Biomedical subjects

L Armadans

Publications and source records attributed to L Armadans.

At least 19 recordsLinked to original sources

PubMed2004

Clinical significance of antinuclear antibodies in malignant diseases: association with rheumatic and connective tissue paraneoplastic syndromes.

Our objective was to determine the prevalence of antinuclear antibodies (ANAs) in patients with malignancies and to investigate if their presence might be related with development of musculoskeletal symptoms or paraneoplastic rheumatic syndromes. Antinuclear antibodies were determined by indirect immunofluorescence on Hep-2 cells in 274 neoplastic patients and in a control group of 140 age-adjusted healthy subjects. Antinuclear antibody specificities (anti-DNA and anti-ENA) were investigated in patients with rheumatological symptoms and positive ANA. Antinuclear antibodies were detected in 76 of 274 (27.7%) patients with malignancies and in nine of 140 (6.4%) healthy subjects. Twenty patients reported paraneoplastic rheumatic symptoms or syndromes. Two of them developed clinical symptoms mimicking rheumatoid arthritis (rheumatoid-like arthropathy), one systemic lupus erythematosus (lupus-like syndrome), one dermatomyositis and four cutaneous vasculitides. Musculoskeletal symptoms and paraneoplastic rheumatic symptoms and syndromes were both more frequently observed in patients with positive ANA. Antinuclear antibody specificities were found in only two cases. We can conclude that there is an increased incidence of antinuclear antibodies in malignant conditions. Musculoskeletal symptoms and rheumatic paraneoplastic symptoms and syndromes seem to be more frequent in patients with cancer-related positive ANAs. The failure to find ANA specificities (anti-ENA, anti-DNA) in patients with malignancies and positive ANAs in our study may simply reflect molecular differences between the autoantigens involved in cancer and those characteristically involved in the systemic autoimmune diseases.

Adult↗

PubMed2003

Mortality and prognostic factors in Spanish patients with systemic sclerosis.

OBJECTIVE: To determine survival and mortality in a cohort of Spanish patients with scleroderma (systemic sclerosis, SSc) and to analyse whether survival is influenced by demographic, clinical or immunological variables or the extent of skin involvement. METHODS: The study included 79 patients diagnosed with SSc and taking part in a study to determine the extent of sclerosis, visceral involvement and immunological alterations. We studied the number of observed and expected deaths (the expected number being based on age- and sex-specific rates in the background population) and derived standardized mortality ratios with their 95% confidence intervals (CI). Cumulative survival after onset of the first symptom was estimated according to the Kaplan-Meier method. The Cox method was used to identify the prognostic factors. RESULTS: The mortality rate was 0.0249 deaths per person-year. Survival at 15 yr was 0.62 (95% CI 0.410-0.778). The standardized mortality ratio was 429.4% (95% CI 222-750). On crude analysis, lung involvement [forced vital capacity (FVC) <70%, pulmonary hypertension], SSc renal crisis, an active capillaroscopic pattern, pericardial effusion and age over 60 yr at diagnosis were associated with shorter survival. On multivariate analysis, only age at diagnosis over 60 yr, FVC <70% and SSc renal crisis were independent prognostic factors. CONCLUSIONS: The mortality rate associated with SSc showed a four-fold increase compared with the background population. Lung involvement and sclerodermal renal crisis were found to be independently associated with reduced survival.

Adolescent↗

PubMed2002

Pleural-fluid myeloperoxidase in complicated and noncomplicated parapneumonic pleural effusions.

