Crib death: further support for the concept of fatal cardiac electrical instability as the final common pathway

Autopsy for Medical Diagnostics: Finding the Cause of Sudden Unexpected Death through Investigation of the Cardiac Conduction System by Serial Sections

Sudden unexpected death (SUD) is a fatal event that occurs in an apparently healthy subject in a way that such an abrupt outcome could have not been predicted. SUD-including sudden intrauterine unexplained death (SIUD), sudden neonatal unexpected death (SNUD), sudden infant death syndrome (SIDS), sudden unexpected death of the young (SUDY), and sudden unexpected death in the adult (SUDA)-occurs as the first manifestation of an unknown underlying disease or within a few hours of the presentation of a disease. SUD is a major unsolved, shocking form of death that occurs frequently and can happen at any time without warning. For each case of SUD, a review of clinical history data and performance of a complete autopsy, particularly focused on the study of the cardiac conduction system, were carried out according to the necropsy protocol devised by the Lino Rossi Research Center, Università degli Studi di Milano, Italy. Research cases collected and selected for this study were represented by 75 SUD victims that were subdivided into 15 SIUD, 15 SNUD, 15 SUDY, and 15 SUDA victims. After a routine autopsy and clinical history analysis, death remained unexplained, and hence a diagnosis of SUD was assigned to 75 subjects, which included 45 females (60%) and 30 (40%) males ranging in age from 27 gestational weeks to 76 years. Serial sections of the cardiac conduction system disclosed frequent congenital alterations of the cardiac conduction system in fetuses and infants. An age-related significant difference in distribution among the five age-related groups was detected for the following anomalies of the conduction system: central fibrous body (CFB) islands of conduction tissue, fetal dispersion, resorptive degeneration, Mahaim fiber, CFB cartilaginous meta-hyperplasia, His bundle septation, sino-atrial node (SAN) artery fibromuscular thickening, atrio-ventricular junction hypoplasia, intramural right bundle branch, and SAN hypoplasia. The results are useful for understanding the cause of death for all SUD cases that were unexpected and would have otherwise remained unexplained, so as to motivate medical examiners and pathologists to perform more in-depth studies.

Sudden Unexpected Death Associated with Arrhythmogenic Cardiomyopathy: Study of the Cardiac Conduction System

A retrospective study was conducted on pathologically diagnosed arrhythmogenic cardiomyopathy (ACM) from consecutive cases over the past 34 years (n = 1109). The anatomo-pathological analyses were performed on 23 hearts diagnosed as ACM (2.07%) from a series of 1109 suspected cases, while histopathological data of cardiac conduction system (CCS) were available for 15 out of 23 cases. The CCS was removed in two blocks, containing the following structures: Sino-atrial node (SAN), atrio-ventricular junction (AVJ) including the atrio-ventricular node (AVN), the His bundle (HB), the bifurcation (BIF), the left bundle branch (LBB) and the right bundle branch (RBB). The ACM cases consisted of 20 (86.96%) sudden unexpected cardiac death (SUCD) and 3 (13.04%) native explanted hearts; 16 (69.56%) were males and 7 (30.44%) were females, ranging in age from 5 to 65 (mean age ± SD, 36.13 ± 16.06) years. The following anomalies of the CCS, displayed as percentages of the 15 ACM SUCD cases in which the CCS has been fully analyzed, have been detected: Hypoplasia of SAN (80%) and/or AVJ (86.67%) due to fatty-fibrous involvement, AVJ dispersion and/or septation (46.67%), central fibrous body (CFB) hypoplasia (33.33%), fibromuscular dysplasia of SAN (20%) and/or AVN (26.67%) arteries, hemorrhage and infarct-like lesions of CCS (13.33%), islands of conduction tissue in CFB (13.33%), Mahaim fibers (13.33%), LBB block by fibrosis (13.33%), AVN tongue (13.33%), HB duplicity (6.67%%), CFB cartilaginous meta-hyperplasia (6.67%), and right sided HB (6.67%). Arrhythmias are the hallmark of ACM, not only from the fatty-fibrous disruption of the ventricular myocardium that accounts for reentrant ventricular tachycardia, but also from the fatty-fibrous involvement of CCS itself. Future research should focus on application of these knowledge on CCS anomalies to be added to diagnostic criteria or at least to be useful to detect the patients with higher sudden death risks.

