[Value of diagnostic methods in conduction disorders for pacemaker indications and choice of a suitable stimulation...

Sinus node syndrome: In patients with sinus node dysfunction, additional conduction disturbances may be present in the AV-node thereby precluding the possibility for basically-desirable atrial stimulation. Systematic electrophysiologic studies have shown that, overall, conduction disturbances are uncommon, albeit more frequently than in normal subjects and most are incurred a high rate of stimulation. In practice, invasive electrophysiologic studies are not required to clarify this question. If there is no high-grade AV-block on Holter monitoring, diagnostic atrial stimulation can be carried out at the time of pacemaker implantation via the atrial electrode. A low rate should be used initially then increased gradually. On 1:1 conduction to 130 to 140 b/min permanent atrial pacing is possible since under these conditions it is very unlikely that high-grade AV-block will occur. If AV-block is observed at an atrial rate of 130 b/min, an additional ventricular electrode for two-chamber pacing should be implanted. If there is intact retrograde ventriculo-atrial (V-A) conduction, isolated ventricular stimulation should not be carried out because of the possibility of hemodynamically-unfavorable pacemaker syndrome. Possible problems with intact V-A conduction currently have only negligible importance since the development of modern programmable two-chamber systems. Carotid sinus syndrome: On manipulation of the hypersensitive carotid sinus, the invariably-present functional compromise of the AV-node is masked by the marked bradycardia but can be detected by atrial stimulation. This examination is not routinely necessary however, since in carotid sinus syndrome isolated atrial stimulation is not carried out.(ABSTRACT TRUNCATED AT 250 WORDS)