Catheter ablation

Catheter ablation is a procedure that uses radio-frequency energy or other sources to terminate or modify a faulty electrical pathway from sections of the heart of those who are prone to developing cardiac arrhythmias such as atrial fibrillation, atrial flutter and Wolff-Parkinson-White syndrome. If not controlled, such arrhythmias increase the risk of ventricular fibrillation and sudden cardiac arrest. The ablation procedure can be classified by energy source: radiofrequency ablation and cryoablation.

Catheter ablation
ICD-9-CM37.34
MeSHD017115

Medical uses

Catheter ablation may be recommended for a recurrent or persistent arrhythmia resulting in symptoms or other dysfunction. Typically, catheter ablation is used only when pharmacologic treatment has been ineffective.

Effectiveness

Catheter ablation of most arrhythmias has a high success rate. Success rates for WPW syndrome have been as high as 95% [1] For SVT, single procedure success is 91% to 96% (95% Confidence Interval) and multiple procedure success is 92% to 97% (95% Confidence Interval).[2] For atrial flutter, single procedure success is 88% to 95% (95% Confidence Interval) and multiple procedure success is 95% to 99% (95% Confidence Interval).[2] For automatic atrial tachycardias, the success rates are 70–90%. The potential complications include bleeding, blood clots, pericardial tamponade, and heart block, but these risks are very low, ranging from 2.6 to 3.2%.

For non-paroxysmal atrial fibrillation, a 2016 systematic review compared catheter ablation to heart rhythm drugs. After 12 months, participants receiving catheter ablation were more likely to be free of atrial fibrillation, and less likely to need cardioversion. However, the evidence quality ranged from moderate to very low[3] A 2006 study, including both paroxysmal and non-paroxysmal atrial fibrillation, found that the success rates are 28% for single procedures. Often, several procedures are needed to raise the success rate to a 70–80% range.[4] One reason for this may be that once the heart has undergone atrial remodeling as in the case of chronic atrial fibrillation patients, largely 50 and older, it is much more difficult to correct the 'bad' electrical pathways. Young people with AF with paroxysmal, or intermittent, AF therefore have an increased chance of success with an ablation since their heart has not undergone atrial remodeling yet. Several experienced teams of electrophysiologists in US heart centers claim they can achieve up to a 75% success rate.

Pulmonary vein isolation has been found to be more effective than optimized antiarrhythmic drug therapy for improving quality of life at 12 months after treatment. [5]

A 2018 study showed efficacy of cardiac ablation for treatment of Premature Ventricular Contraction as 94.1%.[6]

Technique
Electrophysiologists perform heart mapping prior to ablating the tissue causing abnormal rhythms

Catheter ablation is usually performed by an electrophysiologist (a specially trained cardiologist) in a cath lab.

Catheter ablation procedure involves advancing several flexible catheters into the patient's blood vessels, usually either in the femoral vein, internal jugular vein, or subclavian vein. The catheters are then advanced towards the heart. The catheters have electrodes at the tips that can measure the electrical signals from the heart. These electrodes create a map of the abnormal pathways causing arrhythmias. Then, the electrophysiologist uses the map to identify areas that abnormal heart rhythms originate.[7]

Once the abnormal areas are located, catheters are used to deliver energy via local heating or freezing to ablate (destroy) the abnormal tissue that is causing the arrhythmia. The energy is applied cautiously to avoid damaging healthy heart tissue.[7] Originally, a DC impulse was used to create lesions in the intra-cardiac conduction system.[8] However, due to a high incidence of complications, widespread use was never achieved. Electroporation is being used and evaluated as a means of killing very small areas of heart muscle. The cardiac catheter delivers trains of high-voltage ultra-rapid electrical pulses that form irreversible pores in cell membranes, resulting in cell death. It is thought to allow better selectivity than the previous thermal techniques, which used heat or cold to kill larger volumes of muscle.[9]

One type of catheter ablation is pulmonary vein isolation, where the ablation is done in the left atrium in the area where the 4 pulmonary veins connect.[10][11]

During the procedure, the patient's heart rhythm is monitored continuously. The electrophysiologist can observe changes to the patient's cardiac electrical activity to determine the success of the ablation. If the cardiac rhythm shows no abnormal signals or arrhythmias, the catheters are withdrawn from the heart and the incision is closed.

Recovery or rehabilitation

After catheter ablation the patients are moved to a cardiac recovery unit, intensive care unit, or cardiovascular intensive care unit where they are not allowed to move for 4–6 hours. Minimizing movement helps prevent bleeding from the site of catheter insertion. Some people have to stay overnight for observation, some need to stay much longer and others are able to go home on the same day. This all depends on the problem, the length of the operation and whether or not general anaesthetic was used.

