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KMID : 0377619680140060515
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Korean Jungang Medical Journal
1968 Volume.14 No. 6 p.515 ~ p.532
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An Experimental Study on Sino-Atrial Node Injury
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Abstract
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Effects on conduction system and pathological changes after sino-atrial node injuries were studied experimentally.
Twenty long term survivors out of twenty-two experimental dogs were divided into -four groups.
In each group sino-atrial node injuries were inflicted by the following methods:
Group I Crushing with hemostatic clamp.
Group II Cross ligation with 000 silk sutures.
Group III Excision of the node.
Group IV Application of 10% formalin solution.
Electrocardiographic tracing was made periodically and finally the dogs were sacrificed and specimens including the sino-atrial node were obtained for histological examination.
Following results were obtained:
1. Electrocardiographical changes
1) The heart rate was generally decreased following injury.
2) There were three cases of nodal rhythm and one case of nodal tachycardia which developed immediately following injury and converted to normal sinus rhythm gradually. In one case of excision group nodal rhythm persisted until the time of sacrifice, twenty-five days after operation.
3) Changes of the P-R interval were noted in all but two.
4) The P wave duration was prolonged in eleven cases and shortened in four.
5) The P wave voltage was depressed in general with diphasic or directional changes.
6) Changes in the P-R segment were evident in seventeen of the cases.
7) One case manifested a sudden deformed P wave during the tracing, while in three cases the deformed P wave persisted for some time, eventually being replaced by the normal P wave.
8) The appearance of a deformed P wave in most cases in which the sino-atrial node hade been either injured or excised suggests the presence of supraventricular ectopic rhythm.
2. Pathohistological findings
1) Pathohistological changes were evident in the cross ligation group,
crushing group and 10% formalin painting group, in that order.
2) In the early stages the sino-atrial node and perinodal tissue presented edema, congestion and hemorrhage, which were gradually replaced by fatty invasion, fibrosis and inflammatory exudate.
3) In three cases- one in each group I, II, and IV -cartilage formation was noted on the epicardium and myocardium.
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