DIURNAL-VARIATION IN PULMONARY-ARTERY PRESSURE

Previous observations have suggested that pulmonary artery pressure ri ses during sleep, whereas systemic artery pressure falls. A system has been developed for careful and accurate recording of pulmonary arteri al pressure, and applied it to two groups of subjects: patients with h eart failure, and patients with chronic stable angina. The results hav e largely confirmed the nocturnal pressure rise in pulmonary arterial pressure. Detailed analysis strongly suggests that the same physiologi cal mechanisms producing a fall in systemic pressure are responsible f or the rise in pulmonary pressure. The precise mechanism remains to be elucidated.