Acute haemodynamic effects of nifedipine at rest and during maximal exercise in patients with chronic cor pulmonale

L-type Ca(2+) channels, resting [Ca(2+)](i), and ET-1-induced responses in chronically hypoxic pulmonary myocytes

In the lung, chronic hypoxia (CH) causes pulmonary arterial smooth muscle cell (PASMC) depolarization, elevated endothelin-1 (ET-1), and vasoconstriction. We determined whether, during CH, depolarization-driven activation of L-type Ca(2+) channels contributes to 1) maintenance of resting intracellular Ca(2+) concentration ([Ca(2+)](i)), 2) increased [Ca(2+)](i) in response to ET-1 (10(-8) M), and 3) ET-1-induced contraction. Using indo 1 microfluorescence, we determined that resting [Ca(2+)](i) in PASMCs from intrapulmonary arteries of rats exposed to 10% O(2) for 21 days was 293.9 +/- 25.2 nM (vs. 153.6 +/- 28.7 nM in normoxia). Resting [Ca(2+)](i) was decreased after extracellular Ca(2+) removal but not with nifedipine (10(-6) M), an L-type Ca(2+) channel antagonist. After CH, the ET-1-induced increase in [Ca(2+)](i) was reduced and was abolished after extracellular Ca(2+) removal or nifedipine. Removal of extracellular Ca(2+) reduced ET-1-induced tension; however, nifedipine had only a slight effect. These data indicate that maintenance of resting [Ca(2+)](i) in PASMCs from chronically hypoxic rats does not require activation of L-type Ca(2+) channels and suggest that ET-1-induced contraction occurs by a mechanism primarily independent of changes in [Ca(2+)](i).

Cor Pulmonale

The goals of treatment of cor pulmonale are 1) to reduce pulmonary arterial hypertension; 2) to optimize gas-exchange efficiency; and 3) to improve survival. These goals are achieved through long-term oxygen therapy, bronchodilator and vasodilator therapy, aggressive treatment of pulmonary infection, and anticoagulation. Selected patients may benefit from available surgical options.

Echocardiographic Detection of Occult Cor Pulmonale During Exercise in Patients with Chronic Obstructive Pulmonary Disease

We tested the ability of cycle ergometer exercise echocardiography to detect cases of occult cor pulmonale among 25 patients with chronic obstructive pulmonary disease (COPD). The M-mode echocardiographic ventricular septal motion, left ventricular shape determined by short-axis two-dimensional (2-D) echocardiography, and right and left ventricular pressure curves were recorded at rest and during exercise and were compared between patients. The ventricular septal motion was normal at rest in all of the patients. In nine patients (dip group), there was marked downward ventricular septal motion in early diastole during exercise, indicating distortion of the left ventricular shape. There were no distinct changes in the remaining 16 patients (non-dip group). At rest, the cardiac index was significantly lower, and right ventricular systolic and mean pulmonary artery pressures were significantly higher in the dip group than in the non-dip group. However, no significant difference was noted in the right ventricular end-diastolic pressure between the two groups at rest. The right ventricular systolic and end-diastolic pressures were greater during exercise in the dip group than in the non-dip group. In all of the patients in the dip group, the right ventricular pressure exceeded the left ventricular pressure only in early diastole, coinciding with the early diastolic dip of the ventricular septum, during exercise. In conclusion, occult cor pulmonale can be diagnosed accurately by the appearance of an early diastolic dip of the ventricular septum and distorted left ventricular shape during exercise in patients with COPD.

Effect of nifedipine on physiologic shunting and oxygenation in chronic obstructive pulmonary disease

PURPOSE

To assess changes in physiologic shunting and oxygenation following short-term treatment with nifedipine in patients with pulmonary hypertension secondary to chronic obstructive pulmonary disease.

PATIENTS AND METHODS

Changes in pulmonary vascular pressure, pulmonary vascular resistance, venous admixture, and systemic arterial oxygen tension following sublingual administration of 20 mg of nifedipine were studied in 18 patients (13 men, 5 women; mean age of 59.7 [SD 7.2] years) using Swan-Ganz catheterization. These patients had a mean peak expiratory flow rate of 112 (SD 27) L/min (mean 22.2 [SD 12.2]% of predicted value), mean forced expiratory volume in 1 second (FEV1) of 0.84 (SD 0.23) L (mean 31.2 [SD 8.5]% of predicted value), mean FEV1/forced vital capacity ratio of 31.6 (SD 4.5), and mean carbon monoxide diffusing capacity of 6.8 (SD 1.96) mmol/min/kPa.

RESULTS

There was a significant decrease in mean pulmonary vascular resistance (562 to 371 dyne sec.cm-5) and a significant reduction in the mean pulmonary arterial pressure (mean 32.8 to 23.6 mm Hg). Pulmonary venous admixture, however, increased significantly from the baseline mean of 44.6% (SD 16.1) to a mean of 56% (SD 15.6), and the mean arterial oxygen tension decreased from 5.8 (SD 1.3) kPa to 4.5 (SD 0.8) kPa at 60 minutes following drug administration (p < 0.001).

