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

To extend the usefulness of multi-lead ambulatory electrocardiography, we attempted to construct body surface isopotential maps of ST segment using our newly designed multi-lead ambulatory electrocardiograph. Material consisted of 40 patients (pts) with angiographically proven coronary arterial stenosis. By a commercially-available 4-channel recorder and a specially designed adapter, 30-lead ECGs were sequentially recorded together with body position signals for 24 hours. Compensation for ST distortion and interpolation of ST level on time scale techniques were performed before construction of ST maps. The extension of ST depression area in pts with single LAD disease were larger than in pts with single LCX or RCA disease. As time elapsed, after occurrence of ischemia the extension and location of ST depression area were changed. These results were thought to be reasonable. In conclusion, the ambulatory recording of body surface ST maps may become useful for study of myocardial ischemia in daily life.
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PMID:[Body surface ST mapping in daily life using multi-lead ambulatory electrocardiograph]. 789 42

Coronary artery endothelium exhibits functional impairment after ischemia and reperfusion. Canine left anterior descending coronary arteries were exposed to ischemia (60 minutes) followed by reperfusion (60 minutes) through a left internal mammary artery graft. In organ chamber experiments, control (left circumflex coronary artery) and reperfused (left anterior descending coronary artery) arterial segments were contracted with prostaglandin F2 alpha and exposed to hypoxia (oxygen tension = 35 +/- 5 mm Hg). Reperfused coronary rings with endothelium exhibited contractions to hypoxia that were significantly greater than contractions in control rings with endothelium (+78% +/- 8% and +14% +/- 5%, respectively; p < 0.05). This phenomenon could be blocked by NG-monomethyl-L-arginine. Electron microscopic studies showed platelet adhesion and aggregation, denudation of the endothelium and disruption of the intercellular junctions, edematous subendothelial matrix, and vesiculation of the smooth muscle cells in reperfused LAD. Swelling, vacuole formation, and loss of neurofilament occurred in the nerve fibers accompanying the vessels. These phenomena were not observed in control vessels. This study demonstrates that early after coronary artery bypass grafting, hypoxia can induce coronary vasospasm mediated by an L-arginine-dependent metabolic pathway in the endothelium. The ultrastructural changes in the coronary endothelium include platelet adhesion, aggregation, and platelet-induced contraction of coronary smooth muscle. The endothelium-dependent hypoxic coronary vasospasm and ultrastructural changes in the coronary endothelium may play an important role in the pathogenesis of myocardial ischemia and infarction after coronary artery bypass grafting.
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PMID:Acute endothelial reperfusion injury after coronary artery bypass grafting. 794 3

We examined whether opening of the ATP-sensitive potassium (KATP) channels in the ischemic myocardium plays an important cardioprotective role during ischemia. Dogs were anesthetized with sodium pentobarbital (30 mg/kg, i.v.). Sixty minutes after treatment of the dog with glibenclamide (0.3 or 3 mg/kg, i.v.), the LAD was ligated. At 3 or 15 min after LAD ligation, left ventricular tissue was taken from the ischemic region to measure tissue metabolite levels. After ischemia, the tissue levels of ATP and creatine phosphate decreased to 49-74% and 26-34%, respectively, and lactate level increased to 380-660%. Ischemia (either 3 or 15 min) increased the levels of G6P and F6P and decreased the FDP level, indicating the inhibition of glycolysis. Glibenclamide at either dose decreased the level of blood glucose by 20-30% and increased the blood insulin level twice. The decrease in ATP and increase in lactate due to ischemia were significantly enhanced by glibenclamide at a dose of 3 mg/kg. The increase in G6P due to 15 min of ischemia were also enhanced significantly by 0.3 and 3 mg/kg of glibenclamide. Glibenclamide worsened the metabolic alterations produced by ischemia. These results suggest that KATP channels that can be inhibited by glibenclamide may perform some functions in the ischemic myocardium.
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PMID:Enhancement of ischemic myocardial metabolic derangement by glibenclamide. 796 25

Twenty years after its first introduction by A. Carpentier, the use of the radial artery (RA) for coronary bypass was reinvestigated because of unexpected good long term results in some patients. Since July 1989, 158 patients (pts) underwent myocardial revascularization using 189 RA grafts (31 pts received 2 grafts). The left internal mammary artery (LIMA) was concomitantly used as a pedicled graft in 151 cases and the right internal mammary artery (RIMA) in 31 cases, a free IMA graft was used in 29 cases and a saphenous vein graft in 40 cases. A mean of 2.8 graft/pt was performed. The target artery receiving the RA was: circumflex (n = 93), diagonal (n = 39), right coronary (n = 47) and LAD (n = 10). Two patients died (1.3%) and three presented a perioperative myocardial infarct (2.5%). Sternal wound infection was noted in three cases of double IMA implant. No ischemia of the hand was observed. All patients received diltiazem started intraoperatively and continued after discharge. In addition, aspirin (100 mg/day) was given at discharge. Early angiographic controls (< 3 weeks) were obtained in the first 60 consecutive patients and revealed: 73/73 patent RA grafts, 58/58 patent LIMA grafts, 16/16 patent RIMA grafts, 15/19 patent free IMA grafts and 10/11 patent vein grafts. Six patients presented a localized narrowing of the RA conduit unrelated to the anastomotic lines (spasm). Late angiographic control (6 to 24 months) was obtained after a mean follow-up of 11 months in 37 patients: 42/46 RA grafts were patent (91.3%) and free of spasm and 4 were occluded.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Use of the radial artery for coronary artery bypass. A new experience after 20 years]. 802 69

