Manabu Hisahara

Effects of hypothermia during cardiopulmonary bypass and circulatory arrest on sympathetic nerve activity in rabbits

OBJECTIVES Little is known about the effect of hypothermia on neural regulation. We investigated the effects of hypothermia during cardiopulmonary bypass (CPB) on control of renal (RSNA) and lumbar sympathetic nerve activity (LSNA), and plasma catecholamine levels. METHODS We directly measured RSNA (n = 14) and LSNA (n = 6) during CPB in anesthetized rabbits. CPB was performed via cannulae in the aortic root for arterial perfusion and the right atrium for venous drainage. Systemic hypothermia was induced by core cooling. RSNA and LSNA were recorded at the nasopharyngeal temperature of 37, 30, 24, and 18 degrees C and after rewarming up to 37 degrees C while keeping mean arterial pressure at 70 mmHg by altering perfusion flow. Other variables such as blood gases or electrolytes were kept constant. RESULTS RSNA at the temperature of 30, 24, and 18 degrees C significantly decreased by 91, 97, and 95% from control (37 degrees C), respectively. LSNA decreased by 18, 57, and 89% from control as well. The decreases in RSNA at 30 and 24 degrees C were greater than those in LSNA (P < 0.05). At 18 degrees C both RSNA and LSNA nearly disappeared. Circulatory arrest for 20 min during hypothermia at 18 degrees C caused no increase in RSNA while it increased LSNA. Plasma catecholamine levels at 18 degrees C were not different from those at 37 degrees C. Rewarming to 37 degrees C increased RSNA and LSNA by 321 and 92% from control (37 degrees C before cooling), respectively (P < 0.01). CONCLUSIONS Hypothermia progressively decreased and rewarming markedly increased sympathetic nerve activity, but the effects of hypothermia on RSNA and LSNA were not uniform.

Inhibition of lipid peroxidation with the lazaroid U74500A attenuates ischemia-reperfusion injury in a canine orthotopic heart transplantation model☆☆☆★★★♢

BACKGROUND The lazaroid U74500A is a 21-aminosteroid that inhibits lipid peroxidation and attenuates ischemia-reperfusion injury. We examined the effect of U74500A on heart preservation with the use of a clinically relevant canine orthotopic heart transplantation model. METHODS AND RESULTS Six donor dogs (group L) were pretreated intravenously with U74500A (10 mg/kg), and the dogs without pretreatment served as a control (group C, n = 6). The donor heart was preserved in cold University of Wisconsin solution for 24 hours. The heart was then transplanted orthotopically. Myocardial biopsy was performed to measure the adenosine triphosphate level at the end of ischemia. Before reperfusion, recipients in group L received another dose of U74500A (10 mg/kg) intravenously. After 3 hours of reperfusion, left ventricular function was evaluated by left ventricular pressure-volume relations with the use of a Millar catheter and conductance catheter, thereby deriving the slope of the end-systolic pressure-volume relation, the slope of the stroke work-- end-diastolic volume relation, and the slope of the maximum dP/dt--end-diastolic volume relation. At the same time, serum creatine kinase MB isoenzyme and lipid peroxide levels were measured. The slopes of the end-systolic pressure-volume relation, the stroke work--end-diastolic volume relation, and the maximum dP/dt--end-diastolic volume relation for group L were significantly higher than those for group C. The adenosine triphosphate levels for group L were significantly higher than those for group C. Serum creatine kinase MB isoenzyme and lipid peroxide levels for group L were significantly lower than those for group C. CONCLUSIONS Inhibition of lipid peroxidation by the administration of U74500A was effective for 24-hour canine cardiac preservation. These results indicate that U74500A is a promising agent for heart allograft preservation.

Arresting donor hearts with extracellular-type cardioplegia prevents vasoconstriction induced by UW solution.

The effects of arresting donor hearts with University of Wisconsin solution was investigated. Donor dogs were divided into two groups according to the technique used for arresting the heart. In group I (n = 6) the heart was arrested with University of Wisconsin solution, whereas in group II (n = 6) extracellular-type cardioplegia (K+ = 20 mmol/liter) was used to induce cardioplegic arrest. Aortic root pressure was measured during the infusion of solution at constant flow. In both groups, the hearts were then flushed and stored in cold University of Wisconsin solution for 6 h. The hearts were transplanted orthotopically and disconnected from cardiopulmonary bypass. Left ventricular function was evaluated by pressure-volume relations using a conductance catheter. Peak aortic root pressure during the infusion was significantly higher in group I than in group II, although post-transplant left ventricular function was similar in both groups. Although there was no difference in cardiac function after implantation, donor hearts should be arrested by extracellular-type cardioplegia to prevent coronary vasoconstriction associated with preservation in University of Wisconsin solution.

Bilateral Axillary Arterial Perfusion in Surgery on Thoracic Aorta

Bilateral axillary arterial cannulation for selective cerebral perfusion might minimize cerebral embolic complications during surgery on the ascending aorta and aortic arch. From March 2002 through February 2004, bilateral axillary arterial perfusion was applied in 12 consecutive patients (mean age, 61.3 years). Operative procedures were total arch replacement in 8 patients, hemiarch replacement in 1, and ascending aorta replacement in 3. Antegrade selective cerebral perfusion was established through vascular grafts anastomosed to the bilateral axillary arteries and a perfusion catheter placed directly into the left carotid artery. Bilateral axillary arterial perfusion through the grafts was successful in all patients. There were no early or late deaths and no incidence of neurologic deficit. There were no complications related to cannulation of the axillary arteries. Bleeding, temporary renal failure, acute respiratory distress syndrome, and graft infection occurred in one patient each; all recovered from these complications. Bilateral axillary arterial perfusion is feasible and effective for brain protection during surgery on the ascending aorta and aortic arch.