CONCLUSION

The role of nifedipine in the treatment of pulmonary hypertension secondary to chronic bronchitis may be limited because of its deleterious effect on venous admixture.

Short- and long-term hemodynamic effects of oral nifedipine in patients with pulmonary hypertension secondary to COPD and lung fibrosis. Deleterious effects in patients with restrictive disease

STUDY OBJECTIVE

The present study was undertaken to evaluate at rest the short- and long-term effects of oral nifedipine (N) in patients with pulmonary hypertension (PH).

DESIGN AND SETTING

A prospective study with ten consecutive cases during two years in a setting of a district acute hospital.

PATIENTS OR PARTICIPANTS

Seven patients with advanced COPD and three with severe lung fibrosis (LF) during a period of stable condition. Three patients with COPD were eligible for the long-term investigation.

INTERVENTIONS

Right heart catheterization with a 7F Swan-Ganz triple-lumen thermodilution catheter and radial cannulation with a 3F arterial catheter.

MEASUREMENTS AND RESULTS

Measurement of CO, MAP, RAP, PAP, PWP, HR, and ABG and calculation of CI, TSR, PAR, and DO2 before and after 20 mg of N sublingually at rest. For the group as a whole, N induced a reduction in MAP and TSR, with a significant increase in CI and DO2. There were no significant changes in PAP, PAR (magnitude of the reduction: -10 percent), HR, and PaO2. The individual analysis of the driving pressures (PAP-PWP) in function of the cardiac output demonstrated that a real vasodilating effect in the pulmonary circulation occurred in only three COPD patients (magnitude of the PAR reduction: -43 percent), while in the three patients with LF, N induced a deleterious increase in PAP and PAR. After long-term treatment (10 mg of N daily every 4 h; average 12 months) in the former, despite a persistent beneficial hemodynamic effect (magnitude of the PAR reduction: -36 percent), there was the usually expected clinical worsening.

CONCLUSIONS

N in small doses may be able in some patients with severe COPD to induce a beneficial short- and long-term hemodynamic effect on the pulmonary circulation when PH is present. On the other hand, N should not be used in patients with PH and advanced LF.

Right ventricular function at rest and during exercise in chronic obstructive pulmonary disease

Right ventricular ejection fraction (RVEF), a measure of systolic pump performance of the right ventricle, is frequently depressed at rest or during exercise in patients with chronic obstructive pulmonary disease (COPD). The most common cause of reduced RVEF in COPD is augmentation of right ventricular afterload, namely an increase in pulmonary artery pressure and pulmonary vascular resistance. Therapy with agents that decrease the afterload on the right ventricle have the potential to improve the systolic performance of this chamber. Oxygen, vasodilators such as hydralazine and nifedipine, theophylline, and sympathomimetics all may augment RVEF in part by reducing pulmonary vascular resistance and, in some cases, pulmonary artery pressures in patients with COPD and cor pulmonale. However, only oxygen therapy has been shown to improve survival.

The effect of the calcium antagonist, isradipine, on working capacity, pulmonary function, morbidity and survival rate in patients with severe chronic obstructive pulmonary disease (COPD): a randomized, double-blind, placebo-controlled study

Beneficial effects of calcium antagonists on the pulmonary haemodynamics of patients with chronic obstructive pulmonary disease (COPD) have been observed in several studies. Such effects include a decrease in pulmonary vascular resistance, an increase in cardiac output, and an increase in oxygen delivery. The clinical implications of these effects are uncertain. The randomized, double-blind, placebo-controlled, long-term study described here is the first to investigate the clinical effects of a calcium antagonist on patients with COPD. The aim was to test the hypothesis that the calcium antagonist, isradipine, could increase working capacity and lung function, and decrease morbidity and mortality. Fifty-two patients with COPD were investigated. During a 22-month observation period no statistically significant differences between the isradipine group and the placebo group were found with regard to these parameters. It is concluded that the existing evidence does not justify the introduction of calcium antagonists as part of the routine treatment of COPD.

Cardiovascular-pulmonary interaction in chronic obstructive pulmonary disease with special reference to the pathogenesis and management of cor pulmonale

Chronic obstructive pulmonary disease (COPD), which here refers to a group of diseases that have in common the physiologic defect of airway obstruction, is often associated with severe hemodynamic consequences. This article provides an overview of cardiovascular function in COPD with emphasis on recent advances in detecting, quantifying, and treating pulmonary hypertension and its major cardiac complication, cor pulmonale.

