Idiopathic left ventricular tachycardia can be categorized into three subgroups based on mechanism and pharmacologic sensitivity: verapamil-sensitive, adenosine-sensitive, and propranolol-sensitive.
Recognition of the heterogeneity of ILVT mechanisms and their unique pharmacologic sensitivities facilitates appropriate diagnosis and therapy.
Idiopathic left ventricular tachycardia (ILVT) differs from idiopathic right ventricular outflow tract (RVOT) tachycardia with respect to mechanism and pharmacologic sensitivity. ILVT can be categorized into three subgroups. The most prevalent form, verapamil-sensitive intrafascicular tachycardia, originates in the region of left posterior fascicle of the left bundle. This tachycardia is adenosine insensitive, demonstrates entrainment, and is thought to be due to reentry. The tachycardia is most often ablated in the region of the posteroinferior interventricular septum. A second type of ILVT is a form analogous to adenosine-sensitive RVOT tachycardia. This tachycardia appears to originate from deep within the interventricular septum and exits from the left side of the septum. This form of VT also responds to verapamil and is thought to be due to cAMP-mediated triggered activity. A third form of ILVT is propranolol sensitive. It is neither or initiated or terminated by programmed stimulation, does not terminate with verapamil, and is transiently suppressed by adenosine, responses consistent with an automatic mechanism. Recognition of the heterogeneity of ILVT and its unique characteristics should facilitate appropriate diagnosis and therapy in this group of patients.
Lerman et al. (Thu,) conducted a review in Idiopathic left ventricular tachycardia (ILVT). Idiopathic left ventricular tachycardia can be categorized into three subgroups based on mechanism and pharmacologic sensitivity: verapamil-sensitive, adenosine-sensitive, and propranolol-sensitive.