Kunikazu Hisamochi

Nitric oxide inhibition attenuates systemic hypotension produced by protamine

BACKGROUNDnProtamine reversal of heparin anticoagulation often causes systemic hypotension, and in vitro studies suggest that this may be mediated by release of nitric oxide from the endothelium. The present investigations were designed to evaluate the direct myocardial effects of protamine and to determine in vivo whether nitric oxide inhibition can prevent hypotension during protamine infusion.nnnMETHODS/RESULTSnProtamine sulfate (50 microg/ml) was added to perfusate of eight isolated rabbit heart preparations; in six other preparations, a similar concentration of prolamine was added to heparinized (5 U/ml) Krebs perfusate. Left ventricular developed pressure, maximum rate of pressure rise, and heart rate declined significantly (p < 0.01) in hearts exposed to protamine only (65.0% +/- 6.6%, 55.5% +/- 6.0%, and 87.6% +/- 2.5% of baseline, respectively), whereas protamine added to heparinized perfusate caused little change in developed pressure, maximum rate of pressure rise, and heart rate (85.3% +/- 5.4%, 84.9% +/- 5.5%, and 98.8% +/- 1.6%). To study systemic effects of protamine, we measured hemodynamic parameters in 12 heparinized dogs (150 U/kg). During protamine infusion (1.5 mg/kg intravenously over 30 seconds), mean blood pressure decreased by 46% +/- 7% from baseline (P < 0.05), cardiac output decreased by 38% +/- 4% (p < 0.05), and systemic vascular resistance decreased bv by 14& +/- 9%. After hemodynamic stabilization, Ng-monomethyl-L-arginine (2 mg/kg), a competitive inhibitor of nitric oxide synthesis, was administered to six dogs, and methylene blue (2 mg/kg), an inhibitor of cyclic guanosine monophosphate synthesis, was administered to the remaining six dogs. After treatment with Ng-monomethyl-L-arginine and methylene blue, the second infusion of protamine sulfate caused no significant change in blood pressure or cardiac output. In an additional six dogs, Ng-monomethyl-L-arginine pretreatment (5 mg/kg) blocked the effects of the first dose of protamine. The effect of Ng-monomethyl-L-arginine could be reversed by the addition of (6 mg/kg) L-arginine but not D-arginine.nnnCONCLUSIONSnProtamine-heparin complex does not cause direct myocardial depression but does lead to severe hypotension in vivo. The finding that hypotension can be blocked by inhibitors of the nitric oxide pathway confirms previous in vitro studies indicating that the effects of protamine are mediated, in part, by the vascular endothelium. Further, these studies suggest a novel approach to prevention of hemodynamic complications caused by heparin reversal after cardiopulmonary bypass.

A model of xenograft hyperacute rejection attenuates endothelial nitric oxide production: A mechanism for graft vasospasm?

BACKGROUNDnThe deposition of complement components within grafts, complement consumption, and prolongation of graft function by complement inactivation imply a pivotal role for complement in xenograft hyperacute rejection. The current investigations examined the endothelial production of vasoactive substances in pulmonary arteries during simulated hyperacute rejection.nnnMETHODS AND RESULTSnCanine pulmonary arteries were suspended in organ chambers and exposed to either autologous canine serum for 90 minutes or heterologous porcine serum for 30, 60, or 90 minutes. Following serum exposure, the vessels were allowed a one-hour equilibration in buffered crystalloid solution. Dose-response curves were obtained with acetylcholine, sodium nitroprusside, and calcium ionophore A23187 following contraction with phenylephrine (10(-6) M) in the presence of indomethacin (10(-5) M). Receptor-dependent, endothelial-dependent relaxations to acetylcholine (10(-9)-10(-4) M) were impaired with 30-, 60-, or 90-minute porcine serum exposure when compared to vessels exposed to autologous canine serum (n = 10, 7, 9, respectively; p < .05; 2-way ANOVA). Receptor-independent, endothelial-dependent relaxations to calcium inophore (10(-9)-10(-6) M) were significantly impaired at 60- and 90-minute porcine exposures only (n = 7, 8; p < .05). Endothelial-independent relaxations to sodium nitroprusside (10(-9)-10(-4) M) were not impaired with either canine or porcine serum exposure. Oxyhemoglobin (10(-6) M) abolished acetylcholine-mediated relaxations, indicating that nitric oxide was the predominant mediator.nnnCONCLUSIONSnSimulated hyperacute xenograft rejection impairs endothelium-dependent relaxation of canine pulmonary arteries. Both basal and stimulated production of nitric oxide is impaired by heterologous serum exposure and, subsequently, complement activation. Reduced production of nitric oxide may explain, in part, the vasospasm and thrombosis of xenografts during hyperacute rejection.

Innominate artery cannulation for arterial perfusion during aortic arch surgery.

Antegrade cerebral perfusion during aortic arch surgery plays an important role in improving postoperative neurological outcomes. We report our experience using innominate artery cannulation for arterial perfusion during aortic arch surgery.

