[Publication trends in quarterly, bimonthly and monthly cycles of publication during the five decades of Brazilian Archives of Cardiology]. / Tendências das publicações nas fases trimestral, bimestral e mensal das cinco décadas dos Arquivos Brasileiros de Cardiologia.

OBJECTIVE: To study trends in selected manuscript characteristics of articles published in the Brazilian Archives of Cardiology from March 1948, to February 1998, in the quarterly, bimonthly and monthly cycles of publication. METHODS: A random sample of 25% of all issues of the journal comprised the study sample: 13 issues (11.5%) from the quarterly, 27 (23,5%) from the bimonthly, and 58 (65%) from the monthly publication cycle. We studied the type of manuscript, number of authors, geographical distribution, language of publication and references. RESULTS: A total of 1204 articles were studied, 90 (7.5%) from the quarterly, 238 (19,8%) from the bimonthly, and 876 (72.8%) from the monthly publication cycle. The most frequent published articles were original contributions (353), reviews (350) and case reports (205). No significant difference occurred in the proportion of original articles, reviews and case reports; the number of authors was higher in the monthly period;a geographical concentration of the contributions occurred (72% from three Brazilian States); manuscripts in languages other than Portuguese decreased. The mean number of Brazilian references cited was less than 4.7 and the mean number of international references cited was greater than 16.7. CONCLUSION: The analysis of the trends over five decades of publication revealed the need for further steps to be taken by the Brazilian Archives of Cardiology, to meet international publication standards for biomedical journals as well as authors' and readers' demands.

[Analysis of adequacy and effectiveness in the use of tocolytics in preterm labor]. / Anlise da adequação e da efetividade do uso de tocolíticos no trabalho de parto prematuro.

The objective of this study was to assess quality of care for premature labor at public maternity facilities in Rio de Janeiro, Brazil, using referents, indicators, and standards of care derived from scientific evidence. The standard utilized in the process analysis for use of betamimetic tocolytics was 100%, considering the related referents. For outcome analysis, the standard applied was the occurrence of premature delivery in 11% of patients within 24 h and in 24% of patients (referent) within 48 h of hospital admission. Use of tocolytics was observed in 18.7% of patients admitted in premature labor. At gestational age from 28 weeks to 33 weeks and 6 days, especially critical for neonatal survival, tocolytics were used in 32.6% of patients. Premature birth occurred in 59% of patients within 24 h and in 64% within 48 h. These outcomes were consistent with the low rate of utilization of tocolytics. Effectiveness of care for preterm labor measured by rate of premature birth was low. Results of the corresponding process and outcomes analysis were consistent.

[Assessment of quality of obstetric hospital care: use of corticoid in preterm labor]. / Avaliação da qualidade da assistência hospitalar obstétrica: uso de corticóides no trabalho de parto prematuro.

This study aimed to assess quality of obstetric care for preterm labor patients, using referents, indicators, and standards derived from scientific evidence, focusing on antenatal corticotherapy. Available meta-analyses and randomized controlled trials were examined to establish referents, defining indicators and estimating process and outcome standards for the present study. Data from hospital discharge summaries of seven public maternity hospitals in Rio de Janeiro were analyzed. The standard of process used was 100%. It was not possible to estimate outcome standards, since the necessary adjustment for gestational age was not feasible. Utilization of antenatal corticotherapy in the present study was very low, about 4% and 2%, considering patients up to 33 weeks and 6 days and 36 weeks and 6 days, respectively. Failure to use antenatal corticotherapy when formally indicated deserves attention by health planners and managers, considering: a) the ease in incorporating such a technology, in contrast to the adequate incorporation of special/intensive neonatal care; b) benefits and costs associated with this technology compared to those of delivering neonatal care to premature babies.

Normal high energy phosphate ratios in "stunned" human myocardium.

