Miyuki Shibata

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.

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.

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

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.

Norwood Procedure Performed on a Patient With Trisomy 13

Trisomy 13 is associated with a variety of congenital anomalies, some of which are life-threatening and related to poor prognosis. Therefore, cardiac surgery is rarely offered to these patients, especially to those with complex cardiac anomalies. We report the case of a neonate weighing 2324 g who was born with severe congenital heart defects. Transthoracic echocardiography revealed the diagnoses of asplenia, single ventricle, aortic stenosis, coarctation of the aorta, hypoplastic aortic arch, and total anomalous pulmonary venous return. She was hemodynamically unstable. Palliative Norwood procedure with right ventricle-pulmonary artery conduit (RV-PA conduit) was performed at the age of 1 day to save her life. On postoperative day 7, chromosome analysis revealed trisomy 13. Echocardiography revealed good heart function; stable hemodynamic status was achieved with minimal amounts of inotropic agents. However, she developed anuria, which did not improve despite situational possible interventions, including peritoneal dialysis and continuous hemodiafiltration. On postoperative day 37, she succumbed to sudden cardiorespiratory failure. Nevertheless, this case indicates that a neonate with trisomy 13 can have a better chance at survival with cardiac surgery such as the Norwood procedure with an RV-PA conduit.