The diagnostic accuracy of myeloperoxidase (MPO) in pleural fluid, for differentiating between complicated and noncomplicated parapneumonic pleural effusions (PPE) evaluated prospectively. Seventy patients aged >18 yrs with PPE (36 complicated and 34 noncomplicated) were studied after admission to a tertiary referral teaching hospital. MPO concentration was measured in plasma and pleural fluid using a double-antibody competitive radioimmunoassay. The concentrations of MPO in complicated and noncomplicated PPE were compared using a Mann-Whitney U-test and multiple logistic regression models were used to predict the odds that an effusion was complicated. MPO pleural-fluid concentrations were significantly higher in complicated than in noncomplicated PPE. After excluding purulent effusions, pleural-fluid MPO was the marker that best differentiated between the two types of PPE: the area under the receiver operating characteristic curve was 0.912, the sensitivity was 87.5% and the specificity was 85.1% at a cut-point limit of 3.000 microg x L(-1). The authors concluded that the concentration of pleural-fluid myeloperoxidase helps to differentiate between nonpurulent complicated and noncomplicated parapneumonic pleural effusions.

Biomarkers↗

PubMed2001

[Protein-calorie malnutrition and lymphocytopenia as predictors of hospital infection in the elderly].

BACKGROUND: Clinical and epidemiological studies have established that malnutritionis a risk factor for infection in patients being submitted to surgery. To date no study has been carried out to establish the association between the nutritional condition and the incidence of hospital-acquired infections in patients in the medical area. We study the incidence of hospital-acquired infections in the elderly in an attempt to determine the rate of this infection and its association with protein-calorie malnutrition. Another aim of this study has been to determine the predictive value of the parameters used to evaluate the patient's state of nutrition and immunity. PATIENTS AND METHOD: We included 240 patients over 64 years old, 118 males and 122 females, admitted to the medical area of a general hospital. The nutritional and immunity condition of the patients was evaluated through determinations of weight, height, body mass index, hypoalbuminemia and total lymphocyte count. The psichophisical degree of dependence was evaluated through of Norton scale. The details on the hospital infections came from a clinical and microbiological follow-up of patients, in accordance with the criteria of the Centers for Disease Control of Atlanta. RESULTS: The frequency of protein-calorie malnutrition was 12.5% and the accumulated incidence of hospital-acquired infections was 19.6%. Functional incapacity of the elderly prior to hospitalization (odds ratio,4.70; 95% CI: 1.1-19.0) as well as the presence of certain extrinsicrisk factors (odds ratio, 2.35; 95% CI: 1.1-5.1) were, in addition to hypoalbuminemia (odds ratio, 3.60; 95% CI: 1.3-10.2) and lymphocytopenia(odds ratio, 2.67; 95% CI: 1.3-5.7), the independent variables that showed the most significant association with the incidence of hospital-acquired infections. CONCLUSIONS: The nutritional parameters associated with the immune system determinedgreater risk of hospital-acquired infections among elderly patients admitted to the medical area of a hospital. The initial evaluation of elderly patients hospitalitzed in accordance whit the psychophysical degree of dependence based on the Norton scale is useful to evaluate those patients who were at greater risk for hospital infections.

Aged↗

PubMed2001

[Myocardial perfusion SPECT and isotopic ventriculography in obstructive and non-obstructive hypertrophic myocardiopathy].

OBJECTIVE: To evaluate the role of myocardial perfusion SPET and radionuclide ventriculography in patients with hypertrophic cardiomyopathy (HC). METHODS: Exercise myocardial perfusion SPET with 99mTc-tetrofosmin and radionuclide ventriculography were performed in a consecutive series of 101 patients (54 15 years, 50 women, 55 with dynamic obstruction) diagnosed of HC by echo. Follow-up from the diagnosis was 9,9 6,7 years (1 to 28 years). RESULTS: Thirty six percent of patients had perfusion defects (non reversible in 15 and reversible in 21). In non obstructive HC higher number of patients with non reversible defects (p = 0.01 was obseved and in patients with no reversible defects higher incidence of pathologic Q waves in ECG (p = 0.01), Higher ventricular volumes (p < 0.05), lower ejection fraction (p = 0,0001) and longer time to peak emptying velocity (p < 0.05). There were 4 cardiac deaths, 15 syncopes, 18 pacemakers and 6 myectomy. Ejection fraction was higher in patients with syncope (p = 0,034) and there was no isotopic variable predictive of mortality, pacemaker or myectomy. CONCLUSIONS: Neither SPET nor radionuclide ventriculography have a prognostic role in patients with HC, but patients with syncope have higher values of ejection fraction. Patients with non reversible defects have higher rate of pathologic Q waves in ECG, higher ventricular volumes and lower ejection fraction. This is indicative of evolution to dilated form of HC.

