Influence of right ventricular stimulation site on left ventricular function in atrial synchronous ventricular pacing

Septic shock is a dangerous condition with high mortality rates. In sepsis, the inducible form of nitric oxide (NO) synthase is induced, releasing high amounts of NO. Glucocorticoids have potent anti-inflammatory properties and are very effective in inhibiting the induction of this enzyme if administered before the shock onset. It is known that glucocorticoid receptor (GR) has critical cysteine residues for steroid binding in its hormone-binding and DNA-binding domains. It has also been reported that NO reacts with ---SH groups, forming S-nitrosothiols. Therefore, we examined the potential effect of NO on the ligand-binding ability of GR. NO donors (S-nitroso-acetyl-DL-penicillamine, S-nitroso-DL-penicillamine, or S-nitroso-glutathione) decreased, in a time- and dose-dependent manner, the binding of [3H]triamcinolone to immunoprecipitated GR from mouse L929 fibroblasts. The nonnitrosylated parent molecules, N-acetyl-DL-penicillamine, and reduced gluthatione were without effect. Scatchard plots revealed that the number of ligand binding sites and Kd were reduced (50%) by NO donors. Western blot analysis ruled out the possibility that dissociation of GR/heat shock protein 90 heterocomplex or decrease in GR protein would account for the inhibitory effect of NO. Decreased ligand binding to GR was found when NO donors were incubated with intact fibroblasts. Incubation with NO donors also decreased the steroid-induced reduction in [3H]uridine incorporation into RNA. All of these NO effects were inhibited by the thiol-protecting agent dithiothreitol. Therefore, S-nitrosylation of critical ---SH groups in GR by NO with consequent decreases in binding and affinity may be the mechanisms which explain the failure of glucocorticoids to exert their anti-inflammatory effects in septic shock.     

Operative creation of left to right cardiac shunts: pulmonary functional sequelae

The tuberomammillary nucleus, a cluster of cells in the posterior hypothalamus, is the only known source of brain histamine. Although this nucleus is well described in terms of anatomy and neurochemistry, only little is known about its function. In the present study, the effect of a lesion in the region of this nucleus on intracranial self-stimulation was examined. Rats were implanted bilaterally with stimulating electrodes in the lateral hypothalamus and unilaterally with one lesion electrode in the region of this nucleus. After three days of baseline testing, half of the animals were given an electrolytic lesion. The animals were retested for six consecutive days, and thereafter weekly for another seven weeks. From the second day postlesion on, we unexpectedly found a gradual increase in response rate, which peaked on day 13 in the ipsilateral hemisphere only. Although there was no further increase over subsequent days, response rates remained elevated during the following seven weekly tests. The observed increase in lateral hypothalamic self-stimulation after an electrolytic lesion of the tuberomammillary nucleus is discussed in terms of an inhibitory system, possibly located in the region of this nucleus which, when removed by the lesion, increased reinforcing effects of the electrical brain stimulation. The fact that the effects on self-stimulation were lateralized to one hemisphere rules out an interpretation in terms of unspecific "performance" variables that could influence rate of lever pressing.     

Doppler echocardiographic assessment of left atrial and left ventricular function during right bundle branch block]

Electrocardiographic, echocardiographic and Doppler echocardiographic studies were performed in 44 patients with coronary heart disease and complete right bundle branch block. The patients were found to have an impaired phase pattern of left ventricular systole and diastole as more prolonged length of its isometric relaxation and contraction, lower economic feasibility and efficiency of its contraction, moderate dilation and hypertrophy. Hemodynamic abnormalities in the left heart in these patients are closely correlate with the changes in the phase pattern of right ventricular systole and they turn out to be so greater as the degree of its hypertrophy is. In complete right bundle branch block, left ventricular pump dysfunction leads to decreased cardiac output and cardiac index, increased total peripheral vascular resistance, thus predisposing to impaired greater circulation.     

