Pitfalls in Pacemaker Implant for Hypersensitivity of the Carotid Sinus

Syncope is the cause of 3% and 1% of emergency and hospital admissions, respectively [1-4]. It is the final common pathway of a host of different pathophysiological mechanisms [5]. Accurate diagnosis of the mechanism of syncope is essential for adequate management and prognosis in individual cases. Prior to the introduction of the head-up tilt table test (HUTT) in clinical practice, most cases of syncope remained undiagnosed. The routine use of the HUTT has shown that reflex syncope comprises the most frequent mechanism underpinning those cases theretofore diagnosed as “syncope of undetermined origin” [6,7]. Reflex syncope is currently classified as (i) vasovagal (the common faint), (ii) situational (cough, micturition, laugh, defecation, and (iii) carotid sinus syndrome (CSS) [8]. CSS is said to be present when the loss of consciousness is elicited in response to accidental mechanical manipulation of the carotid sinus region. It can be reproduced in the lab through carotid sinus massage (CSM) [9]. Carotid sinus hypersensitivity (CSH) represents a ventricular pause >3 seconds and/or a fall in systolic blood pressure >50 mmHg after CSM. The CSS is a rare condition, accounting for only 1% of patients with syncope in most clinical series [10]. CSS is most common in elderly men [11]. It also constitutes one important mechanism underlying cases of unexplained falls in the elderly [12].