What is Alcohol Septal Ablation (ASA)?
Alcohol septal ablation is a percutaneous procedure performed to treat hypertrophic cardiomyopathy. Hypertrophic cardiomyopathy (HCM) is a genetic disorder characterized by abnormal thickening of the heart muscle, known as myocardium. HCM predominantly affects the ventricular septum. The ventricular septum is the muscle which separates the two ventricles. Hypertrophic cardiomyopathy is usually inherited. It is caused by a change in some of the genes in heart muscle proteins. High blood pressure or aging can also lead to development of HCM. Diseases such as diabetes or thyroid disease can cause hypertrophic cardiomyopathy as well.
Indications for Alcohol Septal Ablation
- Symptomatic patients with NYHA (New York Heart Association) class III-IV
- Drug resistant angina
- Resting LVOT (Left Ventricular Outflow Tract) gradient > or equal to 40 mmHg
- Provoked LVOT gradient > or equal to 60 mmHg if resting gradient < 40 mmHg
- Basal septal thickness >15mmHg
Alcohol septal ablation procedure was first introduced in 1994 by Dr. Ulrich Sigwart as a less invasive alternative to surgical septal myectomy. Originally targeted to a population of symptomatic patients, this technique was used on patients who were thought to be poor surgical candidates. Several technical refinements have since been done for this technique like introduction of myocardial contrast echocardiographic localization of the targeted area.
Who is a Candidate for Alcohol Septal Ablation?
Alcohol septal ablation is a minimally invasive procedure which is recommended for patients who are not ideal candidates for surgery. This might include patients who are older or have other diseases that might make open-heart surgery or its recovery difficult. Alcohol septal ablation might also be appropriate for patients who after understanding the risks and benefits of both treatment options, strongly prefer to avoid an open heart surgery.
What Happens Prior to the Alcohol Septal Ablation Procedure?
Before the Alcohol septal ablation procedure, you and your records which include echocardiogram, angiogram, etc. are evaluated by a cardiologist in their office. You are informed about the risks, benefits, and treatment options. A direct conversation will help you and your physician decide which procedure is best for you.
How is Alcohol Septal Ablation Procedure Done?
The basic steps involved in alcohol septal ablation are as follows:
The procedure is performed in a cardiac catheterization laboratory. A sedative is administered for relaxation and pain relief. The cardiac activity of the patient is monitored during and after the procedure through transesophageal echocardiography. Electrodes are placed on the chest to monitor the heart rate during the procedure. Tubes are inserted into the artery and vein in your groin, and a temporary pacemaker is passed through the venous system to the right ventricle of the heart. A guidewire and balloon catheter are inserted through the tube and moved to your heart. Position of the septal artery is identified by employing a dye test, and then balloon catheter is inserted to that region. The position of the balloon is confirmed by ECG and the balloon is inflated to temporarily block the septal artery. Alcohol (100%) 2 to 5 cc is injected, causing the muscle cells in the area to shrink or die. Finally, the balloon is deflated and removed from the septal artery.
How Does Alcohol Septal Ablation Work?
The alcohol directly damages the thickened muscle causing necrosis. The heart muscle dies i.e. a heart attack occurs which leads to thinning of the septum. This allows the heart to function more efficiently, with less leakage of the mitral valve. The results could be immediate and they continue to improve over the following six months.
Postoperative Care Following Alcohol Septal Ablation Procedure
Generally, this procedure requires 3-5 days of stay at the hospital. The basic post-operative instructions are as follows:
After the procedure, the patient is taken to the coronary care unit (CCU) where vital signs like heart rate and breathing are monitored.
The team may perform an ECG after the procedure to view the ventricle and let the healthcare provider depict how successful was the ablation. You will be asked to lie flat without bending your legs to prevent bleeding. The healthcare provider may prescribe some anticoagulants to keep your blood from clotting. The patient may also be prescribed pain medicines if required. If the patient has a heart rhythm problem, he/she may have a permanent pacemaker placed.
Limitations of Alcohol Septal Ablation Procedure
Alcohol septal ablation is a very safe and effective procedure. Some limitations and side effects of ASA are as follows:
Alcohol septal ablation is not considered medically necessary for members who are asymptomatic with normal exercise tolerance or whose symptoms are controlled or minimized on optimal medical therapy.
Other limitations are lack of accuracy in targeting the specified area can cause obstruction, lack of ability to handle additional cardiac lesions, may cause right bundle-branch block, may produce complete heart block (that requires permanent pacemaker), serious ventricular arrhythmias etc.
Risks of Alcohol Septal Ablation Procedure
Risks of the procedure include death during or after hospitalization, heart damage or heart attack in other areas of the heart, severe lung damage, rhythm problems requiring a permanent pacer, a defibrillator or medical therapy, stroke, bleeding, need for transfusion, kidney failure or damage leading to temporary or permanent dialysis, vascular damage requiring surgery, cardiac damage or bleeding requiring surgery, contrast or drug allergy, and other risks. Your specific risks are discussed with you during your initial visit. An electrophysiological evaluation may be necessary before or after the alcohol ablation. You may require surgery for placement of a permanent pacemaker or an implantable defibrillator. So ideally only severely symptomatic patients are selected for this beneficial but potentially risky procedure.
What is the Follow Up Course Like?
After discharge, you are asked to return for cardiology office follow-up. Repeat echocardiography is performed at the six-month visit. The patient must discuss symptoms like slow heart rate, fainting spells, severe shortness of breath, fever, chills, or right-groin pain. This will help the physician to assess how well did the ablation go and help him prevent any further possible complications.
Various studies have shown that patients with mildly symptomatic hypertrophic cardiomyopathy (obstructive) have shown significant symptomatic and hemodynamic relief with a low risk for severe heart failure. Their survival can be compared to general population and most of them achieve long‐term functional class NYHA I and LVOT gradient ≤30 mm Hg.