Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An attempt was made to determine the effect of hypothermic potassium cardioplegia (35 mEq of potassium chloride) on the hypertrophic ventricle. Puppies with induced left ventricular hypertrophy were divided into four groups and studied after one hour on global ischemia. Myocardial adenosine triphosphate (ATP) was best preserved in the hypothermically perfused groups and correlated well with measurements of coronary sinus creatine phosphokinase (CPK). In Groups 1 and 2 (anoxic arrest at 37 degrees C and KC1 perfusion at 37 degrees C), CPK at 30 minutes of reperfusion was 1,031 and 198 IU, respectively, compared to 35 IU in Group 3 (KC1 perfusion at 4 degrees C) and 44 IU in Group 4 (Ringer's lactate at 4 degrees C). Myocardial injury was milder in Groups 3 and 4 regardless of whether potassium chloride was added. It is apparent that hypothermic perfusion of a hypertrophic ventricle was the major factor in myocardial preservation, as determined by myocardial ATP and coronary sinus CPK.
 ...
PMID:Advantages of potassium cardioplegia and perfusion hypothermia in left ventricular hypertrophy. 14 17

Sixty-two autopsied hearts, with left ventricular hypertrophy (LVH) caused by mitral regurgitation (MR), aortic failure (AR), combined valvular disease (CVD), hypertension (HHD), or ischemia (IHD), and 23 control hearts with normal left ventricles were studied morphologically for analysis of modes of hypertrophy and for ECG-pathology correlation. Basic disorders modify the mode of hypertrophy; that is, elongated AR-type LV makes muscle fiber orientation in the outer layer more vertical, and globular MR-type LV makes it more horizontal than normal. High-voltage QRS correlates with hypertrophy of the outer layer which is often associated with that of the inner layer. ST depression and T changes correspond to relative deterioration of the inner and median layers, respectively.
 ...
PMID:Histopathological study of hypertrophied myocardium of known etiologies with special reference to correlation of ECG changes. 14 36

Regional myocardial blood flow during both control conditions and ischemia-induced vasodilatation was studied in eight chronically instrumented awake dogs. Seven of these animals had coarctation-banding of the ascending aorta performed at 6 wk of age, and the other dog had congenital subvalvular aortic stenosis. The mean left ventricular weight for the group was 157+/-7.6 g, and the left ventricular body weight ratio was 8.76+/-0.47 g/kg. None of the animals exhibited signs of congestive heart failure. During the control state, the mean left ventricular systolic pressure was 249+/-12 mm Hg and the left ventricular end-diastolic pressure was 11.5+/-0.5 mm Hg. The aortic diastolic pressure was 74+/-6 mm Hg. Mean left circumflex coronary artery blood flow was 71+/-6 cm(3)/min. In the animals with coarctation-banding, 52+/-6% of the flow occurred during systole. In the dog with congenital subvalvular aortic stenosis, 5% of the coronary flow was systolic. Mean transmural blood flow during resting conditions was 0.97+/-0.08 cm(3)/min per g, and the ratio of endocardial to epicardial flow (endo/epi) was 0.88+/-0.07. During reactive hyperemia, the mean transmural blood flow increased to 3.5+/-0.30 cm(3)/min per g; however, the endo/epi decreased to 0.52+/-0.06.THESE STUDIES DOCUMENT A DIFFERENCE IN TRANSMURAL BLOOD FLOW DISTRIBUTION BETWEEN THE NORMAL AND THE HYPERTROPHIED LEFT VENTRICLE: during resting conditions, in the normal ventricle, the highest flow occurs in the endocardial layer, whereas in the hypertrophied ventricle, the highest flow is in the middle layers with the endocardial flow less than the epicardial flow. During ischemia-induced vasodilatation, the abnormal endo/epi becomes accentuated markedly. These data demonstrate that, in situations requiring high flow, the endocardial layer of a heart with marked concentric left ventricular hypertrophy may not be perfused adequately.
 ...
PMID:Myocardial blood flow distribution in concentric left ventricular hypertrophy. 14

Using experimental models of various disease states, the ability of the isolated perfused working rat heart to withstand and recover from a period of severe ischemia was investigated. The results revealed that the coexistence of a diabetic state, obesity, or left ventricular hypertrophy increased the susceptibility of the hearts to ischemic damage and reduced the rate or the extent of postischemic recovery. In contrast, hearts obtained from moderately hypertensive rats exhibited a greater resistance to, and a superior recovery from, ischemia than did hearts obtained from normotensive controls.
 ...
PMID:Myocardial susceptibility to ischemic damage: a comparative study of disease models in the rat. 15 26

To assess the potential benefit of pulsatile perfusion inthe hypertrophied heart during fibrillation, 10 dogs with left ventricular hypertrophy, produced by previous supravalvular aortic banding, were used to compare linear and pulsatile perfusion in the fibrillating heart during total cardiopulmonary bypass. The mass spectrometer was used to measure subendocardial PCO2 and PO2 (PmCO2 and PmO2), and radioactive microspheres were utilized to measure myocardial blood flow in the same layers. Pulsatile perfusion was established using the recently develop "bubble tubing," which produces a pulse pressure of at least 20 mm Hg and can be used in a standard roller-pump apparatus. Both linear and pulsatile flows were compared at mean aortic root pressures of 80 and 50 mm Hg, and these four combinations of aortic root pressure and type of flow were employed for periods of 30 minutes each. Myocardial ischemia developed during linear coronary perfusion at 50 mm Hg, as evidenced by an elevation of PmCO2. Ischemia was not evident during pulsatile perfusion at the same mean pressure. Reversal ischemia was a result of increased myocardial blood flow and pulsatile perfusion, and this increase was shown to occur maximally in the deeper subendocardial layer. Ischemia was not eviden during linear or pulsatile perfusion at an mean perfusion pressure 80 mm Hg. Thus, if lower perfusion pressures are to be tolerated in patients with left ventricular hypertrophy, pulsatile perfusion with the bubble tubing technique may prevent the development of subendocardial ischemia or infarction.
 ...
PMID:Beneficial effects of pulsatile perfusion in the hypertrophied ventricle during ventricular fibrillation. 15 96

