Takuro Misaki

Effect of low-dose aprotinin on coagulation and fibrinolysis in cardiopulmonary bypass.

To study the effect of low-dose aprotinin on hemostasis in patients undergoing cardiopulmonary bypass (CPB) for coronary artery bypass operations and to elucidate the mechanism of aprotinin action, we randomized 14 of 27 patients to receive 30,000 KIU/kg aprotinin in the CPB priming volume and 7,500 KIU/kg aprotinin intravenously each hour during CPB (1 patient was excluded from the aprotinin group because of protamine shock). Intraoperative and postoperative blood loss was significantly reduced in the aprotinin group. Antithrombin III level was significantly decreased, and the levels of thrombin-antithrombin III complexes were significantly increased during CPB in both groups, indicating activation of the clotting system. The marked increase in fibrin(ogen) degradation products during CPB in the control group, indicating enhanced fibrinolytic activity, was significantly reduced in the aprotinin group. alpha 2-Plasmin inhibitor was significantly reduced during CPB in the control group. The marked increase in alpha 2-plasmin inhibitor-plasmin complexes in the control group, indicating plasmin activity, was significantly reduced in the aprotinin group. A marked decrease in the platelet count was observed during CPB similarly in both groups. These findings demonstrated that low-dose aprotinin administration was effective in reducing intraoperative and postoperative blood loss and that activation of the clotting system during CPB was not followed by hyperfibrinolysis in aprotinin-treated patients. The improved hemostasis is mainly attributable to the prevention of hyperfibrinolysis during CPB.

Nuclear tomographic phase analysis: Localization of accessory conduction pathway in patients with Wolff-Parkinson-White syndrome

The purpose of this study was to evaluate the usefulness of tomographic phase analysis in detecting the site of the accessory conduction pathway (ACP) in patients with Wolff-Parkinson-White (WPW) syndrome. Gated emission computed tomography and planar gated blood pool scintigraphy were performed in 20 patients with WPW syndrome, 14 with delta waves and six without delta waves (two intermittent types and four concealed types). The abnormal initial contractions in both planar and tomographic phase images were compared with the sites of ACPs confirmed by epicardial mapping and surgery. The atrioventricular ring was divided into eight segments on each side, and the identification of the initial phase in the segment in which the ACP was located, or that adjacent to it, was considered to be the correct diagnosis. In planar phase analysis, the abnormal initial phase was identified correctly in 8 of 14 patients (57%), whereas in tomographic phase analysis, the site of the ACP was detected in 12 of 14 patients (86%). Tomographic phase analysis can be a helpful adjunctive method in patients with WPW syndrome.

Interruption of multiple accessory conduction pathways in the Wolff-Parkinson-White syndrome

Of 35 patients with Wolff-Parkinson-White syndrome operated on, 5 were seen with two accesory conduction pathways each; all of these were successfully interrupted. In one patient, one accessory conduction pathway each was located in the right and left side of the heart; in the other 4, both pathways were confined to the right side. In 2 patients with unilateral (right side) multiple accessory conduction pathways, Ebsteins anomaly was also present. In 1 patient with Ebsteins anomaly, the second unilateral accessory conduction pathway was discovered intraoperatively and was successfully interrupted. The remaining 4 patients required a second operation to interrupt the other pathway. A delta wave completely different from the preoperative one appeared 4 to 10 days after interruption of the first major pathway, and the second operation was performed 14 days, 42 days, four months, or five years after the first operation. All 5 patients survived, and long-term follow-up revealed no signs of morbidity.

Efficacy of a skeletal muscle—powered dynamic patch: Part 1. Left ventricular assistance

In this study, we examined the capability of a skeletal muscle-powered, dynamic patch to provide left ventricular assistance. An actuator was developed that used linear traction power furnished by the latissimus dorsi muscle and liquid as the medium for power transfer. The proximal portion of the muscle was dissected and was reattached to the actuator. The left ventricular apex was excised, and the dynamic patch lined with autologous pericardium was implanted during cardiopulmonary bypass. Hemodynamic studies were performed in 8 dogs after weaning from cardiopulmonary bypass. Muscle stimulation was found to significantly increase the systolic aortic pressure (91.6 versus 112.1 mm Hg; p < 0.01), the mean aortic pressure (65.2 versus 73.0 mm Hg; p < 0.01), and aortic blood flow (0.77 versus 0.92 L/min; p < 0.01). The left atrial pressure decreased from 17.9 to 16.6 mm Hg (p < 0.01). This hybrid left ventricular assist device possesses notable clinical advantages because of its remarkable efficacy in assisting circulation. Further experimental studies using preconditioned skeletal muscle are necessary to assess the long-term effects of this technique.

The histological effects of cryocoagulation on the myocardium and coronary arteries.

The effects of epicardial and endocardial cryolesions were histologically studied in 29 dogs. To produce epicardial lesions, hypothermic exposure was applied at −60°C for 3 minutes, over or adjacent to the left anterior descending coronary artery. To produce endocardial lesions, exposure was applied at −60°C for 2 minutes, using the inflow occlusion technique over the ventricular septum. The dogs were killed 30 minutes to 6 months later. The cryolesions were sharply demarcated from the surrounding tissues and showed similar healing processes. The lesions showed no tendency to form aneurysms or rupture, although moderate intimal thickening of the coronary artery subjacent to the probe was observed. Our results indicate that cryocoagulation may greatly contribute to the surgical treatment of cardiac arrhythmias.

