Search

OBJECTIVES The actual underlying mechanisms of acute type A aortic dissection (AAAD) are not well understood. The present study aimed to elucidate the mechanism of AAAD using computational fluid dynamics (CFD) analysis. METHODS We performed CFD analysis using patient-specific computed tomography imaging in 3 healthy control cases and 3 patients with AAAD. From computed tomography images, we made a healthy control model or pre-dissection model for CFD analysis. Pulsatile cardiac flow during one cardiac cycle was simulated, and a three-dimensional flow streamline was visualized to evaluate flow velocity, wall shear stress and oscillatory shear index (OSI). RESULTS In healthy controls, the transvalvular aortic flow was parallel to the ascending aorta. There was no spotty high OSI area at the ascending aorta. In pre-dissection patients, accelerated transvalvular aortic flow was towards the posterolateral ascending aorta. The vortex flow was observed on the side of the lesser curvature in mid-systole and expanded throughout the entire ascending aorta during diastole. Systolic wall shear stress was high due to the accelerated aortic blood flow on the side of the greater curvature of the ascending aorta. On the side of the lesser curvature, high OSI areas were observed around the vortex flow. In all pre-dissection cases, a spotty high OSI area was in close proximity to the actual primary entry site of the future AAAD. CONCLUSIONS The pre-onset high OSI area with vortex flow is closely associated with the future primary entry site. Therefore, we can elucidate the mechanism of AAAD with CFD analysis.

Objectives This study aimed to evaluate whether cardiac magnetic resonance imaging (MRI)-derived right ventricular (RV) assessment can facilitate risk stratification among patients with ischaemic cardiomyopathy who underwent surgical ventricular reconstruction (SVR). Methods We retrospectively analysed 53 patients who underwent SVR. The patients were preoperatively evaluated using cardiac MRI. Cine-MRI was acquired for left ventricular (LV) and RV volume. Gadolinium-enhanced MRI was performed to evaluate LV scarring. The mid-term (median, 58 months) risk factors of all-cause mortality and major adverse cardiac events were analysed. Results A significant reduction in LV end-diastolic and end-systolic volume index and an increase in LV ejection fraction were observed early after SVR. RV end-diastolic volume index (RVEDVI) and RV end-systolic volume index (RVESVI) decreased after SVR (preoperative versus postoperative: RVEDVI, 71 ± 24 vs 62 ± 17 ml/m2, P = 0.006; RVESVI, 44 ± 26 vs 37 ± 16 ml/m2, P = 0.033), but RV ejection fraction did not change (preoperative versus postoperative: RV ejection fraction 40.8±14.6 vs 42.0±11.0%, P = 0.067). At follow-up, 25 deaths and 31 major adverse cardiac events occurred. After adjustment for age, creatinine level and preoperative mitral regurgitation grade, the Cox-hazard model indicated that RVEDVI [P = 0.006, hazard ratio (HR) 1.03, 95% confidence interval (CI) 1.01-1.05] and RVESVI [P = 0.007, HR 1.02, 95% CI 1.01-1.04] were significant predictors for all-cause mortality. As for major adverse cardiac events, RVEDVI (P = 0.007, HR 1.03, 95% CI 1.01-1.05), RVESVI (P = 0.002, HR 1.03, 95% CI 1.01-1.04) and RV ejection fraction (P = 0.018, HR 0.97, 95% CI 0.94-0.99) were significant. Conclusions RV parameters were more sensitive than LV parameters for predicting worse outcomes following SVR. Preoperative assessment of RV volume and function using cardiac MRI may improve the risk stratification of SVR.

