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

The study includes 50 patients with severe, stable angina who have undergone the saphenous vein bypass operation. Patients were evaluated preoperatively and postoperatively with regard to exercise tolerance, incidence of stress-induced agina, ST-segment changes of ischemia, and ventricular function as indicated by stroke work index (LVSWI) and ejection fraction. Comparisons were made between patients with complete revascularization (CR) and patients with postoperative residual ischemia (RI). Results revealed that exercise duration improved significantly in both the CR and RI groups. In the CR group, angina and ischemic ST changes were completely eliminated. In the RI group, there was a 25 percent incidence of stress angina and a 50 percent incidence of ischemic ST-segment changes. In neither group was the ejection fraction significantly different from preoperative values. LVSWI decreased significantly in both groups postoperatively.
J Thorac Cardiovasc Surg 1977 Jul
PMID:Evaluation of saphenous vein bypass surgery with multistage treadmill test and ventricular function studies. 30 89

The long-term effectiveness of a retrograde coronary venous bypass graft (CVBG) to an ischemic left ventricle was evaluated in 18 dogs. A saphenous vein was interposed between the aorta and left anterior descending (LAD) vein. The LAD vein was ligated cephalad to the CVBG to prevent an arteriovenous fistula. The LAD artery was ligated at its origin to create anterior wall ischemia. Operative graft flow averaged 53 ml. per minute. The 14 surviving dogs were catheterized 3 to 5 months later. Ten of the 14 CVBG's were patent angiographically. The chests were opened and graft flow now averaged 50 ml. per minute. 141Ce microspheres were injected into the left atrium to measure myocardial flow to the anterior wall. In the 10 dogs with patent grafts, transmural flow was 39 +/- 1 (S.E.M.) ml. per 100 Gm. of tissue per minute. The endocardial/epicardial flow ratio was 1.4/1, indicating that retrograde venous perfusion effectively delivered blood to the subendocardium. After ligation of the CVBG, microsphere measured flow dropped to 15 +/- 1 ml. per 100 Gm. per minute. In 15 control dogs, anterior wall flow was 100 +/- 3 ml. per 100 Gm. per minute, decreasing to 13 +/- 2 ml. 45 minutes after ligation of the LAD artery and vein. None of the eight control dogs with simple ligation of the LAD artery and vein survived more than 5 days. Histologic examination of the anterior wall of the left ventricle, the area served by the CVBG's for 3 to 5 months, disclosed no evidence of venous sclerosis or thrombosis and no evidence of interstitial edema or hemorrhage. Thus a CVBG permitted long-term survival in an otherwise nonviable anatomic preparation. Moreover, restoration of flow with a CVBG was effective because it perfused all layers of the myocardium, especially the subendocardium--the crucial layer of myocardial muscle.
J Thorac Cardiovasc Surg 1979 Jan
PMID:Selective arterialization of the coronary venous system. Encouraging long-term flow evaluation utilizing radioactive microspheres. 30 74

To evaluate the re-establishment of the bronchial circulation in lung transplantation, we studied 10 immunosuppressed dogs up to 14 weeks after left lung allografting. Selective in vivo bronchial arteriograms were performed repetitively via the transfemoral route. In the early postoperative period, no fillinf og vessels distal of the bronchial anastomosis could be shown. After 12 days, however, continuity of the bronchial arteries across the anastomosis was present, and dye-filled ramifications of these vessels were visualized on the secondary and tertiary bronchi. Reconstitution of the bronchial circulation was also confirmed by postmortem studies after injecting the isolated descending thorasis aorta with colored radiopaque material (microfil). The bronchial mucosa at autopsy was examined microscopically. There was no correlation between its viability and bronchial artery regeneration. Although early ischemia of the transplant bronchus may be after a factor in the bronchial complcations that follow lung transplantation, the present study indicates that this ischemia is not due to failure of bronchial artery regeneration.
J Thorac Cardiovasc Surg 1977 May
PMID:Restoration of bronchial artery circulation after canine lung allotransplantation. 32 82

This report describes morphologic observations in autogenous saphenous veins, autogenous internal mammary arteries, radial arteries and arterial heterografts used as aortocoronary bypass conduits. The normal or expected changes and the abnormal or unexpected changes observed in each type of bypass conduit is discussed. The three major changes seen in saphenous vein grafts in the aortocoronary position are: (1) medial fibrous replacement; (2) adventitial fibrous proliferation; and (3) intimal fibrous proliferation. Medial fibrous replacement is the result of vein wall ischemia and necrosis and ultimately replacement of smooth muscle cells; adventitial fibrosis is the result of organization of fibrin and red cell clot and repair of ischemic damage. The cause of intimal fibrous proliferation is unclear but appears to be the result of chronic repair of injured intima and endothelium. That the severity of the changes varies along the length of one graft or among grafts in the same patient suggests that other factors contribute to the development of the changes observed. Although some structural changes have been observed, internal mammary arteries are relatively resistant to the changes seen in saphenous veins. Radial arterial grafts have shown severe structural changes with time, to a degree greater than that seen in the saphenous vein grafts. Heterograft conduits so far have been unsuccessful in the aortocoronary position in humans. The severe changes seen in radial artery and heterograft conduits indicate that they are inadequate for use as substitutes for saphenous vein and mammary artery as bypass conduits from aorta to coronary artery.
Cardiovasc Clin 1977
PMID:Morphologic observations in biologic conduits between aorta and coronary artery. 33 66

