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Measurement of regional myocardial blood flow. Application of the electrolytic hydrogen clearance method in man
M Kawasuji1, F Kawajiri, T Iwa
1Department of Surgery, Kanazawa University School of Medicine, Japan.
Insights
This study shows that electrolytic hydrogen clearance effectively measures myocardial blood flow during surgery. It confirms improved blood flow after coronary bypass grafting in patients with severe blockages.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Medical Imaging
Background:
- Assessing myocardial perfusion intraoperatively is crucial for evaluating coronary bypass grafting (CABG) outcomes.
- Ischemic heart disease significantly impacts regional myocardial blood flow.
Purpose of the Study:
- To assess intraoperative myocardial perfusion.
- To evaluate the adequacy of coronary bypass grafting using a quantitative method.
- To investigate the relationship between coronary artery stenosis and myocardial blood flow.
Main Methods:
- Regional myocardial blood flow was measured using the electrolytic hydrogen clearance method in 49 patients.
- Patients were divided into non-ischemic (Group I) and ischemic (Group II) heart disease groups.
- Group II was further stratified by coronary artery stenosis severity (less than 75% vs. greater than or equal to 75%).
Main Results:
- Mean myocardial blood flow was significantly lower in patients with greater than or equal to 75% stenosis (98 +/- 9 ml/min/100 gm) compared to non-ischemic (154 +/- 7 ml/min/100 gm) and less than 75% stenosis (145 +/- 5 ml/min/100 gm) groups.
- Blood flow decreased progressively with increasing stenosis severity in the left anterior descending artery.
- Following CABG, myocardial blood flow significantly increased in grafted areas of Group IIb patients (from 99 +/- 11 to 150 +/- 7 ml/min/100 gm).
Conclusions:
- The electrolytic hydrogen clearance method provides quantitative assessment of myocardial perfusion.
- This method effectively evaluates the recovery of myocardial blood flow after coronary bypass grafting.
- It is particularly useful for assessing outcomes in patients undergoing mammary artery grafting.
Abstract:
To assess myocardial perfusion intraoperatively and to evaluate the adequacy of coronary bypass grafting, we measured regional myocardial blood flow by the electrolytic hydrogen clearance method in 49 patients. Group I comprised 10 patients with nonischemic heart disease and group II, 39 patients with ischemic heart disease undergoing coronary bypass grafting. Group II was subdivided according to the percent stenosis of the coronary arteries supplying the ventricular regions: group IIa, less than 75% stenosis; group IIb, greater than or equal to 75% stenosis. Mean myocardial blood flows were 154 +/- 7, 145 +/- 5, and 98 +/- 9 ml/min/100 gm in groups I, IIa, and IIb, respectively (p less than 0.01, group IIb versus groups I and IIa). Mean blood flows were 161 +/- 19, 159 +/- 12, 78 +/- 12, and 59 +/- 15 ml/min/100 gm in areas of the left anterior descending coronary artery with less than 50%, 75%, 90%, and 99% stenosis in group II. In areas with a totally occluded left anterior descending coronary artery with collaterals, mean flow was 90 +/- 15 ml/min/100 gm. The mean myocardial blood flows were 40 +/- 7 and 100 +/- 14 ml/min/100 gm in areas with anterior Q wave and non-Q wave infarction, respectively (p less than 0.01). After cardiopulmonary bypass, the mean flow increased from 99 +/- 11 to 150 +/- 7 ml/min/100 gm in the grafted areas in group IIb (p less than 0.01), but it did not change in group I or IIa. The electrolytic hydrogen clearance method provided quantitative evaluation of myocardial perfusion and recovery from hypoperfusion by coronary bypass grafting. This method was especially useful in patients undergoing mammary artery grafting.