided by ejection time (ET), has been demonstrated to be a useful index to estimate LV function and to predict the prognosis of patients with congestive heart failure. This study was designed to evaluate the differential effects of RVVO and RVPO on LV function using the Tei index. Study patients consisted of 26 age-matched normal subjects, 22 patients with atrial septal defect (ASD) with normal or borderline RV pressure and 25 with primary pulmonary hypertension (PPH). All subjects had normal LV ejection fractions measured with 2-dimensional echocardiogram using biplane Simpson's method (61 +/- 4 vs 61 +/- 4 vs 63 +/- 8%, normal vs ASD vs PPH). Tei index was easily obtained in all subjects from transthoracic Doppler echocardiogram of LV inflow and outflow. Patients with ASD had normal ICT, IRT and ET, resulting in normal Tei index, however, patients with PPH had significantly prolonged ICT and IRT with shortened ET, resulting in a significant increase in Tei index (0.38 +/- 0.04 vs 0.36 +/- 0.03 vs 0.61 +/- 0.22, p < 0.001). Although RVVO due to ASD has no significant effects on LV function, RVPO due to PPH can adversely affect LV function. The Tei index is a simple and sensitive measure to assess LV function caused by RVVO or RVPO.     

Comparison of single plane videodensitometry-based right ventricular ejection fraction in right and left anterior oblique views to biplane geometry-based right ventricular ejection fraction

To evaluate the reliability of the videodensitometric assessment of right ventricular ejection fraction, 38 patients were studied during diagnostic cardiac catheterization. Digital subtraction images of the right ventricle were obtained in both the right anterior oblique and the left anterior oblique views, using direct intraventricular injection of dilute contrast medium. From the end-diastolic and end-systolic images obtained in each view, analysis of the relative brightness values generated a videodensitometry-based right ventricular ejection fraction for both the right and the left anterior oblique views. These values were compared with those generated by applying the geometry-based Simpson's rule to the orthogonal images. Right ventricular ejection fraction ranged from 22 to 88%. Videodensitometric ejection fraction in the right anterior oblique view correlated well with that in the left anterior oblique view (r = 0.88) and each correlated well with geometry-based ejection fraction (r = 0.91 and 0.82, respectively). In a subset of 18 patients without significant cardiac disease, mean videodensitometric right ventricular ejection fraction was 68% (versus 61% in the abnormal subset), and it correlated closely with left ventricular ejection fraction (r = 0.82). Videodensitometric analysis of digital subtraction images provides a reliable method for calculating right ventricular ejection fraction that is independent of geometry and reliably separates normal from abnormal values. Application of videodensitometric techniques should simplify analysis of the response of the right ventricle to different interventions in patients with cardiac disease.     

Left ventricular geometry and survival in patients with normal left ventricular ejection fraction

In hypertensive populations, left ventricular (LV) geometry, which is characterized by hypertrophy, predicts cardiovascular outcome. The left ventricle can also alter its shape by concentric remodeling (CR) in the absence of LV hypertrophy, a feature that is detected by echocardiography. This study assessed the prevalence and prognostic significance of various forms of LV geometry and changes in LV geometry over time in patients with normal LV systolic function. Retrospective analysis of a large clinical population (n = 35,602) that was referred for echocardiography was done, with all-cause mortality as the primary outcome. Abnormal LV geometry was identified in 46% of patients, with CR present in 35% (n = 12,362) and LV hypertrophy in 11% (n = 3,958). Patients with abnormal LV geometry were older and more obese compared with subjects with normal LV geometry. There was a strong relation between abnormal LV geometry and mortality, and patients with CR and LV hypertrophy exhibited considerably higher relative risk for all-cause mortality compared with subjects with normal LV geometry (relative risk [RR] 1.99, 95% confidence interval [CI] 1.88 to 2.18, p <0.0001; RR 2.13, 95% CI 1.89 to 2.40, p <0.0001, respectively). Subjects with CR who reverted to a normal geometric pattern had improved survival (RR 0.64, 95% CI 0.42 to 0.97, p = 0.03) compared with those who progressed to LV hypertrophy (RR 1.54, 95% CI 1.01 to 2.47, p = 0.05). In conclusion, CR, a form of cardiac adaptation, is frequently noted in patients with normal LV ejection fractions and confers a risk of death similar to that of LV hypertrophy. Normalization of CR is associated with better survival, whereas transition to LV hypertrophy increases mortality.     

