Publications by authors named "Koichi Sughimoto"

48 Publications

Paracorporeal Support in Pediatric Patients: The Role of the Patient-Device Interaction.

Ann Thorac Surg 2021 Jul 28. Epub 2021 Jul 28.

Department of Pediatric Cardiology University of Alberta, Edmonton AB, Canada; Division of Pediatric Cardiology, Stollery Children's Hospital, Edmonton AB, Canada. Electronic address:

Background: Ventricular assist devices (VADs) are important in the treatment of pediatric heart failure. While paracorporeal pulsatile (PP) devices have historically been used, there has been increased use of paracorporeal continuous (PC) devices. We sought to compare the outcomes of children supported with a PP, PC, or combination of devices.

Methods: Retrospective review (2005-19) of patients <19 years of age from a single center, who received a PC, PP or combination of devices. Patient characteristics were compared between device strategies and Kaplan-Meier survival analysis was performed.

Results: Sixty-six patients were included (62% male, 62% non-congenital heart disease, median age 0.9 years (IQR 0.2, 4.9), median weight 8.5 kg (IQR 4.3, 17.7). PC devices were used in 45% of patients, PP in 35% and a combination in 20%. Patients on PC devices had a lower median weight (p=.02), a higher proportion of CHD (p=.02) and more patients requiring pre-VAD dialysis (p=.01). There was no difference in pre-VAD ECMO (p=.15) use. There was a difference in survival between the three device strategies (p=.02) CONCLUSIONS: Differences in survival was evident, with those on PC support having worse outcomes. Transition from PC to a PP devices was associated with a survival advantage. These findings may be driven by differences in patient characteristics across device strategies. Further studies are required to confirm these findings and to better understand the interaction between patient characteristics and device options.
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http://dx.doi.org/10.1016/j.athoracsur.2021.06.062DOI Listing
July 2021

Coarctation of the aorta with total anomalous pulmonary venous connection: a case report.

AME Case Rep 2021 25;5:11. Epub 2021 Apr 25.

Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.

Total anomalous pulmonary venous connection (TAPVC) and coarctation of the aorta (CoA) rarely occur together. In affected patients, blood is supplied to the lower body by saturated ductal flow. Preoperative echocardiography may not show an acceleration of flow at the isthmus (coarctation), and the oxygen saturation (SpO) at the feet may be satisfactory. Consequently, the severity of CoA is often underestimated before performing surgery. A 6-day-old boy weighing 2.6 kg with a diagnosis of supracardiac TAPVC was referred for surgical correction of his anomaly. The atrial septal defect (ASD) was 6.7 mm in diameter. There was a large patent ductus arteriosus (PDA) without flow acceleration at the preductal entry into the descending aorta. Only the TAPVC repair was planned, but immediately following ligation of the large PDA, the blood pressure in the lower extremity dropped to around 30 mmHg. The ligation was removed. The reason for the blood pressure discrepancy between the upper and the lower body was not clear as there was no arterial line in the upper extremity and a 6.7-mm-diameter ASD can support sufficient blood flow to the lower body without the PDA. A suspected CoA was found and repaired, followed by the TAPVC repair. Caution is necessary when repairing a TAPVC and coexisting large PDA as the severity of the CoA can easily be underestimated due to nonsignificant flow acceleration.
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http://dx.doi.org/10.21037/acr-20-135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060153PMC
April 2021

Markers of peripheral perfusion during high-flow regional cerebral perfusion for aortic arch repair.

J Thorac Cardiovasc Surg 2018 12 28;156(6):2251-2257. Epub 2018 Sep 28.

Department of Cardiovascular Surgery, School of Medicine, Kitasato University, Sagamihara, Japan.

Objectives: High-flow regional cerebral perfusion (HFRCP) provides cerebral and somatic oxygen delivery through collateral vessels during aortic arch repair in small children; however, optimal flow conditions during HFRCP have not been established. We sought to identify markers of peripheral perfusion during HFRCP.

Methods: Between 2009 and 2016, in total 20 consecutive pediatric patients undergoing aortic arch repair with HFRCP were enrolled in this prospective, observational study. Median age was 20 days (range, 6-116 days); median body weight was 2.77 kg (range, 1.8-4.98 kg). Oxygen delivery ratio (DoR) was calculated as the oxygen delivery during HFRCP divided by the oxygen delivery before HFRCP. Regional oxygen saturations on the forehead and on the thigh (rSoT) were monitored during HFRCP, and postoperative creatinine kinase and lactate concentrations were measured as postoperative outcomes. Multivariate analyses were performed to clarify the effectiveness of DoR and rSoT as markers of peripheral perfusion during HFRCP.

Results: No deaths or neurologic impairments occurred. Multivariate analysis showed that the lowest rSoT (P = .005) and cardiopulmonary bypass time (P = .012) predicted postoperative creatinine kinase concentration. DoR was the only factor to predict postoperative lactate concentration (P < .001). Receiver operating characteristic analysis showed that DoR less than 0.66 predicted risk of high postoperative lactate concentration (>5.0 mmol/L), with area under the curve of 0.95.

Conclusions: For aortic arch repair in small children, rSoT and DoR during HFRCP are useful markers for predicting peripheral perfusion. Maintaining higher DoR during HFRCP minimizes postoperative increases in lactate and creatinine kinase concentrations.
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http://dx.doi.org/10.1016/j.jtcvs.2018.08.097DOI Listing
December 2018

Aortic Arch Homograft Reconstruction of Nonconfluent Pulmonary Arteries During Extracardiac Fontan.

World J Pediatr Congenit Heart Surg 2018 09;9(5):582-584

1 Division of Pediatric Cardiothoracic Surgery, British Columbia Children's Hospital, Vancouver, British Columbia, Canada.

