Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

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

We tested the hypothesis that impaired and incomplete relaxation of the strong twitch of mechanical alternans causes the peak force deficit (PFD) of the weak twitch and that, by decreasing the relaxation deficit (RD) of the strong twitch, dobutamine would diminish the PFD. We studied isometric twitches of the in situ blood-perfused canine papillary muscle (n = 8). To produce mechanical alternans, we paced the heart at 110-155 beats/min and decreased mean coronary perfusion pressure (MCPP) stepwise to produce ischemia and then increased it to produce reperfusion. We measured the RD and PFD and fit each curve of isometric force [F(t)] with the relation F(t) = F0 + C(t/A)Be1-(t/A)B, where F0 is force at twitch onset, to obtain the parameters A, B, and C. B is a dimensionless index of myocardial relaxation; it decreases with impaired (delayed) relaxation. At each MCPP, we averaged B for the strong and weak twitches. The PFD showed a positive correlation with the RD. At each MCPP, mean B was lower for the strong twitch than for the weak twitch, indicating impaired relaxation of the strong twitch. Dobutamine increased B from 1.83 +/- 0.14 to 2.12 +/- 0.16 (P = 0.00002) in the strong twitch and decreased B from 4.15 +/- 2.42 to 2.19 +/- 0.18 (P = 0.05) in the weak twitch. Dobutamine thus equalized the relaxation of the strong and weak twitches. Consequently it decreased the RD from 2.57 +/- 2.14 to 0.16 +/- 0.24 g (P = 0.01) and the PFD from 5.50 +/- 3.67 to 1.04 +/- 1.15 g (P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Mechanism of mechanical alternans in ischemia-reperfusion: role of deficient relaxation of the strong twitch. 763 46

The cardiovascular evaluation of patients with end-stage renal disease (ESRD) has been hampered by the suboptimal sensitivity and specificity of currently employed diagnostic tests. Dobutamine stress echocardiography (DSE) is a recently developed technique which is accurate for the diagnosis of coronary artery disease (CAD) in general populations. The purpose of this study was to assess its diagnostic accuracy and prognostic implications in patients with ESRD. Patients with ESRD (n = 97) underwent DSE as part of a preoperative evaluation before being listed for renal transplantation. Patients were followed for 12 +/- 6 months (range 1 to 24) after the study. Rest and dobutamine stress echocardiograms were analyzed for regional and global function. Coronary angiography was performed in 30 patients, and 25 underwent renal transplantation in the follow-up period. DSE had a sensitivity of 95% (92% for 1-vessel, 100% for > or = 2-vessel disease), specificity of 86%, and accuracy of 90% for the detection of CAD. During the follow-up period, 6 patients died; DSE revealed inducible ischemia in 4, and catheterization before death revealed multivessel CAD in 2. Conversely, a normal DSE identified a very low risk population, with a 97% probability of being free of cardiac complications or death during the follow-up period. We conclude that DSE accurately identifies CAD in patients with ESRD and identifies a cohort of patients at low risk for cardiac complications.
...
PMID:Usefulness of dobutamine stress echocardiography in detecting coronary artery disease in end-stage renal disease. 790 Jun 65

