Hideki Yao

Prevention and detection of spinal cord injury during thoracic and thoracoabdominal aortic repairs

BACKGROUNDnSpinal cord injury is a most dreaded and unpredictable complication. In this study, based on our experimental results in dogs and early clinical results, we reviewed the incidence of paraplegia and the detection of spinal cord injury.nnnMETHODSnEighty-two patients who underwent elective surgical repair of the descending thoracic and thoracoabdominal aorta over 17 years were subjects for this study. Sixty-two patients were male and 20 were female. Their mean age was 61.6 years (range, 17 to 81 years). Monitoring somatosensory evoked potentials (SEP) and measurement of mean distal aortic pressure and cerebrospinal fluid pressure were performed perioperatively.nnnRESULTSnSixty patients had no ischemic change in SEP. In 17 patients with significant ischemic changes of SEP, SEP recovered by increasing spinal cord perfusion pressure to more than 40 mm Hg. Two patients with complete loss of SEP experienced paraplegia. One patient had delayed paraplegia.nnnCONCLUSIONSnThese results strongly suggest that SEP, mean distal aortic pressure, cerebrospinal fluid pressure should be monitored during aortic cross-clamping. Maintaining spinal cord perfusion pressure at more than 40 mm Hg by increasing mean distal aortic pressure or withdrawal of cerebrospinal fluid is valuable for preventing paraplegia.

Candida parapsilosis endocarditis that emerged 2 years after abdominal surgery.

A 22-year-old man was hospitalized after 3 months of persistent fever and malaise. He had undergone abdominal surgery 24 months before admission. Echocardiography demonstrated two mobile pedunculated masses in the right ventricle. Multiple blood cultures were positive for Candida parapsilosis. After 4 weeks of miconazole treatment, the two masses were excised via a right atriotomy incision and the transtricuspid value approach. Histological examination revealed that they were fungal vegetation. Antifungal agents were continued for 1 year after surgery. The patient has remained well with no further symptoms for 3 years. This case suggests the necessity for careful evaluation of past history to avoid diagnostic delay in fungal endocarditis.

Long-term results of mitral valve replacement: biological xenograft versus mechanical valves

Abstractu2002We studied 279 patients who underwent mitral valve replacement at the Department of Thoracic and Cardiovascular Surgery, Hyogo College of Medicine, between November 1973 and December 1998. The patients were divided into two groups based on the type of replacement valve (154 patients in the biological xenograft group and 125 patients in the mechanical valve group), and the long-term results were compared. Clinically satisfactory results were obtained in both the biological xenograft group and the mechanical valve group according to the surgical results, long-term survival, and incidence of prosthetic valve endocarditis. At 15 years, fewer patients in the mechanical valve group than in the biological xenograft group were free of bleeding events (92.5 ± 3.7% vs 100% P < 0.05). At 15 years, the biological xenograft group was lower than the mechanical valve group with respect to freedom from thromboembolism (72.2 ± 4.6% vs 93.5 ± 3.6% P < 0.01), freedom from valve failure (22.0 ± 5.2% vs 87.0 ± 4.1% P < 0.005) and freedom from cardiac events (16.5 ± 3.9% vs 47.2 ± 14.5% P < 0.01). Though it has previously been suggested that biological xenografts used in mitral valve replacement do not need anticoagulation, the current study suggests the need for anticoagulation with the use of biological xenografts. Mechanical valves require close monitoring of anticoagulation, but their use has decreased the incidence of valve failure and thromboembolism, as compared with the use of biological xenografts. Therefore, mechanical valves are currently the preferred choice for mitral valve replacement. We believe that biological xenografts are indicated only for the older patient (≧65 years).

Angiosarcoma of the pericardium. Review of 9 reports from Japan.

A 35-year-old woman diagnosed with a cardiac tumor by echocardiography and cinecardiography underwent surgical excision in December 1988. The port-wine tumor had invaded from the surface of the right atrium to the anterior wall of the right ventricle, preventing us from removing it completely. Pathohistologically, it was diagnosed as angiosarcoma of the pericardium. She died due to lung metastasis on the postoperative day 107. To our knowledge, only 9 such cases have been reported in Japan.

