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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although hypertension is associated with increased risk of sudden cardiac death, the mechanisms involved remain enigmatic. Little is known about hemodynamic and plasma catecholamine concentration changes during coronary artery occlusion in hypertensive subjects. To study this, 30 pigs were implanted with catheters in the aorta and a silk snare around the left anterior descending coronary artery that could later be pulled to permanently occlude the artery. Perinephritic hypertension was induced in 14 of the animals over 3 weeks by wrapping one kidney in silk followed by contralateral nephrectomy. Coronary artery occlusion (CAO) was carried out in all pigs in the conscious resting state. Ventricular fibrillation (VF) developed in 50% of each group within 15 min after coronary artery occlusion. The hypertensive VF group showed an increase in norepinephrine concentration of 112 +/- 46%; a significantly greater increase than the intact VF group, which showed a 29 +/- 7% increase in norepinephrine concentration 5 min after coronary artery occlusion (p < 0.05).
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PMID:Plasma norepinephrine increased during coronary occlusion in hypertensive pigs that developed ventricular fibrillation. 897 45

To assess the efficacy of losartan (2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H-tetrazol-5-yl)biphe nyl-4-yl)methyl]imidazole, potassium salt), an angiotensin II receptor antagonist, on acute myocardial ischemia, 36 four-month-old spontaneously hypertensive rats were used. The animals underwent 45 min of left coronary artery occlusion and 1 h of reperfusion and were randomly assigned to control and losartan-treated groups (2, 5, and 10 mg/kg, intravenously). Losartan was administered 15 min before ischemia. Electrocardiograms (lead II) were monitored continuously throughout the experiment. To assess the anti-infarct effect of losartan, the area at risk was determined by methylene blue dye and the infarct size was determined by nitroblue tetrazolium chloride staining. The areas of risk and infarct were measured by computerized planimetry. Results demonstrated that the low and intermediate doses (2 and 5 mg/kg) of losartan significantly decreased the incidence of ventricular fibrillation and mortality during the ischemic period induced by left coronary artery occlusion. However, a significant reduction in infarct size, calculated as a percentage of the area at risk, was noted in all three losartan-treated groups (control: 41.5% +/- 5.2%, losartan, 2 mg/kg: 11.2% +/- 5.8%, 5 mg/kg: 8.5% +/- 2.7% and 10 mg/kg: 13.7% +/- 1.6%). The results suggest that losartan may be useful in the treatment of ventricular arrhythmias induced by acute myocardial infarction and attenuation of reperfusion injury in hypertension.
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PMID:Losartan attenuates myocardial ischemia-induced ventricular arrythmias and reperfusion injury in spontaneously hypertensive rats. 927 79

A 73-year-old man presented with pain in lower limbs, lower abdomen, and anterior chest. His past medical history includes inferior myocardial infarction 3 years ago and hypertension. Electrocardiogram revealed ST elevation in II, III, and aVF indicating inferior myocardial reinfarction and angiography showed abdominal aortic embolism. Axillobifemoral bypass was performed urgently under general anesthesia. Because the patient developed acute renal failure and furosemide did not show diuretic effect, hemodialysis was used. The patient needed circulatory support with dopamine, dobutamine, epinephrine, and lidocaine intraoperatively. Approximately 90 minutes after the start of the operation, the patient developed ventricular fibrillation. The cardiac rhythm returned to normal after 2 minutes of cardiopulmonary resuscitation. The operation was performed successfully. An increase in serum potassium and metabolic acidosis were not noted postoperatively. However, weaning from the catecolamines was very difficult, and the patient died on 29th postoperative day. In this case, we employed general anesthesia without epidural anesthesia, because intraoperative hypotension might be the major cause for perioperative cardiac complications. Increase in serum potassium and myoglobin and metabolic acidosis were reported to occur after revascularization. Because the patient developed acute renal failure, intraoperative hemodialysis was valuable for preventing adverse effects due to reperfusion.
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PMID:[Perioperative management for acute abdominal aortic obstruction in a patient with acute myocardial reinfarction associated with acute renal failure]. 931 Dec 11