Dobutamine stress echocardiography has increasingly been used to assess patients for coronary artery disease. Despite the popularity of this test, the optimal dose of dobutamine has not been established. The objective of this study was to assess the accuracy of dobutamine stress echocardiography at various infusion doses and its utility as a predictor of perioperative risk in patients undergoing a noncardiac surgical procedure. One hundred thirteen consecutive patients underwent dobutamine stress echocardiography, subsequent cardiac catheterization and/or a noncardiac surgical procedure. Three patient groups were analyzed on the basis of peak dobutamine infusion rates (17 +/- 4, 29 +/- 2, and 40 +/- 0 micrograms/kg/min, respectively). The three groups were comparable with regard to age, sex, ejection fraction, and severity of coronary artery disease. In group I, the sensitivity and specificity of dobutamine stress echocardiography were 74% and 33%, respectively, with a positive predictive value of 78%. In group II, the sensitivity and specificity improved to 84% and 78%, with a positive predictive value of 89%. In group III, the sensitivity and specificity were 86% and 80%, respectively, with a positive predictive value of 86%. In the noncardiac surgical group there was only one nonfatal cardiac complication among the 50 patients with a dobutamine echocardiogram, which was negative for evidence of inducible ischemia. In conclusion, this study demonstrates that dobutamine stress echocardiography should use an infusion rate of > or = 30 micrograms/kg/min to optimize diagnostic accuracy relative to angiographic coronary artery disease. A test that shows no evidence of new, inducible ischemia predicts a low risk of perioperative cardiac events in patients undergoing noncardiac surgery, even at an infusion rate as low as 20 microns/kg/min.
...
PMID:Dobutamine stress echocardiography: clinical utility and predictive value at various infusion rates. 794 51

Nuclear cardiology techniques may be of help in evaluating the patient with symptoms of congestive heart failure and ventricular dysfunction in two respects: quantification of functional parameters by radionuclide angiography, and differentiation of viable from nonviable myocardium by perfusion and metabolic imaging. Left ventricular ejection fraction and volumes can be accurately assessed by equilibrium radionuclide angiography with a count-based method without any geometric assumptions. Indeed, because of its high reproducibility, this method is particularly suited for making sequential measurements in the same patient. The distinction between viable or reversible and scarred or irreversible dysfunctional myocardium can be made on the basis of myocardial perfusion, cell membrane integrity, and metabolic activity. Thallium myocardial imaging is used clinically to assess the first two parameters based on experimental data. Two clinical methods may be applied to the detection of viability: stress-redistribution-reinjection imaging or rest-redistribution imaging. In both of these, the severity of the reduction in thallium activity should be assessed to discriminate viable from nonviable myocardium. Stress-redistribution-reinjection thallium imaging should be the first approach, if possible, because inducible ischemia is a much more significant clinical variable in a patient with ventricular dysfunction in terms of management and risk assessment than is knowledge of myocardial viability. Positron emission tomography (PET) provides enhanced image resolution and correction for body attenuation, thereby overcoming the two major limitations of thallium imaging. In addition, it provides the capacity to quantitate regional blood flow and to assess regional metabolic activity independent of flow. Overall, the accuracies of thallium imaging (around 70%) and PET imaging (around 82%) are similar for the prediction of segmental changes after revascularization. However, in patients with poor global left ventricular function, the accuracy of PET seems to be better. Further studies are needed in a large number of patients evaluated for regional and global function to establish algorithms using thallium and PET imaging in dysfunctional myocardium. Dobutamine echocardiography should also be evaluated in these algorithms.
...
PMID:Assessment of left ventricular dysfunction by nuclear cardiology. 794 81

This study describes the results of Dobutamine stress echocardiography in 10 patients with Syndrome X. The diagnosis of Syndrome X was made on the basis of the presence of exertional angina, positive exercise stress test, negative ergonovine stress test and normal coronary arteries at angiography. All patients underwent Dobutamine stress echocardiography after interruption of any antianginal therapy. Dobutamine was infused starting with a dose of 5 mcg/kg/min over 3 minutes with incremental steps of 5 mcg/kg/min every 3 minutes up to a maximal dose of 40 mcg/kg/min. Two-dimensional echocardiography and 12-lead electrocardiography was monitored during the infusion of the drug. Nine patients received the maximal dose while one patient prematurely stopped the test for the occurrence of side effects. None of the ten patients developed segmental left ventricular wall motion abnormalities indicative of myocardial ischemia; ST-segment depression diagnostic for ischemia developed in 30% of patients; angina was elicited in one of these patients and in two additional patients. A hyperkinetic response to Dobutamine infusion involving all the segments of the left ventricle was observed both in patients with and without chest pain or electrocardiographic changes. In patients with Syndrome X Dobutamine induces a hyperkinetic left ventricular response indicative of normal contractile reserve despite the presence in some cases of angina and electrocardiographic signs of ischemia.
...
PMID:Results of dobutamine stress echocardiography in patients with syndrome X. 796 53

