The Effect of Metabolic and Respiratory Acidosis on Myocardial Functions

Abstract

The experimental study was undertaken to quantitatively evaluate the effects of acidosis on the myocardial functions by measuring left ventricular contractile force, myocardial digitalis tolerance and ventricular fibrillation threshold in 20 dogs, and the following results have been obtained.
1) A mutual co r relation is demonstrated significantly between left ventricular contractile force and arterial blood pH. However, the reduction of ventricular contractile force during metabolic acidosis is greater than that during respiratory acidosis. In regard to the relation between ventricular contractile force and base excess, there is a significant correlation during metabolic acidosis, but no correlation during respiratory acidosis.
2) The significant reduction of myocardial digitalis tolerance is demonst rated during metabolic acidosis, whereas the digitalis tolerance is maintained at almost control level during respiratory acidosis. The decreased ventricular contractile force under the metabolic or respiratory acidosis increases by the administration of acetyl strophanthidin. However, the increased contractile force by the administration of acetyl strophanthidin during respiratory acidosis is greater than that during metabolic acidosis. By the correction of acidosis, ventricular contractile force and myocardial digitalis tolerance return to control values.
3) V entricular fibrillation threshold reduces significantly during metabolic acidosis, whereas it is maintained at almost control value during respiratory acidosis. Myocardial impedances during metabolic and respiratory. acidosis are no significant difference to control value.