Cerebral tissue oxygen saturation during percutaneous cardiopulmonary support in a canine model of respiratory failure.

Percutaneous cardiopulmonary support (PCPS) has come to be applied for cardiopulmonary resuscitation and in the management of severe respiratory failure as well as severe heart failure. We investigated cerebral tissue oxygen saturation during PCPS in a canine model of respiratory failure using near-infrared spectroscopy. Animals were mechanically ventilated with 10% oxygen to make a respiratory failure model. Perfusion with PCPS was performed via the left femoral artery and switched to that via the right axillary artery. Cerebral tissue oxygen saturation was 54.2 +/- 3.4% during PCPS via the femoral artery and was 82.3 +/- 4.6% during PCPS via the axillary artery (p = 0.001). Hepatic tissue oxygen saturation was not significantly different. LV dP/dt max increased significantly after switching to the axillary blood supply (p = 0.001). Conventional PCPS may not have the capability of supporting cerebral circulation under severe respiratory failure without organic heart disease.

Eccentric roller type total artificial heart creating interatrial shunt.

Creating an interatrial shunt to achieve left-right flow balance and modification of the blood chambers to improve the basic performance of the device were performed in developing an eccentric roller type total artificial heart (ERTAH). Smaller blood chambers reduce friction loss and increase durability and energy efficiency. We changed the left blood chamber volume of 60 ml to 40 ml and the right blood chamber volume of 53 ml to 35 ml compared with previous types. Designs of inlet and outlet ports were modified to prevent backflow. In the mock circulatory system, redesigning the blood chambers resulted in a 20% increase in energy efficiency, about a two-fold increase of cardiac output and improved durability compared to the previous type. In an animal experiment, the ERTAH operated at a driving rate of 160 rpm with a left flow rate of 6.0 L/min and a right flow rate of 5.4 L/min. Interatrial shunt flow rate was 250-400 ml/min.

Is communication to endocardium necessary for angiogenesis in transmyocardial laser revascularization?

There is evidence of angiogenesis being induced after transmyocardial laser revascularization (TMLR), although the precise mechanism has not been fully elucidated. This study was designed to examine whether or not blood flow from the left ventricle through the channels is essential for angiogenesis following TMLR. Ten dogs underwent the creation of two types of laser channels in the left ventricle: 1) a transmural channel (TMC), which penetrates the myocardium, and 2) a non-transmural channel (NTMC), which does not open to the epicardium. The animals were sacrificed on the 28th postoperative day and the vascular density was examined. Vessels with smooth muscle media were seen within or around the channel remnant. The vessel density was compared between TMC and NTMC. The outer and inner halves of the myocardium in the TMC region were compared in the same way. The density of vessels within and around the channel remnants was significantly higher in TMC than in NTMC (1.439 versus 0.685 vessels/microscopic visual field (mvf=40X); p=0.0025). The vascular density was significantly higher in the region adjacent to TMC than in a distant region (>3 mm from the channel center). The vascular density was significantly higher in the outer half than in the inner half of the myocardium (1.730 versus 1.180 vessels/mvf: p=0.0459). These findings demonstrate that communication to the left ventricular lumen enhances angiogenesis of TMLR, although blood flow in the channel did not exist 4 weeks after TMLR and angiogenesis tended to be more highly enhanced in the outer half than in the inner half of the myocardium.

Stent-grafting to descending thoracic aorta during coronary artery bypass grafting.

We report on 2 patients who underwent successful concomitant operation of coronary artery bypass grafting and stent grafting to descending thoracic aortic aneurysms. The device was inserted through a small linear incision on the anterior wall of the aortic arch. Intraoperative stent grafting to descending thoracic aortic aneurysms is an alternative therapeutic option for patients who require concomitant coronary artery bypass grafting and descending aortic replacement.

Flow balance between the left and right cardiac output of an eccentric roller type total artificial heart.