In utero exposure to nicotine abolishes the postnatal response of the cardiac sodium current to isoproterenol in newborn rabbit atrium

BACKGROUND

In utero exposure to tobacco smoke is associated with sudden infant death syndrome (SIDS) and cardiac arrhythmias in newborns. The arrhythmogenic mechanisms seem linked to alterations of the cardiac sodium current (I_Na). We previously reported that in utero exposure to nicotine delays the postnatal development of the heart sinoatrial node in rabbits and altered expression of the sodium channels Na_V1.5 and Na_V1.1 in the atrium surrounding it. These channels react differently to sympathetic stimulation.

OBJECTIVE

The purpose of this study was to test whether nicotine altered the response of I_Na to stimulation by the β-adrenoreceptor agonist isoproterenol in atrial myocytes. Our hypothesis is that changes in the sympathetic response of sinoatrial node peripheral cells may create a substrate for arrhythmia.

METHODS

Using the patch-clamp technique we measured the effect of nicotine on the response of I_Na to adrenergic stimulation in isolated cardiomyocytes.

RESULTS

Isoproterenol increased I_Na by 50% in newborn sham rabbits but had no effect in newborn rabbits exposed to nicotine in utero. Our data also show that nicotine increases the late sodium current, an effect that may promote QT prolongation.

CONCLUSION

We provide the first evidence linking fetal exposure to nicotine to long-term alterations of I_Na response to isoproterenol. These changes may impair I_Na adaptation to sympathetic tone and prevent awakening from sleep apnea, thus leading to arrhythmias that could potentially be involved in SIDS. Our data also raise concerns about the use of nicotine replacement therapies for pregnant women.

Pathology of unexpected sudden cardiac death: Obstructive sleep apnea is part of the challenge

Unexpected sudden cardiac death (SCD), sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death (SIUD) are major unsolved, devastating forms of death that occur frequently. Obstructive sleep apnea (OSA) has been associated with increased cardiovascular and cerebrovascular morbidity and mortality, including sudden cardiac death (SCD). This editorial will review the pathology of SCD, including sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death (SIUD); OSA with its cardiovascular consequences; the possible link between SCD and OSA, discussing the potential mechanisms underlying these two frequent, but yet overlooked pathologies. Finally, the possible preventive benefits of treating OSA and identifying patients at common risk for OSA and SCD and SIDS-SIUD to prevent unexpected deaths will be discussed. Post-mortem examination is of great importance in every case of SCD sine materia, with examination of the brainstem and cardiac conduction system on serial sections, when general autopsy fails, but it should be stressed that also the investigations of patients suffering from OSA should focus on the possibility of pathological findings in common with cases of SCD.

Right Ventricular Involution: Big Changes in Small Hearts

BACKGROUND

Before birth, the fetal right ventricle (RV) is the pump for the systemic circulation and is about as thick as the left ventricle (LV). After birth, the RV becomes the pump for the lower pressure pulmonary circulation, and the RV chamber elongates without change in its wall thickness. We hypothesize that the fetal RV may be a model of compensated RV hypertrophy, and understanding this process may aid in discovering therapeutic strategies for RV failure.

METHODS

We performed a literature review and identified pertinent articles from 1980 to present.

RESULTS

The following topics were identified to be most pertinent in right ventricular involution: morphologic and histologic changes of the RV, cellular proliferation and terminal differentiation, the effect of stress on RV development, excitation contraction coupling and inotropic response change over time, and the amount of apoptosis through RV development.

