Myocardial infarcts in infants and children. I. A necropsy study in congenital heart disease

Polyploid cardiomyocytes: implications for heart regeneration

Terminally differentiated cells are generally thought to have arrived at their final form and function. Many terminally differentiated cell types are polyploid, i.e. they have multiple copies of the normally diploid genome. Mammalian heart muscle cells, termed cardiomyocytes, are one such example of polyploid cells. Terminally differentiated cardiomyocytes are bi- or multi-nucleated, or have polyploid nuclei. Recent mechanistic studies of polyploid cardiomyocytes indicate that they can limit cellular proliferation and, hence, heart regeneration. In this short Spotlight, we present the mechanisms generating bi- and multi-nucleated cardiomyocytes, and the mechanisms generating polyploid nuclei. Our aim is to develop hypotheses about how these mechanisms might relate to cardiomyocyte proliferation and cardiac regeneration. We also discuss how these new findings could be applied to advance cardiac regeneration research, and how they relate to studies of other polyploid cells, such as cancer cells.

Acute myocardial infarction in a premature infant on the first day of life

Neonatal myocardial infarction (MI) is a very rare but potentially life-threatening condition with an approximated mortality rate of 80%. Congenital heart disease, anomalous coronary artery anatomy, thromboembolism, coagulopathy, birth asphyxia or myocarditis have been suggested as possible causes of MI. Here we report the case of a premature infant who died at about 40 h of life from a massive MI. Autopsy revealed an occlusive thrombus in the right coronary artery. An isolated prothrombotic status, characterized by a double copy variant of the MTHFR A1298C mutation, was identified at the postmortem genetic studies as a possible explanation for the coronary artery thrombosis. No other risk factors were detected.

Successful treatment of a newborn with acute myocardial infarction on the first day of life

Cardiogenic shock occurring after acute neonatal myocardial infarction (MI) due to coronary artery thrombosis is very rarely encountered. Acute neonatal MI typically presents suddenly with usually a fatal outcome. Treatment options in patients with this condition are limited. There are previous case reports in the literature advocating the use of extracorporeal membrane oxygenation for hemodynamic support. In this report, we present a newborn with severe MI secondary to thrombus formation within the left anterior descending coronary artery. There also proved to be a Factor V Leiden heterozygotic mutation. The patient initially presented with cardiogenic shock. After resuscitation and thrombolytic therapy were administered, coronary artery patency was restored resulting in myocardial revitalization and recovery of left-ventricular function within 4 weeks.

Fatal infant myocardial infarction caused by ball-IN-valve mechanism from a dysplastic aortic valve

BACKGROUND

Acute myocardial infarction (AMI) can occur in infants. Early identification of AMI can allow for specific therapies aimed at improving patient outcomes.

OBJECTIVE

This article describes a case of an infant with AMI caused by a previously unreported mechanism and reviews diagnostic and therapeutic strategies for dealing with this rare disease.

CASE REPORT

We present a case of a 5-week-old infant with a fatal AMI due to a pedunculated nodule from a dysplastic aortic valve leaflet creating a ball-in-valve mechanism and occluding the left main coronary artery.

CONCLUSION

AMI is an important diagnostic consideration in any infant presenting with signs of unexplained cardiogenic shock. Practitioners who care for children should be aware of diagnostic and therapeutic strategies for AMI in infants.

Myocardial necrosis and infarction in newborns and infants

PURPOSE

This study aimed to investigate the incidence, and underlying associations, of myocardial necrosis occurring in infants undergoing autopsy.

METHODS

An autopsy database containing anonymized details of all infant autopsies conducted at Great Ormond Street Hospital between January 1996 and December 2010 was searched to identify all infants with myocardial necrosis. The characteristics of the necrosis and any underlying associations were reviewed.

RESULTS

Myocardial necrosis was recorded in 187 autopsies out of a total of 1,637 (11.4%), and was localized to the papillary muscles, subendocardial region, or trabeculae in 50.8% of cases. The most common associations were congenital heart disease, perinatal asphyxia, coronary artery abnormalities, or sepsis. Three cases of apparently idiopathic myocardial infarction were identified and are described in detail.

