Mizuho Imamaki

Usefulness of intraoperative fluorescence imaging to evaluate local anatomy in hepatobiliary surgery.

BACKGROUND/PURPOSE One of the major complications encountered in hepatobiliary surgery is the incidence of bile duct and blood vessel injuries. It is sometimes difficult during surgery to evaluate the local anatomy corresponding to hepatic arteries and bile ducts. We investigated the potential utility of an infrared camera system as a tool for evaluating local anatomy during hepatobiliary surgery. METHODS An infrared camera system was used to detect indocyanine green fluorescence in vitro. We also employed this system for the intraoperative fluorescence imaging of the arteries and biliary system in a pig. Further, we evaluated blood flow in the hepatic artery, portal vein, and liver parenchyma during a human liver transplant and we investigated local anatomy in patients undergoing cholecystectomy. RESULTS Fluorescence confirmed that indocyanine green was distributed in serum and bile. In the pig study, we confirmed the fluorescence of the biliary system for more than 1 h. In the liver transplant recipient, blood flow in the hepatic artery and portal vein was confirmed around the anastomosis. In most of the patients undergoing cholecystectomy, fluorescence was observed in the gallbladder, cystic and common bile ducts, and hepatic and cystic arteries. CONCLUSIONS Intraoperative fluorescence imaging in hepatobiliary surgery facilitates better understanding of the anatomy of arteries, the portal vein, and bile ducts.

Application of Akaike information criterion to evaluate warfarin dosing algorithm

INTRODUCTION Several factors responsible for inter-individual differences in response to warfarin have been confirmed; however, unidentified factors appear to remain. The purpose of this study was to examine a simple method to evaluate whether optional variables are appropriate as factors to improve dosing algorithms. MATERIALS AND METHODS All patients were Japanese. Genotyping of selected genes was conducted, and other information was obtained from medical record. Dosing algorithms were constructed by multivariate linear regression analyses and were evaluated by the Akaike Information Criterion (AIC). RESULTS AND CONCLUSIONS Multivariate analysis showed that white blood-cell count (WBC), concomitant use of allopurinol, and CYP4F2 genotype are apparently involved in warfarin dose variation, in addition to well-known factors, such as age and VKORC1 genotype. We evaluated the adequacy of these variables as factors to improve the dosing algorithm using the AIC. Addition of WBC, allopurinol administration and CYP4F2 genotype to the basal algorithm resulted in decreased AIC, suggesting that these factor candidates may contribute to improving the prediction of warfarin maintenance dose. This study is the first to evaluate the warfarin dosing algorithm by AIC. To further improve the dosing algorithm, AIC may be a simple and useful tool to evaluate both the model itself and factors to be incorporated into the algorithm.

Retrograde Cerebral Perfusion with Hypothermic Blood Provides Efficient Protection of the Brain: A Neuropathological Study

Retrograde cerebral perfusion is a method that is recently being used for protection of the brain during operations on the aortic arch. This method is useful but is said to provide a limited time for protecting the brain. We designed an experiment in dogs to investigate neuropathologically the effect of protecting the brain for 120 minutes under: (1) circulatory arrest (CA); (2) retrograde cerebral perfusion with moderately cooled blood (RCPMC); and (3) retrograde cerebral perfusion with deeply cooled blood (RCPDC). We calculated the number of the abnormal cells of 400 hippocampal neurons per dog light microscopically. The number was 199 ± 23 (mean ± 1 SD) in the CA group, 149 ± 50 in the RCPMC group, and 72 ± 33 in the RCPDC group. The difference between the CA group and the RCPMC group was not statistically significant (p < 0.05), but there was a significant difference between the RCPMC and RCPDC groups (p < 0.05). The degree of cerebral protection provided by retrograde cerebral perfusion for 120 minutes is not sufficient when using moderately cooled blood. If we use deeply cooled blood at a temperature of about 10°C, we should obtain a sufficient degree of protection of the brain.

