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

We have developed an in vivo model for chronic evaluation of prosthetic heart valves using juvenile domestic sheep. This report summarizes the results of a study conducted to assess a new bileaflet prosthetic valve. Nine juvenile sheep underwent mitral valve replacement using standard cardiopulmonary bypass techniques including mild hemodilution, systemic hypothermia, and cold fibrillatory arrest. The average time on cardiopulmonary bypass was 57 min. There were no surgical or anesthetic complications. Two (22%) early deaths occurred due to prosthetic annular size disproportion (1) and preexisting pneumonitis (1); postmortem examination of both implanted devices revealed normal function. The remaining seven animals (78%) remained clinically well and underwent left and right heart catheterization, angiography, and sacrifice after the 150th postoperative day. Left ventriculograms demonstrated normal valve function in all cases. The average mitral transvalvular gradient, as determined by simultaneous pulmonary capillary wedge and left ventricular and diastolic pressure, was 5.4 mm Hg. Thus we have developed a new in vivo model that provides a successful model for chronic evaluation of prosthetic valves using a sheep model. There are several features contributing to the success of our model. First, to decrease the possibility of bacteremia and seeding of the prosthesis, a single incision is used and intraoperative monitoring lines minimized. Second, we use a short cardiopulmonary bypass run (range 52-62 min), with no period of ischemia. Third, fresh sheep blood is transfused immediately following bypass to prevent anemia. Fourth, gastric decompression is used to prevent ruminal bloating, with the resulting vena caval compression that decreases blood return while on bypass.
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PMID:Long-term evaluation of prosthetic mitral valves in sheep. 851 87

Clinicians have few data on which to base a decision to transfuse a surgical patient. We reviewed animal and human data to evaluate the effects that anemia and comorbidity have on surgical outcome. Experimental evidence consistently demonstrates increased cardiac output, decreased peripheral vascular resistance, and increased release of oxygen by red blood cells in response to anemia. Normal animals tolerate hemoglobin (Hb) levels down to approximately 5 g/dL. Below this level, cardiac ischemia and decreased ventricular function develop. In animals with experimental coronary artery stenosis, cardiac ischemia develops at Hb levels of 7-10 g/dL. Coexisting left ventricular hypertrophy, use of beta blockers, and hypoxemia also reduce animals' ability to tolerate anemia. The limited information on anemia tolerance of human surgical patients suggests that the presence of cardiac and pulmonary disease should influence transfusion decisions. A higher Hb threshold should be used in patients who have or are at risk of cardiac or pulmonary artery disease.
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PMID:Morbidity risk assessment in the surgically anemic patient. 854 45

A study was conducted to examine the feasibility of cisplatin-based chemotherapy in elderly patients (> or = 75 years old) with advanced non-small cell lung cancer (NSCLC) or small cell lung cancer (SCLC). Thirty-four patients were enrolled between September 1993 and December 1994. Patients with normal organ function and good performance status (PS) received cisplatin-based chemotherapy (cisplatin 80 mg/m2 on day 1 and vindesine 3 mg/m2 on days 2 and 8 for NSCLC, or cisplatin 80 mg/m2 on day 1 and etoposide 100 mg/m2 on days 2 to 4 for SCLC). Ten patients (29%) were eligible for this study, 7 with NSCLC and 3 with SCLC. Reasons for exclusion were ischemic heart disease in 14, poor PS (> or = 2) in 11, reduced creatinine clearance (Cer) in 10, abnormal electrocardiogram without ischemia in 9 and noncompliance with the protocol in 2 patients. Eight patients had two or more reasons. Nine of the 10 eligible patients were able to tolerate two or more courses of chemotherapy. All 3 patients with SCLC responded (1 complete response and 2 partial response), but only 1 of the patients with NSCLC achieved partial response. Toxicity was evaluated according to Japan Clinical Oncology Group criteria. All but one patient experienced grade 4 neutropenia, and 6 patients had infectious episodes requiring antibiotics. Grade 3 anemia and thrombocytopenia were observed in 1 and 2 patients, respectively. Non-hematological toxicities were mild. Only 10 of 34 patients (29%) satisfied our eligibility criteria and they experienced severe myelotoxicity. We conclude that chemotherapy should be given carefully to elderly patients even if they appear to have normal organ function.
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PMID:Prospective evaluation of the feasibility of cisplatin-based chemotherapy for elderly lung cancer patients with normal organ functions. 863 10