Reconstruction of nonconfluent pulmonary arteries during Fontan completion is a challenging technical issue. In this case report, we describe the use of an aortic homograft, including the aortic arch, to complete a Fontan and reconstruct the pulmonary artery confluence in a child with discontinuous pulmonary arteries and bilateral superior caval veins who had undergone bilateral unidirectional Glenn palliation. The configuration of the aortic homograft was ideal to ensure laminar flow from the inferior vena cava to both pulmonary arteries and in maintaining durable elastance posterior to the native aorta.
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http://dx.doi.org/10.1177/2150135118775383DOI Listing
September 2018

Mid-term result of atrioventricular valve replacement in patients with a single ventricle.

Interact Cardiovasc Thorac Surg 2018 12;27(6):895-900

Department of Cardiovascular Surgery, Mitsui Memorial Hospital, Tokyo, Japan.

Objectives: Atrioventricular valve replacement is the last option to treat the atrioventricular valve regurgitation in single ventricle. This study investigates the mid-term outcomes of the atrioventricular valve replacement based on the Japan Cardiovascular Surgery Database registry.

Methods: From 2008 to 2014, 56 patients [34 males (61%) and 22 females (39%)] with a single ventricular circulation, underwent atrioventricular valve replacement. Questionnaires were collected to review operative data, mid-term mortality, morbidity and redo replacement. Risk factor analysis was performed by the Cox regression model for death and redo replacement.

Results: Heterotaxy, a right systemic ventricle and a common atrioventricular valve was present in 46% (26/56), 64% and 57% of patients, respectively. The most common timings for atrioventricular valve replacement were the interstage between the second and third palliations (34%) and after the Fontan operation (34%). Twenty died during the 3.7 ± 2.6-year follow-up. Eleven received redo atrioventricular replacement. The cumulative incidences of redo atrioventricular valve replacement and survival at 3 years were 20% [95% confidence interval (CI) 9-30] and 66% (95% CI 55-80), respectively. Univariable Cox regression analysis revealed that a tricuspid valve was a risk factor for redo valve replacement [hazard ratio (HR) 6.76, 95% CI 1.79-25.6; P = 0.005] and that young age was a risk factor for death (HR 0.77, 95% CI 0.62-0.96; P = 0.019). Fourteen patients required a pacemaker implantation.

Conclusions: Valve replacement for uncontrollable atrioventricular valve regurgitation in single ventricular circulation was associated with a moderately high risk of death, redo replacement and pacemaker implantation, whereas valve replacement at a later period and with a larger prosthetic valve size was associated with low mortality.
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http://dx.doi.org/10.1093/icvts/ivy155DOI Listing
December 2018

Conventional repair of total anomalous venous drainage without primary sutureless technique: surgical tips to prevent pulmonary vein obstruction.

Gen Thorac Cardiovasc Surg 2018 Jul 26;66(7):405-410. Epub 2018 Apr 26.

Department of Cardiovascular Surgery, Kitasato University School of Medicine, 1-15-1, Kitasato, Minami-ward, Sagamihara, Japan.

Objectives: Although primary sutureless technique for total anomalous pulmonary venous drainage has been introduced to reduce postoperative pulmonary vein obstruction (PVO), controversy still exists about superiority of the procedure between the conventional repair and primary sutureless technique at the initial repair. In our unit, the conventional repair has been consistently used based on four important surgical policies: (1) mark incision lines between 2 chambers to gain anatomically natural alignment, (2) place precise stitches by "intima-to-intima" using monofilament suture, (3) adequate orifice size should be guaranteed in greater than expected mitral valve size, (4) do not hesitate to undertake a redo additional anastomosis by a different approach when an echocardiography shows the velocity more than 1.5 m/s. This study aims to evaluate mid-term outcome of the conventional repair for total anomalous pulmonary venous drainage.

Methods: Between 2004 and 2016, consecutive 15 patients who underwent the conventional repair without the primary sutureless technique were included in this study. Survival, Freedom from reoperation, and PVO were retrospectively reviewed.

Results: Mean follow-up period was 4.6 ± 3.7 years. Except for one patient who died of uncontrollable pleural effusion, all other patients survived with 5-year survival rate of 93.3%. For the 14 survivors, there was no PVO, nor reoperation.

Conclusions: Following these policies, the mid-term outcome of the conventional total anomalous pulmonary venous drainage repair was excellent without the primary sutureless technique showing no obstruction. The conventional repair can be safely applied at the initial operation when the morphological condition allows for it.
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http://dx.doi.org/10.1007/s11748-018-0921-2DOI Listing
July 2018

Partial anomalous pulmonary venous drainage repair concomitant with bilateral semilunar valve replacements and pulmonary artery reconstruction for an adult female 20 years after initial truncus arteriosus repair.

Cardiol Young 2018 Mar 8;28(3):514-515. Epub 2018 Jan 8.

Department of Cardiovascular Surgery,Kitasato University School of Medicine,Sagamihara,Japan.

We describe the case of a 21-year-old patient who underwent repairs for multiple lesions including aortic and pulmonary valve replacements, right ventricular outflow tract reconstruction, revision of the right pulmonary artery route, and a repair of partial anomalous pulmonary venous drainage, which was diagnosed during this fourth sternotomy. For these patients with adult CHD, it is most important to address all underlying factors as much as possible at the redo surgery.
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http://dx.doi.org/10.1017/S1047951117002736DOI Listing
March 2018

Surgical strategy for aortic arch reconstruction after the Norwood procedure based on numerical flow analysis.

