Outflow tract ventricular tachycardia (outflow tract ventricular premature) and its ablation treatment

  Ventricular tachycardia originating from the outflow tract, the structure where the ventricle transitions to the pulmonary artery or aorta, is called outflow tract ventricular tachycardia and is the most common form of idiopathic ventricular tachycardia, with right ventricular outflow tract ventricular tachycardia being the most common. Exercise and mood changes often trigger episodes of right ventricular outflow tract ventricular tachycardia. Patients with interictal sinus rhythm are often accompanied by ventricular tachycardia of the same pattern as ventricular tachycardia. The diagnosis is usually made immediately on the basis of the ECG at the time of the attack. A rapid intravenous infusion of adenosine can terminate right ventricular outflow tract ventricular tachycardia, so this type of ventricular tachycardia is also known as adenosine-sensitive ventricular tachycardia. Long-term pharmacological treatment of right ventricular outflow tract ventricular tachycardia includes verapamil, thiazepam, and beta-blockers. Ablation may be considered for patients who fail to take medications or who do not want to take them.  Ventricular tachycardia can be induced intraoperatively by rapid manual stimulation with ventricular electrodes, but some patients may require a combination of myocardial stimulants to induce ventricular tachycardia. Spontaneous ventricular tachycardia or premature ventricular tachycardia may also be targeted for ablation if ventricular tachycardia is frequent or if frequent episodes are consistent with a ventricular tachycardia pattern. Whether ventricular tachycardia is induced manually or spontaneous ventricular tachycardia or premature ventricular tachycardia is used as a target, ventricular stimulation is required to attempt to induce ventricular tachycardia before the end of ablation, with the treatment endpoint of no longer being able to induce ventricular tachycardia. Both agitated and paced labeling are the most common methods of finding ablation targets for right ventricular outflow tract ventricular tachycardia ablation. The overall success rate of right ventricular outflow tract ventricular tachycardia ablation is 85-90%.  It is usually possible to distinguish between left or right ventricular outflow tract ventricular tachycardia by body surface ECG, but in some cases it is more difficult to identify, and ablation of both left and right outflow tracts may need to be attempted. The special feature of left-sided outflow tract ablation is that the ablation site is closer to the coronary artery, and to avoid injury to the coronary artery, coronary angiography is often required to confirm the location of the coronary opening before ablation. Correspondingly, coronary occlusion is a rare complication of left ventricular outflow tract ventricular tachycardia ablation.  Premature outflow tract beats are also more common in the right ventricular outflow tract. The ablation principle and procedure of outflow tract premature beats is essentially the same as that of outflow tract ventricular tachycardia, which can be understood, to some extent, as a succession of outflow tract premature beats. Ablation of outflow tract premature ventricular contractions is a more stringent indication than that of outflow tract ventricular tachycardia, and the possibility of ablation is generally considered only when the total number of 24-hour ventricular premature contractions is 20,000 or more.