Objects. Myocardial revascularization is performed preferentially with internal mammary artery grafts. Pedicle preparation and pharmacologic vasodilatory treatment vary greatly. Objective measurements are difficult since peripheral and later coronary vascular resistance and possible competitive flow of the native bypassed coronary artery will influence the results significantly. Our objectives were:(1) measurement of internal mammary artery graft flow with the transit-time flow technique; (2) comparison of two surgical take-down techniques (skeletonizing vs standard pedicle preparation): (3) quantitation of transit-time flow compared to the free pedicle flow and (4) the vasodilatory effect of papaverine on internal mammary artery flow.Method. Consecutive elective cases of coronary artery bypass grafting, performed by two surgeons using routinely either skeletonizing of the internal mammary artery (group A, n = 10) or classtcal pedicle preparation technique (group B, n = 10), were studied prospectively. Anesthesia, cardiopulmonary bypass and operative data were otherwise comparable; likewise, hemodynamlc parameters showed no statistical differences between the two groups. Transit-time flow (CardioMed, MediStim, Norway) was measured at the following time points: beginning (1) and end of take-down (2); after papaverlne soaking: before (3) and on cardiopulmonary bypass (4); free flow into a beaker (5); after anastomosis; on (6) and off cardiopulmonary bypass (7).

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A rapid and efficient circulatory support system may save a patient in cardiogenic shock. Left heart bypass with percutaneous and trans-septal placement of the aspiration cannula simplifies the circuit and eliminates the need for an oxygenator. In this pre-clinical study we assessed left heart bypass support with a centrifugal pump using new cannulae prepared for percutaneous placement (14 F arterial catheter and 16 F left atrial aspiration line) in 5 anaesthetized pigs. Animals were supported for two hours at a mean flow of 3.2 l/min (4,033 rpm), a mean haematocrit of 29% and low heparinisation (ACT double baseline). Hemodynamic measurements and blood samples were taken at baseline (A), 10 minutes (B), one hour (C) and 2 hours (D) on support. Results show maintenance of hemodynamic parameters throughout the 2 hour support period. Only systolic arterial and left ventricular pressure decreased by 12% and 20% respectively from baseline to the end of the support period with a 13% increase in cardiac output. When the pump was turned on (0-3 l/min) there was usually a decrease in heart rate, systolic pressure and left ventricular pressure, with unchanged cardiac output (non failing model). Potassium increased from 3.9 to 4.2 mmol/l (ns), and plasma hemoglobin from 6.0 to 18.2 mg/dl (p<0.05). Thrombocytes decreased from 187 to 155 10(9)/l (ns). In conclusion, this preclinical study demonstrated the feasibility of an efficient left heart bypass of short duration with a centrifugal pump using cannulae prepared for percutaneous placement. Left heart bypass was well tolerated hemodynamically and no significant laboratory change occurred within the two hours of support. This opens several possibilities for the short term support of patients in cardiogenic shock and eventually also for patients submitted to minimally invasive cardiac surgery.

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