9. “My surgeon wants to close off my LAA during my Mini-Maze surgery. Should I agree? What’s the role of the Left Atrial Appendage?”
The Left Atrial Appendage (LAA) is a pocket or sleeve-like structure on the outside left top of the left atrium which opens into the left atrium. It’s a complicated structure with often more than one lobe. From an embryonic perspective, the LAA is more related to the ventricles than to the smooth-walled atrium.
In the first trimester or two of our time in the womb, The Left Atrial Appendage (LAA) was originally our left atrium (LA). When the final real Left Atrium (LA) formed gradually from the conjunction and evolutionary development of the four pulmonary veins, the actual LA chamber grew and ballooned out, pushing the smaller remnant LA up to the left top of the Left Atrium where it became known as the Left Atrial Appendage (LAA) with its own functions and behaviors. But as we age and as heart disease/A-Fib, etc. start to set in, the LAA can turn into “the most lethal, no longer essential appendage in the human anatomy.” (Thanks to Shannon Dickson for these insights about the LAA.)
Sometimes during a difficult A-Fib catheter ablation case (persistent or long-standing persistent), the LAA has to be partially or completely electrically isolated from the rest of the heart. When the LAA is ablated, there is a 70% chance of significantly reducing its emptying volume. If the LAA emptying volume is reduced to less than 40 millileters/sec, the patient would have to be put on blood thinners for life or their LAA would have to be removed or closed off. Otherwise clots would form in the LAA because of low blood flow.
Functions of the Left Atrial Appendage
- The Left Atrial Appendage functions like a reservoir or decompression chamber or a surge tank on a hot water heater to prevent surges of blood in the left atrium when the mitral valve is closed. Without it there is increased pressure on the pulmonary veins and left atrium which might possibly lead to heart problems later.
- Cutting out or stapling shut the LAA reduces the amount of blood pumped by the heart and may result in exercise intolerance for people with an active life style. (In dogs the LAA provides 17.2% volume of blood pumped.)
- The LAA also has a high concentration of Atrial Natriuretic Factor (ANF) granules which help to reduce blood pressure. The LAA functions as a storage device for ANF. But recent preliminary research indicates that the Right Atrial Appendage compensates for the loss of the LAA by producing more ANF.
- The Left Atrial Appendage may also function as a reservoir of different types of stem cells which can stimulate the heart to repair itself (See
Left Atrial Appendage May be Important for Heart Repair http://a-fib.com/laa-important-for-heart-health-repair/
The LAA, Blood Clots and Stroke Risk: In A-Fib, blood stagnates in the LAA and clots tend to form. By closing off the Left Atrial Appendage, most but not all risk of stroke is eliminated even if you are still in A-Fib.
On the other hand, cutting out or stapling shut the LAA also reduces the amount of blood pumped by the heart and may result in exercise intolerance for people with an active life style.
One considered advantage of the Mini-Maze operations is that the Left Atrial Appendage (LAA) is routinely closed off.
The Controversy: Some question the need or benefit of removing the Left Atrial Appendage (LAA) if someone is no longer in A-Fib. For a patient made A-Fib free, would their heart function better or more normally if they still had their LAA?