Masahito Minakawa

Injectable hydrogel properties influence infarct expansion and extent of postinfarction left ventricular remodeling in an ovine model

A recent trend has emerged that involves myocardial injection of biomaterials, containing cells or acellular, following myocardial infarction (MI) to influence the remodeling response through both biological and mechanical effects. Despite the number of different materials injected in these approaches, there has been little investigation into the importance of material properties on therapeutic outcomes. This work focuses on the investigation of injectable hyaluronic acid (MeHA) hydrogels that have tunable mechanics and gelation behavior. Specifically, two MeHA formulations that exhibit similar degradation and tissue distribution upon injection but have differential moduli (~8 versus ~43 kPa) were injected into a clinically relevant ovine MI model to evaluate the associated salutary effect of intramyocardial hydrogel injection on the remodeling response based on hydrogel mechanics. Treatment with both hydrogels significantly increased the wall thickness in the apex and basilar infarct regions compared with the control infarct. However, only the higher-modulus (MeHA High) treatment group had a statistically smaller infarct area compared with the control infarct group. Moreover, reductions in normalized end-diastolic and end-systolic volumes were observed for the MeHA High group. This group also tended to have better functional outcomes (cardiac output and ejection fraction) than the low-modulus (MeHA Low) and control infarct groups. This study provides fundamental information that can be used in the rational design of therapeutic materials for treatment of MI.

Improved Outcome of Surgical Pulmonary Embolectomy by Aggressive Intervention for Critically Ill Patients

BACKGROUND Acute massive pulmonary thromboembolism is a life-threatening disorder, and prompt treatment is necessary. We analyzed the outcome of pulmonary embolectomy for massive pulmonary embolism. METHODS Nineteen patients who underwent pulmonary embolectomy were retrospectively investigated. Average age of patients was 59 years, and 79% were female. Most patients had massive or submassive pulmonary thromboemboli dislodging into the main pulmonary trunk or bilateral main pulmonary arteries. Hemodynamics of most patients were unstable. Two patients required percutaneous cardiopulmonary support before embolectomy, and 4 required cardiopulmonary resuscitation. In 6 patients, thrombolysis was ineffective. RESULTS All patients underwent emergent pulmonary embolectomy. Operative mortality was 5.3%. No patients exhibited newly developed neurologic damage. Ten-year survival rate was 83.5% ± 8.7%. CONCLUSIONS Pulmonary embolectomy saves critically ill patients having acute massive pulmonary thromboembolism. We must evaluate pulmonary embolism patients with an algorithm that includes surgical embolectomy as one of several therapeutic options.

Left atrial maze procedure: A useful addition to other corrective operations

BACKGROUND The left atrial maze procedure is performed to treat atrial fibrillation (AF), mainly in patients with mitral valve disease. In this study, we assessed the midterm results of this procedure and clinically analyzed predicting factors for postoperative persistent AF. METHODS From June 1997 to May 2001, the left atrial maze procedure was performed on 31 patients (29 with mitral valve disease and 2 lone AF). For purposes of analysis, patients were divided postoperatively into those with persistent atrial fibrillation (AF) and those with sinus rhythm (SR), except 2 patients who required pacemaker implantation for sinus node dysfunction. Over a follow-up period of more than 12 months, patients were compared based on their preoperative and intraoperative variables. RESULTS At discharge, the success rate was 89.7%. The midterm rates (total of 94.9 patient-years of follow-up) of sinus rhythm and freedom from AF were 72.4% and 79.3%, respectively. There were significant differences in duration of AF, voltage of f-wave at first precordial lead of electrocardiogram, and cardiothoracic ratio between the SR and AF groups. CONCLUSIONS Our midterm results suggest that the left atrial maze procedure is an effective alternative adjunct procedure for elective open heart surgery to treat AF, depending upon the patients clinical condition.

Early and long-term outcome of total arch replacement using selective cerebral perfusion.

