Introduction
Cardiac arrhythmia refers to an irregular heartbeat. If an arrhythmia is present, the heart may beat faster or slower and not function properly. Various reasons can cause arrhythmias, and the treatment depends on the underlying cause. Cardiac ablation is one of the procedures to treat arrhythmias, and it can be a catheter or surgical ablation. Cardiac catheter ablation uses a tube to destroy the areas of tissues that are causing arrhythmias.
What Is Cardiac Catheter Ablation?
Ablation is a procedure that destroys abnormal tissue and restores the heart's function. Cardiac catheter ablation is also referred to as radiofrequency ablation. It is a minimally invasive procedure and first-line therapy for tachycardias. It is not performed in all patients with arrhythmias. It is indicated if medications fail to control the arrhythmias and for certain types of arrhythmias associated with the upper chambers of the heart. It is also indicated for arrhythmias in Wolff-Parkinson-White syndrome and supraventricular tachycardia. It has evolved to become the first-line treatment for patients with recurrent symptoms of arrhythmia.
What Are the Equipment Used in Catheter Ablation?
The following types of equipment are used during catheter ablation:
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Catheters - Catheters with ring electrodes are used for bipolar stimulation and recording.
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Junction Box - It is a rectangular box that receives the intracardiac signals sent from the catheters.
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Recording Apparatus - The recorder records, displays, and stores intracardiac recordings.
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Stimulator - A stimulator obtains the electrophysiological data beyond conduction interval measurements.
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Defibrillator - Defibrillation pads are attached to the patients to deliver energy in a biphasic waveform.
How Is a Catheter Ablation Performed?
Cardiac catheter ablation is performed in an electrophysiology laboratory, and it takes two to four hours. Before the procedure, complete blood count, renal functions, liver functions, and coagulation profile are checked. Intravenous medication is given before the procedure to help the patient relax and fall asleep. An area in the groin region is anesthetized, and a small hole is made in the skin. The doctor then places three or four long thin, flexible tubes (catheters) in the blood vessels to reach the heart. The catheter may be inserted into a large vein or artery in the groin or into the vein in the arm or the neck.
After placing the catheters, the electrodes at the end of the catheters help stimulate the heart and locate the tissues that are causing abnormal heartbeats. A contrast dye is injected into the catheter to visualize the blood vessels clearly on an X-ray. The doctor then uses radiofrequency hot or cold energy to destroy those tissues. Once the abnormal tissue is ablated, abnormal electrical signals are not sent to the heart, thereby preventing arrhythmias. The guide wires and the catheters are removed after the procedure, and pressure is applied at the site of insertion to decrease the bleeding. Later, Aspirin or other blood thinners are prescribed to prevent the formation of blood clots.
What Are the Types of Catheter Ablation?
Cardiac catheter ablation uses hot or cold energy to destroy abnormal heart tissue. It includes the following:
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Radiofrequency Ablation: In this, radiofrequency heat energy is used to destroy the heart tissue.
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Cryoablation: In this procedure, cold energy is used to freeze and scar the abnormal heart tissue.
What Are the Indications of Catheter Ablation?
Cardiac catheter ablation is used to treat all types of rapid arrhythmias. It is recommended by the cardiologist if medications cannot treat abnormal heart rhythms. It is indicated in the following arrhythmias:
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Atrial Fibrillation and Atrial Flutter: The heartbeat is rapid and irregular in atrial fibrillation and atrial flutter. It causes the atria (upper chambers of the heart) to beat irregularly. Ineffective contractions prevent the pumping of blood through the heart and increase the risk of stroke as blood becomes pooled in the left atrium.
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Supraventricular Tachycardia: The heartbeat is irregular and fast, up to 300 beats per minute in supraventricular tachycardia. Though the heart pumps blood normally, long-standing supraventricular tachycardia can damage the heart.
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Ventricular Tachycardia: In ventricular tachycardia, the lower chambers of the heart (ventricles) beat faster and independently, resulting in cardiac arrest.
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Ventricular Fibrillation: The heartbeat is ineffective and irregular in ventricular fibrillation.
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Cardiac Arrest: Catheter ablation is recommended if sudden cardiac arrest occurs.
What Are the Contraindications of Catheter Ablation?
Cardiac catheter ablation does not have any absolute contraindications. It includes the following relative contraindications:
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The presence of deep vein thrombosis (DVT) is contraindicated in femoral vein access. Peripheral arterial disease (PAD) and aortic dissection are contraindicated in the retrograde aortic approach.
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It is contraindicated if an intracardiac thrombus is present to prevent the risk of embolization.
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Catheter ablation is contraindicated in the presence of bleeding diathesis and coagulopathy.
What Are the Complications Associated With Catheter Ablation?
The complications depend on the site of ablation and the type of cardiac arrhythmia. It includes the following:
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Catheter ablation can cause myocardial infarction, stroke, and death in some cases. However, the risk of stroke is higher in curative atrial fibrillation ablation.
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Heart block is one of the complications of catheter ablation. And it depends on the proximity of the lesion to the atrioventricular node.
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Cardiac trauma and perforation are other complications that result in cardiac tamponade.
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Catheter ablation can cause thromboembolic complications such as systemic and venous embolism.
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The risk of thromboembolic events is common in atrial-esophageal fistula due to the increased time of ablation.
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It can cause aneurysms, arteriovenous fistula, and retroperitoneal bleeding depending on the site of access.
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Complications like phrenic nerve damage and pulmonary vein stenosis can occur in atrial fibrillation ablation. However, pulmonary vein stenosis and atrial-esophageal fistula are rare complications.
Conclusion
Cardiac catheter ablation is the mainstay treatment for several types of arrhythmias, and it has a higher success rate. It remains the best choice for the symptomatic accessory pathway, atrial fibrillation, atrial flutter, drug-refractory ventricular tachycardia, and premature ventricular contractions-induced cardiomyopathy. Catheter ablation is a painless, minimally invasive procedure. It is also associated with various complications, such as pulmonary vein stenosis, esophageal perforation, vascular access complications, phrenic nerve injury, heart block that requires a pacemaker, and death. However, it offers a 90 percent success rate in the treatment of arrhythmias.