Beta-blocker therapy of severe congestive heart failure in infants with left to right shunts

We report on the clinical and neurohumoral effects of adding low-dose propranolol to conventional therapy with digoxin and diuretics in 6 infants with severe congestive heart failure due to large left-to-right shunts. A significant decrease in heart failure scores and a decrease of the highly activated renin-angiotensin-1 aldosterone system by approximately 70% strongly suggests a beneficial effect of this new therapeutic approach.     

Fontan fenestration closure in the catheterization laboratory--echocardiographic evaluation of residual right to left shunts

This study is a retrospective review using transthoracic echocardiography to assess the success of fenestration closure as well as residual right to left shunts in 35 patients who underwent Fontan fenestration closure in the catheterization laboratory. There is a high rate of closure of the Fontan fenestration; however, other residual right to left shunts are common.     

Echocardiographic features of congenital left ventricular inflow obstruction

The echocardiographic features of congenital left ventricular inflow obstruction are described in six patients. The echocardiograms in two patients with cor triatriatum were distinguished by normal mitral valve motion and an abnormal echo within the left atrium. In two patients with supravalvar mitral ring, in addition to abnormal mitral valve motion, an abnormal echo, presumably originating from the obstructive membrane, was located between the anterior and posterior mitral leaflets. In two cases of parachute mitral valve, mitral valve motion was abnormal. In one of these cases there were multiple mitral valve echoes similar to those found in supravalvar mitral ring. The echocardiographic identification of an obstructive membrane within the left atrium is difficult because of the occurrence of artifacts. However, membranes may be identified if careful scanning techniques are employed in patients in whom left ventricular inflow obstruction is suspected. The echocardiogram is useful in detecting mitral valve abnormalities in these patients and is valuable in cases where mitral valve replacement is contemplated.     

Ventricular interdependence: significant left ventricular contributions to right ventricular systolic function

This article reviews diastolic and systolic ventricular interaction, and clinical pathophysiological conditions involving ventricular interaction. Diastolic ventricular interdependence is present on a moment-to-moment, beat-to-beat basis, and the interactions are large enough to be of physiological and pathophysiological importance. Although always present, ventricular interdependence is most apparent with sudden postural and respiratory changes in ventricular volume. Left ventricular function significantly affects right ventricular systolic function. Experimental studies have shown that about 20% to 40% of the right ventricular systolic pressure and volume outflow result from left ventricular contraction. This dependency of the right ventricle on the left ventricle helps to explain the right ventricular response to volume overload, pressure overload, and myocardial ischemia. The septum and its position are not the sole mechanism for ventricular interdependence. Ventricular interdependence causes overall ventricular deformation, and is probably best explained by the balance of forces at the interventricular sulcus, the material properties, and cardiac dimensions.     

Echocardiographic evaluation of patients with a left ventricular device

Limited donor heart availability is primarily responsible for the renewal of interest in mechanical left ventricular assist devices (LVADs) as a bridge to transplantation. Donor availability is unlikely to increase significantly in the near future. Experience to date has shown that many patients can be maintained long enough to undergo transplantation, and LVADs may be acceptable as alternate therapy in some who may not be candidates for transplantation. However, criteria for noninvasive evaluation of patients on LVADs have not been developed. In a prospective study using serial echocardiography, we found that aortic valve opening, aortic forward flow, nonlaminar flow in the left ventricle, and mismatch of Doppler derived cardiac output at the pulmonic valve and device output are associated with device malfunction. Echocardiography was diagnostic in five of six patients with clinical instability unrelated to the device. These findings suggest that echocardiography is helpful in the routine evaluation of patients on LVADs.     