OBJECTIVES: We sought to investigate whether alterations in cardiac high energy phosphates occur in postischemic "stunned" human myocardium. BACKGROUND: Transient postischemic myocardial dysfunction is a common phenomenon that occurs in a variety of clinical settings in the absence of necrosis, and its pathogenesis is still unclear. Cardiac high energy phosphates are reduced during ischemia, and persistently altered myocardial high energy phosphate metabolism has been suggested as a mechanism contributing to stunning. METHODS: We studied 29 patients with a first anterior myocardial infarction (MI) who underwent successful reperfusion within 6 h of the onset of chest pain. These patients underwent 31P magnetic resonance spectroscopy (MRS) a mean of 4 days after MI for measurement of left ventricular contractility and relative high energy phosphate metabolites. Twenty-one patients underwent a second 31P MRS study a mean of 39 days after MI. Eight volunteers served as control subjects. RESULTS: Global and infarct area wall motion scores improved significantly between the early and late studies. No difference was found between early cardiac phosphocreatine (PCr)/beta-adenosine triphosphate (beta-ATP) ratios in patients and control subjects ([mean +/- SD] 1.51 +/- 0.17 vs. 1.61 +/- 0.18, respectively, p = 0.17) or between early and late study results in patients (1.51 +/- 0.17 vs. 1.53 +/- 0.17, respectively, p = 0.6). For alpha of 0.05, the study had a 90% power to detect a 9% difference. CONCLUSIONS: The results of this study demonstrate normal myocardial PCr/ATP ratios in patients with myocardial stunning after reperfusion and suggest that relative cardiac high energy phosphates are not depleted in stunned human myocardium.

Role of preischemic glycogen depletion in the improvement of postischemic metabolic and contractile recovery of ischemia-preconditioned rat hearts.

BACKGROUND: Ischemic preconditioning (IPC) attenuates acidosis during prolonged ischemia and improves contractile and metabolic parameters during subsequent reperfusion. Glycogen depletion induced by IPC is proposed as a potential mechanism. METHODS AND RESULTS: We studied the influence of manipulations of preischemic glycogen levels (Pre-G, micromol glucose/g wet wt) on contractile and metabolic (via 31P-nuclear magnetic resonance) parameters during 30 minutes of ischemia and recovery in four groups of isovolumic rat hearts: First, control (Con, n=18, mean Pre-G, 21.5+/-0.8); second, after two 5-minute IPC periods (IPC, n=12, Pre-G, 11.3+/-0.7); third, a control group in which Pre-G was depleted by glucose-free, acetate perfusion (Con-LowG, n=9, Pre-G, 7.9+/-1.2); and fourth, an IPC group in which Pre-G was raised by glucose and lactate perfusion such that Pre-G was similar to Con (IPC-HiG, n=11, Pre-G, 20+/-1.4). Manipulation of Pre-G significantly altered the pH fall during 30 minutes of ischemia (Con, 5.76+/-.03, Con-LowG, 6.26+/-.07; IPC-HiG, 5.91+/-.02, IPC, 6.05+/-.09). IPC-HiG hearts had significantly worse metabolic recovery (PCr, 70+/-7 versus 91+/-3% initial; IPC-HiG versus IPC, P<.05) and contractile recovery (end-diastolic pressure, 52+/-5 versus 29+/-5 mm Hg, P<.05) than IPC hearts but better recovery than Con (%PCr, 56+/-6% and end-diastolic pressure, 72+/-6 mm Hg). An ischemic rise in intracellular magnesium occurred and was atttenuated in preconditioned hearts. CONCLUSIONS: Pre-G levels before ischemia influence but are not the sole determinants of the extent of acidosis during prolonged ischemia and of metabolic and contractile recovery during reperfusion in control and preconditioned hearts.

Usefulness of ST-segment depression in non-infarct-related electrocardiographic leads in predicting prognosis after thrombolytic therapy for acute myocardial infarction.

