A randomised comparison of intermittent aortic cross clamping and warm blood cardioplegia for elective coronary surgery
Jonathan Hyde, John Isaac, Robert Cramb, Timothy Graham and Bruce Keogh
Queen Elizabeth Hospital, Edgbaston, Birmingham, United Kingdom B15 2TH
Intermittent aortic cross clamping with ventricular fibrillation (XCF) used by 40% of UK surgeons for coronary surgery (CABG). Whereas this technique relies on electrically induced ventricular fibrillation followed by anoxia to achieve myocardial standstill, intermittent antegrade warm blood cardioplegia (IAWBC) employs hyperkalaemia to induce diastolic arrest. To determine whether rapidly induced arrest provides additional myocardial protection we randomised patients undergoing elective CABG to three myocardial protection strategies: Group 1 received XCF. Group 2 received IAWBC with all anastomoses constructed under a single cross clamp (SXC). Group 3 received cardioplegia after each distal anastamosis but proximal anastomoses were performed after removal of the cross clamp (SCT).
Demographic details and the number of grafts were the same in all groups. The area under the time-activity curve (AUC) was calculated for Troponin I and creatine kinase using 12 timepoints up to 48h. There was a <10% variance between duplicate samples. Results are expressed as mean (SD):
|
|
'P' |
XCF |
SXC |
SCT |
|
n |
- |
16 |
16 |
15 |
|
Age |
- |
63.2 (7.5) |
61.2 (6.3) |
56.9 (9.4) |
|
Clamp time (mins) |
a , b |
25.7 (7.0) |
49.7 (14.0) |
41.6 (12.9) |
|
Bypass time (mins) |
- |
65.2 (18) |
65.7 (19) |
69.9 (22.0) |
|
AUC Troponin I |
a , b |
29,580 (30052) |
12,297 (11598) |
6,648 (3143) |
|
AUC CK-MB |
b |
35,859 (25932) |
27,269 (15101) |
17,148 (6356) |
|
Inotropes |
c |
4 |
0 |
0 |
a XCF v SXC p<0.05 (Kruskal-Wallis with Dunn's post test)
b XCF v SCT p<0.05 (Kruskal-Wallis with Dunn's post test)
c XCF v IAWBC p<0.05 (Fisher's Exact test)
This study demonstrates that intermittent antegrade warm blood cardioplegia strategies offer significantly better myocardial protection than intermittent aortic cross clampling for elective coronary artery bypass surgery.
