Tatsuya Kurosaki

Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease

OBJECTIVES Spinal cord injury (SCI) after the frozen elephant trunk (FET) technique is more frequent than after endovascular aneurysm repair. This study aimed to identify risk factors of SCI after the FET technique. METHODS We performed the FET technique for extended thoracic aortic disease in 224 patients (mean age, 72.1 ± 10.9 years) from September 1997 to December 2011. The patients included those with acute type A aortic dissection (n = 103), acute type B aortic dissection (n = 30), chronic type B aortic dissection (n = 11) and thoracic atherosclerotic aneurysm (n = 80). Cerebrospinal fluid drainage (CSFD) was preoperatively performed for 18 elective cases with a high risk of spinal cord ischaemia from January 2003. RESULTS Postoperative SCI was present in 8 (3.5%), including complete paraplegia in 3, patients and transient or permanent paraparesis in 5 patients. CSFD was not a significant independent risk factor (P = 0.93) for SCI. Univariate logistic regression analysis identified pathology (P = 0.001), diabetes (P = 0.001), previous aortic operation (P = 0.003), atherosclerotic aorta (P = 0.003), distal position of the stent graft below the ninth thoracic vertebral level (Th9; P = 0.001) and low blood pressure after the operation (P = 0.009) as significant independent risk factors for SCI. Stepwise logistic regression analysis identified the distal position of the stent graft below Th9 (P = 0.003; odds ratio [OR], 15.167; 95% confidence interval [95% CI], 2.568-89.578), mean pressure <70 mmHg (P = 0.008; OR, 11.470; 95% CI, 1.920-68.546) and diabetes (P = 0.009; OR, 9.621; 95% CI, 1.779-52.032) as significant independent risk factors for SCI. CONCLUSIONS There were multiple factors predicting the risk of SCI after the FET technique. Paraplegia may be prevented by avoiding deep insertion of the stent graft and by keeping blood pressure elevated after the operation.

Late Occurrence of Atrial Arrhythmias After the Simple Left Atrial Procedure for Chronic Atrial Fibrillation in Mitral Valve Surgery

BACKGROUND We postulated that chronic atrial fibrillation (AF) associated with mitral valve disease originated from the distended left atrium and is maintained by itself. We had performed a simple left atrial procedure for the elimination of chronic AF associated with mitral valve disease in patients from 1993 to 1998. This paper evaluated the long-term results of the simple left atrial procedure after more than 10 years, and discussed the late occurrence of atrial arrhythmias in relation to the left atrial procedure. METHODS Fifty-two patients were examined after the simple left atrial procedure concomitant with mitral valve surgery retrospectively. We divided the patients into two groups with or without the elimination of AF (AF group and non-AF group). The disappearance of AF was estimated by electrocardiography, and atrial function was estimated by transthoracic echocardiography. The elimination of chronic AF and the recovery of atrial systolic function after surgery were evaluated during more than 10 years of follow-up. RESULTS In a total of 702.5 patient-years of follow-up (range, 11.3 to 16.1 years; mean, 13.5 ± 3.5 years), AF disappeared in 73% of the patients (38 of 52) at 5 years and in 69% of the patients (36 of 52) at 10 years after the simple left atrial procedure. Among the preoperative and intraoperative variables, a long duration of AF was the only predictive factor for late recurrences of AF (p < 0.05). In the sinus rhythm group, 2 of 36 patients remained in left atrial tachycardia. The final success rate in elimination of AF and atrial tachycardia was 34 of 52 patients (65.3%) at 10 years. An atrial kick was detected in 60% of patients across the mitral valve and in 100% of patients across the tricuspid valve by transthoracic echocardiography. CONCLUSIONS The simple left atrial procedure could terminate chronic AF associated with mitral valve disease and maintain sinus rhythm for more than 10 years in 65% of chronic AF patients. Left atrial tachycardia was a troublesome complication after cryoablation toward mitral valvular annulus. This study shows the long-term results and problems of the simple left atrial procedure for more than 10 years of follow-up.

Analysis of Flow Patterns in a Ventricular Assist Device: A Comparative Study of Particle Image Velocimetry and Computational Fluid Dynamics

In order to develop a diaphragm-type ventricular assist device (VAD), we studied the flow field change following structural modifications. We devised a center flow-type pump by putting a small projection on the center of the housing and/or diaphragm to provide a center in the flow field, and examined the following four types of VADs: N type without a projection, D type with a projection on the diaphragm, H type with a projection on the housing, and DH type with projections on both the diaphragm and housing. Computational fluid dynamics (CFD) was used for flow simulation. Particle image velocimetry (PIV) was also used to verify the reliability of the CFD method and to determine how the flow field changes in the presence of a projection. The results of the PIV and CFD analyses were comparable. The placement of a projection on the housing was most effective in rectifying the flow field.

