EComment. Extra-anatomic aortic valve bypass

Abstract

We have read with interest the report by Domoto and colleagues [1]. Extra-anatomic aortic valve bypass (or apico-aortic conduit) has been adapted to selected high risk patients as an alternative to conventional aortic valve replacement and is based on the experimental work of Alexis Carrel [1–3]. In May 1910, Alexis Carrel (1873–1944) presented his work on experimental surgery of the thoracic aorta and the heart to the American Surgical Association [3]. Notably, at this time, cardiac surgery was limited to the treatment of penetrating wounds of the heart [3]. The poor results of thoracic surgery in the laboratory and in the theatre motivated Carrel to begin experiments with the hope of improving, or finding new surgical methods for the treatment of vascular and valvular diseases of the heart and aneurysms of the thoracic aorta [3]. In an attempt to develop a technique of diverting the blood, whilst avoiding neurological complications, for the treatment of aneurysms of the thoracic aorta, he described both central and lateral diversion of the blood. Lateral diversion consisted of an anastomosis between the left ventricle and the descending aorta through a paraffined rubber tube or a jugular vein (preserved in cold storage) [3]. These experiments were carried out at the Rockefeller Institute for Medical Research, in New York, and he was awarded the Nobel Prize in Medicine in 1912 (the first one of its kind in USA). In 1955, Sarnoff et al. developed the apico-aortic conduit concept further and were able to direct the entire cardiac output from the left ventricle to the thoracic aorta (in animals), using a Hufnagel valve in a lucite tube and permanently occluding the ascending aorta [4]. In 1975, Cooley reported on the 1962–1963 experience of Templeton who implanted Sarnoff's prosthesis in five patients with one 10 year long-term survivor, and Cooley further popularised the apico-aortic conduit procedure [5]. Indications for aortic valve bypass surgery, apart from those reported by Domoto et al., include patients with previous complex cardiac operations (Cabrol and homograft/root replacements) that preclude a safe re-sternotomy, sternal wound infection, regional radiotherapy, failed aortic annular augmentation procedures and patients with complex congenital LV outflow obstruction [1,2]. Specific complications include bleeding, thrombus formation in the aorta, hence the need for anticoagulation or antiplatelet treatment, as well as formation of pseudo-aneurysm or dehiscence from the LV apex in a number of patients [1,2]. Today, with the advent of transcatheter aortic valve implantation (TAVI), the need for the more invasive apico-aortic conduit approach has significantly diminished, but still remains an option for a few complex patients in whom TAVI is not an option. Conflict of interest: none declared.