Adult↗

PubMed2001

[Value of Doppler-echocardiography in the prognosis and follow up of hypertrophic myocardiopathy].

INTRODUCTION AND OBJECTIVES: The aim of this study was to assess the value of Doppler-echocardiogram for the prognosis and follow up of a hospital-based series of adult patients with hypertrophic cardiomyopathy (HC). METHODS: One-hundred nineteen consecutive patients with HC (52 +/- 12 years, 60 women) were studied over a follow up period of 9.7 +/- 6.7 years. Echocardiographic evolution was analyzed in 104 patients (67 with dynamic obstruction) who had, at least, two echocardiograms performed within an interval of 3.7 +/- 3 years (1 to 7 years). RESULTS: Seven patients died during follow up and 31 patients developed severe complications (7 deaths, 15 syncopes, 4 class IV angina, 3 class IV dyspnea and 2 acute myocardial infarctions). The presence of mitral insufficiency (p = 0.001) and dynamic gradient > 50 mmHg (p = 0.02) were predictive of mortality and a left atrial index > 25 mm/m2 was predictive (p = 0.028) of severe complications. Fifteen percent of the patients without dynamic obstruction in the first Doppler-echo showed a gradient > 25 mmHg in the last echo. A greater number of patients with mitral insufficiency (80% vs 66%; p = 0.01) and an increase in its severity (p = 0.038) was observed during follow up. CONCLUSIONS: Mitral insufficiency, a dynamic gradient > 50 mmHg and a left atrial index > 25 mm/m2 are variables of a bad prognosis in adult patients with HC. An evolution to obstructive HC was observed in 15% of non obstructive HC, and a tendency to increased severity of mitral insufficiency was observed during follow up.

Cardiomyopathy, Hypertrophic↗

PubMed2001

Pleural fluid myeloperoxidase as a marker of infectious pleural effusions.

Background: The aim of this study was to establish the diagnostic accuracy of neutrophil markers (elastase, lysozyme, myeloperoxidase) found in pleural fluid in differentiating between infectious and non-infectious pleural effusions (PE). Methods: We studied 184 patients over 18 years of age with PE, classified as either infectious (34 complicated parapneumonic, 32 non-complicated parapneumonic, 45 tuberculous) or non-infectious (31 neoplasms and 42 undiagnosed exudates). Polymorphonuclear elastase (PMN-E) was determined using an immunoactivation method and lysozyme using a turbidimetric method. Myeloperoxidase (MPO) was measured by double antibody competitive radioimmunoassay. Receiver operating characteristic (ROC) curves were used to evaluate diagnostic accuracy. Results: Pleural fluid MPO was the biochemical marker that best differentiated between infectious and non-infectious PE. The ROC area under the curve (AUC) for myeloperoxidase was 0.86. MPO values over 550 &mgr;g/l diagnosed infectious PE with a specificity of 90.4% and a sensitivity of 77.4%. After excluding purulent parapneumonic PE, the sensitivity of a pleural MPO value >/=550 &mgr;g/l was 72.6%. Conclusions: Pleural fluid MPO was the marker that best differentiated between infectious and non-infectious PE.

Journal Article↗

PubMed2001

Churg-Strauss syndrome: outcome and long-term follow-up of 32 patients.

