Angina pectoris

Autor: Jan K. Kwoczynski, Hideo Toyoshima, Teruo Nagaya, Ali Ekmekci, Myron Prinzmetal
Rok vydání: 1961
Předmět:
Zdroj: The American Journal of Cardiology. 7:412-426
ISSN: 0002-9149
DOI: 10.1016/0002-9149(61)90485-4
Popis: 1. 1. Increase in the R wave and decrease in the S wave have been clinically observed with myocardial infarction and during episodes of the variant form of angina pectoris. 2. 2. The same changes have been reproduced in experiments with animals by acute ischemia. 3. 3. The electrocardiographic changes were most marked from the center of the ischemic area, where ischemia is most severe, and became progressively smaller as recorded toward the periphery. 4. 4. The term “giant R” wave has been used to describe this marked increase in amplitude of the R wave. 5. 5. The giant R wave has been demonstrated during severe attacks of the variant form of angina pectoris. As pain subsided, the R wave gradually returned to the preattack level. These findings are similar to those observed in experiments on animals after ligation of a large coronary artery and release of the ligation. 6. 6. Hemorrhagic hypotension following coronary occlusion resulted in increased severity of ischemia. There was an additional increase in the R wave and the S wave receded or disappeared. These changes were reversed with return to normal systemic pressure by transfusion. 7. 7. In ischemia with S-T depression due to hemorrhagic hypotension, a decrease in the R wave and an increase in the S wave sometimes occur. This is similar to findings in severe classic angina pectoris. R and S wave changes in ischemia with S-T depression are opposite to those seen in ischemia with S-T elevation. 8. 8. Injection of potassium and sodium in various concentrations directly into a coronary artery produced characteristic R and S changes under nonischemic conditions. High concentration potassium or low concentration sodium resulted in increased amplitude of R waves and decreased amplitude of S waves. Low concentration potassium or high concentration sodium resulted in reduced amplitude of R waves and increased amplitude of S waves. Five per cent glucose in water injected directly into the coronary artery produced a large increase in the amplitude of the R wave and a marked receding or disappearance of the S wave, together with the appearance of S-T depression. 9. 9. Among the explanations for these changes in the R and S waves, the possible role of the membrane action potential, of electrical conductivity of the extracellular medium and of the propagation process have been discussed. 10. 10. Increases in the R wave and decreases in the S wave are noted in severe acute ischemia and may have great clinical significance. When decrease in the R wave and increase in the S wave occur, ischemia probably is less severe in that particular part of the heart. 11. 11. Similar changes in the R and S waves can occur with electrolyte alterations without ischemia.
Databáze: OpenAIRE
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