Left atrial appendage occlusion (LAAO), also referred to as left atrial appendage closure (LAAC), is a treatment strategy to reduce the risk of

blood clots A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of cr ...

from the

left atrial appendage The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

entering the bloodstream and causing a

stroke A stroke is a disease, medical condition in which poor cerebral circulation, blood flow to the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorr ...

in those with non-valvular atrial fibrillation (AF). In non-valvular AF, over 90% of stroke-causing clots that come from the heart are formed in the left atrial appendage. The most common treatment for AF stroke risk is treatment with

anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where t ...

s (blood-thinners), which reduce the chance of blood clots forming. These medications (which include

warfarin Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent st ...

, and other newer approved blood thinners) are very effective in lowering the risk of stroke in AF patients. Most patients can safely take these medications for years (and even decades) without serious side effects. However, some patients find that blood thinning medications can be difficult to tolerate or are risky. Because they prevent blood clots by thinning the blood, blood thinners can increase the risk of bleeding problems. In select patients, physicians determine that an alternative to blood thinners is needed to reduce AF stroke risk. Approximately 45% of patients who are eligible for warfarin are not being treated, due to tolerance or adherence issues. This applies particularly to the elderly, although studies have indicated that they can also benefit from anticoagulants. Left atrial appendage closure is an implant-based alternative to blood thinners. Like blood thinning medications, an LAAC implant does not cure AF. A stroke can be due to factors not related to a clot traveling to the brain from the left atrium. Other causes of stroke can include high blood pressure and narrowing of the blood vessels to the brain. An LAAC implant will not prevent these other causes of stroke.

Devices and alternatives

Occlusion of the left atrial appendage can be achieved from an outside perspective (the Lariat device) or an inside (endovascular) blood exposed device (#Watchman first in this endeavor). The first method (ligation) eliminates perfusion of the LAA altogether. While effective in preventing many embolic strokes, it also negates endocrine contribution of the LAA. The second approach has many hazards as well but preserves cardiac endocrine properties of the LAA. Further evaluation of both approaches is merited. Herzohrclip - Roe pa und seitlich - Auschnitt - 001

Herzohrclip - Roe pa und seitlich - Auschnitt - 001

On March 13, 2015, the U.S. Food and Drug Administration approved the Watchman LAAC Implant, from

Boston Scientific Boston Scientific Corporation ("BSC"), incorporated in Delaware, is a biomedical/biotechnology engineering firm and multinational manufacturer of medical devices used in interventional medical specialties, including interventional radiology, i ...

, to reduce the risk of

thromboembolism Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets ...

from the left atrial appendage in patients with non-valvular AF who are at increased risk of stroke and are recommended for blood thinning medicines, are suitable for warfarin and have an appropriate reason to seek a non-drug alternative to warfarin. The Watchman implant was studied in two randomized clinical trials and several clinical registries.Watchman LAA Closure Technology – P130013
(

US Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

), April 2015. The implant was approved in Europe in 2009. The Watchman is a one-time implant typically performed under

general anesthesia General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of consciousness that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general ...

with transesophageal echo guidance (TEE). Similar to a stent procedure, the device is guided into the heart through a flexible tube (

catheter In medicine, a catheter (/ˈkæθətər/) is a thin tubing (material), tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgi ...

) inserted through the

femoral vein In the human body, the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor hiatus (an opening in the adductor magnus muscle) as the continuation of the popliteal vein. It ends a ...

in the upper leg. The implant is introduced into the

right atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

and is then passed into the

left atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

through a puncture hole.Watchman Left Atrial Appendage Closure Device with Delivery System
. 14 (

), March 2015. These small iatrogenic atrial septal defects usually disappear within six months. Once the position is confirmed, the implant is released and is left permanently fixed in the heart. The implant does not require open heart surgery and does not need to be replaced. Recovery typically takes twenty-four hours. The patient continues taking warfarin with aspirin for 45 days post implantation at which point in time they return for a

transesophageal echocardiography A transesophageal echocardiogram, or TEE (TOE in the United Kingdom and other countries such as Australia and New Zealand, reflecting the British English spelling ''transoesophageal''), is an alternative way to perform an echocardiogram. A speci ...

