特にoverdrivesup Pressiontestの評価ならびに自然発作と誘発発作の比較

抄録

In 70 patients (26 males and 44 females) with sick sinus syndrome (SSS) who demonstrated marked sinus bradyarrhythmia, the usefulness of the overdrive suppression test (ODS) was evaluated especially through comparisons between the spontaneous cardiac arrests and those induced by the ODS.
Among the spontaneous cardiac arrests recorded by the long-term ECG, the one which had the longest pause was named the maximum spontaneous cardiac arrest (MSCA).The MSCAs ranged in length from 1.54 sec to 9.00 sec.
Patients were divided into three groups according to the lengths of MSCA and the presence of tachycardiac attacks;29 patients with MSCAs of less than 3.0 sec without any tachycardia were included in group I, 18 patients with MSCAs of 3.0 sec or more without any tachycardia in group ill, 23 patients with bradycardia-tachycardia syndrome in group III.
The ages of all the cases except only one were more than 40 years, with the mean age significantly higher in the order of group I, II and III.
The severest symptoms were seen in group X, and group II had stronger symptoms than group I.And stronger symptoms were seen in females than in males.Furthermore, cases with severe symptoms showed longer MSCAs, and the numerical values of MSCA in group III were higher than those in the other groups.
The longest RR interval among the several beats induced by the ODS was named the maximum induced cardiac arrest (MICA).In 51 of the 70 cases (72.9%), MICAs appeared immediately after the ODS, which proved identical with sinus node recovery time (SRT). When ODS is regarded as positive if SRT exceeds 130% of the PP interval immediately before the ODS, three of the 70 cases were judged as negative.When this criterion was applied to MICA, all the cases were found out to be positive, indicating MICA is more useful in making the diagnosis of SSS.
MICAs ranged in length from 1.79 sec to 8.28 sec, significantly longer in group II and than in group I.
Moreover, they were longer in the cases with stronger symptoms.It was found out as to the nature of the contractions immediately after MSCA and MICA that sinus origin was more frequent than escape in group I and II, while in group X escape after MSCA and sinus after MICA were frequent. There was a significant correlation (r=0.533, p <0.01) between MSCA and MICA.
It is concluded that the MICA provoked by the ODS greatly contributes in making the diagnosis of SSS.