Clinical characteristics of hypervagotonic sinus node dysfunction.
BACKGROUND
Sinus node dysfunction (SND) is caused not only by intrinsic sinus node disease, but also by the extrinsic factors. Among the extrinsic factors, autonomic imbalance is most common. Symptomatic SND usually requires permanent pacemaker therapy. However, the clinical characteristics and patient response to medical therapy for hypervagotonic SND have not been properly clarified.


METHODS
Thirty two patients (14 men, 18 women, 51 +/- 14 years) with hypervagotonic SND were included in this study, but those patients who had taken calcium antagonists, beta-blockers or other antiarrhythmic drugs were excluded. Hypervagotonic SND was diagnosed if the abnormal electrophysiologic properties of the sinus node were normalized after the administration of atropine (0.04 mg/kg).


RESULTS
The presenting arrhythmias were 16 cases of sinus bradycardia (50.0%), 12 of sinus pause (37.5%), 3 of sinoatrial block (9.4%) and 1 of tachy-bradycardia (3.1%). Nine (28.1%) patients had hypertension, 7 (21.9%) smoked, 2 (6.3%) had diabetes mellitus, and 1 (3.1%) had hypercholesterolemia. Among the patients, 3 had no remarkable symptoms, 13 had dizziness, 7 had syncope, 3 had weakness and 6 had shortness of breath. Twenty five (78.1%) patients were treated with theophylline, 1 patient with tachy-bradycardia syndrome was treated with digoxin and propafenone, and 6 (18.8%) were treated with no medication. During the 43 +/- 28 month follow-up, 25 patients remained asymptomatic, but 6 who took no medication developed mild dizziness. One patient needed permanent pacemaker implantation owing to recurrent syncope despite of theophylline treatment.


CONCLUSIONS
These results show that hypervagotonic SND has a benign course and most of the patients can be managed safely without implanting a pacemaker. (Ed note: I like the abstract. It is short and direct, as it should be.)
Department of Internal Medicine, Division of Cardiology Chonnam National University Medical School, Gwangju, Korea.
Hyung-Wook
HW
Park
Jeong-Gwan
JG
Cho
Ju-Hyup
JH
Yum
Young-Joon
YJ
Hong
Ji-Hyun
JH
Lim
Han-Gyun
HG
Kim
Ju-Han
JH
Kim
Weon-Kim
Young-Keun
YK
Ahn
Myung-Ho
MH
Jeong
Jong-Chun
JC
Park
Jung-Chaee
JC
Kang
D004244:Dizziness / Q000209:etiology; D004417:Dyspnea / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology; D012804:Sick Sinus Syndrome / Q000150:complications* / Q000188:drug therapy; D013575:Syncope / Q000209:etiology; D013806:Theophylline / Q000627:therapeutic use; D014665:Vasodilator Agents / Q000627:therapeutic use
D014665:Vasodilator Agents; D013806:Theophylline