Randomized studies have shown that coronary bypass-surgery is effective in prolonging survival and reducing symptoms in various groups of patients with coronary artery disease, when compared with medical therapy alone. This effect is most pronounced and stable in patients who received an internal-mammary-artery graft. Therefore internal-mammary-artery grafting for lesions of the left anterior descending coronary artery is preferable whenever indicated and technically feasible. While percutaneous transluminal coronary angioplasty is effective in improving symptoms of angina pectoris, beneficial effects on survival have not yet been shown. In randomized trials of PTCA versus bypass-surgery acute results were comparable. During follow-up significantly less re-interventions and more angina-free patients were seen in the bypass-groups, indicating a more stable result after bypass surgery. In older patients with a higher mortality and rate of cerebral vascular events during surgery, a palliative PTCA of the culprit lesion may be superior to the bypass-operation. For the often used "unproven" indications for PTCA (silent ischemia, infarct-related artery in asymptomatic patients, isolated proximal LAD-stenosis, acute myocardial infarction, cardiogenic shock) larger randomized trials should be awaited to prove the effectiveness of PTCA in these settings.
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PMID:[Ischemia--reliable results of therapy, operation and angioplasty--in coronary disease]. 815 67

The efficacy of the transfemoral left-ventricular assist device Hemopump (HP; 21 Fr outer diameter) was examined in experiments with adult sheep in two different models of cardiogenic shock (tachycardia shock; ischemia shock), and during ventricular fibrillation. During tachycardia (high frequency pacing-induced; n = 14), HP assist led to a significant increase in cardiac output (from 2.2 to 2.8 liters/min), mean aortic pressure (from 47.6 to 65.6 mmHg), and myocardial perfusion pressure (from 25.5 to 59.0 mmHg). Simultaneously, a normalization of body oxygen-uptake (from 1.4 to 2.5 ml/min.kg), a decrease in myocardial oxygen consumption (from 6.1 to 4.8 ml/min.100 g), and a normalization of myocardial lactate metabolism were observed during HP assist. During regional myocardial ischemia (PTCA balloon occlusion of the proximal LAD (3.5 min; n = 12), HP assist led to significant decrease in LV end-diastolic pressure (from 21.1 to 12.1 mmHg), and increase in diastolic aortic pressure (from 58 to 67 mmHg) resulting in significant increase in coronary perfusion pressure. In the early reperfusion period, myocardial release of both lactate and potassium was significantly lowered with HP assist. During ventricular fibrillation (induced by electrical stimulation; n = 9), HP flow rates decreased from 2.5 (after 10 min) to 2.1 liters/min (after 30 min). Mean aortic pressures simultaneously decreased from 64.0 to 54.6 mmHg. Perfusion conditions were sufficient for maintenance of aerobic myocardial metabolism, but were borderline for peripheral circulation. Our hemodynamic and metabolic data demonstrate beneficial effects of cardiac assist with the Hemopump 21 Fr in both tachycardia-induced severe cardiogenic shock and during acute regional myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Left-ventricular unloading by transvalvular axial flow pumping in experimental cardiogenic shock and during regional myocardial ischemia. 820 70

Previous studies have shown a close temporal relationship between lipid abnormalities and membrane dysfunction in ischemia and that phospholipase-inhibiting drugs limit such derangements. Amiodarone is a potent phospholipase inhibitor, but its potential or that of any other inhibitor to simultaneously attenuate lipid abnormalities and electrophysiological changes in the very early phase of ischemia has never been studied. We therefore investigated simultaneously such changes in early ischemia. In isolated porcine hearts perfused with or without pure amiodarone solutions, electrophysiologic changes before and during 20 min of LAD occlusion were recorded using unipolar electrodes and Franz contact electrode catheters, and full thickness myocardial biopsies obtained for lipid analyses. In untreated hearts (n = 5), occlusion of LAD resulted in the rapid onset of TQ depression/ST elevation within 1 min and plateauing at 10 min. There were mean increases of 33% and 50% in lysophosphatidylcholine and 33% and 70% in lysophosphatidylethanolamine levels at 5-7 min and 20 min of ischemia, respectively. Non-esterified fatty acid (NEFA) content did not change significantly during the first 5-7 min, but increased by 75% after 20 min of LAD occlusion. In treated hearts (n = 5) there was a 37% increase in sinus cycle length after amiodarone administration (503 +/- 85 vs 689 +/- 115 ms, P < 0.01) but no significant change in ventricular effective refractory period (202 +/- 22 vs 204 +/- 21 ms), action potential duration (215 +/- 11 vs 217 +/- 7 ms), or amplitude (31 +/- 6 vs 28 +/- 3 mV) was observed. Also, amiodarone treatment did not alter total phospholipid content, lysophospholipids and NEFA levels of non-ischemic hearts. However, there was significant attenuation (P < 0.01) of the onset of the TQ/ST shift and preservation of action potential amplitude (P < 0.02) during the first 5-7 min of LAD occlusion with concomitant suppression of the increase in both lysophospholipids (hydrolysis products of membrane phospholipids by endogenous phospholipases) and NEFA levels observed after 5-7 and 20 min of ischemia. The results suggest that amiodarone can delay the onset and limit the extent of electrophysiologic change in early myocardial ischemia in temporal association with suppression of myocardial phospholipase activities.
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PMID:Phospholipase inhibition and the electrophysiology of acute ischemia: studies with amiodarone. 828 71