Complications

Some potential complications associated with the procedure include:[12]

  • Bleeding - catheter insertion into arteries or veins can cause bleeding at the insertion site.
  • Blood vessel damage - insertion of the catheter can also damage the blood vessels and lead to hematoma, which is a collection of blood outside the blood vessels, or vessel perforation.
  • Infection - infections can occur at the catheter insertion site or in the heart tissue. Patients require additional treatment if infection is a complication.
  • Blood clots - catheterization can cause blood clots to form in the vessels. These clots can be thrombotic, possibly causing embolism in major organs.
  • Pericardial effusion - the ablation procedure can irritate the heart tissue and lead to accumulation of fluid under the pericardium (lining of the heart).
  • Cardiac tamponade - Similarly, if greater amounts of fluid accumulate around the heart due to irritation of the heart tissue, it can put pressure on the heart leading to tamponade. This is a serious condition as it affects the heart's ability to pump blood to the body and thus requires immediate intervention.
  • Arrhythmia - the ablation procedure can result in a new rhythm disturbance in the heart.

Patients may also experience a return of the arrhythmia after the procedure, requiring them to undergo further treatment. However, in general this procedure is considered a safe, effective, and minimally invasive method to treat arrhythmias. Studies have shown that the overall complication rate of cardiac ablation procedures is about 6%.

References
  1. Thakur RK, Klein GJ, Yee R (September 1994). "Radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome". CMAJ. 151 (6): 771–776. PMC 1337132. PMID 8087753.
  2. Spector P, Reynolds MR, Calkins H, Sondhi M, Xu Y, Martin A, et al. (September 2009). "Meta-analysis of ablation of atrial flutter and supraventricular tachycardia". The American Journal of Cardiology. 104 (5): 671–677. doi:10.1016/j.amjcard.2009.04.040. PMID 19699343.
  3. Nyong J, Amit G, Adler AJ, Owolabi OO, Perel P, Prieto-Merino D, et al. (November 2016). "Efficacy and safety of ablation for people with non-paroxysmal atrial fibrillation". The Cochrane Database of Systematic Reviews. 2016 (11): CD012088. doi:10.1002/14651858.cd012088.pub2. PMC 6464287. PMID 27871122.
  4. Cheema A, Vasamreddy CR, Dalal D, Marine JE, Dong J, Henrikson CA, et al. (April 2006). "Long-term single procedure efficacy of catheter ablation of atrial fibrillation". Journal of Interventional Cardiac Electrophysiology. 15 (3): 145–155. doi:10.1007/s10840-006-9005-9. PMID 17019636. S2CID 7846706.
  5. Blomström-Lundqvist C, Gizurarson S, Schwieler J, Jensen SM, Bergfeldt L, Kennebäck G, et al. (March 2019). "Effect of Catheter Ablation vs Antiarrhythmic Medication on Quality of Life in Patients With Atrial Fibrillation: The CAPTAF Randomized Clinical Trial". JAMA. 321 (11): 1059–1068. doi:10.1001/jama.2019.0335. PMC 6439911. PMID 30874754.
  6. Wang JS, Shen YG, Yin RP, Thapa S, Peng YP, Ji KT, et al. (August 2018). "The safety of catheter ablation for premature ventricular contractions in patients without structural heart disease". BMC Cardiovascular Disorders. 18 (1): 177. doi:10.1186/s12872-018-0913-2. PMC 6119274. PMID 30170545.
  7. Cuculich PS, Schill MR, Kashani R, Mutic S, Lang A, Cooper D, et al. (December 2017). "Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia". The New England Journal of Medicine. 377 (24): 2325–2336. doi:10.1056/NEJMoa1613773. PMC 5764179. PMID 29236642.
  8. Beazell JW, Adomian GE, Furmanski M, Tan KS (December 1982). "Experimental production of complete heart block by electrocoagulation in the closed chest dog". American Heart Journal. 104 (6): 1328–1334. doi:10.1016/0002-8703(82)90163-6. PMID 7148651.
  9. Chadi Tabaja, Arwa Younis, Ayman A. Hussein, Tyler L. Taigen, Hiroshi Nakagawa, Walid I. Saliba, Jakub Sroubek, Pasquale Santangeli, Oussama M. Wazni. https://www.sciencedirect.com/science/article/abs/pii/S2405500X2300213X JACC: Clinical Electrophysiology. In Press, Corrected Proof, Available online 21 June 2023. Catheter-Based Electroporation: A Novel Technique for Catheter Ablation of Cardiac Arrhythmias
  10. Keane D, Ruskin J (Fall 2002). "Pulmonary vein isolation for atrial fibrillation". Reviews in Cardiovascular Medicine. 3 (4): 167–175. PMID 12556750. Retrieved 22 August 2022.
  11. "Pulmonary vein isolation". Mayo Clinic. Retrieved 22 August 2022.
  12. Wyman RM, Safian RD, Portway V, Skillman JJ, McKay RG, Baim DS (December 1988). "Current complications of diagnostic and therapeutic cardiac catheterization". Journal of the American College of Cardiology. 12 (6): 1400–1406. doi:10.1016/S0735-1097(88)80002-0. PMID 2973480. S2CID 3110166.


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