[Measurement of cardiac enzymes and infarct size].
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Biomedical subjects
Publications and source records attributed to G Menegatti.
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To define the optimal diagnostic strategy for acute myocardial infarction, 225 patients with suspected myocardial infarction were studied by serial (3 hour intervals) sampling for CK and CK-MB enzyme activity. In 12 patients the diagnosis of myocardial infarction was rejected. In the remaining 213 the myocardial infarction was transmural in 183 (anterior in 79, postero-inferior in 95, anterior and inferior in 9), non transmural in 30. In these patients the mean increase of enzyme activity, the time to pick activity and the infarct size (Sobel method) were measured. The best diagnostic sensitivity in the early phases of myocardial infarction was obtained by the combined use of CK and CK-MB determinations (95.9% of the diagnosis at 9 hours after the acute event). However the percent of positivity of CK & CK-MB values occurred significantly (p less than 0.01) later in non transmural (4.3% at 3, 34.7% at 6 and 86.9% at 9 hours after the onset of the chest pain) than in transmural myocardial infarction (25.2% at 3, 54.4% at 6 and 97.6% at 9 hours) and among these in inferior as compared to anterior (18.7% vs 32.2% at 3 hours, 46.8% vs 62.7% at 6 hours and 96.8% vs 98.3% at 9 hours). The CK/CK-MB ratio was of limited diagnostic value because it was increased (greater than 8) in most of the patients, either with normal or abnormal enzymes activities. Early kinetics differed in the different anatomo-clinical types of infarction. In all locations of myocardial infarction the mean enzyme activity increase was significantly correlated with the calculated enzymatic infarct size.(ABSTRACT TRUNCATED AT 250 WORDS)
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This study was carried out on patients of a coronary unit to evaluate the diagnostic efficiency of total CPK and CPK-MB by using different analytical techniques: catalytic, immunoassisted, cellulose acetate electrophoresis, radioimmunoassay and immunoradiometric assay. The behaviour of the enzyme was studied in all patients with reference to the localization and extent of the infarct. In all cases a diagnostic algorithm was followed based on the combined use of CPK and its MB isoenzyme; the activity was measured twice, at three-hour intervals after admission. In this way the utilization of total CPK and MB isoenzyme allows almost complete diagnostic efficiency within the first 9 hours from onset of chest pain, together with the possibility of calculating the slope of the curve of MB isoenzyme release useful for calculating infarct size. Maximum diagnostic efficiency is also obtained in cases of small infarcts, with silent ECG, and those difficult to classify clinically.
The feasibility and safety of percutaneous versus intra-aortic balloon pumping (IABP) in the elderly were evaluated in 45 patients who were over 65 years of age (range 65-79). All the patients required counterpulsation for complicated acute myocardial infarction. IABP insertion was attempted by the surgical technique in 22 patients, while the percutaneous approach was performed in 23. A consistent improvement in the incidence rate of successful insertion was attained with the use of the percutaneous technique as compared with the surgical one (91.3% v 59.1%, P is less than 0.05). Furthermore, no major complication was observed with the percutaneous catheter, while a 9.1% (2/22) incidence rate of serious complications was reported with the surgical technique. Thus, percutaneous IABP substantially decreased the unsuccessful insertions and the risk of severe complications in old patients, despite presumably severe aorto-iliac disease. No specifically age-related technical problem seems, therefore, to limit the applicability of intra-aortic counterpulsation to elderly patients, when percutaneous IABP is employed.
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The effects of the association of Isosorbide Dinitrate (ISDN) and Intra-Aortic Balloon Counterpulsation (IABCP) on ECGphic signs (in 24-lead precordial maps) of myocardial damage were studied in 7 patients (pts) with anterior acute myocardial infarction (AMI) without cardiogenic shock and/or pulmonary congestion, admitted to the CCU within 6 hours (hrs) since the chest pain. Matched control group consisted of 7 pts treated with ISDN alone. Analysis of variance showed that the association of IABCP and ISDN influenced favourably (p less than 0.01) the trend of the sigma ST (in all leads and in those with ST segment elevation greater than 0.2 mV), of the ST and of NST. The trend of sigma R was similar in the two groups. sigma Q was influenced either by time and by therapy; NQ was significantly lower (p less than 0.01) in pts treated with ISDN and IABCP. These findings seem to give evidence that the association of ISDN and IABCP may really be effective in reducing and stabilizing the ECG extent of ischemic myocardial injury in pts with transmural AMI without left ventricular failure; however this aggressive therapy cannot have a widespread indication until more reliable criteria for evaluating infarct size are available and larger randomized clinical trials performed.
