Table 4 Echocardiographic data at 6 weeks, 3 months and 6 months follow-up Table 4.
Pannus overgrowth below the sewing ring was found in three PCU aortic valves: In one it was mild-moderate and in two it was severe causing subtotal obstruction with early sudden death. It is the first polymeric heart valve prosthesis since four decades, which is close to going into clinical studies for human long-term implantation. In gross examination the PCU valves of the long-term survivors showed mild calcification deposits preferably close to the commissures in two cases, and mild-to-moderate in one case Fig. The animals were fully heparinized perioperatively and received low molecular heparin for the first two weeks postoperatively to prevent from thromboembolic complications caused by the special anatomy of the aortic root. In addition, calves are more thrombogenic than sheep, who even tolerate mechanical valves without anticoagulation .
During in vivo testing, all animals received medical care according to the German guidelines for laboratory animal care. A total of six sheep survived to 6 months with a porcine valve implant. One trileaflet polyurethane valve demonstrated good performance in growing sheep in comparison to mechanical and biological valves . A uniform template was used. Heart valve prosthesis , Aortic valve surgery , Polyurethane , Biodegradation The first commercially available heart valve prosthesis was the Starr-Edwards mechanical valve designed for the aortic position . They were seen daily by veterinarians and examined weekly by cardiac surgeons.
The valves were checked once a week macroscopically for material degradation. Pregnancy creates a hypercoagulable state and causes an increase in haemodynamic load. In addition, calves are more thrombogenic than sheep, who even tolerate mechanical valves without anticoagulation . A total of nine sheep survived to 6 months with a mechanical valve implant. The valves were implanted orthotopic in aortic position using cardioplegic cardiac arrest with crystalloid or cold blood cardioplegia. All the porcine valve explants were affected by extensive pannus overgrowth with minor focal calcification Fig.
Therefore, major efforts were made to design a polymeric heart valve prosthesis specially for the mitral position.
Introduction Women with underlying cardiac disease are at higher risk of adverse outcomes during pregnancy than are the general obstetric population. Studies with pregnancies in women with either single or multiple prostheses were eligible for inclusion, as long as other criteria were met. Two out of ten post-operative survivors in the porcine valve group died, at 2 weeks and
The valve is kept in a specially designed holder.
Left ventricular pressure was measured directly and systolic gradients were calculated with the arterial pressure measured in the left carotid artery. Blood parameters of all animals including the long-term survivors did not show any significant changes to preoperative values in any of the animals. Both animals with commercial bioprostheses had to be sacrificed because of congestive heart failure related to structural degeneration of the bioprosthesis after 10 and 30 days of implantation. There was no destruction of the polymer integrity or the biological structure except for the described tear in one PCU leaflet.
However, there were signs of multiple myocardial infarctions in both animals with biological valves and an apical infarction area in one animal with a PCU valve.
Nevertheless, polyurethanes turned out to be superior to other polymers and newly developed polymeric heart valves proved efficacy in many assist devices, where their requirements to durability are limited .
As prespecified, 22 the strength of evidence was assessed on study design, methodological quality and the consistency of results across studies. The explanted valves underwent macroscopical, histological, radiographical and electron microscopical analysis including energy dispersive X-ray EDX spectroscopy and scanning electron microscopy. Arterial, central venous and pulmonary artery pressures were monitored continuously by an ear arterial line, a left jugular central venous line and a Swan Ganz thermodilution catheter, respectively.