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Murine Isolated Heart Model of Myocardial Stunning Associated with Cardioplegic Arrest
Published on: August 6, 2015
Enhanced protection of myocardial function by systemic deep hypothermia during cardioplegic arrest in multiple
Insights
Deep systemic hypothermia (average 20.8 degrees C) significantly improved myocardial protection during complex coronary artery bypass grafting. This method reduced the need for postoperative catecholamine support, especially in patients with longer aortic cross-clamp times.
Area of Science:
- Cardiology
- Cardiac Surgery
- Hypothermia
Background:
- Myocardial protection during aortic cross-clamping is crucial for coronary artery bypass grafting (CABG) outcomes.
- Systemic hypothermia is a common adjunct to cardioplegia for myocardial preservation.
Purpose of the Study:
- To evaluate the effectiveness of deep systemic hypothermia (around 20°C) compared to moderate hypothermia (around 27°C) in myocardial protection during CABG.
- To assess the impact of hypothermia depth on the requirement for postoperative catecholamine support.
Main Methods:
- A prospective study of 71 patients undergoing CABG, divided into two groups based on hypothermia depth.
- Group A: Moderate hypothermia (average 26.8°C) with 1000-1200 cc cardioplegia.
- Group B: Deep hypothermia (average 20.8°C) with 100-300 cc cardioplegia.
Main Results:
- No significant differences in surgical deaths, perioperative infarcts, or neurologic damage between groups.
- Deep hypothermia (Group B) significantly reduced postoperative catecholamine dependence (5.13%) compared to moderate hypothermia (56.25%, p < 0.0001).
- This benefit was most pronounced in patients with aortic cross-clamp times exceeding 60 minutes (0% vs 91% catecholamine support, p < 0.0001).
Conclusions:
- Deep systemic hypothermia is a simple and effective method for myocardial preservation during CABG, particularly when aortic cross-clamp times exceed 60 minutes.
- Deep hypothermia significantly reduces the need for inotropic support post-surgery, indicating improved myocardial protection.
- The findings support the use of deep hypothermia in complex CABG procedures involving multiple distal anastomoses.
Abstract:
The effectiveness of deep systemic hypothermia (20 degrees C) in myocardial protection during aortic cross-clamping was elevated. Seventy-one consecutive patients undergoing coronary artery bypass grafting were divided into two groups. In group A (32 patients) systemic temperature was reduced to an average of 26.8 degrees C (range 24 degrees to 28 degrees C) and the amount of cardioplegic solution infused totalled 1,000 to 1,200 cc. In Group B (39 patients) systemic temperature was reduced to an average of 20.8 degrees C (17 degrees to 23 degrees C) and the total amount of cardioplegic solution infused was 100 to 300 cc. The mean number of coronary (distal) anastomoses per patient was 4.46 in Group A and 4.51 in Group B. There were no surgical deaths, perioperative infarcts, or neurologic damage in either group. Postoperative catecholamine dependence was used as an indicator for inadequate myocardial protection. Catecholamine support was required by 18 patients (56.25%) in Group A and two patients (5.13%) in Group B (p less than 0.0001). Patients of both groups who received five or six coronary anastomoses, whose aortic cross-clamp time was 60 minutes or more, and whose preoperative left ventricular ejection fractions were above 50% were compared: Ten of the 11 (91%) in Group A required catecholamine support as opposed to none of the 12 in Group B (p less than 0.0001). No significant difference in the incidence of catecholamine requirement was found between patients of both groups whose aortic cross-clamp time was less than 60 minutes (2/13 patients in Group A and 2/21 patients in Group B), regardless of their preoperative left ventricular ejection fraction. We conclude that when aortic cross-clamp time exceeds 60 minutes, that is, when multiple distal anastomoses are performed, deep systemic hypothermia is a simple and effective method for myocardial preservation.
