Pacing for Carotid Sinus Syndrome and Sick Sinus Syndrome MICHELE BRIGNOLE,* CARL0 MENOZZI, * * GIN0 LOLLI* * , DANIELE ODDONE, * LORELLA GIANFRANCHI,* and ANTONIO BERTULLA* From the *Laboratory of Electrophysiology and Pacing Service of Cardiology, Hospital of Lavagna, Italy and the **Laboratory of Electrophysiology and Pacing Service of Cardiology, Hospital of Reggio Emilia, Italy

BRIGNOLE, M., ET AL: Pacing for Carotid Sinus Syndrome and Sick Sinus Syndrome. The real incidence of pacemaker implants for carotid sinus syndrome (CSS] and the relation between CSS and sick sinus syndrome (SSS) is not precisely known. Patients who needed pacing therapy because of atrial bradyarrhythmias were investigated by means of carotid sinus massage, dynamic ECG, and invasive electrophysiological sinus node evaluation. Of 298 consecutive patients receiving a pacemaker implant, 36 (12Yo)had a severe cardioinhibitory carotid sinus reflex with reproducible spontaneous symptoms (CSS), 33 (1 1Y0) had sinus bradycardia < 50 beatdmin or an abnormal electrophysiological evaluation (SSS) and 24 (8%) had both (CSS + SSS). The annual incidence was 40, 37, and 26, respectively, implants per year/million of inhabitants (total incidence 325). Patients affected by CSS, if compared with those affected by SSS, showed: a higher prevalence of syncope (97% vs 42%); more syncopa1,episwdes per patient (2.9 2 vs 1.8 ? 0.9); a lower prevalence of associated cardiac diseases (53% vs 100%); cardiac enlargement (36% vs 88%); heart failure (6% vs 36%) and paroxysmal atrial fibrillation (0% vs 42%); and a more frequent indication for VVI pacing (75% vs 3%). In patients with CSS + SSS, intermediate characteristics were present. In conclusion, CSS is as frequent an indication to cardiac pacing as SSS; clinical differences justify a distinction between them, even if they are associated in 26% of cases. (PACE, Vol. 13, December, Part II 1990) carotid sinus syndrome, sick sinus syndrome, permanent pacing



The real incidence of pacemaker implants for CSS and its relation to SSS are not precisely known. Data from the VIIIth World Symposium on Cardiac Pacing and Electrophysiology did not consider CSS as an independent indication to pacing; therefore it is likely that CSS patients were listed as “atrial rhythm disturbances and bradycardia” or “unknown (or other).” In this study, we analyzed the epidemiological and clinical features of our patients paced for CSS and/or SSS.

During a 20-month period in 1987-88, we implanted a permanent pacemaker in 93 consecutive patients affected by the cardioinhibitory or mixed form of CSS and/or SSS. All the patients had severe symptoms, which were intolerable or interfered with their daily activity; no other cause for symptoms could be identified. Diagnosis of CSS and SSS was made in accordance with the results of carotid sinus massage, 24 hour or more dynamic ECG and, if necessary, invasive electrophysiological study of sinus node function. CSS was considered present when the massage of carotid sinuses caused an abnormal cardioinhibitory or mixed reflex that allowed the full

Address for reprints: Michele Brignole, Via A. Grilli 164,16041 Borzonasca (GE), Italy.

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reproduction of spontaneous symptoms in different days. Right and left carotid sinuses were massaged in the erect and supine position for 10 seconds during ECG monitoring and closer manual measurements of systolic blood pressure were taken. Massage was then repeated supine and erect after intravenous administration of 0.02 mg/kg atropine to assess the contribution of the vasodepressor component (which may otherwise be hidden). The method is described fully SSS was diagnosed if the following (1) persistent diurnal at rest heart rate below 50 beatslmin (46 patients); or (2) abnormal electrophysiological study (11patients) performed when dynamic ECG revealed mild or nonpersistent bradycardia below 60 beats/min or sinoatrial block, or when chronotropic response to atropine (0.02 mg/kg IV) was inferior to 90 beatdmin. Electrophysiological study of sinus node was performed in the basal state and after autonomic blockade (propranolol 0.2 mg/kg and atropine 0.04 mg/kg). Abnormal reintrinsic heart rate insults were ferior to normal range (intrinsic rate = 118.1 (0.57 x age) ? 18%); corrected sinus node recov-

