A Fibrin-Thrombin Based In Vitro Perfusion System to Study Flow-Related Prosthetic Heart Valves Thrombosis.

Prosthetic heart valve (PHV) replacement has increased the survival rate and quality of life for heart valve-diseased patients. However, PHV thrombosis remains a critical problem associated with these procedures. To better understand the PHV flow-related thrombosis problem, appropriate experimental models need to be developed. In this study, we present an in vitro fibrin clot model that mimics clot accumulation in PHVs under relevant hydrodynamic conditions while allowing real-time imaging. We created 3D-printed mechanical aortic valve models that were inserted into a transparent glass aorta model and connected to a system that simulates human aortic flow pulse and pressures. Thrombin was gradually injected into a circulating fibrinogen solution to induce fibrin clot formation, and clot accumulation was quantified via image analysis. The results of valves positioned in a normal versus a tilted configuration showed that clot accumulation correlated with the local flow features and was mainly present in areas of low shear and high residence time, where recirculating flows are dominant, as supported by computational fluid dynamic simulations. Overall, our work suggests that the developed method may provide data on flow-related clot accumulation in PHVs and may contribute to exploring new approaches and valve designs to reduce valve thrombosis.

Animal Study of a Novel Device for Clampless Proximal Anastomosis in Coronary Bypass Surgery.

PURPOSE: Limitations of existing techniques for clampless proximal anastomosis (CPA) in coronary artery bypass grafting include air emboli and excessive bleeding. This study evaluated the safety and performance of a new device for performing CPA. DESCRIPTION: The device includes a temporary adjustable sealing element that is connected by a catheter to a handle that controls its opening and closure. An aortic punch is mounted on the catheter and activated by a detachable handle. EVALUATION: Six adult female swine underwent partial coronary artery bypass grafting that included construction of a CPA using autologous arterial or venous conduits. During anastomosis construction, good sealing was achieved in all cases, and a blower was not needed in 4 of 6 animals. In the first 2 cases, the blower was intermittently used in 14 % of the entire anastomosis construction time. A mean flow rate of 140.0 ± 52.9 mL/min was measured for the arterial grafts and 666.7 ± 230.9 mL/min for the venous grafts. CONCLUSIONS: The VIOLA device (Vascular Graft Solutions, Tel Aviv, Israel) is safe and associated with good hemostasis and minimal use of a blower during CPA construction in a swine model.

Cardiac surgery in patients with a porcelain aorta in the era of transcatheter valve implantation.

OBJECTIVES: New surgical and perfusion techniques allow the avoidance of deep hypothermia during open aortic arch surgery, which is generally necessary in patients with an unclampable porcelain aorta. The aim of the study was to evaluate operative and long-term results in patients with a porcelain aorta who underwent conventional cardiac surgery using current surgical and perfusion techniques. METHODS: Between November 2003 and February 2012, 30 consecutive patients (mean age 68 ± 11 years, 10 patients had previous cardiac surgery with use of glue in 5 of them) with porcelain aorta diagnosed by computed tomography and defined as a severe circular calcification of the proximal thoracic aorta were referred for cardiac surgery. All patients underwent conventional surgery with arterial cannulation of the innominate (8) or a carotid artery (22) for arterial return. During mild hypothermic circulatory arrest, unilateral cerebral perfusion through the arterial line was performed for cerebral protection. The valve surgery consisted of aortic, mitral or double valve repair in 23, 3 and 4 cases, respectively. Aortic surgery (17 complete root replacements with valve composite grafts and 22 arch replacements) and coronary revascularization due to coronary heart disease (15) were the most frequent concomitant procedures. RESULTS: Thirty-day mortality was 3.3% (1 patient died of bowel ischaemia caused by severe stenosis of the celiac and upper mesenteric arteries) and the rate of permanent neurological deficit was 3.3% as well. Two further patients died during the follow-up at age 91 and 82 years, respectively; however, no death was cardiac or valve related. The actuarial survival at 5 years was 87.3 ± 7.2%. There were no cardiac reoperations, new interventions or aortic- or valve-related events noted during the median follow-up of 45 months (range 0.1-106.0). CONCLUSIONS: Conventional cardiac and aortic surgery offers definitive repair and can be performed safely using current perfusion and operative techniques. Although more invasive, this surgical technique provides mortality and morbidity rates that do not exceed those reported for transcatheter valve implantation. The curative replacement of the pathological proximal aorta, which is one of the most main sources of cerebral embolism, leads to excellent neurological outcome during mid- to long-term follow-up.

Open aortic arch replacement in the era of endovascular techniques.

OBJECTIVES: Despite the progress in protection and surgical techniques, the proponents of endovascular techniques for aortic arch repair still consider conventional arch replacement to be high risk, mostly due to deep hypothermia, which in the past was generally used for cerebral and organ protection. The aim of the study was to evaluate the operative results of open aortic arch replacement using current perfusion and surgical techniques in which deep hypothermia is avoided. METHODS: Between October 2004 and February 2012, 131 consecutive patients with non-acute-dissected aortic arch pathology (mean age: 66 ± 11 years) were referred for surgery. All patients were operated on conventionally using circular aortic arch replacement with repair of one (10), two (58) or all arch branches (63). The adjacent aorta was replaced in all cases (ascending--115, descending--2 and both--14). Nine (6.9%) patients had previous neurological defects with residual symptoms and 17 (13.0%) had previous cardiac surgery. RESULTS: Either unilateral (130) or bilateral (1) cerebral perfusion at a blood temperature of 28°C (mean duration 36 ± 14, range: 16-80 min) was performed for brain protection during circulatory arrest under mild-to-moderate hypothermia (mean rectal temperature 30.0 ± 1.6°C). Concomitant cardiac procedures, mostly on the aortic valve, were necessary in 121 (92%) patients. Among 114 patients needing aortic valve/root surgery, there were 70 aortic valve-preserving procedures. Permanent neurological deficit or temporary dysfunctions occurred in 1 (0.8%) and 6 patients (4.6%), respectively. No patient suffered from paraplegia. The postoperative 30-day mortality was 2.3% (3 patients). A total of 17 patients died during the follow-up time of up to 97 months (mean 37 ± 27 months), resulting in an actuarial survival of 81.9 ± 4.3% at 5 years. No patient needed any reoperation or new intervention on the repaired aorta. CONCLUSIONS: Conventional arch surgery offers definitive repair and can be safely performed using current perfusion and operative techniques. Open procedures ensure simultaneous aortic valve repair, which is frequently necessary, and can be performed by reconstruction in more than half of the cases. The use of refined surgical and cerebral perfusion techniques allows the avoidance of deep hypothermia with all its negative side effects and leads to excellent outcomes against which the results of alternative approaches should be compared.