Overcoming right ventricular failure with left ventricular assist devices

BACKGROUND: Right ventricular failure can lead to circulatory collapse while on left ventricular assist device support. By shunting blood from the femoral vein to the left ventricular assist device, cardiac output can be increased, but arterial oxygen saturation will decrease. METHODS: To determine the effects on O2 delivery, a model was developed on the basis of O2 uptake in the lungs and whole body O2 consumption. An equation was derived that related cardiac output, pulmonary venous O2 saturation, O2 consumption, and the ratio of shunt-to-systemic blood flow to systemic O2 delivery. RESULTS: When total cardiac output increases, the shunt will increase systemic O2 delivery while decreasing arterial O2 saturation and leaving systemic venous O2 saturation unaltered. When total output does not increase, the shunt will decrease systemic O2 delivery, arterial O2 saturation, and systemic venous O2 saturation. CONCLUSIONS: The analysis suggests that measuring systemic venous oxygen saturation may be a useful way to monitor patient safety. A decrease in systemic venous O2 saturation when creating the shunt implies an inadequate increase in cardiac output.     

Arrhythmogenic right ventricular cardiomyopathy associated with multiple right atrial thrombi

The authors report the case of an arrhythmogen right ventricular cardiomyopathy. The disease is characterised by the partial or total loss and the fibro-fatty replacement of right ventricular musculature and by the higher familiar incidence. The clinical importance of the disease is the malignant ventricular arrhythmia generated in the right ventricular wall, that is often fatal. Right heart failure is less frequent and develops mainly preterminally. The curiosity of this case is right atrial and ventricular thrombi diagnostized concomitantly with progressive heart failure. This combination is a rarity in medical literature, in contrast with the disease itself, as it was previously supposed. Early diagnosis, pharmacological and non-pharmacological treatment can reduce the fatal outcome.     

Reversible left atrial dysfunction possibly due to afterload mismatch in patients with left ventricular dysfunction

OBJECTIVE: The aim of this study was to define the clinical-therapeutical approach to endometrial cancer now being followed in some of the most important centers of reference for gynecological cancer in North America by means of a questionnaire. STUDY DESIGN: The questionnaire focused on four principal areas: (1) surgical staging and therapy; (2) adjuvant treatment; (3) treatment modifications; and (4) management of advanced stages (FIGO III-IV). RESULTS: There were 48 evaluable responses (77%) received by the end of December 1994 which were considered for this analysis. Lymphadenectomy is utilized routinely in 26/48 centers (54.2%) and in selective clinical-pathological conditions in another 21/48 centers (43.5%). In the majority of centers (31/48; 64.6%) radical surgery is utilized for selected indications such as cervical involvement. Only 3/48 (6.2%) centers consider the vaginal approach totally inappropriate. The great majority (40/48; 83.3%) of the centers considered postsurgical adjuvant therapy to be necessary in FIGO Stage Ic. Brachytherapy is routinely performed in 3 centers (6.2%) in postsurgical management of Stage I endometrial cancer, while the majority of the centers (31/48; 64.6%) perform brachytherapy of the vaginal vault in certain clinical-pathological conditions. A wide variety of treatments are used for advanced stages (FIGO III-IV). CONCLUSIONS: It emerges that some controversial aspects exist on endometrial cancer treatment, and these conflicting data need a large-scale multicenter randomized clinical trial.     

Evaluation of left atrial contribution to left ventricular filling in aortic stenosis by velocity-encoded cine MRI

Velocity-encoded cine MRI (VEC-MRI) can measure volume flow at specified site in the heart. This study used VEC-MRI to measure flow across the mitral valve to compare the contribution of atrial systole to left atrial filling in normal subjects and patients with left ventricular hypertrophy. The study population consisted of 12 normal subjects (mean age 34.5 years) and nine patients with various degrees of left ventricular hypertrophy resulting from aortic stenosis (mean age 70 years). VEC-MRI was performed in double-oblique planes through the heart to measure both the mitral inflow velocity pattern (E/A ratio) and the volumetric flow across the mitral valve. The left atrial contribution to left ventricular filling (AC%) was calculated. The results were compared with Doppler echocardiographic parameters. The VEC-MRI-derived mitral E/A ratios showed a significant linear correlation with E/A ratios calculated from Doppler echocardiography (r = 0.94), and the VEC-MRI-derived E/A ratios (2.1 +/- 0.5 vs 1.0 +/- 0.4) and AC% values (24.9 +/- 7.2 vs 45.7 +/- 16.4) were significantly different between normal subjects and patients with aortic stenosis (p < 0.01 in both groups). The same differences were seen in the Doppler echocardiographic parameters. The VEC-MRI-derived E/A ratio and AC% showed significant hyperbolic and linear correlations with left ventricular mass indexes (r = 0.95 and 0.86). In addition, the VEC-MRI-determined E/A ratio and the volumetric AC% displayed a highly significant hyperbolic correlation (r = 0.95). Thus VEC-MRI can be used to evaluate left ventricular diastolic filling characteristics in normal subjects and patients with abnormalities of diastolic filling.     

