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What is a Left Atrial Appendage?

The left atrial appendage (LAA) is a small, pouch-like structure in the left atrium of the heart. The LAA acts as a contractile reservoir and a decompression chamber.

In normal hearts, the LAA plays a role in regulating blood volume by storing and releasing hormones called atrial natriuretic peptides. It produces approximately 30% of ANPs, which are released in response to stretch, helping regulate blood volume and pressure. Due to its anatomical position and greater ability to swell compared to the main left atrium, it can act as a decompression chamber during periods of increased left atrial pressure, thereby reducing stress on the atrial walls.

As a contractile reservoir, it aids the movement of blood from the left atrium to the left ventricle. During atrial systole, the LAA empties into the left ventricle and assists with filling the left ventricle during late diastole. This contraction helps prevent blood from pooling and stagnating, which leads to the formation of blood clots.

(Naksuk et al., 2016)

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What is the Relationship Between Atrial Fibrillation and the LAA?

In patients with atrial fibrillation, blood tends to pool in this pouch because their atria do not contract normally. This stagnant blood increases the risk of forming blood clots in the left atrial appendage, which can then travel to the brain and cause a stroke (Naksuk et al., 2016).

“Atrial fibrillation is associated with a 4- to 5-fold increased risk of ischemic stroke and accounts for 25% of the 700,000 cerebrovascular accidents that occur in the United States annually” (Saw et al., 2023).

Aorta

Left atrium in fibrillation

Site of clot formation in LAA

Left Ventricle

Ischemic Stroke

Stroke

Blood clot (thrombus) blocking blood flow

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There are Four Main Morphologies of the LAA:

“Cactus”

Dominant central lobe with extending secondary lobes
~30% of patients

“Windsock”

Dominant lobe larger than the distal portions
~19% of patients

“Cauliflower”

No dominant lobe but has more complex characteristics than other morphologies
~3% of patients

“Chicken Wing”

Presents an obvious bend in the proximal or middle part of the dominant lobe
May fold back on itself, which can be a secondary lobe or twist
~48% of patients

CACTUS CHICKEN WING CAULIFLOWER WINDSOCK

(Beigel et al., 2014)

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LAA Ostium Facts:

LAA Ostium Location in Relation to Left Superior Pulmonary Vein (LSPV):

•Same level as LSPV (60-65% of patients)

•Superior to LSPV (25-30% of patients)

•Inferior to LSPV (5-15% of patients)

LAA Ostium Shape:

•Elliptical (most common)

•Round

•Triangular

•Water drop-like

•Foot-like

LAA Ostium Size:

•Width 12.1 – 38.8 mm

•Length 24.9 – 85.7 mm

•Depth 16-51 mm

Ostium Position:

•Type I: The LAA ostium is located superior and anterior to the LSPV, separated by a wide lateral ridge.

•Type II: The most posterior part of the LAA ostium is very close to a thinner, more prominent lateral ridge.

•Type III: The LAA ostium is positioned at the level of the LIPV.

(Dudkiewicz et al., 2021; Regazzoli et al. 2015)

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What is LAAO/LAAC?

The left atrial appendage (LAA) closure is a medical procedure used to reduce the risk of stroke in patients with atrial fibrillation. This procedure is especially beneficial to those patients who are unable to take long-term blood thinners. Closure or occlusion techniques can be surgical or percutaneous. Surgical techniques include excision, suture closure, and clip-based closure. Percutaneous techniques are minimally invasive and include devices such as Watchman, Amulet, and Lariat (suture delivery device).

For patients who meet the criteria for this procedure, a special implant made of metal alloy is put into the LAA. Over time, tissue grows over the implant and seals off the LAA, preventing stagnant blood from pooling in this area and forming a clot that can move to the brain. This procedure will lower the risk of stroke in patients with atrial fibrillation that is not caused by mitral valve disease.

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What are the Pre-Procedure Requirements?

Pre-Anesthesia Assessment:

Baseline labs, including type and screen
Pre-anesthesia questionnaire

Pre-procedure TEE or Cardiac CT scan:

LAAO procedural planning
Clot detection
Assessing LAA anatomy
Assistance in guiding the procedure
Identify potential complications that may arise

Shared Decision Form:

Ensures that this is a safe and effective alternative to oral anticoagulant therapy for stroke prophylaxis

Pre-Procedure Assessment and Eligibility Form:

CHA2DS2-VASc Score ≥3

Calculates stroke risk in patients with atrial fibrillation

HAS-BLED Score – minimum of 1

Hypertension, Abnormal liver/renal, Stroke, Bleeding, Labile INRs, Elderly (>65), Drugs or ETOH

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How is a Percutaneous LAAO Performed?

