A Case Report of Double Aortic Arch, Vascular Ring Associated with Tracheal Stenosis / 日本心臓血管外科学会雑誌

We report a case of vascular ring with tracheal stenosis, which might be related to a prolonged endotracheal intubation. A symptomatic 2-month-old boy was admitted to our institution after prolonged intubation without a definite diagnosis. His symptoms were stridor and dyspnea, but not dysphagia. Echocardiography detected a vascular ring and this was confirmed by computed tomography and magnetic resonance imaging (MRI) (Edwards IA type). The left anterior aortic arch was divided distal to the left subclavian artery through left thoracotomy and the ligamentum arteriosus was not identified. On postoperative day (POD) 2, endotracheal extubation was unsuccessfully attempted. Further examination such as MRI and bronchoscopy revealed intimal hyperplasia of the trachea with mild compression of the trachea from the outside. We performed aortopexy and division of the small long ductus which might not be a mechanism of the tracheal compression through right thoracotomy in the second operation with successful extubation on POD 3. The patient has been discharged from the hospital and followed up at the outpatient clinic without any symptom. Tracheomalacia was a common associated anomaly in vascular ring. However, other mechanisms such as inflammatory reaction associated with prolonged intubation should be considered and be avoided in the pediatric population.

Re-do Cases and Histidine Buffered Cardioplegia / 日本心臓血管外科学会雑誌

Re-do open cardiac surgery may sometimes require complete ablation around the pericardium for the 2 major reasons of attaining better myocardial protection and obtaining effective DC cardioversion. However, this ablation may increase postoperative hemorrhage which may require blood transfusion. Hypothermia is based on the concept of myocardial protection during open heart surgery by suppressing myocardial metabolism, but recently the approach has been changed to maintaining myocardial metabolism with aerobic or anaerobic energy production. We have already reported that histidine-buffered cardioplegia which promote anaerobic glycolysis, provided an excellent functional recovery of myocardium post-ischemia with lower inotropic requirements in a range from 10°C to 37°C of myocardial temperature. Based on our theoretical background and clinical data, we tested the efficacy of this type of cardioplegia in patients receiving multiple surgical procedures with minimum ablation after sternotomy. First case, who had undergone a Bentall procedure for annulo-aortic ectasia 14 years previously had a thrombotic valve and mitral regurgitation. Aortic valve plasty and mitral valve replacement (MVR) was performed. The second case who had undergone MVR 15 years previously had malfunction of the prosthetic valve and underwent re-MVR. The third and fourth cases had ventricular septal defect (VSD) which were closed using Teflon patches. The third case had patch closure during second operation for residual shunt. The fourth case received tricuspid valve replacement (TVR) for tricuspid regurgitation due to a pacemaker lead implanted into the right ventricle through the left subclavian vein. The fifth case received coronary artery bypass surgery in a second operation for restenosis of the graft and progressing atherosclerosis. All hearts started beating spontaneously without DC cardioversion after the aortic unclamp. Ventricular fibrillation occurred in the first case while the patient was weaned from cardiopulmonary bypass and treatment was performed by aortic cross clamp, infusion of the cardioplegia followed by aortic unclamp to start own beat again. Two of 3 patients who were able to donate their own blood preoperatively did not require homologous blood transfusion. Due to advantages such as excellent myocardial protection under hypothermic or normothermic condition, ease of use and relatively lower potassium concentration, histidine-buffered cardioplegia can be an excellent candidate for myocardial protection in re-do cases with less ablation technique.

Relationship between Arterial Keton Body Ratio(AKBR) and Hepatic Blood Flow after Extracorporeal Circulation / 日本心臓血管外科学会雑誌

Recently, arterial keton body ratio (AKBR) has attracted attention as a new indicator of liver function which is in equibilium with the ratio between oxidized and reduced forms of free nicotinamide-adenine dinucleotides (free NAD⁺/NADH ration) in the mitochondria. There are few reports on whether AKBR contributes to the hepatic energy charge in the open heart surgery with extra corporeal circulation (ECC) or not. This study was undertaken to clarify the contribution of AKBR to the hepatic energy charge during ECC and the relationship between AKBR and hepatic blood flow. AKBR was determined before, during and after ECC in the open heart surgery for 14 patients. Furthermore, the blood flow in hepatic artery, portal vein and liver microcirculation was measured before, during and after ECC in canine models. Finally, the pulsatile perfusion was performed in canine models and compared with the conventional non-pulsatile perfusion for the blood flow and AKBR. In clinical cases, AKBR was decreased in all cases during the ECC. AKBR which was measured at 2 or 3hr after weaning from the ECC was negatively correlated to the total perfusion time with -0.57 as the correlation coefficient. Six patients who were on the ECC over 180min did not show a good recovery of the AKBR after weaning from the ECC. Especially, three patients presented a clinical picture of acute hepatic failure with jaundice, elevation of the serum levels of transaminase and direct hyperbililubinemia, but only one showed hypoglycemia. These patients showed no improvement in clinical data and AKBR. The patient with improved AKBR recovered clinically. In our experiment, the blood flow in the hepatic artery, portal vein was measured by electromagnetic blood flow meter and the liver microcirculation was measured by laserdoppler flowmeter. The blood flow was decreased remakably in the non-pulsatile group at all sites of measurement: it recovered after ECC in hepatic artery and portal vein, but liver microcirculation did not improve well. AKBR was decreased during ECC and did not recover after ECC in the non-pulsatile perfusion. When the pulsatile perfusion was performed, liver circulation was maintained well, and AKBR recovered well after ECC. The above results suggest that AKBR reflects the liver microcirculation and pulsatile perfusion is beneficial to the liver microcirculation. Pulsatile circulation, however, involves several problems, hemolysis, the decrease of platelets, and so on, but these problems have been improved gradually. We think that the pulsatile perfusion will be used in clinical operations to maintain the good hepatic circulation.