Interact Cardiovasc Thorac Surg 2018 03;26(3):460-467

Department of Surgery I, Toyama University School of Medicine, Toyama City, Toyama, Japan.

Objectives: Inefficient aortic flow after the Norwood procedure is known to lead to the deterioration of ventricular function due to an increased cardiac workload. To prevent the progression of aortic arch obstruction, arch reconstruction concomitant with second-stage surgery is recommended. The aim of this study was to determine the indications for reconstruction based on numerical simulation and to reveal the morphology that affects the haemodynamic parameters.

Methods: Fifteen patients who underwent the Norwood procedure or arch repair and Damus-Kaye-Stansel anastomosis were enrolled. The pressure gradient in aortic arch was 1.6 ± 3.9 mmHg (ranged from 0 to 12 mmHg) on catheter examination. Six patients who had prominent turbulent flow accompanied with a large flow energy loss index greater than 40 mW/m2 and high wall shear stress greater than 100 Pa underwent arch reconstruction.

Results: After arch reconstruction, the energy loss index significantly decreased from 88.5 ± 50.0 mW/m2 to 23.1 ± 10.4 mW/m2 (P = 0.026) and wall shear stress significantly decreased from 194.5 ± 87.4 Pa to 60.3 ± 40.5 Pa (P = 0.0062). There were 3 late deaths due to heart failure caused by progressive atrioventricular valve regurgitation during the follow-up period (60 months). The systemic ventricular function was preserved in the remaining patients without any pressure gradients in the arch.

Conclusions: Determining the surgical strategy for arch reconstruction based on numerical flow analysis may effectively reduce the ventricular load even if no stenosis or pressure gradients are observed on catheter examination or echocardiography.
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http://dx.doi.org/10.1093/icvts/ivx332DOI Listing
March 2018

Mid-term outcomes of congenital mitral valve surgery: Shone's syndrome is a risk factor for death and reintervention.

Interact Cardiovasc Thorac Surg 2017 11;25(5):734-739

Department of Cardiac Surgery, The Royal Children's Hospital Melbourne, Parkville, VIC, Australia.

Objectives: To study the recent trends and outcomes of congenital mitral valve surgery in children.

Methods: From 2008 to 2014, 84 procedures in 66 consecutive patients (41 procedures in 31 patients with mitral stenosis and 43 procedures in 35 patients with mitral regurgitation) were retrospectively evaluated. The mean age at surgery was 4.3 ± 5.4 years, and 27 patients (41%) were neonates or infants.

Results: Seven (11%) patients died during the follow-up period of 3.2 ± 2.3 years and 5 (71%) were <1 year. Ten mitral valve replacements were performed in 8 patients, including 1 pulmonary valve homograft, 3 Contegra conduits of 12 mm thickness in the intra-annular position and 6 mechanical valves. Shone's syndrome, dysplastic valve, a need for valve replacement and age <1 year were the risk factors for death or reoperation in a univariable analysis, while in a multivariable analysis of all patients, valve replacement and age <1 year remained as risk factors. In a multivariable analysis of 27 patients aged <1 year, mitral valve dysplasia was a significant risk factor for reoperation or death. The 5-year rate of freedom from death or reoperation in neonates or infants was 55% and that in patients aged >1 year was 88% (P = 0.003).

Conclusions: An age of <1 year, mitral valve dysplasia and a need for mitral valve replacement were associated with a higher incidence of death or reoperation. Primary mitral valve replacement or univentricular strategy may have to be considered for symptomatic neonates with Shone's syndrome.
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http://dx.doi.org/10.1093/icvts/ivx211DOI Listing
November 2017

[Perioperative Management of Fontan Operation].

Kyobu Geka 2017 07;70(8):627-633

Department of Cardiovascular Surgery, Kitasato University School of Medicine, Tokyo, Japan.

Surgical results of Fontan operation has been improved over the decades due to the introduction of the staged operations and some modifications of Fontan route from the classical atrio-pulmonary connection to total cavo-pulmonary connection. However, issues remain because of the single ventricular physiology of Fontan circulation. This article explains about the preoperative checklist for Fontan operation and tips on the postoperative management including an early extubation, use of inhaled nitric oxide after extubation, anticoagulation therapy, and efficacy of angiotensin converting enzyme inhibitor, supported by the cutting-edge evidence. Some patients who underwent Fontan operation, however, suffer from protein-losing enteropathy, heart failure, and thus are classified as failing Fontan. Treatment for these patients with failed Fontan is an unsolved problem in the state where heart transplantation is inadequately available in Japan.
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July 2017

Transareolar Video-Assisted Approach to the Atrial Septal Defect and Tricuspid Valve.

Innovations (Phila) 2017 May/Jun;12(3):217-220

From the Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.

Minimally invasive atrial septal defect closure and tricuspid annuloplasty in female patients are normally performed through a right submammary anterior minithoracotomy approach. However, when the aortic root is located higher, the direction of aortic cannulation becomes not ideal through the submammary incision. In such cases, transareolar approach is useful. Through this approach, aortic cannulation and tricuspid operation can be performed with endoscopic assistance, and ASD closure can be performed under direct vision.
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http://dx.doi.org/10.1097/IMI.0000000000000368DOI Listing
March 2018

Daily transient discontinuation of extracorporeal LVAD to prevent thromboembolism of mechanical aortic valve prosthesis.

J Artif Organs 2017 Sep 9;20(3):274-276. Epub 2017 May 9.

Department of Cardiovascular Surgery, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami Ku, Sagamihara, Kanagawa Prefecture, 252-0374, Japan.

