Examination of the Cardiac Conduction System

Abstract

Forensic pathologists may occasionally encounter cases of apparent sudden cardiac death without gross cardiac abnormality. In some of these cases, evaluation of the cardiac conduction system may reveal pathologic lesions which may act as the substrates for ventricular tachyarrhythmias and sudden death. Sample case studies are used to illustrate the suggested criteria and techniques for examination, and commonly-encountered pathologic lesions and normal variants are discussed.

Investigation of Drowning Deaths: A Practical Review

“…Anterior neck dissection should be prompted by the finding of facial petechiae and cutaneous neck injuries in order to document any injuries of the cervical strap muscles, laryngotracheal skeleton, or hyoid bone that indicate anterolateral neck compression caused by ligature of manual strangulation. Dissection of the sinoatrial and atrioventricular nodal tissues should be performed at least for retention and otherwise for histological examination especially in an unexplained drowning such as that involving an experienced swimmer or an autopsy lacking findings of lethality (81). Retention with archival storage of heart muscle and whole blood samples are necessary in drowning deaths that are unexplained, have a decedent or family history of syncope or arrhythmia, or a family history of sudden unexplained death, in anticipation of submission for genetic analysis for cardiac channelopathies as mutations have been identified (82).…”

National Association of Medical Examiners Position Paper: Recommendations for the Definition, Investigation, Postmortem Examination, and Reporting of Deaths in Custody

“…The brain may be retained for examination by a neuropathologist if deemed necessary (11). The cardiac conduction system may be retained and evaluated by histologic examination in cases of suspected excited delirium, restraint-related deaths, or sudden cardiac deaths without grossly identified lesions (11,18). Sections of skin and subcutaneous tissue may be examined histologically to document probe wound tracks or electrical injury in cases where electronic control devices are used (1).…”

Autopsy

“…This is time-consuming, and the sampling will result in a large number of sections which will require special stains and may present a considerable workload to the laboratory technicians as well as the forensic pathologists. The process is described in handbooks of cardiac pathology, and the reader is referred to those for particulars (Gulino 2003). The macroscopic examination may reveal changes consistent with arrythmic right ventricular dysplasia, now called arrythmic right ventricular cardiomyopathy where the wall of the right ventricle has been transformed to a thin fibrous and fatty membrane, but less pronounced cases may require extensive microscopic examination to demonstrate fibrous and fatty tissue in the myocardium.…”

“…The sinus node is taken out by removing a circular section of the vena cava superior and making vertical sections through the whole specimen, making sure that the upper and lower margins of the sections are at a safe distance from the sinus node. The atrioventricular node is excised from the area limited by the coronary sinus at the far end of the membranous part of the septum, again making sure that the sections have a sufficient margin on both sides of the node (Gulino 2003). In order to locate the nodal tissues, an elastin stain will be useful in addition to routine stains.…”