CONCLUSIONS

Myocardial necrosis is relatively common in infants who die and undergo autopsy, and is most commonly associated with congenital heart disease and perinatal asphyxia. Myocardial infarction can occur in infancy in the absence of any apparent underlying cause: the etiology of these cases is unclear.

Neonatal myocardial infarction: case report and review of the literature

Myocardial infarction in a neonate is rare. We describe the case of a full-term male who presented with respiratory distress. A chest radiograph demonstrated cardiomegaly. An electrocardiogram revealed ST segment changes suggestive of ischemia. Cardiac enzymes were elevated and an echocardiogram revealed a regional wall motion abnormality. Cardiac catheterization was performed demonstrating occlusion of the ramus intermedius branch of the left main coronary artery. The patient decompensated, requiring extracorporeal membrane oxygenation (ECMO). The infant was able to be decannulated from ECMO support in 5 days and was ultimately discharged on hospital day 25. We review this case as well as the literature on neonatal myocardial infarction.

A case of an infant with flail tricuspid valve due to spontaneous papillary muscle rupture: was neonatal lupus the culprit?

A 3-month-old infant presented in extremis with a flail tricuspid valve. The authors theorized that the genesis of her papillary muscle rupture was perinatal ischemia compounded by worsening pulmonary valvular stenosis leading to excessive fiber tension. Her underlying diagnosis of autoimmune-mediated heart block with endocardial fibroelastosis and prenatal glucocorticoid steroid treatment represents potentiating factors.

Pulmonary Stenosis

Balloon valvuloplasty provides optimal treatment for moderate and severe pulmonary valve stenosis. Dysplastic pulmonary valves may not respond to balloon dilation and frequently require surgical treatment. Balloon angioplasty with or without stenting is the preferred treatment of peripheral pulmonary stenosis.

A strange complex of diffuse congenital cardiovascular disease and cardiomyopathy, with localised myocardial calcification

This unique case is of a man, followed clinically since infancy, who had a ventricular septal defect which closed spontaneously, a small arterial duct, and a minor degree of aortic coarctation, all without obvious symptoms. He later developed progressive cardiac failure which was attributed to some obscure form of congenital cardiomyopathy. He died at the age of 45 years. Necropsy showed a grossly abnormal arrangement of ventricular myocardial fascicles and bands, with absence of the papillary muscles causing tricuspid and mitral regurgitation. The various malformations are considered to be a gross example of a diffuse congenital cardiovascular disease complex, to the best of our knowledge previously undescribed.

Right ventricular function in congenital heart disease: pressure and volume overload lesions

The right ventricle is often subject to both pressure and volume overload in congenital heart disease. Evaluating right ventricular function in both the native lesion and after surgery in light of these loading conditions, presents a unique challenge for investigators studying these misshapen hearts. The purpose of this article is to briefly delineate what is generally known about right ventricular function in congenital heart disease and to touch on some noninvasive imaging modalities which have helped shed some light on this matter.

Right ventricular pathology in chronic pulmonary hypertension

Right ventricular free wall biopsy specimens in 40 patients undergoing surgery for relief of chronic thromboembolic pulmonary hypertension were normal in 5%, disclosed only myocyte hypertrophy in 80%, mild focal fibrosis in 12.5%, and myocarditis in 2.5%. There was no relation between postsurgical functional or hemodynamic outcomes and the presence of focal fibrosis.

Right ventricular regional wall motion abnormality in congenital heart disease

Four cases of congenital heart disease with right ventricular overload and echocardiographic evidence of persistent right ventricular regional wall motion abnormalities are presented. Right ventricular infarction could be a possibility. Such regional wall motion abnormalities could add to overall right ventricular dysfunction in these cases. Echocardiography is useful in diagnosis. Right ventricular wall motion abnormalities should be studied in detail in all cases of congenital heart disease with right ventricular overload.

Isolated right ventricular infarction in a case of hypertrophic cardiomyopathy

A case of isolated right ventricular infarction in a young female with hypertrophic cardiomyopathy is reported. This case highlights the importance of detailed evaluation of right ventricle in cases with hypertrophic cardiomyopathy.

