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

To assess the prevalence of right ventricular perfusion defects after a recent inferior wall myocardial infarction, 33 patients were studied 6 to 14 days after infarction with low-level exercise testing and technetium 99m (99mTc) sestamibi (SPECT) imaging. Twenty-two control subjects with a < 5% likelihood of coronary artery disease undergoing exercise 99mTc sestamibi imaging were also studied. For each image the right ventricle was computer isolated from reconstructed transverse cardiac slices, followed by reorientation into oblique slices. Both right and left ventricular images were visually assessed for defects. A quantitative method of defect detection was also applied to the right ventricle. For the right ventricle, 100% of the stress images and 96% of the rest images were adequate for interpretation. Right ventricular stress perfusion defects were identified in 10 (30%) of 33 patients with recent inferior infarction, with 50% completely or partially normalizing on rest images, consistent with ischemia. Of 14 patients with left ventricular inferoseptal defects, eight (57%) had right ventricular defects compared with 2 (11%) of 19 without inferoseptal defects (p < 0.005). We concluded that the right ventricle can be adequately assessed for perfusion defects by means of exercise with 99mTc sestamibi SPECT imaging. Defects of the right ventricle after inferior myocardial infarction occur frequently, and many have evidence of ischemia. Right ventricular perfusion defects are closely associated with left ventricular inferoseptal defects.
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PMID:Prevalence of right ventricular perfusion defects after inferior myocardial infarction assessed by low-level exercise with technetium 99m sestamibi tomographic myocardial imaging. 815 17

Postoperative conduction disturbances after coronary artery bypass grafting were analyzed in 100 patients who randomly received either blood or crystalloid cardioplegia. Conduction disturbances, mostly transient, developed after termination of cardiopulmonary bypass in 30 of the 100 patients--15 in either group. Ischaemia appeared to be a major determinant for conduction disturbances. Previous inferior myocardial infarction and stenosis of the right coronary artery both exposed the patient to risk of right bundle branch block.
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PMID:Conduction disturbances after blood and crystalloid cardioplegia in coronary bypass surgery. 819 29

Right ventricular (RV) ischemia occurs in 50% of patients with acute inferior myocardial infarction, and may result in severe hemodynamic compromise associated with poor clinical outcome. Acute right coronary artery (RCA) occlusion proximal to the RV branches results in right ventricular free wall (RVFW) dysfunction. The ischemic, dyskinetic RVFW exerts mechanically disadvantageous effects on biventricular performance. Depressed RV systolic function leads to a decrease in transpulmonary delivery of left ventricular (LV) preload, resulting in diminished cardiac output. The ischemic right ventricle is stiff, dilated, and volume dependent, resulting in pandiastolic RV dysfunction and septally-mediated alterations in LV compliance, which are exacerbated by elevated intrapericardial pressure. Under these conditions, RV pressure generation and output are dependent on LV-septal contractile contributions, governed by both primary septal contraction and paradoxical septal motion. When the culprit coronary lesion is distal to the right atrial (RA) branches, augmented RA contractility enhances RV performance and optimizes cardiac output. Conversely, more proximal occlusions result in ischemic depression of RA contractility, which impairs RV filling, thereby resulting in further depression of RV performance and more severe hemodynamic compromise. Bradyarrhythmias limit the output generated by the rate-dependent noncompliant ventricles. Patients with right ventricular infarction and hemodynamic compromise often respond to volume resuscitation and restoration of a physiological rhythm. Vasodilators and diuretics should generally be avoided. In some, parenteral inotropic stimulation may be required. The right ventricle appears to be relatively resistant to infarction and has a remarkable ability to recover even after prolonged occlusion. Therefore, the term RV infarction appears to be somewhat of a misnomer, for in most patients a substantial proportion of acute RV dysfunction represents ischemic but viable myocardium. Although RV performance improves spontaneously even in the absence of reperfusion, recovery of function may be slow and associated with high in-hospital mortality. Reperfusion enhances the recovery of RV performance and improves the clinical course and survival of patients with ischemic RV dysfunction.
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PMID:Right heart ischemia: pathophysiology, natural history, and clinical management. 944 58

