Circulating microemboli after composite replacement or valve-sparing aortic root surgery

Microemboli in aortic valve replacement

Microembolic signals (MES) can be detected in many recipients of mechanical aortic valve prostheses by transcranial Doppler ultrasound. The nature and etiology of these MES have remained unclear for a long time. The solid and gaseous nature of MES are discussed, as well as whether or not MES may reflect artifacts. Recently, the gaseous nature of these MES has been widely established. To understand the physics of bubble formation related to mechanical heart valve prostheses, it is necessary to discuss the different types of cavitation occurring at the prostheses and the conditions leading to the degassing of blood. We describe the history of transcranial Doppler ultrasound-techniques and the current techniques in the measurement of these signals. Furthermore, the possible clinical impact of MES, as well as strategies for the design of new prostheses and surgical alternatives to diminish their load are discussed.

Restitution of the Aortic Valve: What is New, What is Proven, and What is Obsolete?

Restitution strategies of the insufficient aortic valve belong to the clinical armamentarium. To date, the accumulated body of evidence comprises 126 articles dealing with restitution strategies on the insufficient aortic valve with concomitant aortic surgery. In a cumulative analysis an almost identical number of reimplantation (506) and remodeling (489) procedures were found in the literature, whereas 357 patients underwent aortic valve resuspension. The cumulative results tend to favor the reimplantation technique in terms of longevity of the reconstruction, particularly in congenital degenerative disorders of the aortic wall, whereas remodeling appears to exhibit a more physiologic behavior of the reconstructed valve and re-suspension serves as a simplified approach particularly in acute type A dissection. Although restitution of the native aortic valve has its place in current treatment options, the accumulated worldwide numbers indicate that it is not yet routinely implemented in the vast majority of cardiac institutions.

Recurrent aortic dissection in Marfan's syndrome: possible effects of anticoagulation

Recent reports support the role of a valve-sparing procedure in ascending aortic dissection in patients with Marfans syndrome. A 49-year-old woman with Marfans syndrome and prior aortic aneurysm repaired with a composite graft presented with sudden-onset chest pain. Following an initial negative computed tomographic (CT) scan, a long dissection involving the descending thoracic and abdominal aorta was discovered on a repeat CT scan a few hours later. Symptoms improved gradually with optimal medical management and the patient was discharged home on anticoagulant therapy. Although no direct cause-and-effect relationship can be established, chronic anticoagulant therapy may accelerate the progression of recurrent dissection in these patients. A valve-sparing procedure should be considered in eligible patients with Marfans syndrome who need operative correction to avoid possible future untoward effects of long-term anticoagulant therapy.