In 1946, Vineberg' inserted one end of an internal mammary artery into a dog myocardium. Four months later, connection between the implanted artery and the left coronary artery was demonstrated by injection of a radiopaque mass into the implant. In 1950, Vineberg performed a similar operation on a 53-year-old man with angina pectoris. Patency of that implanted vessel was demonstrated at necropsy 62 hr. after the operation.2 2 Since that operation, patency of such myocardial implants has been observed for periods as long as 10 years after internal mammary artery implantation.3 However, the determinants of patency of myocardial revascularization implants have not been adequately defined.Distal runoff of implant blood into the myocardium was postulated by Vineberg to be an important factor in maintaining implant patency.4 The absence of immediate flow from the implant into myocardium as well as the patency of myocardial implants without distal runoff has made this thesis unacceptable.5, 6 In the absence of distal runoff, patency of blind-ended myocardial implants has been found to be proportional to the length of the myocardial tunnel and the magnitude of the resultant phasic motion of blood within the implant. Maintenance of the fluidity of blood within an implant by phasic implant blood flow has been attributed to mechanical defibrination of blood by ventricular pulsatile compression of the implant.&dquo; This hypothesis was examined by noting the effect of to and fro motion of blood upon the fluidity and fibrinogen content of blood in myocardial implants without proximal or distal runoff.at UNIV NEBRASKA LIBRARIES on April 11, 2015 ang.sagepub.com Downloaded from 108 MATERIALS AND METHODS Seventeen mongrel dogs, weighing 15 to 30 kg, were anesthetized with 10 mg per kg of sodium thiamylyl. A cuffed endotracheal tube was inserted, and ventilation was maintained at a constant volume and rate by a positive pressure respirator utilizing ambient air.The entire valveless length of the external jugular vein was exposed. After all the tributaries were carefully ligated, the thoracic end of the jugular venous segment was ligated and transected. The venous segment was allowed to be distended by blood. After distention of the vessel, the cephalic end of the 8to 12-cm jugular segment was ligated and the segment was excised. The isolated venous segments without proximal or distal runoff were inserted into myocardial tunnels or attached to the pericardial pleura. Venous segments without proximal or distal runoff positioned in myocardial tunnels. In each dog, a myocardial tunnel was incised with a special knife-edged Bainbridge instrument~ in the anterior portion of the left ventricle parallel to and 2 cm from the anterior descending ramus of the left coronary artery. One half of the isolated venous segment was inserted into the incised myocardial tunnel while the remainder of the implant protruded through the pericardium ( fig. 1). This implant position permitted emptying of the tunneled portion of the isolated venous segment ...

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United States. Myocardial infarction accounted for approximately 50 per cent of these fatalities.' Extensive literature concerning attempts to revascularize the ischemic myocardium has appeared in the last decade, but determinants of myocardial implant patency have never been adequately defined. Immediate flow through arterial or venous implants has been considered an important factor in maintaining implant patency. 2, 3, 4, Other investigators doubted the existence of immediate implant blood flow and have suggested that the continual to and fro motion of blood within the implant is the important factor in maintaining the fluidity of blood within the lumen of the graft.6, & d q u o ;In these experiments, implant blood flow was measured immediately following myocardial revascularization. In addition, the role of perfusion pressure in regulating myocardial implant flow was investigated. METHODS AND MATERIALSMongrel dogs of either sex, weighing 15 to 30 kg were anesthetized with 10 mg/kg sodium thiamlyl (Surital) .~ A cuffed endotracheal tube was inserted and ventilation was maintained at a constant rate and volume by a positive pressure respirator supplying ambient air. A left thoractomy through the fifth intercostal space was performed. The pericardium was incised 2 cm anterior and parallel to the phrenic nerve. Myocardial implants were constructed with the internal mammary artery in 6 dogs and the jugular vein in 10 dogs. TECHNICAL FACTORS IN THE PREPARATION OF MYOCARDIAL IMPLANTSJugular venous implant t Through a longitudinal skin incision parallel to the sternomastoid muscle, the entire valveless length of the external jugular vein was exposed. The tributaries from the vessel were carefully ligated with 4-0 silk sutures.