Intestinal mucosal ischemia is one of the earliest manifestations of impaired core tissue perfusion in critically ill patients. The aim of this study was to investigate the effects of dobutamine and dopamine on intestinal ischemia in ten anesthetized dogs. Intestinal intramural pH (pHi) by tonometry is an early reliable marker of assessing the adequacy of tissue oxygenation. A tonometer was inserted into the midjejunum through enterotomy. The superior mesenteric artery (SMA) blood flow was measured by a transit-time ultrasonic flowmeter. A vascular screw clamp for blood flow reduction was placed at the origin of the SMA, proximal to the flow probe. The SMA blood flow was maintained at 70% of baseline flow for three hours. After two hours of decreased blood flow, intravenous dobutamine or dopamine was infused at a rate of 5 micrograms.kg-1.min-1 for one hour. The pHi fell significantly from 7.16 +/- 0.04 to 7.08 +/- 0.04 in dobutamine group, and from 7.18 +/- 0.04 to 7.06 +/- 0.05 in dopamine group two hours after induction of intestinal ischemia. Treatments with dobutamine and dopamine increased the SMA blood flow to near baseline levels. Dobutamine caused a significant increase in pHi to 7.11 +/- 0.04. On the contrary, dopamine tended to decrease pHi further to 7.01 +/- 0.09. These results suggest that dobutamine may improve intestinal tissue oxygenation. However, dopamine even at lower doses, may induce constriction of the intestinal mucosal arterioles.
...
PMID:[How should we treat intestinal ischemia?--1: Effects of dobutamine and dopamine]. 796 23

Dobutamine stress echocardiography was performed in 24 patients with angiographically defined coronary artery stenosis, before they underwent percutaneous transluminal coronary angioplasty. Ischemia was detected on stress-ECG in 13 patients. In 19 patients ischemia could be detected with dobutamine stress echocardiography. The method was highly sensitive for detecting ischemia in patients with two vessel or three vessel disease and in patients with affection of only the left anterior descending artery. In patients with one vessel disease the method showed low sensitivity. The most common side effects of dobutamine infusion were flushing and palpitations. One patient suffered atrial fibrillation and one patient had a short and self-limiting ventricular tachycardia. The method seems to be a useful and safe supplementary tool for detecting myocardial ischemia. It is also useful for characterizing the physiological effect of coronary artery stenosis.
...
PMID:[Stress echocardiography with dobutamine. A new method for diagnosis of ischemia]. 799 53