Postinfarction ventricular arrhythmias in children

Because limited information is available on significant arrhythmias after myocardial infarction in pediatric patients, this study was performed to determine the incidence and impact of ventricular tachycardia or fibrillation on the postinfarction course in patients aged 1 day to 16 years. Review of 96 such children showed a wide range of underlying heart disease (56 patients with congenital heart disease, 12 with cardiomyopathy, and 28 with acquired heart disease). Postinfarction ventricular tachycardia/fibrillation occurred commonly (28% of patients with acute myocardial infarction) and early (84% by 2 days after diagnosis). Postinfarction mortality was high in patients with acute myocardial infarction (61%) and appeared to be independent of type of associated heart disease. Ventricular tachycardia/fibrillation was associated with higher mortality rates (approximately 80%) in patients with acute or remote myocardial infarction. The 61 postinfarction survivors were monitored for an average of 4.9 years, and none had significant recurrent ventricular arrhythmias or late sudden death.

The effects of cyanosis on myocardial blood flow, oxygen utilization, and lactate production in dogs

To elucidate differences in myocardial blood flow and metabolism between cyanotic and normal hearts, a model of chronic cyanosis was created in five adult mongrel dogs by anastomosing the inferior vena cava to the left atrium. After 6 to 9 months, myocardial blood flow, the ratio of subendocardial to subepicardial flow, oxygen consumption, oxygen extraction ratio, and lactate consumption in these cyanotic dogs and five control dogs were determined under baseline conditions and during pharmacologic stress with isoproterenol (0.2 micrograms/kg/min). Radioactive microspheres were used to determine left and right ventricular blood flow rates, and arterial and coronary sinus differences in oxygen and lactate levels were measured. At baseline and during stress, oxygen consumption and oxygen extraction ratios were identical in control and cyanotic hearts. Total myocardial blood flow was increased with stress and did not differ between cyanotic and control hearts. Left ventricular muscle from cyanotic hearts did exhibit lower endocardial/epicardial blood flow ratios than those of control hearts at rest, and the relative subendocardial flow decreased further with stress. During isoproterenol infusion, myocardial lactate production, indicative of anaerobic metabolism, was evident in two of five cyanotic animals and none of the control dogs. The relative subendocardial ischemia and its further aggravation by stress in cyanotic hearts may contribute to the pathophysiologic basis of myocardial dysfunction in cyanotic heart disease.

Cardiac histologic pathology characteristic of trisomies 13 and 21

To identify fetal histologic features characteristic of specific chromosomal anomalies, we reviewed histologic slides of 415 cases, including therapeutic and spontaneous abortuses, stillbirths, and perinatal deaths. These included 126 cases (30%) with karyotypically confirmed trisomy 21 and 23 cases (5.5%) with trisomy 13. Two histologic abnormalities of the fetal heart were identified that correlated with specific karyotypic abnormalities: (1) a discrete central papillary muscle calcification was present in 14 of 85 (16%) cases with trisomy 21, in seven of 18 (39%) cases with trisomy 13, and in six of 255 (2%) controls (P less than .001); and (2) a focal ventricular epicardial lymphocytic infiltrate was present in 22 of 93 (24%) cases with trisomy 21 versus nine of 284 (3%) controls (P less than .001). When both histologic abnormalities coexisted, trisomy 21 was present in five of six cases (83%). Neither histologic finding was significantly associated with fetal or maternal infection or congenital heart defects. In a restricted prospective study of the hearts of fetuses with trisomy 21, papillary muscle calcification was demonstrated by specimen radiographs in four of six (67%) cases; one case was studied by specimen ultrasonogram, which identified a papillary muscle echodensity. We conclude that (1) a focal ventricular epicardial lymphocytic infiltrate is characteristic of trisomy 21, (2) papillary muscle microcalcifications are characteristic of trisomies 13 and 21, and (3) further studies are needed to determine whether papillary muscle calcification might be useful in antenatal ultrasonographic screening for chromosomal anomalies.

Coronary artery abnormalities and right ventricular histology in hypoplastic left heart syndrome

OBJECTIVES

To determine whether right ventricular preservation is compromised in any anatomic subgroup of hypoplastic left heart syndrome, we assessed the coronary artery anatomy and myocardial histologic features of 151 postmortem specimens with hypoplastic left heart syndrome.

