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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cardiac prognosis of hypertensive patients has been able to be precisely determined over the last 20 years as a result of large-scale epidemiologic surveys. The incidence of ischemic heart disease and the importance of left ventricular hypertrophy have been clearly defined in the literature. In contrast, the incidence of sudden death and ventricular arrhythmias has been poorly taken into account, although hypertension increases the risk of sudden death to the same degree as coronary artery disease. The relative risk increases progressively as a function of the quintiles of distribution of blood pressure, reaching a value of 3.2 for the highest quintile. There is also a significant correlation between hypertension and ventricular arrhythmias. Hypertensive subjects with other cardiovascular risk factors such as hypercholesterolemia or smoking and with ventricular extrasystoles, reflecting the presence of silent ischemia, can be considered to be at high risk of cardiac death.
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PMID:Cardiac prognosis in hypertensive patients. Incidence of sudden death and ventricular arrhythmias. 334 89

Numerous technologic advances have greatly facilitated the noninvasive analysis of right ventricular function. Nevertheless, important clues continue to be available to the astute clinician by physical examination. The chest x-ray is of rather limited utility. The electrocardiogram can show evidence of right atrial enlargement or right ventricular hypertrophy. Unfortunately, both sensitivity and specificity are deficient. Echocardiography is a widely available and potentially very accurate source of information concerning right ventricular dysfunction. Careful temporal analysis of the M-mode echocardiogram can give information beyond chamber size and wall thickness. Two-dimensional echocardiography allows more accurate determination of chamber size and wall thickness and also permits analysis of segmental wall motion and chamber contour. Doppler echocardiography allows measurement of pressure differences and flow kinetics. Preliminary data indicate that one can accurately assess pulmonary artery pressure and possibly right ventricular diastolic function. Color-flow mapping allows for accurate determination of valvular regurgitation and enhances the accuracy of standard Doppler echocardiographic techniques. Radionuclide analysis of the right ventricle by blood-pool imaging allows accurate determination of ejection fraction and wall motion. In addition, it may be possible to estimate pulmonary artery pressure. Use of short-acting radionuclides allows for serial imaging of the right ventricle after pharmacologic intervention or exercise. Perfusion scanning can show evidence of exercise-induced ischemia, although applicability to the right ventricle is somewhat limited. Avid scanning allows localizing of myocardial injury to the right ventricle. CT scanning of the heart is of limited clinical utility, because cardiac motion occurs too rapidly for accurate imaging. The advent of the cine-CT may overcome this problem and allow evaluation of right ventricular volumes and wall motion. Digital subtraction imaging allows for accurate video densitometric calculation of ejection fractions, but offers no advantage over other currently available techniques. Magnetic resonance imaging may prove to be the methodology of choice for analysis of right ventricular function, because it can give accurate measurement of right ventricular wall motion, ejection fraction, and (similar to Doppler flow studies) some indication of flow within the right-sided chambers. It will soon be possible to generate information concerning the biochemical content of the right ventricular myocardium, perhaps providing early evidence of hypertrophy or myopathy.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Noninvasive evaluation of right ventricular function. 355 88

The first electrocardiogram obtained on presentation for suspected myocardial infarction was examined for its usefulness in predicting clinical course and facility use. We studied 221 patients consecutively admitted to a nonuniversity hospital coronary care unit. High-risk patients were identified if the electrocardiographic diagnoses included myocardial infarction, ischemia, left ventricular hypertrophy, left bundle-branch block, or paced rhythm. These 63 patients (29% of total) had significantly greater incidences of serious events, need for procedures, and death than low-risk patients whose initial electrocardiograms did not carry the above diagnoses. Patients with a low-risk initial electrocardiogram may not require the facilities of a coronary care unit and perhaps could be safely observed in an intermediate care area. However, many hospitals do not have an intermediate care facility available, and in those that do, daily costs may not be markedly different than for treatment in a coronary care unit. Whether these low-risk patients could be safely treated in general medicine beds, where potential cost savings would be much greater, is unknown.
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PMID:The initial electrocardiogram during admission for myocardial infarction. Use as a predictor of clinical course and facility utilization. 357 37

