Sudden cardiac death: definition, mechanisms and risk factors

Sudden cardiac death is defined as natural death due to cardiac causes, heralded by abrupt loss of consciousness within one hour after the onset of symptoms. The mechanisms are the following: 1. ventricular fibrillation, 2. ventricular tachycardia and flutter with subsequent ventricular fibrillation, 3. torsade de pointe, 4. bradyarrhythmias and asystolic arrest. White the main risk factor is the presence of coronary artery disease, any organic or functional disease of the heart can predispose for sudden cardiac death. To evaluate the risk of sudden cardiac death noninvasive (Holter, echocardiography, exercise test and signal averaged (ECG) and often invasive (electrophysiological study) tests are necessary. The therapy is based on drugs (mainly beta blockers and amiodarone), coronary revascularization, catheter ablation techniques and the implantation of a cardioverter defibrillator; the latter appears to be the most promising approach.     

Sudden cardiac death in hypertrophic cardiomyopathy: risk evaluation

The pathophysiology of the lamb model of congenital diaphragmatic hernia (CDH) involves pulmonary hypoplasia, pulmonary hypertension, and surfactant deficiency. Inhaled nitric oxide (NO) is a highly selective pulmonary vasodilator. The aim of this study was to determine the effects of inhaled NO on pulmonary gas exchange, acid-base balance, and pulmonary pressures in a lamb model of CDH with or without exogenous surfactant therapy. At the gestational age of 78 days (full term, 145 days) 11 lamb fetuses had a diaphragmatic hernia created via a left thoracotomy and then were allowed to continue development in utero. After cesarean section, performed at term, six lambs received exogenous surfactant therapy (50 mg/kg, Infasurf) and five served as controls. All animals were pressure-ventilated for 30 minutes and then received 80 ppm of inhaled NO at an F1O2 of .9 for a 10-minute interval. Compared with the control lambs, the lambs with exogenous surfactant therapy had higher pH (7.17 +/- .06 v 6.96 +/- .07; P < .05), lower PCO2 (73 +/- 8 v 122 +/- 20, p < .05), and higher PO2 (153 +/- 38 v 50 +/- 23; P < .05). In control CDH lambs (without surfactant), inhaled NO did not improve pH, PCO2, or PO2, or decrease pulmonary artery pressure. In CDH lambs given exogenous surfactant, NO decreased pulmonary artery pressures (42 +/- 4 v 53 +/- 5; P < .005) and further improved PCO2 and PO2. NO also made the difference between pulmonary and systemic artery pressures more negative in the surfactant-treated lambs (-15 +/- 4 v -2.3 +/- 2.4; P < .005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Sudden unexpected cardiac death: methods and results of a national pilot survey

In order to develop a methodology for measuring the occurrence and circumstances of sudden unexpected adult deaths due to cardiac and to unidentified causes throughout England, a stratified random pilot sample of 12 of the 133 coroner's jurisdictions in England was invited to survey prospectively a quota sample of 78 consecutive white Caucasians, aged from 16 to 64 years, with no history of ischaemic heart disease, who were last seen alive within 12 h of being found dead, and for whom a coroner's post-mortem examination found either a cardiac or no identifiable cause of death. Eleven (92%) coroners participated. In a median of 105 days (range 21-169), 65 cases (83% of the quota) were ascertained (54 (83%) males). Of the ascertained cases, registration forms were received on 62 (95%), tissue specimens on 63 (97%), and post-mortem reports on 58 (89%). Death was witnessed in 58%, of which 35% were 'instantaneous'. The median time from symptom onset to death was 40 min. In unwitnessed deaths, the median time since last being seen alive was 90 min. Sixty-eight per cent of all deaths were attended--by a relative in 34%, passer-by (8%), ambulance crew (32%), nurse (11%), doctor (38%), and police (9%). Cardio-pulmonary resuscitation was attempted in 38 of the 42 attended deaths. Sixty-seven per cent were taken ill at home, 12% at work, 12% in a public place, and 10% elsewhere. The certified cause of death was ischaemic heart disease in 89%, in whom coronary thrombosis and/or myocardial damage was absent in 6 cases (9%). In the remainder, the certified cause was hypertensive heart disease (5%), hypertrophic obstructive cardiomyopathy (3%), 'cardiomegaly' (1.5%) and 'sudden cardiac arrhythmia' alone (1.5%). A retrospective audit of coroner's records revealed the median case ascertainment rate was 75%. This approach to surveying sudden unexpected adult death nationally resulted in a high response rate (92%) from coroners, consultant pathologists and their staff, the identification of a large proportion of eligible cases, and complete information in most of the identified cases. In from 2% to 15% of cases, death may have been either purely dysrhythmic or due to a sudden adult death syndrome.     

