[Tomographic studies of myocardial perfusion normality with 99m Tc-Tetrofosmin. Spanish multicenter study]. / Estudios tomográficos de normalidad de perfusión miocárdica con 99mTc-Tetrofosmina. Estudio multicéntrico español (I). Aspectos técnicos: diseño del estudio y control de calidad.

As a first phase in a nationwide multicenter study to obtain myocardial perfusion normality patterns, this work presents the study design and quality control methodology used to guarantee that the gammacameras fulfilled some minimum quality requirements. The following aspects were considered in the study design in order to guarantee the homogeneity and interchangeability of the results: creation and structure of the work group, data interchange system, data selection and acquisition, centralized archiving and processing, assessment system, study acceptance criteria and distribution of the results. To carry out the instrumental quality control, three phantom studies were established, one to control the rotation center, another to verify tomographic uniformity and a third to simulate the shape and orientation of the left ventricle. The three phantoms circulated through all of the 18 participating centers in this project, which corresponded to 19 gammacameras. Very strict guidelines had to be followed in the acquisition and processing of these phantom studies. If any camera and/or center did not fulfill the criteria established, it was advised of the problem detected in order to correct it. Once the defect was repaired, all the phantoms were sent again for verification. Uniformity of the rotation center was quantified by means of the eccentricity of a 360 degrees orbit, admitting up to a maximum of 10%. Tomographic uniformity was visually assessed, taking in account the number of slices with rings and their contrast and finally no artifacts could be present in the reconstructed study of the ventricle. The center of rotation was within limits in all the cameras except one case while the tomographic uniformity was incorrect in 6 cases. All the departments, except one, corrected the defects detected, and passed the acceptance test. The results made it possible to guarantee adequate homogeneity and instrumental quality in this multicenter study.

[Tomographic studies of myocardial perfusion normality with 99m Tc-Tetrofosmin. Spanish multicenter study]. / Estudios tomográficos de normalidad de perfusión miocárdica con 99mTc-Tetrofosmina. Estudio multicéntrico español (II). Aspectos clínicos.

This objective of this study was to obtain a pool of Myocardial Perfusion SPECTs with a 99mTetrofosmin stress/rest one day protocol in normal volunteers having a less than or equal to 5% likelihood of coronary artery disease that represents normalcy in the Spanish population. A total of 169 volunteers from 15 hospitals were studied. The volunteers were divided into 5 groups: Groups 1, 2 or 3 corresponding to men < 30 years (n = 33), men between 30 and 50 years (n = 32), or men > 50 years (n = 31); Groups 4 or 5: premenopausal (n = 38) or postmenopausal women (n = 35). A clinical history, physical examination, clinical laboratory parameters, echocardiography and a symptom limited exercise stress test were performed in all of them and had to be normal. The mean likelihood of coronary artery disease was 1.15 +/- 1.07%.Twenty-four segments were analyzed in each study and were classified into 5 grades of uptake (1 = normal, 2, 3, 4 = mild, moderate or severe defect and 5 = no uptake). Defects were then analyzed according to sex and location. Considering the stress and rest studies separately (8,112 segments), only 19 moderate and 75 mild defects were found, these corresponding to 16 volunteers, with more inferior defects in men and anterior defects in women. These data validate the normalcy of our population. A pool of Myocardial Perfusion SPECTs with a 99mTetrofosmin stress/rest one day protocol in normal volunteers that represents Spanish normal values was obtained.

Stunned myocardium and cellular damage in patients undergoing valvular cardiac surgery and pretreated with captopril.

BACKGROUND: Following extracorporeal cardiac surgery, transient myocardial dysfunction (stunning) and cellular damage may develop in relation, among other mechanisms, to the production of free radicals (FR) during reperfusion. The purpose of this study is to evaluate whether captopril (CTP), an angiotensin converting enzyme inhibitor with a thiolic group, which has been shown to be useful as an antioxidant agent both in in vitro and in vivo studies, can prevent emergence of those problems when used as pretreatment within 24 hours in patients undergoing valvular cardiac surgery. EXPERIMENTAL DESIGN: prospective and randomized study. Comparison of data pre-ischemic (pre-aortic clamping) and post-reperfusion (post-cardiac rewarming) was performed. Ejection fraction was compared pre-surgery, after surgery and after 3 months. SETTING: cardiology and cardiovascular surgery services in a general hospital. PATIENTS OR PARTICIPANTS: thirty patients who had to undergo valvular replacement surgery were randomly allocated to two similar groups, one group pretreated with captopril (CTP group, n = 15) and the other group without it (CON group, n = 15). Exclusion criteria (left ventricular ejection fraction <40%, evidence of angiographic coronary disease or prior myocardial infarction and peroperative myocardial infarction). INTERVENTION: in CTP group, the dose of captopril administered was 12.5 mg every 8 hours orally, from 24 hours before. MEASURES: using electron microscopy of myocardial biopsies taken prior to aortic clamping and post-reperfusion, a semi-quantitative analysis was performed on the degree of myocytic damage (MD), mitochondrial swelling (MS), sarcoplasmic reticulum swelling (SRS) and content in glycogen granules (GLY). Left ventricular ejection fraction was evaluated isotopically at three timepoints, preoperatively (EF1), at 2-3 days (EF2) and at 3 months (EF3). Also, analytical data were collected from the coronary sinus to determine creatine phosphokinase (CPK) and activity of the angiotensin converting enzyme (ACE). RESULTS: We noted that, in general, cellular damage resulting from valvular surgery is low, the degree of MS and SRS being lower in the CTP group. In the CTP group, however, there is a stunning phenomenon (EF1: 54.9+/-6.9%; EF2: 50.8+/-8.5%; EF3: 57.7+/-7.7%) which does not occur in the CON group (EF1: 58.0+/-8.3%; EF2: 60.8+/-10.9%; EF3: 63.0+/-9.3%). CONCLUSIONS: We conclude that the cellular damage caused during valvular replacement surgery is small, and emphasize that pretreatment with CTP further minimizes both MS and SRS; however, for reasons as yet unknown, CTP pretreatment may induce myocardial stunning, an indication that at these low rates of cellular damage, CTP has no beneficial effect, either because it is ineffective as an antioxidant agent or because FR formation has little repercussion in human beings, pointing out to the likely existence of other mechanisms that may induce an appearance of postsurgical myocardial stunning.