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

We have achieved repeated success with unilateral lung transplantation for pulmonary fibrosis and have developed an en bloc, double-lung transplant procedure for patients with advanced lung disease of an obstructive or infective nature. Six such procedures have now been performed for end-stage emphysema, and all recipients are alive and well 5 to 15 months later. A seventh transplant for primary pulmonary hypertension was unsuccessful. All recipients were judged to have a life expectancy of 12 to 18 months on the basis of the degree of disability and the documented rate of disease progression. We feel the double-lung procedure is more appropriate than the combined heart-lung transplant for patients requiring replacement of both lungs when right heart function is adequate or deemed recoverable. With this procedure, the recipient is able to retain his or her own heart, avoiding the liabilities associated with cardiac transplantation. Furthermore, the donor heart is available for a separate recipient, and this sharing of the heart and lungs greatly increases the supply of transplantable lungs for patients with end-stage lung disease. Ischemia of the donor airway has been a source of complication, including the one death to date, but this appears to be a surmountable problem.
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PMID:Double-lung transplant for advanced chronic obstructive lung disease. 264 98

Phenytoin (diphenylhydantoin, Dilantin, PHT), an anticonvulsant and antiarrhythmic drug, is teratogenic to A/J mice, producing an increased incidence of cleft lip with or without cleft palate [CL(P)] and cardiac defects. Although its mechanism of teratogenic action remains unclear, one possibility may involve uterine ischemia resulting from an exaggerated depressant effect on maternal cardiovascular function. To test this hypothesis, the heart rate response of susceptible A/J and resistant C57Bl/6J mice was monitored following intraperitoneal injection of doses of PHT of known teratogenic potential. Heart rate (HR) was obtained electrocardiographically from unanesthetized, pregnant mice on day 10 of gestation via previously implanted subcutaneous electrodes. The HR of A/J mice was significantly depressed relative to vehicle-injected controls following doses of 40, 60, and 75 mg/kg, with the greatest effect occurring in the high-dose group. In C57Bl/6J mice, the HR response of the group treated with 75 mg/kg was not different from that of the vehicle-treated controls. At the same dose level, the depression of HR of A/J mice was significantly greater in magnitude and duration than that of C57Bl/6J mice. A proposed maternally mediated mechanism of CL(P) in A/J mice involving low placental/embryonic oxygen delivery is discussed. The results of the present study indicate the potential significance that changes in maternal physiology may have on embryonic development.
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PMID:Effect of phenytoin on maternal heart rate in A/J mice: possible role in teratogenesis. 663 88

Ischemia of the donor airway remains a significant cause of morbidity after single-lung transplantation; serious manifestations may occur early (anastomotic dehiscence) or late (stricture). Direct, immediate revascularization of the donor bronchial arteries, using the recipient internal thoracic artery, was performed in 10 consecutive recipients of single-lung transplants for whom we procured the organs. Mean recipient age was 52.6 years (range, 43 to 59 years); 6 were male and 4 female. Recipient diagnoses were emphysema (6), obliterative bronchiolitis (2), pulmonary fibrosis (1), and primary pulmonary hypertension (1). Bronchial artery revascularization initially prolonged the ischemic time by only 15 to 20 minutes; this improved with experience. There was one early death and two late deaths in the series. Internal thoracic arteriography was performed 7 to 10 days postoperatively in all 9 surviving patients. There was excellent perfusion of the donor bronchial arteries in 7 of these 9 patients. Bronchoscopy was performed when clinically indicated. No patient had early or late airway healing complications at a median follow-up of 13 months (range, 6 to 16 months). We conclude that direct, immediate bronchial artery revascularization is feasible on a routine basis for single-lung transplantation, and airway healing has been excellent.
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PMID:Routine immediate direct bronchial artery revascularization for single-lung transplantation. 801 Jul 87

