[Intraoperative electrophysiological localization of the origin of sinoatrial activity and examination of the location of the sinus node using microscope anatomic studies. Animal experiment study].
Many electrophysiological and histological investigations have demonstrated that post-operative dysrhythmias which occur in children with heart disorders requiring extensive surgical treatment in the area of the right atrium, are often caused by intraoperative lesions of the sinoatrial node. Accordingly, accurate determination of that epicardial area which is closest to the primary pacemaking area of the sinoatrial node could prevent injuries and, thus, reduce the risk of postoperative arrhythmias. To localize the relevant area we developed a method which is based on the mapping technique in a series of experiments in dogs. The electrophysiological results were confirmed by histological or gross anatomical methods. After right lateral thoracotomy in the fifth intercostal space, the epicardial surface of the right atrium is subdivided into numbered fields by means of an imaginary grid. The local electrical activities are recorded as bipolar electrograms with the aid of two tripolar electrode probes, one fixed on the epicardium of the right atrial appendage and one placed onto the individual grid fields by the investigator. Intervals thus occur between those potentials derived from the mobile electrode probe and those derived from the fixed probe. Electrical activity originating from the sinoatrial node arrives earlier at the individual fields lying closer to the node than at the field of the fixed probe at the atrial appendage. Thus, the individual field associated with the longest interval between probe potentials must lie closest to the sinoatrial node. An electronic device with digital display of the interval length has been developed which enables, within three minutes, determination of the individual field with the longest interval. Comparison of the digital values with those measured from the electrograms shows good agreement. The experiments were carried out on eleven sheep dogs and large mongrels. In seven cases the location of the sinoatrial node was determined by subsequent histological examination. The assumption that the area associated with the longest interval between the probe potentials lies closest to the primary pacemaking region of the sinus node could be confirmed, since in all these cases the cranial portion of the sinoatrial node was located in the field with the greatest interval measured. In the other four cases the sinoatrial node was localized by dissection with the aid of a stereomicroscope. In three of the four cases, the cranial part of the sinoatrial node was also situated in the field associated with the longest interval.(ABSTRACT TRUNCATED AT 400 WORDS)
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology; D002648:Child; D004285:Dogs; D004594:Electrophysiology; D006321:Heart / Q000502:physiology; D006801:Humans; D007431:Intraoperative Complications; D007432:Intraoperative Period; D012849:Sinoatrial Node / Q000033:anatomy & histology / Q000293:injuries / Q000473:pathology*
Intraoperative elektrophysiologische Lagebestimmung des sinuatrialen Erregungsursprungs und Uberprüfung der Lage des Sinusknotens durch mikroskopisch-anatomische Untersuchung. Eine tierexperimentelle Studie.