Shinji Murakawa

Another approach for aortic valve replacement through left thoracotomy

We report a 54-year-old man with a history of esophagectomy and retrosternal esophagogastric anastomosis for esophageal cancer through right thoracotomy in whom cardiac failure developed due to aortic regurgitation. He underwent aortic valve replacement through a left thoracotomy with division of two great arteries and their strong traction toward the surgeon by stay sutures. He has been well for 3 years postoperatively in New York Heart Association class I.

A skeletal muscle actuator for an artificial heart.

The authors developed a system to use skeletal muscle as an artificial heart actuator. This system consists of a flexible rod, sheath, crank, and cam to transmit the muscle power to a pusher plate pump and actuate it. The latissimus dorsi muscle was dissected at the lower ribs, and its end was connected with the flexible rod. The contraction of skeletal muscle was linearly transmitted, with the rod introduced inside the sheath, to the pump. The whole system was implanted in dogs (14-18 kg) and pump performance was evaluated with a mock circulatory system (preload = 10 mmHg, afterload = 75 mmHg). In these experiments, the pump output was maintained at 0.8 to 2.0 L/min (60 bpm) for 200 min, with a non-preconditioned muscle that was stimulated continuously. The output obtained was 2.5 mW/gram. Efficiency of this system was about 50% of the muscle power available. When the muscle was stimulated intermittently every 30 min, pump flow was maintained at > 0.8 L/min for 20 hr. Advantages of this system are: 1) the muscle power was linearly transmitted effectively, 2) this system could be installed with minimal surgery and without interruption in blood flow to the muscle, 3) the muscle is free from high intraventricular pressure that caused ischemia and, 4) the muscle can be set to the proper length in diastole to potentiate strong contractions.

Direct recognition of rat MHC antigens on rat antigen-presenting cells by mouse CD4+ and CD8+ T cells and establishment of T cell clones exhibiting a direct recognition pathway

Alloantigens are recognized by T cells either through a direct pathway, which involves recognition of alloantigens expressed on allogeneic antigen-presenting cells (APC), or through an indirect pathway, which involves recognition of processed alloantigens presented by self APC. We investigated whether rat xenoantigens are also recognized by direct (xenogeneic APC-restricted) and/or indirect (self APC-restricted) pathways. C57BL/6 (B6) mouse anti-F344 or WKAH rat mixed lymphocyte reactions (MLRs) were partially inhibited by addition of either anti-mouse CD4 or CD8 monoclonal antibody (mAb) and almost completely blocked in the presence of both mAbs. These xenogeneic MLRs were almost completely inhibited by simultaneous depletion of both self and xeno APCs and only partially suppressed by the elimination of either type of APC, indicating that freshly prepared splenic mouse T cells can recognize rat xenoantigens through both direct and indirect pathways. Anti-F334 T cell lines were generated from B6 anti-F344 MLR cultures, and four CD4+ and four CD8+ T cell clones were isolated from these parental lines. The parental lines and those derived T cell clones were tested for their ability to proliferate depending on the presence of F344 APC. Proliferation of CD8 clones by stimulation with F344 APC was inhibited by the addition of anti-rat class I MHC mAb but not of anti-class II MHC mAbs. Conversely, proliferation of CD4 clones was reduced by addition of anti-class II MHC mAbs. Thus, these results indicate that xeno (rat)-reactive mouse T cells recognize xenoantigens via both indirect (self APC-restricted) and direct (xeno APC-restricted) pathways and that both CD4 and CD8 subsets of T cells participate in a direct pathway of xenoantigen recognition.

Hepatoma with Growth in Right Atrium: Report of Successful Resection

A case of hepatocellular carcinoma (HCC) with growth in the right atrium is presented. Simultaneous removal of the left lobe of the liver and the intracardiac tumor was carried out using cardiopulmonary bypass. Although HCC was combined with liver cirrhosis, the patient tolerated left hemihepatectomy. The patient is doing well without signs of recurrence 7 months after operation.