In patients with varying degrees of chronic obstructive pulmonary disease (COPD), simultaneous measurements of central hemodynamics and left ventricular radionuclide ventriculograms at rest and during exercise were made. In 21 of these patients, satisfactory echocardiograms could be performed. In seven of the patients, arterial blood pressure at rest was increased. Decreased compliance of the left ventricle was thought to be present in patients with COPD and additional arterial hypertension. The left ventricular ejection fraction (LVEF) at rest was in the high normal range in all patients. During exercise, no further increase was observed. This pattern of LVEF response seems to be typical in patients with COPD. Because the highest values were observed in the more severe COPD and right ventricular hypertrophy, it is unlikely that an impairment of left ventricular function is caused by COPD. In five of 27 patients, an abnormal decrease of LVEF and regional hypokinesis occurred during exercise, thus suggesting additional coronary heart disease. The fact that at least 30% of the patients with COPD suffered from arterial hypertension and 20% of the patients exhibited unexpected ischemia detected by regional hypokinesis in RNV during exercise, but not in the ECG, may be of practical relevance. Coronary angiography was not indicated because most of these patients were over 65 and the factor limiting the working capacity was ventilatory impairment and not angina pectoris, in all patients. For this reason, a diagnostic uncertainty remains with regard to additional coronary heart disease in the older patients with advanced chronic obstructive pulmonary disease.
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PMID:Left heart function in chronic obstructive lung disease. 371 12

We evaluated ischemia-induced cellular electrophysiologic abnormalities in chronic pressure overload ventricular myocardium in vitro. Left ventricular systolic hypertension was induced in cats via partial supracoronary aortic constriction (overload); at 1 1/2-3 months, resulting pressure overload was accompanied by ventricular hypertrophy (25-35% by weight) and patchy endocardial fibrosis. Two hours of subsequent acute myocardial ischemia (ischemia) was imposed on overload (ischemia/overload) via total occlusion of distal branches of the left coronary artery system. Spontaneous premature depolarizations in vitro were increased in ischemia/overload compared to control, ischemia or overload alone; bursts of spontaneous, repetitive depolarizations were also unique to these preparations. Multiple site recordings of endocardial transmembrane action potentials overlying the borders (interface) of fibrotic areas in ischemia/overload demonstrated numerous electrophysiologic abnormalities, including several not observed in control, ischemia or overload. Unique to the border areas of ischemia/overload preparations was the presence of maintained but depressed resting potential without action potentials; also, the incidence of depolarizations at the onset of the plateau phase was highest in these preparations. In non-fibrotic areas, electrophysiologic properties including resting potential and action potential amplitude and rate of rise were diminished in ischemia/overload compared to ischemia or overload preparations. These data demonstrate that acute myocardial ischemia in the setting of chronic pressure overload leads to additional cellular electrophysiologic abnormalities compared to ischemia or overload alone.
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PMID:Cellular electrophysiology of coronary artery ligation in chronic pressure overload. 381 32

We evaluated the initial electrocardiogram as a predictor of complications in 469 patients with suspected acute myocardial infarction. An electrocardiogram was classified as positive if it showed one or more of the following: evidence of infarction, ischemia, or strain; left ventricular hypertrophy; left bundle-branch block; or paced rhythm. Forty-two (14 per cent) of 302 patients with positive electrocardiograms had at least one life-threatening complication (ventricular fibrillation, sustained ventricular tachycardia, or heart block), as compared with 1 (0.6 per cent) of 167 patients with a negative electrocardiogram. Life-threatening complications were therefore 23 times more likely if the initial electrocardiogram was positive (P less than 0.001). Other complications were 3 to 10 times more likely (P less than 0.01), interventions were 4 to 10 times more likely (P less than 0.05), and death was 17 times more likely (P less than 0.001) in patients with a positive electrocardiogram. We conclude that patients with a negative initial electrocardiogram have a low likelihood of complications and could be admitted to an intermediate care unit instead of a coronary care unit. This would reduce admissions to the coronary care unit by 36 per cent and thereby save considerable hospital costs without compromising patient care.
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PMID:Use of the initial electrocardiogram to predict in-hospital complications of acute myocardial infarction. 392 May 20

This report tests the hypothesis that, in early diastole, motion of the anterior left atrial wall corresponds to the motion that can be observed in the contiguous posterior wall of the aortic root. To test this hypothesis, we examined the effects of mitral stenosis, exercise in normals, exercise induced left ventricular ischemia, left ventricular hypertrophy and left ventricular dysfunction on this slope. Each altered early diastolic atrioventricular interaction as predicted and therefore, the early diastolic motion of the anterior left atrial wall does appear to be mirrored by the early diastolic slope of the posterior wall of the aortic root. Consequently, if interpreted in the clinical context, measurement of early diastolic slope of the posterior wall of the aortic root may serve as a useful guide to separate patients with severe from those with mild mitral stenosis.
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PMID:Early diastolic posterior aortic root slope, a clinical guide to the severity of mitral stenosis. 403 Oct 2