Serum monocyte chemoattractant protein-1 levels in rat models of intimal hyperplasia

Recently we reported that there is a direct correlation between monocytes/macrophages (Mo/Mø) infiltration and the development of intimal hyperplasia (IH) in rat interposition vein graft. Monocyte chemoattractant protein-1 (MCP-1) is the most potent chemoattractant and activating chemokine for Mo/Mø. We evaluated rat serum MCP-1 levels as the indicator of inflammatory response, before and after operation. In twenty five male Lewis rats (484±7 g) we interposed epigastric vein graft into the right common femoral artery. Rat serum MCP-1 levels were measured before skin incision and before and after bypass (0 hour, two weeks and four weeks), using enzyme linked-immuno-sorbent assay method. Rat serum MCP-1 levels were significantly increased at 0 hour (154 pg/ml,p<0.05), two weeks (187 pg/ml,p<0.01) and four weeks (169 ng/ml,p<0.01), compared to before skin incision (87 pg/ml). These results suggest that the prolongation of inflammatory response may cause the development of IH in rat interposition vein grafts.

Accessory Mitral Valve Associated with Aortic Regurgitation in an Elderly Patient : Report of a Case

We encountered a 75-year-old man who complained of exertional dyspnea. An echocardiographic examination showed aortic regurgitation and a tumor in the left ventricular outflow tract. Under complete extracorporeal circulation, we surgically made an incision of the ascending aorta with a slight thickening of the aortic valve and an enlarged annulus. After excising the aortic valve, an examination of the subvalvular region revealed mitral valve-like tissue extending from the annular region of the right coronary cusp to the ventricular septum, while the chordae tendinae was attached to the septum. This issue was excised, and the aortic valve was replaced with a 27-mm SJM® valve. The postoperative course was uneventful, and the patient was discharged in good condition on postoperative day 30. An accessory mitral valve is extremely rare. Since this indication for surgical treatment is associated with congenital heart disease or a left ventricular outflow tract obstruction, most patients are young. Our patient had no associated cardiac anomalies and no pressure gradient attributable to a left ventricular outflow tract obstruction. This accessory mitral valve was discovered during aortic valve replacement surgery. To our knowledge, our patient is the oldest reported with an accessory mitral valve to have undergone a surgical resection.

Subarachnoid venous hemorrhage in a patient with retrograde cerebral perfusion during surgery for a thoracic aortic aneurysm

Prior to surgery, a silicone subarachnoidal drainage tube [Silascon (Kaneka Medix, Osaka, Japan), 5Fr] was inserted from L3 to L4 (5cm on the cephalad side) to monitor cerebrospinal pressure and to facilitate the suction of cerebrospinal fluid. The patient was positioned for left posterolateral thoracotomy. The cardiopulmonary bypass was obtained by cannulating the right femoral artery and vein, and the pulmonary artery. The venous cannula was advanced to the right atrium, and then the patient was cooled until a blood temperature of 23.5°C and rectal temperature of 25.4°C were reached. Methylprednisolone (1g) and pentobarbital (250mg) were given during cooling. Upon circulatory arrest, the patient was placed in the Trendelenburg position and his head was wrapped in a cold ice bag. The circulation was arrested for 28min. Simultaneously, retrograde cerebral perfusion was performed through the right atrium, and the flow rate was controlled at around 600ml·min21. During the retrograde cerebral perfusion, the right atrial pressure was about 10mmHg. Under additional circulatory arrest (11min), aortocoronary bypass grafting involving one branch was performed. The blood supply to the upper body was resumed through the replaced thoracic aorta. The blood supply to the lower body was resumed through the femoral artery. Anastomosis on the peripheral side was performed. The duration of aortic clamping was 49min. The duration of extracorporeal circulation was 2h 19 min.

Prevention of Spinal Cord Injury During Thoracic and Thoracoabdominal Aortic Repairs

Spinal cord injury is the most dreaded, unpredictable complication following repair of the descending thoracic and thoracoabdominal aorta. In this study, based on our experimental results in dogs and early clinical results we reviewed the incidence of paraplegia and the perioperative detection of spinal cord injury. Between October 1, 1985 and June 31, 1999 a total of 73 patients who underwent elective surgical repair of the descending thoracic and thoracoabdominal aorta entered the study. Somatosensory evoked potentials (SEPs) were monitored, and the mean distal aortic pressure (MDAP) and cerebrospinal fluid pressure (CSFP) were measured perioperatively. No patients developed paraplegia in this study, although one patient with significant changes in SEP, whose spinal cord perfusion pressure (SCPP) was 60 mmHg, developed delayed paraplegia. Another 20 of the remaining 72 patients showed significant ischemic changes in the SEP; in 13 of these 20 patients the SEP gradually recovered by increasing the SCPP up to more than 40 mmHg. In 51 of the other 53 patients without ischemic SEP changes, the SCPP was kept at more than 40 mmHg; the other two patients did not develop paraplegia. These results strongly suggest that SEP, MDAP, and CSFP should be monitored during aortic repairs. Moreover, maintaining the SCPP at more than 40 mmHg by increasing the MDAP, withdrawing cerebrospinal fluid, or both valuable for preventing paraplegia.