Patients with mechanical aortic valves are generally contraindicated for left ventricular assist device (LVAD) insertion because the prosthetic valve often becomes fixed in closed position. A 41-year-old woman with mechanical aortic valve prosthesis experienced sudden chest pain and developed cardiogenic shock. A paracorporeal pulsatile LVAD and a monopivot centrifugal pump as a right VAD (RVAD) were implanted. The mechanical aortic valve was intentionally left in place. Soon after the operation, LVAD support was discontinued daily for few seconds to allow the mechanical aortic valve to open and to avoid thrombus formation. The patient was successfully weaned off RVAD and received anticoagulation therapy with warfarin. On postoperative day 141, she was transferred to a university hospital where a HeartMate II LVAD was implanted, and the aortic valve was successfully replaced with a bioprosthetic valve. The patient is currently awaiting heart transplantation.
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http://dx.doi.org/10.1007/s10047-017-0963-8DOI Listing
September 2017

Outcomes of patients who declined surgery for acute Stanford type A aortic dissection with patent false lumen of the ascending aorta.

Interact Cardiovasc Thorac Surg 2017 07;25(1):47-51

Department of Cardiovascular Surgery, Kitasato University School of Medicine, Kanagawa, Japan.

Objectives: This study aimed to evaluate the outcomes of patients who did not undergo initial aortic surgery for acute Stanford type A aortic dissection with a patent false lumen of the ascending aorta.

Methods: Inpatient and outpatient records were retrospectively reviewed.

Results: We identified 195 patients with acute type A aortic dissection with a patent ascending false lumen between January 1998 and March 2016. Of these, 137 underwent aortic surgery, 16 died before surgery and 42 declined aortic surgery. The ages of the patients who underwent and those who declined aortic surgery were 60.0 ± 10.6 years and 72.3 ± 12.4 years, respectively. The mortality rate of those who underwent and those who declined aortic surgery was 15 and 62% at 30 days and 19% and 67 at 90 days, respectively ( P  < 0.0001). In the 58 patients who did not undergo initial aortic surgery, the maximum aortic diameter was correlated with survival ( P  = 0.0037). At follow-up (3.7 ± 4.5 years; range 0-16.4 years), survival at 1, 5 and 10 years in those who underwent and those who declined initial aortic surgery was 78, 68 and 49%, and 29, 24 and 12%, respectively ( P  < 0.0001).

Conclusions: In this study of patients with acute Stanford type A aortic dissection with a patent false lumen of the ascending aorta, the mortality of those who declined initial aortic surgery was 62% at 30 days and 67% at 90 days, respectively, and a smaller aortic diameter was significantly associated with better survival.
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http://dx.doi.org/10.1093/icvts/ivw451DOI Listing
July 2017

Impact of the location of the fenestration on Fontan circulation haemodynamics: a three-dimensional, computational model study.

Cardiol Young 2017 Sep 5;27(7):1289-1294. Epub 2017 Apr 5.

3Graduate School of Engineering,Chiba University,Chiba,Japan.

Objectives: There is no consensus or theoretical explanation regarding the optimal location for the fenestration during the Fontan operation. We investigated the impact of the location of the fenestration on Fontan haemodynamics using a three-dimensional Fontan model in various physiological conditions.

Methods: A three-dimensional Fontan model was constructed on the basis of CT images, and a 4-mm-diameter fenestration was located between the extracardiac Fontan conduit and the right atrium at three positions: superior, middle, and inferior part of the conduit. Haemodynamics in the Fontan route were analysed using a three-dimensional computational fluid dynamic model in realistic physiological conditions, which were predicted using a lumped parameter model of the cardiovascular system. The respiratory effect of the caval flow was taken into account. The flow rate through the fenestration, the effect of lowering the central venous pressure, and wall shear stress in the Fontan circuit were evaluated under central venous pressures of 10, 15, and 20 mmHg. The pulse power index and pulsatile energy loss index were calculated as energy loss indices.

Results: Under all central venous pressures, the middle-part fenestration demonstrated the most significant effect on enhancing the flow rate through the fenestration while lowering the central venous pressure. The middle-part fenestration produced the highest time-averaged wall shear stress, pressure pulse index, and pulsatile energy loss index.

Conclusions: Despite slightly elevated energy loss, the middle-part fenestration most significantly increased cardiac output and lowered central venous pressure under respiration in the Fontan circulation.
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http://dx.doi.org/10.1017/S1047951117000099DOI Listing
September 2017

Epicardial Implantable Cardioverter-Defibrillator in a 2-Month-Old Infant.

Ann Thorac Surg 2017 Mar;103(3):e263-e265

Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.

We describe the implantation of an implantable cardioverter defibrillator (ICD) in a 2-month-old infant with frequent sustained ventricular tachycardia (VT) refractory to antiarrhythmic agents. An epicardial ICD shock coil lead and pacing leads were placed, as was a cumbersome device console that was stored in a pocket between the left external and internal oblique muscles. These methods were safe and feasible even for such a small infant, and possible adverse events were avoided.
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http://dx.doi.org/10.1016/j.athoracsur.2016.08.040DOI Listing
March 2017

Factors associated with a low initial cerebral oxygen saturation value in patients undergoing cardiac surgery.

J Artif Organs 2017 Jun 4;20(2):110-116. Epub 2017 Jan 4.

Department of Cardiovascular Surgery, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa, 252-0375, Japan.