E.Z. former world champion and holder of several gold and silver medals from Olympic Games as long-distance runner, underwent at the age of 71 comprehensive investigations. In 1993 following methods were used to establish E.Z. body build and health: Family, personal and sports history, anthropometry, somatotype, body composition posture values, sports medicine examination, ECG at rest, X-rays of the lung and heart, echocardiography at rest, systolic time intervals at rest, spirography at rest, hematology, biochemistry, X-rays of bones, exercise ECG changes and spiroergometry. Today, a typical feature of E.Z.'s bodybuild is a great amount of body fats, flabby musculature, faulty posture, restricted mobility of the spinal column and surprisingly good foot arches. The clinical findings are appropriate for his age, on his ECG at rest are signs of subendocardial ischemia above the left ventricle, atrial fibrillation and ventricular extrasystoles (Lown 1 a-b). Exercise ECG resulted in a deepening of the ischaemic changes already at a working load of 50 W. Hematology revealed normochromic macrocyt anaemia, biochemistry a borderline mineralogram, hyperuricaemia, higher S-GMT and HDL-C, T-C at the limit of normal values. X-rays of the bones were remarkable in two findings of that age. The pelvis, lumbar spine and knee joints were free of the usual pathological findings (osteoarthrosis), but presented with an exceptionally advanced osteoporosis.
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PMID:Medical and anthropological study of a world and Olympic champion, long-distance runner, 35 years after the end his racing career. 864 15

Although most myocardial infarctions are caused by either obstruction or spasm of the coronary arteries, severe anemia can lower oxygen carrying capacity and damage the myocardium. We report a case of leiomyoma-induced menorrhagia of such severity that myocardial infarction ensued. Hysterectomy was indicated to avoid further anemia. While delaying elective surgery until the heart has had time to recover from infarction is the usual practice, the fact that myoma-induced menorrhagia contributed to ischemia in this patient prompted us to perform hysterectomy shortly after infarction.
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PMID:Management of leiomyoma causing myocardial infarction. 873 Jun 31

Degenerative hip arthritis is caused by the joint failing to bear the normal walk load, because of changes in the anatomical components and of some factors leading to static or dynamic unbalance of the joint surfaces. Degenerative arthritis usually evolves slowly, but its evolution is rapid under certain circumstances and in elderly patients. In such cases destruction is severe and irregular erosions are observed in the femoral heads, which become small and move to the superior lateral edge of the acetabulum. Osteophytes and reactive osteosclerosis are uncommon. Severe pain, functional inability and lower limb shortening are quite constant findings. The patient is often immobilized in bed and risks his/her life. Since the pathogenesis of destructive arthritis is still debated and its clinical features are severe, the knowledge of the natural history and of the underlying factors appears to be very important. The only therapy is arthroprosthesis and prevention becomes, therefore, necessary. On the basis of radiographic findings, we selected three groups of elderly patients hospitalized from 1992 to 1995; of them, 178 had destructive arthritis. The control group consisted of 102 patients with degenerative arthritis and 188 with normal hip joints. The radiographic patterns were related to some clinical and laboratory findings, which are the suspected pathogenetic factors. Two main factors emerged, with high statistical development risk (p < 0.01): hypoxia from femoral head ischemia, due to atherosclerotic vasculopathy and associated anemia, and the articular biodynamic changes which, through minor repeated trauma, cause the lesions, with the appearance of stress fractures.
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PMID:[Destructive arthrosis of the hip. Natural history, pathogenesis, and radiographic features]. 897

Adequate prehospital care of the severely traumatised patient is important to prevent or attenuate early as well as late life threatening complications, such as tissue hypoxia, ischemia/reperfusion injury and finally multiple organ failure. A mismatch of oxygen supply and oxygen demand is a hallmark in the pathophysiology of multiple trauma. Oxygen supply may be diminished by the following factors: shock-related decrease of cardiac output, anemia and hypoxia. On the other hand, oxygen demand may be increased by pain, panic, and agitation. Hence, it is a central point in prehospital care to reduce this supply-demand imbalance by identification and prompt reversal of the underlying causes. Most often, shock is caused by hypovolaemia and tissue injury ("traumatic-hemorrhagic shock"). However, shock may also be a result of central nervous system injury (neurogenic shock as a special form of distributive shock) or circulatory obstruction, e.g tension pneumothorax or cardiac tamponade (obstructive shock). Volume resuscitation by means of crystalloid or colloid solutions is an essential part in the therapy of the traumatic-haemorrhagic shock. In addition, catecholamines may be necessary in order to achieve an adequate arterial pressure. However, if bleeding cannot be controlled in the prehospital setting, only moderate volume support and permissive hypotension as well as rapid transportation into the next hospital may be preferable. This may be the case in penetrating thoracic or abdominal injuries as well as in traumatic amputations of the proximal limb. On the contrary, in patients with severe head injury, hypotension must be avoided by all means. Obstructive shock has to be treated urgently by insertion of a chest drain or drainage of the pericardium, respectively. Under all circumstances, it is an essential part of prehospital therapy to provide sufficient analgesia as soon as possible. Prehospital anesthesia, combined with artificial ventilation may be necessary for optimal patient management. Furthermore, ventilatory support is indicated when respiratory failure, loss of consciousness, or severe shock are present. Additional oxygen should be given whenever possible, even in the absence of an overt hypoxic state. Important additional measures are cervical spine immobilisation and reposition as well as splinting of long bone fractures or luxations, in order to avoid secondary injury of the spinal cord or ongoing tissue and vascular damage.
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PMID:[Emergency management of polytrauma patients]. 902 49