We have made an eccentric roller type total artificial heart (ERTAH). The ERTAH is a positive-displacement device comparable to a DeBakey roller pump. Its left and right outputs are determined by the size of its blood chambers, and the ratio of its left and right output is almost constant. We focused on an interatrial shunt to achieve left-right balance. We have conducted numerical simulation, a mock test, and an acute animal experiment to analyze left-right heart balance during ERTAH operation. Numerical simulation was performed under conditions in which the flow of the left artificial heart was fixed at 6 L/min, the flow of the right artificial heart was varied from 4.8 to 6 L/min, and the interatrial resistance was also varied. The relationship between the interatrial shunt flow rate and the output of the left and right artificial hearts was balanced when the flow of the right artificial heart was at 5.45 L/min. In a mock test, 2 DeBakey roller pumps were connected to the left and right sides of a Donovan mock circulatory system, and an interatrial shunt was created between the inlet ports of the left and right roller pumps. The interatrial resistance of the mock system was varied from 7.7, to 4.3, and to 2.9 mm Hg x min/L when the inner diameter of the interatrial shunt was 6, 8, and 10 mm, respectively. As in the mock test, 2 roller pumps were used to bypass the right and left hearts of a goat weighing 60 kg. The flow rate of the left heart was almost constant (4.7 L/min). The flow of the right heart was approximately 4.1 L/min when the interatrial shunt flow rate was zero. A leading consideration was that the left to left shunt through the bronchial arteries in this goat was approximately 0.6 L/min. In developing the ERTAH, we considered that creating an interatrial shunt between the inlet ports of the ERTAH as well as making a difference between the chamber volumes might be effective in balancing the left-right sides of the artificial heart.

[Simultaneous operation of emergency coronary artery bypass grafting and gastrotomy with suturing ulcer].

A 62-year-old man with complaints of severe chest pain came to our hospital. An emergency coronary angiography was performed and he was diagnosed as having acute myocardial infarction. Due to severe triple vessels disease he was referred to the department of Cardiovascular Surgery to undergo emergency coronary artery bypass grafting. In the coronary care unit, sudden hematoemesis due to hemorrhagic gastric ulcer occurred, however, just when he was going to be transferred to the operation room. Because the gastric bleeding was thought to be serious under extracorporeal circulation, which was indispensable for coronary artery bypass grafting, gastrotomy with suturing ulcer was performed prior to median sternotomy with use of intraaortic balloon pumping. Severe infection was not complicated. His postoperative course was uneventful.

[A case of left atrial thrombi following mitral valvuloplasty for mitral regurgitation associated with idiopathic thrombocytopenic purpura].

A 58-year-old man, who had been submitted to an indication of mitral valvuloplasty (MVP) because of severe mitral regurgitation, was diagnosed as idiopathic thrombocytopenic purpura (ITP). In order to diminish the peri-operative blood loss, splenectomy and high-dose bolus administration of gamma-globulin (400 mg/kg/day) were performed at the time of two weeks and during last five days respectively, prior to MVP surgery. In early post-operative stage, anticoagulant therapy was held down considering ITP, and we were not troubled with bleeding throughout the peri-operative period. On the fourteenth post-operative day, however, mural thrombi in the left atrium were pointed out by transesophageal echocardiography (TEE). Then anticoagulant therapy was reinforced by increasing the warfarin dose. When TEE was restudied on 36th, post-operative day, mural thrombi had almost disappeared. Although it is commonly known that mitral valvuloplasty has low risk of thrombosis and less necessity of anticoagulation, hyper coagulability may be feasible in the early post-operative period of our case whose ITP is meticulously treated prior to surgery. Suitable anticoagulation should have been performed regardless of ITP immediately after MVP.

[Short-term results of leaving elephant trunk in type A aortic dissection].

Elephant trunk prosthesis was devised for treatment of multiple aortic aneurysm. But it has applied to type A aortic dissection. Because residual false lumen often dilates gradually and come to have the risk of rupture. Two patients who were diagnosed as type A aortic dissection were performed total aortic arch replacement with Elephant trunk prosthesis on distal anastmosis. Postoperative diagnostic images showed that residual false lumen of proximal descending aorta were thrombosed. Now it is not necessary to perform next extensive aortic replacement. Complication which is threatened in using Elephant trunk prosthesis, paraplegia, thromboembolism, kinking of prosthesis could have been avoided by setting suitable length and diameter of the prosthesis.