The long-term outcomes of partial arch repair using the frozen elephant trunk technique for distal arch aortic aneurysm.

PURPOSE: The purpose of this study was to evaluate the long-term results of partial arch repair using the frozen elephant trunk (FET) technique for distal arch aortic aneurysm and to examine the late complications. METHODS: Thirty-eight patients with true distal arch aortic aneurysms were repaired with FET introduced through an incision in the proximal arch aorta. Follow-up computed tomography was performed every 6 or 12 months in 36 surviving patients. The maximum dimension of the excluded aneurysmal space was measured to determine whether the aneurysmal space had decreased or disappeared. Late complications were also evaluated during the long-term follow-up. RESULTS: There was 1 hospital death (2.6%) and 1 (2.6%) case of paraplegia. There were 2 late sudden deaths (5.2%) thought to be due to aneurysm rupture and arrhythmia. Postoperative serial-computed tomography showed shrinkage of the excluded aneurysmal space in 33 of 36 patients. Late aneurysmal formation occurred in the anastomotic site in three patients. One patient underwent thoracic endovascular stent grafting 10 years after surgery, 1 patient had total arch replacement 9 years after surgery, and 1 died due to rupture. CONCLUSION: Frozen elephant trunk was found to be a useful alternative for treating true distal arch aortic aneurysm. However, we must be alert for late aneurysmal formation at the incision site.

Abdominal organ protection strategy for aortic arch aneurysm surgery.

INTRODUCTION: Body temperature maintained during open distal anastomosis in patients who undergo aortic surgery has been showing an upward trend; however, a higher temperature may increase visceral organ and spinal cord injury. Distal perfusion may reduce abdominal organ injury, especially acute kidney injury (AKI). METHODS: From 2009 to 2016, 56 patients who underwent ascending aortic and/or aortic arch surgery were enrolled. Open distal anastomosis was performed using one of three protection strategies: 1) systemic temperature of 25°C followed by selective cerebral perfusion (SCP) with lower body circulatory arrest (Group CA25, n=27); 2) systemic temperature of 28°C followed by SCP with lower body circulatory arrest (Group CA28, n=4); and 3) systemic temperature of 28°C followed by SCP with distal aortic perfusion (Group DP, n=25). RESULTS: During the postoperative course, levels of blood urea nitrogen, creatinine, liver enzymes, lactate dehydrogenase and lactate in Groups CA28 and CA25 were significantly higher than those in Group DP. AKI defined by the AKI Network occurred in 28 cases (50%) and 3 cases required permanent hemodialysis. AKI was significantly higher in Groups CA25 and CA28 than in Group DP (p=0.026). Mid-term follow-up showed that patients who developed postoperative AKI were more likely to suffer from cardiovascular events. CONCLUSIONS: Distal perfusion during open distal anastomosis reduced kidney and liver injury after thoracic aortic surgery despite an increased body temperature of up to 28°C. This strategy may be useful to prevent AKI, liver dysfunction, the need for hemodialysis and multiple organ failure and could improve mid-term results.

Preoperative Tissue Doppler Imaging-Derived Atrial Conduction Time Predicts Postoperative Atrial Fibrillation in Patients Undergoing Mitral Valve Surgery for Mitral Valve Regurgitation.

BACKGROUND: Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery and may result in stroke, heart failure and poor prognosis. This study evaluated a novel index of total atrial conduction time derived from the P-wave onset (lead II) to the peak A' wave on tissue Doppler imaging (PA-TDI duration) in patients undergoing mitral valve surgery (MVS) for mitral valve regurgitation. METHODS AND RESULTS: Seventy-three patients undergoing MVS had transthoracic echocardiography with tissue Doppler imaging preoperatively and were monitored postoperatively with continuous electrocardiographic telemetry for 14 days. Preoperative characteristics, echocardiographic data, operative data and postoperative findings were compared between patients with (n=44) and without (n=29) POAF. Postoperative cardiac events were higher in patients with than without POAF (12/44, 27% vs. 3/29, 10%; P=0.0798) and cerebral events occurred in only 2 POAF patients. On multivariate analysis the independent predictors of POAF were degenerative disease etiology (OR, 4.61; 95% CI: 1.41-15.0; P=0.0112) and PA-TDI duration (OR, 1.04; 95% CI: 1.01-1.07; P=0.0048). On ROC curve analysis a PA-TDI cut-off of 159.4 ms was optimal for predicting POAF. CONCLUSIONS: PA-TDI duration was an independent predictor of POAF after MVS. Patients with PA-TDI duration >159.4 ms should be considered high risk and treated appropriately to improve outcome.

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.

Preoperative tissue Doppler imaging-derived atrial conduction time can predict postoperative atrial fibrillation in patients undergoing aortic valve replacement for aortic valve stenosis.