CONCLUSIONS

The RV changes on multiple levels after its transition from systemic to pulmonary circulation. Although published literature has variable results due partly from differences between animal models, the literature shows a clear need for more research in the field.

Right ventricular involution: What can we learn from nature's model of compensated hypertrophy?

BACKGROUND

Right ventricular (RV) failure (RVF) is a vexing problem facing patients with various disease processes and carries a high mortality. RVF is a poorly understood phenomenon with limited treatment options. In mammalian fetal circulation, the right ventricle is the systemic ventricle. In neonates, however, the left ventricle assumes that role and gradually thickens compared with the right ventricle. This process, known as right ventricular involution (RVI), is poorly understood. We sought to define the time course and identify mechanisms involved in RVI.

METHODS

Wild-type mice were bred and sacrificed on day of life (DOL) 1, 4, 8, 16, and 30 to evaluate left ventricular (LV) and RV wall thickness and apoptosis. A terminal deoxynucleotidyl transferase nick-end labeling assay and RNA sequencing were performed to measure changes during RVI.

RESULTS

Morphometric analysis demonstrated the changes in RV and LV wall thickness occurring between DOL 1 and DOL 16 (RV:LV, 0.53:0.44; P = .03). In addition, apoptosis was most active early, with the highest percentage of apoptotic cells on DOL 1 (1.0%) and a significant decrease by DOL 30 (0.23%) (P = .02). Similarly, expression of the proapoptotic genes BCL2l11 and Pawr were increased at DOL 1, and the antiapoptotic genes Nol3 and Naip2 were significantly increased at DOL 30.

CONCLUSIONS

RVI is a misnomer, but significant changes occur early (by DOL 16) in neonatal mouse hearts. Apoptosis plays a role in RVI, but whether manipulation of apoptotic pathways can prevent or reverse RVI is unknown and warrants further investigation.

In-utero exposure to nicotine alters the development of the rabbit cardiac conduction system and provides a potential mechanism for sudden infant death syndrome

In-utero exposure to tobacco smoke remains the highest risk factor for sudden infant death syndrome (SIDS). To alleviate the risks, nicotine replacement therapies are often prescribed to women who wish to quit smoking during their pregnancy. Cardiac arrhythmias is considered the final outcome leading to sudden death. Our goal in this study was to determine if exposing rabbit fetus to nicotine altered the cardiac conduction system of newborn kittens in a manner susceptible to cause SIDS. Using neuronal markers and a series of immunohistological and electrophysiological techniques we found that nicotine delayed the development of the cardiac pacemaker center (sinoatrial node) and decreased its innervation. At the molecular level, nicotine favored the expression of cardiac sodium channels with biophysical properties that will tend to slow heart rate and diminish electrical conduction. Our results show that alterations of the cardiac sodium current may contribute to the bradycardia, conduction disturbances and other cardiac arrhythmias often associated to SIDS and raise awareness on the use of replacement therapy during pregnancy.

Vaccination and anaphylaxis: a forensic perspective

Aim

To review the available literature pertaining to fatalities following vaccine administration and, in particular, cases of vaccine-related fatal anaphylaxis.

Method

The MEDLINE database was systematically searched up to March 2016 to identify all relevant articles pertaining to fatal cases of anaphylaxis following vaccine administration.

Results

Six papers pertaining to fatal anaphylaxis following vaccination were found relevant. Mast cell tryptase and total IgE concentration was assessed exclusively in one case. Laryngeal edema was not detected in any of these cases, whereas eosinophil or mast cell infiltration was observed in lymphoid organs. In one case, immunohistochemical investigations using anti-tryptase antibodies allowed pulmonary mast cells and degranulating mast cells with tryptase-positive material outside to be identified.

