Since the development of cardiac monitoring, Holter ECG monitoring, His Bundle electrogram and cardiac ´pacemaker, the cardiac conduction defect has been diagnosed more precisely. Also SA block and sick sinus syndrome were well investigated recently.
Auther reviewed 10, 084 cases of electrocardiograms for recent 3years which were examined at Korea University Hospital and analyzed the incidence of conduction defect, type of SA block, conduction defect in myocardial infarction and the relation of SA and AV conduction defect and Q-Tc. There were 5390 cases-of male and 4694 cases of female with age range of 10 months to more than 80 years. In 60 cases, 24 hour Holter ECG monitoring was also carried out.
The data were as follows;
1. There were 568 cases of cardiac conduction defect out of 10, 084 cases and the incidence was 5.64% as a whole. Among the conduction defects, there was SA block in 0.36%, AV block in 2. 12% (1st degree in 1.860, Mobitz type I in 0. 11%, Mobitz type ff in 0.08%, complete block in 0.07%), bundle branek block in 2.52% (RBBB in 2.13%, LBBB in 0.39 %), interventricular conduction defect in 0.20%, left bundle hemiblock in 0.07%, bifascicular block in 0.05%, 1st degree AV block with BBB in 0. 18%, W-P-W syndrome in 0. 1%, and L-G-L syndrome in 0.04%.
2. There were 36 cases of SA block among 10.084 cases (0.36%) . In 36 cases, there were one case of Mobitz type I 2nd degree SA block, Mobitz type ff in 20 cases, no p wave. with nodal escape in 13 cases and 2 cases of transient sinus arrest associated with syncopal attack which were diagnosed by 24 hour Holter ECG monitoring.
3. There were 45 cases of conduction defect in 122 cases of acute or subacute myocardial infarction(36.9 0´). Among the 45 cases, there were 2 cases of SA block, 15 cases of 1st degree AV block, 2 cases of 2nd degree AV block, 2 cases of complete AV block, 10 cases of RBBB, 3 cases of LBBB, 4 cases of interventricular conduction defect and 7 cases of left
bundle hemiblock. These data showed low incidence of critical conduction defect. such. as Mobitz type i1 and complete AV block in Korea than in United State.
4. The Q-Tc interval were measured in 207 cases of SA block and AV block without BBB or IVCD. The values of Q-Tc in cases, of conduction defect were within normal limits. In cases of myocardial infarction, there were mild prolongation of Q-Tc interval, however there was no difference of Q-Tc interval between infarction with conduction defect and those without conduction defect. There was no relation between P-R interval prolongation and Q-Tc interval. These data suggested that the cardiac conduction defect is a specific involvement of conduction system by various causes rather than diffuse myocardial changes.
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