to judge completeness of the closure and the presence of blood clots. If the seal is complete (no gaps around the device larger than 5mm with communication to the appendage), then the patient can stop taking warfarin and start

clopidogrel Clopidogrel — sold under the brand name Plavix, among others — is an antiplatelet medication used to reduce the risk of heart disease and stroke in those at high risk. It is also used together with aspirin in heart attacks and following ...

and

aspirin Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat inc ...

for six months after implant. At six months post implantation, it is recommended for the patient to continue taking aspirin indefinitely. In the PREVAIL clinical trial, 92% of patients stopped taking warfarin after 45 days and 99% discontinued warfarin at one year. Another device termed PLAATO (percutaneous left atrial appendage transcatheter occlusion) was the first LAA occlusion device, although it is no longer being developed by its manufacturer (Appriva Medical, Inc. from

Sunnyvale, California Sunnyvale () is a city located in the Santa Clara Valley in northwest Santa Clara County in the U.S. state of California. Sunnyvale lies along the historic El Camino Real and Highway 101 and is bordered by portions of San Jose to the nor ...

). In 210 patients receiving the PLAATO device, there was an estimated 61% reduction in the calculated stroke risk. The Amplatzer device from St. Jude Medical, used to close atrial septal defects, has also been used to occlude the left atrial appendage. This can be performed without general anaesthesia and without

echocardiographic An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound of the heart. It is a type of medical imaging of the heart, using standard ultrasound or Doppler ultrasound. Echocardiography has become routinely used in th ...

guidance. Transcatheter patch obliteration of the LAA has also been reported. The ''ULTRASEAL LAA'' device, from Cardia, is a percutaneous, transcatheter device intended to prevent thrombus embolization from the left atrial appendage in patients who have non-valvular atrial fibrillation. As with all Cardia devices (such as: Atrial Septal Defect Closure Device or Patent Foramen Ovale Closure Device), the Ultraseal is fully retrievable and repositionable in the Cardia Delivery System used for deployment. The device can be retrieved and redeployed multiple times in a single procedure without replacing the device or delivery sheath. Other devices exist to occlude the

from the inside of the heart such as the Wavecrest device and the Lariat device. The latter technique entails closing a strangling noose around the LAA, which is advanced from the chest wall with a special sheath, after introducing a balloon in the LAA from the inside surface of the heart (

endocardium The endocardium is the innermost layer of tissue that lines the chambers of the heart. Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. The endocardium also provides protection to the va ...

). The LAA can also be surgically removed simultaneous with other cardiac procedures such as the maze procedure or during

mitral valve The mitral valve (), also known as the bicuspid valve or left atrioventricular valve, is one of the four heart valves. It has two cusps or flaps and lies between the left atrium and the left ventricle of the heart. The heart valves are all on ...

surgery; specifically it can be occluded or excluded by over-sewing, excision and resection, ligation, stapling with or without amputation of the LAA or application of a clip system Thorsten Hanke, "Surgical management of the left atrial appendage: a must or a myth?", ''European Journal of Cardio-Thoracic Surgery'', Volume 53, Issue suppl 1, April 2018, pp. i33–i38, Finally, the left atrial appendage has been closed in a limited number of patients using a chest keyhole surgery approach.

Adverse events

The main

adverse event An adverse event (AE) is any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An adverse event can ther ...

s related to this procedure are

pericardial effusion A pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. The pericardium is a two-part membrane surrounding the heart: the outer fibrous connective membrane and an inner two-layered serous membrane. The two layers of t ...

, incomplete LAA closure, dislodgement of the device, blood clot formation on the device requiring prolonged oral anticoagulation, and the general risks of catheter-based techniques (such as

air embolism An air embolism, also known as a gas embolism, is a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. Air can be introduced into the circulation during surgical procedures, lung over-expansion ...

). The left atrium anatomy can also preclude use of the device in some patients. Theoretical concerns surround the role of the LAA in

thirst Thirst is the craving for potable fluids, resulting in the basic instinct of animals to drinking, drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmol ...

regulation and water retention because it is an important source of

atrial natriuretic factor Atrial natriuretic peptide (ANP) or atrial natriuretic factor (ANF) is a natriuretic peptide hormone secreted from the cardiac atria that in humans is encoded by the NPPA gene. Natriuretic peptides (ANP, BNP, and CNP) are a family of hormone/pa ...

. Preserving the right atrial appendage might attenuate this effect.

Footnotes

{{Interventional cardiology Interventional cardiology Medical devices