BACKGROUND: Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery and may result in stroke or heart failure and poor prognosis. This study aimed to evaluate a novel index of total atrial conduction time derived from the P-wave onset (lead II) to the peak A' wave on tissue Doppler imaging (PA-TDI duration). The PA-TDI duration was compared with previously reported predictors of POAF, and the optimal cutoff value of PA-DTI was calculated in patients undergoing aortic valve replacement (AVR) for AV stenosis (AS). METHODS AND RESULTS: We enrolled 63 patients undergoing isolated AVR. They underwent transthoracic echocardiography with TDI preoperatively and were monitored postoperatively with continuous electrocardiographic telemetry for 7 days. The hospital stay was significantly longer in the 41 patients with POAF than in the 22 without POAF (33.8±19.7 vs. 24.1±8.1 days, P=0.03). Multivariate analysis revealed that PA-TDI duration (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.02-1.13; P=0.0072) and age (OR, 1.14; CI, 1.03-1.28; P=0.016) were significant independent predictors of POAF. Receiver-operating characteristic curve analysis showed the optimal cutoff values of PA-TDI duration and age were 147.3 ms and 74 years, respectively. CONCLUSIONS: The PA-TDI duration was an independent predictor of POAF after AVR for AS. Patients with PA-TDI duration >147 ms should be considered high risk and treated appropriately to improve outcomes.

Modified septal myectomy using a curved knife for left ventricular septal hypertrophy.

An 86-year-old woman presented with chest pain and discomfort. Echocardiography revealed severe aortic valve stenosis and asymmetric septal hypertrophy. Aortic valve replacement and myectomy were performed using a curved knife. The blade was U-shaped in cross-section, and was curved upward along the long axis. Hypertrophic septal myocardium was removed along the long axis of the left ventricle (LV), and a groove for blood flow was constructed. The patient was discharged uneventfully without recurrence of her chest discomfort. Our result suggested that a curved knife is a reasonable option for transaortic septal myectomy in patients with obstructive LV hypertrophy.

A case of Heyde syndrome: resolution following aortic valve replacement.

Heyde syndrome is a triad of aortic stenosis, acquired coagulopathy, and anemia due to bleeding from intestinal angiodysplasia. Here we describe a case of this syndrome. An 80-year-old woman with severe aortic stenosis was referred to our department for an aortic valve replacement. She suffered from recurrent iron-deficiency anemia and required transfusions every 2 weeks. Gastroscopy and colonoscopy were normal with the exception of angiodysplasia without bleeding in the cecum. After aortic valve replacement her anemia was resolved. She was discharged on postoperative day 22. No transfusions were needed after the procedure. To date, her hemoglobin has remained stable at >10 mg/dL.

Epicardial atrial mapping can predict elimination of chronic atrial fibrillation after the box pulmonary vein isolation during mitral valve surgery.

BACKGROUND: The pulmonary veins (PV) and posterior left atrium (LA) may contribute to the occurrence and maintenance of atrial fibrillation (AF). We evaluated whether simple epicardial electrophysiological mapping can predict elimination of chronic AF after the box PV isolation procedure. METHODS AND RESULTS: Using a computerized 48-channel mapping system, we performed intraoperative atrial mapping in 16 patients with chronic AF associated with mitral valve (MV) disease. Patients' ages ranged from 48 to 76 years (mean, 61.4 years). AF duration ranged from 1 to 16 years (mean, 7.5±5.4 years). Simple box PV isolation was performed during the MV operation. Regular and repetitive activation was found in the LA of 12 of 16 patients, and irregular and chaotic activation was found in both atria in 4 of 16 patients; 12 patients with regular and repetitive activation of the LA were treated by box PV isolation and the other 4 patients with irregular and chaotic activation in both atria did not recover sinus rhythm after this procedure. AF-free rate was significantly higher in patients with regular and repetitive activation of the LA (P<0.01). CONCLUSIONS: Box PV isolation was effective in the treatment of chronic AF associated with MV disease. Epicardial atrial mapping may predict elimination of AF after the box PV isolation.

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.

Evaluation of basic perfusion techniques, ECCSIM-Lite simulator.