This study investigated both the in-hospital and long-term prognostic significance of ST-segment depression in non-infarct-related leads in patients who received thrombolytic therapy after acute myocardial infarction (AMI). We evaluated 221 consecutive patients who were admitted with their first AMI and underwent thrombolysis. Patients were followed for an average of 31 months and were classified into 3 groups: group 1 included 51 patients with persistent ST-segment depression, group 2 had 97 patients with transient ST-segment depression, and group 3 consisted of 73 patients without ST-segment depression (absent). Group 1 had significantly worse long-term survival during follow up by Kaplan-Meier analysis (55%) versus group 2 (81%) and group 3 (94%) (p = 0.0004) and higher event rates. This prognostic significance seemed to be maintained in both the anterior and inferior wall AMI groups. Multivariate analysis, using the Cox model, showed that Killip class, in-hospital left ventricular ejection fraction, and the persistence of ST-segment depression on the predischarge electrocardiogram (group 1) were independent predictors of survival. ST-segment depression in non-infarct-related leads on the predischarge electrocardiogram is an independent risk factor for worse long-term survival after anterior as well as inferior AMI treated with thrombolytic therapy.

Attenuated glycogenolysis reduces glycolytic catabolite accumulation during ischemia in preconditioned rat hearts.

Prior transient episodes of ischemia ("ischemic preconditioning") reduce lactate accumulation and attenuate acidosis during a subsequent prolonged ischemic insult. The mechanisms responsible for attenuated glycolytic catabolite accumulation have not been established but may include earlier exhaustion of glycogen stores, slowed glycogenolysis before complete glycogen depletion, and/or inhibition of glycolysis. Simultaneous repeated measures of myocardial glycogen and the rates of glycolysis, glycogenolysis, glucose utilization, and glycolytic ATP production were obtained during total ischemia by 13C nuclear magnetic resonance spectroscopy in control and ischemia-preconditioned isolated rat hearts. Both [13C]glycolytic and [13C]glycogenolytic rates were significantly lower during total ischemia in preconditioned compared with control hearts (0.77 +/- 0.04 versus 1.06 +/- 0.06 mumol/min per gram wet weight [P < .01] for glycolysis and 0.15 +/- 0.07 versus 0.78 +/- 0.12 mumol/ min per gram wet weight [P < .001] for glycogenolysis, respectively, at 2.5 minutes of ischemia). Slowed glycolysis was present even during the early minutes of ischemia, when significant amounts of available [13C]glycogen were still present. Importantly, the reduction in the rate of glycogenolysis was larger and out of proportion to the reduction in glycolysis and occurred despite an increase in glucose utilization in preconditioned hearts (2.23 +/- 0.15 versus 1.5 +/- 0.10 mumol/min per gram wet weight at 1.25 minutes, P < .01). During early ischemia, conversion of glycogen phosphorylase to the a or "active" form was less in preconditioned than in control hearts (29.1 +/- 2.6% versus 41.2 +/- 9.8%, respectively; P < .05). Taken together, these findings demonstrate that ischemic preconditioning significantly depresses glycolytic catabolite accumulation during sustained ischemia not by more severe glycolytic inhibition or exhaustion of glycogen stores but by depressed glycogenolysis from the onset of ischemia.

Valor do precondicionamento isquêmico na circulaçäo colateral, funçäo ventrícular e evoluçäo clínica no infarto agudo do miocárdio / The effecft of ischemic preconditioning on collateral circulation, ventricular function and clinical outcomes after acute

Objetivo - Avaliar a influência do precondicionamento isquêmico no fenômeno do desenvolvimento de circulaçäo colateral (CC), na funçäo ventrícular precoce e na evoluçäo hospitalar de pacientes com infarto agudo do miocárdio (IAM). Métodos - Foram estudados 97 pacientes com IAM anterior nas primeiras 6h, com oclusäo proximal da artéria coronária descendente anterior e divididos em 2 grupos na dependência da presença (GA) ou ausência (GB) de angina precedendo o IAM. Coronariografia e ventriculografiaoram realizadas nas primeiras 6h , antes de qualquer tentativa de reperfusäo. A fraçäo de ejeçäo global do ventrículo esquerdo (FEVE), foi obtida através do método de áreas e a funçäo regional da parede anterior anterior através da linha do centro. Resultados - Os grupos foram superponíveis em relaçäo ao sexo, idade, pico de CKMB, tratamento instituído (perfusäo química ou mecânica) e sucesso na reperfusäo. A média da FEVE e a mobilidade da parede anterior foram similares nos 2 gupos, respectivamente, 3+_9 por cento e -2,55+/_1,17 dp/corda no GA e 37 por cento+/_8 por cento e -2,75+/_0,79 dp/corda no GB (p=ns). A CC esteve presente em 6 pacientes do GA e em 8 do GB (p=ns). A evoluçäo clínica foi melhor no GA (todos Killip classe 1) em comparçäo ao GB (8 pacientes Killip > ou igual a 2) p=0,007. Conclusäo - Embora näo exista diferença entre os grupos em relaçäo a presença de CC, funçäo ventricular e regional do ventrículo esquerdo, a presença de angina precedendo o infarto associado à melhor evoluçäo hsptalar, a qual poderia em parte ser explicada pelo fenômeno denominado precondicionamento esquêmico.

