What Is Alcohol Septal Ablation?

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Alcohol Septal Ablation (ASA) is a non-surgical procedure typically used to treat cases of hypertrophic obstructive cardiomyopathy (HOCM).1 First reported by Sigwart in 1985, its use has since grown exponentially, with the procedure now used widely for the treatment of H0CM.2 In ASA, alcohol is used to shrink enlarged heart tissue, restoring adequate blood supply and relieving symptoms associated with HOCM.1 Within this article we will discuss the basis of HCM, the process of ASA, and the risks and complications associated with ASA. 

Understanding hypertrophic obstructive cardiomyopathy (HOCM) 

Our hearts consist of four chambers. The top two are referred to as the ‘atria’ and the bottom two are referred to as the ventricles. Dividing these ventricles is a structure known as the septum. Think of it as being similar to the septum that separates your two nostrils. In the case of the heart, however, this structure is muscular. In HOCM (the most common type of hypertrophic cardiomyopathy), the walls of the ventricles or the muscular septum itself can thicken abnormally.1 Whilst muscle growth within the body is usually a good thing, septal growth can have significantly negative effects. For example, this growing septum may bulge into the left ventricle, partially obstructing the flow of blood out of the ventricle and into the main artery (the aorta).1 This blockage places extra strain on the heart forcing it to work harder to push blood out into the body. This blockage causes additional pressure to accumulate within the ventricle, placing extra stress on the septum and ventricles. Just like any other muscle in the body, increased work will cause it to grow and become stronger. However, the growth of either the ventricles or septum can cause this condition to worsen, resulting in the development of more severe symptoms such as fatigue and breathlessness. To reduce this blockage and to improve symptoms, alcohol septal ablation (ASA) is typically used. 

Details of the procedure 

Preparing for ASA 

It is important to discuss with your healthcare provider how you can prepare for ASA. Typically, they will want to know if you are on any particular medications, as they may advise you to stop these before the procedure. Examples of these medications include beta-blockers. You will also be told that you should not eat or drink anything after midnight on the day before your procedure. Your healthcare provider is also likely to perform the following tests before undertaking the procedure:

The process of alcohol septal ablation (ASA)

ASA is a minimally invasive procedure, meaning smaller incisions are made and recovery time is often shorter. The process usually takes 1-2 hours depending on the severity of the case. General anesthesia is not required for the procedure and you will be awake throughout. The following steps of ASA are typically performed:1

  1. The team performing the procedure may give you medicines to help you relax. 
  2. You will also likely be given aspirin or heparin (blood thinners). This is to reduce the chance of blood clots forming during the procedure. 
  3. The area around the groin may need to be shaved. A local anaesthetic will then be administered to numb the area before a small incision is made. 
  4. The doctor will then insert a thin, flexible tube known as a catheter into an artery or vein within your groin. 
  5. The catheter will then be threaded through the blood vessels until it reaches the heart. 
  6. The doctor will likely use angiography and contrast echocardiogram to guide the catheter and to ensure it is in the right place. 
  7. A small amount of alcohol is released into the artery that supplies blood to the septum. As alcohol is toxic, this causes some of the cells to shrink and die. This may be accompanied by an uncomfortable sensation. 
  8. Measurements of the pressures within your heart will then be taken to ensure an improvement can be observed. 
  9. The catheter will be removed through the groin. 
  10. The team will then close and bandage the site where the catheter was inserted. 

Risks and complications of alcohol septal ablation (ASA)

ASA has significant benefits, with studies showing that 98.6% of patients live for at least 5 years without any heart-related issues following the procedure.3 Despite this, it is important to note that the procedure is not without any associated risks. These risks have been identified and recorded as the following:1 

Heart block has been identified as one of the most common complications of ASA. This is where there is a disruption to the electrical signals that travel through the heart, often resulting in a slow heartbeat. Treatment usually requires the insertion of a permanent pacemaker. If tears occur during the surgery, open-heart surgery may be required

You are at greater risk of experiencing these complications if you are older or have other heart problems.1 It is important to note, however, that hospitals that specialise in ASA have the lowest rate of complications.1

