Anatomy of the first septal perforating artery: A study with implications for ablation therapy for hypertrophic cardiomyopathy

Objective: To determine the variability in the size and distribution of the first septal perforating artery (FSPA). Material and Methods: In this pilot study, 10 fresh autopsy hearts from pat ients who did not have hypertrophic cardiomyopathy (HCM) or clinical eviden ce of coronary artery disease were evaluated for the variability in the siz e of the FSPA. The size of the FSPA was also measured during coronary angio graphy in 8 patients with HCM who were undergoing alcohol septal ablation. Results: Of the 10 autopsy hearts, 2 had a large FSPA (greater than or equa l to1.0 mm in maximal diameter) with prominent septa] myocardial distributi on, 2 had a medium-sized FSPA (0.5-0.9 mm), 2 had a small FSPA (0.1-0.4 mm) , 3 had a tiny FSPA (<0.1 mm), and 1 had an indiscernible ostium. In 2 pati ents the FSPA supplied the right ventricular free wall. In 4 patients the b asal ventricular septum was incompletely supplied by the FSPA. Of the 8 pat ients with HCM, the FSPA was larger than 2 mm in diameter in 2 patients, 1 to 2 mm in 4, and smaller than 1 mm in 2. The distance between the left ant erior descending coronary artery ostium and the origin of the FSPA ranged b etween 13.1 and 37.4 mm, indicating a large variation in the size and distr ibution of the FSPA. Conclusions: Variability in the size and distribution of the FSPA in patien ts without HCM was substantial. Areas of the heart other than the basal sep tum were supplied in some patients by the FSPA. In other patients the FSPA did not supply the entire basal septum. Similar findings were noted in pati ents with HCM. A detailed evaluation of the distribution of the FSPA may be necessary in all patients with HCM who are undergoing alcohol septa] ablat ion.