The normal functional state of the vasculature and the events leading to the development of significant arterial disease involve the interaction of important vasoactive substances, which play important modulating or initiating roles in the development of hypertension and arteriosclerosis. Three endothelins have now been identified, of which ET-1 is the best characterized. ET-1 is produced by epithelial, mesangial, neuronal and glial, and liver cells, and is the most potent vasoconstrictor yet found. Each endothelin is derived from a different gene on separate chromosomes, and each binds to at least 2 types of receptor. The plasma half-life of ET-1 is about 7 min, and this provides a rapid mechanism for adjusting vascular resistance or blood pressure. The actions of endothelin are mediated through several pathways of postreceptor signaling, including activation of the mitogen-activated protein kinase cascade, which give rise to its growth-stimulating properties. Secretion of ET-1 from cultured endothelial cells is stimulated by a wide range of substances, and is inhibited by some prostaglandins. Endothelin in turn stimulates secretion of nitric oxide, arginine vasopressin and atrial natriuretic peptide, and participates in the hormonal control of salt and water balance. Hypoxia and ischemia augment ET-1 secretion, as does insulin, and this could play a role in the accelerated vascular disease of diabetes. ET-1 also causes bronchoconstriction and has been implicated in the development of acute asthma, primary pulmonary hypertension and pulmonary fibrosis. Its role in hypertension is still debatable, though most of the manifestations of congestive heart failure can theoretically be explained by the actions of ET-1. Endothelin also has extensive renovascular and parenchymal effects in the kidney. It is hoped that a fuller understanding of the role of endothelins in normal or pathologic vasculature will lead to effective therapy based on antagonism or augmentation of specific functions.
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PMID:Endothelins as cardiovascular peptides. 873 84

To present an overview of the surgical issues in lung transplantation, including the historical context and the rationale for choosing a particular procedure for a specific patient, we reviewed and summarized the current medical literature and our personal experience. Several surgical options are available, including single lung transplantation; double lung transplantation; heart-lung transplantation; bilateral, sequential single lung transplantation; and (recently) single lobe transplantation. Although single lung transplantation is preferred for maximal use of the available organs, bilateral lung transplantation is necessary for septic lung diseases and may be appropriate for pulmonary hypertension and bullous emphysema. Heart-lung transplantation is performed for Eisenmenger's syndrome and for primary pulmonary hypertension with severe right ventricular failure. General factors for consideration in assessment of compatibility of the donor and potential recipient include ABO blood group, height (the donor should be within +/- 20% of the recipient's height), and length of the lungs (determined on an anteroposterior chest roentgenogram). Graft preservation and minimal duration of ischemia are important. Complications associated with airway healing are related to ischemia of the donor bronchus. We have addressed the issue of donor bronchial ischemia by direct revascularization of the donor bronchial arteries with use of the recipient's internal thoracic artery. Currently, lung transplantation offers a realistic therapeutic option to patients with end-stage pulmonary parenchymal or vascular disease.
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PMID:Surgical issues in lung transplantation: options, donor selection, graft preservation, and airway healing. 900 92

Longitudinal studies of large cohorts of patients with Raynaud's Phenomenon have addressed the predictors of developing a secondary disease. New insights have been reported into the pathogenesis of Raynaud's phenomenon and the consequences of ischemia. Studies have suggested that more than one defect may cause Raynaud's phenomenon, including increased alpha-2 sympathetic receptor activity on vessels, endothelial dysfunction, deficiency of calcitonin gene related peptide protein--containing nerves or some central thermoregulatory defect. The vasoconstricting and profibrotic cytokine endothelin-1 was found to be elevated in scleroderma but did not correlate with disease subset or with evidence of pulmonary hypertension. Oxidant stress is thought to be increased in scleroderma, causing tissue damage and provoking fibrosis. Treatment with infusion of prostacyclin for primary pulmonary hypertension was approved, paving the way for studies of secondary forms of pulmonary hypertension. Oral prostanoids are being tested for the treatment of Raynaud's phenomenon.
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PMID:Raynaud's phenomenon and other features of scleroderma, including pulmonary hypertension. 901 60

