Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The features of ventricular arrhythmia in coronary spasm induced by ergonovine were examined to elucidate the characteristics of ventricular arrhythmia in acute myocardial ischemia. The coupling intervals and configurations of the QRS wave of the premature ventricular beats (PVBs) were extremely variable, even in the same individual and at the closer time phases. The prematurity index (R-R'/QT) of PVBs with the right bundle branch block (RBBB) pattern was significantly smaller than with the left bundle branch block (LBBB) pattern. The vulnerability index (R-RX QT/R-R') of PVBs with the RBBB pattern was significantly larger than with the LBBB pattern. The incidence of PVBs with the RBBB pattern (50.4%) was slightly larger than with the LBBB pattern (40.5%). PVBs deteriorated into ventricular tachycardias (VTs) in 29 (24.8%) of 117 cases with the RBBB pattern and in 11 (11.7%) out of 94 cases with the LBBB pattern. Thus, PVBs with the RBBB pattern were more likely to progress to VT than with the LBBB pattern. But it is difficult to assess the clinical significance of PVBs from their QRS morphology alone, because 11 (27.5%) of 40 cases of VT were initiated by PVBs with the LBBB pattern.
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PMID:Morphology of ectopic ventricular beats and their relationship to ventricular tachycardia in acute myocardial ischemia. 240 7

Twenty-four-hour Holter ECGs were recorded in 1089 patients. Ventricular tachycardia (VT) was observed in 184 tapes obtained from 81 patients (73 men and 8 women). Underlying heart diseases were present in 72 patients and no organic heart diseases were found in nine patients. The analysis of continuous 1-hour rhythm strips immediately before VT revealed that, in ischemic heart disease and hypertrophic cardiomyopathy, there was no correlation between the incidence of VT and the number or complexity of premature ventricular complexes (PVCs) within 1 hour before VT. In contrast, frequent or multiform PVCs were often observed during the pre-VT period in the patients with rheumatic heart disease or dilated cardiomyopathy. These findings suggest that the mechanism of VT may be different among the various underlying heart diseases. In addition, the mode of initiation of VT was evaluated. Only few episodes of VT occurred with the prematurity index value smaller than 1.0 or the vulnerability index value greater than 1.1. The correlation between the rate of VT and the preceding sinus rate was not significant, and the correlation between the rate of VT and the coupling interval of VT was weak. These facts suggest that the malignancy of VT, represented by the rate of VT, cannot be predicted by the preceding sinus rate or by the coupling interval of VT.
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PMID:Prevalence of ventricular tachycardia in patients with different underlying heart diseases: a study by Holter ECG monitoring. 372 86

The electrocardiographic responses to programmed ventricular stimulation and acute posterolateral myocardial ischemia were studied in conscious dogs treated with the resolved optical isomers of sotalol. Studies were conducted 3-7 days after anterior myocardial infarction to determine the relative contributions of beta-adrenergic receptor blockade and direct Class III electrophysiologic actions in the antiarrhythmic and antifibrillatory actions of the isomers. With cumulative i.v. administration of up to 8 mg/kg, both the beta-blocking levorotatory isomer and the dextrorotatory isomer suppressed the induction of ventricular tachyarrhythmias by programmed stimulation in at least 50% of dogs tested. Both isomers produced equivalent 15-20% increases in normal zone ventricular refractoriness, thereby preventing propagation of programmed ventricular extrastimuli of sufficient prematurity to elicit tachyarrhythmias. The levorotatory isomer of sotalol prolonged the PR interval; the administration of the dextrorotatory isomer increased QTc and, in several dogs, was associated with the development of ventricular ectopy. The prior administration of 8 mg/kg of either optical isomer of sotalol prevented the immediate spontaneous development of ventricular fibrillation in response to ischemia at a distance from the previous site of infarction. These results suggest that alterations in ventricular refractoriness may underlie the antiarrhythmic and antifibrillatory actions of the optical isomers of sotalol and of racemic sotalol.
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PMID:Antiarrhythmic and antifibrillatory actions of the levo- and dextrorotatory isomers of sotalol. 608 71

