Takashi Minowa

Optimal blood flow for cooled brain at 20°C

Abstract Background . Optimal conditions for deep hypothermic perfusion and protective brain blood flow remain unclear. Methods . Dogs (n = 52) underwent 120 minutes of cardiopulmonary bypass at 20°C with perfusion flow rates of 2.5, 5, 10, 20, 40, and 100 mL · kg −1 · min −1 . We examined the effect of the various flow rates and different perfusion pressures on brain blood flow, metabolism, and intracellular pH. Results . The brain was ischemic and acidotic when the perfusion flow rate was less than 5 mL · kg −1 · min −1 and pressure was less than 10 mm Hg. When perfusion pressure was higher than 10 mm Hg, cerebral cortex blood flow was more than 9 mL · 100 g −1 · min −1 and intracellular pH, higher than 6.95. The cerebral metabolic rate for oxygen decreased at a flow rate of 2.5 mL · kg −1 · min −1 . The cerebral metabolic ratio of glucose to oxygen and the cerebral vascular resistance were lowest when perfusion pressure was 10 to 30 mm Hg. Full-flow (100 mL · kg −1 · min −1 ) perfusion caused paradoxical brain acidosis; a flow of 40 mL · kg −1 · min −1 provided the best results. Conclusions . Both extremely low-flow perfusion and excessive perfusion cause brain acidosis. Low-flow perfusion at a pressure of 20 mm Hg provides cerebral vasorelaxation and aerobic metabolism during operations at 20°C.

Minimized mortality and neurological complications in surgery for chronic arch aneurysm: axillary artery cannulation, selective cerebral perfusion, and replacement of the ascending and total arch aorta.

Abstract  Objective: Cerebral complication is still a major concern in surgery for arteriosclerotic aortic arch disease. For preventing this complication, axillary artery cannulation, selective cerebral perfusion, and replacement of the ascending and arch aorta were applied to thoracic aortic aneurysm involving aortic arch. Method: From May 1999 to July 2002, consecutive 39 patients with true aneurysm (29 patients) or chronic aortic dissection (10 patients) involving aortic arch underwent replacement of the ascending and arch aorta with an elephant trunk under hypothermic cardiopulmonary bypass through the axillary artery cannulation and selective cerebral perfusion. The brain was continuously perfused without any intermission through the axillary artery. Concomitant operation included coronary artery bypass grafting (CABG) in two patients, aortic valve replacement (AVR) in one, Bentall operation in two, mitral valve replacement (MVR) in one, and aortic valve sparing operation in one. Patient age at operation was 40–84 (72 + 9) years and 24 of them were older than 70 years of age. Results: There was one operative death (2.5%) due to bleeding from the left lung, and one hospital death due to respiratory failure. Postoperative permanent neurological dysfunction was found in one patient (2.5%). Two patients presented temporary neurological dysfunction (5%). Thirty‐six of the 39 patients were discharged from hospital on foot. Conclusion: Continuous perfusion through the axillary artery with selective cerebral perfusion and replacement of the ascending and arch aorta may minimize cerebral complication leading to satisfactory results in patients with chronic aortic aneurysm involving aortic arch.

Spontaneous splenic rupture after mitral valve replacement for infective endocarditis

We report a successful treatment of massive bleeding due to spontaneous splenic rupture after mitral valve replacement. A 61-year-old man was admitted to our hospital for intermittent high fever. An echocardiogram demonstrated a large vegetation on the posterior cusp of the mitral valve and mitral regurgitation of moderate degree. Staphylococcus epidermidis was cultured from his arterial blood. He underwent a mitral valve replacement after 3 weeks of antimicrobiological therapy with penicillin G crystalline and minocycline hydrochloeide. The patient fell into hemorrhagic shock on postoperative day 11 after complaining dull pain on his left upper abdomen for 3 days. A computed tomography demonstrated a splenic rupture and massive hematoma in the retroperitoneum. A splenic arterial embolization was done before splenectomy. The blood and clot of 2800 g were sucked from peritoneal and retroperitoneal cavities. There were no mycotic aneurysms nor abscess but the torn capsule on the swelled and partially necrotic spleen. The patient discharged uneventfully on postoperative day 43. Infective endocarditis frequently causes splenic infarction but rarely splenic rupture. Anticoagulation therapy after mitral valve replacement might have emphasized the bleeding in the patient.

Retrograde cerebral perfusion: experimental approach to brain oedema.

Retrograde cerebral perfusion is used during aortic surgery as an adjunct to profoundly hypothermic circulatory arrest.1–3 Although it may protect the brain and extend the safe period of circulatory arrest, brain oedema is a possible side-effect. However, whether retrograde cerebral perfusion causes brain oedema or not has not been shown. Also, it is not known what causes brain oedema after retrograde cerebral perfusion, if it does: brain ischaemia, intracranial hypertension, or both during retrograde cerebral perfusion? To investigate these questions, we designed the present study, using a developed experimental model with simultaneous sagittal sinus and superior vena caval perfusion.4

Use of ultrasonically activated scalpel for the paced patient —A case report—

A paced patient underwent mitral valve replacement for mitral stenosis using ultrasonically activated scalpel. There were minimum bleeding and no homologous blood transfusion was required. Ultrasonically activated scalpel fid not interfere the pulse generator nor the transesophageal echocardiography. Ultrasonically activated scalpel is useful for the open heart surgery in paced patients.

Concomitant aortic arch and root replacement using a stentless xenograft for acute type a dissection

A 78-year-old woman with an aortic root aneurysm and aortic regurgitation developing acute type A dissection successfully underwent aortic root replacement using a stentless xenograft during core cooling, followed by total aortic arch replacement under selective cerebral perfusion with deep hypothermia. This bioprosthesis can be used in the same way as a free-hand homograft and potentially provides an aggressive, safe option for acute aortic dissection requiring aortic root reconstruction in elderly patients.

Endovascular Stent-Grafting in a Patient with Concomitant Descending Thoracic Aortic Aneurysm and Cancer of the Right Lung.

75歳, 女性の右肺癌 (IA) 合併胸部下行大動脈瘤に対して, 肺癌手術に先行させて局所麻酔下に胸部大動脈瘤に対するステントグラフト内挿術 (Dacron sheet で被覆した自己拡張型の spiral Z stent) を行った. 造影上 endoleak は認めず瘤は消失した. 肺癌合併胸部大動脈瘤では癌の根治性から同時手術が望ましいと考えられるが, 本例のような高齢者右肺癌合併例の場合, 同時手術はもちろん, 二期的手術を選択しても両側開胸に伴う手術リスクの増大が危惧される. ステントグラフト内挿術は呼吸機能低下や手術操作, 全身麻酔, 輸血などに伴う免疫能低下を懸念する必要がなく, 癌進行の点からも有利に早期の二期的肺癌手術を設定することが可能であった.