The aim of the study was to compare the ability of dobutamine and dipyridamole echocardiography to detect stunned but viable myocardium early after acute myocardial infarction, to predict spontaneous functional recovery of the reperfused myocardium at 2 months and to detect myocardial ischemia in the infarcted area. Within 10 days from acute myocardial infarction, 47 patients, 29 anterior and 18 inferior, 41 Q-wave and 6 non Q-wave infarctions, underwent dobutamine echocardiography test at low-dose (5-10 mcg/kg/min over 5 min) and high-dose (20-40 mgc/kg/min over 3 min) and to dipyridamole echocardiography test (0.56 mg/kg over 4 min + 0.28 mg/kg over 2 min) in different days and in random order, after interruption of any vasoactive drug. Resting echocardiography was repeated at 2 months in 38/47 patients. Regional wall motion analysis was performed in a qualitative manner on a 14-segment model; viability was defined as improvement of 1 grade or more of at least 2 basally asynergic segments in the infarcted area. Ischemia was defined as an improvement followed by significant deterioration of contractility of the infarcted segments or deterioration of the infarcted area. All patients underwent coronary arteriography within 1 month from admission. Viability was detected by low-dose dobutamine in 34/47 patients (72%) and in 131/297 (44%) of basally asynergic segments compared to only 21/47 patients (45%) and in 66/297 segments (22%) detected by dipyridamole; myocardial ischemia was induced by dobutamine in 64% of patients compared to 36% by dipyridamole. Late spontaneous functional recovery was detected in 21/38 patients (57%) and in 70/244 (29%) of asynergic segments. Sensitivity of dobutamine and dipyridamole echocardiography for predicting spontaneous functional recovery was 70% and 46% specificity 69% and 83%, positive predictive value 48% and 52%, negative predictive value 85% and 79% respectively. Dobutamine correctly identified the presence of a significant stenosis of the infarct-related artery in 74% of cases compared with 43% of dipyridamole; specificity for detecting stenosis was 67% for dobutamine and 83% for dipyridamole. In conclusion, in patients with thrombolyzed myocardial infarction dobutamine echocardiography detects viable myocardium with late spontaneous recovery in a greater proportion of patients and segments than dipyridamole; dobutamine has a higher sensitivity but a lower specificity compared to dipyridamole for identifying a residual stenosis of the infarct-related artery that may jeopardize myocardium in the area at risk.
...
PMID:[The echo-dobutamine and echo-dipyridamole tests in assessing vital myocardium and residual ischemia in myocardial infarct after thrombolysis]. 801 19

Atrial pacing and dipyridamole transesophageal echocardiography have been shown to be sensitive and specific tests for the detection of coronary artery disease. However, the sensitivity and specificity of dobutamine transesophageal echocardiography have not been reported. The purpose of this study was to determine the feasibility, sensitivity, and specificity of dobutamine transesophageal echocardiography for the detection of coronary artery disease. Transesophageal echocardiographic assessment of left ventricular function was performed in 81 adult patients aged 62 +/- 12 years during stepwise infusion of dobutamine from 5.0 to 40 micrograms/kg/min. Ischemia was diagnosed by the development of severe hypokinesis, akinesis, or dyskinesis of a previously contractile left ventricular segment. Coronary artery disease was defined by angiography as a reduction in luminal diameter of > or = 70% of an epicardial or > or = 50% of the left main coronary artery. In patients who had undergone coronary artery bypass graft surgery, a stenotic bypass graft was defined as a reduction in luminal diameter of > or = 70%. In patients without previous CABG, significant coronary artery disease was present in 21 patients: 5 with single-vessel disease, 7 double-vessel disease, 8 triple-vessel disease, and 1 left main coronary disease. Dobutamine transesophageal echocardiography had a sensitivity of 90% (19 of 21) and specificity of 94% (49 of 52) for the detection of coronary artery disease. In patients with previous CABG (n = 8), the sensitivity and specificity for the detection of bypass graft stenosis were 100% (4 of 4) and 75% (3 of 4), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Dobutamine two-dimensional transesophageal echocardiographic stress testing for detection of coronary artery disease. 801 82

Dobutamine pharmacologic stress test coupled with dual isotope-stress hexakis 2-methoxy-isobutyl-isonitrile (MIBI), rest Thallium 201-perfusion SPECT was performed to a patient with an end-stage coronary artery disease who has physical limitations and cannot achieve a desired stress level with conventional stress protocols. Although this patient was assessed to be an inoperable case according to coronary angiography or echocardiography data, he was operated on the basis of imaging of a viable myocardium and reversible coronary ischemia to a significant extent in the dobutamine stress coupled with dual isotope study. The objective benefits of the operation was also shown on the postoperative data. We'd like to discuss an alternative diagnostic option contributing more appropriate solutions for patients with an end-stage coronary artery disease.
...
PMID:Decision-making for surgery in patients with end-stage coronary artery disease: the role of dual isotope myocardial perfusion SPECT after dobutamine infusion. 805 86


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

---