OBJECTIVES: To study the clinical spectrum and evolution of Churg-Strauss syndrome in order to assess the clinicopathological features of the disease, the response to treatment and the long-term outcome. METHODS: Thirty-two patients with proven allergic and granulomatous angiitis (Churg-Strauss syndrome) and followed up at a single institution were evaluated. They were recruited between 1977 and 1999 from internal medicine departments. Data were obtained retrospectively from medical files in 15 cases and prospectively, using a standardized form, for the remaining patients. RESULTS: All patients had asthma and hypereosinophilia. The lungs, skin and peripheral nervous system were the organs most frequently involved. Antineutrophil cytoplasmic antibodies with antimyeloperoxidase specificity (MPO-ANCA) were detected in 77.8% of tested patients but they were not useful for monitoring disease activity. Extravascular granulomas were rarely seen in tissue biopsies. Forty per cent of the patients were treated with steroids alone. Immunosuppressive agents were added to the treatment when severe neurological, cardiac or gastrointestinal involvement was present. The outcome and long-term survival were good. Clinical relapse was rare after the first year of therapy. Dysaesthesiae of the distal limbs, neurophatic pain and cardiac failure were the most frequent sequelae. CONCLUSIONS: Churg-Strauss syndrome is a rare disorder characterized by hypereosinophilia and systemic vasculitis occurring in patients with asthma and allergic rhinitis. Vasculitis commonly affects the lungs, skin and peripheral nervous system. Outcome and long-term survival is usually good with steroids alone or in combination with immunosuppressive agents. The syndrome has a low mortality rate compared with other systemic vasculitides.

Adolescent↗

PubMed2000

[Residual pleural thickening in tuberculous pleuritis. Associated factors]].

BACKGROUND: To study the factors related to the development of residual pleural thickening in pleural tuberculosis. PATIENTS AND METHODS: We studied 39 patients with tuberculous pleural effusion. A chest X-ray was taken of each patient at the end of treatment. The patients' medical histories, pleural fluid findings and diagnostic chest films were evaluated. Residual pleural thickening was defined as thickening that was visibly greater than 2 mm in the lower side portion of the chest film. RESULTS: Residual pleural thickening developed in 26% of patients and was found mainly in men (RR = 3.86). In no patients with Löwenstein-Jensen cultures positive for Mycobacterium tuberculosis did pleural complications develop. CONCLUSION: Residual pleural thickening is a common complication of tuberculous pleural effusion. Residual pleural thickening in tuberculous pleurisy occurs more often in men and older patients, and in cases in which pleural liquid culture is negative for M. tuberculosis.

Adolescent↗

PubMed2000

[Myocardial SPET in hypertrophic cardiomyopathy].

INTRODUCTION AND OBJECTIVES: The aim of this study was to evaluate the diagnostic accuracy of myocardial SPET in patients with hypertrophic cardiomyopathy (HC). PATIENTS AND METHODS: One hundred and six consecutive patients (aged 53 +/- 12 years, 50 women, 66 with dynamic obstruction) with an echocardiographic diagnosis of HC were studied with exercise-rest myocardial SPET with 99mTc-tetrofosmin. Forty-six (43%) of these patients had chest pain and in 31 (29%) a coronary angiography was performed. Fifty-six per cent of the patients were treated with beta-blockers and 23% with verapamil. RESULTS: Angina during the exercise test was observed in only 8% of the patients. Perfusion defects were observed in 35% of the patients. Only 8 (26%) out of the 31 patients with angiography had coronary artery disease (stenosis > 50%). When fixed and reversible defects were considered as positive, the sensitivity was 50%, the specificity was 65%, the positive predictive value was 33% and the negative predictive value was 79%. CONCLUSIONS: Myocardial perfusion defects can be observed in more than one third of medically treated patients with HC. Only a quarter of catheterized patients, even with chest pain, have associated coronary artery disease. The accuracy of SPET for the diagnosis of coronary artery disease in hypertrophic cardiomyopathy is low. Thus, the value of this technique is limited in these patients.

Aged↗

PubMed2000

The function of permanent vascular access.

