Table 1.
Summary of in vivo experimental studies investigating the infarct-limiting effect of myocardial cooling during ischaemia, i.e. with cooling initiated before ischaemia or at least 5 min before the end of coronary artery occlusion
| Species | Ref. | Cooling procedure | Duration of CAO (min)/CAR (h) | Target heart temperature (°C) | Time of coolinga | IS with Cooling vs. Control groups (% decrease) |
|---|---|---|---|---|---|---|
| Rabbit | 36 | Topical epicardial cooling | 30/3 | ∼33 | 10 min CAO → 15 min CAR | 23 ± 4 vs. 44 ± 4 (−48%) |
| Rabbit | 22 | Topical epicardial cooling | 120/3 | ∼30 | 30 min CAO → 15 min CAR | 59 ± 3 vs. 72 ± 3 (−18%) |
| Rabbit | 49 | Closed pericardioperfusion circuit | 30/3 | ∼34 | −30 → 25 min CAO | 18 ± 3 vs. 35 ± 6 (−49%) |
| Rabbit | 24 | Topical epicardial cooling | 30/3 | ∼32 | 20 min CAO → 120 min CAR | 27 ± 4 vs. 51 ± 5 (−47%) |
| Rabbit | 12 | Blood cooling through heat exchanger | 30/3 | ∼35 | 0 → 30 min CAO | 11 ± 3 vs. 37 ± 3 (−70%) |
| 10 → 30 min CAO | 18 ± 3 vs. 37 ± 3 (−51%) | |||||
| 20 → 30 min CAO | 34 ± 2 vs. 37 ± 3 (NS) | |||||
| ∼32 | 0 → 30 min CAO | 4 ± 1 vs. 37 ± 3 (−89%) | ||||
| 10 → 30 min CAO | 8 ± 1 vs. 37 ± 3 (−78%) | |||||
| 20 → 30 min CAO | 23 ± 2 vs. 37 ± 3 (−38%) | |||||
| Rabbit | 25 | Total liquid ventilation | 30/3 | ∼32 | 0 → 30 min CAO | 4 ± 1 vs. 38 ± 1 (−89%) |
| Rabbit | 48 | Total liquid ventilation | 30/72 | ∼32 | 5 → 30 min CAO | 4 ± 1 vs. 39 ± 2 (−90%) |
| 15 → 30 min CAO | 11 ± 5 vs. 39 ± 2 (−72%) | |||||
| Rabbit | 37 | Surface cooling (water blankets) | 30/3 | ∼37.0 | Before CAO→ 180 min CAR | 30 ± 5 vs. 59 ± 1 (−48%) |
| 0 min CAO → 180 min CAR | 33 ± 5 vs. 59 ± 1 (−43%) | |||||
| 15 min CAO→ 180 minCAR | 42 ± 1 vs. 59 ± 1 (−28%) | |||||
| Rabbit | 52 | Topical epicardial cooling | 30/3 | ∼35 | −20 min before CAO → 15 min CAR | 16 ± 3 vs. 46 ± 4 (−65%) |
| Rabbit | 44 | Surface cooling | 60/4 | ∼32 | 5 → 60 min CAO | 78 ± 10 vs. 82 ± 7 (NS) |
| Total liquid ventilation | 5 → 60 min CAO | 45 ± 18 vs. 82 ± 7 (−45%) | ||||
| 20 → 60 min CAO | 58 ± 5 vs. 82 ± 7 (−29%) | |||||
| Pig | 26 | Endovascular cooling | 60/3 | ∼34 | 20 min CAO → 15 min CAR | 9 ± 6 vs. 45 ± 8 (−80%) |
| Pig | 27 | Topical epicardial cooling | 40/3 | ∼29 | 0 → 40 min CAO | 25 ± 2 vs. 62 ± 5 (−60%) |
| Pig | 28 | Intracoronary cold saline infusion | 60/3 | ∼33 | 15 min CAO → 15 min CAR | 9 ± 2 vs. 36 ± 4 (−75%) |
| Pig | 35 | I.V. cold saline + endovascular cooling | 40/∼4.3 | ∼33 | 25 min CAO → 25 min CAR | 46 ± 8 vs. 75 ± 5 (−39%) |
| Sheep | 30 | Surface cooling (ice bags) | 60/3 | ∼38.5 | 0 min CA0 → 180 min CAR Control Group at 39.5°C | 63 ± 2 vs. 72 ± 3 (−12%) |
| ∼37.5 | 49 ± 1 vs. 72 ± 3 (−31%) | |||||
| ∼36.5 | 39 ± 1 vs. 72 ± 3 (−46%) | |||||
| ∼35.5 | 22 ± 2 vs. 72 ± 3 (−70%) | |||||
| Dog | 32 | Hypothermic retroperfusion of autologous blood | 210/3 | ∼28–30 | 30 → 210 min CAO | 6 ± 3 vs. 24 ± 7b (−75%) |
CAO, coronary artery occlusion; CAR, coronary artery reperfusion; IS, infarct size (expressed as % of area at risk); Ref, reference number.
aThe time of the application of the cooling strategy and not the actual time at which the target temperature was reached. In several studies, a delay was inevitable between the onset of the cooling protocol and the time of achievement of the target temperature (e.g. with low rate cooling strategy such as surface cooling).
bThe Control value corresponds to infarct sizes observed with normothermic retroperfusion.