BACKGROUND

Although previous studies have shown that coronary artery abnormalities are more prominent in the subgroup of patients who have a patent mitral valve and obstructed aortic valve, it has not been established that these abnormalities compromise right ventricular perfusion.

METHODS

Eighty-nine specimens with a patent mitral valve and aortic atresia, 52 with mitral and aortic atresia and 10 with patent mitral and aortic valves were examined. Histologic sections of the right ventricle, left ventricle and coronary arteries were obtained from 64 study hearts and 5 control hearts.

RESULTS

Gross coronary anomalies included coronary-cameral communications (n = 29), single left coronary artery (n = 2), single right coronary artery (n = 1) and tortuosity (n = 19). Coronary-cameral communications and tortuosity were significantly associated with the subgroup that had mitral hypoplasia and aortic atresia. Coronary artery wall thickness relative to lumen diameter was not different among the subgroups. No areas of coronary artery stenosis or interruption were discovered. Although endocardial fibroelastosis of the left ventricle was strongly associated with the mitral hypoplasia and aortic atresia group, the right ventricular histologic findings were similar in all subgroups and were not differentially affected by older age.

CONCLUSIONS

Although the incidence of coronary abnormalities is greater in patients with mitral hypoplasia and aortic atresia, in this study there was no apparent difference in perfusion of the right ventricle among the anatomic subgroups of hearts with hypoplastic left heart syndrome.

Electrocardiographic criteria for diagnosis of acute myocardial infarction in childhood

Myocardial infarction (MI), a common occurrence in adults, is generally considered to be rare in children. Electrocardiographic criteria for diagnosis of MI in adults are well known and accepted, but no general criteria exist for children. We report 37 autopsy-proved cases of transmural MI and electrocardiographic evidence of MI in 30 of these cases. A variety of conditions previously reported to produce "pseudo-infarction" are included in these cases of MI, including myocarditis, hypertrophic cardiomyopathy, and the cardiomyopathy of Duchenne's muscular dystrophy. Compilation of the electrocardiographic data in all patients allowed for the development of criteria for this diagnosis of MI in childhood, and include wide Q waves (greater than 35 ms) with or without Q-wave notching, ST-segment elevation (greater than 2 mm), and prolonged QT interval corrected for heart rate (QTc greater than 440 ms) with accompanying Q-wave abnormalities. With use of these electrocardiographic criteria, an additional 3 patients were subsequently diagnosed prospectively with MI and confirmed on autopsy. Pathologic evaluation confirmed the location of infarction predicted by the electrocardiograms in all 3 cases.

Anesthesia for Cardiac Surgery in Newborns with Congenital Heart Disease

The repair of complex congenital heart disease in the neonatal period is an evolving practice that began a decade ago and has resulted in improved survival and reduced long term morbidity. Surgical techniques and anesthetic, management hare evolved to care for these uniquely challenging infants. Optimal anesthetic care requires a sound basis in normal and pathologic neonatal and dedopmental physiology, cardiac and pediatric anesthesia, and cardiopulmonary bypass management. Typical concerns in neonatal congenital heart patients include a reduced myocardial compliance and poorly

developed calcium transport systems. This limits stroke volume and increases calcium requirements in the post-bypass patient. Additionally, abnormal blood flow patterns are common and may be adversely affected by inotropes, inspired oxygen concentration, carbon dioxide tension, and mechanical ventilation. The impact of cardiopulmonary bypass on the neonate is extreme. Infants are commonly cooled to 15°C, their blood volume is hemodiluted by 3-4 fold, and periods of total circulatory arrest for up to 60 min are routine. The physiologic impact of these biologic extremes on organ function must be anticipated. Bypass management must assure optimal distribution of pump flow to minimize any impediment to organ protection. High dose narcotics combined with a benzodiazepine have become an integral part of anesthetic management for the neonate with congenital heart disease. Combined intravenous drug therapy provides a complete anesthetic (sedation amnesia and analgesia), hemodgnamic stability, reduced stress hormone release, and control of pulmonary vascular reactivity. Thii reduces the need for multiple inotropic therapy aimed at decreasing pulmonary vascular resistance and improving myocardial contractility. This manuscript provides an in-depth understanding of the anesthetic management of the neonate with complex congenital heart disease. The overall goal of anesthetic management is to deliver a patient to the ICU with stable hemodynamics and a clear management plan based on intraoperative observations and interventions.

