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Salvage of ischemic myocardium
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SALVAGE OF ISCHEMIC MYOCARDIUM. Puri, Pritpal S. Wayne State Univ. School of Med., Detroit, Mich. USA. In view of the relationship between infarct size and incidence of power failure, the means to salvage ischemic myocardium are of critical clinical importance. Changes in curves of contraction as measured by means of a strain gauge tipped probe were used to assess the effects of various interventions on viability of ischemic myocardium. Increase in afterload with methoxamine resulted in extension of ischemic zone; afterload reduction with nitroprusside and nitroglycerin had the opposite effect. Prolonged infusion with isoproterenol was injurious while the effects of norepinephrine and digitalis were dose dependent. Coronary reperfusion of up to 2 weeks after coronary occlusion of l-3 hrs. resulted in recovery of myocardial contractility, the extent of recovery varied with the duration of preceding occlusion - Isoproterenol given during reperfusion resulted in high incidence of fatal ventricular arrythmias and reduced the extent of myocardial recovery. Norepinephrine did not have similar effects. Propranolol and allopurinol seem to exert protective effect on reperfused myocardium. In conclusion, viability of ischemic myocardium can be modified by several interventions and its survival extended by prolonged rep.erfusion.
CORONARY REPERFUSION: EFFECT OF DRUGS. Puri, Pritpal S., Puro, H. and Williams, R. Wayne State Univ. School of Med., Detroit, Mich. USA. In dogs with 45 to 120 mins. of coronary occlusion (CO), Isoproterenol (Isop.) or norepinephrine (NE) infusion was initiated 10 mins. prior to release of CO and was continued for up to 45 mins. of reperfusion (rep.). In Isop. treated group, ventricular tachycardia (Vt) occurred during rep. in all of the animals; Vt was fatal in 50% of those with 1 hr. of CC and in 80% of those with 2 hrs. of co. Gross myocardial hemorrhages were noted. Amongst survivors, after 2 weeks of rep., myocardial contractility (mc) as measured by strain-gauge tipped probe recovered over 56-75% of reperfused myoca.rdium. In contrast, in NE ;;g;;&ddogs, Vt occurred only rarely. All of the animals . After 2 weeks of rep. mc recovered over the entire reperfused region in animals with up to 1 hr. of occlusion; over 75% of reperfused myocardium in animals with 2 hrs. 'of occlusion. In conclusion, Isop. resulted in serious and frequently fatal Vt during rep. along with development of gross myocardial hemorrhages. In NE treated animals, Vt was rare and myocardial contractility recovered over reperfused myocardium. (Supported by a grant from the Mich. Heart Assoc. and DGH Research Corp.).
SALVAGE OF ISCHEMIC MYOCARDIUM. Puri, Pritpal S. Wayne State Univ. School of Med., Detroit, Mich. USA. In view of the relationship between infarct size and incidence of power failure, the means to salvage ischemic myocardium are of critical clinical importance. Changes in curves of contraction as measured by means of a strain gauge tipped probe were used to assess the effects of various interventions on viability of ischemic myocardium. Increase in afterload with methoxamine resulted in extension of ischemic zone; afterload reduction with nitroprusside and nitroglycerin had the opposite effect. Prolonged infusion with isoproterenol was injurious while the effects of norepinephrine and digitalis were dose dependent. Coronary reperfusion of up to 2 weeks after coronary occlusion of l-3 hrs. resulted in recovery of myocardial contractility, the extent of recovery varied with the duration of preceding occlusion - Isoproterenol given during reperfusion resulted in high incidence of fatal ventricular arrythmias and reduced the extent of myocardial recovery. Norepinephrine did not have similar effects. Propranolol and allopurinol seem to exert protective effect on reperfused myocardium. In conclusion, viability of ischemic myocardium can be modified by several interventions and its survival extended by prolonged rep.erfusion.
CORONARY REPERFUSION: EFFECT OF DRUGS. Puri, Pritpal S., Puro, H. and Williams, R. Wayne State Univ. School of Med., Detroit, Mich. USA. In dogs with 45 to 120 mins. of coronary occlusion (CO), Isoproterenol (Isop.) or norepinephrine (NE) infusion was initiated 10 mins. prior to release of CO and was continued for up to 45 mins. of reperfusion (rep.). In Isop. treated group, ventricular tachycardia (Vt) occurred during rep. in all of the animals; Vt was fatal in 50% of those with 1 hr. of CC and in 80% of those with 2 hrs. of co. Gross myocardial hemorrhages were noted. Amongst survivors, after 2 weeks of rep., myocardial contractility (mc) as measured by strain-gauge tipped probe recovered over 56-75% of reperfused myoca.rdium. In contrast, in NE ;;g;;&ddogs, Vt occurred only rarely. All of the animals . After 2 weeks of rep. mc recovered over the entire reperfused region in animals with up to 1 hr. of occlusion; over 75% of reperfused myocardium in animals with 2 hrs. 'of occlusion. In conclusion, Isop. resulted in serious and frequently fatal Vt during rep. along with development of gross myocardial hemorrhages. In NE treated animals, Vt was rare and myocardial contractility recovered over reperfused myocardium. (Supported by a grant from the Mich. Heart Assoc. and DGH Research Corp.).