To detect a significant narrowing of the left anterior descending artery in patients with inferior/posterior myocardial infarction, 200 patients underwent standard exercise testing. Age, gender, and grade of stenosis of the left anterior descending artery were similar in 138 patients with inferior myocardial infarction and 62 with posterior myocardial infarction. In patients with left anterior descending artery stenosis, there were more lateral leads with ST-segment depression (1.8+/-1.0 vs 1.1+/-1.1; p<0.01) and fewer anterior leads with ST-segment depression (2.1+/-1.4 vs 2.9+/-1.4; p=0.02) in those with inferior myocardial infarction than in those with posterior myocardial infarction. Applying the criterion of exercise-induced ST-segment depression > or = 0.1 mV, sensitivities and specificities in detecting left anterior descending artery stenosis were 98% and 21% respectively in inferior myocardial infarction and 94% and 26% respectively in posterior myocardial infarction. In contrast, discriminant analysis revealed sensitivities and specificities of 77% and 91% respectively in inferior myocardial infarction and 71% and 81% respectively in posterior myocardial infarction using the variables related to severity of inducible ischemia and lateral and anterior lead ST-segment depression. These results indicate that a multivariate approach underscoring the site of myocardial infarction can help in identifying stenosis of the left anterior descending artery in patients with inferior/posterior myocardial infarction.
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PMID:Diagnostic approach in exercise testing to detect a significant narrowing of the left anterior descending coronary artery in inferior vs posterior myocardial infarction. 958 57

Right ventricular (RV) ischemia occurs in 50% of patients with acute inferior myocardial infarction, and may result in severe hemodynamic compromise associated with poor clinical outcome. Right coronary artery occlusion proximal to the RV branches results in RV systolic dysfunction, which decreases transpulmonary delivery of left ventricular (LV) preload and diminishes cardiac output. The ischemic right ventricle is stiff, dilated, and volume dependent, resulting in pandiastolic RV dysfunction. Under these conditions, RV pressure generation and output depend on LV-septal contractile contributions. When the culprit coronary lesion is distal to the right atrial (RA) branches, augmented RA contractility enhances RV performance and optimizes cardiac output. Conversely, more proximal occlusions result in ischemic depression of RA contractility, which impairs RV filling and performance, leading to more severe hemodynamic compromise. Bradyarrhythmias limit the output generated by the rate-dependent noncompliant ventricles. Patients with RV ischemia and hemodynamic compromise often respond to volume resuscitation and restoration of a physiologic rhythm. In some patients, parenteral inotropic stimulation may be required. The ischemic right ventricle appears to be relatively resistant to infarction and has a remarkable ability to recover. The term RV infarction appears to be a misnomer, as RV performance improves spontaneously even in the absence of reperfusion. Reperfusion, however, enhances the recovery of RV performance and improves the clinical course.
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PMID:Pathophysiology and clinical management of right heart ischemia. 1044 14

Right ventricular (RV) ischemia occurs in a substantial proportion of patients with acute inferior myocardial infarction (MI), and may result in severe hemodynamic compromise. This defines a high-risk subset of patients with a mortality rate of 25% to 30%, as opposed to an overall mortality rate of approximately 6% patients with inferior MI without right ventricular infarction (RVI). Early recognition of RV ischemic dysfunction is of great importance in inferior MI with clinical evidence of low cardiac output, because the therapeutic approaches are very different from that for cardiogenic shock resulting predominantly from severe left ventricular (LV) failure. Management of RV ischemic dysfunction includes maintenance of RV preload with volume loading and maintenance of atrioventricular synchrony, inotropic support, and reduction of RV afterload in the setting of LV dysfunction. Reperfusion therapy should be initiated in patients with RV ischemic dysfunction. Though the RV appears to be relatively resistant to infarction and has a remarkable ability to recover even after prolonged occlusion, successful reperfusion of the right coronary artery and major RV branches rapidly improves RV ejection fraction and hemodynamic status, and decreases in-hospital mortality and morbidity.
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PMID:Right Ventricular Infarction. 1124 56