Sickle-cell anemia is a congenital hemolytic anemia characterized by sickle-shaped RBCs. The deformed RBCs become distorted and rigid and may occlude small arterioles and capillaries leading to tissue ischemia and infarction. Sickled RBCs are too fragile to withstand the trauma of circulation, and hemolysis occurs after they enter the circulation. RBCs with a high level of Hb F are resistant to sickling. Hydroxyurea has been shown to stimulate Hb F synthesis, leading to a reduction in the incidence of hemolytic and vaso-occlusive manifestations; however, hydroxyurea has no role in the treatment of crises already in progress. The National Heart, Lung, and Blood Institute announced in January 1995 that treatment with hydroxyurea leads to an increase in Hb F production within RBCs and a reduction in the frequency of painful crises in patients with sickle-cell anemia. Although the mechanism by which hydroxyurea increases Hb F is not known, one possible explanation is that hydroxyurea is cytotoxic to the more rapidly dividing late erythroid precursors, leading to the recruitment of early erythroid precursors that have demonstrated increased capacities to produce Hb F. Clinical trials have demonstrated that hydroxyurea results in an increase in Hb F concentrations; however, this increase may not dramatically affect the progressive vascular changes associated with sickle-cell anemia; thus, patients may still experience complications related to sickle-cell anemia. At North Carolina Baptist Hospital in Winston-Salem, NC, compliant patients with sickle-cell anemia are started on hydroxyurea. There are no specific criteria for patient selection or monitoring. The dosage is started at 10-15 mg/kg/d. Platelet count, complete blood count, and Hb F are monitored and hydroxyurea dosages are adjusted accordingly. Although hydroxyurea has been effective in the treatment of sickle-cell anemia, large double-blind, placebo-controlled clinical trials are needed to determine whether the risks of long-term administration outweight the risk of vaso-occlusive disease in untreated patients.
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PMID:Hydroxyurea in the treatment of sickle-cell anemia. 939 97

Treatment of critical lower limb ischemia in diabetics is often a complex clinical problem for the diabetics' general condition and the local condition of the territory to be revascularized. For these reasons, often the only treatment for diabetics with ischemic-necrotic lesions is amputation. In the symptomatology of arterial disease in diabetics there are three stages: claudication, rest pain, ulcerative-necrotic lesions and two treatment modalities: conservative treatment and revascularization. Conservation is based on the optimization of metabolic control, correction of anemia, control of risk factors, removal of necrotic areas, specific antibiotic treatment based on culture tests. No healing of ulcerative-necrotic lesions after a reasonable period of optimum therapy, quantified in 6 weeks, is suggestive for the presence of absolute or relative ischemia and diagnostic angiography is suitable for the indication for intravascular or surgical revascularization. The latter, in case of diabetics with ischemic complications of the foot, is performed in specialized centers with inverted saphenous veins or in situ in the supragenicular and subgenicular district. Recently intravascular revascularization with balloons, atherotomes, stents, less invasive and less traumatic than bypass revascularization, have become available. At present, with peripheral revascularization, limb salvage at 5-years is feasible in 92% of diabetics with critical lower extremity ischemia.
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PMID:Lower limb revascularization in diabetics. 955 Sep 1

Experiments indicate that capillary density is reduced in the hypertrophied left ventricle of rats with subtotal nephrectomy compared to control rats with similar BP and left ventricular hypertrophy, suggesting that in uremia, hypertrophying cardiomyocytes outgrow their capillary supply. No information on myocardial capillary supply in humans is currently available. The hearts of nine dialyzed patients, nine patients with essential hypertension, and 10 normotensive control subjects at postmortem were obtained. Subjects with stenosing coronary lesions and left ventricular pump failure were excluded. Special sampling procedures were used to exclude stereologic artefacts. Capillaries were specifically stained with ulex lectin and analyzed by stereologic techniques. Length density of myocardial capillaries (Lv; mm/mm3) was significantly (P < 0.001) lower in dialyzed patients (1483 +/- 238) than in patients with essential hypertension (1872 +/- 243) or in normotensive control patients (2898 +/- 456). In parallel, myocyte diameter and volume density of myocardial interstitial tissue were significantly (P < 0.001) increased in uremic patients compared to patients with essential hypertension and control patients, respectively. Diminished left ventricular capillary supply in renal failure must increase critical oxygen diffusion distance in the myocardium, thus exposing cardiomyocytes to the risk of hypoxia. It is unknown whether such reduced ischemia tolerance can be reversed by increasing oxygen supply (e.g., by reversing anemia).
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PMID:Myocyte/capillary mismatch in the heart of uremic patients. 962 Dec 84


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