Myocardial ischemia causes a series of anatomic and physiologic abnormalities that can be detected and quantified by assessment of myocardial perfusion, mechanical function, electrophysiology, and metabolism. These methods of assessment vary widely in sensitivity, specificity, relevance, cost, and ease of application. Although occasionally the appropriate choice of diagnostic procedures is clinically difficult, the demonstrated potential of coronary artery bypass surgery to reverse both acute and chronic myocardial ischemia makes the detection of ischemia an important effort in the care of patients with coronary artery disease.
Cardiovasc Clin 1977
PMID:Detection of myocardial ischemia. 33 74

The effect of extracellular crystalloid (Ringer's) and colloid (silica gel fraction [SGF]) solutions, and intracellular crystalloid (Sacks) and colloid (modified silica gel fraction [MSGF]) solutions for canine heart preservation in a 24 to 48 hour model of hypothermic storage and zero to 30 minutes of warm ischemia was compared. Canine hearts flushed with an intracellular colloid solution (MSGF) had better survival rates after transplantation than did the hearts flushed with intracellular crystalloid solutions (Sacks). Better survival results also were observed in the group of hearts flushed with extracellular colloid (SGF) solutions than extracellular crystalloid (Ringer's) solutions. The most important theoretical factor in heart preservation appears to be hyperosmolarity and elevated concentration of potassium, proteins, and glucose.
J Thorac Cardiovasc Surg 1977 Oct
PMID:Preservation of canine hearts after warm ischemia (zero to thirty minutes) and one to two days of hypothermic storage. A comparative analysis of crystalloid and colloid solutions with different osmolarity and ion composition. 33 90

Using radioactive microspheres, we studied the quantitative and sequential distribution of myocardial blood flow during acute rejection of cardiac orthotopic allografts in 15 nonimmunosuppressed dogs. During rejection mean cardiac output per kilogram decreased 49 percent from control, stroke volume per kilogram decreased 40 percent, total left ventricular flow decreased 43 percent, and the subendocardial/subepicardial flow ratio (I/O) of the left ventricular free wall decreased 21 percent. Relative subendocardial hypoperfusion occurred despite an increase in the ratio of left ventricle subendocardial supply (diastolic pressure-time index) to demand (tension-time index). The data indicate that total left ventricular flow decreases severely and selective left ventricular subendocardial ischemia develops very early during acute cardiac rejection.
J Thorac Cardiovasc Surg 1978 Apr
PMID:Alterations in total and regional myocardial blood flow during acute rejection of orthotopic canine cardiac allografts. 34 80

Methylprednisolone was given at different intervals before warm ischemia of the heart (37 degrees C. for 60 minutes), and viability of these hearts was evaluated after transplantation into the abdomen of another dog. Animals were divided into four groups: Group 1 received no methylprednisolone: Groups II, III, and IV received 30 mg. of methylprednisolone per kilogram 10 minutes, 60 minutes, and 120 minutes before warm ischemia. In all parameters measured, the animals of Group IV performed better than the other groups. It is concluded that methylprednisolone, when given 2 hours before warm ischemia, exerts a protective effect on the ischemic myocardium.
J Thorac Cardiovasc Surg 1979 Apr
PMID:Myocardial protection with methylprednisolone. Evaluation of viability of hearts subjected to warm ischemia before transplantation. 37 Apr 61

Two cases of atypical localization of an aortic coarctation are described. One patient was a hypertensive girl with a hypoplastic type of coarctation in the descending aorta. After insertion of a bypass graft the hypertension disappeared. The other patient was a hypertensive girl with a total aplasia of the distal abdominal aorta and a hypoplasia of a right renal artery. After right nephrectomy the blood pressure became normal. There were no symptoms or signs of ischemia of the legs. This is the second case, known in literature, with a total aplasia of the abdominal aorta. Some general considerations about atypical coarctations are made.
J Cardiovasc Surg (Torino)
PMID:Uncommon congenital anomalies of the aorta. 42 52

The conducting system was studied in an in situ perfused swine heart preparation with reduced coronary flow (ischemia) using perfusate containing high and low levels of glucose (26.6 versus 8.6mM) with and without insulin. Coronary flow was maintained at normal levels for 60 minutes in control hearts. In ischemic hearts flow was reduced to about 50 percent of control levels for 30 minutes. Ultrastructural studies documented only subtle modifications of Purkinje fibers in ischemic hearts. Glycogen depletion and disruption of cell junctions were observed in some fibers. One consistent finding was the activation of the lysosomal system. The outer membranes of primary lysosomes appeared herniated and in some cases disrupted, and small vesicles containing hydrolytic enzymes were seen in association with the Golgi apparatus and larger primary lysosomes. Specimens prepared for the demonstration of acid phosphatase indicated a redistribution of hydrolytic enzymes in Purkinje fibers with a depostion of acid hydrolases in smaller lysosomal vesicles, the transverse and side-to-side junctions between cells, and occasionally in the sarcoplasmic reticulum. Enriched perfusate containing high levels of glucose with insulin appeared to have no therapeutic effects in terms of the structure of the Purkinje fibers. The results suggest that alterations in the lysosomal system may be one of the earliest structural changes which occur in oxygen-deficient hearts.
J Thorac Cardiovasc Surg 1979 May
PMID:Ischemic injury to the conducting system of the heart. Involvement of myocardial lysosomes. 43 Oct 98


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