Analysis of shear stress related hemolysis in a ventricular assist device.

BACKGROUND: Implantable devices such as ventricular assist devices provide appropriate treatment for patients with advanced heart failure. Unfortunately, these devices still have many problems, particularly related to blood damage. OBJECTIVE: The aim of this research is to examine two new ventricular assist devices in terms of induced shear stress, exposure time, and induced hemolysis. METHOD: Reverse engineering was used on multiple axial flow ventricular assist devices to collect all the details related to the designs (diameters, lengths, blade angles…), which were used to build two prototypes: Model A and Model B. RESULTS: The obtained results were close to a large extent, except for static pressure rise, where the difference was clear. CONCLUSION: Compared with what has been published in other studies, the overall performance of both models was excellent.

Numerical study of a new ventricular assist device.

The present work presents a numerical study of two axial ventricular assist devices (VADs) with two different designs. The geometry of the first design was inspired by DeBakey's rotary blood pump and the geometry of the second design is based on BioCirc's pediatric VAD. The goal is to see which of the two designs has promising capabilities in terms of pressure differential, flow rate, and thrombosis before proceeding to deeper investigations. In this study a computational fluid dynamics tool was used to simulate and calculate the hemodynamics in the two investigated models. Both models were investigated for a flow rate of 5 L/min at rotational speeds between 10 000 and 15 000 rpm.

Endovascular treatment of a tuberculous thoracoabdominal aneurysm with the Multilayer stent.

PURPOSE: To describe a case of multiple thoracoabdominal aneurysms of tuberculous origin treated in an endovascular procedure with the Multilayer stent. CASE REPORT: A 16-year-old girl had been treated 4 years previously for a ruptured abdominal aortic aneurysm of tuberculous origin. Due to the presence of 4 rapidly evolving saccular aneurysms of the descending thoracic aorta and a fusiform aneurysm of the suprarenal aorta, an endovascular solution was chosen after the patient refused open surgery. Three uncovered Multilayer stents (16×40, 16×80, and 16×80 mm) were successively implanted with a 1-cm overlap from the left subclavian artery to cover the entire aneurysmal segment of the thoracoabdominal aorta to above the renal arteries. At 18 months, serial imaging studies have shown disappearance of some aneurysms and regression of others. CONCLUSION: In this young patient, the endovascular treatment of a thoracoabdominal aneurysm with an uncovered stent made it possible to stabilize the aneurysm process without exposing the patient to the high morbidity and mortality of open surgery.

Use of magnetic resonance imaging in assessment of constrictive pericarditis: a Moroccan center experience.

BACKGROUND: The diagnosis of constrictive pericarditis continues to be a clinical challenge. Magnetic resonance imaging provides excellent visualization of the pericardium. The aim of our study is to clarify the contribution of this non invasive exploration in the diagnosis of constrictive pericarditis in our center. METHODS: we conducted a prospective study over a period of two years, since 2008, covering a series of patients (n = 11), mean age 44 ± 15 years, in whom constrictive pericarditis was suspected clinically and on transthoracic echocardiography. We studied its characteristics on magnetic resonance imaging. RESULTS: Magnetic resonance imaging confirmed the diagnosis showing pericardial thickening in all cases, measuring 8.2 +/- 2.6 mm on average, circumferential in 64%, and localized in 36%. The imaging data, particularly pericardial thickening and its topography, were confirmed by surgical exploration, and results were concordant in all cases. CONCLUSION: Magnetic resonance imaging is a powerful tool to establish constrictive pericarditis diagnosis.

Novel point mutation in the NKX2-5 gene in a Moroccan family with atrioventricular conduction disturbance and an atrial septal defect in the oval fossa.

Defects of the oval fossa usually occur as isolated malformations, but can show an autosomal dominant pedigree in familial cases. Several mutations have been described for the transcription factor NKX2-5, and co-segregate with varied cardiac anomalies. We have identified by sequence analysis a novel missense heterozygous mutation in the NKX2-5 gene, specifically a substitution of glutamine for proline at codon 160, in a Moroccan family, the affected members having a deficiency of the floor of the oval fossa and atrioventricular block.

The incomplete ring with modulated flexibility: a new concept of mitral annuloplasty.

Among the different techniques of mitral valve repair (involving chordea, commissures, papillary muscles, leaflets, or annulus), the annuloplasty remains a difficult problem-solving step. Since invention of the first ring, which was rigid and closed, the concept of annuloplasty has taken into consideration the following objectives: to make the available leaflet tissue well fitted to the systolic mitral orifice by repairing the length and shape of the dilated annulus, prevent its further dilatation, and provide a support to the fragile area after a partial leaflet resection.