A survey was made on a population of 6059 subjects aged more than 60 years with the aim to assess 1. the prevalence of heart arrhythmias and 2. the relationships between arrhythmias and some other ecg alterations. Arrhythmias resulted present in 29.0% of the whole population with a significantly higher prevalence among males (30.7% vs 28.1%, P less than 0.05) and among subjects over 75 years of age (33.2% vs 23.9%, P less than 0.001). Supraventricular extrasystoles (SE, 11.55%), atrial fibrillation (AF, 10.44%) and ventricular extrasystoles (VE, 8.91%) were the most frequent arrhythmias, followed by sinus bradycardia (SB, 2.04%), sinus arrhythmia (SA, 1.35%), atrial flutter (AFL, 1.09%) and junctional rhythms (JR, 0.20%). AF and AFL resulted significantly more frequent among females, whilst SE, VE and SB were more frequent among males. All the above arrhythmias, with the exception of AFL and JR resulted significantly more frequent among subjects over 75. A significantly higher prevalence of ecg signs of left ventricular hypertrophy, ischemia, previous myocardial infarction (MI) and of the so-called "minor" T-wave changes (MTC) was found among the subjects with arrhythmia as compared with those free from rhythm disturbances. Ecg signs of MI and MTC were significantly more frequent among males and MTC were more frequent among females and among subjects over 75. It is concluded that in an old person the presence of an arrhythmia should lead to a careful evaluation of the general and cardiological clinical situation in order to avoid 1. to prescribe an unnecessary and potentially dangerous antiarrhythmic treatment, and 2. to misdiagnose an underlying clinical condition liable to a decisive improvement under adequate treatment.
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PMID:[Arrhythmias in the elderly]. 619 Jan 9

It is frequently stated that hypertrophied ventricles tolerate ischemia less well than nonhypertrophied ventricles. The authors' earlier studies in a rat supravalvular aortic stenosis model and canine valvular aortic stenosis model, both with concentric left ventricular hypertrophy, disclosed accelerated rates of ischemic contracture and diminished basal myocardial high energy phosphate stores. These studies have been extended to ten patients with severe left ventricular hypertrophy caused by valvular aortic stenosis and normal coronary arteries. ATP (endocardial and epicardial) from transmural left ventricular biopsies taken at operation before aorta cross-clamping, and frozen immediately in liquid nitrogen, were compared with similar biopsies from patients with nonhypertrophied myocardium supplied by normal coronary arteries. The subendocardial high energy phosphate levels in the nonhypertrophied myocardium was greater than high energy phosphate levels in the subepicardium of nonhypertrophied ventricles (ATP-micromoles/gram-protein, epi = 36.8 +/- 3.3, endo = 37.7 +/- 3.3) (p = NS). However, in the hypertrophied myocardium the subendocardium consistently showed significantly depressed high-energy phosphate levels when compared with subepicardial levels (ATP-hypertrophied myocardium, epi = 31.5 +/- 1.6, endo = 25.9 +/- 1.7) (p less than 0.05). This uniform depression of ATP stores, greatest in the subendocardium, in left ventricular hypertrophy suggests a common biologic mechanism for the enhanced sensitivity to ischemia. Of importance for patients may be the prior observation in rats that repletion of ATP( stores before ischemia eliminates the accelerated rate to ischemic contracture. Diminished subendocardial ATP stores appear to be an intrinsic property of severely hypertrophied myocardium and probably contribute to its enhanced sensitivity to ischemia.
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PMID:Depressed high-energy phosphate content in hypertrophied ventricles of animal and man: the biologic basis for increased sensitivity to ischemic injury. 621 20

Seventeen hypertensive patients with EKG evidence of left ventricular hypertrophy and subendocardial ischemia were studied. The following tests were performed: cine-ventriculography, coronary arteriography, ejection fraction, ventricular pressures, left ventricular mass, EKG stress test and atrial stimulation. In 10 cases cardiac scintigraphy with intracoronary injection of albumin-macro-aggregates marked with TC 99m, was obtained. EKG stress and atrial stimulation tests were positive in all cases, with ST depression greater than 1mm, or accentuation of previous ST depression. 83.7% of the patients had permeable coronary arteries, with "corkscrew' tortuosity. Left ventricular mass was increased in all cases (119 +/- 28.5% m2 s/c). Ejection fraction (74.2 +/- 8.1), and left ventricular diastolic pressures were normal. Cardiac scintigraphy showed uniform distribution of the radioisotope in the right ventricle and poor concentration with better dispersion and distribution in the left ventricle. It is concluded that subendocardial ischemia in these subjects is not produced by obstruction of the main coronary trunks and is associated to a significant increment of left ventricular mass which possibly produce a poor coronary reserve, and a potentially high risk condition.
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PMID:[Myocardial ischemia in hypertension heart disease (author's transl)]. 621 25


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