Effects of Wrapping Tightness on Acute Cardiac Function in Dynamic Cardiomyoplasty

BACKGROUND It has not been clarified how tightly the heart should be wrapped for maximal augmentation of cardiac function in cardiomyoplasty. METHODS Hearts in acute failure induced by propranolol were wrapped with the left latissimus dorsi muscle, loosely (loose CMP), moderately (moderate CMP), and tightly (tight CMP) in each of 5 pigs. To measure the pressure between the latissimus dorsi muscle and the left ventricle (LV), a Millar pressure catheter with a latex balloon was placed on the anterior wall of the LV. Left ventricular wall tension was calculated according to Laplaces law, using the difference between the LV pressure and the balloon pressure. RESULTS In the loose CMP, moderate CMP, and tight CMP groups, the mean balloon pressures during unassisted beats were 8.2, 10.4, and 13.2 mm Hg, respectively. During unassisted beats, the mean LV wall tension values were 38,683, 29,938 (p < 0.05 versus loose CMP), and 26,652 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 76.8, 73.8, and 65 (p < 0.05 versus loose CMP) mm Hg, respectively, and the stroke volumes were 12.8, 9.2, and 8.5 (p < 0.05 versus loose CMP) mL, respectively. During assisted beats, the mean LV wall tension values were 20,059, 11,290, and 7,893 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 94.1, 98.1, and 92.0 mm Hg, respectively, and the stroke volumes were 13.8, 11.6, and 9.4 (p < 0.05 versus loose CMP) mL, respectively. CONCLUSIONS During unassisted beats, tight CMP (13 mm Hg) had the advantage of diminishing LV wall tension, but the disadvantage of diminishing LV pressure and stroke volume, compared with loose CMP (8 mm Hg). Moderate CMP (10 mm Hg), however, had the advantage of diminishing LV wall tension without a decrease in LV pressure and stroke volume.

Pleuroperitoneal shunting for intractable cardiogenic pleural effusions.

A 72-year-old man underwent post-infarction ventricular septal defect repair. Postoperatively, he required prolonged ventilation and could not be weaned from positive-pressure-assisted ventilation because of intractable bilateral pleural effusions. Conservative therapy was ineffective. After instituting pleuroperitoneal shunting, the patient could be weaned easily from a respirator.

Hybrid myocardial revascularization complicated by delayed anastomotic bleeding

We present a case of hybrid coronary revascularization complicated by delayed bleeding from an anastomotic site. Anastomosis of the left internal mammary artery to the left anterior descending coronary artery was successfully performed via a lateral anterior small thoracotomy. Scheduled subsequent percutaneous coronary intervention of residual stenoses was successfully performed 13 days after the surgery, but cardiac tamponade due to anastomotic site dehiscence was disclosed soon after the percutaneous procedure. We discuss the causation of the delayed bleeding that occurred after the hybrid coronary revascularization.

Reoperation for diffuse supravalvular aortic stenosis with Williams syndrome —Extended patch aortoplasty and extra-anatomic bypass from the ascending aorta to the descending aorta in a median sternotomy—

A case of diffuse supravalvular aortic stenosis (SVAS) with Williams syndrome is reported. In this case of severe diffuse SVAS, we performed the diamond-patch aortoplasty in a child. However he has been suffering from residual SVAS. At 9-years old, the myocardial injury was noted by myocardial scintigraphy. Preoperative cardiac catheterization and angiography revealed the hypoplastic ascending aorta and arch with a pressure gradient of 89 mmHg at the distal site from the left subclavian artery. Through only a median stenotomy, an extended patch aortoplasty between the valsalva sinus and distal arch was performed and an extraanatomic bypass from the ascending aorta to the descending aorta was employed using a 10 mm tube graft. We realize this technique is available because this method can relieve the left ventriculus of the pressure load and operate via only median sternotomy.

Monitoring and regulating latissimus dorsi muscle performance for circulatory assist

The purposes of this study were monitoring and regulating latissimus dorsi muscle (LDM) performance with muscle internal pressure and thickness, and with burst stimulation parameters, respectively. The unconditioned LDM flap of a pig was connected to a measurement system to examine force and contraction length. Internal pressure was measured using a catheter pressure transducer with a fluid-filled balloon inserted into the muscle, and correlated linearly with force during both contraction and relaxation. During contraction, thickness change correlated linearly with contraction length and the area enclosed within an internal pressure-thickness curve, and the X-axis was correlated linearly with muscle work. Stroke work increased incrementally according to the pulse width up to 6.72 msec or burst rate up to 120 Hz, and then plateaued at 240 Hz. The authors conclude that muscle work during contraction could be monitored with internal pressure and thickness, and that stroke work could be regulated with pulse width or burst rate.