BACKGROUND: Complications arising from vascular access (VA) are major causes of morbidity in patients on renal replacement therapy (RRT). They contribute to frustration of health care providers and to high medical cost. To prevent failures in the future it will be helpful to identify the factors that are related to VA malfunction. METHODS: In a retrospective analysis we analysed the types, duration and primary rate of patency of 1033 permanent vascular accesses in 544 consecutive patients established during a 13-year period in a tertiary care hospital. Patient characteristics, incidence, and risk factors related to VA failure were registered. In addition, VA outcomes in patients who started haemodialysis with a catheter and in whom initial VA failure occurred were analysed separately. RESULTS: Forty-five per cent of patients required a central catheter at the start of HD, but 92% of them were being dialysed with an a-v fistula at the last observation. The total number of complications was 0.24 episodes per patient per year at risk and the rate of thrombosis 0.1. A total of 52% of patients were dialysed throughout the observation period with their initial a-v fistula; 9.3% had more than three episodes of VA failure. The radiocephalic a-v fistula was the VA with the best median duration, exceeding 7 years, but also the type that had the highest initial failure rate, i.e. 25% of patients and 13% of the events. The brachiocephalic a-v fistula was the second most frequent type of VA, with a median duration of function of 3.6 years, in contrast to the humerobasilic a-v fistula, which exceeded 5 years. Average patency of the different types of grafts did not exceed 1 year, with the exception of the autologous saphenous graft with a median duration of function of 1.4 years. Patients with glomerulonephritis had the best function rates for their VA, the median exceeding the duration of the study, whereas in half of the diabetic patients it was less than 1 year. The duration of patency of the VA was twice in patients below age 65 years and in elderly males compared to elderly females. Patients who started HD with a catheter, as well as those with initial VA failure, had a higher rate of VA failure in the subsequent course on RRT. CONCLUSION: The radiocephalic and the humerobasilic a-v fistulae are the two types of VA with the longest duration of function, although a high rate of initial failure is seen with the radiocephalic a-v fistula. Age, female gender, presence of diabetic nephropathy, start of dialysis with a catheter, and failure to wait for initial maturation of the VA are risk factors, and account for the majority of VA failures during RRT.

Aged↗

PubMed2000

Diagnostic accuracy of pleural fluid polymorphonuclear elastase in the differentiation between pyogenic bacterial infectious and non-infectious pleural effusions.

BACKGROUND AND OBJECTIVES: To establish the diagnostic accuracy of the markers of neutrophil activity (elastase and lysozyme) determined in pleural fluid, for differentiating between pyogenic bacterial infectious and non-infectious pleural effusions. PATIENTS AND METHODS: At our tertiary referral teaching hospital, 160 patients over 14 years with pleural effusion (PE), classified as pyogenic bacterial infectious (41 parapneumonic complicated, 32 parapneumonic non-complicated) and non-infectious (32 neoplasm and 55 undiagnosed pleural exudates) were examined in a prospective study. Polymorphonuclear elastase (PMN-E) was determined by an immunoactivation method and lysozyme by a turbidimetric method. Receiver operating characteristic (ROC) curves were used to evaluate diagnostic accuracy. RESULTS: Pleural fluid PMN-E was the biochemical marker that best differentiated between pyogenic bacterial infectious and non-infectious PE. The ROC area under the curve (AUC) for PMN-E was 0.8276. A PMN-E value over 230 microg/l diagnosed infectious PE with a specificity of 0.81 and a sensitivity of 0.74. The ROC AUC for proteins plus lactate dehydrogenase was 0. 7430. Differences between the two ROC curves were significant (p = 0. 032). After excluding purulent parapneumonic complicated PE, the sensitivity of a pleural fluid PMN-E value equal to or greater than 230 microg/l was 0.64 and the specificity 0.81. CONCLUSIONS: Pleural fluid PMN-E was the marker that best differentiated infectious from non-infectious PE, and PMN-E values lower than 230 microg/l suggest non-infectious PE.

Adolescent↗

PubMed1999

The value of chest roentgenography in the diagnosis of pneumothorax after thoracentesis.

