The development, current status, and challenges of left atrial appendage occlusion technique

Model:Left Atrial Appendage Closure Simulator

Atrial fibrillation (AF) is the most common arrhythmia that significantly increases the risk of intra-cardiac thrombus formation. If left untreated, AF can also elevate the risk of ischemic stroke. In non-valvular AF patients, 91% to 99% of cases have the left atrial appendage (LAA) identified as the source of thrombus formation.

Oral anticoagulants are the cornerstone treatment for stroke prevention in most AF patients. However, issues such as poor compliance, increased bleeding risk, and low attainment rates pose challenges with drug anticoagulation therapy. Percutaneous LAAC is a minimally invasive procedure through catheter intervention aimed at preventing AF-related strokes.

Left atrial appendage morphology and thrombus formation

The LAA protrudes from the anterior left side of the left atrium, covering the left side of the root of the pulmonary artery and the anterior part of the left atrioventricular groove. It is a narrow blind-ended channel, a remnant of the left atrium in the late embryonic stage, shaped like a hooked long tube, varying in length from 16 to 50 mm. The LAA wall is formed by pectinate muscles with spaces between them.

There are four common morphologies of the LAA, including chicken wing, cactus, windsock, and cauliflower shapes.

Under normal circumstances, the LAA acts as an adaptive volume-regulating chamber in cases of volume overload, alleviating left atrial pressure to ensure left ventricular filling. Additionally, when left atrial pressure is abnormal, the LAA is a major source of brain natriuretic peptide (BNP) secretion to regulate and reduce circulating blood volume. However, in AF, both the morphological structure of the left atrium and LAA undergo changes, such as significantly reduced contractility of the LAA, slower intracavitary blood flow, which are often associated with secondary thrombus formation.

Statistics indicate that in non-rheumatic AF patients, around 91% of left atrial thrombi are largely related to the LAA, while in non-valvular AF patients, approximately 99% of thrombi originate from the LAA. Among these, the cauliflower shape has the highest correlation with embolic events, primarily due to the structure's internal tissue orientation, numerous leaflets with short radial axes, highly variable ostial shapes, and lack of primary leaflets.

Patient selection for LAAC: The "PARTS" principle

In selecting patients for LAAC, the "PARTS" principle should be followed:

P-Post-PCI, patients needing anticoagulation along with antiplatelet therapy post-PCI

During and after PCI, the management of anticoagulation in AF patients must balance bleeding and thrombotic risks. AF patients with concomitant coronary artery disease often require triple or dual antiplatelet/anticoagulant therapy, significantly increasing bleeding risks. For these patients, discontinuing oral anticoagulants for LAAC treatment might be a favorable option.

A-Aged, elderly patients

Elderly patients have poor compliance with anticoagulant therapy and a higher risk of bleeding, making them more likely to benefit from LAAC.

R-Renal insufficiency, patients with renal dysfunction

Previous studies have shown that patients with chronic kidney disease undergoing LAAC treatment are similarly safe and effective, especially for those prioritizing quality of life and unwilling to take warfarin, making LAAC surgery a better choice.

T-Thrombus, patients with existing thrombi in the LAA or with severe sediment-like opacification in the LAA

The greatest harm AF poses to patients is LAA thrombosis, with over 90% of non-valvular AF thrombi forming in the LAA. The pathological basis of LAA thrombosis is due to reduced LAA emptying (reduced contractility), highly associated with spontaneous opacification, blood stasis, and other factors.

S-Stroke history, patients with a history of stroke.

The Left Atrial Appendage Closure Simulator (XX013D) is a sophisticated model designed to replicate key anatomical structures involved in procedures such as left atrial appendage occlusion (LAAO), foramen ovale puncture, and pulmonary vein ablation. This simulator encompasses essential components like the femoral vein, iliac vein, inferior vena cava (IVC), right atrium, left atrium, left atrial appendage, and pulmonary vein, providing a comprehensive platform for practicing various interventional cardiology techniques. Notably, the model offers versatility with four types of replaceable left atrial appendages and three replaceable atrial septal defect (ASD) options of varying sizes, enhancing its utility for a range of procedural simulations.

Moreover, the customization services available for this simulator further elevate its value in medical training and research. Tailoring options include adjusting the location and dimensions of the ASD to match specific requirements, as well as creating personalized models based on provided data files in formats like CT scans, computer-aided design (CAD) files, and various standard 3D file formats. This flexibility in customization enables healthcare professionals, educators, and researchers to tailor simulation scenarios to their unique needs, fostering a more precise and tailored training environment for mastering complex procedures like LAA closure and other intricate cardiac interventions.