LEFT-VENTRICULAR VOLUME IN PATIENTS WITH HEART-FAILURE AND CHEYNE-STOKES RESPIRATION DURING SLEEP

In patients with congestive heart failure (CHF), elevated, left ventri cular (LV) volume might lead to pulmonary congestion and hypocapnia, w hich would create a predisposition to the development of Cheyne-Stokes respiration with central sleep apnea (CSR-CSA). In addition, because LV volume affects cardiac output, it should influence the lengths of h yperpneas. We therefore evaluated LV volumes and transcutaneous PCO2 ( PtcCO(2)) during wakefulness and stage 2 sleep in 16 patients with CHF due to nonischemic dilated cardiomyopathy (NIDC). Data were then comp ared between those with (n = 7) and those without CSR-CSA (n = 9). LV end-diastolic volume (LVEDV) was significantly higher in patients with than those without CSR-CSA (585 +/- 118 versus 312 +/- 41 ml, p < 0.0 5). Compared with patients without CSR-CSA, those with CSR-CSA had low er mean stage 2 sleep PtcCO(2) (36.3 +/- 2.2 versus 41.2 +/- 1.2 mm Hg , p < 0.05) and a lesser change in PtcCO(2) from wakefulness to stage 2 sleep (-0.4 +/- 0.3 versus 2.0 +/- 0.4 mm Hg, p < 0.001). Among pati ents with CSR-CSA, hyperpnea length was inversely related to LVEDV (R = 0.769, p = 0.043) owing to the direct relationship of cardiac output to LVEDV (R = 0.791, p = 0.034). We conclude that CSR-CSA in patients with CHF due to NIDC is associated with increased LV volumes possibly through the direct or indirect influence of LV volume on Pa-CO2 and c ardiac output.