Although serious accidents during extracorporeal circulation are infrequent, potential adverse events with both equipment and operation do still occur and require immediate and well-coordinated responses. Hence, perfusionists need to be well trained in both standard and emergency procedures, and this would be aided by the establishment of an official education and training curriculum. In particular, the establishment of a simulator-based educational program and corresponding evaluation methods will spur development of increasingly medical simulators. ExtraCorporeal Circulation SIMulator (ECCSIM-Lite) was used during repeated sessions of undergraduate students (n = 12) using a simple training scenario. Trainees aimed to maintain reservoir volume around a constant mean, and increase or decrease the arterial flow avoiding rapid variations, and their performance was monitored. Ability to prevent backflow was also recorded as a measure of accomplishment. Skills in performances were evaluated by using a scoring system based on task accomplishment. Accomplishment score was improved in all participants after 1 week of training. Accomplishment scores reflecting ability to maintain flow improved to an average of 78%; in the third and final practice session backflow was prevented in 100% of cases. The average reservoir level maintenance score in the flow-up phase was 75%, in the flow-maintenance phase was 92%, and in the flow-down phase was 58%. During skill training, in which trainees learn methods of avoiding adverse events, the use of simulators combined with tractable skills scores can ease the transition from training session to clinical practice. Use of these training scenarios within a perfusion education system also has the advantage of providing an index of trainees' current proficiency and improvement by providing tractable skill scores. In conclusion, the use of ECCSIM-Lite simulations, together with evaluation of task accomplishment over repeated training sessions, is an effective method of basic skill training for perfusionists.

Three-dimensional echo-guided suture of atrial septal defect with Maniceps in an experimental model.

Toward the establishment of suture closure procedures for atrial septal defect or patent foramen ovale under guidance of three-dimensional (3D) echocardiography but without use of cardiopulmonary bypass (off-pump surgery), an experimental study was conducted using a laparoscopic suture instrument, Maniceps. First, the panel setting of the 3D echo system which was optimal for precisely visualizing the surgical instruments on the image display with the least time delay was determined. The optimal setting was: 1) harmonic imaging, 2) no smoothing, 3) low scanning line density, and 4) a scanning range around 55 degrees. Using an ex vivo model of atrial septal defect, 3D echo-guided surgical procedures were attempted in three steps. First, grasping of the edge of the defect with a forceps was attempted. It was feasible in every direction. Reverberation artifact occasionally disturbed imaging of the defect edge. Second, transfixion suture of the facing edges was attempted. Guided by 3D echo, serial sutures were feasible, but interlocking of the thread was a pitfall. Third, continuous suture of the defect was attempted under 3D echo guidance. Following the initial suture bite on one side, continuous suture could be performed under echo guidance. Deformity of the Maniceps needle after repeated sutures was a limitation. In conclusion, suture closure of the defect under 3D echo guidance using the Maniceps system is feasible in an ex vivo ASD model as visualization is optimized by panel setting for guiding surgical procedures.

Association between false lumen segmental arteries and spinal cord ischemia in type A acute aortic dissection.

BACKGROUND: Spinal cord ischemia (SCI) and paraplegia are complications of surgery for type A acute aortic dissection (TAAAD). Since the segmental arteries play a key role in SCI, this study evaluated the association between SCI and false lumen segmental arteries (FLSAs: segmental arteries originating from the false lumen). METHODS: The study included 101 consecutive TAAAD patients (mean age, 66±13; range, 34-89 years) who underwent surgery from January 2011 to April 2017. The diagnosis of TAAAD and the number of FSLAs were determined by preoperative computed tomography (CT). Patients were divided into two groups according to the number of FLSAs at the Th9-L2 level: Group A (N.=13), ≥8 FLSAs; and group B (N.=88), ≤7 FLSAs. Preoperative, perioperative, and postoperative findings were compared between the groups, and risk factors for SCI were evaluated. RESULTS: The frequency of preoperative paralysis was significantly higher in Group A than Group B (P=.0070). The overall incidence of postoperative SCI was 8% (8/101) and significantly higher in Group A than Group B (5/13 [45%] vs. 3/88 (4%), P<0.0001). Hospital mortality was 8% (8/101) and significantly higher in Group A than Group B (3/13 [23%] vs. 5/88 [6%], P=.0302). Multivariate analysis showed that the independent risk factors for SCI were ≥8 FLSAs at Th9-L2 (odds ratio [OR], 20.4; 95% confidence interval [95% CI], 3.34-124.9, P=0.0011) and diabetes mellitus (OR, 22.3; 95% CI, 1.69-294.5; P=0.0184). CONCLUSIONS: In patients who underwent surgery for TAAAD, ≥8 FLSAs at the Th9-L2 levels on preoperative CT was a risk factor for SCI.

Mid-Term Results of Frozen Elephant Trunk Technique for Chronic Aortic Dissection.

Objective: In this study, we report our experience using the frozen elephant trunk (FET) technique for chronic aortic dissection. Methods: Between January 2011 and December 2017, 15 patients underwent total arch replacement (TAR) with the FET technique for chronic aortic dissection (CAD). Results: Hospital mortality was 6.7% (n=1). No patients experienced spinal cord injury. Distal stent-induced new entry (dSINE) occurred in the early postoperative period in one patient. There were four unplanned additional operations to manage dSINE. Five patients suffered from dSINE, and aortoesophageal fistula developed in three of them. Short insertion length of the FET and large angle between the distal edge of the FET and the descending aorta were significantly more common in the dSINE group than in the non-dSINE group. The cumulative survival rates at 1, 3, and 5 years were 93.3%, 93.3%, and 66.4%, respectively. The cumulative aortic event-free rates at 1, 2, and 3 years were 85.7%, 77.1%, and 52.9%, respectively. Conclusion: The FET technique for CAD provided good early results. Short insertion length of the FET, however, can induce dSINE, which requires an additional operation at mid-term. Thus, surgical indication of the FET technique for CAD must be discussed.