Sudden infant death syndrome: risk factor profiles for distinct subgroups

The authors investigated risk profiles of sudden infant death syndrome (SIDS) as a function of age at death. A case-control study carried out in the Tyrol region of Austria enrolled 99 infants who died of SIDS between 1984 and 1994 and 136 randomly selected controls. Early and late SIDS (< 120 days of age vs. > or = 120 days) were defined according to the clear-cut bimodal age-at-death distribution. Inadequate antenatal care, low parental social and educational level, and the prone sleeping position were risk conditions that applied to both early and late SIDS. A marked seasonal variation (winter preponderance) was the most outstanding feature of late SIDS. A gestational age of < 37 weeks (odds ratio (OR) = 8.4, 95% confidence interval (CI) 2.6-26.0), repeated episodes of apnea (OR = 5.7, 95% CI 1.2-27.0), low birth weight (< 2,500 g) (OR = 3.4, 95% CI 1.1-11.0), a family history of sudden infant death (OR = 2.9, 95% CI 1.1-7.5), and maternal smoking during pregnancy (OR = 2.2, 95% CI 1.0-4.5) were associated with early SIDS. This study identified two distinct subgroups of SIDS infants characterized by different risk conditions and ages at death. These results underline a multiple-cause hypothesis for SIDS etiology which involves a genetic predisposition, immaturity in the first months of life, and environmental factors acting at various ages.     

Risk factors for sudden unexpected cardiac death in Tasmanian men

Cerebral expression of the injury response cytokine transforming growth factor-beta 1 (TGF-beta 1) has been found to be increased in several neurological diseases but it remains unclear whether its function is primarily beneficial or detrimental. Here we show that transgenic (tg) mice that overexpress bioactive (TGF-beta 1 in the central nervous system (CNS) and show no overt phenotype in the unmanipulated state, are more susceptible to the immune-mediated CNS disease experimental autoimmune encephalomyelitis (EAE). TGF-beta 1 tg mice with EAE showed an earlier onset of clinical symptoms, more severe disease and increased mononuclear cell infiltration in their spinal cords compared with non-tg littermate controls with EAE. Whereas previous observations indicated that increased peripheral levels of TGF-beta 1 can suppress EAE, our findings demonstrate that local expression of TGF-beta 1 within the CNS parenchyma can enhance immune cell infiltration and intensify the CNS impairment resulting from peripherally triggered autoimmune responses.     

Sudden unexpected death in epileptics following sudden, intense, increases in geomagnetic activity: prevalence of effect and potential mechanisms

Abrupt, intense increases in global geomagnetic activity during the local night may precipitate a significant proportion of sudden unexpected (or unexplained) deaths (SUD) in epileptics. Over a 2-year period SUD in healthy chronic epileptic rats occurred when the average daily geomagnetic activity exceeded 50 nT (nanoTesla) and suddenly began during local night. Other experiments demonstrated that epileptic rats displayed more spontaneous seizures per night if there had been sudden increases in geomagnetic activity. Analyses of previously published data indicated that the number of SUDs/month in a population of human epileptics was positively associated with the number of days/month when the average geomagnetic activity exceeded 50 nT. The results support the hypothesis that suppression of the nocturnal concentrations of the endogenous anticonvulsant melatonin by sudden increases in geomagnetic activity may encourage fatal cardiac arrhythmias by uncoupling the insular/amygdaloid-paraventricular hypothalamic-solitary nucleus pathways.     

Sudden death due to recuperated ventricular fibrillation: Brugada syndrome?

We report a 47 years old male who was recuperated from a sudden death, and in whom the cardiological assessment showed a right bundle branch block and a fluctuating ST segment elevation V1 to V3. During the electrophysiological study, a polymorphic tachycardia and a ventricular fibrillation were induced. Procainamide administration enhanced ST segment alterations in right precordial leads, and isoproterenol normalized the EKG. All these disturbances are similar to the condition described by Brugada brothers. The patient was treated with an internal implantable defibrillator, without the use of antiarrhythmic drugs and is well after four months of follow up.     

Panel III: Behavioral risk factors related to chronic diseases in ethnic minorities.

This article reviews the evidence on 5 risk behaviors: cigarette smoking, dietary intake, being overweight, limited exercise, and alcohol consumption among African Americans, Asian/Pacific Islanders, Latinos, and Native Americans. Although there is little basis for believing that these high-risk behaviors are any less significant as contributors to chronic disease risk in any ethnic group, the limited information available, especially for Asian/Pacific Islanders and Native Americans, indicates that there may be significant within- and between-group differences in the prevalence of these behaviors. Therefore. some of the ethnic group differences in morbidity and mortality for chronic diseases are partly attributable to differences in behavioral risk profiles. Limited basic health behavior information on most ethnic minority groups delay the development of effective health promotion interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sudden death in the laboratory rat: cardiac function, sensory, and experiental factors in swimming deaths

Three reported charateristics of sudden death in the wild rat, (1) bradycardia, (2) decreased survival without whiskers, and (3) increased suvival with preexposure to the stressor, are demonstrated in the domestic rat. Differences in sudden death between wild and domestic rats are discussed as well as possible interpretations of the phenomenon.     