Left ventricular end-diastolic pressure in evaluating left ventricular function

There are several factors that could affect the left ventricular end-diastolic pressure. These include heart rate, preload, afterload, pericardial or pleural pressure, diastolic properties of the left ventricle, and the left ventricular inotropic state. Recognition of these factors appears important when considering the left ventricular end-diastolic pressure as an index of left ventricular function.     

Angiographic right and left ventricular function in arrhythmogenic right ventricular dysplasia

We prospectively documented right ventricular (RV) and left ventricular (LV) volumes and ejection fractions in a large series of patients with arrhythmogenic RV dysplasia/cardiomyopathy (ARVD/C). Eighty-five patients with ARVD/C and 11 controls underwent 2 successive orthogonal right and left monoplane x-ray-digitized cineangiographies. Volumes were calculated using the hemielliptical RV and ellipsoidal LV models. All controls and 58 of 85 patients (ARVD/C-I) had a RV ejection fraction > or =35% and 27 patients had a RV ejection fraction <35% (ARVD/C-II). Tricuspid annulus plane systolic excursion (TAPSE) was lower in ARVD/C-II than in ARVD/C-I patients (6 +/- 3 vs 14 +/- 3 mm) and controls (16 +/- 2 mm) (each p <0.001). In patients with ARVD/C, TAPSE was positively related to RV ejection fraction (r = 0.79) and to crista supraventricularis shortening (r = 0.81) (each p <0.001). Sensitivity and specificity of TAPSE <12 mm in identifying patients with RV ejection fraction <35% were 96% and 78%, respectively. LV ejection fraction was > or =50% in 68 patients, 40% to 49% in 10, and <40% in 7. Diffuse RV outflow tract aneurysm was observed in 9 patients, all belonging to ARVD/C-II, and this sign identified patients with LV ejection fraction <40% with 86% sensitivity and 96% specificity. In conclusion, 68% of ARVD/C patients had normal RV ejection fraction and RV volumes, and 80% of ARVD/C patients had normal LV ejection fraction. Decreased TAPSE <12 mm and a diffuse RV outflow tract aneurysm were sensitive and specific indicators of RV ejection fraction <35% and LV ejection fraction <40%, respectively.     

Left ventricular thrombi in the presence of normal left ventricular function

We report two cases of left ventricular thrombi identified by routine echocardiography in the presence of normal ventricular function to highlight the rarity and clinical significance of this condition. A 14-year-old boy, positive for anticardiolipin and antinuclear antibodies, was found to have a left ventricular thrombus. A 30-year-old male, who presented with a transient ischemic attack, was found to have hypereosinophilic syndrome and a mobile left ventricular thrombus. The thrombi disappeared in both patients after a few days of anticoagulant therapy without symptoms of embolization.     

Left ventricular function during and after right ventricular pacing

OBJECTIVES: The aim of this research was to evaluate right ventricular pacing effects on left ventricular function. BACKGROUND: Right ventricular pacing alters the ventricular activation sequence and reduces left ventricular ejection fraction (EF). It is unclear whether the observed reduction in EF can be completely attributed to the alteration in activation sequence. METHODS: Twelve subjects (eight women), mean age 68 +/- 12 years, with transvenous dual-chamber pacemakers, normal left ventricular function, and intact atrioventricular (AV) conduction were studied with serial-gated blood pool studies. Left ventricular EF was measured at a fixed rate after at least 1 week of atrial pacing only (baseline), during short-term (2 h) and mid-term (1 week) AV sequential pacing with a short AV delay, and after short- and mid-term AV pacing. RESULTS: Baseline EF was 66.5 +/- 4.5%. Short-term AV pacing resulted in a decrease in EF to 60.3 +/- 5.2% (p < 0.0002). After one week of AV pacing, there was a further decline in EF to 52.9 +/- 8.3% (p < 0.0001). After cessation of mid-term pacing, EF was 57.3 +/- 5.9% (p < 0.0001 vs. baseline). A total of 2, 5, 8, and 24 h later, EF remained depressed (59% to 60%, p < 0.007). At 32 h, EF was 62.9 +/- 7.6% (p < 0.11 compared with baseline). CONCLUSIONS: The abnormal activation sequence resulting from right ventricular pacing accounts for only part of the reduction in EF as mid-term pacing is associated with a lower EF than short-term pacing, and EF remains depressed after cessation of AV pacing. Changes in ventricular function induced by right ventricular pacing may account for some of its associated adverse effects.     

