Differential effects of sleep stage on coronary hemodynamic function during stenosis

We have demonstrated in a previous study that in the normal heart REM sleep induces surges in heart rate and coronary blood flow which are abolished by bilateral stellectomy. To study the effects of sleep in the stenosed coronary circulation, dogs were instrumented with Doppler flow probes and hydraulic occluders around the left circumflex coronary artery to measure coronary blood flow and to produce a 60% flow reduction. Catheters were placed in the aorta to measure mean arterial blood pressure. Electrodes were implanted via the frontal sinus to identify sleep stages. In the absence of stenosis, mean blood pressure was 95 +/- 3 mmHg, HR was 111 +/- 4 bpm, and coronary blood flow was 33 +/- 2 ml/min. During stenosis, REM induced episodic increases in heart rate which were accompanied by 38% decreases in coronary blood flow. We conclude that in the stenosed coronary circulation, REM sleep produces episodic sinus tachycardia and coronary blood flow reduction.