Sudden Death Due to Natural Causes

Preparing for the Autopsy

Whether expected or unexpected, natural sudden death is due to a catastrophic complication of a disease process or congenital malformation. As with any autopsy, the pertinent medical history of the patient should give the prosector some indication of the differential diagnosis of the lethal complication. In fact, the autopsy provides anatomic data that must be considered not only together with medical information but also in light of the social history and circumstances of the terminal event. Thus, if the available history is incomplete, the pathologist should ask for more information from a relative, other person who knew the patient well, or witness of the death. The possibility of recent signs and symptoms that might indicate a prodrome should be explored. Moreover, family history of sudden death is characteristic in certain syndromes.

Witnesses of deaths often have valuable information about the initial phase of the terminal event. In developed nations, there are increasing amounts of information available about the terminal course in many sudden deaths, even when witnessed outside the hospital: car­diopulmonary resuscitation–trained witnesses who document initial pulse and res­pirations; electrocardiograms (ECG) printed from automated external defibrillators in the field; recordings captured by pacemakers; and first-responder reports including results from ECG, oximetry, portable ultrasound, and point-of-care blood testing. Well-documented cases of cardiac arrest, that is, sudden pulselessness, are then often divided into categories depending on the initial ECG findings: (1) asystole, (2) arrhythmia, or (3) “pulseless electrical activity” (PEA; formerly called “electromechanical dissociation”) in which a heart rhythm is observed that should be producing a pulse but is not. PEA elicits a differential diagnosis that includes specific anatomic abnormalities that lead to pump failure ( Box 12-1 ), but it should be noted that many underlying causes of sudden death eventually can lead to PEA via metabolic insufficiency of the myocardium.

Even after uncovering information regarding the patient's underlying condition and terminal course, the pathologist should initiate the postmortem examination as if any cause of death is possible. There should be no restrictions on the extent of the examination. The prosector should be experienced in autopsy pathology, and it is important that objectivity be maintained. Treating the case as a mystery puts the prosector on guard for unexpected pathologic findings. As is true in general autopsy practice, the initial dissection provides the best and sometimes only opportunity to examine organs, tissues, or body fluids properly. Thus, it is imperative to have a systematic approach to this detailed examination. Such an approach has been presented elsewhere in this book (see Chapters 4 and 5 ), but adaptation of the general procedure to the specific instance of sudden death and the possibility of subtle pathologic findings remains to be discussed.

Before starting, the prosector should make certain special preparations. Interrogation of pacemakers and implantable defibrillators should be done before starting the prosection. Pictures of the exterior body surface can serve as documentation for future reference, and in infants and young children radiographs are useful for not only hidden trauma but also syndromes affecting the skeleton. Sterile syringes for cultures and vials for collection and storage of body fluids should be part of the setup in case they are needed. The pathologist should collect and store fluid and tissue samples as outlined in Chapter 10 .

The Approach to Autopsy in Cases of Sudden Death Due to Natural Causes

A list of natural causes of sudden death is given in Box 12-2 along with relative incidence of major categories in Table 12-1 . This chapter is not intended to be a complete discourse on pathologic findings in these entities; rather, it describes an approach to the problem of determining the cause of sudden death. In fact, the great majority of sudden deaths occur by a limited number of final pathogenic mechanisms—often arrhythmia, ischemia, hypoxia, or hemorrhage —but it is the task of the autopsy pathologist to identify the underlying cause of death rather than just the final mechanism by which organs are deprived of oxygen (see Box 14-3 regarding death certification). Some of these are readily apparent at autopsy, but some have to be inferred (as a diagnosis of exclusion) from the gross and microscopic pathologic findings. The following discussion assumes a certain sequence of discovery and should serve as an algorithm useful in consideration of sudden death at autopsy.