Kiichiro Kumagai

Right ventricular myxoma obstructing the pulmonary artery during early childhood

Primary cardiac tumors are uncommon during infancy and childhood. Myxomas originating in the right ventricle are even less common in pediatric patients. A 2-year-old girl was referred to our hospital under a diagnosis of right ventricular tumor. The aim of the operation was extirpation of the tumor. Perioperative cardiac arrest occurred when the tumor obstructed the pulmonary artery. After promptly establishing cardiopulmonary bypass, the tumor was removed from the right ventricular outflow tract. The patient was discharged on the 13th postoperative day without complications.

Development of a method to construct three-dimensional finite element models of thoracic aortic aneurysms from MRI images

Most patients die when thoracic aortic aneurysms rupture. In order to avoid the ruptures, the aneurysms are replaced with aortic prostheses when their maximum diameter exceeds 5 cm. Because this criterion is based on the experiences, some aneurysms rupture even if the diameters are smaller than this criterion. To treat the aneurysm properly, it is necessary to find out the new criterion. The rupture is thought to have a close relationship with the stress in the wall. Hence, there is much research about the stress, but this research uses the straight tube model. The model shape does not seem appropriate to a thoracic aorta shape. Hence, we developed the method to construct three-dimensional finite element models of thoracic aortic aneurysms from MRI images.

Coronary artery bypass grafting in a patient with hemophilia B: continuous recombinant factor IX infusion as per the Japanese guidelines for replacement therapy

We herein report our experience of successfully managing the hemostatic system by controlling serum factor IX levels throughout the perioperative period in a patient with hemophilia B. Coronary artery bypass grafting with cardiopulmonary bypass was planned for a 52-year-old man with moderate severity of hemophilia B. During surgery, recombinant factor IX (rFIX; BeneFIX® Pfizer Japan inc., Tokyo, Japan) was administered by bolus infusion followed by continuous infusion as per the guidelines of the Japanese Society on Thrombosis and Hemostasis. The operative course was uneventful without any considerable bleeding or complications.

Continuous flow left ventricular assist device implantation concomitant with aortic arch replacement and aortic valve closure in a patient with end-stage heart failure associated with bicuspid aortic valve

Left ventricular assist device (LVAD) implantation has become an established treatment for patients with end-stage heart failure as a bridge to cardiac transplantation. During LVAD implantation, some patients require concomitant surgeries, including tricuspid valve repair, aortic valve repair or replacement, and patent foramen ovale closure. However, concomitant aortic surgeries are rare in patients requiring LVAD implantation. We successfully performed total arch replacement with an open distal technique, aortic valve closure, and continuous flow LVAD implantation simultaneously.

SmgGDS Prevents Thoracic Aortic Aneurysm Formation and Rupture by Phenotypic Preservation of Aortic Smooth Muscle Cells

