Development of a new selective coronary perfusion cannula

Abstract

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 2mm in diameter. Ejected flow velocity, circuit pressure, and the amount of leakage were measured at an infusion rate of 100 and 200mL/min, with the latter two parameters measured under the counterpressure of 0 and 50cmH2O to examine the influence of coronary vascular resistance. Without counterpressure, the balloon type presented with the highest flow velocity (263cm/s at 200mL/min) and perfusion pressure (64mmHg at 200mL/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 50cmH2O 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.