Conclusion

In any suspected IgE-mediated fatal anaphylactic cases, biochemical investigations should be systematically performed for forensic purposes. Splenic tissue should be routinely sampled for immunohistochemical investigations in all suspected anaphylaxis-related deaths and mast cell/eosinophil infiltrations should be systematically sought out in the spleen, myocardium, and coronary artery wall. The hypothesis of fatal anaphylaxis following vaccination should be formulated exclusively when circumstantial data, available medical records, laboratory investigations, and autopsy or histology findings converge in a consistent pattern. The reasonable exclusion of alternative causes of death after all postmortem investigations is also imperative in order to establish or rule out a cause-and-effect relationship between vaccine administration and any presumptive temporarily-related death.

Update on congenital heart disease and sudden infant/perinatal death: from history to future trends

During the 20th century, expert pathologists contributed an in-depth characterisation of the anatomical pathology and associated pathophysiology of congenital heart disease (CHD). Starting in the 1970s, the reported CHD birth prevalence has been increasing, owing to advances in diagnostic methods. Over the years, surgical treatments have been associated with an enormous reduction of CHD mortality. Advances also have been made in understanding the developmental biology and molecular pathogenesis of CHD. In developed countries, sudden infant death syndrome (SIDS) is the most frequent form of death during the first year of life, with a death rate of 0.42 every 1000 births. Unexpected stillbirth has a six- to eightfold greater incidence than that of SIDS and remains unexplained in 40–80% of cases even after autopsy. Specific environmental risk factors, such as maternal smoking, air and water pollution, food contamination, pesticides, etc, can interact with the genetic constitution in complex ways, which may lead to polymorphisms and/or mutations of specific genes, such as polymorphisms in the serotonin transporter gene 5-HTT, the regulator of the synaptic serotonin concentration. Current directions of research in this area are reviewed.

Updates on the Methodological Approaches for Carrying Out an In-Depth Study of the Cardiac Conduction System and the Autonomic Nervous System of Victims of Sudden Unexplained Fetal and Infant Death

This article contains a set of protocols for histopathological techniques that can be used for carrying out in-depth studies of cases of sudden infant death syndrome and sudden intrauterine unexplained fetal death syndrome. In order to enable researchers to advance hypotheses regarding the causes of the unexpected death of infants and fetuses, the authors propose three innovative and accurate methodologies for studying the cardiac conduction system, the peripheral cardiac nervous system, and the central autonomic nervous system. Over the years, these protocols have been developed, modified, and improved on a vast number of cases which has enabled pathologists to carry out the microscopic analyses of the structures which regulate life, in order to highlight all the possible morphological substrates of pathophysiological mechanisms that may underlie these syndromes.

In memory of our research professor Lino Rossi (1923–2004).

Anatomopathological changes of the cardiac conduction system in sudden cardiac death, particularly in infants: advances over the last 25 years

Sudden cardiac death (SCD) is defined as the unexpected death without an obvious noncardiac cause that occurs within 1 h of witnessed symptom onset (established SCD) or within 24 h of unwitnessed symptom onset (probable SCD). In the United States, its incidence is 69/100,000 per year. Dysfunctions of the cardiac conduction and autonomic nervous systems are known to contribute to SCD pathogenesis, even if most clinicians and cardiovascular pathologists lack experience with detailed examination of the cardiac conduction system and fail to recognize lesions that are crucial to explain the SCD itself. In this review, we sought to describe the advances over the last 25 years in the study of the anatomopathological changes of the conducting tissue, in SCD, in mature hearts and particularly in sudden infant death syndrome (SIDS) and sudden intrauterine unexpected death syndrome (SIUDS), through the articles published in our journal Cardiovascular Pathology (CVP). We carried out an extensive Medline search to retrieve and review all articles published in CVP in which the sudden unexpected death of one or more subjects believed healthy was reported, especially if associated with lesions of the conducting tissue in settings that revealed no other explained causes of death, particularly in infants and fetuses. The cardiac conduction findings of resorptive degeneration, His bundle dispersion, Mahaim fibers, cartilaginous meta-hyperplasia, persistent fetal dispersion, left-sided His bundle, septation of the bifurcation, atrioventricular node dispersion, sinus node hypoplasia, Zahn node, His bundle hypoplasia, atrioventricular node, and His bundle dualism were similarly detected in SIDS and SIUDS victims.

