J. Zipfel

Unfavorable effects of ventricular pacing on myocardial energetics.

SummaryThe effects of ventricular pacing (90–330 beats/min) and atrial pacing (120–210 beats/min) on myocardial oxygen consumption

Prediction of myocardial blood flow by DPTI and prediction of the adequacy of myocardial O2 supply by the DPTI/STTI ratio under maximal coronary dilation.

(M\dot VO_2 )

Examination of the validity of the DPTI as an estimate of myocardial oxygen supply with special reference to the DPTI/TTI ratio.

and its hemodynamic determinants and on myocardial pumping efficiency were studied systematically on intact dogs. In six closed-chest experiments 158 steady states were analyzed. Myocardial blood flow was measured with a differential pressure sinus catheter, oxygen consumption (5–30 ml/min·100 g) was determined simultaneously by the Fick principle and the additive hemodynamic parameter Et. Ventricular and atrial pacing were compared with both methods at identical heart rates. Additionally, the coincidence between both methods of determining

Usefulness and limitations of myocardial oxygen consumption indices

M\dot VO_2

Physiologisches Institut, Lehrstuhl L der Universit~t GOttingen (Direktor: Prof. Dr. reed. H. J. Bretsehneider) Abteilung for experimenteHe Kardiologie (Leiter: Professor Dr. reed. G. Hellige) Unfavorable effects of ventricular pacing on myocardial energetics*)

overproportionally up to 50% in sinus rhythm with sympathetic stimulation (norepinephrine, atropine) within each experiment. Ventricular pacing increased