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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1976-8-2
pubmed:abstractText
Sino-atrial conduction time (SACT) may be calculated from the difference between the length of the return cycle and the spontaneous cycle, using programmed premature atrial stimulation during spontaneous sinus rhythm. This approach to sinoatrial conduction assumes that sinus node automaticity is not changed by premature depolarization. In order to validate this assumption, we compared the length of the post-return cycles to the spontaneous cycle length in 71 patients. Patients were grouped according to clinical diagnosis and the value of calculated SACT. At long coupling intervals at which no reset of the sinus node occurred there was only a small prolongation of the post-return cycles (less than 8.4 msec, on an average) compared to the spontaneous cycle length. This suggests no or only an insignificant effect of premature depolarization on the sinus node. However, during test stimuli leading to reset of the sinus node, the post-return cycles were significantly prolonged between 20 to 30 msec, on an average. The response of the individual cases sometimes varied to a great extent. In patients who demonstrated a progressive linear prolongation of the return cycles at decremental shortening of the test interval, there was no significant prolongation of the post-return cycles versus the spontaneous cycle length. We conclude that 1) premature depolarization of the sinus node may have a depressant effect on sinus node automaticity, which, if present, is usually small; 2) calculation of SACT using the extrastimulus technique may overestimate true SACT.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0009-7322
pubmed:author
pubmed:issnType
Print
pubmed:volume
53
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
920-5
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
The effect of premature atrial depolarization on sinus node automaticity in man.
pubmed:publicationType
Journal Article