Hypoxia at the heart of sudden infant death syndrome?

Sudden infant death syndrome (SIDS) is a significant clinical problem without an accepted pathological mechanism, but with multiple conflicting models. Mutations in a growing number of genes have been found postmortem in SIDS cases, notably genes encoding ion channels. This can only account for a minority of cases, however. Our recent work on a novel mouse model of SIDS suggests a potentially more widespread role for cardiac arrhythmia in SIDS without needing to invoke the inheritance of abnormal ion-channel genes. We propose a model for SIDS pathogenesis whereby postnatal hypoxia leads to delayed maturation of the cardiac conduction system and an increased risk of cardiac arrhythmia. Our model may integrate several epidemiological findings related to risks factors for SIDS, and agrees with previous work suggesting a common final pathological pathway in SIDS.

Primary Cardiac Fibroma and Cardiac Conduction System Alterations in a Case of Sudden Death of a 4-month-old Infant

A 4-month-old female infant considered to be in good health died suddenly and unexpectedly. Post- mortem examination was requested, with clinical diagnosis of sudden infant death syndrome. At autopsy the infant was described in good health. Histo- logical examination of the heart found a cardiac fibroma compressing the atrio-ventricular node and the examination of the cardiac conduction system showed an accessory fiber of Mahaim (nodo-ventricular) and cartilaginous metaplasia of the cardiac fibrous body. Probably the concomitant presence of cardiac conduction system abnormalities and a septal fibroma, compressing the atrio-ventricular node, could have an important role in causing the sudden death.

Ontogenesis of human cerebellar cortex and biopathological characterization in sudden unexplained fetal and infant death

The aims of this study were to investigate in the human cerebellar cortex the structural and biological ontogenetic features, the possible presence of alterations in cases of sudden unexplained fetal and infant death, and the involvement of the maternal cigarette smoking in developmental abnormalities. We analyzed 52 brains of fetal and infant death victims, aged from the second gestational trimester to 12th postnatal month. In the cerebellar cortex we evaluated, besides the morphological aspects, the expression of several biomarkers implicated in proliferative processes (c-fos, proliferating cell nuclear antigen, and apoptosis) as well as the presence of the neurotransmitter somatostatin, which is strongly implicated in central nervous system differentiation, and of EN2 gene. The observed features of the cerebellar cortex, mainly confined to the transient external granular layer, were high proliferative activity and high expression of both somatostatin and EN2 gene in prenatal life and high apoptotic index after birth. In 41% of the sudden unexplained death victims, in the greater part with smoking mothers, we observed different biopathological alterations of the cerebellar cortex. Maternal smoking is increasingly being demonstrated to be one of the main contributors to developmental neurological alterations in the offspring.

Maternal smoking and sudden infant death syndrome: epidemiological study related to pathology

Various risk factors have been postulated to be related to sudden infant death syndrome (SIDS). Despite its reduction, thanks to the "Back to Sleep" campaign, SIDS is still a major cause of infant mortality in the first year of life. The purpose of this study was to correlate the different risk factors with the autopsy results and thus to determine if one or more of these variables is really specific for SIDS. We collected 128 sudden infant death victims with clinical diagnosis of SIDS and performed a complete autopsy with in-depth histology on serial sections, particularly of the brainstem, in accordance with our necropsy protocol. Histopathologic and immunohistochemical examination of the central autonomic nervous system revealed, in 78 cases of the SIDS group, the following anomalies: hypodevelopment of the arcuate nucleus, somatostatin positive hypoglossus nucleus, tyrosine hydroxylase negativity in the locus coeruleus, gliosis, and hypoplasia of the hypoglossus nucleus. A significant relation was found between maternal smoke and brainstem alterations.