ery time > 500 msec before and > 385 msec after autonomic blockade; sinoatrial conduction time > 240 msec before and > 160 msec after autonomic blockade. Permanent pacing modalities were based on standardized criteria proposed by us's3 and by others.6-8 The VVI mode was preferred: (1)in the cardioinhibitory form of CSS without pacemaker effect; (2) in the mixed forms of CSS without pacemaker effect, ventriculoatrial conduction or orthostatic hypotension; (3) in the SSS without persistent diurnal bradycardia below 50 beatdmin. A back-up rate lower than the spontaneous one was set in order to allow the maintenance of spontaneous atrioventricular synchronism. The AAI mode was choosen for those patients affected by SSS without CSS or atrioventricular conduction disturbances; DDD mode was used for the other patients with CSS or SSS. Follow-up visits were performed 2, 4, and every 6 months thereafter. Symptoms were so identifi6d:


syncope: su'dden and unexpected loss of consciousqess;


sss+css 0thers


Figure 1. Percent indictions for pacing in 298 consecutive first implants performed, in a 20month period in 1987-88.


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alone was present in 36 cases (12%), SSS alone in 33 cases (llyo),and both were found in 24 cases (8%) (Fig. 1). Of the 60 CSS patients, 37 (62%)had the dominant cardioinhibitory form and 23 (38%)had the mixed forms. Persistent sinus bradycardia below 50 beatslmin was present in 32 of 33 patients (97%) with SSS alone but was found only in 14 of 24 patients (58%) with SSS + CSS. As our districts’ population is 550,000 inhabitants, we could estimate an annual incidence of 40 first implants per millionhnhabitants for CSS, of 37 for SSS and of 26 for CSS + SSS (Fig. 2).

severe dizziness: dizziness, sudden weakness, blurring of the vision, near syncope and confusion requiring change of posture and interfering with activity; heart failure: onset or worsening of signs and symptoms of cardiac insufficiency. Statistical Analysis The results were compared by analysis of variance, Chi-square test and Fisher’s exact test when appropriate.

Results Epidemiology

Clinical Features

A total of 293 first implants, 93 pacemakers (31%) were given to CSS or SSS patients. CSS

Patients’ main clinical features are shown in Table I. Patients affected by CSS, when compared

Table I . Clinical Features of 93 Patients Affected by CSSdand SSS

css Clinical Features


Age (years) 70.8 t 9.6 27 (75%) Males (# pts; %) Cardiac Enlargment RxiEcho ( # pts; Yo) 13 (36%) Cardiopathy -ischemic 16 (44%) -others 3 (8%) -absent 17 (47%) Paroxysmal Atrial Fibrillation (# pts; %) 0 (OYO) Symptoms Responsible for Pacemaker Implant -syncope # pts; Yo 35 (97%) # episodes/pt 2.9 t 2.0 -severe dizziness # pts; % 21 (58%) -mild dizziness # pts; Yo 27 (75%) -heart failure # pts; Yo 2 (6%) Mode of Pacing (# pts; %) -VVI 27 (75%) -AAI 0 (OYO) -DDD 9 (25%)

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+ sss


(24 P W

133 P W


70.1 2 9.2 21 (87%)

70.8 ? 7.7 22 (67%)

ns. ns.

1 5 (63%)

29 (88%)

Pacing for carotid sinus syndrome and sick sinus syndrome.

The real incidence of pacemaker implants for carotid sinus syndrome (CSS) and the relation between CSS and sick sinus syndrome (SSS) is not precisely ...
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