Tetsuya Horai

Key success factors for thoracic endovascular aortic repair for non-acute Stanford type B aortic dissection †

OBJECTIVES We aimed to determine the key factors associated with successful early and late outcomes after thoracic endovascular aortic repair (TEVAR) for non-acute Stanford type B aortic dissection at our institution. METHODS Inpatient and outpatient records were retrospectively reviewed. Patients operated on within 14 days after the onset of acute aortic dissection and those with rupture or malperfusion were excluded. RESULTS Forty-five patients (mean age, 55.5 ± 13.1 years; 23-79 years) underwent 53 TEVAR operations for non-acute Stanford type B aortic dissection between 1998 and 2012. Thirty-four patients had a patent false lumen and 19 had an ulcer-like projection (ULP). No early mortality was observed. At late follow-up (7.5 ± 3.9 years) of the 45 patients, survival after the initial TEVAR was 100, 86 and 63%; freedom from aortic reintervention was 87, 73 and 59%; and freedom from open aortic surgery was 89, 84 and 73%, at 1, 5 and 10 years, respectively. Of 15 late deaths, 2 were due to aortic rupture and 2 were operative deaths associated with aortic surgery. Of the 34 patients with patent false lumens before TEVAR, 25 had their descending false lumens thrombosed; of these 25, 16 had remodelling of the descending aorta; and of these 16, 4 had complete obliteration of the false lumen of the entire aorta. By bivariate analysis, the site of the primary entry and age were significantly associated with thrombosis of the descending false lumen, maximum aortic diameter was associated with remodelling of the descending aorta, and absence of abdominal branches arising from the false lumen was associated with complete obliteration of the false lumen of the entire aorta. CONCLUSIONS The early results of TEVAR for non-acute Stanford type B aortic dissection were favourable. However, for cases with patent false lumens, complete obliteration of the false lumen of the entire aorta was difficult to achieve. Absence of the primary entry at the outer curvature of the distal aortic arch, younger age, small aortic diameter and absence of the abdominal aortic branches arising from the false lumen were the key success factors.

Impact of the entry site on late outcome in acute Stanford type B aortic dissection

OBJECTIVES This study aimed to investigate whether the entry site of acute type B aortic dissection affects late outcomes. METHODS Inpatient and outpatient records were retrospectively reviewed. RESULTS We identified 224 cases of acute type B aortic dissection between 1998 and 2013. Of these 224 patients, 168 were men and the age was 64.2 ± 12.6 (range 23-94) years, from which 130 presented with the entry at a location downstream of the distal aortic arch, 67 with the entry at the outer curvature of the distal aortic arch and 27 with the entry at the inner curvature. At the initial presentation, 127 patients had descending false lumen thrombosis. The 30-day mortality rate was 2%, and 8% of patients had malperfusion. The entry at the outer curvature was associated with a higher risk of 30-day mortality. Patients with the entry at a location downstream were significantly older, and had a higher chance for primarily thrombosed descending false lumen and a lower risk of malperfusion. At follow-up (6.0 ± 4.1 years), the actuarial survival rates were 97, 83 and 60%, freedoms from open aortic surgery were 96, 91 and 86%, aortic intervention were 73, 66 and 63% and aortic events were 71, 60 and 52% at 1, 5 and 10 years, respectively. Multivariate logistic regression analysis revealed that the outer curvature entry and maximum aortic diameter were correlated with open aortic surgery, aortic intervention and aortic events. Of the 127 patients with primarily thrombosed false lumen, the outer curvature entry was significantly correlated with aortic events. CONCLUSIONS The primary entry at the outer curvature of the distal aortic arch, as well as the large aortic diameter, is associated with a higher risk of late open aortic surgery, aortic intervention and aortic events in acute type B aortic dissection. Thus, the entry site should be taken into consideration in the establishment of an appropriate treatment indication of type B aortic dissection.