Análise da retração elástica nos primeiros 15 minutos após angioplastia coronária por cateter balão / Elastic recoil in the firt 15 minutes following a successfull balloon angioplasty

Objetivo - Determinar angiograficamente a retraçäo elástica (RE) nos primeiros 15 minutos após angioplastia coronária (AC) por cateter baläo. Métodos - E um estudo prospectivo, 154 pacientes, portadores de angina estável, foram submetidos a AC com sucesso. Realizaram-se angiografias imediatamente após a última insuflaçäo com sucesso e aos 5,10 e 15 min. Na análise quantitativa utilizou-se caliper eletrônico. Quantificaram-se o diâmetro luminal mínimo (DLM) e a RE no controle imediato, aos 5, 10 e 1min. Relacionaram-se a magnitude da RE e o DLM com as características angiográficas da lesäo tratada, com o diâmetro do baläo e com o grau de lesäo residual imediatamente após a AC. Resultados - O diâmetro de referência médio do vaso foi de 3,09+/_0,61 mm e o diâmetro do baläo de 2,95+/_0,52 mm. O DLM mínimo pré dilataçäo foi de 0,65+/_0,42 mm, atingindo 2,23+/_0,55 mm após a dilataçäo (p<0,0001), decrescendo para 2,09+/_0,47 mm e 5 min (p<0,0001), 2,01+/_0,47 mm em 10 min (p<0,0001) e para1,91+/_0,56 mem 15 min. (p<0,0001). A RE aumentou progressivamente, atingindo 34,29+/_20,40 por cento aos 15 min. Nos vaso tratados onde a relaçäo baläo/artéria < ou igual a 1 a RE foi de 0,90+/_0,74 mm em 15 min. e de 1,20+/_0,50 mm quando a relaçäo foi >1 (p<0,0001). Identificou-se maior RE nos primeiros 15 min. no grupo de pacientes onde a lesäo residual no controle imediato situou-se entre 30 a 50 por cento do que no grupo onde a lesäo residual foi < 30 por cento. Conclusäo - A RE é um fenômeno dinâmico e progrssvo que ocorre dentro de 15 min. após a AC com sucesso. Determinou reduçäo média de 34,29+/_20,40 por cento no diâmetro do vaso em 15 min. e é maior quando a relaçäo baläo/artéria é >1. A lesäo residual que situa entre 30 e 50 por cento no controle angiográfico imediato é fator preditor de maior RE ao longo dos 15 min.

The Medicine, Angioplasty or Surgery Study (MASS): a prospective, randomized trial of medical therapy, balloon angioplasty or bypass surgery for single proximal left anterior descending artery stenoses.