In a few patients, 12-lead electrocardiograms (ECGs) derived from reduced-lead-set configurations do not match the standard ECG. Constructing an ECG from a reduced number of standard leads should minimize this problem because some of the resultant 12 leads would always include "true" standard leads. The purpose of this study was to compare the ability of a new reduced-lead-set 12-lead ECG ("interpolated" ECG) with the standard ECG to diagnose cardiac arrhythmias and acute myocardial ischemia. The interpolated ECG uses six standard electrode sites (limb leads plus V(1) and V(5)), from which the remaining four precordial leads (V(2), V(3), V(4), and V(6)) are constructed. Standard and interpolated ECGs were compared using data from 2 prospective clinical trials involving 649 patients evaluated for 1) chest pain in the emergency department (ischemia group, n = 509) or 2) tachycardias in the cardiac electrophysiology laboratory (arrhythmia group, n = 140). Diagnoses were identical between standard and interpolated ECGs for bundle branch and fascicular blocks, left atrial enlargement, right ventricular hypertrophy, prior inferior myocardial infarction (MI), and the distinction of ventricular tachycardia from supraventricular tachycardia with aberrant conduction. There was 99% agreement for prior anterior MI (kappa, .935, P =.000). The percent agreement for acute myocardial ischemia on the initial ECG recorded in chest-pain patients in the emergency department was 99.2% (kappa, .978, P =.000). Of the 120 patients who had ST events with continuous standard 12-lead ECG monitoring, 116 (97%) also had criteria for transient ischemia with the interpolated ECG (ie, DeltaST >or= 100 microV in >or=1 lead(s) lasting >or=1 minute(s). The interpolated 12-lead ECG is comparable to the standard ECG for diagnosing multiple cardiac abnormalities, including wide-QRS-complex tachycardias and acute myocardial ischemia. The advantages of this ECG method are that the standard electrode sites are familiar to clinicians and that eight of the 12 leads are "true" standard leads. Hence, QRS-axis and morphology criteria for diagnosing wide-QRS-complex tachycardia and bundle branch and fascicular blocks are preserved.
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PMID:Comparison of a new reduced lead set ECG with the standard ECG for diagnosing cardiac arrhythmias and myocardial ischemia. 1253 95

A patient with DDD pacemaker had pacing dysfunction following an inferior myocardial infarction. The threshold of that implanted right atrial pacing lead was abnormally high but the generator was normal. A temporary lead was inserted into the high right atrium near the appendage and near the low atrium for testing of threshold, which was abnormally high in these 2 places. Forty days after stent implantation in the proximal segment of the right coronary artery, the threshold spontaneously returned to normal. The change threshold of electrode-tissue interface in the right atrium was suspected due to hibernation of right atrium ischemia.
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PMID:Reversible atrial lead dysfunction of DDD pacemaker after recent inferior myocardial infarction--a case report. 1525 92

A 55-year-old man was admitted to our department with a diagnosis of acute inferior myocardial infarction; 1 week later he underwent percutaneous transluminal coronary angioplasty on the proximal right coronary artery; during this procedure, the patient experienced chest pain and his electrocardiogram showed ST-segment elevation in the anterior leads; ventricular fibrillation also occurred. The ST-segment abnormality disappeared within 45 min, and no stenosis or spasm on the left coronary artery were detected during angiographic control; the blood flow in the right coronary artery was normal, but the acute marginal branch was occluded. This is a rare case of right ventricular ischemia caused by occlusion of the acute marginal branch during coronary angioplasty on the right coronary artery.
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PMID:[A case of right ventricular ischemia mimicking acute myocardial infarction during coronary angioplasty on the right coronary artery]. 1746 62

Precise recording of the standard 12-lead electrocardiogram (ECG) is technically time consuming. Placing limb leads on the torso has the major advantages of ease of use, increased speed of application, and decreased artifact. This modified ECG frequently substitutes for the standard 12-lead ECG in intensive care units to detect ischemia, although its implementation should be limited to interpreting arrhythmias. We describe a patient who was misdiagnosed with acute inferior myocardial infarction in a modified 12-lead ECG. To the best of our knowledge, this is the first case report regarding detection of false ST elevations in this setting. Always, a standard 12-lead ECG is recommended to evaluate any ST-T changes.
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PMID:False ST elevation in a modified 12-lead surface electrocardiogram. 1835 46


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