Total Pulmonary Resistance Index Research Articles

The effect of nifedipine on monocrotaline-induced pulmonary hypertension in rats.

Effective drug therapy for pulmonary hypertension has not yet been developed. This study was designed to estimate the long-term hemodynamic and histopathological effects of nifedipine on severe pulmonary hypertension using animal models. Injection of one dose of monocrotaline produced subacute pulmonary hypertension in 7 week old Sprague-Dawley rats. Nifedipine (10 mg/kg) was administered intraperitoneally every day. For 5 weeks, bodyweight and hemodynamic parameters were measured, and right ventricle (RV) and left ventricle with septum (LV + S) were weighed separately. Medial thickness of the small pulmonary arterial wall was calculated by Suwa's method. Compared with the control group, the increase in right ventricular systolic pressure, total pulmonary resistance index, weight ratio of RV/(LV + S and medial hypertrophy in the nifedipine-treated rats were significantly limited without causing systemic hypotension. These results suggest that treatment with nifedipine may also be effective in attenuation of pulmonary hypertension when applied to humans.

Contribution of live heartworms harboring in pulmonary arteries to pulmonary hypertension in dogs with dirofilariasis.

To investigate whether adult heartworms harboring in the pulmonary arteries contribute to pulmonary hypertension, we determined the cardio-pulmonary values immediately before and after removal of heartworms from the pulmonary arteries and before and after insertion of live worms in their place. In 10 heartworm-infected dogs, 8 to 46 worms were removed. The mean pulmonary arterial pressure fell significantly from 24.5 +/- 7.9 mmHg to 16.3 +/- 4.9 mmHg (p less than 0.01) immediately after removal. The right cardiac output decreased in 7 of the 10 cases. The total pulmonary resistance and right ventricular stroke work index also decreased. At 24 hours after removal, live heartworms were put back into the pulmonary arteries of their host dog. The mean pulmonary arterial pressure elevated significantly (p less than 0.01) immediately after insertion. The right cardiac output further decreased in 7 of the 10 dogs, and the total pulmonary resistance and right ventricular stroke work index increased. Separate from this, 12 to 42 heartworms were transplanted into the pulmonary arteries of 5 heartworm-free dogs. Immediately after transplantation, the pulmonary arterial pressure did not show any significant change. However, the stroke volume decreased, and the total pulmonary resistance increased. These facts suggest a contribution of live heartworms to the pulmonary hypertension, although there is a complicated interaction among the presence of heartworms, the pulmonary lesions and the pulmonary hypertension.

Right ventricular ejection fraction from equilibrium krypton-81m blood pool scans: a noninvasive predictor of pulmonary arterial hypertension.

Based on the relation between the impedance to right ventricular ejection and ejection fraction of the right ventricle (RVEF) we tested the hypothesis that radionuclide RVEF correlates inversely with pulmonary artery pressure and allows the noninvasive prediction of pulmonary hypertension. A recently developed improved equilibrium right ventricular blood pool imaging technique using ultrashort-lived krypton-81m and simultaneous right heart catheterization were combined for assessment of right ventricular systolic performance in relation to right ventricular loading in a heterogeneous group of cardiopulmonary disorders. The study group included 9 patients with pulmonary artery hypertension secondary to left ventricular dysfunction, 5 with primary pulmonary hypertension, 5 with corrected tetralogy of Fallot, and 10 normal subjects. Linear regression analysis between radionuclide RVEF and simultaneously recorded hemodynamic measurements of right ventricular loading revealed a significant inverse correlation with mean PA pressure (r = -0.87; P less than 0.001), with total pulmonary resistance index (r = -0.81; P less than 0.001) and with pulmonary vascular resistance index (r = -0.78, P less than 0.01). The sensitivity and specificity of a resting RVEF less than 40% to indicate pulmonary hypertension (mean PA pressure greater than 20 mmHg) were 71% and 100%, respectively; positive and negative predictive values were 100% and 80%, respectively. Thus, radionuclide RVEF as a parameter of right ventricular systolic performance is predominantly dependent on right ventricular afterload and has the potential for the noninvasive prediction of pulmonary hypertension in a heterogeneous group of cardiopulmonary disorders.

Pulmonary circulation in low cardiac output syndrome following open heart surgery.