OBJECTIVES: This study sought to evaluate, in a prospective and randomized trial, the relative efficacies of three possible therapeutic strategies for patients with a single severe proximal stenosis of the left anterior descending coronary artery and stable angina. BACKGROUND: Although percutaneous transluminal coronary angioplasty and coronary artery bypass surgery are often performed in patients with a single proximal stenosis of the left anterior descending coronary artery, it is unclear whether revascularization offers greater clinical benefit than medical therapy alone. METHODS: At a single center, 214 patients with stable angina, normal ventricular function and a proximal stenosis of the left anterior descending coronary artery > 80% were randomly assigned to undergo mammary bypass surgery (n = 70), balloon angioplasty (n = 72) or medical therapy alone (n = 72). Angioplasty had to be considered technically feasible in every case. The predefined primary study end point was the combined incidence of cardiac death, myocardial infarction or refractory angina requiring revascularization. RESULTS: At an average follow-up period of 3 years, a primary end point had occurred in only 2 patients (3%) assigned to bypass surgery compared with 17 assigned to angioplasty (24%) and 12 assigned to medical therapy (17%) (p = 0.0002, angioplasty vs. bypass surgery; p = 0.006, bypass surgery vs. medical treatment; p = 0.28, angioplasty vs. medical treatment, all by log-rank test). There was no difference in mortality or infarction rates among the groups. However, no patient allocated to bypass surgery needed revascularization, compared with eight and seven patients assigned, respectively, to coronary angioplasty and medical treatment (p = 0.019). Both revascularization techniques resulted in greater symptomatic relief and a lower incidence of ischemia on the treadmill test; however, all three strategies eventually resulted in the abolition of limiting angina. CONCLUSIONS: The more aggressive therapeutic approach with initial bypass surgery for patients with a single severe proximal stenosis of the left anterior descending coronary artery is associated with a lower incidence of medium-term adverse events than coronary angioplasty or medical treatment. However, all three strategies resulted in a similar incidence of death and infarction during an average follow-up period of 3 years. This information should be taken into consideration when physicians and patients make therapeutic choices in this setting.

[Magnetic resonance imaging in chronic Chagas cardiopathy. Correlation with endomyocardial biopsy findings]. / Imagem por ressonância magnética na cardiopatia chagásica crônica. Correlação com biopsia endomiocárdica.

PURPOSE: To study the correlation between magnetic resonance imaging of the heart and right ventricle endomyocardial biopsy results in chronic Chagas' heart disease. METHODS: Ten patients with Chagas' disease, mean age 47 +/- 7 years, all males, in congestive heart failure with New York Heart Association class II (2 patients), III (6) and IV (2) were studied. Mean left ventricular ejection fraction was at echocardiogram 36 +/- 6%. The patients were submitted to right ventricular endomyocardial biopsy and magnetic resonance imaging of the heart. The results of this group were compared with a control group of patients with idiopathic dilated cardiomyopathy, with mean age of 46 +/- 10 years and left ventricular ejection fraction of 30 +/- 4%, in heart failure with functional class II (1 patient), III (5) and IV (1). RESULTS: All patients with Chagas' heart disease presented an increase in magnetic ressonance imaging signal of the heart after gadolinium use. The septal signal intensity changed from 0.87 +/- 0.06 to 1.54 +/- 0.16 (p < 0.001). In the control group the mean septal signal intensity was 0.93 +/- 0.07 before and 0.89 +/- 0.06 after the gadolinium (p = ns). Eight patients of the Chagas' disease group had biopsy proven myocarditis and two had borderline myocarditis. However, only one patient of the control group had diagnosis of borderline myocarditis. CONCLUSION: Myocarditis is frequently found in Chagas' heart disease patients and who unlike controls present a significant increase in myocardial signal intensity after gadolinium infusion. The magnetic resonance imaging of the heart seems a promising alternative method for the diagnosis of an inflammatory process in Chagas' heart disease.

[Role of circumflex coronary artery involvement in non-Q wave myocardial infarction]. / Papel do acometimento da artéria coronária circunflexa no infarto do miocárdio sem onda Q.

PURPOSE: To determine the patency and incidence rates of left circumflex coronary artery (LCX) as the infarct related artery (IRA) in Q-wave and non-Q wave acute myocardial infarction (AMI). METHODS: Two-hundreds and twenty one patients (172 men) with AMI were stratified in Q and non-Q waves groups. All patients were submitted to cinecoronary angiography 72 hours after the beginning of symptoms and the IRA and its patency were evaluated. RESULTS: In non-Q wave AMI, the LCX was considered to be the IRA in 35% of the patients. In Q wave AMI, this incidence was 8% (p < 0.001). Occlusion of LCX was seen in all non-Q wave AMI patients when it was the IRA. CONCLUSION: The incidence of LCX as IRA was significantly higher in non-Q wave AMI patients. This group did not have the previously expected greater patency rates, what could result in different clinical and evolutive characteristics.