Background: Thoracic aortic aneurysm (TAA) and dissection are fatal diseases that cause aortic rupture and sudden death. The small GTP-binding protein GDP dissociation stimulator (SmgGDS) is a crucial mediator of the pleiotropic effects of statins. Previous studies revealed that reduced force generation in aortic smooth muscle cells (AoSMCs) causes TAA and thoracic aortic dissection. Methods: To examine the role of SmgGDS in TAA formation, we used an angiotensin II (1000 ng·min−1·kg−1, 4 weeks)–induced TAA model. Results: We found that 33% of Apoe−/−SmgGDS+/− mice died suddenly as a result of TAA rupture, whereas there was no TAA rupture in Apoe−/− control mice. In contrast, there was no significant difference in the ratio of abdominal aortic aneurysm rupture between the 2 genotypes. We performed ultrasound imaging every week to follow up the serial changes in aortic diameters. The diameter of the ascending aorta progressively increased in Apoe−/−SmgGDS+/− mice compared with Apoe−/− mice, whereas that of the abdominal aorta remained comparable between the 2 genotypes. Histological analysis of Apoe−/−SmgGDS+/− mice showed dissections of major thoracic aorta in the early phase of angiotensin II infusion (day 3 to 5) and more severe elastin degradation compared with Apoe−/− mice. Mechanistically, Apoe−/−SmgGDS+/− mice showed significantly higher levels of oxidative stress, matrix metalloproteinases, and inflammatory cell migration in the ascending aorta compared with Apoe−/− mice. For mechanistic analyses, we primary cultured AoSMCs from the 2 genotypes. After angiotensin II (100 nmol/L) treatment for 24 hours, Apoe−/−SmgGDS+/− AoSMCs showed significantly increased matrix metalloproteinase activity and oxidative stress levels compared with Apoe−/− AoSMCs. In addition, SmgGDS deficiency increased cytokines/chemokines and growth factors in AoSMCs. Moreover, expressions of fibrillin-1 (FBN1), &agr;-smooth muscle actin (ACTA2), myosin-11 (MYH11), MYLLK, and PRKG1, which are force generation genes, were significantly reduced in Apoe−/−SmgGDS+/− AoSMCs compared with Apoe−/− AoSMCs. A similar tendency was noted in AoSMCs from patients with TAA compared with those from control subjects. Finally, local delivery of the SmgGDS gene construct reversed the dilation of the ascending aorta in Apoe−/−SmgGDS+/− mice. Conclusions: These results suggest that SmgGDS is a novel therapeutic target for the prevention and treatment of TAA.

Selective Cerebral Perfusion with the Open Proximal Technique during Descending Thoracic or Thoracoabdominal Aortic Repair: An Option of Choice to Reduce Neurologic Complications

PURPOSE Selective cerebral perfusion with the open proximal technique for thoracoabdominal aortic repair has not been conclusively validated because of its procedural complexity and unreliability. We report the clinical outcomes, particularly the cerebroneurological complications, of an open proximal procedure using selective cerebral perfusion. METHODS A retrospective chart review identified 30 patients between 2007 and 2015 who underwent aortic repair through left lateral thoracotomy with selective cerebral perfusion, established through endoluminal brachiocephalic and left carotid artery and retrograde left axillary artery. RESULTS The mean durations of the open proximal procedure and cerebral ischemia (the duration of the open proximal procedure minus the duration of selective cerebral perfusion) were 110.3 ± 40.1 min and 24.8 ± 13.0 min, respectively. There were two cases (7%) of permanent neurologic dysfunction (PND) but no in-hospital deaths. Multivariate analysis identified the duration of cerebral ischemia as an independent risk factor for neurologic complications including temporary neurologic dysfunction (TND; odds ratio (OR): 1.13; p = 0.007), but no correlation was found between selective cerebral perfusion duration and neurologic complications. CONCLUSION Despite the relatively long duration of the open proximal procedure, selective cerebral perfusion has a potential to protect against cerebral complications during thoracic aortic repair through a left lateral thoracotomy.

Successful management of antibody-mediated rejection after cardiac transplantation in a patient supported by a left ventricular assist device for more than 3 years

Due to donor shortage, patients with refractory heart failure need to be supported on mechanical circulatory support (MCS). Critically, patients undergo several deployments of MCS in stages inevitably requiring blood products transfusion. MCSs per se along with blood products can trigger immune allosensitization. Antibody-mediated rejection (AMR) is associated with significant mortality after heart transplantation. Here, we present the case with high panel-reactive antibody over 95% who developed AMR early after heart transplantation. This life-threatening complication was successfully treated with multi-modal treatment including anti-CD20 antibody, rituximab.

Modification of a Standard Thoracoabdominal Incision to Preserve Collaterals to Adamkiewicz Artery

We report a case of a 35-year-old male who underwent thoracoabdominal aortic repair of a chronic dissecting aortic aneurysm, Crawford extent II. Preoperative computed tomography showed thrombosis of almost all intercostal arteries. Precise diagnostic assessment demonstrated the Adamkiewicz artery originating from the left lateral thoracic artery and subscapular artery, which would have been at risk after using a standard Stoneys incision, thus potentially causing paraplegia or paraparesis due to spinal cord ischemia. We modified the lateral thoracic incision anteriorly and successfully preserved the collateral arteries without impairing the spinal cord function.