Regional cerebral oximetry using near-infrared spectroscopy device, an INVOS 5100 C (Medtronic, Minneapolis, MN, USA), during cardiac surgery aims to avoid perioperative neurological impairment, especially during cardiopulmonary bypass. However, it is not uncommon to encounter critically low initial cerebral regional oxygen saturation or a low value unresponsive to intervention. Therefore, it is important to identify factors associated with low saturation value other than true cerebral hypoxia. We investigated the relationship between preoperative regional cerebral oxygen saturation and clinical variables during cardiac surgery. From January 2013 to May 2016, 462 patients underwent elective cardiac surgery. Patient's ≤12 years of age, with acute cerebral infarction, with previous intracranial hemorrhage or neurosurgery, with concomitant aortic surgery, and having off-pump coronary artery bypass surgery were excluded. The remaining 223 patients were monitored by intraoperative regional cerebral oximetry. Univariate analysis found that scalp-cortex distance, cerebrospinal fluid thickness, left ventricular ejection fraction, hemoglobin concentration, estimated glomerular filtration rate, and hemodialysis were significantly correlated with the initial regional oxygen saturation value. Multiple regression analysis revealed that scalp-cortex distance, left ventricular ejection fraction, hemoglobin, and hemodialysis remained as significant variables. A receiver operating characteristic analysis found that for a low initial regional oxygen saturation value of 40%, the thresholds of scalp-cortex distance, left ventricular ejection fraction, and hemoglobin concentration were 17.6 mm, 45.2%, and 7.5 g/dl, respectively. In conclusion, brain atrophy, poor left ventricular function, anemia, and hemodialysis were associated with low initial cerebral regional oxygen saturation values in adult cardiac surgery patients.
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http://dx.doi.org/10.1007/s10047-016-0941-6DOI Listing
June 2017

Influence of Cardiac Function and Loading Conditions on the Myocardial Performance Index - Theoretical Analysis Based on a Mathematical Model.

Circ J 2016 12;80(1):148-56. Epub 2015 Nov 12.

Department of Pediatrics, The University of Tokyo.

Background: The myocardial performance index (MPI) has emerged as a Doppler-derived index for global ventricular function capable of estimating combined systolic and diastolic performance. While several studies have reported its load-dependency, responses of the MPI to various hemodynamic changes have not been fully characterized.

Methods And Results: The response characteristics of the MPI were examined and compared with ejection fractions (EF) by changing hemodynamic parameters within the physiological range in a lumped parameter model of the cardiovascular system. At baseline, the MPI was 0.42 and the EF was 0.68. Heart rate increase resulted in a decrease in EF and an increase in the MPI. Reduction in end-systolic elastance decreased EF and increased the MPI. Volume overload and ventricular stiffening did not affect EF but paradoxically reduced the MPI. Increased afterload due to higher systemic resistance resulted in a decrease in EF and increase in the MPI, but afterload increase caused by reduced arterial compliance led to a decrease in both EF and MPI. These MPI characteristics caused paradoxical improvement of the MPI during disease progression of chronic heart failure in a simulation of mitral regurgitation.

Conclusions: The MPI is affected by a wider variety of hemodynamic parameters than EF. In addition, it is predicted to decrease paradoxically with volume overload, reduction in arterial compliance, or ventricular diastolic stiffening. These MPI characteristics should be considered when assessing cardiovascular dynamics using this index.
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http://dx.doi.org/10.1253/circj.CJ-15-0598DOI Listing
October 2016

Effects of arterial blood flow on walls of the abdominal aorta: distributions of wall shear stress and oscillatory shear index determined by phase-contrast magnetic resonance imaging.

Heart Vessels 2016 Jul 19;31(7):1168-75. Epub 2015 Oct 19.

Center for Frontier Medical Engineering, Chiba University, Chiba, Japan.

Although abdominal aortic aneurysms (AAAs) occur mostly inferior to the renal artery, the mechanism of the development of AAA in relation to its specific location is not yet clearly understood. The objective of this study was to evaluate the hypothesis that even healthy volunteers may manifest specific flow characteristics of blood flow and alter wall shear or oscillatory shear stress in the areas where AAAs commonly develop. Eight healthy male volunteers were enrolled in this prospective study, aged from 24 to 27. Phase-contrast magnetic resonance imaging (MRI) was performed with electrocardiographic triggering. Flow-sensitive four-dimensional MR imaging of the abdominal aorta, with three-directional velocity encoding, including simple morphological image acquisition, was performed. Information on specific locations on the aortic wall was applied to the flow encodes to calculate wall shear stress (WSS) and oscillatory shear index (OSI). While time-framed WSS showed the highest peak of 1.14 ± 0.25 Pa in the juxtaposition of the renal artery, the WSS plateaued to 0.61 Pa at the anterior wall of the abdominal aorta. The OSI peaked distal to the renal arteries at the posterior wall of the abdominal aorta of 0.249 ± 0.148, and was constantly elevated in the whole abdominal aorta at more than 0.14. All subjects were found to have elevated OSI in regions where AAAs commonly occur. These findings indicate that areas of constant peaked oscillatory shear stress in the infra-renal aorta may be one of the factors that lead to morphological changes over time, even in healthy individuals.
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http://dx.doi.org/10.1007/s00380-015-0758-xDOI Listing
July 2016

Skeletonization of the Recurrent Laryngeal Nerve During Norwood Procedure and Aortic Arch Repair.

Ann Thorac Surg 2015 Oct;100(4):1473-5

Department of Cardiac Surgery, The Royal Children's Hospital Melbourne, Australia; Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia; Murdoch Childrens Research Institute, Victoria, Australia. Electronic address:

Recurrent laryngeal nerve injury is a frequent adverse event of aortic arch repair. We hereby present a technique of skeletonization of the recurrent nerve to preserve its function during the Norwood procedure and aortic arch repair.
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http://dx.doi.org/10.1016/j.athoracsur.2015.04.118DOI Listing
October 2015

Single ventricle: repair of atrioventricular valve using the bridging technique.