Pulmonary Annulus Growth After the Modified Blalock-Taussig Shunt in Tetralogy of Fallot

BACKGROUND In tetralogy of Fallot (TOF), it is well known that postoperative pulmonary regurgitation reduces right ventricular function during long-term follow-up. Complete repair without a transannular patch should help avoid pulmonary regurgitation. Recently, primary complete repair has been preferred to the staged repair with use of a Blalock-Taussig shunt (BTS) even in neonates or small infants; however, little has been reported about the influence of a BTS on pulmonary annular growth. METHODS We examined 40 patients with TOF or double-outlet right ventricle with pulmonary stenosis. Twenty-one patients received a BTS before complete repair, whereas 19 patients underwent primary complete repair. Pulmonary annular size was measured by echocardiography before BTS, complete repair, or both, and ventricular volume was measured by cardiac catheterization. RESULTS There were no significant differences in complete repair age or body size between the groups. Pulmonary annulus sizes in the BTS group were smaller than those in the primary repair group (Z score, -5.1 ± 2.5 vs -3.7 ± 1.8). After the BTS, significant annular growth (Z score, -2.8 ± 2.1) was observed (p = 0.0028), with a significant increase in left ventricular end-diastolic volume (p = 0.015). When patients with severe pulmonary stenosis (Z score > -7.0) were excluded, pulmonary annular preservation at complete repair was achieved in 64.7% (11/17) of the BTS group and 36.8% (7/19) of the primary repair group (p = 0.088). CONCLUSIONS The BTS increased the pulmonary annular size and the left ventricular volume during the 6 months before complete repair, resulting in preservation of the pulmonary valve function.

Two-stage operation for Stanford type A acute aortic dissection originating from Kommerell's diverticulum

We report a rare case of Stanford type A acute aortic dissection involving an aberrant right subclavian artery and originating from Kommerells diverticulum in a 52-year old man. Initially, as an emergency measure, total arch replacement and right axillary artery reconstruction were performed. However, due to the subsequent enlargement of the false lumen, thoracic endovascular aortic repair and right subclavian artery coiling were performed successfully 5 months after the first operation. Herein, we describe surgical management approaches for the treatment of a Stanford type A acute aortic dissection with aberrant right subclavian artery.

Effect of Additional Preoperative Administration of the Neutrophil Elastase Inhibitor Sivelestat on Perioperative Inflammatory Response After Pediatric Heart Surgery With Cardiopulmonary Bypass

Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response. Our previous reports revealed that prophylactic sivelestat administration at CPB initiation suppresses the postoperative acute inflammatory response due to CPB in pediatric cardiac surgery. The purpose of this study was to compare the effects of sivelestat administration before CPB and at CPB initiation in patients undergoing pediatric open-heart surgery. Twenty consecutive patients weighing 5-10 kg and undergoing ventricular septal defect closure with CPB were divided into pre-CPB (n = 10) and control (n = 10) groups. Patients in the pre-CPB group received a 24 h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the induction of anesthesia and an additional 0.1 mg/100 mL during CPB priming. Patients in the control group received a 24-h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the commencement of CPB. Blood samples were tested. Clinical variables including blood loss, water balance, systemic vascular resistance index, and the ratio between partial pressure of oxygen and fraction of inspired oxygen (P/F ratio) were assessed. White blood cell count and neutrophil count as well as C-reactive protein levels were significantly lower in the pre-CPB group according to repeated two-way analysis of variance, whereas platelet count was significantly higher. During CPB, mixed venous oxygen saturation remained significantly higher and lactate levels lower in the pre-CPB group. Postoperative alanine aminotransferase and blood urea nitrogen levels were significantly lower in the pre-CPB group than in the control group. The P/F ratio was significantly higher in the pre-CPB group than in the control group. Fluid load requirement was significantly lower in the pre-CPB group.Administration of sivelestat before CPB initiation is more effective than administration at initiation for the suppression of inflammatory responses due to CPB in pediatric open-heart surgery, with this effect being confirmed by clinical evidence.