Although calcium channel blockers may preserve function in ischemic myocardium, they may also produce myocardial depression and dysfunction in the presence of decreased coronary flow. This study was designed to examine the issue of possible protection afforded by diltiazem against ischemia-induced myocardial dysfunction during propofol anesthesia. In eight anesthetized and ventilated dogs, regional myocardial (ultrasonic crystals in both left anterior descending [LAD] and left circumflex [LC] perfusion areas) and global ventricular function were evaluated during progressively severe degrees of myocardial ischemia (LAD constriction) before and after intravenous diltiazem (150 micrograms/kg). As coronary flow decreased, heart rate increased, and arterial and coronary perfusion pressures, left ventricular dP/dt, and cardiac output decreased. Systemic vascular resistance was unaffected. Diltiazem without coronary constriction increased heart rate, and decreased diastolic arterial pressures, left ventricular (LV) end-diastolic, coronary perfusion pressures, LV dP/dt max, LAD coronary blood flow, stroke volume, and cardiac output. At all levels of coronary constriction following diltiazem, there were decreases in systolic and diastolic arterial pressures, stroke volume, cardiac output, LV dP/dt, and coronary perfusion pressure. Heart rate increased at critical coronary constriction, and then remained constant relative to the prediltiazem state. The regional muscle effects of the reductions in coronary flow in the LAD perfusion territory included decreased systolic shortening and increased postsystolic shortening before and after diltiazem. Diltiazem did not alter the magnitude of the alterations in systolic or postsystolic shortening brought about by coronary constriction. No changes occurred in the LC area.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Diltiazem and regional left ventricular function during graded coronary constriction and propofol anesthesia in the dog. 830 61

The present study was undertaken to evaluate the improved protection of antegrade aortic root perfusion combined with intermittent coronary sinus occlusion (APCSO) for the 1-hour ischemic myocardium in the presence of left anterior descending artery occlusion, 12 dogs were divided into 2 groups: anteperfusion (AP) alone (n = 6) and APCSO (n = 6). The experimental results showed that APCSO provided a better cardioplegic distribution and a lower hypothermia (15.6 degrees C versus 17.2 degrees C) in the occluded LAD region, compared with AP. After ischemia, cardiac index and left ventricular stroke index recovered excellently in APCSO (128% to 141% and 115% to 158% of preischemic values, respectively), and much worse in AP (69% to 82% and 53% to 73% of preischemic values, respectively). Our study has confirmed that APCSO is superior to AP in myocardial protection in the presence of coronary artery occlusion.
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PMID:Improved myocardial protection by antegrade perfusion in combination with coronary sinus occlusion in the presence of left anterior descending artery obstruction. 832 29

The susceptibility to ventricular arrhythmias under the conditions of cardiac ischemia and reperfusion was investigated in the Langendorff heart preparation of rats fed for eight weeks a standard chow enriched with 2% of pulverized wild garlic leaves. The isolated hearts were perfused with a modified Krebs-Henseleit solution. The incidence of ventricular fibrillation (VF) during 20 min occlusion of the descending branch of the left coronary artery (LAD) was significantly reduced in the wild garlic group as compared to untreated controls (20% vs 88%). The same holds for the size of the ischemic zone (33.6% vs 40.9% of heart weight). In the reperfusion experiments (5 min after 10 min ischemia), ventricular tachycardia (VT) occurred in 70% of the wild garlic group vs 100% in untreated controls and VF in 50% vs 90%. The time until occurrence of extrasystoles, VT or VR was prolonged. No significant alterations in cardiac fatty acid composition could be observed. Although the prostacyclin production was slightly increased in hearts of the wild garlic group, inhibition of cyclooxygenase by acetylsalicylic acid (ASA; aspirin) could not completely prevent the cardioprotective effects suggesting that the prostaglandin system does not play a decisive role in the cardioprotective action of wild garlic. Furthermore, a moderate angiotensin converting enzyme (ACE) inhibiting action of wild garlic was found in vitro as well as in vivo that could contribute to the cardioprotective and blood pressure lowering action of wild garlic. Whether a free radical scavenging activity of wild garlic is involved in its cardioprotective effects remains to be established.
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PMID:Cardioprotective actions of wild garlic (allium ursinum) in ischemia and reperfusion. 845 76


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