Histiocytoid cardiomyopathy: a cause of sudden death in infancy

We report the case of an infant aged of 14 months deceased of sudden death. The diagnosis of histiocytoid cardiomyopathy was made on a necropsic basis. The pathologic examination showed a cardiac hypertrophy characterized by yellowish areas with irregular outlines, disseminated in the myocardium, and made of histiocyte-like cells with foamy or granular cytoplasm. These cells reacted positively with desmin and myoglobin labels, and had rare and disorganised myofibrils in electron microscopy, proving their muscular origin. The illness affects infants and usually causes severe cardiac troubles leading to death without treatment. This case is the fourteenth associated with sudden death.     

Sudden death among 1,000 patients with myocardial infarction: incidence and contributory factors. KYSMI Study Group

Clinical indicators and the incidence of sudden death among 1,000 consecutive patients (816 males and 184 females) with myocardial infarction were investigated between 1983 and 1987 after coronary arteriography. Twenty-four patients died suddenly during a study period of 3.3 +/- 2.0 yrs. The yearly incidence of sudden death calculated by the Kaplan-Meier method was 0.7%, nearly half of the incidence of cardiac death (1.5%/yr). Univariate analysis demonstrated statistically significant differences in the number of cases with coronary thrombolysis in the acute phase, degree of coronary artery stenosis, the frequency and degree of congestive heart failure and angina in the acute and chronic phase, the presence of serious post-infarction arrhythmia, ejection fraction, recurrent myocardial infarction, and administration of digitalis and diuretics. between the sudden-death group and the cardiac and other patient groups. There was also a tendency to higher frequency of history of diabetes mellitus, presence of acute mitral regurgitation, nitrates and nicorandil treatment, and coronary artery bypass graft in the sudden-death group. Multivariate analysis revealed that digitalis and nitrates treatment and left anterior descending artery involvement were major contributing factors. Re-infarction, left ventricular ejection fraction, and nicorandil therapy were not significant and minor contributing factors. The incidence of sudden death increased with digitalis therapy (Odds' ratio of 9.59), and left anterior descending artery disease, and decreased with nitrates (0.34).     

Treated plasma cell lesions of bone with MRI signs of response to treatment: unexpected pathological findings

Two cases of treated plasma cell lesions of bone are reported for which contrast-enhanced MRI had suggested necrosis, based on lack of enhancement after gadolinium injection, and in which pathologic examinations revealed the presence of extensive viable neoplastic tissue. These cases highlight the need for cautious interpretation of contrast-enhanced MRI signs of response to treatment and inactivity of lesions in the setting of plasma cell neoplasms.     

Early death in dialysis patients: risk factors and impact on incidence and mortality rates

Patients who die within the first 90 days after beginning dialysis are not included in mortality rates and may be absent from incidence counts. To identify factors associated with mortality within 3 months of the initiation of dialysis for ESRD and to estimate the impact of early deaths on ESRD incidence and mortality rates, this study investigated 15,245 patients who began dialysis in Georgia, North Carolina, and South Carolina over a 5-yr period. Data were collected by dialysis facility staff and reported to an ESRD registry. Six percent of all new patients died within 90 days of dialysis initiation (32% of all deaths occurring in the first year of treatment). Characteristics independently associated with increased risk of early death included older age, white race, male gender, physical and nutritional impairment, smoking, and the presence of cancer, congestive heart failure, clinical depression, and history of myocardial infarction. Depending on race-gender group, age-adjusted mortality rates based on this cohort were underestimated by 3 to 12% when patients who died early were excluded. These results suggest that certain patient characteristics-some potentially modifiable-confer increased risk of early death, and that the systematic exclusion of patients who die early from the U.S. national registry substantially influences ESRD mortality rates.     

Language and symbolic play in infancy: Independent or related abilities.

Investigated 3 hypotheses: that language and symbolic play are positively related in infancy, that the 2 are unrelated, and that early symbolic play predicts later language ability. 25 infants were observed in 2 free play sessions, at 12–14 mo (Session 1) and 20–22 mo (Session 2). Three symbolic play and object use measures were significantly and positively interrelated. Three language variables, measured at Session 2, were significantly and positively interrelated. There were no significant correlations between the language and play variables from either session, and a principal-components analysis confirmed this independence. The results best support the hypothesis that language and symbolic play abilities are unrelated in infancy. (French abstract) (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)