Multimed Man Cardiothorac Surg 2015 16;2015. Epub 2015 Sep 16.

Department of Cardiac Surgery, Royal Children's Hospital, Melbourne, Australia Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia Murdoch Children's Research Institute, Melbourne, Australia.

Atrioventricular valve regurgitation is one of the predictors of adverse outcomes after the Fontan procedure. We describe our surgical technique of GoreTex (W. L. Gore & Associates, Inc., Flagstaff, AZ, USA) bridge to repair a common atrioventricular valve in single-ventricular circulation. The repair includes a GoreTex strip that is secured to the mid-line of both superior and inferior bridging leaflets and annulus to obtain a better coaptation of the leaflets and prevent further dilatation of the annulus. We have applied this technique for 7 consecutive patients with excellent outcomes.
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http://dx.doi.org/10.1093/mmcts/mmv027DOI Listing
April 2016

Forward Flow Through the Pulmonary Valve After Bidirectional Cavopulmonary Shunt Benefits Patients at Fontan Operation.

Ann Thorac Surg 2015 Oct 28;100(4):1390-6; discussion 1396-7. Epub 2015 Aug 28.

Department of Cardiac Surgery, The Royal Children's Hospital, Melbourne, Australia; Murdoch Childrens Research Institute, Melbourne, Australia; Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia. Electronic address:

Background: The impact of additional pulmonary forward flow (APF) through the pulmonary valve at the time of bidirectional cavopulmonary shunt (BCPS) is unknown.

Methods: Between 2000 and 2010, 276 patients had BCPS and 126 of them were selected, including 60 patients with APF via pulmonary valve and 66 patients, in whom the pulmonary valve was closed. We compared the length of hospital stay and duration of pleural drainage at BCPS and Fontan operations. We also compared the number of surgical interventions before BCPS, the number of operations between BCPS and Fontan operation, Nakata index prior to Fontan operation, grade of atrioventricular valve regurgitation (AVVR), and oxygen saturations prior to Fontan operation.

Results: Prior to BCPS, 20% (12 of 60) of patients with APF and none without APF had pulmonary artery (PA) banding. More patients without APF had systemic-to-PA shunts (p < 0.01). Fontan operation was completed in 58% (35 of 60) of patients with APF and in 68% (45 of 66) of patients without APF (p = 0.34). There was no difference in the length of hospital stay or duration of pleural drainage at BCPS. No significant difference was observed in the number of surgical procedures between BCPS and Fontan operation, grade of AVVR or oxygen saturations before Fontan operation. Children with APF had a higher Nakata index (p = 0.02) prior to Fontan operation, shorter duration of pleural drainage (p = 0.009) and shorter hospital stay (p = 0.009) after Fontan operation.

Conclusions: Children with APF at BCPS had better developed PAs, shorter duration of pleural drainage, and shorter hospital stay after Fontan operation.
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http://dx.doi.org/10.1016/j.athoracsur.2015.05.041DOI Listing
October 2015

Total Cavopulmonary Connection is Superior to Atriopulmonary Connection Fontan in Preventing Thrombus Formation: Computer Simulation of Flow-Related Blood Coagulation.

Pediatr Cardiol 2015 Oct 31;36(7):1436-41. Epub 2015 May 31.

Department of Mechanical Engineering, Graduate School of Engineering, Chiba University, Chiba, Japan.

The classical Fontan route, namely the atriopulmonary connection (APC), continues to be associated with a risk of thrombus formation in the atrium. A conversion to a total cavopulmonary connection (TCPC) from the APC can ameliorate hemodynamics for the failed Fontan; however, the impact of these surgical operations on thrombus formation remains elusive. This study elucidates the underlying mechanism of thrombus formation in the Fontan route by using a two-dimensional computer hemodynamic simulation based on a simple blood coagulation rule. Hemodynamics in the Fontan route was simulated with Navier-Stokes equations. The blood coagulation and the hemodynamics were combined using a particle method. Three models were created: APC with a square atrium, APC with a round atrium, and TCPC. To examine the effects of the venous blood flow velocity, the velocity at rest and during exercise (0.5 and 1.0 W/kg) was measured. The total area of the thrombi increased over time. The APC square model showed the highest incidence for thrombus formation, followed by the APC round, whereas no thrombus was formed in the TCPC model. Slower blood flow at rest was associated with a higher incidence of thrombus formation. The TCPC was superior to the classical APC in terms of preventing thrombus formation, due to significant blood flow stagnation in the atrium of the APC. Thus, local hemodynamic behavior associated with the complex channel geometry plays a major role in thrombus formation in the Fontan route.
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http://dx.doi.org/10.1007/s00246-015-1180-yDOI Listing
October 2015

Mid-term outcome with pericardial patch augmentation for redo left atrioventricular valve repair in atrioventricular septal defect†.

Eur J Cardiothorac Surg 2016 Jan 10;49(1):157-66. Epub 2015 Feb 10.

Department of Cardiac Surgery, The Royal Children's Hospital Melbourne, Melbourne, Australia Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, VIC, Australia Murdoch Childrens Research Institute, Melbourne, Australia.

Objectives: Recurrent left atrioventricular valve (LAVV) regurgitation after atrioventricular septal defect (AVSD) repair is a difficult technical issue. This study exposes the various techniques successively employed to repair the recurrent LAVV regurgitation and their different outcomes. Emphasis however will be put on the new technique used in our unit called cleft patch augmentation, which has been used continuously since 1998 in the anatomical context of normal papillary muscles (NPMs).

Methods: This is a retrospective follow-up study using a Cox regression model for risk analyses from November 1991 to July 2008, including 45 patients who underwent reoperation for LAVV regurgitation after AVSD repair. Of those, 3 patients were lost to follow-up; therefore, 42 patients were included in the study. With regard to the AVSD morphology, there were partial AVSD in 12, complete AVSD in 30.

