Cor pulmonale: correlation with central airway lesions, peripheral airway lesions, emphysema, and control of breathing.

We have analyzed the heart and lung findings in 31 patients in the National Institutes of Health (NIH) Nocturnal Oxygen Therapy Trial (NOTT) with particular emphasis on cor pulmonale. Increased right ventricular weight was related to decreased bronchiolar diameter, decreased ratio of bronchiolar diameter to external arterial diameter, and an increased proportion of airways less than 400 microns in diameter. No relationship was found between the severity of emphysema, mucous gland enlargement, peripheral airway mucous plugging, or other measurement of central and peripheral airways. Patients with right ventricles weighing more than 100 g had higher pulmonary artery pressures at rest and higher arterial CO2 levels than those weighing 100 g or less. When the patients were divided into Types A, B, and X according to Burrows' criteria, those with Type X had a higher volume proportion of mucous glands; type B were intermediate; and Type A had the smallest. The amount of bronchial muscle was less in Type B patients than in Type A, and right ventricles weighted less in Type A patients than in Type B. Hypoxic ventilatory drive was lower in Type B patients than in Type A. Absolute right ventricular weight appeared to be a better measurement of right ventricular enlargement than relative right ventricular weight in the NIH NOTT patients. We conclude that right ventricular weight in patients with hypoxic chronic airflow obstruction (CAO) is related to airway narrowing, and that the Type B syndrome is associated with decreased ventilatory drive.