[Hospital outcome of patients with right ventricular infarction and the importance of right coronary artery patency]. / Evolução hospitalar de pacientes com infarto de ventrículo direito e a importância da perviabilidade da artéria coronária direita.

PURPOSE: To evaluate the importance of the right coronary artery (RCA) patency in patients with right ventricular infarction. METHODS: Fifty-two patients with inferior wall myocardial infarction and right ventricular involvement were studied and divided in two groups: group A (GA) included 35 patients in whom the RCA was patent at coronary angiography, and group B (GB), 17 who had an occluded RCA. They were prospectively evaluated for electrical and hemodynamic complications, as well as in-hospital mortality. RESULTS: The mortality in GA was 11% and 29% in GB, p = 0.13; electrical complications were 11% in GA and 35% in GB, p = 0.06; hemodynamic complications were 8% in GA and 41% in GB, p = 0.009. CONCLUSION: These findings suggest a trend towards reduction in mortality and electrical complications, and significant reduction of hemodynamic complications in patients with inferior wall myocardial infarction with involvement of the right ventricle who have the RCA patent. Thus, RCA patency appears to be important in determining in-hospital outcomes of these patients.

Consequences of altered aspartate aminotransferase activity on 13C-glutamate labelling by the tricarboxylic acid cycle in intact rat hearts.

The appearance of 13C label in glutamate has been used to quantify cellular tricarboxylic acid (TCA) cycle activity using 13C-NMR spectroscopy. Glutamate is linked to the TCA cycle by the amino-transferase reactions, however the consequences of alterations in amino-transferase activity on glutamate labelling kinetics, at a constant total tricarboxylic acid cycle activity, have not been investigated. Aspartate amino-transferase activity in [2-13C]acetate-perfused beating rat hearts was found to be similar to total TCA cycle flux in the presence of normal perfusion conditions and was reduced by more than 50% with the subsequent administration of amino-oxyacetic acid (AOA). AOA did not reduce contractile or kinetic measures of total TCA cycle flux, but did slow the 13C labelling of glutamate, in accord with current mathematical predictions. The impact of similar reductions in amino-transferase activity on estimates of total TCA cycle flux derived from several previously reported methods was also evaluated. Because total TCA cycle and the amino-transferase activities both affect the kinetics of 13C-glutamate labelling and because the amino-transferase activities are often unknown under physiologic conditions and can be reduced under pathologic conditions, the calculation of total TCA cycle flux from 13C-NMR data in the future is probably best accomplished either with a sufficiently sophisticated mathematical model that assesses amino-transferase activity or with an empiric model that is relatively insensitive to variations in amino-transferase activity.

[Significance of the nuclear magnetic resonance in the detection of coronary artery patency after thrombolysis]. / Valor da ressonância nuclear magnética na detecção da perviabilidade da artéria coronária após trombólise.

PURPOSE: To determine the value of magnetic resonance imaging (MRI) in the noninvasive detection of infarct related coronary artery patency after thrombolysis. METHODS: We studied 26 patients with acute myocardial infarction submitted to thrombolysis underwent MRI studies before and after 0.1mmol/kg gadolinium-DTPA injection within the first 48 h of MI. Signal intensity was assessed by circumferential profile analysis techniques. RESULTS: The average ratio of signal intensity of infarcted tissue over normal myocardium (I/N) was significantly higher in patients with patent arteries (1.3 +/- 0.13 vs 1.12 +/- 0.07, p < 0.02). Compared to coronariography MRI, sensitivity of 81% and specificity of 100% for the diagnosis of coronary patency. CONCLUSION: Gadolinium infusion increased infarcted and normal myocardium differentiation. The study of gadolinium kinetics at MRI is a promising technique for noninvasive diagnosis of coronary patency.

Magnetic resonance imaging in Chagas' heart disease.

Many important aspects of Chagas' heart disease can be successfully assessed using magnetic resonance imaging of the heart. It is possible to obtain with great detail the anatomic characterization of the cardiac as well as important information of the functional or metabolic status of the heart. Magnetic resonance imaging after gadolinium infusion seems also a promising technique to obtain a better regional characterization of myocardial tissue, and may be important in the non-invasive diagnosis of active myocarditis in patients with Chagas' heart disease.