After the procedure 

After the procedure, you can expect the following to occur:1

  • You will spend several hours in a recovery room. 
  • During this time, your vital signs will be monitored. Particular attention will be paid to your heart rate and breathing. 
  • An echocardiogram may be performed after the surgery to assess the septum and left ventricle. This will allow your healthcare provider to assess how successful the procedure was and to assess for any immediate complications. 
  • To prevent bleeding, you will need to lie flat for several hours after the procedure. You should also avoid bending your legs during this time. 
  • You will likely be prescribed anticoagulants to prevent blood clots after the procedure. 
  • You will also be likely given pain medicine. 
  • It is also likely that you will spend between one and three days in the intensive cardiac care unit for monitoring. 
  • If a heart block develops, you will need to have a permanent pacemaker fitted. 


Alcohol Septal Ablation (ASA) is a minimally invasive procedure used commonly to treat hypertrophic obstructive cardiomyopathy (HOCM), a type of hypertrophic cardiomyopathy (HCM). In patients with this condition, the septum that divides the two lower chambers of the heart (the ventricles) can become enlarged. This can then bulge into the left ventricle, partially obstructing the flow of blood and causing the symptoms of HOCM such as breathlessness and fatigue. To treat this, healthcare professionals typically rely on the use of ASA. Before undergoing this treatment, however, it is important to discuss the procedure with your doctor so that they can assess your suitability and give appropriate advice. Before the procedure, you should avoid eating or drinking and may be advised to stop certain medications. Imaging tests and blood tests may also be conducted before the procedure. During the procedure, a catheter will be inserted through the blood vessels into the groin and threaded through to the artery that supplies the septum with blood. Your doctor will then administer small amounts of alcohol to kill these cells and improve blood flow. You will not require general anaesthesia for this procedure and will be awake throughout. There are some complications associated with ASA, although they are rare. Heart block is the most common, and if this occurs, a permanent pacemaker will need to be fitted. Following the procedure, you will be given anticoagulants to prevent the development of blood clots. You will also be closely monitored for up to 3 days to assess for any complications that may arise. 


When should I call my doctor if I am worried I am experiencing complications? 

If you develop any of the following symptoms, it is important that you contact your healthcare provider4: 

  • Abnormal pulse, heart rate, or palpitations. 
  • Pain in the chest. 
  • Difficulty breathing, shortness of breath, or rapid breathing. 
  • Dizziness or lightheadedness. 
  • Fatigue
  • Fever, redness or swelling at the incision site (signs of infection)
  • Nausea and vomiting. 


  1. Alcohol Septal Ablation [Internet]. 2019 [cited 2023 Dec 8]. Available from: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/alcohol-septal-ablation.
  2. Sigwart U. Non-surgical myocardial reduction for hypertrophic obstructive cardiomyopathy. Lancet. 1995; 346(8969):211–4.
  3. Batzner A, Pfeiffer B, Neugebauer A, Aicha D, Blank C, Seggewiss H. Survival After Alcohol Septal Ablation in Patients With Hypertrophic Obstructive Cardiomyopathy. J Am Coll Cardiol. 2018; 72(24):3087–94.
  4. Alcohol Septal Ablation: Procedure and Outlook. Cleveland Clinic [Internet]. [cited 2023 Dec 8]. Available from: https://my.clevelandclinic.org/health/treatments/22498-alcohol-septal-ablation.

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Morgan Keogh

MBBS, Medicine, King's College London, UK

I am a fourth year Medical Student at Kings College London, currently intercalating in a BSc in Cardiovascular Medicine. I have a strong interest in Cardiology, Acute Internal Medicine and Critical Care. I have also undertaken a research project within the field of Cardiology whereby I explored the efficacy of a novel therapeutic test at detecting correlations between established clinical characteristics and salt-sensitive hypertension. I have broad experience with both the clinical and theoretical aspects of medicine, having engaged with a wide array of medical specialities throughout my training. I am currently acting as a radiology representative within the Breast Medicine Society and have experience with tutoring at both GCSE and A-level. I am also working closely alongside medical education platforms to ensure the delivery of content applicable to the learning of future doctors.

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