Advanced Bifurcation Systems' mother-daughter platform.

Description of the device and methodology The Advanced Bifurcation Systems (ABS Los Angeles, CA, USA) line of modular bifurcation systems is a novel stent platform designed to uniformly mould all coronary bifurcations regardless of angles and sizes in a simple, intuitive procedure. Orientation and alignment of main branch (mother) and side branch (daughter) segments is automatic with complete tissue coverage, evenly conforming to the anatomy without overlapping stent struts, while providing continuous side branch access. The ABS line of devices consist of a modular, dual-catheter, independently movable positioning system (currently 7 Fr) for complete multi-branch as well as provisional side branch stenting. The full bifurcation stenting system (MD-BI) consists of two balloon catheters, mother-daughter balloon catheter and daughter balloon catheter and two stents, mother-daughter stent and daughter stent. The mother-daughter balloon catheter (MDC) has a mother-daughter stent (MDS) with an aperture through which the daughter balloon catheter (DC) extrudes and leads the system. The MDS is fully circumferentially (360 degrees) crimped on the MDC, only distal to this aperture. The MDS is only partially crimped proximal to the aperture in such a fashion that the shaft of the DC can slide back and forth. In other words, the MDS is only partially longitudinally and circumferentially crimped on its delivery balloon in different segments. The daughter balloon catheter has a stent mounted only on the distal half. Additionally, the mother balloon catheter has a “sleeve” proximally through which the daughter catheter is loaded. This sleeve ensures the coaxial movement of the mother and daughter catheters. The daughter catheter leads the system by a few centimetres. A clip placed at the proximal hub of the two catheters allows for simultaneous or independent movement of the catheters. After predilatation, the system is loaded on the two wires (main and side branch wires) and advanced until it reaches the carina at which point it can not be advanced any further. The DC balloon, which now is in the daughter vessel, is pulled back, while the MDC balloon is held in place. Pull-back is completed when the proximal half of the DC is in the proximal segment of the MDS and the two proximal balloon markers are aligned next to each other. The DS, which is on the distal half of the DC balloon, is now abutting the mother stent, and a bifurcating stent is assembled on the site. The DC balloon is then inflated first, which simultaneously deploys the proximal segment of the MDS, as well as the DS, thus ensuring perfect alignment of the two stents and proper orientation of the proximal segment of the MDS. This automatic alignment is accomplished using the only fixed (non-variable) structure in any bifurcation, namely the carina. This simultaneous deployment and alignment also ensures full tissue coverage. The MDC balloon is inflated next followed by kissing inflation. The sequences of system deployment is shown in Figures 1A, 1B. The diameter sizing of the system is based on the equation governing the sizes of branching arteries according to the concept of pseudo-fractals known as the Finet’s law. This states that the diameter of a mother vessel is 0.678 times of the sum of the two daughter branches: M = 0.678 (D 1 +D 2 ). The provisional side branch stenting (MD-P) device has a shorter balloon on the DC and does not have a stent mounted on it. The deployment method is otherwise similar.