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.

Virtual patient simulator for the perfusion resource management drill.

Perfusionists require a detailed understanding of a patient's physiological status while comprehending the mechanics and engineering of the cardiopulmonary bypass system, so it is beneficial for them to obtain relevant practical skills using extracorporeal circulation technology and educational physiological simulators. We designed a perfusion simulator system (ECCSIM: Extracorporeal Circulation SIMulator system) based on a hybrid of a simple hydraulic mock circulation loop linked to a computer simulation model. Patient physiological conditions (height, weight, and cardiac indices) were determined by a parameter estimation procedure and used to accurately reproduce hemodynamic conditions. Extracorporeal circulation trainees in pre-clinical education were able to maintain venous oxygen saturation levels above 50%, except during cardiac standstill and a brief resumption of pulsation. Infant amplitudes of reservoir volume oscillation and flow rate were greatly increased compared with adult cardiovascular parameters, this enabled the instructor to control the difficulty level of the operation using different hemodynamic variations. High-fidelity simulator systems with controllable difficulty levels and high physiological reproducibility are useful in constructing a perfusion resource management environment that enable basic training and periodic crisis management drills to be performed.

Aorto-Esophageal Fistula Caused by Distal Stent Graft-Induced New Entry after Frozen Elephant Trunk Technique for Chronic Aortic Dissection.

We present a case of aorto-esophageal fistula (AEF) caused by distal stent graft-induced new entry (dSINE) after the frozen elephant trunk (FET) technique for chronic aortic dissection. We propose that the combination of the spring-back force and the radial force of the FET may play a role in the occurrence of dSINE, leading to AEF. In this case, we successfully performed a three-stage surgery, including esophagectomy, descending aortic replacement, and esophageal reconstruction. To prevent this critical complication, additional endovascular aortic repair should be performed if the FET is not positioned at the straight portion of the descending aorta.

Development of a new pulsatile ventricular assist device.

We developed a small, lightweight, low-cost implantable ventricular assist device (VAD) for use in smaller Japanese subjects. The major advantage of this pump is the simplicity of its fabrication. Most parts of the pump were shaped from a transparent acrylic block by a turning process, and the diaphragm was made from a silicon sheet. Since this method of construction did not require any complex processes, we could manufacture many pumps of various shapes. We determined the -most efficient shape for the Ebacor VAD using the flow visualization technique. The pump showed an output above 6 liters/min under a driving pressure of 300/-100 mmHg. The pump performance of current VADs is superior to that of the Ebacor VAD, because these pumps are larger. Since the Ebacor VAD is small in size, it can be driven by the driving system of a normal IABP control unit, which many hospitals already have in place. During a 30-day continuous driving performance test of this pump, no problems like performance decrements or water and air leakage were observed.

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.

Long-term results after the box pulmonary vein isolation procedure for chronic atrial fibrillation in mitral valve surgery.

BACKGROUND: We hypothesized that chronic atrial fibrillation (AF) originated from the pulmonary veins, and was maintained by irregular activations of the posterior left atrium. We had performed the box pulmonary vein isolation procedure for the elimination of chronic AF associated with solitary mitral valve disease from 1999 to 2004. This paper evaluated the long-term results of this procedure over more than 6 years, and discussed the role of the pulmonary veins and posterior left atrium in maintaining AF. METHODS: Fifty-three patients were examined after box pulmonary vein isolation procedure concomitant with solitary 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 determined by electrocardiography, and atrial function was evaluated by transthoracic echocardiography. The elimination of chronic AF and the recovery of atrial systolic function after surgery were evaluated over more than 6 years of follow-up. RESULTS: In a total of 462.8 patient years of follow-up (range 6.3 to 11.5 years, mean: 8.9 ± 2.7 years), AF disappeared in 77.3% of the patients (41/53) at 3 months and in 70.6% (36/51) of the patients at 6 years after the box pulmonary vein isolation, respectively. Among the preoperative variables, a long duration of AF and a large diameter of the left atrium were the predictive factors for recurrences of AF (p <0.05). There was no left atrial tachycardia even though we did not perform ablation towards the mitral valve annulus. CONCLUSIONS: The box pulmonary vein isolation procedure can terminate chronic AF associated with solitary mitral valve disease, and maintain a sinus rhythm for more than 6 years in 70% of chronic AF patients. This study implicates the pulmonary veins and posterior left atrium in maintaining chronic AF associated with mitral valve disease.