Results: Age at the primary valve repair was 1.5 ± 2.1 years and the time span to the reoperation was 7.1 years in median (0.41-12.3 years). Age at the first reoperation was 10.1 ± 6.8 years. Median follow-up after the reoperation was 7.4 years. Three patients died in the follow-up period. Freedom from second reoperation at 10 years was 72.8% [59.5-89.0% of 95% confidence interval (CI)]. Of 37 patients with NPMs, freedom from reoperation at 10 years was 59.4% (37.2-94.7% 95% CI) in cleft closure group whereas, in the cleft patch augmentation group, it was 92.3% (78.9-100% 95% CI) (P = 0.04). Five patients required valve replacement.

Conclusions: Surgical result for the redo LAVV repair had good outcomes. In the NPM group, the cleft patch augmentation technique had better results. Various techniques may have to be performed in combination according to the morphological features.
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http://dx.doi.org/10.1093/ejcts/ezv013DOI Listing
January 2016

Hilum-to-hilum Gore-Tex tube replacement of central pulmonary arteries.

Ann Thorac Surg 2015 Jan;99(1):340-2

Department of Cardiac Surgery, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics of the University of Melbourne, and Murdoch Childrens Research Institute, Melbourne, Australia. Electronic address:

Patients born with hypoplastic pulmonary arteries require recurrent procedures of shunting, patch reconstructions, balloon dilatations, and occasionally stenting to achieve adult-size vessels. We have applied a hilum-to-hilum Gore-Tex conduit replacement for the stenosed central pulmonary arteries to 12 consecutive patients with a Gore-Tex tube of 14 mm (9 patients) or 12 mm (3 patients) at a median age of 6.7 years (range, 1.6 to 16.9). There were 8 patients with biventricular repair (2 patients with heart transplantation) and 4 patients with Fontan completions. After a follow-up time of 25 ± 22 months, there was no mortality, reintervention, or restenosis.
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http://dx.doi.org/10.1016/j.athoracsur.2014.06.085DOI Listing
January 2015

Polytetrafluoroethylene bridge for atrioventricular valve repair in single-ventricle palliation.

J Thorac Cardiovasc Surg 2015 Feb 22;149(2):641-3. Epub 2014 Oct 22.

Department of Cardiac Surgery, The Royal Children's Hospital, Melbourne, Australia; Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, Faculty of Medicine, The University of Melbourne, Melbourne, Australia. Electronic address:

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http://dx.doi.org/10.1016/j.jtcvs.2014.10.087DOI Listing
February 2015

Hemodynamic performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study.

Am J Physiol Heart Circ Physiol 2014 Oct 25;307(7):H1056-72. Epub 2014 Jul 25.

Shanghai Jiao Tong University-Chiba University International Cooperative Research Center, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China; Graduate School of Engineering, Chiba University, Inage, Chiba, Japan.

The physiological limitations of the Fontan circulation have been extensively addressed in the literature. Many studies emphasized the importance of pulmonary vascular resistance in determining cardiac output (CO) but gave little attention to other cardiovascular properties that may play considerable roles as well. The present study was aimed to systemically investigate the effects of various cardiovascular properties on clinically relevant hemodynamic variables (e.g., CO and central venous pressure). To this aim, a computational modeling method was employed. The constructed models provided a useful tool for quantifying the hemodynamic effects of any cardiovascular property of interest by varying the corresponding model parameters in model-based simulations. Herein, the Fontan circulation was studied compared with a normal biventricular circulation so as to highlight the unique characteristics of the Fontan circulation. Based on a series of numerical experiments, it was found that 1) pulmonary vascular resistance, ventricular diastolic function, and systemic vascular compliance play a major role, while heart rate, ventricular contractility, and systemic vascular resistance play a secondary role in the regulation of CO in the Fontan circulation; 2) CO is nonlinearly related to any single cardiovascular property, with their relationship being simultaneously influenced by other cardiovascular properties; and 3) the stability of central venous pressure is significantly reduced in the Fontan circulation. The findings suggest that the hemodynamic performance of the Fontan circulation is codetermined by various cardiovascular properties and hence a full understanding of patient-specific cardiovascular conditions is necessary to optimize the treatment of Fontan patients.
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http://dx.doi.org/10.1152/ajpheart.00245.2014DOI Listing
October 2014

Patient-specific assessment of cardiovascular function by combination of clinical data and computational model with applications to patients undergoing Fontan operation.

Int J Numer Method Biomed Eng 2014 Oct 21;30(10):1000-18. Epub 2014 Apr 21.

SJTU-CU International Cooperative Research Center, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.

The assessment of cardiovascular function is becoming increasingly important for the care of patients with single-ventricle defects. However, most measurement methods available in the clinical setting cannot provide a separate measure of cardiac function and loading conditions. In the present study, a numerical method has been proposed to compensate for the limitations of clinical measurements. The main idea was to estimate the parameters of a cardiovascular model by fitting model simulations to patient-specific clinical data via parameter optimization. Several strategies have been taken to establish a well-posed parameter optimization problem, including clinical data-matched model development, parameter selection based on an extensive sensitivity analysis, and proper choice of parameter optimization algorithm. The numerical experiments confirmed the ability of the proposed parameter optimization method to uniquely determine the model parameters given an arbitrary set of clinical data. The method was further tested in four patients undergoing the Fontan operation. Obtained results revealed a prevalence of ventricular abnormalities in the patient cohort and at the same time demonstrated the presence of marked inter-patient differences and preoperative to postoperative changes in cardiovascular function. Because the method allows a quick assessment and makes use of clinical data available in clinical practice, its clinical application is promising.
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http://dx.doi.org/10.1002/cnm.2641DOI Listing
October 2014

Transient hemodynamic changes upon changing a BCPA into a TCPC in staged Fontan operation: a computational model study.

