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Right coronary artery occlusion: its role in the mechanism of precordial ST segment depression
1First Department of Medicine, Osaka University School of Medicine, Japan.
Insights
Precordial ST segment depression during right coronary artery occlusion is linked to myocardial lactate metabolism changes. This study investigated the mechanism in patients undergoing coronary angioplasty.
Area of Science:
- Cardiology
- Electrophysiology
- Metabolic Research
Background:
- Precordial ST segment depression during right coronary artery occlusion is a recognized electrocardiographic phenomenon.
- The underlying mechanism, particularly concerning myocardial lactate metabolism, requires further elucidation.
Purpose of the Study:
- To investigate the mechanism of precordial ST segment depression during right coronary artery occlusion.
- To evaluate myocardial lactate metabolism and ST segment shifts during coronary angioplasty in different patient groups.
Main Methods:
- A 12-lead electrocardiogram was continuously recorded in 27 patients undergoing coronary angioplasty.
- Blood lactate levels were measured in the aorta and great cardiac vein.
- Lactate extraction ratio in the anterior wall was determined before and during balloon occlusion of coronary arteries.
Main Results:
- No significant differences in ST segment elevation (leads II, III, aVF) between patients with and without precordial ST depression during right coronary artery occlusion.
- No significant differences in ST segment depression (leads V1-V6) between patients with precordial ST depression during right coronary artery occlusion and left anterior descending artery occlusion.
- Patients with precordial ST segment depression during right coronary artery occlusion showed increased lactate extraction ratio during balloon occlusion compared to before, despite ST depression.
Conclusions:
- Myocardial lactate metabolism is altered during right coronary artery occlusion, even with precordial ST segment depression.
- The findings suggest a complex interplay between ischemia, electrophysiological changes, and metabolic alterations in the anterior wall during coronary artery occlusion.
Abstract:
To investigate the mechanism of precordial ST segment depression during right coronary artery occlusion, precordial ST segment shifts and myocardial lactate metabolism were evaluated during coronary angioplasty in 10 patients with (group A) and 7 patients without (group B) precordial ST segment depression during balloon occlusion of the right coronary artery, and in 17 patients with precordial ST segment depression during balloon occlusion of the left anterior descending artery (group C). A 12 lead electrocardiogram was continuously recorded in each patient. Blood lactate in the aorta and great cardiac vein was measured during the procedure, and the lactate extraction ratio in the anterior wall was determined both before and during balloon occlusion. Eight of the 10 patients in group A and 1 of the 7 patients in group B had a dominant large right coronary artery. There were no significant differences in summed ST segment elevation in leads II, III and a VF between group A (0.56 +/- 0.26 mV) and group B (0.46 +/- 0.19 mV) during balloon occlusion of the right coronary artery, and no significant differences in summed ST segment depression in leads V1 to V6 during balloon occlusion between group A (0.44 +/- 0.26 mV) and group C (0.38 +/- 0.14 mV). Lactate extraction ratio before balloon occlusion was similar among the three groups. Patients in group A had a higher lactate extraction ratio during (38 +/- 11%) compared with before (30 +/- 11%) (p less than 0.05) balloon occlusion despite precordial ST segment depression.(ABSTRACT TRUNCATED AT 250 WORDS)