Reconstruction with free jejunal autograft after pharyngolaryngoesophagectomy

Twenty-four patients with hypopharyngeal or cervical esophageal carcinoma were treated surgically. All had squamous cell carcinoma, and none had intrathoracic lymph node involvement by preoperative computed tomography. Endoscopy in 18 patients confirmed there was no intramural spread into the thoracic esophagus. The patients underwent pharyngolaryngoesophagectomy and bilateral modified radical neck dissection. Reconstruction of the cervical esophagus was performed with transplantation of a free jejunal autograft. Postoperative complications included anastomotic leak in 2 patients (8.3%), wound infection in 3 (12.5%), and intussusception in 4 (16.7%). Reconstruction of the cervical esophagus was successful in 23 (95.8%) of the 24 patients. The operative mortality rate was 4.2%, and the 5-year survival rate was 39.7%. We emphasize that pharyngolaryngoesophagectomy followed by transplantation of a free jejunal graft is suitable for cervical esophageal carcinoma or hypopharyngeal carcinoma when the disease is limited to the cervical region.

Surgical treatment of arrhythmogenic right ventricular dysplasia: Long-term outcome

Eight male patients ranging from 15 to 51 years old (mean age, 36.3 years) underwent surgical treatment of ventricular tachycardia (VT) associated with arrhythmogenic right ventricular dysplasia. One patient had an associated left ventricular aneurysm. The earliest activation site was detected for 15 lesions, and delayed potentials were recorded during sinus rhythm in all patients. On the basis of the epicardial mapping, the origins of the VT foci in the right ventricle were resected. Cryoablation on the surrounding myocardium was performed. There were no surgical deaths or postoperative fatal complications. During long-term follow-up, there has been no recurrence of VT and no congestive heart failure in the 6 patients without left ventricular involvement. The 2 patients with LV involvement died late of either congestive heart failure or development of VT originating from the left ventricle. In conclusion, a surgical approach consisting of myocardial excision and cryocoagulation offers a curative treatment of VT associated with arrhythmogenic right ventricular dysplasia and yields excellent long-term results when the VT origin is well identified in the right ventricle.

Development of a new intraoperative radiofrequency ablation technique using a needle electrode

We studied a new intraoperative technique for radiofrequency ablation using a needle electrode. The ventricles of 12 mongrel dogs were ablated. The needle electrode was inserted to a depth of 3 mm through the epicardium. Macroscopically, tissue defect was found only at the needle insertion site. The degenerated area had a well-demarcated bullet shape with microscopical coagulation necrosis. This characteristic shape allows the ablation of deeper areas of the myocardium by deeper insertion of the ablation needle. Compared with conventional epicardial surface ablation, this new method could be used to achieve deeper coagulation. For any given energy level and conductance, the ratio between the volume and the depth of the lesion with this new method is smaller than that of lesions made by the conventional radiofrequency ablation method. With this new method, the energy spreads vertically, a characteristic suitable for deep ablation. This may result from the shape of the needle electrode itself. For ablation of deep targets, this new method is superior to the conventional approach because less myocardium is coagulated and the target can be ablated with greater efficiency, requiring the destruction of less tissue. In conclusion, the needle electrode procedure can achieve a narrower ablation for deeper targets than can the conventional technique.

Entrainment of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Tachycardia

In two patients with arrhythrnogenic right ventricular dysplasia (ARVDJ, sustained ventricular tachycardia (VT) was induced by programmed stimulations during serial drug testings. One patient had five and the other had two VT morphologies, and the sites of origin were determined by endocardial catheter mappings. When overdrive pacing was performed, constant fusion in the QflS complex was observed in the two patients. Constant fusion of a different degree was also observed at different paced cycle lengths. Both patients had dilated right ventricles and wall‐motion abnormality, and the diagnosis of ARVD was further confirmed by the specimen resected at the site of origin of VT. Therefore, VT in ARVD can be entrained and reentry is the most likely mechanism of such VT.

Thermally Controlled Laser Irradiation of the Myocardium with Intraoperative Ultrasound Monitoring

We used intraoperative ultrasonography (IOUS) to study the feasibility and safety of Nd:YAG laser irradiation of the myocardium in 26 canine left ventricular segments. During the laser irradiation process, the myocardial temperature was monitored and surface cooling was used. Afterward, intraoperative ultrasonographic scans, which enabled the evaluation of the irradiated lesions, were compared with cross sections made through the tissues. The total dose of laser energy ranged from 200 to 3,600 joules, and the estimated volume of irradiated lesions ranged from 76.8 to 2590 mm3. There were significant correlations between the laser discharge output (in joules [J]) and the irradiated lesion volume (P < 0.001), and between the laser energy density fin J/mm2) and the depth of the lesions (P < 0.01). Macroscopic examination of the cross sections of irradiated myocardium revealed that the lesions were well‐demarcated, but not charred or perforated. Thus, we could obtain a satisfactorily large zone of laser photocoagulation without inducing tissue damage, if surface cooling was used and the myocardial temperature was monitored. IOUS was successful in visualizing and locating the irradiated lesions that were seen as hypoechoic, clearly outlined nodules. We submit that this study has established the technical feasibility and dose‐response relationship of thermally controlled laser irradiation, and has demonstrated the usefulness of IOUS for the precise localization and monitoring of such laser treatment.