Overnight studies in severe chronic left heart failure: arrhythmias and oxygen desaturation.

Abstract

Overnight studies were performed in 10 patients with severe chronic left heart failure (New York Heart Association grades III and IV) without pulmonary disease and in eight controls. Transcutaneous oxygen (Po2) and carbon dioxide tensions (Pco2) and oxygen saturation were measured and the electrocardiogram was recorded. During sleep mean oxygen saturation fell to 92-7% (minimum 86-1%) from 95-1% when awake. During the night oxygen saturation was below 95% for 62% of the time, below 90% for 6% of the time, and below 85% for 1% of the time. In four patients there were oxygen desaturation dips (a fall of > 4% in oxygen saturation from a stable baseline that lasted > 30 s) with concurrent increases in Pco2. Two patients had bradycardia during the dips: in one there was non-sustained ventricular tachycardia during the dips and in the other there was ST depression (> 0-1 mV at 80 ms after the J point) during a dip. In the controls the fall in mean oxygen saturation from 9514% when they were awake to 9414% when they were asleep was less than the fall in patients with heart failure and there were no desaturation dips or arrhythmias.Thus patients with severe heart failure had episodes of oxygen desaturation during sleep, some of which were associated with arrhythmia. Such episodes may be related to the increased risk of sudden death in chronic heart failure.

Oscillatory Breathing Patterns During Wakefulness in Patients With Chronic Heart Failure

“…The association between CSR at night, episodes of O 2 desaturation, and arrhythmogenesis in CHF has been documented. 3 Because sleep studies were not routinely performed, we do not know how many patients also exhibited classic CSR with episodes of hypoxemia at night and whether this was a cause of the higher incidence of nonsustained ventricular tachycardia. However, in the present study, compared with PB, a CSR-like pattern was not associated with any further increase in the complexity and severity of ventricular arrhythmias, suggesting that the occurrence of cyclical breathing pattern (either genuine PB or CSR-like) may be a marker of an increased risk of ventricular tachycardia.…”

“…1 The episodes of apnea with concomitant hypoxemia and arousal, which are characteristic features of CSR, may be associated with increased sympathetic activity and precipitate ventricular arrhythmias. 2,3 A similar pattern of respiration during the daytime has been recently related to a poor outcome. 4 Patients with compensated CHF also demonstrate an oscillatory breathing pattern characterized by cyclical rises and falls in ventilation without true periods of apnea (periodic breathing [PB]).…”

Effect of oscillatory breathing on the variability of the RR Intervals and its prognostic importance in individuals with left ventricular global systolic dysfunction

“…These facts, especially those related to the development of arrhythmias and the deterioration of ventricular function could have as pathophysiological bases the autonomic imbalance, hypoxia, hypercapnia, and the increase in the sympathetic amines, therefore aggravating neurohormonal disorders, especially in regard to the elevated levels of catecholamines 10,24 . In regard to the clinical, laboratory, and evolutional findings of the individuals studied, the breathing patterns and the characteristics of V-RR were independent of functional class, the cause of left ventricular global systolic dysfunction, and the magnitude of the changes in the echocardiographic parameters.…”

“…In approximately 50% of the individuals with left ventricular global systolic dysfunction, the presence of abnormal patterns of breathing can be identified. In these individuals, oscillatory patterns of breathing (oscillatory breathing) can be observed both during sleep and during wakefulness, and are characterized by successive periods of tachy/hyperpnea followed by brady/hypopnea, and, eventually, apnea [2][3][4][5][6][7][8][9][10] . Of the types of oscillatory breathing of clinical significance, Cheyne-Stokes respiration and periodic breathing stand out.…”

Sleep-Related Breathing Disorders and Cardiac Arrhythmia

“…The possible relationship between nocturnal oxygen desaturation and arrhythmias and sudden death in heart failure patients was suggested 20 years ago (Davies et al, 1991). More recently, Gami et al (2005) reported that sudden cardiac death in almost half of 78 heart failure patients with OSA occurred during sleeping hours from midnight to 6:00 a.m., significantly deviating from the typical time of death during early morning waking hours (6:00 a.m. to noon).…”