Synchronization of the Flow and Pressure Waves Obtained With Non-Simultaneous Multipoint Measurements

The use of measured data as boundary conditions renders hemodynamic simulations more patient-specific. However, synchronized acquisition of data at multiple locations is often difficult in clinical practice. This study proposes a method for resynchronizing measured data for use as boundary conditions for flow simulations using frequency analyses, and discusses the optimal cut-off frequency for differentiating cardiac and respiratory variation in hemodynamic data during resynchronization. To demonstrate the utility of the method, a Fontan circulation, which is the final palliative result with single-ventricle physiology, was used. The results suggest that it is optimal to set a cut-off frequency that gives a local minimum in the power spectrum that is slightly lower than the peak frequency of the heartbeat. Additionally, the total energy loss depended on the cut-off frequency, although the overall flow patterns appeared to be similar. The method is applicable to cardiovascular systems other than the Fontan circulation, where hemodynamic data with multifactorial fluctuations are required at various locations but simultaneous measurements are not possible.

Optimal Graft Size of Modified Blalock-Taussig Shunt for Biventricular Circulation in Neonates and Small Infants

The modified Blalock-Taussig shunt (mBTS) is one of the most important palliative procedures in congenital heart surgery. However, in neonates and small infants, operative mortality and morbidity due to excessive pulmonary blood flow or shunt failure remains high. In this study, a small shunt graft (3.0-mm diameter) was estimated to determine the optimal shunt graft size of BTS as an initial palliation for ultimate biventricular circulation. Eighteen patients weighing an average 3.5 kg who underwent mBTS from July 2004 to January 2013 at our institute were reviewed. We divided the study cohort into two groups: group S (n = 10) included patients with 3.0-mm diameter shunt grafts, and group L (n = 8) included patients with 3.5-mm diameter shunt grafts. There were no hospital deaths or shunt occlusion in either group. One group L patient (12.5%) had cardiogenic shock due to excessive pulmonary blood flow. There were no differences in postoperative arterial oxygen saturation (SaO2) between the groups. There were no differences in body weight at intracardiac repair (ICR) between the groups. During the interstage to ICR, body weight gain was significantly greater in group S than in group L (P = 0.008). The small shunt graft (3.0-mm diameter) in BTS was safe, provided adequate pulmonary blood flow, and led to significant weight gain between mBTS and ICR for ultimate biventricular circulation in neonates and small infants with low body weight.

Elephant trunk in a small-calibre true lumen for chronic aortic dissection: cause of haemolytic anaemia?

OBJECTIVES The elephant trunk technique for aortic dissection is useful for reducing false lumen pressure; however, a folded vascular prosthesis inside the aorta can cause haemolysis. The purpose of this study was to investigate whether an elephant trunk in a small-calibre lumen can cause haemolysis. METHODS Inpatient and outpatient records were retrospectively reviewed. RESULTS Two cases of haemolytic anaemia after aortic surgery using the elephant trunk technique were identified from 2011 to 2013. A 64-year-old man, who underwent graft replacement of the ascending aorta for acute Stanford type A aortic dissection, presented with enlargement of the chronic dissection of the descending aorta and moderate aortic regurgitation. A two-stage surgery was scheduled. Total arch replacement with an elephant trunk in the true lumen and concomitant aortic valve replacement were performed. Postoperatively, he developed severe haemolytic anaemia because of the folded elephant trunk. The anaemia improved after the second surgery, including graft replacement of the descending aorta. Similarly, a 61-year-old man, who underwent total arch replacement for acute Stanford type A aortic dissection, presented with enlargement of the chronic dissection of the descending aorta. Graft replacement of the descending aorta with an elephant trunk inserted into the true lumen was performed. The patient postoperatively developed haemolytic anaemia because of the folded elephant trunk, which improved after additional stent grafting into the elephant trunk. CONCLUSIONS A folded elephant trunk in a small-calibre lumen can cause haemolysis. Therefore, inserting an elephant trunk in a small-calibre true lumen during surgery for chronic aortic dissection should be avoided.

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

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.

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

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.