Spontaneously hypertensive rats (SHR) with ventricular hypertrophy show an increased vulnerability for the development of potentially lethal ventricular arrhythmias such as ventricular fibrillation (VF). The mechanisms of this increased vulnerability are not fully understood but may be related to abnormal intracellular Ca2+ ([Ca2+]i) handling under stress conditions. We therefore investigated whether [Ca2+]i handling is abnormal in hypertrophied hearts of SHR without heart failure during stimulation stress, and if so whether abnormal [Ca2+]i handling is a determinant of the increased vulnerability to VF in SHR. [Ca2+]i was measured by indo-1 surface fluorescence in perfused hearts of 8- to 10-month-old control Wistar-Kyoto rats (WKY) and age-matched SHR. The state of [Ca2+]i handling was analyzed during three different forms of stimulation stress: rapid pacing, the long rest period after cessation of rapid pacing, and preprogrammed ventricular stimulation that was simultaneously used for the determination of VF threshold. The pulse number VF threshold was used as an index to determine vulnerability to VF and to analyze the relationship of [Ca2+]i handling to vulnerability. Although VF thresholds were lower in SHR than in WKY, we found that both demonstrated similar [Ca2+]i handling during stimulation stress. The extent and rate of [Ca2+]i accumulation during rapid pacing and those of the [Ca2+]i decline after cessation of pacing were similar in SHR and WKY. In addition, the relationship between [Ca2+]i and VF threshold was unaltered in SHR. Thus, we conclude that [Ca2+]i handling is normal in hypertrophied hearts of SHR without heart failure during stimulation stress and that it is not a determinant of the increased vulnerability to VF in SHR.
Hypertension 1997 Sep
PMID:Intracellular Ca2+ handling and vulnerability to ventricular fibrillation in spontaneously hypertensive rats. 931 33

beta-Adrenoceptor antagonists (beta-blockers) reduce mortality and recurrent myocardial infarction (MI) in older patients after both Q-wave MI and non-Q-wave MI. The effects of beta-blockers are to: (i) reduce complex ventricular arrhythmias, including ventricular tachycardia; (ii) increase the ventricular fibrillation threshold; (iii) reduce myocardial ischaemia; (iv) decrease sympathetic tone; (v) markedly attenuate the circadian variation of complex ventricular arrhythmias: (vi) abolish the circadian variation of myocardial ischaemia; and (vii) abolish the circadian variation of sudden cardiac death or MI. beta-Blockers reduce mortality in patients with MI and complex ventricular arrhythmias. In addition, they are excellent antianginal agents. Older persons with hypertension who have had an MI should be treated initially with a beta-blocker. beta-Blockers reduce mortality in patients with: (i) diabetes mellitus who have had an MI; (ii) MI and congestive heart failure with an abnormal or normal left ventricular ejection fraction; and (iii) MI and an asymptomatic abnormal left ventricular ejection fraction. Severe congestive heart failure, severe peripheral arterial disease with threatening gangrene, greater than first degree atrioventricular block, hypotension, bradycardia, lung disease with bronchospasm, and bronchial asthma are contraindications to treatment with beta-blockers.
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PMID:Postinfarction use of beta-blockers in elderly patients. 941

The aim of this study was to describe mortality, mode of death and risk indicators for death during 5 years of follow-up among men and women coming to the emergency department with chest pain or other symptoms raising suspicion of acute myocardial infarction (AMI). During the 21 months of the study, all patients who came to the medical emergency department of one single hospital with chest pain or other symptoms suggestive of AMI were prospectively followed for 5 years. A total of 5362 patients came on 7157 occasions; men accounted for 55% of the admissions. The 5-year mortality rate was 25.6% for men compared with 25.7% for women. The women were older and had a higher prevalence of known congestive heart failure and hypertension, whereas the prevalence of previous myocardial infarction was higher in men. When correcting for dissimilarities in age and clinical history, male gender appeared as an independent predictor of death. In terms of mode of death men differed from women: more frequently dying at home, more frequently dying in association with ventricular fibrillation and less frequently dying in association with congestive heart failure. However, these differences were to some extent explained by differences in age. Independent risk indicators for death during 5 years of follow-up differed in men and women. It was concluded that in a consecutive series of patients with chest pain or other symptoms suggesting AMI in the emergency department, male gender was an independent risk indicator for death during a 5-year follow-up. This might be explained by a higher occurrence of coronary artery disease in men than in women in this patient population.
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PMID:Long-term prognosis in men and women coming to the emergency department with chest pain or other symptoms suggestive of acute myocardial infarction. 944 3