Acquired left ventricular to right atrial intracardiac shunt after myocardial infarction: a case report and review of the literature

A patient without a history of heart disease was seen in our institution after 3-week history of progressive weakness, dyspnea, and orthopnea. Transthoracic echocardiography demonstrated inferoposterobasal akinesis and a left ventricular to right atrial shunt through the coronary sinus, which was confirmed on cardiac catheterization. This is only the second case reported in the English-language literature documenting this rare shunt after a myocardial infarction.     

Reversibility of changes in left and right ventricular geometry and hemodynamics in pulmonary hypertension. Echocardiographic characteristics before and after pulmonary thromboendarterectomy

Pulmonary thromboendarterectomy (PTE) leads to an acute decrease of right ventricular (RV) afterload in patients with chronic thromboembolic pulmonary hypertension. We investigated the changes in right and left ventricular (LV) geometry and hemodynamics by means of transthoracic echocardiography. The prospective study was performed in 14 patients (8 female, 6 male; age 55 +/- 20 years) before and 18 +/- 12 days after PTE. Total pulmonary vascular resistance and systolic pulmonary artery pressure were significantly decreased (PVR: preoperative 986 +/- 318, postoperative 323 +/- 280 dyn x s/cm5, p < 0.05; PAP preoperative 71 +/- 40, postoperative 41 +/- 40 mm Hg + right atrial pressure, p < 0.05). End diastolic and end systolic RV area decreased from 33 +/- 12 to 23 +/- 8 cm2, respectively, from 26 +/- 10 to 16 +/- 6 cm2, p < 0.05. There was an increase in systolic RV fractional area change from 20 +/- 12 to 30 +/- 16%, p < 0.05. RV systolic pressure rise remained unchanged (516 +/- 166 vs. 556 +/- 128 mm Hg/sec). LV ejection fraction remained within normal ranges (64 +/- 16 vs. 62 +/- 12%). Echocardiographically determined cardiac index increased from 2.8 +/- 0.74 to 4.1 +/- 1.74 l/min/m2. A decrease in LV excentricity indices (end diastolic: 1.9 +/- 1 vs. 1.1 +/- 0.3, end systolic: 1.7 +/- 0.6 vs. 1.1 +/- 0.4, p < 0.05) proved a normalization of preoperatively altered septum motion. LV diastolic filling returned to normal limits: (E/A ratio: 0.62 +/- 0.34 vs. 1.3 +/- 0.8; p < 0.05); Peak E velocity: 0.51 +/- 0.34 vs. 0.88 +/- 0.28 m/sec, p < 0.05; Peak A velocity: 0.81 +/- 0.36 vs. 0.72 +/- 0.42 m/sec, ns; E deceleration velocity: 299 +/- 328 vs. 582 +/- 294 cm/sec2, p < 0.05; Isovolumic relaxation time: 134 +/- 40 vs. 83 +/- 38 m/sec, p < 0.05). We could show a marked decrease in RV afterload shortly after PTE with a profound recovery of right ventricular systolic function--even in case of severe pulmonary hypertension. A decrease in paradoxic motion of the interventricular septum and normalization of LV diastolic filling pattern resulted in a significant increase of cardiac index.