Postmortem audit in a paediatric cardiology unit

Postmortem examinations performed on 76 children with a clinical diagnosis of congenital heart disease were reviewed retrospectively and compared with the findings before death. Both operated and unoperated cases were studied over a three year period. Despite intensive investigation during life, there was a high rate of unsuspected abnormalities at necropsy (80%): 29 cases had undiagnosed additional cardiac anomalies or surgical flaws, which contributed to death in 13 cases. Defects in surgery were uncommon but permitted modification in surgical technique to avoid recurrence. Myocardial necrosis and pulmonary foreign body embolism were common findings, the importance of which is uncertain and requires further study for their prevention. Even in the most thoroughly investigated cases postmortem examination has a high yield of clinically important pathology which is undetected during life.

Transmural myocardial perfusion

The predilection for subendocardial underperfusion and ischemia is great and must be considered in the management of any patient, especially if there is coronary artery disease or ventricular hypertrophy. Although the mechanisms of subendocardial ischemia remain to be fully defined, they are clearly associated with the transmural distribution of intramyocardial systolic pressures. Even though almost all the myocardium is perfused in diastole, a reduction of diastolic perfusion pressure or duration will result in subendocardial ischemia. The factors that produce subendocardial ischemia are all associated with a reduction or loss of coronary flow reserve, and as our ability to measure flow reserve in humans improves, it is likely that we will be able to select medical or surgical therapy that will minimize or abolish subendocardial ischemia. For example, it will someday become possible to choose a time for valve replacement in an asymptomatic patient to obtain maximal protection of the myocardium or to select the right combination of therapies for the immediate post-operative period so that as much myocardium as possible will be spared. The more we learn to understand the mechanisms of subendocardial ischemia, the sooner will we be able to achieve these desired ends.

Optimal examination of the normally formed perinatal heart

Because infants rarely suffer coronary artery thrombosis, it is mistakenly assumed that they seldom have significant ischemic myocardial injury. However, ischemic myocardial necrosis (INM) is common in the papillary muscles and subendocardium of stressed newborns and other infants. Standard dissection methods encourage only routine examination and limited sampling of the small perinatal heart, and most myocardial injury is never discovered. After evaluating published methods, a simple technique was developed to open and prepare the normally formed infant heart for optimal macroscopic and microscopic evaluation. Symmetrical anterior incisions of the atria and ventricles allow the atria, ventricles, and outflow tracts to be viewed almost simultaneously. A single change allows the heart to be "unrolled" into a plane for roentgenographic study of injected coronary arteries. The method for sampling the myocardium and the conduction system allows identification of more than 90 per cent of the IMN sites without adding significant costs. The recognition of significant IMN plays a valuable role in evaluating and explaining certain infant deaths.

Myocardial ischemia in patients with pulmonary atresia and intact ventricular septum

Children who die after operation for pulmonary atresia and intact ventricular septum may have myocardial ischemia. The relation between histologic evidence of myocardial ischemic injury and the presence of a right ventricle to coronary artery fistula, coronary artery dysplasia and operation in 17 autopsy specimens was assessed. Age at death ranged from 1 day to 16 years (median, 11 days). Of the 17 hearts, 6 (35%) had right ventricle to coronary artery fistulas, 5 of which had coronary artery dysplasia. In three cases, there was segmental or complete absence of a coronary artery. Ischemia was present in four of these six hearts, two of which had right ventricular outflow reconstruction. Six of the 11 hearts without right ventricle to coronary artery fistulas also had myocardial ischemia. Of these six cases, four had right ventricular outflow reconstruction and two had shunt operations. Death occurred from 1 to 8 days (mean 3) after operation. Hearts with pulmonary atresia and intact ventricular septum may have myocardial ischemia with or without either right ventricle to coronary artery fistulas or coronary artery dysplasia. Myocardial ischemia may occur after right ventricular outflow reconstruction or shunt operations. Thus, myocardial ischemia occurs commonly in patients with pulmonary atresia and intact ventricular septum and is not always related to coronary abnormalities or operation.