Objectives We aimed to investigate the outcomes of surgical ventricular reconstruction (SVR) for ischaemic cardiomyopathy and to identify ideal candidates for this procedure using cardiac magnetic resonance imaging (MRI) studies. Methods We retrospectively examined 50 patients who underwent SVR and were preoperatively evaluated using cardiac MRI from 2004 to 2014. Cine MRI and gadolinium-enhanced MRI were performed to evaluate left ventricular (LV) volume and scarring. The midterm (median, 2.5 years) risk factors of cardiac death or major adverse cardiac events (MACEs) were analysed. Patients were divided into three groups-those with preoperative indexed LV end-systolic volume (LVESVI) of ≤100 ml/m2 (Group 1), those with LVESVI of >100 and ≤130 ml/m2 (Group 2) and those with LVESVI of >130 ml/m2 (Group 3)-and examined. Results In total, 17 patients exhibited MACEs at follow-up. Kaplan-Meier analysis showed that the 5-year rate of freedom from MACEs was 66%. The Cox hazard model indicated that preoperative LVESVI was the only significant predictor for MACEs (P = 0.006; hazard ratio, 1.02; 95% confidence interval, 1.01-1.04). Moreover, a significant reduction in LVESVI and an increase in LV ejection fraction (LVEF) were observed early after SVR (preoperative versus postoperative: LVESVI, 110 ± 44 vs 68 ± 28 ml/m2, P 130 ml/m2, the number of non-viable segments was a significant risk factor for MACEs. Conclusions Patients with preoperative LVESVI ranging from 100 to 130 ml/m2 had fairly better outcomes, and the percentage improvement in LVEF and the percentage reduction in LVESVI were more pronounced in these patients. Hence, accurate preoperative assessments of LV volume and viability testing using cardiac MRI studies are essential for better stratification of the SVR procedure.

OBJECTIVE: A number of factors limit the effectiveness of current aortic arch studies in assessing optimal neuroprotection strategies, including insufficient patient numbers, heterogenous definitions of clinical variables, multiple technical strategies, inadequate reporting of surgical outcomes and a lack of collaborative effort. We have formed an international coalition of centres to provide more robust investigations into this topic. METHODS: High-volume aortic arch centres were identified from the literature and contacted for recruitment. A Research Steering Committee of expert arch surgeons was convened to oversee the direction of the research. RESULTS: The International Aortic Arch Surgery Study Group has been formed by 41 arch surgeons from 10 countries to better evaluate patient outcomes after aortic arch surgery. Several projects, including the establishment of a multi-institutional retrospective database, randomized controlled trials and a prospectively collected database, are currently underway. CONCLUSIONS: Such a collaborative effort will herald a turning point in the surgical management of aortic arch pathologies and will provide better powered analyses to assess the impact of varying surgical techniques on mortality and morbidity, identify predictors for neurological and operative risk, formulate and validate risk predictor models and review long-term survival outcomes and quality-of-life after arch surgery.

We report a case of a Marfan syndrome patient who developed a complicated clinical course after total aortic repair using a hybrid technique. After hybrid total aortic repair, this patient was required to undergo open thoracic and thoracoabdominal aortic repair due to impending rupture of the aorta. Moreover, the abdominal aortic graft was rereplaced due to debranching graft occlusion of the coeliac artery and the left renal artery.

Objective: To determine whether one and one half ventricular repair (1.5VR) is definitely superior to the Fontan procedure in patients having hypoplastic right ventricle (RV) in the setting of pulmonary atresia with intact ventricular septum (PA/IVS) or its relatives, in terms of results in the longer term. Method: Since1987, 1.5VR has been chosen in seven patients with PA/IVS and in six having PS with hypoplastic RV. On preoperative catheterization, right ventricular end-diastolic volume (RVEDV) was 47 ^ 23% of the anticipated normal value, and annular diameter of the tricuspid valve (TVD) 72 ^ 22% of normal (Z value being 22.4 ^ 2.1). Follow-up term was 3 ‐ 15 (10 ^ 4) years. Results: All patients survived 1.5VR, but one patient died of arrhythmia 9 years later. Freedom from arrhythmia was 80 and 20% at 10 and 12 years, respectively. Two patients have undergone conversion to the Fontan circulation, but none to true biventricular physiology. Consecutive catheterization (1, 5, and 10 years after 1.5VR) demonstrated no changes in %RVEDV or %TVD. Cardiac index was 2.4 ^ 0.6 l/min per m 2 at either 5 or 10 years. RA pressure was 9 ^ 3 and 12 ^ 2 mmHg at 5 and 10 years, respectively. Smaller %RVEDV and %TVD were associated with episodes of atrial arrhythmia and higher RA pressure. Exercise testing showed anaerobic threshold of 16.6 ^ 3.4 ml/kg per min and 13.1 ^ 2.7 ml/kg per min at 5 and 10 years, respectively. These values were equivalent to those in patients with classical tricuspid atresia or PA/IVS undergoing the Fontan procedure, and unequivocally inferior to those in patients having PA/IVS. who could have undergone biventricular repair. Conclusion: Although we previously expected reasonable functional results after 1.5VR between the Fontan circulation and biventricular physiology, this was not always the case in patients having pulmonary atresia or stenosis with intact ventricular septum. q 2003 Elsevier B.V. All rights reserved.

