Compensatory hyperkinesis of the ventricular walls in acute myocardial ischaemia.

After ligation of the anterior descending coronary artery in dogs, conductance of the left circumflex branch and contractility of the ventricular muscular areas supplied by the left descending coronary artery and its circumflex branch were studied over 60 min. After ligation a considerable increase in contractility of the myocardial areas of the posterior wall with intact blood supply was found and a further increase parallel with a considerably enhanced flow in the circumflex branch. At the same time the contractile power of the anterior ventricular myocardium with a poor blood supply greatly decreased. A close correlation was found between the increase in flow in the circumflex branch and the increase in contractility of the intact areas. The tissue catecholamine level showed a marked increase in the myocardial areas with impaired blood supply.