Spinal cord protection during thoracoabdominal aortic replacement: spinal cord perfusion maintenance

OBJECTIVESnSpinal cord protection during thoracoabdominal aortic surgery is challenging for surgeons. We performed thoracoabdominal replacement using a strategy for maintaining spinal cord perfusion pressure. Here, we report our experience with this procedure and the surgical outcomes.nnnMETHODSnBetween January 2000 and December 2014, 130 patients [male: 91 (74.6%), female: 39 (25.4%); mean age: 66.6u2009±u200912.8 years] underwent thoracoabdominal replacement using cardiopulmonary bypass at Hiroshima Shimin Hospital, Japan. The surgical outcomes of these patients were analysed.nnnRESULTSnThe in-hospital mortality rate of all patients was 2.5%. The incidence of postoperative paraplegia was 3.8%. Aortic event-free survival rates at 1, 3 and 5 years were 98.2%, 93.9% and 80.7%, respectively.nnnCONCLUSIONSnThe present study suggests that our strategy for maintaining spinal cord perfusion pressure provides acceptable outcomes.

Operative results of the anterolateral thoracotomy with partial sternotomy approach for chronic-type B aortic dissection involving the aortic arch

ObjectivesnThere are various treatment strategies for chronic-type B aortic dissection involving the aortic arch. Our aim was to review our surgical experience in the anterolateral thoracotomy with the partial sternotomy approach for chronic-type B aortic dissection involving the aortic arch.nnnMethodsnFrom January 2000 to October 2015, 39 patients underwent the single-stage open surgery for chronic-type B aortic dissection involving the aortic arch using the anterolateral thoracotomy with partial sternotomy approach.nnnResultsnAmong the 39 patients, 32 were men (82.1%; mean age at surgery, 61.3u2009±u200911.9 years), with a mean dissecting aortic aneurysm diameter of 50.21u2009±u200912.20u2009mm; 28 patients (71.8%) had patent false lumens of the descending aorta. The median interval from dissection occurrence until surgery was 34.05u2009±u200952.34 months. Twenty-one patients underwent descending aortic replacement plus total aortic arch replacement and 18 underwent descending aortic replacement (plus partial aortic arch replacement). Overall in-hospital mortality and postoperative stroke rates were 5.1% (2 patients) and 10.3% (4 patients), respectively. Survival rates at 1, 3 and 5 years were 94.7%, 94.7% and 90.2%, respectively. Aortic event-free rates at 1, 3 and 5 years were 90.9%, 90.9% and 80.2%, respectively.nnnConclusionsnThe anterolateral thoracotomy with partial sternotomy approach is a useful surgical procedure with acceptable outcomes for chronic-type B aortic dissection cases involving the aortic arch, when aortic remodelling using thoracic endovascular aortic repair cannot be performed.

Outlet strut fracture and leaflet escape of Bjork–Shiley convexo–concave valve

Prosthetic valve fracture is a serious complication and may arise in patient post-valve replacement. We experienced an outlet strut fracture and leaflet escape of a Bjork–Shiley convexo–concave valve. We performed an emergency redo mitral valve replacement and successfully retrieved the fractured strut and escaped leaflet from superficial femoral artery and the abdominal aorta. The patient showed an uneventful postoperative recovery.

Outcomes of Anterolateral Thoracotomy With or Without Partial Sternotomy for Kommerell Diverticulum

BACKGROUNDnKommerell diverticulum is a rare aortic arch anomaly. The indications for operative intervention and surgical strategy are still controversial. The standard surgical procedure at our institution is total aortic arch plus descending aortic replacement using anterolateral thoracotomy with partial sternotomy. The aberrant subclavian artery is reconstructed anatomically or extraanatomically.nnnMETHODSnFrom 2002 to 2014, 6 patients (1 woman), aged 55 to 78 years, underwent graft replacement through an anterolateral thoracotomy or anterolateral thoracotomy with a partial sternotomy approach for Kommerell diverticulum. All patients underwent graft replacement of the descending aorta or total aortic arch plus descending aorta in addition to aberrant subclavian artery reconstruction.nnnRESULTSnNo hospital deaths or major complications occurred. Recurrent nerve injury developed at discharge in 1 patient. All patients were well during the follow-up period (range, 11 to 116 months).nnnCONCLUSIONSnKommerell diverticulum and its associated symptoms were surgically treated with acceptable outcomes.

Cardiac resynchronization therapy for ischemic myopathy.

We performed coronary artery grafting, mitral valve plasty, and tricuspid plasty in a 75-year-old man who had double-vessel coronary disease and moderate mitral and tricuspid insufficiency. Preoperative transthoracic echocardiography revealed an ejection fraction of 34% and dyssynchronous wall motion of the septum and free wall. We placed pacing leads on the right ventricular outlet and posterior left ventricular wall for cardiac resynchronization therapy. The dyssynchrony disappeared postoperatively and the New York Heart Association functional class improved from IV to I.