An educational training simulator for advanced perfusion techniques using a high-fidelity virtual patient model.

The operation of cardiopulmonary bypass procedure requires an advanced skill in both physiological and mechanical knowledge. We developed a virtual patient simulator system using a numerical cardiovascular regulation model to manage perfusion crisis. This article evaluates the ability of the new simulator to prevent perfusion crisis. It combined short-term baroreflex regulation of venous capacity, vascular resistance, heart rate, time-varying elastance of the heart, and plasma-refilling with a simple lumped parameter model of the cardiovascular system. The combination of parameters related to baroreflex regulation was calculated using clinical hemodynamic data. We examined the effect of differences in autonomous-nerve control parameter settings on changes in blood volume and hemodynamic parameters and determined the influence of the model on operation of the control arterial line flow and blood volume during the initiation and weaning from cardiopulmonary bypass. Typical blood pressure (BP) changes (hypertension, stable, and hypotension) were reproducible using a combination of four control parameters that can be estimated from changes in patient physiology, BP, and blood volume. This simulation model is a useful educational tool to learn the recognition and management skills of extracorporeal circulation. Identification method for control parameter can be applied for diagnosis of heart failure.

Efficacy of Cardiopulmonary Rehabilitation With Adaptive Servo-Ventilation in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

BACKGROUND Postoperative complications after cardiac surgery increase mortality. This study aimed to evaluate the efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation (ASV) in patients undergoing off-pump coronary artery bypass grafting (OPCAB). METHODS AND RESULTS A total of 66 patients undergoing OPCAB were enrolled and divided into 2 groups according to the use of ASV (ASV group, 30 patients; non-ASV group, 36 patients). During the perioperative period, all patients undertook cardiopulmonary rehabilitation. ASV was used from postoperative day (POD) 1 to POD5. Hemodynamics showed a different pattern in the 2 groups. Blood pressure (BP) on POD6 in the ASV group was significantly lower than that in the non-ASV group (systolic BP, 112.9±12.6 vs. 126.2±15.8 mmHg, P=0.0006; diastolic BP, 62.3±9.1 vs. 67.6±9.3 mmHg, P=0.0277). The incidence of postoperative atrial fibrillation (POAF) was lower in the ASV group than in the non-ASV group (10% vs. 33%, P=0.0377). The duration of oxygen inhalation in the ASV group was significantly shorter than that in the non-ASV group (5.1±2.2 vs. 7.6±6.0 days, P=0.0238). The duration of postoperative hospitalization was significantly shorter in the ASV group than in the non-ASV group (23.5±6.6 vs. 29.0±13.1 days, P=0.0392). CONCLUSIONS Cardiopulmonary rehabilitation with ASV after OPCAB reduces both POAF occurrence and the duration of hospitalization.

Treatment Strategy for Acute Type A Aortic Dissection Complicated with Organ Ischemia

OBJECTIVE We report our current treatment strategy for acute type A aortic dissection with organ ischemia as well as notable findings in our experience. MATERIALS AND METHODS Among 101 cases of acute type A aortic dissection, 25 had organ ischemia. Malperfusion was assessed at the aorta, proximal portion of the branch, organ parenchyma, and organ function by means of multiple modalities, including transesophageal echocardiography (TEE), near-infrared spectroscopy, and physical examinations. It was assessed every time the perfusion status was altered. RESULTS There were three operative deaths and one late hospital death. Uncertainty of symptoms and inadequate preoperative assessment in an emergent situation indicated the necessity of an overall check-up of organ ischemia in the operating room on a routine basis. Multi-modality assessment including TEE was helpful for this purpose. Two cases indicated that recovery of a true lumen could be inadequate despite true lumen perfusion including central cannulation. Thrombus in the false lumen appeared to be responsible. CONCLUSIONS To solve practical problems in treating acute type A dissection with organ ischemia, real-time information on organ perfusion is important for detecting the presence of malperfusion, making an appropriate strategy, and immediately assuring the efficacy of the means taken.

Everted leaflet of a bovine pericardial aortic valve.

