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Preparation of the internal thoracic artery by vasodilator drugs: is it really necessary? A randomized double-blind
1Department of Cardiothoracic Surgery, Rabin Medical Center (Beilinson Campus), Petach Tikva, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Insights
Topical vasodilators did not significantly improve left internal thoracic artery (LITA) free flow compared to placebo during coronary artery bypass grafting. This study suggests current preparation methods offer no significant advantage over saline immersion.
Area of Science:
- Cardiovascular Surgery
- Vascular Physiology
Background:
- The left internal thoracic artery (LITA) is the preferred graft for coronary artery bypass grafting (CABG).
- Preventing LITA spasm, and optimizing its diameter and flow are crucial for successful grafting.
- Various vasodilators are used topically or intraluminally to prepare the LITA.
Purpose of the Study:
- To determine the most effective vasodilator for LITA preparation in CABG patients.
- To compare the efficacy of papaverine, nitroglycerin, verapamil, and nitroprusside against placebo.
Main Methods:
- A randomized, double-blind, placebo-controlled study involving 80 patients undergoing elective CABG.
- LITA free flow was measured before and after topical application of vasodilators or placebo in a special applicator tube.
- Five treatment groups received papaverine, nitroglycerin, verapamil, nitroprusside, or normal saline.
Main Results:
- All groups showed a significant increase in LITA free flow over time.
- No statistically significant differences in patient demographics, surgical times, or arterial pressures were observed between groups.
- The second LITA flow measurement did not differ significantly among the five treatment groups (P = 0.2).
Conclusions:
- Topical vasodilator application using an applicator tube did not yield significantly superior LITA free flow compared to placebo.
- The study suggests that standard preparation methods with topical vasodilators may not offer a significant advantage over saline for LITA free flow.
Objective:
The internal thoracic artery has become the conduit of choice for coronary artery bypass grafting. To avoid spasm of the artery, and increases in its diameter and flow, various vasodilators have been used either intraluminally or by topical application by different surgeons. In order to define the best vasodilating agent for preparation of the internal thoracic artery, a randomized double-blind placebo-controlled clinical study was performed in a group of patients submitted for elective coronary artery bypass grafting.
Methods And Results:
Eighty (80) consecutive patients submitted for elective first time coronary artery bypass grafting were randomly subdivided into five treatment groups. Free flow of the left internal thoracic artery was measured using an electromagnetic flow meter. The first measurement was performed shortly after the internal thoracic artery was dissected from the chest wall and the second just prior to performing distal anastomosis to the left anterior descending coronary artery. During the time interval between the two measurements the internal thoracic artery was immersed in a special applicator tube containing 20 ml solution of one of the following drugs: papaverin 2 mg/ml, nitroglycerin 1 mg/ml, verapamil 0.5 mg/ml, nitroprusside 0.5 mg/ml, normal saline 0.9%.
Results:
No statistically significant differences were found between the groups in respect to age, body surface area, bypass time, cross clamping time, and time interval between the two flow measurements. Mean arterial pressure at the time of the first and second internal thoracic artery flow measurements did not show statistically significant differences either within or between the groups. In all five groups, the free flow of the internal thoracic artery increased significantly with time. However, no statistically significant differences were shown between the five groups with respect to second flow (P = 0.2).
Conclusions:
Within the limits of our study design, we suggest that preparation of the LITA by topical vasodilator drugs using a special applicator tube does not result in a significantly superior free flow than placebo.