A case of matured mediastinal teratoma complicated by cardiac tamponade: an unusual aetiology: Images for surgeons

Mediastinal teratoma often grows to a large size and becomes adherent to the surrounding cardiopulmonary structures. Although a mature mediastinal teratoma is histologically diagnosed as benign, the inflammatory adhesion around the tumour sometimes makes surgical management difficult and invasive. Moreover, perforation of the tumour into the pericardial sac causes cardiac tamponade, a rare but life-threatening complication. The mechanism of perforation into the adjacent structures remains controversial. We describe a case of mature mediastinal teratoma complicated by cardiac tamponade caused by pressure necrosis of a small cyst within tumour. A 9-year-old previously healthy Japanese girl was referred to us because of severe dyspnoea and chest pain, which had developed 4 months previously. On the day of admission, she complained of sudden worsening of symptoms. On admission, she was pale, tachypnoeic (55/minute), tachycardic (98/minute) and hypotensive (systolic 88, diastolic 44 mmHg). Her electrocardiogram (ECG) was normal. The respiratory sounds over the right side of the chest were faint, but the heart sounds were normal. The white blood count was 14 600/mm, and the serum C-reactive protein was 2.1 mg/dL. A chest radiography revealed a tumour of 10 cm in diameter in the anterior mediastinum (Fig. 1). A computed tomography demonstrated a calcified, partly cystic tumour with thickened wall in the anterior mediastinum, massive pericardial effusion and narrowing of the superior vena cava (Fig. 2). Echocardiogram confirmed the pericardial effusion and demonstrated poor cardiac wall motion. A right thoracotomy was performed to enter the pleural cavity. The large tumour was firmly adherent to the pericardium, superior vena cava and thymus. A large amount of bloody debris in the cyst were removed. Because of dense adhesion, the pericardium was partly excised along with the tumour, but no apparent hole was identified in the pericardium. Histopathological examination revealed a tumour composed of cartilage, glands and various foci of epithelium, associated with inflammatory granulation tissue. The final diagnosis was mature teratoma of thymus. The patient had an uneventful post-operative course except asymptomatic arrhythmia. She is free of symptoms 5 years after surgery. Mediastinal teratoma is rare in children, accounting for 4.3% of all germ cell tumours; however, it is one of the most common lesions found in the anterior mediastinum, accounting for 8–13% of all mediastinal tumours. About 30% of all mediastinal neoplasms and cysts appear in the first two decades of life. In later childhood, symptoms are rare, especially from benign tumours, and about one third of mediastinal masses are detected by routine chest radiography. The tumour is associated with numerous potential life-threatening complications. In particular, a high incidence of fistulae formation into the bronchial tree has been reported. Spontaneous rupture of

A case of matured mediastinal teratoma complicated by cardiac tamponade: an unusual aetiology

Mediastinal teratoma often grows to a large size and becomes adherent to the surrounding cardiopulmonary structures. Although a mature mediastinal teratoma is histologically diagnosed as benign, the inflammatory adhesion around the tumour sometimes makes surgical management difficult and invasive. Moreover, perforation of the tumour into the pericardial sac causes cardiac tamponade, a rare but life-threatening complication. The mechanism of perforation into the adjacent structures remains controversial. We describe a case of mature mediastinal teratoma complicated by cardiac tamponade caused by pressure necrosis of a small cyst within tumour. A 9-year-old previously healthy Japanese girl was referred to us because of severe dyspnoea and chest pain, which had developed 4 months previously. On the day of admission, she complained of sudden worsening of symptoms. On admission, she was pale, tachypnoeic (55/minute), tachycardic (98/minute) and hypotensive (systolic 88, diastolic 44 mmHg). Her electrocardiogram (ECG) was normal. The respiratory sounds over the right side of the chest were faint, but the heart sounds were normal. The white blood count was 14 600/mm, and the serum C-reactive protein was 2.1 mg/dL. A chest radiography revealed a tumour of 10 cm in diameter in the anterior mediastinum (Fig. 1). A computed tomography demonstrated a calcified, partly cystic tumour with thickened wall in the anterior mediastinum, massive pericardial effusion and narrowing of the superior vena cava (Fig. 2). Echocardiogram confirmed the pericardial effusion and demonstrated poor cardiac wall motion. A right thoracotomy was performed to enter the pleural cavity. The large tumour was firmly adherent to the pericardium, superior vena cava and thymus. A large amount of bloody debris in the cyst were removed. Because of dense adhesion, the pericardium was partly excised along with the tumour, but no apparent hole was identified in the pericardium. Histopathological examination revealed a tumour composed of cartilage, glands and various foci of epithelium, associated with inflammatory granulation tissue. The final diagnosis was mature teratoma of thymus. The patient had an uneventful post-operative course except asymptomatic arrhythmia. She is free of symptoms 5 years after surgery. Mediastinal teratoma is rare in children, accounting for 4.3% of all germ cell tumours; however, it is one of the most common lesions found in the anterior mediastinum, accounting for 8–13% of all mediastinal tumours. About 30% of all mediastinal neoplasms and cysts appear in the first two decades of life. In later childhood, symptoms are rare, especially from benign tumours, and about one third of mediastinal masses are detected by routine chest radiography. The tumour is associated with numerous potential life-threatening complications. In particular, a high incidence of fistulae formation into the bronchial tree has been reported. Spontaneous rupture of