PURPOSE: We sought to assess the yield of chest roentgenography for the detection of pneumothorax among hospitalized patients with pleural effusion who have undergone diagnostic or therapeutic thoracentesis. SUBJECTS AND METHODS: We performed a prospective study of 506 thoracentesis procedures in 370 patients. After the procedure, each operator filled out a note recording patient data and the characteristics of the thoracentesis. A chest radiograph was performed within 12 hours after the procedure in all patients. RESULTS: Eighteen (4%) pneumothoraces occurred in 17 patients, 9 (2%) of which required chest tube drainage. Of the 488 patients without symptoms, only 5 (1%) developed a pneumothorax, only 1 of which required chest tube drainage. By contrast, of the 18 patients with symptoms, 13 developed a pneumothorax, 8 of which required chest tubes. There were two independent predictors of pneumothorax: presence of symptoms (odds ratio [OR] = 250; 95% confidence interval [CI]: 65 to 980) and male gender (OR = 5.4; 95% CI: 1.9 to 69). CONCLUSIONS: Among the symptom-free patients in our sample, the risk of developing pneumothorax with clinical consequences was so low that the practice of routine chest roentgenography may not be justified.

Chest Tubes↗

PubMed1999

[The impact of the clinical data and the interhospital agreement in the interpretation of myocardial perfusion tomography].

INTRODUCTION AND OBJECTIVES: The aim of this study is to analyze the impact of clinical data and the interhospital agreement in the interpretation of myocardial perfusion single photon emission tomography (SPECT) images and polar mapping. METHODS: 150 patients from 5 hospitals were studied. Each center contributed with tomographic images and polar maps of 99mTc-tetrofosmin exercise SPECT and clinical reports of 30 patients. Thus, 300 images (150 of tomographic images and 150 of polar maps) were interpreted by each center without knowledge of clinical data of the patient ("blinded" report). RESULTS: 90 (60%) out of 150 patients had a coronary stenosis > or = 50%. Sensitivity and specificity of "non blinded" report were 91% and 86%, respectively. Sensitivity determined by majority decision (three or more centers) was 82% for tomographic images and 83% for polar maps (p = 0.002 and p = 0.03, respectively, regarding the "non-blinded" report). Specificity was 88% for tomographic images and 79% for polar map (p = 0.05 with respect to tomographic images). Interhospital agreement was good not only for tomographic images (kappa: 0.625) but for polar maps (kappa: 0.7) as well. CONCLUSIONS: Sensitivity of clinical or "non blinded" report of myocardial perfusion SPECT is significantly higher than the "blinded" report. Specificity of the "blinded" report of polar mapping is lower than that of tomographic images. A good interhospital agreement in interpretation of both types of images was observed.

Aged↗

PubMed1999

[Multicenter study of the variability and adequacy of antimicrobial therapy for community-acquired pneumonia in adults].

We performed a study to evaluate the variability and adequacy of prescribing antibiotics in community-acquired pneumonia (CAP) in 10 Spanish hospitals. We studied 452 patients with CAP. Initial empirical administration of antibiotics was prescribed in 90.7% of the cases, 82.5% as monotherapy. Macrolides and third and second generation cephalosporins were the most widely used groups of antibiotics. Penicillin and amoxicillin were only prescribed in 1. 7% of the patients. A significant variability between hospitals was observed. Reference patterns for the use of antibiotics in CAP were devised by a panel of experts. According to the recommendations of this panel, 29% of the total prescriptions were not adequate, with this percentage reaching 65% in outpatients older than 65 years or with comorbidity. This was mainly due to the fact that monotherapy with erythromycin, which was considered inadequate, was the most widely prescribed treatment.

Adult↗

PubMed1999

[Multicenter study of the variability and adequacy of antimicrobial therapy for community-acquired pneumonia in adults]

We performed a study to evaluate the variability and adequacy of prescribing antibiotics in community-acquired pneumonia (CAP) in 10 Spanish hospitals. We studied 452 patients with CAP. Initial empirical administration of antibiotics was prescribed in 90.7% of the cases, 82.5% as monotherapy. Macrolides and third and second generation cephalosporins were the most widely used groups of antibiotics. Penicillin and amoxicillin were only prescribed in 1.7% of the patients. A significant variability between hospitals was observed. Reference patterns for the use of antibiotics in CAP were devised by a panel of experts. According to the recommendations of this panel, 29% of the total prescriptions were not adequate, with this percentage reaching 65% in outpatients older than 65 years or with comorbidity. This was mainly due to the fact that monotherapy with erythromycin, which was considered inadequate, was the most widely prescribed treatment.