Long-term function in the remote region after myocardial infarction: importance of significant coronary stenoses in the non-infarct-related artery.

BACKGROUND: Left ventricular (LV) function is the most important determinant of outcome after a myocardial infarction. Global LV function after a myocardial infarction is affected not only by wall motion in the infarct zone but also by regional function in the contralateral territory. It was hypothesised that the presence of significant stenoses in coronary arteries supplying the contralateral territory might influence the ability of this region to compensate for damaged myocardium after a myocardial infarction. METHODS AND RESULTS: 79 patients treated with thrombolysis for acute myocardial infarction had coronary and ventricular angiograms within 24 h and at a mean follow up of 12 months after myocardial infarction. Wall motion in the contralateral territory was analysed and scored by the centre line method and the change over time was correlated with the presence or absence of significant (> 70%) diameter stenoses in the non-infarct-related artery. Mean (SD) contralateral territory motion worsened, from 0.74 (1.78) to -1.55 (2.06) SD chord (p < 0.001) in 40 patients with stenoses, whereas contralateral territory motion improved from -0.02 (2.4) to 0.63 (2.21) SD chord (p < 0.05) in the 39 patients without coronary stenoses. The same pattern was present whether or not the infarct artery was patent. The global left ventricular ejection fraction at 12 months was also related to contralateral territory motion (r = 0.71, p < 0.001) and to the presence of coronary stenoses (54 (15)% in those with coronary stenoses and 62 (16)% in those without, p < 0.05). CONCLUSION: The results demonstrate that significant stenoses in arteries supplying the non-infarct territory adversely affect global and regional left ventricular function after a transmural infarction. Non-infarct artery anatomy should be considered in intervention strategies to improve left ventricular function after acute myocardial infarction.

Importance of metabolic inhibition and cellular pH in mediating preconditioning contractile and metabolic effects in rat hearts.

The pathophysiological mechanisms by which brief periods of flow interruption before a prolonged ischemic period, ischemic preconditioning (IPC), increase myocardial tolerance to ischemia and improve myocardial function during reperfusion are not completely understood. To test whether short periods of metabolic inhibition in the absence of a flow reduction induce similar protective effects, we studied cardiac function and metabolism using 31P nuclear magnetic resonance spectroscopy in isolated isovolumic rat hearts. Fifteen hearts underwent IPC, consisting of two 5-minute ischemia-reperfusion cycles (IPC group); 18 hearts underwent brief metabolic inhibition by exposure to two 5-minute infusions of 10 mmol/L sodium cyanide (CN group); and 15 hearts served as controls. Subsequently all hearts were subjected to 30 minutes of total global ischemia at 37 degrees C followed by reperfusion. At the end of the ischemic period, creatine phosphate and ATP levels did not differ among the groups. Cellular pH, however, plateaued at a higher level in the CN group (6.51 +/- 0.03) and IPC group (6.12 +/- 0.06) than in the control group (5.84 +/- 0.01, P < .001). IPC and CN hearts had better functional and metabolic recovery than the control hearts. Improved contractile recovery correlated with coronary flow rates at reperfusion (r = .7, P < .001) and with pHi values at 30 minutes of ischemia (r = .8, P < .001) but not with increased ATP levels during ischemia. Additional control hearts were reperfused at 15 mL/min so as to match the flow rates of IPC and CN groups, but this did not result in improved performance. To test the hypothesis that the preconditioning effect was related to pHi during ischemia, additional IPC and CN hearts underwent the same preconditioning protocol, except that the cellular pH at the end of the ischemic period was lowered by the use of hypercarbic superfusion during ischemia or by the use of bicarbonate-free perfusate just before sustained ischemia. Both of these interventions resulted in significantly lower contractile and metabolic recoveries than those observed in other IPC and CN hearts. Therefore, the preconditioning effect does not require reduced coronary flow but can be effectively elicited by metabolic inhibition per se in this model. The protective effect is not dependent on preservation of global myocardial energy stores but, rather, on reduced acidosis during the prolonged ischemic period.