Hypoplasia and neuronal immaturity of the hypoglossal nucleus in sudden infant death

OBJECTIVE

To report the case of five month old female baby with a history of episodes of gastro-oesophageal reflux and pneumonia. Her sudden death offered a unique insight into the possible role of delayed neuronal maturation and hypoplasia of the hypoglossal nucleus in representing a likely morphological substrate of sudden death.

METHODS

Morphometric analysis was carried out with an Image-Pro Plus Image analyser (Media Cybernetics) on both sides of the brain stem.

RESULTS

Hypoplasia and neuronal immaturity of the hypoglossal nucleus were demonstrated, accompanied by hypoplasia of the arcuate nucleus.

CONCLUSIONS

Much attention should be paid to the possible role of the hypoglossal nucleus in determining a lethal outcome in infancy through impairment of deglutition and subsequent recurrent episodes of pneumonia, and as a necropsy finding.

Sudden infant death syndrome (SIDS) shortly after hexavalent vaccination: another pathology in suspected SIDS?

Experts from panels of the European Agency for the Evaluation of Medical Products have investigated whether there might be a link between hexavalent vaccines and some cases of deaths that occurred. Participants included pathologists with experience in the field of vaccines and sudden infant death syndrome who conducted autopsies. However, to the best of our knowledge, little, if any, attention was paid to examination of the brainstem and the cardiac conduction systems on serial sections, nor was the possibility of a triggering role of the vaccine in these deaths considered. Herein we report the case of a 3-month-old female infant dying suddenly and unexpectedly shortly after being given a hexavalent vaccination. Examination of the brainstem on serial sections revealed bilateral hypoplasia of the arcuate nucleus. The cardiac conduction system presented persistent fetal dispersion and resorptive degeneration. This case offers a unique insight into the possible role of hexavalent vaccine in triggering a lethal outcome in a vulnerable baby. Any case of sudden unexpected death occurring perinatally and in infancy, especially soon after a vaccination, should always undergo a full necropsy study according to our guidelines.

Top of the charts: download versus citations in the International Journal of Cardiology

The medical literature is growing at an alarming rate. Research assessment exercises, research quality frameworks, league tables and the like have attempted to quantify the volume, quality and impact of research. Yet the established measures (such as citation rates) are being challenged by the sheer number of journals, variability in the "gold standard" of peer-review and the emergence of open-source or web-based journals. In the last few years, we have seen a growth in downloads to individual journal articles that now easily exceeds formal journal subscriptions. We have recorded the 10 top cited articles over a 12-month period and compared them to the 10 most popular articles being downloaded over the same time period. The citation-based listing included basic and applied, observational and interventional original research reports. For downloaded articles, which have shown a dramatic increase for the International Journal of Cardiology from 48,000 in 2002 to 120,000 in 2003 to 200,000 in 2004, the most popular articles over the same period are very different and are dominated by up-to-date reviews of either cutting-edge topics (such as the potential of stem cells) or of the management of rare or unusual conditions. There is no overlap between the two lists despite covering exactly the same 12-month period and using measures of peer esteem. Perhaps the time has come to look at the usage of articles rather than, or in addition to, their referencing.