We report on an everted leaflet of a Carpentier-Edwards Perimount (CEP) valve in an aortic position. A 71-year-old female patient with aortic regurgitation underwent valve replacement with a 21-mm CEP valve. After aortic declamping, transesophageal echocardiography (TEE) revealed significant transvalvular regurgitation due to an immobilized non-coronary leaflet. Upon re-aortotomy, we found an everted leaflet without any structural damage to the valve. It was readily corrected and eversion did not recur spontaneously. The valve was not replaced because it had no intrinsic problems, eversion was unlikely to be induced by cardiac output, and there was no evidence that re-implantation would avoid further problems. Her postoperative course was uneventful without recurrence of aortic regurgitation during three months of follow-up after surgery. On TEE measurements, allocation of stent posts was slightly uneven. Since leaflet eversion was re-created by distortion of the stent in an ex-vivo model, a mild imbalance of sutures might increase the risk of this event. TEE was beneficial for detection, decision-making, and avoidance of an early reoperation. This case indicates that reimplantation or replacement of the valve is not always necessary for an everted valve leaflet. Although the patient has had an uneventful course thus far, careful follow-up is mandatory.

Mid-term results of the box pulmonary vein isolation and the cryo-maze procedure for chronic atrial fibrillation associated with mitral valve disease

PurposeWe performed box pulmonary vein isolation and the modified Maze procedure using cryoablation (cryo-maze) to eliminate chronic atrial fibrillation (AF) associated with mitral valve disease from 1999 to 2004. This article compares the elimination rate of chronic AF and the postoperative occurrence of new atrial tachycardia after both procedures over a follow-up period of >5 years.MethodsA total of 75 patients were enrolled in the study. Among them, 40 patients underwent box pulmonary vein isolation for chronic AF concomitant with solitary mitral valve surgery. Another 35 patients underwent the cryo-maze procedure for chronic AF concomitantly with both mitral and tricuspid valve surgeries. We evaluated the postoperative AF elimination rate and the occurrence of atrial tachycardia.ResultsDuring a total of 622.5 patient-years of followup, AF disappeared in 26 of 40 (65%) patients after the box pulmonary vein isolation and in 26 of 35 (74%) patients after the cryo-maze procedure at 5 years. Common atrial flutter occurred in 2 of 40 (5.0%) patients after the pulmonary vein isolation procedure. Left atrial Received: 8 December 2010 / Accepted: 20 April 2011

Three-dimensional CT Venography: A Diagnostic Modality for the Preoperative Assessment of Patients with Varicose Veins

OBJECTIVE We preoperatively assessed varicose veins by means of computed tomography (CT) with contrast injection in the veins of the lower extremity (CT venography). This paper reports the procedures, results and implications of CT venography from the surgical aspect. METHODS A total of 48 legs in 39 patients were examined. Contrast medium was diluted ten-fold and injected into the lower extremity veins, often using a dual route of injection. The images were reconstructed with the volume-rendering method. RESULTS CT venography clearly visualized the veins with a small amount of contrast medium and facilitated the identification of anatomy that was not suitable for passing the stripper. In addition, CT venography helped identify unusual types of varicose veins or uncommon sites of inflow of small saphenous veins. Such information was helpful for avoiding unexpected vascular injury or for minimizing skin incision. Dual-route injection was beneficial to minimize the blind zones. Doppler ultrasound could be more focused on hemodynamic assessment and determination of incision sites. CONCLUSIONS CT Venography is feasible in all cases of varicose veins. When performed in conjunction with ultrasonography, it appears to facilitate the safe and efficient treatment of various types of varicose veins.

A novel measurement and delivery system for synchronizing oxygen gas flow with blood flow during cardiopulmonary bypass

Monitoring the blood pump and the oxygen gas flow meter are important maneuvers at the initiation of cardiopulmonary bypass (CPB). We present a novel system, designed to improve safety in the heart-lung machine by linking the control of blood flow and the oxygen gas flow meter. This system uses a mass flow controller to provide and control oxygen flow based on the ventilation-perfusion (V/Q) ratio, using the electronic signal of the blood flow. We tested the system, in vitro and in vivo, and examined the resulting level of blood oxygenation. When extracorporeal circulation was initiated, the oxygen flow was instantly linked to the circulating blood flow, providing an adequate V/Q ratio; the partial pressure of oxygen in the blood was maintained at a normal level. Although we have yet to confirm the safety of this system in clinical trials, the new safety assist device can automatically supply oxygen to the oxygenator at the beginning of CPB.