Objectives To obtain predictive information regarding aortic disease, we evaluated how blood flow inside the aortic arch was influenced by thoracic aortic aneurysms. In addition, to reveal the optimal intraoperative management in these cases, we examined blood flow during right subclavian arterial (rSCA) perfusion using computational fluid dynamics (CFD). Methods Patient-specific models of the aortic arch were made with six different patterns based on the computed tomographic images. CFD models with finite volume methods were created to simulate the physiological pulsatile flow including the peripheral reflection wave, characteristic impedance and autonomous regulation system. Flow stream patterns, wall shear stress (WSS) and the oscillatory shear index (OSI) were calculated during one cardiac cycle. Furthermore, flow streamlines during rSCA perfusion were simulated under different perfusion flows. Results Aortic dilatation caused vortical disturbed flow in a dilated space, resulting in turbulent flow not only inside the aneurysm but also in the proximal and/or distal normal aortic portion. In patients with a dilated thoracic aorta, there was a helical spiral flow with a circumferential vortex in systole. In patients with an arch aneurysm, turbulent flow inside the aneurysm caused a high OSI at the tip of the aneurysm. A high OSI was detected at the orifice of the supra-aortic branches, sinotubular junction, posterior lateral side of the ascending aorta and lesser curvature of the proximal descending aorta. rSCA perfusion revealed that the right common carotid artery was perfused by blood flow from rSCA throughout the cardiac cycle. With 75% of the flow from the rSCA, blood flow from the heart reached the left common carotid and subclavian artery only during a short period during the peak of systole. Conclusions A dilated aorta causes a turbulent flow pattern in the aortic arch. The high OSI site was similar to the favourite entry site for acute aortic dissection, indicating the causal relationship between mechanical stress and acute aortic dissection. rSCA cannulation might be cerebroprotective from ascending aortic plaque.

Figure 1: Preoperative computed tomography showed hourglass type of supravalvular aortic stenosis and aneurysmal changes of the innominate and the left subclavian artery. When she underwent ventricular septal defect repair at the age of 4 months, transverse aortotomy was made for evaluating a bicuspid aortic valve. Probably the transverse aortotomy was closed by a continuous suture, which, by definition, could not develop and grow with time, resulting in a tight aortic stenosis. Figure 2: Postoperative computed tomography after aortic root replacement with mechanical-valved conduit and total arch replacement with a fourbranched graft. The patient tolerated the procedure well and was discharged 2 weeks after surgery.

We read with great interest the article by Urbanski et al. [1] about aortic arch surgery using a mild-to-moderate hypothermic circulatory arrest. They evaluated a large series of patients who underwent aortic arch surgery in an elective setting. The mean temperature at circulatory arrest was 29.9°C and the mean duration of circulatory arrest was only 18 min. Surgical results were remarkable. Thirty-day mortality was only 0.9%, permanent neurological deficits and temporary neurological deficits were both also 0.9%, respectively, and there was no paraplegia. They showed quite a low incidence of postoperative acute renal failure and respiratory failure. In this series, an acute aortic dissection was excluded and most of the patients’ indication for surgery was degenerative or atherosclerotic disease. Interestingly, 299 (86%) patients had aortic valve disease and 312 (90%) patients underwent concomitant aortic valve surgery, although the reports of other large series showed that only 8% of patients had an aortic root replacement and 3.8% of patients had an aortic valve replacement [2]. Probably, in these authors’ report, many patients had aortic valve stenosis and/or regurgitation with an ascending aortic aneurysm. For this pathology, it is often an aneurysm which extends to the proximal aortic arch; therefore, sometimes a proximal arch replacement is required in addition to aortic valve or root surgery. In this setting, open distal anastomosis is an appropriate procedure to repair the proximal aortic arch. However, compared to a distal aortic arch aneurysm, the atherosclerotic change in the anastomosis site would be mild and the anastomsis technique would not be as complex and time-consuming. For repairing the distal aortic arch aneurysm, the distal anastomosis site could be deep inside the chest cavity and the aortic arch usually has significant atherosclerotic changes. Therefore, selective cerebral perfusion time and circulatory arrest time could be longer than the proximal arch repair and the risk of permanent neurological deficit could be higher. We believe that it is difficult to generalize the authors’ technique and strategy to all kinds of patient pathologies, because patient characteristics are extraordinary in this report.