Sudden infant death syndrome "gray zone" disclosed only by a study of the brain stem on serial sections

Sudden infant death syndrome (SIDS) "gray zone" or borderline cases are defined as those cases in which it is difficult to establish whether the pathological findings are sufficiently severe to have caused the death. Examination of the brainstem in 103 cases of SIDS disclosed five SIDS "gray zone" cases in which only further investigations of serial sections successfully identified anatomico-pathological findings that likely represent the morphological substrates for a sudden reflexogenic death. A complete autopsy was performed, including close examination of the brainstem and cardiac conduction system, according to our guidelines. Our five cases are consistent with the triple-risk model of SIDS, a hypothesis postulating an underlying biological vulnerability to exogenous stressors or triggering factors in a critical developmental period. Inflammatory infiltrates (cases 1 and 2), necrotic focus of the solitary tract (case 3), hemangioendothelioma (case 4) and mild pneumonia (case 5) alone might or might not have accounted for the sudden deaths, if it had not been for the location and/or concomitant presence of brainstem abnormalities that could have had a triggering role in causing the sudden death of these babies.

Sudden infant death triggered by dive reflex

The dive reflex is the reflex mechanism most frequently considered in the aetiopathogenesis of sudden infant death syndrome (SIDS). This seems to persist in human beings as an inheritance from diver birds and amphibians. It has been reported that washing the face with cold water or plunging into cold water can provoke cardiac deceleration through the intervention of the ambiguus and the vagal dorsal nuclei. This report describes a case of SIDS that offers a unique insight into the role of the dive reflex in determining a lethal outcome. Examination of the brainstem on serial sections revealed severe bilateral hypoplasia of the arcuate nucleus and gliosis of the other cardiorespiratory medullary nuclei. The coronary and cardiac conduction arteries presented early atherosclerotic lesions. The possible role of parental cigarette smoking in the pathogenesis of arcuate nucleus hypoplasia and early coronary atherosclerotic lesions is also discussed.

Early atherosclerotic lesions of the cardiac conduction system arteries in infants

INTRODUCTION

Although several studies have described initial atherosclerotic lesions of the coronary arteries, already detectable in infancy and even during the intrauterine life, little, if any, attention has been given to the possible involvement of the cardiac conduction system arteries. In particular, to the best of our knowledge, none has considered the lesions of the cardiac conduction arteries as an initial stage of atherosclerosis.

METHODS

The cardiac conduction system of 70 infants dying suddenly and unexpectedly was removed in two blocks for paraffin embedding and serially cut.

RESULTS

The histological study of the cardiac conduction arteries of the 70 cases examined showed a normal structure in 55 cases (78.57%). In 15 cases (21.43%), there was a thickening of the sinoatrial node and/or atrioventricular artery associated with a thickening of varying severity in coronary artery walls. The lesions were marked by thickening and deposits of amorphous material and mainly lipids in the intima, as well as fragmentation of the elastic fiber system. A significant correlation was evident between early atherosclerotic lesions and both formula feeding and parental cigarette smoking (P<.05, chi(2) test).

CONCLUSIONS

The combination of both the considered risk factors seems to increase the early atherogenic effect of each noxa because the coronary lesions were more diffused in formula-fed infants whose parents both smoked.

Study of the brainstem, particularly the arcuate nucleus, in sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death (SIUD)

Complete examination of the brainstem involves transverse serial 5-microm sections made throughout the entire brainstem. The number of serial sections varies from 360 in sudden intrauterine unexplained death (SIUD) to 600 in term fetuses to over 1400 sections in sudden infant death syndrome (SIDS) victims. The procedure is not applicable in all histopathological laboratories, owing to the need for additional technical personnel. The simplified procedure allows a remarkable reduction of the number of sections. The brainstem is divided into 3 blocks. The first, cranial block, extends from the border between the medulla oblongata and pons up to the upper pole of the olivary nucleus. The second, intermediate block, corresponding to the submedian area of the inferior olivary nucleus, has as reference point the obex and extends 2 to 3 mm above and below the obex itself. The third, caudal block, includes the lower pole of the inferior olivary nucleus and the lower adjacent area of the medulla oblongata. Examinations of the brainstems from 106 SIDS victims, 30 controls, and 51 stillborns underlined a remarkable variability, particularly of the arcuate nucleus. The simplified examination of the brainstem makes it possible to evaluate the structures, examining 3 specific levels, defined by morphologic reference points.