PREPARATION:

Antibiotic prophylaxis
General Anesthesia, Monitored Anesthesia Care (MAC), or Moderate Sedation (dependent on your facility and if TEE is being utilized)
Transesophageal echocardiogram (TEE) and/or intracardiac ultrasound (ICE)
Supplies:

Trans-septal access system
0.035” Guide Wire with extra support (i.e., Amplatz Super Stiff)
Pigtail catheter
Contrast dye and heparin
Two 60 cc syringes for device prep
Pressurized heparinized saline with a manifold
Device supplies

PROCEDURE:

Femoral vein access (two venous accesses if MD using 4D intra-cardiac ultrasound vs. TEE)
Evaluation of the LAA confirming ostium size and absence of cardiac thrombus
Documentation of the pericardial space
Administration of heparin with repeat ACT testing (≥250)
Trans-septal access to position the device into the LAA
Obtain LA pressure (if < 10 mmHg, consider IVF bolus)

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POSITIONING THE DEVICE:

Contrast dye and imaging are used for determining the location and obtaining measurements of the LAA
Imaging is also used to confirm placement. If satisfied, the device is deployed and remains in its designated location.
PASS Criteria: Position, Anchor (Stability), Size (compression range 10-30%), and Seal (absence of gaps/leaks; all lobes are covered)

ACCESS SITE MANAGEMENT:

Figure 8 stitch with manual compression or vascular closure devices
Monitor for hematoma and/or bleeding

(Image from Research Gate)

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4D Intracardiac Echo:

Some physicians may opt to use 4D ICE vs. TEE for device delivery and deployment.

4D ICE can eliminate the need for TEE due to its advanced imaging. TEEs are used to determine if a clot is present before proceeding and to determine device size and placement.

4D ICE enhances visualization for clot detection and precise device placement.

(ADAMS ET AL., 2024; FRANGIEH, A.H. ET AL., 2017)

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Risks and Benefits of Having This Procedure:

RISKS:

Pericardial effusion/ tamponade
Bleeding
Stroke or systemic embolism
Device embolization (dislodges into the heart or vessels – rare)
Access site complications
Device-related thrombus (DRT)
Peri-device leak (incomplete sealing)
Poor healing leading to continued use of anticoagulation medications
Reactions to anesthesia

BENEFITS:

Reduced risk of stroke
Alternative to long-term blood thinners
One-time procedure
Improved quality of life

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Post-Procedure Care:

Typically, after completion of the procedure, the patient will be transported to recovery for continuous cardiac monitoring, vital signs monitoring, and groin site management. Dependent on physician preference, some patients may be able to be discharged home the same day. Discharge is determined by pre-, intra-, and post-procedure events, as well as patient medical history and needs.

Access Site Management:

All patient will have a bed rest period. Access site should be monitored for tenderness, swelling, and bleeding. Patients will typically have some bruising and mild soreness at the access site. Most patients can shower within 24-48 hours post procedure by gently using soap and water. Patients should avoid scrubbing the area and avoid soaking for one week. This means no baths, swimming, or hot tubs.

Neuro Assessments:

Neuro assessments should be performed pre- and post-procedure and continued throughout their hospital stay. While LAAO interventions are highly effective at preventing thromboembolic events originating from the left atrial appendage, patients remain vulnerable to thromboembolic events not originating from the appendage.

Complication Monitoring:

Patients will be monitored for complications such as bleeding, pain, changes in mental status, and difficulty breathing. Think about the potential complications of this procedure and how your patient will present with such.

Discharge Instructions and Patient Education:

Patients should seek medical attention if they experience a fever greater than 100*F or higher, chest pain/pressure, syncope, dizziness, diaphoresis, and/or nausea/vomiting. Patients should be educated on how to apply direct pressure to the sight if bleeding occurs and to seek immediate medical attention if bleeding continues for more than ten minutes or if the site has redness, warmth, drainage, or swelling. Patients will have activity restrictions including no heavy lifting (greater than ten pounds), strenuous exercise, and/or intense physical activity for one week. Patients can resume light activities and increase activity as tolerated. Please educate patients to avoid driving for 24-48 hours. Patients should be provided with education on follow-up appointments (see next slide) and their medication regimen.

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Follow-Up: Aligned with NCDR LAAO Registry

The patients will be sent home, and most will continue taking their anticoagulation medications. Patients will have a 1 - 2 week, 45-day, 6-month, 1-year, and 2-year follow-up.