ScientificWorldJournal 2013 10;2013:486815. Epub 2013 Nov 10.

SJTU-CU International Cooperative Research Center, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.

The clinical benefits of the Fontan operation in treating single-ventricle defects have been well documented. However, perioperative mortality or morbidity remains a critical problem. The purpose of the present study was to identify the cardiovascular factors that dominate the transient hemodynamic changes upon the change of a bidirectional cavopulmonary (Glenn) anastomosis (BCPA) into a total cavopulmonary connection (TCPC). For this purpose, two computational models were constructed to represent, respectively, a single-ventricle circulation with a BCPA and that with a TCPC. A series of model-based simulations were carried out to quantify the perioperative hemodynamic changes under various cardiovascular conditions. Obtained results indicated that the presence of a low pulmonary vascular resistance and/or a low lower-body vascular resistance is beneficial to the increase in transpulmonary flow upon the BCPA to TCPC change. Moreover, it was found that ventricular diastolic dysfunction and mitral valve regurgitation, despite being well-known risk factors for poor postoperative outcomes, do not cause a considerable perioperative reduction in transpulmonary flow. The findings may help physicians to assess the perioperative risk of the TCPC surgery based on preoperative measurement of cardiovascular function.
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http://dx.doi.org/10.1155/2013/486815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3844169PMC
July 2014

Blood flow dynamic improvement with aneurysm repair detected by a patient-specific model of multiple aortic aneurysms.

Heart Vessels 2014 May 14;29(3):404-12. Epub 2013 Jul 14.

Department of Cardiac Surgery, The Royal Children's Hospital Melbourne, 50 Flemington Rd, Parkville, VIC, 3052, Australia,

Aortic aneurysms may cause the turbulence of blood flow and result in the energy loss of the blood flow, while grafting of the dilated aorta may ameliorate these hemodynamic disturbances, contributing to the alleviation of the energy efficiency of blood flow delivery. However, evaluating of the energy efficiency of blood flow in an aortic aneurysm has been technically difficult to estimate and not comprehensively understood yet. We devised a multiscale computational biomechanical model, introducing novel flow indices, to investigate a single male patient with multiple aortic aneurysms. Preoperative levels of wall shear stress and oscillatory shear index (OSI) were elevated but declined after staged grafting procedures: OSI decreased from 0.280 to 0.257 (first operation) and 0.221 (second operation). Graftings may strategically counter the loss of efficient blood delivery to improve hemodynamics of the aorta. The energy efficiency of blood flow also improved postoperatively. Novel indices of pulsatile pressure index (PPI) and pulsatile energy loss index (PELI) were evaluated to characterize and quantify energy loss of pulsatile blood flow. Mean PPI decreased from 0.445 to 0.423 (first operation) and 0.359 (second operation), respectively; while the preoperative PELI of 0.986 dropped to 0.820 and 0.831. Graftings contributed not only to ameliorate wall shear stress or oscillatory shear index but also to improve efficient blood flow. This patient-specific modeling will help in analyzing the mechanism of aortic aneurysm formation and may play an important role in quantifying the energy efficiency or loss in blood delivery.
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http://dx.doi.org/10.1007/s00380-013-0381-7DOI Listing
May 2014

Fontan completions over 10 years after Glenn procedures.

Cardiol Young 2014 Apr 27;24(2):290-6. Epub 2013 Mar 27.

2 Department of Cardiac Surgery, Chiba Cardiovascular Center, Ichihara, Japan.

Objective: Despite the broadened indications for Fontan procedure, there are patients who could not proceed to Fontan procedure because of the strict Fontan criteria during the early period. Some patients suffer from post-Glenn complications such as hypoxia, arrhythmia, or fatigue with exertion long after the Glenn procedure. We explored the possibility of Fontan completion for those patients.

Methods: Between 2004 and 2010, five consecutive patients aged between 13 and 31 years (median 21) underwent Fontan completion. These patients had been followed up for more than 10 years (10 to 13, median 11) after Glenn procedure as non-Fontan candidates. We summarise these patients retrospectively in terms of their pre-operative physiological condition, surgical strategy, and problems that these patients hold.

Results: Pre-operative catheterisation showed pulmonary vascular resistance ranging from 0.9 to 3.7 (median 2.2), pulmonary to systemic flow ratio of 0.3 to 1.6 (median 0.9), and two patients had significant aortopulmonary collaterals. Extracardiac total cavopulmonary connections were performed in three patients, lateral tunnel total cavopulmonary connection in one patient, and intracardiac total cavopulmonary connection in one patient, without a surgical fenestration. Concomitant surgeries were required including valve surgeries--atrioventricular valve plasty in three patients and tricuspid valve replacement in one patient; systemic outflow tract obstruction release--Damus-Kaye-Stansel procedure in two patients and subaortic stenosis resection in one patient; and anti-arrhythmic therapies--maze procedure in two patients, cryoablation in two patients, and pacemaker implantation in two patients. All patients are now in New York Heart Association category I.

Conclusion: Patients often suffer from post-Glenn complications. Of those, if they are re-examined carefully, some may have a chance to undergo Fontan completion and benefit from it. Multiple lesions such as atrioventricular valve regurgitation, systemic outflow obstruction, or arrhythmia should be surgically repaired concomitantly.
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http://dx.doi.org/10.1017/S1047951113000280DOI Listing
April 2014
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