The relationship between functional class, pulmonary artery pressure and size in left atrial myxoma.

To examine the correlation between the size of left atrial myxoma, the degree of pulmonary hypertension and the patients New York Heart Association (NYHA) functional class, the records of 29 surgically treated patients with left atrial myxoma were reviewed. Of 29 patients, 23 were catheterized before surgery. As the preoperative NYHA functional class advanced, the preoperative mean pulmonary artery pressure (mmHg) was seen to increase. Moreover, the weight of the excised myxoma also correlated well with the preoperative pulmonary artery pressure value. In five patients inserted with a Swan-Ganz catheter, the mean pulmonary artery pressure decreased immediately after tumour excision. Postoperatively, the average NYHA class of the 29 patients significantly improved. These results confirmed the positive correlation between the size of the tumour, the pulmonary artery pressure, and NYHA class in patients with left atrial myxoma.

Tranexamic acid reduces blood loss after cardiopulmonary bypass

To evaluate the effect of tranexamic acid (TA) on blood loss after cardiopulmonary bypass (CPB), 157 patients who underwent elective valve replacement operations were studied, with one group of 90 patients receiving tranexamic acid (Group TA) and 67 patients serving as the control group (Group N). In group TA, 50 mg/kg of tranexamic acid was administered just before and after CPB, and every 90 minutes during CPB. The activated coagulation time was maintained at more than 450 seconds during CPB in both groups. There was no significant difference in the CPB time between the groups (163 +/- 32 min in group N and 152 +/- 38 min in group TA:NS). The time required for hemostasis was shortened in group TA, which resulted in a shorter operation time (6.7 +/- 1.5 hrs vs 6.0 +/- 1.5 hrs in group N and group TA, respectively: p = 0.006). The amount of chest tube drainage within 12 hours after surgery was significantly reduced (225 +/- 129 ml vs. 180 +/- 118 ml in group N and group TA, respectively: p = 0.026). The chest tube was able to be removed earlier in group TA, and the total blood loss was significantly smaller in group TA (402 +/- 292 ml) than in group N (631 +/- 609 ml; p = 0.004). The authors thus conclude that antifibrinolytic therapy during CPB with tranexamic acid reduces postoperative blood loss, and shortens the operation time due to an improvement in hemostasis.

An Unusual Manifestation of Brain Tumor: Development of Delayed Hemiplegia After Cardiopulmonary Bypass

Abstract  Cerebral swelling after cardiopulmonary bypass might trigger a critical cerebral consequence resulting from intracranial space‐occupying lesion. We experienced a 75‐year‐old woman who suffered from a delayed left hemiplegia after mitral valve replacement. Urgent diagnostic imaging revealed the presence of a brain tumor with perifocal cerebral edema. Fluid shifts occurring within a few days after the cardiopulmonary bypass, manifesting the focal cerebral edema, played a key role in this unique clinical course.

Cor triatriatum repair to eliminate suffering from paroxysmal atrial fibrillation

Development of atrial fibrillation is one of the primary indicators of cor triatriatum in adults. Here we describe a case of a patient suffering cor triatriatum coexistent with frequent paroxysmal atrial fibrillation. Paroxysms of arrhythmia were not encountered after surgical correction. Resection of an anomalous membranous septum may have contributed to interrupting the development of ectopic beats, eliminating paroxysmal atrial fibrillation.

Drug infusion through a branch of the aortocoronary vein graft for refractory coronary spasm

We describe two cases of coronary artery spasm that occurred during open heart operations and were treated by coronary artery bypass grafting. Vasodilators and calcium antagonists were infused directly into the right coronary artery via the side branch of the saphenous vein graft. Both patients were weaned successfully from cardiopulmonary bypass.

Bilateral Axillary Artery Perfusion to Reduce Brain Damage during Cardiopulmonary Bypass

Abstract  Background: Theoretically, a multiple perfusion approach, reducing detachment of atheromatous debris from the aortic intima and its flow into the cerebral circulation, should contribute to lessen a stroke, and may be applied to complex cardiac surgery with extensive aortic disease. The aim of the present study was to examine the value of bilateral axillary artery perfusion during thoracic aortic and cardiac surgery, and to evaluate the clinical results with a particular focus on cerebral damage. Methods: From March 2002 through December 2007, 24 patients (16 male and eight female; age range, 43 to 84 years) underwent bilateral axillary artery perfusion through side grafts during cardiopulmonary bypass. Aortic surgery, including total arch replacement, hemiarch replacement, and ascending aortic replacement, was performed in 21 patients. Bilateral axillary artery perfusion was also used in three complicated valve surgeries after expanding its indication to cardiac pathology with a diseased aorta, two redo cases with severe atherosclerotic vascular disease, and one case with a porcelain aorta. Results: Bilateral axillary artery perfusion was successful in all patients. There were no complications related to this procedure except in one patient, who suffered from a local fluid retention in one wound, requiring puncture drainage. There was no hospital mortality. No strokes were identified by either clinical assessments or diagnostic imaging. Conclusions: Bilateral axillary artery perfusion is a useful method for protection of the brain during either thoracic aortic or cardiac surgery when the patients have an extensively diseased aorta. (J Card Surg 2010;25:139‐142)