45-Day Follow-Up:

A TEE or CT scan is performed to check for device stability, ensure heart tissue has begun to cover the device, and to check that there is no leak
Typically, patients are transitioned off their anticoagulation medications and transitioned to dual antiplatelet therapy (DAPT). Usually, this is aspirin and clopidogrel.

6-Month Follow-Up:

This may include another TEE or CT scan to confirm device stability, continued healing, and to ensure there is no thrombus formation.
If the patient does not have any complications, they are typically transitioned to aspirin alone for long-term prevention.

1-Year Follow-Up:

Not always required, but there may be a follow-up TEE or CT scan.
Patients are evaluated for stroke risk, bleeding risk, arrhythmia control, and overall health.
Most patients are only on aspirin at this point.

2-Year Follow-Up and Beyond:

Focus is on long-term stroke prevention and atrial fibrillation management.
Patients are also checked for late device-related issues, which are rare.
Typically, patients are on aspirin indefinitely unless otherwise indicated.

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Resources:

Adams, A., Mahmood, R., Balaji, N., Dixit, P., Chandra, S., & Weisman, D. (2024). Real-world experience utilizing the nuvision 4D intracardiac echocardiography catheter for left atrial appendage closure. Scientific reports, 14(1), 11937. https://doi.org/10.1038/s41598-024-60692-5

Alkhouli, M., Ellis, C.R., Daniels, M., Coylewright, M., Nielsen-Kudsk, J.E., & Homes, D.R. (2022). Left atrial appendage occlusion: current advances and remaining challenges. JACC: Advances, 1(5). https://www.jacc.org/doi/10.1016/j.jacadv.2022.100136

Beigel, R., Wunderlich, N.C., Ho, S.Y., Arsanjani, R., & Siegel, R.J. (2014). The left atrial appendage: anatomy, function, and noninvasive evaluation. JACC: Cardiovascular Imaging, 7(12). 1251-1265. https://doi.org/10.1016/j.jcmg.2014.08.009.

Dudkiewicz, D., Słodowska, K., Jasińska, K.A., Dobrzynski, H., & Hołda, M.K. (2021). The clinical anatomy of the left atrial structures used as landmarks in ablation of arrhythmogenic substrates and cardiac invasive procedures. Translational Research in Anatomy, 23. https://doi.org/10.1016/j.tria.2020.100102

Frangieh, A. H., Alibegovic, J., Templin, C., Gaemperli, O., Obeid, S., Manka, R., Holy, E. W., Maier, W., Lüscher, T. F., & Binder, R. K. (2017). Intracardiac versus transesophageal echocardiography for left atrial appendage occlusion with watchman. Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions, 90(2), 331–338. https://doi.org/10.1002/ccd.26805

Naksuk, N., Padmanabhan, D., Yogeswaran, V., Asirvatham, S.J. (2016). Left atrial appendage: embryology, anatomy, physiology, arrhythmia and therapeutic intervention.

JACC: Clinical Electrophysiology, 2(4). 403-412. https://doi.org/10.1016/j.jacep.2016.06.006.

Regazzoli, D., Ancona, F., Trevisi, N., Guarracini, F., Radinovic, A., Oppizzi, M., Agricola, E., Marzi, A., Sora, N. C., Della Bella, P., & Mazzone, P. (2015). Left Atrial Appendage: Physiology, Pathology, and Role as a Therapeutic Target. BioMed research international, 2015, 205013. https://doi.org/10.1155/2015/205013

Saw, J., Holmes, D.R., Cavalcante, J. L., Turi, Z.G., Wand, D.D., Whisenant, B.K., Freeman, J.V., Goldsweig, A.M., Kavinsky, C.J., Moussa, I.D., Munger, T.M., Price, M.J., & Reisman, M. (2023). SCAI/HRS Expert Consensus Statement on Transcatheter Left Atrial Appendage Closure. Journal of the society of cardiovascular angiography & interventions, 2(3). https://doi.org/10.1016/j.jscai.2022.100577

Shimada, M., Akaishi, M., & Kobayashi, T. (2020). Left atrial appendage morphology and cardiac function in patients with sinus rhythm. Journal of echocardiography, 18, 117-124. https://link.springer.com/article/10.1007/s12574-020-00462-0

Walter, M. (2022). Older LAAO patients, especially women, face a higher risk of complications. Cardiovascular Business Structural Heart Disease. https://cardiovascularbusiness.com/topics/clinical/structural-heart-disease/older-laao-patients-especially-women-face-higher-risk

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