Late iatrogenic coronary stenosis after selective intraoperative antegrade myocardial protection for stentless aortic valve replacement

Development of a new selective coronary perfusion cannula

The two most common types of coronary perfusion cannulae currently being used are the "balloon type", with a balloon at the tip, and the "fenestrated type", which has holes along the side near the tip. However, on occasion an unusually high perfusion pressure or a considerable amount of leakage is encountered during infusion of the cardioplegic solution. We have examined the properties of a newly developed Kochi Medical School (KMS)-type cannula and compared these to the properties of the balloon-type and fenestrated-type cannulae in an ex vivo experimental model that contains ostia of 4, 3, or 2 mm in diameter. Ejected flow velocity, circuit pressure, and the amount of leakage were measured at an infusion rate of 100 and 200 mL/min, with the latter two parameters measured under the counterpressure of 0 and 50 cmH2O to examine the influence of coronary vascular resistance. Without counterpressure, the balloon type presented with the highest flow velocity (263 cm/s at 200 mL/min) and perfusion pressure (64 mmHg at 200 mL/min) but without leakage. The fenestrated type yielded a considerable amount of leakage (40 % at an ostium size of 2 mm). The KMS type showed a lower flow velocity and circuit pressure with less leakage. Under 50 cmH2O counterpressure, however, only the KMS-type cannula could inject the water to any ostium size at both flow rates. These results suggest that the concept of the KMS-type cannula may be advantageous to achieving a secure infusion to a diseased coronary ostium.