Mid-term results of surgery for chronic thromboembolic pulmonary hypertension

Pulmonary thromboendarterectomy is an effective surgical treatment for chronic thromboembolic pulmonary hypertension (CTEPH). In this study, we review our short- and mid-term results in the recent series of patients undergoing pulmonary thromboendarterectomy. Twenty-three patients (54+/-12 years) were re-evaluated 7-59 months (mean, 34 months) after surgery. Nine patients were in New York Heart Association functional class II, 11 patients in class III and three patients in class IV. All patients used supplemental oxygen therapy. After surgery, pulmonary hemodynamics were significantly improved: pulmonary vascular resistance (PVR) decreased from 925+/-342 to 337+/-260 dynes x s x cm(-5) (P<0.01); mean pulmonary artery pressure (MPAP) decreased from 47+/-12 to 25+/-10 mmHg (P<0.01). Three patients developed severe residual pulmonary hypertension and one of them died soon after surgery. During the follow-up period there were no deaths, but one recurrence of pulmonary embolism. Nineteen patients (86%) were in New York Heart Association functional class I or II and thirteen patients (59%) were weaned from oxygen therapy. In conclusion, pulmonary thromboendarterectomy provided remarkable early and late results with acceptable hospital mortality rate, normalization of pulmonary hemodynamics, and improvement in clinical functional status with relief of hypoxemia.

The effect of preoperative aspirin administration on postoperative level of von Willebrand factor in off-pump coronary artery bypass surgery

The effect of preoperative administration of aspirin on endothelial function in the patients undergoing off-pump coronary artery bypass (OPCAB) surgery is still unclear. Fifty consecutive patients undergoing OPCAB between May 2006 and May 2007 were equally divided into two groups — one without preoperative aspirin (group A; the first 25 patients) and the other with preoperative aspirin (group B; the next 25 patients). We investigated the degree of postoperative endothelial dysfunction by measuring the von Willebrand factor activity, which is a possible indicator of endothelial damage. The level of von Willebrand factor was not different between groups before surgery (group A 166% ± 53% vs group B 181% ± 62%; P = 0.39). Immediately after surgery it was significantly higher than before surgery in group A (231% ± 79%; rate of increase 1.24 ± 0.58), but not in group B (183% ± 77%; rate of increase 1.03 ± 0.55) (P < 0.02). The level was still significantly higher in group A than in group B on postoperative day 1 (group A 294 ± 66 vs 254 ± 51; P = 0.03), but there was no difference between groups on postoperative day 6. Although the frequency of blood transfusion was higher in group B, there was no difference in the amount of intraoperative bleeding between the groups. Preoperative use of aspirin before OPCAB could suppress the postoperative increase in von Willebrand factor, a possible indicator of endothelial damage, only in the early postoperative phase.

Pitfalls of skeletonized internal thoracic artery: comparison of graft kinking between skeletonized and pedicled grafts based on postoperative angiography findings.

Abstract  Background and aim of the study: Skeletonization of the internal thoracic artery (ITA) has several advantages: sequential bypass grafting can be easily performed, and a graft of increased length can make the distal coronary artery accessible. However, kinking of the grafts has been observed on postoperative angiograms in a few cases. We investigated whether there were significant differences in the frequency of graft kinking and stenosis degree at the kink site between pedicled and skeletonized grafts. Methods: Postoperative angiography was performed for all cases. In pedicled (n = 65) and skeletonized (n = 129) groups, the results of postoperative graft angiography were analyzed to investigate the presence of graft kinking and stenosis degree at the kink site. Results: Kinking was observed in 4 (5.9%) and 9 (3.9%) arteries in the pedicled and skeletonized groups, respectively (p = 0.341). The stenosis degree at the kink site (mean ± SD) was significantly higher in the skeletonized group (47.2 ± 16.8%) than in the pedicled group (23.5 ± 13.7%), (p = 0.032). In four patients in whom early postoperative angiography showed a kink with more than 50% stenosis, late‐term angiography was performed. All four cases showed regression of the stenosis degree at the kink site. Conclusions: When the ITA had a kink, the stenosis degree at the kink site was significantly higher in the skeletonized group than in the pedicled group. Late angiography often reveals regression of stenosis at the kink site. Immediate intervention need not always be performed if the patient has no angina caused by a stenotic lesion at the kink site.

