STANFORD B DISSECTION, ITS CLASSIFICATION, PATHOPHYSIOLOGY, RISK FACTORS, DIAGNOSIS AND TREATMENT OF IT

Abstract

The aorta is the largest blood vessel in the body that starts from the left ventricle of the heart and extends to the abdomen where it divides into two common iliac arteries. Some of the more common problems affecting the aorta include aneurysm (a weak bulge in the aorta) which can occur in the aortic root, ascending, descending and abdominal aorta, penetrating aortic ulcer (fatty build up plaques that break down the tissue of the inner lining of the aorta) aorta to reach the middle layer), aortic dissection (tear in the inner lining of the aorta causing blood to seep between the middle and inner layer), ruptured aorta (tear that extends through all layers of the aortic wall tissue).
Aortic dissection is one of the most devastating vascular challenges facing interventional physicians, frequently misdiagnosed and often associated with catastrophic outcomes. Stanford type B aortic dissections affect the descending thoracic aorta without any involvement of the ascending aorta and are associated with high mortality and morbidity requiring immediate or delayed treatment either surgically, endovascularly, or with hybrid techniques. This comprehensive article addresses the current status of pathophysiology, classification of aortic dissection, risk factors for Stanford type B dissection, its diagnosis, and state of the art treatment either through open, endovascular, and hybrid procedures with a focus on new therapeutic perspectives.
Dissections associated with refractory pain, rapid aneurysm formation, malperfusion syndromes, rupture, or impending rupture are categorized as complicated and distinguished from initially uncomplicated type B dissections in which the above complications do not exist. All type B dissections require prompt medical treatment to prevent aortic rupture. Acute complicated dissections are nowadays treated with endografting to divert blood flow into the true lumen and promote false lumen thrombosis and future aortic remodeling to limit mortality, while uncomplicated type B dissection is managed medically.
During the last two decades, thoracic endovascular aortic repair (TEVAR) has emerged as an alternative to open surgical repair for the treatment of complicated type B dissection. Various societal guidelines now unanimously suggest TEVAR as the treatment of choice for the management of complicated disease based on its relatively low morbidity and mortality compared with open surgical outcomes. As a consensus recognized standard of care for the management of patients with complicated lesions, TEVAR is currently being considered for select patients with initially uncomplicated dissection to mitigate the risks of mid and late term disease progression and aortic related mortality. This article describes the decision making treatment algorithm for the management of type B aortic dissection. It also provides a comprehensive review of the indications and procedural recommendations for implementing TEVAR based on current evidence in the literature. In addition, the article guides readers through step by step practical considerations, from selecting the optimal graft to ensuring its ideal placement in a type B dissection, as well as providing advice on how to manage various complications associated with the procedure.
In chronic dissection with aneurysm formation of the descending thoracic and/or thoracoabdominal aorta, especially in connective tissue disorders, open surgery nowadays offers the best immediate results with long durability. Thoracic endografting plays only a minor role in these circumstances, but branching and circumscribed endografting are very promising techniques. Hybrid techniques can offer a solution for high risk patients who are not suitable for open surgery. Open surgery is limited for chronic aneurysms after dissection. Monitoring of the aorta is of paramount importance in all situations.