Appetite suppressants, such as dexfenfluramine (dex), are associated with primary pulmonary hypertension, valvular heart disease, and systemic vascular complications, such as coronary, cerebral, or mesenteric ischemia. These drugs suppress appetite by enhancing release and inhibiting reuptake of serotonin in the central nervous system. The effects of dex on the systemic circulation have not been studied. K(+) channels regulate vascular tone in most vascular beds. We hypothesized that dex is a systemic vasoconstrictor acting primarily by inhibiting K(+) channels, independent of effects on serotonin. The effects of clinically relevant concentrations of dex (10(-6) to 10(-4) M) on outward K(+) current and membrane potential were studied with whole-cell patch clamping in freshly isolated smooth muscle cells from rat renal, carotid, and basilar arteries. Tone was measured in tissue baths. Blood pressure, cardiac output, and left ventricular end diastolic pressure were assessed in open- and closed-chest anesthetized rats. At 10(-4) M, dex inhibits outward K(+) current (50%) and increases membrane potential (by >35 mV), an effect comparable with 4-aminopyridine (5 mM). Furthermore, dex constricts rings and acutely elevates systemic pressure (+17 +/- 3 mm Hg) and systemic vascular resistance in the presence of ketanserin. Dex vasoconstriction is dose-dependent (threshold dose 10(-6) M; 156 microg/ml) and enhanced in L-NAME-fed rats. We conclude that dex causes acute systemic vasoconstriction, at least in part by inhibition of voltage-gated K(+) channels, independent of effects on serotonin. To our knowledge, this is the first time that a commonly prescribed drug with voltage-gated K(+) channel-blocking properties is shown to have significant hemodynamic effects in vivo.
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PMID:Dexfenfluramine elevates systemic blood pressure by inhibiting potassium currents in vascular smooth muscle cells. 1056 35

The present review is focused on chronic RV pressure overload or Cor Pulmonale as it may occur in the setting of two distinct disorders: those associated with abnormal pulmonary gas exchange (hypoxemia and/or hypercapnia) where chronic obstructive pulmonary disease (COPD) is the leading cause, and those associated with pulmonary vascular obstruction where primary pulmonary hypertension (PDDH) is the representative example. The clinical curse, prognostic, implications, and therapeutic strategies differ considerably in these two clinical entities. Right ventricular failure (RVF) may adversely influence the natural history and prognosis of patients with diverse cardiopulmonary disorders. It has been long established that right ventricular (RV) ischemia, RV overload, and RV pressure overload, alone or in combination, are the main factors involved in the pathogenesis of RVF. From the pathophysiologic point of view, RVF of COPD is more a congestive type of failure, in which activation of renin-angiotensin system is involved. In PPH, a low cardiac output state is predominant and the precise mechanism of RVF remains unknown. Current evidence in favor of the pathogenetic role of ischemia, adrenergic overdrive, and genetic determination are all reviewed during the course.
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PMID:[Right ventricle insufficiency in pulmonary arterial hypertension. Physiopathologic considerations]. 1156 26

Angina is a common symptom of severe pulmonary hypertension. Although many theories for the source of this pain have been proposed, right ventricular ischemia is the one most commonly accepted as the cause. We report on two patients with primary pulmonary hypertension who had angina with normal activity or on provocation. One patient had severe left ventricular dysfunction. Both were found to have severe ostial stenosis of the left main coronary artery as a result of compression from a dilated pulmonary artery. Both patients underwent stenting of the left main coronary artery with excellent angiographic results, and complete resolution of the signs and symptoms of angina and left ventricular ischemia. Left ventricular ischemia due to compression of the left main coronary artery may be a much more common mechanism of angina and left ventricular dysfunction in patients with pulmonary hypertension than previously acknowledged. Stenting of the coronary artery can be done safely with the resolution of these symptoms.
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PMID:Stenting to reverse left ventricular ischemia due to left main coronary artery compression in primary pulmonary hypertension. 1159 92

The electrophysiological criteria for diagnosing right ventricular hypertrophy, characteristic of chronic cor pulmonale, are described. Right ventricular hypertrophy due to a sustained systolic overload can be global or regional. In the first situation, as for example, an idiopathic pulmonary hypertension, the magnitude and manifestation of all the main vectors resulting from the depolarization of this ventricle are increased: Ils (septal), llr (parietal), and Illr (basal). When the right ventricular hypertrophy is of the segmental (regional) type, as for example, that due to a chronic bronchial obstruction, the magnitude and manifestation of only some right vectors are increased. In this condition, only the magnitude of the right basal vector (Illr) is augmented. In the presence of subepicardial or transmural ischemia of the right ventricle, negative T waves of primary type are recorded in right precordial and transitional leads, where the Q-Tc interval is prolonged in the absence of digitalis effect. Two demonstrative examples of the correlations existing between the electrocardiographic and anatomical findings in global and regional hypertrophies, respectively, of the right ventricle are presented.
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PMID:[Electrocardiographic features of right ventricular hypertrophy in chronic cor pulmonale]. 1674 5


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