Surgical Treatment for Chronic Pulmonary Thromboembolism Under Cardiopulmonary Bypass with Selective Cerebral Perfusion

Abstract The median sternotomy approach for the treatment of chronic pulmonary thromboembolism was recently improved by Daily, Jamieson, and coworkers who adopted it for use under cardiopulmonary bypass with intermittent circulatory arrest; however, we have sometimes found that the circulatory arrest time was too short to complete thromboendarterectomy. Therefore, we attempted to perform a selective cerebral perfusion technique to extend the endarterectomy time. Although we noted slight back-bleeding from the bronchial arteries, we were able to extend the endarterectomy time without causing any postoperative delirium. We conclude that the median sternotomy approach using cardiopulmonary bypass with selective cerebral perfusion may be the best option for extending the thromboendarterectomy time.

Heparin-Induced Thrombocytopenia After Coronary Artery Bypass Grafting with Cardiopulmonary Bypass: Report of a Case

A 79-year-old man was transferred to our hospital with severe chest pain and a suspected diagnosis of acute myocardial infarction. Emergency cardiac catheterization showed triple-vessel coronary artery disease, and we performed coronary artery bypass grafting under cardiopulmonary bypass (CPB). Continuous hemodiafiltration was started for acute renal failure postoperatively, and heparin was given as an anticoagulanting agent. By 9 days after the initiation of heparin therapy, his platelet count had fallen and a deep vein thrombosis had formed in his left leg. We suspected heparin-induced thrombocytopenia (HIT), and immediately discontinued the heparin, implementing danaparoid (Orgaran) instead, following which the platelet count recovered. Heparin-induced thrombocytopenia, which causes thrombosis, is a serious side effect of heparin therapy and few cases of HIT associated with CPB surgery have been reported in Japan.

Medium-term results after surgery for aortic arch aneurysm with hypothermic cerebral perfusion

We have used two techniques of hypothermic cerebral perfusion (CP) for the surgical treatment of aortic arch aneurysm in the last 10 years. Between March 1985 and December 1993, 83 patients underwent surgery for aortic arch aneurysm. Fifty-one cases had aortic dissection (AD) in the transverse arch and/or its branches, and 32 cases showed true aneurysm (TA) of the aortic arch. In those 83 patients, 37 cases received antegrade CP and 46 cases underwent retrograde CP. Surgical results were compared among the groups by Kaplan-Meier actuarial method and Cox-Mantel statistical analysis. The early mortality after surgery for aortic arch aneurysm was 11.8% in the AD group and 21.9% in the TA group. The early mortality was 21.6% with antegrade CP and 10.9% with retrograde CP. The 6-year actuarial survival rate was 71.7% in the TA group and 67.1% in the AD group. In the AD group, the 3-year survival rate was 93.9% with retrograde CP and 61.1% with antegrade CP (P < 0.005). In the TA group, the 3-year survival rate was similar for antegrade CP (73.3%) and retrograde CP (69.2%). These results suggest that current surgical results of aortic arch aneurysm with hypothermic CP are acceptable and the retrograde CP technique might be recommended, especially for surgery of aortic arch aneurysm with AD.

Efficacy of Elective Intra-aortic Balloon Pump Therapy for High-Risk Off-Pump Coronary Artery Bypass: A Prospective Comparative Study

OBJECTIVE This study evaluated the usefulness of elective intra-aortic balloon pumping (IABP) in high-risk off-pump coronary artery bypass grafting (OPCAB). MATERIALS AND METHODS From October 2002 through September 2006, total of 143 patients were operated with OPCAB. These patients were divided into two groups and clinical outcomes were compared: Group E (N = 30): Elective IABP group and Group C (N = 113): Control group, OPCAB without IABP. The criteria of elective application of IABP were severe stenosis of left main coronary artery (LMCA) or left ventricular dysfunction with an ejection fraction of less than 35%. RESULTS No significant difference was noted in the duration of ICU stay (Group E: 1.13 ± 0.43 days; Group C: 1.18 ± 0.60 days, p = 0.710), the number of patients on a respirator for 24 hours or longer after surgery (Group E: 10.0%; Group C: 5.3%, p = 0.397), hospital mortality (Group E: 0%; Group C: 0%), or the frequency of postoperative major complications between two groups. CONCLUSIONS The outcomes of OPCAB using elective IABP in high-risk patients, such as those with severe LMCA stenosis or left ventricular dysfunction, were similar to those of OPCAB in low-risk patients, suggesting the usefulness of elective IABP in OPCAB.