Left ventricular hypertrophy was created in 15 pigs by banding the ascending aorta when they were young. The adult animals were placed on normothermic cardiopulmonary bypass and perfused with either nonpulsatile (two groups of pigs) or pulsatile (one group) flows. As long as the perfusion rate was maintained at 70 ml/kg/min, myocardial blood flow distribution as determined by radioactive microspheres, was identical in the hearts with normal sinus rhythm and those with ventricular fibrillation irrespective of the type of perfusion. At low flow rates, however, subendocardial ischemia developed in all three groups, but was most severe in the fibrillating hearts, and was not reversed by pulsatile perfusion.
 ...
PMID:Pulsatile perfusion: its effects on blood flow distribution in hypertrophied hearts. 15 26

Fibromuscular dysplasia of renal arteries was the cause of hypertension in four consecutive children with renal artery stenosis. Two were asymptomatic, the third had had hypertension for seven years but had not been treated, and the fourth, a 9-month-old infant, presented with cardiac failure. Heart enlargement and left ventricular hypertrophy were present in all. Rapid sequence urograms demonstrated a smaller kidney and delayed appearance and disappearance of the contrast medium on the affected side in all. Angiograms showed left RAS in all. Peripheral plasma renin activity was elevated in only three of the four patients. Antihypertensive and diuretic drugs were not very effective therapeutically. Ischemia of the ipsilateral kidney probably prevented normal growth and led to shrinkage of the kidney in one patient. Following nephrectomy the BP has remained normal without any therapy for 24 to 64 months. With normalization of BP, accelerated growth ensued, the cardiomegaly regressed and the hypertensive retinopathy resolved. These patients demonstrate that: (1) FMD is an important cause of RAS. (2) the well-known radiologic feature of FMD, the beaded appearance, is usually not seen in children. (3) control of BP leads to normalization of linear growth, usually impaired in severe hypertension, and (4) target organ complications such as cardiomegaly, LVH, and hypertensive retinopathy are reversible in one to 10 months.
 ...
PMID:Fibromuscular dysplasia of renal arteries: an important cause of renovascular hypertension in children. 15 54

Sixty-five patients were studied with stress electrocardiography and thallium-20 1 relative myocardial perfusion scintigraphy. Results were correlated with selective coronary angiography. Scintigraphy was more sensitive (85 versus 67 percent), more specific (89 versus 63 percent) and significantly more accurate (87 versus 65 percent) than stress electrocardiography for the diagnosis of significant coronary arterial lesions in patients with isoelectric S-T segments at rest. Stress scintigraphy helped clarify the equivocal stress test due to left bundle branch block, left ventricular hypertrophy, drugs, hyperventilation and other conditions and was more accurate than the stress electrocardiogram (89 versus 53 percent) even in the presence of a depressed S-t segment at rest. Thallium-20 1 scintigraphy is a safe and simple noninvasive method for identifying abnormal myocardial perfusion, stress-induced ischemia and, indirectly, significant coronary arterial lesions.
 ...
PMID:Thallium-20 1 myocardial perfusion scintigraphy for the clinical clarification of normal, abnormal and equivocal electrocardiographic stress tests. 62 4

A proposed mechanism for explaining the electrocardiographic response in left ventricular hypertrophy and in subendocardial and epicardial acute ischemia was incorporated in a mathematical model of electrical heart activity. The model of hypertrophy was simply an increase in cell size, and the principal effect on the computer-generated 12-lead electrocardiograms (ECGs) was an increase in R-wave amplitude and ventricular activation time and a flattening or polarity reversal of the T wave. The model of acute ischemia was a reduction between plateau and resting potential of the transmembrane action potential. The principal effect on the computer-generated 12-lead ECGs was an S-T segment displacement up or down depending on the location of the lesion. This shift was linearly proportional to the severity of the ischemia, i.e., the reduction in electrical activity of the ischemic cell, and for a lesion of given severity the S-T segment shift was a measure of the area, not the volume, of ischemic tissue. Therefore, this model suggests that a direct correlation does not necessarily exist between volume-measuring tests such as serum enzyme values in the case of necrosis and S-T segment shifts.
 ...
PMID:A mechanism for the electrocardiogram response to left ventricular hypertrophy and acute ischemia. 111 34

The risk of open heart surgery can be lowered by combination of different methods of myocardial protection. 1. Cardioplegia with a potassium free Mg-1-aspartate and Procaine-solution (Cardioplegin). 2. Coronary perfusion after ischemia longer than 35-40 minutes in case of excessive left ventricular hypertrophy or failure. 3. Hypothermia. Surface cooling gives an additional safety if coronary perfusion is not ideal possible in case of multiple coronary stenoses. For patients with this dispositions a continuous coronary perfusion with cardioplegic solution might be advisable, as it was presented by Gercken in his paper. This method was used three times already in human, but is still in an experimental stage.
 ...
PMID:Induced ischemic cardiac arrest. Clinical and experimental results with magnesium-aspartate-procaine solution (Cardioplegin). 119 31


1 2 3 4 5 6 7 8 9 10 Next >>