BACKGROUND The aim of this study was to analyze mortality and morbidity of patients undergoing total arch replacement. METHODS We analyzed data from 122 patients who underwent total arch replacement. Total arch replacement was performed using selective cerebral perfusion, with an open distal anastomosis using a trifurcated coated graft. Univariate and multivariate analysis were performed concerning postoperative neurologic dysfunction and early mortality. Long-term mortality was estimated by the Kaplan-Meier method. RESULTS Permanent and temporary neurologic dysfunction were 4.1% (5 cases) and 5.7% (7 cases), respectively. Hospital mortality was 8.2% (10 cases). There was no significant difference in hospital mortality or neurologic dysfunction between the two groups divided by age less than or greater than 70 years old, emergency versus elective surgery, and dissection versus true aneurysm. After multivariate analysis, independent predictors for hospital mortality were found to be infection, operation time longer than 10 hours, and EuroSCORE greater than 15; whereas those for neurologic dysfunction were operation time longer than 10 hours and ischemic heart disease. Overall long-term survival was 80.4% at 5 years and 58.9% at 10 years. CONCLUSIONS The early and long-term outcomes of total arch replacement using selective cerebral perfusion and appropriate establishment of cardiopulmonary bypass were satisfactory.

Emergency Pulmonary Embolectomy During the Second Trimester of Pregnancy: Report of a Case

We report a case of acute massive pulmonary thromboembolism, which occurred during the second trimester of pregnancy in a 35-year-old woman with thrombocytopenia and anemia secondary to myelodysplastic syndrome. We performed successful emergency pulmonary embolectomy, under cardiopulmonary bypass, using argatroban as an anticoagulant. An intra-aortic balloon pump was used to maintain placental blood flow. The patient recovered completely and was later delivered of a healthy baby. Thus, pulmonary embolectomy saved both the mother and the fetus.

Prevalence of venous thromboembolism in neurosurgical patients

This study was conducted to clarify the prevalence of venous thromboembolism (VTE) in neurosurgical patients. Prospective study for venous thromboembolism screening after neurosurgery was conducted. Thirty-seven patients were screened by ultrasonography for deep vein thrombosis in the lower extremities at an average of 12 days postoperatively. All patients received standard thromboprophylaxis using graded compression stocking with/without intermittent pneumatic compression following the VTE prevention guidelines. Definitive diagnosis of venous thromboembolism was made by contrast-enhanced whole-body computed tomography. Prevalence of deep vein thrombosis of the lower legs was 13.5% (5/37). Incidence of pulmonary embolism was 60% (3/5) in patients having deep vein thrombosis. All patients having venous thromboembolism were asymptomatic. In high-risk patients, VTE prevalence after neurosurgery was high even under mechanical prophylaxis. Additional pharmacological prophylaxis should be considered for patients with high risk of VTE.

Hydrodynamic evaluation of axillary artery perfusion for normal and diseased aorta

Axillary artery perfusion is an attractive alternative to reduce the frequency of atheroembolism in extensive atherosclerotic aorta and aortic aneurysms. This study was conducted to evaluate the flow dynamics of axillary artery perfusion. Transparent glass models of a normal aortic arch and an aortic arch aneurysm were used to evaluate hydrodynamic properties. Streamline analysis and distribution of the shear stress was evaluated using a particle image velocity method. In the normal aortic arch model, rapid flow of 80 cm/s from the right axillary artery ran out from the brachiocephalic artery and grazed the lesser curvature of the aortic arch. There was secondary reversed flow in the ascending aorta. Flow from left axillary perfusion went straight to the descending aorta. In the aortic arch aneurysm model, flow from both axillary arteries hit the lesser curvature of the aortic arch and went into the ascending aorta with vortical flow. Distribution of shear stress was high along the jet from the ostium of the brachiocephalic artery and left subclavian artery. Flow in the aortic arch and the ascending aorta was unexpectedly rapid. Special care must be taken when the patient has frail atheroma around arch vessels or the lesser curvature of the aortic arch during axillary artery perfusion.