Recurrent myocardial infarction and unexpected sudden death in a case of d-loop d-transposition of the great arteries associated with single coronary artery

A 40-year-old man with d-loop d-transposition of the great arteries associated with single coronary artery type 3 by Hvass died unexpectedly. Postmortem study demonstrated myocardial infarction in the posterior portion of the right ventricle and interventricular septum, and complete obstruction of the proximal right coronary artery. The etiology of the unexpected death is discussed.

Right ventricular subendocardial infarction in a patient with pulmonary hypertension, right ventricular hypertrophy, and normal coronary arteries

Right ventricular infarction is usually associated with coronary artery disease and concomitant left ventricular infarction. Isolated right ventricular subendocardial necrosis was discovered at autopsy in a 52-year-old woman with pulmonary hypertension, right ventricular hypertrophy, and normal coronary arteries, who died with septicemia 41 days after mitral valve replacement. This represents the first well-documented report of isolated right ventricular subendocardial infarction associated with normal coronary arteries.

Natural history of left ventricular function in neonatal Coxsackie myocarditis

Three neonates are described who had severe congestive cardiac failure following Coxsackie-B virus infection. Overall left ventricular function was depressed and accompanied by regional differences in wall motion. Recovery has been gradual, and after 40 or more months of follow-up, all three infants still have evidence of myocardial damage. This provides further evidence linking myocarditis with dilated cardiomyopathy.

Left ventricular function in persistent pulmonary hypertension of the newborn. Computer analysis of the echocardiogram

Regional and global left ventricular function was assessed in 23 neonates with persistent pulmonary hypertension using computer assisted analysis of their left ventricular echocardiograms and compared with that in 50 healthy neonates. End diastolic left ventricular dimension was normal and end systolic dimension increased while percentage left ventricular shortening and peak velocity of circumferential fibre shortening decreased indicating impaired systolic performance. The peak rate of increase in left ventricular diameter in early diastole was significantly decreased and the durations of the rapid filling and isovolumic relaxation periods were prolonged suggesting resistance to left ventricular filling due to changes in diastolic myocardial properties. This abnormal left ventricular cavity function may have been due to a combination of increased diastolic wall thickness, reduced percentage systolic wall thickening, increased relative wall thickness, and pronounced reduction in peak rates of systolic wall thickening and diastolic wall thinning Seven neonates with persistent pulmonary hypertension died, and of the three examined at necropsy all had left ventricular hypertrophy and two extensive subendocardial haemorrhage and infarction affecting the right and left ventricular papillary muscles. Thus left ventricular dysfunction appears to be a common feature in neonates with this disorder and may be readily detected using computer analysis of left ventricular echocardiograms. Unfortunately, no single echo measurement was useful prognostically. Left ventricular dysfunction in persistent pulmonary hypertension probably results from a combination of hypoxaemia, acidaemia, and pulmonary hypertension, and although it may contribute to the high mortality in this syndrome, a correlation between the severity of left ventricular dysfunction and clinical outcome could not be shown.

Cerebral arteriovenous malformation in neonates. The role of myocardial ischemia

Ischemic myocardial damage was identified as a complicating feature in the clinical course of 12 newborn infants who died in congestive failure with cerebral arteriovenous malformation. Electrocardiograms of 11 patients showed signs of chamber hypertrophy and T wave and ST segment features of varying degree compatible with ischemia or infarction. Histological evidence of myocardial necrosis or infarction was detected in seven of the ten infants from whom autopsy material was still available.

Ischemic papillary muscle necrosis in stressed newborn infants

The recent association of transient tricuspid insufficiency in newborn infants with ischemic papillary muscle necrosis prompted a detailed retrospective clinical and histologic analysis of autopsied infants who died within seven days of birth between 1973 and 1977. Infants with congenital heart disease, erythroblastosis fetalis, and known congenital viral infections were excluded. Thirty-one of 82 infants had at least one site of ischemic myocardial necrosis: 11 had lesions only in the right ventricle, 13 had lesions only in the left ventricle, and seven had bilateral lesions. The apical region of an anterior papillary muscle was the most common site. IMN occurred more commonly in older, larger infants. Asphyxia at birth, a murmur of atrioventricular valve insufficiency, and signs of congestive heart failure correlated well with the presence of IMN, but few other perinatal events predicted its occurrence. This report suggests that IMN is a common event in stressed infants who die early in life and probably is related to episodic hypoperfusion of the myocardium.