Hypoxic pulmonary vasoconstriction and gas exchange during exercise in chronic obstructive pulmonary disease

In patients with chronic obstructive pulmonary disease (COPD) studied at rest, nifedipine releases hypoxic pulmonary vasoconstriction (HPV) and worsens gas exchange. During exercise, this drug lowers pulmonary hypertension, but the effects of this lower pulmonary vascular tone on ventilation-perfusion (VA/Q) relationships are still poorly understood. To analyze them, we determined the VA/Q distributions in eight patients with stable COPD (FEV1, 36 percent of predicted) at rest and during exercise (60 percent VO2 max), before and after nifedipine (20 mg sublingually). Nifedipine shifted to the right the pulmonary pressure-flow relationship (p less than 0.01) and increased the dispersion of the blood flow distribution at rest and during exercise (p less than 0.005). These observations strongly suggest that nifedipine released HPV under both conditions. However, even after releasing HPV by nifedipine, exercise distributed blood flow more homogeneously than at rest (p less than 0.05). Besides, exercise greatly decreased the overall degree of VA/Q mismatching (p less than 0.001) not only before but also after nifedipine. Thus, we postulate that most of the VA/Q improvement that exercise may induce in patients with COPD, as it is shown here, is due to improvement in the ventilation distribution. Interestingly, this VA/Q improvement was not paralleled by a significant decrease of P(A-a)O2. This apparent paradox could be explained by 20 percent of the actual P(A-a)O2 during exercise due to diffusion limitation, as assessed through the inert gas approach. Taken all together, these results help to better understand the mechanisms that govern pulmonary gas exchange during exercise in COPD.

Acute effects of oxygen, nifedipine, and diltiazem in patients with cystic fibrosis and mild pulmonary hypertension

The acute effects of oxygen, nifedipine, and diltiazem were studied in eight patients with cystic fibrosis and mild pulmonary hypertension, to assess the possibility of relieving the latter before the occurrence of irreversible vascular changes. Oxygen decreased pulmonary pressure (-23%) and resistance (-21%), while increasing systemic resistance (+23%). Nifedipine increased cardiac index (+30%), at the expense of augmented right ventricular work (+42%), resulting in a decreased calculated pulmonary resistance (-23%); pulmonary artery pressure remained unchanged, however. Nifedipine decreased arterial Po2 (-10%), suggesting ventilation-perfusion mismatch. Four of the eight patients responded to diltiazem. Their pulmonary pressure (-35%) and resistance (-43%) decreased, while systemic vascular tone remained unchanged. Oxygen in three patients, and diltiazem in two, returned pulmonary pressures and resistances to normal values. Early reversal of pulmonary hypertension is possible, and intervention is desirable before the establishment of chronic hypoxia, cor pulmonale, or right ventricular failure. Our data does not support the use of nifedipine in pulmonary hypertension, but shows that oxygen, and in some cases diltiazem, act as effective and selective pulmonary vasodilators.

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is equated with chronic bronchitis and emphysema as one disease entity. In COPD airflow limitation is relatively persistent--unlike asthma. Tests for "small-airways disease" form no part of routine practice, for their accuracy in detecting pathological change is debatable. The proteolytic theory of the pathogenesis of emphysema highlights the role of neutrophil elastase, antielastases, oxidants, antioxidants, and thus of potential new treatments. Clinical features of COPD include breathlessness, cough, and sputum, with airflow obstruction and lung hyperinflation. The differential diagnosis includes bronchiectasis, cystic fibrosis, and pulmonary hypertension, but pulmonary fibrosis, etc., is distinguished by radiological infiltrates. Plain chest radiography cannot reliably diagnose emphysema in life, but a new method measuring lung density from the computed tomographic (CT) scan allows location, quantitation, and diagnosis of emphysema (defined by enlargement of distal air spaces) in humans in life. "Pink puffers" with breathlessness, hyperinflation, mild hypoxemia, and a low PCO2 are contrasted with "blue bloaters" with hypoxemia, secondary polycythemia, CO2 retention, and pulmonary hypertension and cor pulmonale. Antismoking measures are a major aim in management. A bronchodilator regimen combining a slow-release oral theophylline with an inhaled beta 2-agonist, ipratropium, and high-dose inhaled steroids is proposed because even modest improvement in obstruction can help these patients. In acute exacerbations with purulent sputum, antimicrobials against Streptococcus pneumoniae and Hemophilus influenzae are used with controlled oxygen therapy aiming to keep the arterial PO2 over 50 mm Hg without the pH falling below 7.25. Influenza prophylaxis is recommended, but pneumococcal vaccination remains debatable. Chronic under-nutrition in "emphysema" implies controlled trials of feeding regimens--but these remain to be assessed. Long-term oxygen therapy is the only treatment known to prolong life in blue bloaters, and oxygen concentrators and transtracheal oxygen delivery are discussed. Pulmonary vasodilators (e.g., beta 2-agonists, hydralazine, nifedipine, angiotensin-converting enzyme [ACE] inhibitors, etc.) have not yet been proved to provide long-term reduction in pulmonary arterial pressure. Blue bloaters have severe nocturnal hypoxemia in rapid eye movement (REM) sleep that is corrected by oxygen or the investigational drug almitrine.(ABSTRACT TRUNCATED AT 400 WORDS)