Eighteen open chest dogs anesthetized with pentobarbital sodium were studied to determine the role of early cycle premature ventricular beats in the initiation of ventricular tachycardia and fibrillation during the initial 30 minutes of acute myocardial ischemia. The coupling interval and prematurity index (R-R'/R-R) of every premature beta after a sinus beat were determined during both the "immediate" (2 to 12 minutes) and "delayed" (13 to 30 minutes) phases of ventricular arrhythmias that follow acute coronary ligation. During the immediate phase, characterized by marked fractionation of local electrograms and delayed intramyocardial conduction, early cycle beats were infrequent (8 percent of extrasystoles) and initiated only 3 (4 percent) of 75 episodes of ventricular tachycardia and fibrillation. However, during the delayed phase, characterized by less fractionation and more uniform conduction, early cycle beats were both more frequent (24 percent of extrasystoles, p less than 0.001) and more successful (20 [34 percent] of 59 episodes, p less than 0.001) in initiating ventricular tachycardia and fibrillation. Thus, the underlying electrophysiologic derangements appeared to be of primary importance in determining both the frequency and relative malignancy of early cycle beats during acute myocardial ischemia.
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PMID:Role of early cycle ventricular extrasystoles in initiation of ventricular tachycardia and fibrillation: evaluation of the R on T phenomenon during acute ischemia in a canine model. 617 40

The purpose of this investigation was to determine whether ventricular ectopic beats, or ventricular premature beats (VPBs), on routine electrocardiograms in men without apparent heart disease predict the later occurrence of clinical manifestations of ischemic heart disease (IHD). The Manitoba Study cohort consisted of 3983 men predominantly between 25 and 34 years of age and free of IHD at entry. During the 29-year observation period, 401 persons without clinical evidence of heart disease had VPBs on an electrocardiogram at a routine examination. They were followed 10.8 +/- 0.5 (SEM) years and 13.5% (54 men) later manifested IHD. Age-specific total IHD incidence was significantly (p less than 0.05) greater for men 40 to 59 years of age at VPB occurrence compared to men of the same age without VPBs. The clinical manifestation with the strongest association with VPBs was sudden death. VPB characteristics of frequency, configuration, coupling interval, and postextrasystolic T-wave change did not distinguish those who developed IHD. Prematurity index (R-R'/QT) showed a trend toward an association of late coupled ectopic beats (R-R'/QT greater than 1.6) and IHD risk. However, faster basic ventricular rate plus VPBs significantly correlated with greater IHD probability. Thus ventricular ectopic beats on a routine electrocardiogram in men over 40 years of age without apparent heart disease identify those at high risk for a clinical IHD event, especially sudden death.
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PMID:Relationship of ventricular ectopy in men without apparent heart disease to occurrence of ischemic heart disease and sudden death. 746 14

Prematurity and low birth weight (LBW) cause hypertension (HTN), ischemic heart disease, and obesity in young adults. The objective of the study was to identify risk factors for the development of HTN in children born preterm or at a LBW and to assess pediatricians' awareness of the problem. A retrospective review of 160 cases was conducted. In total, 22% of babies born preterm/LBW developed HTN by age 15 years. The odds of developing HTN were 1.6 times greater for every one standard deviation increase in body mass index. Higher risk posses for those born small for gestational age and under 1000 g. Of the 35 cases of HTN identified, only 31% were recognized as abnormal by the primary care providers. The development of obesity and HTN appear related in preterm/LBW children. Awareness of prematurity or LBW as a risk factor for HTN should be raised among pediatric primary care providers.
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PMID:Can we predict hypertension among preterm children? 2164 52

Intrauterine growth restriction (IUGR) is when fetuses and newborn infants have not reached their true growth potential as genetically defined. Fetuses with IUGR develop in a less than ideal environment that leads to epigenetic changes and marks infants' metabolism for the rest of their lives. Epigenetic changes affect insulin-like growth factor-1 (IGF-1) levels and lead to insulin resistance and ultimately to a metabolic syndrome. The metabolic syndrome is a constellation of illnesses that raise one's risk for type 2 diabetes mellitus, coronary artery disease, and ischemic heart disease, including hypertension, dyslipidemia, central obesity, insulin resistance, and inflammation. The association between IUGR or prematurity and long-term insulin resistance, obesity, hypertension, and metabolic syndrome remains unclear. While studies have shown an association, others have not supported such association. If alteration of intrauterine growth can ultimately lead to the development of metabolic derangements in childhood and adulthood, and if such association is true, then early interventions targeting the health of pregnant women will ensure the health of the population to follow.
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PMID:Prevalence of diabetes and obesity in association with prematurity and growth restriction. 2874 Apr 12