STUDIES ON MYOCARDIAL METABOLISM OF PATIENTS WITH HYPERTENSION AND WITH CORONARY SCLEROSIS IN RESTIONG STATE, AND EFFECTS OF ANTIHYPERTENSIVE AGENTS ON MYOCARDIAL METABOLISM OF HYPERTENSIVES

Abstract

Myocardial metabolism was studied on 39 patients with hypertension and 14 patients with coronary sclerosis by means of the coronary sinus catheterization. These patients were classified into the following three groups, according to the values of blood pressure and ECG findings.Group I: 13 cases. The average value of mean blood perssure measured 127mmHg, and enlargement of left ventricle was observed in all the patients except for 2 cases.Group II: 26 cases. Hypertensives that denote depressed ST, flat or inverted T wave, or the combination of these abnormalities on ECG. The average value of mean blood pressure measured 133mmHg in height. All patients except for 2 cases showed the enlargement of left ventricle, including 4 cases with marked enlargement.Group III: 14 cases. Coronary sclerosis without hypertension. Mean blood pressure averaged 93mmHg. Enlargement of left ventricle was noticed in 6 cases.Following results thus obtained were compared with the normal data previously reported.1) In group I, myocardial O2 extraction and O2 extraction coefficient were normal, while myocardial lactate and pyruvate extraction coefficient ratios were decreased. These results indicate the disturbance of myocardial carbohydrate metabolism in this group.2) In group II, abnormalities of myocardial gaseous and carbohydrate metabolism were remarkable; i.e., O2 extraction coefficient was increased, myocardial RQ was below normal, and in a few cases O2 partial pressure of coronary venous blood was decreased. Moreover, myocardial lactate and pyruvate extraction coeffecient ratios were reduced s gnificantly, and myocardial O2 extraction ratio as well. In addition, coronary venous blood pH was measured on 12 of the patients examined and four of these showed increased coronary venous difference of pH.3) In group III, O2 extraction and O2 extraction coefficient of cardiac muscle inclined to diminish, and marked reduction of O2 partial pressure of coronary venous blood was noticed in all 4 cases. Abno malities of myocardial lactate and pyruvate metabolism were also observed in this group.4) From the data above mentioned, it is inferred that myocardial hypoxia is the major cause of these metabolic disturbances, and that, in group I, contributing factor of the hypoxia was myocardial hypertrophy, and that in group III, it is the relative limitation of coronary blood flow due to coronary sclerosis. Accordingly, group II, influenced by these two facters, exhibited the most severe changes, and the myocardial metabolism got worse, parellel with the clinical grades of hypertension and ECG findings. In some cases of group III whose ECG were normal in resting state, the increase of myocardial O2 extraction coefficient was noticed. This suggests the existence of myocardial hypoxia in these cases.5) Hexamethonium (C6) and hydralazine (HY) were administered intravenously on ten hypertensive patients. HY decreased myocardial O2 extraction coefficient in all four cases, but C6 did in only two cases out of six examined. As to myocardial lactate and pyruvate extraction coefficient ratios, C6 increased them. Some discussion concerning the different actions of these two agents on coroanry circulation were attempted.