Poly-2-methoxyethylacrylate-coated bypass circuits reduce activation of coagulation system and inflammatory response in congenital cardiac surgery

Surface-coated cardiopulmonary bypass (CPB) has been shown to have excellent biocompatibility during cardiac surgery in adults, but there have been only a few reports demonstrating the efficacy of this coating for congenital cardiac surgery. We tested the efficacy of poly-2-methoxyethylacrylate (PMEA) coating for CPB circuits in congenital cardiac surgery. Eleven operative cases of ventricular septal defect were studied: group C (control: no coating, n = 5) and group P (PMEA coating, n = 6). The platelet count and β-thromboglobulin (βTG), fibrinogen (FBG), thrombin-antithrombin complex (TAT), and neutrophil elastase levels were measured during the operation. Postoperative chest tube drainage was analyzed and the surface of the artificial lung was observed with an electron microscope. Elevation of TAT and neutrophil elastase was suppressed in group P (P < 0.05). Observation of the artificial lung surface using an electron microscope clearly revealed fewer blood cells were adherent to the surface in group P. The FBG level and postoperative bleeding were relatively lower in group P, but there were no significant differences between groups. The platelet count and βTG level were the same in both groups. We concluded that the PMEA-coated circuit reduces activation of the coagulation system and the inflammatory reaction in pediatric cardiac surgery.

Infective endocarditis with cerebrovascular complications: timing of surgical intervention

Management of infective endocarditis (IE) with cerebrovascular complications is difficult due to absence of concrete evidence. These patients usually have multiple neurological deficits and the optimal timing for cardiac operation remains controversial. The aims of this study were to present cases and discuss the treatment options for IE with cerebrovascular complications. From 1998 to 2010, 51 patients underwent operations for IE at our institution. From a review of medical records, 10 patients (19.6%) with preoperative neurological complications were identified. Data on these 10 patients were analysed. Cerebrovascular complications included cerebral infarction (n = 4, 40.0%), mycotic aneurysm (n = 1, 10.0%), mycotic aneurysm plus cerebral infarction (n = 3, 30.0%), meningitis (n = 1, 10.0%) and mycotic aneurysm with cerebral haemorrhage plus meningitis (n = 1, 10.0%). Of 5 patients having mycotic aneurysms, 3 underwent clipping before cardiac operations. The mean interval from craniotomy to cardiac operations was 26.7 ± 21.8 days. A cardiac operation was performed initially on seven patients. The mean interval from the onset of neurological deficit to cardiac operation was 7.4 ± 9.8 days. The mortality rate was 10.0%. Postoperative deterioration was not observed. Management of IE with cerebrovascular complications should be based on case-by-case multidisciplinary assessment of potential risks and benefits of intracranial and cardiac operations.

Olmesartan improves left ventricular function in pressure-overload hypertrophied rat heart by blocking angiotensin II receptor with synergic effects of upregulation of angiotensin converting enzyme 2

It is not clear how the blocking effect of angiotensin II receptors by olmesartan affects the functional recovery of pressure-overload hypertrophied heart. Hypertrophied heart was created by abdominal aortic banding above the celiac artery in Wistar rats at the age of eight weeks. Hypertrophied heart was excised and studied at 10 and 16 weeks after the operation (HT groups). For the last four weeks before the experiment, olmesartan (0.2 mg/kg per day) was administered subcutaneously by osmotic minipumps (Olm groups). Left ventricular function was measured by Langendorff perfusion. The levels of mRNA for angiotensin-converting enzyme (ACE), ACE2 and extracellular signal-regulated kinases (ERKs) in myocardium were analyzed by RT-PCR. Left ventricular systolic (+dP/dtmax, left ventricular systolic pressure) and diastolic functions (-dP/dtmax, tau) were impaired in HT groups, while in Olm groups they were significantly improved. The left ventricle to body weight (LV/BW) ratio increased significantly in HT groups, but in Olm groups the LV/BW ratio decreased significantly in comparison with HT groups. The ACE2 mRNA level was significantly higher in Olm groups as compared with HT groups. Plasma angiotensin II and the ERK mRNA level in HT groups increased significantly, but decreased in Olm groups in comparison with HT groups significantly. Olmesartan improved left ventricular function and hypertrophy through the increase of the ACE2 mRNA and decrease of both angiotensin II and ERK mRNA in pressure-overload rat heart.