Coronary venous hypertension induced by partial coronary sinus obstruction (CSO) in the dog, prevents or delays the predictable ventricular fibrillation (VF) of the early phase of acute ischemia. Also, CSO acting presumably through enhanced myocardial hydration, normalizes the inhomogenous extracellular potassium ([K+]o) accumulation, a major factor in producing the electrophysiological disparities, characteristic of arrhythmogenic substrate. To further clarify the mechanism of early ischemic VF prevention in dogs, radioactive microspheres were used to evaluate regional perfusion changes, resulting from CSO sufficient to raise the coronary sinus pressure to 40 mmHg, before and during ischemia induced by double coronary artery occlusion (CAO) (n=5). Also, global or regional unipolar electrogram mapping was used to assess changes of epicardial ventricular activation times (AT) and sequence and activation recovery intervals (ARI) during CSO, CAO and combined CSO and CAO, induced in random order (n=8). CSO did not affect regional perfusion nor improved collateral blood flow during ischemia. With CSO, AT shortened modestly over time (0.41+/-1.1 ms/min, r=0.85, P<0. 05) and ARI transiently decreased by up to 5.5%. With CAO, AT became variably delayed and isochrone map distortions were indicative of localized conduction delays or blocks, consistent with elevated [K+]o. In contrast, when CAO was preceded by CSO, AT delays were homogenous and normal activation sequence was preserved. Also, whereas with CAO, ARI shortened unequally over the ischemic region by as much as 43% at individual sites (average of 38.3+/-6.8 ms, P<0. 001), with combined CSO and CAO, ARI shortening was less pronounced and more homogenous (26.1+/-5.6 ms, P<0.05), not exceeding 29% at any site. Thus, in accordance with previous findings of enhanced [K+]o homogeneity, coronary venous hypertension reduces the disparities of activation and refractoriness of ischemia attributable, at least in part, to disparate [K+]o accumulation. Since no collateral blood flow improvement could be identified, the salutary electrophysiological effects of CSO may reflect a more homogenous extracellular environment, due to preservation of normal microvascular pressure (Pmv) and sustained filtration and lymph flow.
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PMID:Coronary venous hypertension prevents the formation of the electrophysiological arrhythmogenic substrate of acute ischemia in the dog: salutary effects of preserved myocardial hydration. 951 2

We compared the angiographic findings, coronary risk factors and five years prognosis in 200 patients < or =45, and 260 patients >45 years old who where admitted with an acute myocardial infarction. We found that family history and smoking were the most common risk factors in patients < or =45 years old P<0.04, P<0.0001, respectively, and hypertension and diabetes mellitus were more prevalent in patients >45 years, P<0.00001 for both. Young patients had a higher incidence of normal coronary arteries and a lesser one of triple vessel disease in comparison with old ones P<0.001 and P<0.04, respectively. There was also a tendency for young patients to have a higher frequency of single vessel disease. The long-term prognosis was favourable in the younger age group since the survival rate was much better, as well as the quality of life. Death in the young patients seems to be very often electrical owing to sudden ventricular fibrillation, whereas death in the elderly is more often associated with congestive heart failure.
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PMID:Comparison of angiographic findings, risk factors, and long term follow-up between young and old patients with a history of myocardial infarction. 988 Feb 3

The combination of a calcium antagonist with an angiotensin-converting enzyme (ACE) inhibitor is increasingly used in the therapy of hypertension, but there are no experimental data supporting the use of this combination in acute myocardial ischemia and reperfusion. We tested the effects of oral pretreatment in a pig model, paying special attention to arrhythmias and adverse hemodynamic effects. Pigs received verapamil 240 mg + trandolapril 4 mg, verapamil 240 mg, or placebo orally once daily for 10 days, after which a coronary artery was ligated for 20 minutes and then allowed to reperfuse. The ventricular fibrillation threshold (VFT) was measured during ischemia to assess the vulnerability of the heart to ventricular fibrillation, whereas spontaneous tachyarrhythmias were monitored during reperfusion. Regional left ventricular (LV) blood flow was measured with radioactive microspheres. During the ischemic period, both the combination of verapamil plus trandolapril, and verapamil alone, prevented a fall in the VFT, indicating antiarrhythmic activity. The combination maintained LV contractile activity and cardiac output (CO) at preligation levels, whereas verapamil alone decreased cardiac output. During reperfusion, verapamil plus trandolapril prevented spontaneous ventricular tachyarrhythmias and increased blood flow in the reperfused zone. In contrast, verapamil was not antiarrhythmic and decreased CO. Thus the addition of the ACE inhibitor trandolapril to the calcium antagonist verapamil resulted in antiarrhythmic activity during ischemia and reperfusion, and produced a better hemodynamic profile.
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PMID:Combination of a calcium antagonist, verapamil, with an angiotensin converting enzyme inhibitor, trandolapril, in experimental myocardial ischemia and reperfusion: antiarrhythmic and hemodynamic effects of chronic oral pretreatment. 992 75

Patients with primary aldosteronism often present with hypokalemia and hypertension. Primary aldosteronism presenting as sudden death due to ventricular fibrillation is described in an otherwise healthy 37-year-old woman. After successful direct current cardioversion, serum potassium was 1.4 mmol/L. Investigations revealed a suppressed renin level, elevated serum aldosterone and a right adrenal nodule found on imaging. Ventricular fibrillation has not previously been described as a presention of a biochemically and surgically proven aldosterone-producing adenoma. This case highlights the importance of early detection and proper diagnosis of secondary hypertension before serious sequelae occur.
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PMID:Ventricular fibrillation: an extreme presentation of primary hyperaldosteronism. 1020 99


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