The pulmonary circulation of 41 patients with low cardiac output syndrome (LOS) in the recovery period following open heart surgery was studied. Cardiac indices (CI) of these patients in LOS was 1.64 +/- 0.28 (Mean +/- SD) L/min X m2 and increased to 2.60 +/- 0.50 L/min X m2 after the stabilization of hemodynamic conditions. Mean pulmonary arterial pressure, pulmonary arteriolar resistance index (PARI) and total pulmonary resistance index (TPRI) in the condition of LOS were very high and significantly decreased after recovery from LOS, although the mean left atrial pressure showed no significant change. The correlation coefficient (r) between CI and PARI was found to be -0.574. High Pao2 with reductions of alveolar-arterial oxygen tension difference (A-aDo2) and physiological pulmonary shunt ratio (Qs/Qt) in LOS significantly decreased concomitant with significant increases in both A-aDo2 and Qs/Qt after the stabilization of the hemodynamic condition. Moderate correlations were obtained between CI and Pao2 (r = -0.478), and high correlations were established between CI and physiological pulmonary shunt flow (Qps) (r = 0.747). These studies showed that pulmonary vasoconstriction was playing a major role in the elevation of pulmonary vascular resistance in LOS, which eventually leads to the reduction of intrapulmonary shunting.

Late results after surgical closure of ventricular septal defect in children.

Twenty-two children, who were operated on for ventricular septal defects (VSD) at 3-11 years of age, were studied 2-11 years postoperatively with respect to signs of residual shunt, cardiomegaly, physical capacity and pulmonary resistance at various rates of perfusion. There was evidence of residual shunt in one of the patients at follow-up. This was also the only patient who had persisting cardiomegaly in the group. Exercise tests were as a rule within normal limits. Total pulmonary resistance (TPR) decreased in all instances and was abnormally elevated in 6 patients at the follow-up. as compared to 12 at the pre-operative study. Total pulmonary resistance index (TRP1) was abnormally elevated in 8 patients, as compared to 10 at the pre-operative study. Whereas TPR decreased from an average pre-operative level of 7.9 to 4.2, TPR1 average remained virtually unchanged. The two most hyper-resistive patients were found to have identically high resistance indices at the follow-up investigation, indicating litt...

Relation of "Pulmonary P" to Pulmonary Circulatory Disturbances, Especially to Pulmonary Hypertension, in Patients with Chronic Pulmonary Disease

So-called pulmonary P has been described, and discussed by many investigators, but as to criteria of pulmonary P, there are still some different opinions. The purpose of this study was to investigate the relationship between the magnitude of the P waves and the disturbances of the pulmonary hemodynamics, especially pulmonary hypertension, in patients with chronic pulmonary diseases. Material and Method : Ninety patients with chronic pulmonary disease (62 cases with pulmonary emphysema, 12 with bronchial asthma, 3 with silicosis, 3 with bronchiectasis, 2 with pulmonary tuberculosis, 2 with lung tumor, 2 with pulmonary fibrosis, one with primary pulmonary hypertension, one with pyothorax, one with chronic bronchitis, and one with pulmonary sarcoidosis) were studied. Electrocardiograms of routine 12 leads were recorded just before the right heart catheterization. Results : The incidence of P waves with heights of above 0.2 mV in all of leads II, 111, and aVF increased with elevating pulmonary artery mean pressure (PAm). However, such P waves were observed in 12.5 per cent of cases without pulmonary hypertension. When P waves were 0.25 mV or more in lead II and above 0.2 mV in leads III and aVF, such a'. combination of P waves was more closely correlated with PAm than the other type of P waves, and was defined as "pulmonary P" in this study. It was found that 60 per cent of cases with PAm over 30 mmHg, 25 per cent of cases with PAm of from 20 to 29 mmHg, 10 per cent of cases with PAm of from 17 to 19 mmHg, and none of cases with PAm below 16 mmHg showed this pulmonary P. Among the cases who had the pulmonary P, PAm was measured in 1 5 cases, right ventricular systolic pressure (RVs) in 10, right ventricular end-diastolic pressure (RVd) in 6, right atrial mean pressure (RA) in 7, pulmo-nary vascular resistance index (PVRI) in 1 1, total pulmonary resistance index (TPRI) in 9, and the average values of these were 30.2 mmHg, 41.8 mmHg, 6.0 mmHg, 3.4 mmHg. 488.1 dynes, sec, cm<-5>/M2, and 743.0 dynes, sec, cm<-5>/M2 respectively. On the other hand, among the cases who did not have the pulmonary P, PAm was measured in 75 cases, RVs in 43, RVd in 48, RA in 33, PVRI in 46, and TPRI in 46, and the average values of these were 19.1 mmHg, 27.1 mmHg, 3.9mmHg, 2.5mmHg, 285.3 dynes, sec, cm5<ookikutsur -5M2, and 440.6 dynes, sec, cm-5/M2 respectively.