Left and right ventricular function in acromegalic patients

Recent studies have proved close relations between cardiovascular and endocrinic systems. This relation has been observed in acromegaly, the disease connected with unrestrained secretion of growth hormone. The aim of the study was to assess Holter monitoring and echocardiography of acromegalic patients. The study group consisted of 28 acromegalic patients, including 15 patients with hypertension, was considered. As control groups we examined 20 patients with essential hypertension and 20 normotensive healthy subjects: All subjects underwent twenty-four hour Holter recordings, complete M-mode, two-dimentional and spectral Doppler echocardiography. Ventricular premature complexes occurred in 65% of acromegalic patients. Frequency and severity of ectopic beats were significantly increased compared to control groups. Left ventricular ejection fraction was considered to be normal, although significant decreased compared to healthy subjects. Left ventricular mass was above normal value in acromegalic patients--no significant difference was found between hypertensive and normotensive acromegalics. Doppler examination has shown the abnormalities of left and right ventricular filling in 89% of acromegalics. We have observed the correlations between left and right ventricular filling indices and the duration of the disease, and left ventricular mass. Left ventricular hypertrophy frequently occurs in acromegalic patients and this is not simply secondary to systemic hypertension. The prevalence of ventricular arrhythmias in acromegalic patients seems to be associated with left ventricular hypertrophy. Doppler examination suggests impaired left and right diastolic filling in patients with acromegaly.     

Effect of ventricular function on left ventricular ejection time in aortic stenosis

Since recognition of factors which modify the duration of ejection in aortic stenosis is of clinical importance, the relations among rate-corrected left ventricular ejection time, aortic valve area, and determinants of ventricular performance were studied in 54 catheterised patients. In patients with a normal cardiac index, increasing duration of ejection was linearly related to increasing obstruction. In patients with failing ventricles, on the other hand, the ejection time was less prolonged, and the duration of ejection was unrelated to valve area. At fixed valve area, relation with cardiac output, stroke volume, heart rate, mean aortic valve pressure gradient, mean aortic pressure, and left ventricular end-diastolic pressure could not adequately explain the observed scatter in ejection time. This suggests a multifactorial basis for the wide range of ejection times observed with severe aortic stenosis.     

Relation of right ventricular ejection fraction to exercise capacity in chronic left ventricular failure

Although the left ventricle is traditionally viewed as the heart's main pumping chamber, no correlation has been shown between left ventricular (LV) ejection fraction (EF) at rest and exercise capacity in patients with chronic LV failure. Because vasodilators with venodilating activity increase exercise capacity more than predominant arterial dilators in patients with LV failure, right ventricular (RV) function may relate to exercise capacity in these patients. In 25 patients with chronic LV failure, caused by coronary artery disease in 12 patients and idiopathic dilated cardiomyopathy in 13 patients, RVEF and LVEF at rest were measured by radionuclide angiography. Maximal upright bicycle exercise testing was also performed to determine maximal oxygen consumption, which averaged only 13 ± 4 ml/min/kg. The LVEF at rest was 26 ± 10% and did not correlate with maximal oxygen consumption (r = 0.08). However, the RVEF was 41 ± 12% and correlated with maximal oxygen consumption (r = 0.70, p < 0.001) in the same patients. The correlation was stronger (r = 0.88) in patients with coronary artery disease than in those with idiopathic dilated cardiomyopathy (r = 0.60). Thus, RVEF at rest is more predictive of exercise capacity than LVEF in the same patients with chronic LV failure. These results are consistent with the clinical observation that only venodilating agents increase exercise capacity of patients with chronic LV failure.