Journal Article↗

PubMed1998

Interleukin-8 and markers of neutrophil degranulation in pleural effusions.

In order to know the degree of interleukin-8 (IL-8) production in the pleural space and its relationship to neutrophil activation, IL-8, neutrophil elastase (NE), and myeloperoxidase (MPO) were assessed in blood and pleural fluid (PF) of 219 patients with pleural effusions. Correlations between blood and PF IL-8, NE, and MPO were either absent or weak, except for IL-8 in transudates (r = 0.6745, p < 0.001). PF IL-8, NE, and MPO concentrations in cases of empyema were higher than in cases of effusion of other causes (p < 0.001). No significant differences in inflammatory markers were observed between parapneumonic and tuberculous fluids. IL-8, NE, and MPO levels in malignant, nonspecific, and transudative effusions were lower than in those due to infection, the lowest levels corresponding to transudates. No significant correlation was observed between PF IL-8 and neutrophil count in any group; in contrast, IL-8 was associated with NE and MPO in empyema (r = 0.7545, and r = 0.7283; p < 0.001), tuberculosis (r = 0.4016, p = 0.008 and r = 0.6545, p < 0.001), and nonspecific effusions (r = 0.3748, p = 0.007 and r = 0.3085, p = 0.028). Our results indicate that local production of markers of the nonspecific inflammatory response is high in both chronic and acute pleural infection, and suggest a role for IL-8 in the release of NE and MPO.

Adolescent↗

PubMed1997

Changes in myocardial electrical impedance induced by coronary artery occlusion in pigs with and without preconditioning: correlation with local ST-segment potential and ventricular arrhythmias.

BACKGROUND: Myocardial ischemia increases tissue electrical resistivity leading to cell-to-cell uncoupling, and this effect is delayed by ischemic preconditioning in isolated myocardium. Alterations in myocardial resistivity elicited by ischemia in vivo may influence arrhythmogenesis and local ST-segment changes, but this is not well known. METHODS AND RESULTS: Myocardial impedance (resistivity [omega x cm] and phase angle [degrees]), epicardial ST segment, and ventricular arrhythmias were analyzed during 4 hours of coronary artery occlusion in 11 anesthetized open-chest pigs; these were compared with 13 other pigs submitted to a similar coronary occlusion preceded by ischemic preconditioning. Myocardial resistivity rose slowly during the first 34+/-7 minutes of occlusion (237+/-41 to 359+/-59 omega x cm), increased rapidly to 488+/-100 omega x cm at 60 minutes, and reached a plateau value (718+/-266 omega x cm, ANOVA; P<.01) at 150+/-69 minutes. By contrast, phase-angle changes began after 17 minutes of ischemia (-3.0+/-1.6 degrees to -4.2+/-1.2 degrees at 29+/-8 minutes) and evolved faster thereafter (-12.5+/-5.3 degrees at 144+/-56 minutes). Marked changes in myocardial impedance were observed during the reversion of ST-segment elevation that occurred 1 to 4 hours after occlusion, but impedance changes were less apparent during the early ST-segment recovery seen at 15 to 35 minutes of ischemia. The second arrhythmia peak (30+/-5 minutes) coincided with the fast change in tissue impedance, and both were delayed (P<.05) by ischemic preconditioning. CONCLUSIONS: A rapid impairment of myocardial impedance occurs after 30 minutes of coronary occlusion, and its onset is better defined by shift in phase angle than by rise in tissue resistivity. Phase 1b arrhythmias are associated with marked impedance changes, and both are delayed by preconditioning. Reversion of ST-segment elevation is partially associated with impairment of myocardial impedance, but other factors play a role as well.

Animals↗