Background Information

Why is there a need to improve pre-procedural planning for the left atrial appendage occlusion (LAAO) procedure with Boston Scientific's WATCHMAN device?

Left Atrial Appendage (LAA)

Location of the LAA:

Figure 1. The LAA is connected to the left atrium

Figure 2. The WATCHMAN device implanted in the LAA

Atrial Fibrillation (AFib)

Atrial fibrillation is an irregular heartbeat, an arrhythmia, that can lead to heart related complications. AFib is due to an inactive sinus node, which results in ineffective atrial contraction. As a result, blood stasis occurs inside the LAA. If blood stasis results in thrombi formation, a blood clot can enter the circulatory system and block a blood vessel. Thus, a stroke can occur.

Figure 3. AFib patients have an irregular heart beat due to the presence of abnormal impulses as a result of an inactive sinus node

Chronic Anticoagulation

Prescription of blood thinners, such as Warfarin, is the conventional method of treatment for non-valvular AFib patients in order to reduce their risk for morbidity. However, patients with systemic anticoagulation are subject to several limitations: a narrow therapeutic window, an increased risk for bleeding, a need for life-long coagulation monitoring, and having food interactions. These limitations have made prescribing the correct dosage of anticoagulants challenging. Approximately 40% of eligible AFib patients for anticoagulants do not receive this form of treatment as a result of the limitations and remain at risk for a stroke.

LAAO Procedure with the WATCHMAN Device

With limitations for AFib patients to undergo anticoagulation treatment, the LAAO procedure was developed. This procedure is a trans-catheter treatment strategy that utilizes Boston Scientific's FDA approved WATCHMAN device. The device permanently seals-off the LAA, thus offering an implant-based, non-pharmacologic alternative to blood thinners.

Overview of the steps involved in the procedure:

A flexible guide sheath is inserted into the femoral vein in the groin and threaded up to the right atrium of the heart.
A trans-septal puncture is made to cross the septum and gain access to the left atrium from the right atrium.
With the delivery system, which contains the WATCHMAN device, inserted into the guide sheath, the catheter tip is positioned at the mouth of the LAA.
With the correct positioning, the device is deployed and implanted. The appendage opening is occluded.

For more information, checkout the following videos from Boston Scientific:

Limitations with Transesophageal Echocardiography (TEE) Imaging

Currently, a TEE exam is required to determine if a patient with AFib is a candidate for the LAAO procedure. Additionally, TEE is used to determine the optimized WATCHMAN device size for that patient's unique LAA. However, due to low imaging resolution and lack of spatial visualization, physicians have difficulty in accurately identifying the unique and complex anatomy of the appendage that significantly varies per patient.

Figure 4. Various LAA shapes and sizes

Figure 5. 2D TEE imaging of the LAA

Due to the limitations with TEE images, a more patient-specific approach is needed to aid physicians in pre-procedural planning for the LAAO procedure with Boston Scientific's WATCHMAN device.

Report abuse