Papillary muscle necrosis in a neonatal autopsy population: incidence and associated clinical manifestations

Papillary muscle necrosis was found in 24 of 84 neonates without congenital heart disease who died and were autopsied during a 17-month study period. The lesion was most prevalent in infants greater than or equal to 3,000 gm birth weight (59%), but papillary muscle necrosis was also noted in 25% of the infants of medium birth weight (1,500 to 2,999 gm) and in 19% of the very low-birth-weight infants (less than 1,500 gm). Papillary muscle necrosis in the highest birth-weight group correlated with five-minute Apgar scores of 6 or less, meconium aspiration syndrome, seizures, congestive heart failure, increased cardiothoracic ratio (greater than or equal to 0.60), and ischemic changes on electrocardiogram. In the medium- and very low-birth-weight groups, however, patients with papillary muscle necrosis could seldom be differentiated clinically from their birth-weight peers without the lesion, even in retrospect.

Coronary arterial lesions and myocardial necrosis in stillbirths and infants

In a detailed study of the coronary arterial tree and myocardium in 256 stillbirths and infants, abnormalities of the coronary arterial tree were noticed in 79 infants, and necrotic lesions of the myocardium in 111 infants. Of the 79 infants with arterial lesions, 70 had associated myocardial necrosis or scarring, or both; the group with coronary arterial lesions, therefore, accounted for the majority of cases with myocardial damage. The myocardial lesions varied from small zones of subendocardial damage, to larger 'geographical' zones of necrosis scattered haphazardly through the myocardium, and a small group where massive necrotic lesions of the papillary muscles were present. While the coronary arterial lesions were associated with all three patterns, they were particularly found in association with the 'geographical' and papillary muscle changes. The coronary arterial lesions varied from zones of acute focal, medial necrosis to severe proliferative intimal lesions and medial defects, with a distinct progression of changes from the acute to the more established lesions. The coronary arterial lesions were seen most commonly in association with conditions that could produce severe hypoxia, and it is argued that they result from hypoxia. It is suggested further that the myocardial damage, so commonly associated with the coronary arterial lesions, could compromise the ability of the hypoxic infant to respond to such an insult. The coronary arterial lesions seen in this group of young infants could offer one explanation for the later development of a variety of other pathological conditions seen in adolescents and young adults.

Infantile cardiomyopathy with histiocytoid change in cardiac muscle cells. Report of six patients

Clinical and pathologic findings are presented in 14 patients (six newly reported, eight described previously), all children ranging in age from 6 to 24 months, with a clinicopathologic syndrome termed "infantile cardiomyopathy with histiocytoid change in cardiac muscle cells." This syndrome is manifested clinically by severe, eventually fatal cardiac arrhythmias, and is characterized pathologically by cardiac hypertrophy and by a distinctive type of focal degeneration of the muscle cells, which lose their myofibrils, undergo marked mitochondrial hyperplasia, become rounded in shape and enlarged, and resemble histiocytes. Evidence is presented to support the conclusions that these manifestations are those of a cardiomyopathy, that cardiac hypertrophy precedes the onset of the clinical features, that the focal degeneration is likely to be a cause rather than a consequence of the arrhythmias, and that the latter develop only in the late stages of the disorder. The etiology of this cardiomyopathy remains unclear.

Myocardial infarction in the newborn: a case report complicated by cardiogenic shock and associated with normal coronary arteries

Fatal myocardial infarction occurring in a neonate is reported. The patient presented with a clinical picture of cardiogenic shock simulating a hypoplastic left heart syndrome. Etiology of the myocardial infarction is uncertain for the coronary arteries were patent, anatomically and histologically normal, and there was no significant associated cardiac defect. The possible etiologies in relationship to myocardial infarction in the neonatal period are presented.