In spite of great technological improvement in Ambulatory ECG Monitoring (AEM), there is still debate about its reliability in detecting ECG signs of myocardial ischemia and about the utility of AEM and Exercise Stress Testing (ET)--apart and/or in association--to predict Coronary Artery Disease (CAD). 50 consecutive male patients (pts) (mean age 51 +/- 69 years, 37 to 64 years) were studied for precordial chest pain. 17 had evidence of previous myocardial infarction. Resting ECG was normal in 21 pts and abnormal in 29; no pt received therapy during the examination period. ECG recordings were considered positive for ischemic ECG changes if there was greater than or equal to 1 mm of horizontal or down sloping ST-segment depression or ST-segment elevation of the same degree for greater than or equal to 0.08 sec in at least 15 consecutive beats; coronary arteriography was considered positive for significant CAD if any major vessel had greater than or equal to 75% luminal diameter narrowing. The percentage of false negative results was similar in AEM and ET (22.7% vs 22.2%); the false positives were few with both tests: 2 pts and 1 pt respectively; Bayesian probability (post-test likelihood for disease) calculated using the prevalence of CAD estimated from 2124 male pts who underwent coronary angiography in our Laboratory, for a given test result was very high: 97.1% +/- 1.3% (AEM), 98.6% +/- 1.1% (ET) and 98.1% +/- 1.1% (AEM & ET if concordant); post-test likelihood for CAD in a patient who did not show the given test result decreased to 67.8% +/- 1.3% (AEM), 60.9% +/- 1.1% (ET) and 52.1% +/- 1.1% (AEM & ET if concordant). The application of Bayes' theorem to these two non invasive tests improves the evaluation of patients with suspected CAD; the association of AEM and ET enhances the diagnostic accuracy.
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95 angina patients surgically treated by aortocoronary saphenous vein by-pass, have been studied by comparing the factors limiting the exercise (i.e. muscular exhaustion, angina, electrocardiographic changes), the total work performed, the O2 consumption and the heart rate-arterial pression product. After surgery the incidence of positive effort tests (effort angina and/or ecg evidence of myocardial ischemia) decreased from 79% to 27,4% (p less than 0,001), and the average amount of work performed increased from 2718 to 3504 Kgm (p less than 0,01), the MVO2 from 13,9 to 15,6 cc/min/Kg. (p less than 0,01) and the heart rate-arterial pression product from 206 to 243 (p less than 0,001). The patients who preoperatively were more invalidated (that is able to performe a lasser amount of physical work) presented a more pronounced improvement in comparison with those who had a greater tolerance to exercise. It seems therefore that for these latter patients the bypass grafting surgery should be justified only if a significant increase of life expectancy and reduction of myocardial infarction incidence could be definitely proved. The exercise performance improvement after surgery was statistically significant only in the patients with post infarction or with unstable angina not in those with chronic angina. The perioperative infarction (present in 8,4% of cases) did not show any unfavorable correlation with the result of the late postoperative effort test.
110 male subjects, under 60, admitted for myocardial infarction in 1980 and 1981, have been considered. 85 answers to the questionnaire, sent by post have been obtained, 6 pertaining to patients who died in the meanwhile. Among the 79 living patients who replied, 57 (72.1%) had resumed work within the average time of 4.8 months (min. 0.5-max. 12). Return to work has been significantly higher among self-employed people than employees; only 15 subjects had changed job or task. The subjective rating of the actual health status, two years after the infarction, has been satisfactory in 90.5% of cases, in spite of 56.5% complaining of heartburn, 38.1% of dyspnea and 35.7% of palpitation. The work-load has been rated as tiring only by 12.6% of them, while 65.6% have maintained unchanged their work capacity. Electrocardiographic monitoring (by the Holter method), during a normal workday, showed no significant differences between working and retired subjects and, also, in work and normal activity periods. 19 subjects (47.5%) presented ventricular arrhythmias, in 12 cases at high risk, most of them being unaware of it. These arrhythmias were more frequent during wake periods, but not strictly connected to the type and the quality of the work activity. The patients subjected to rehabilitation showed no differences in the cardiovascular patterns during the ergometric test and ECG monitoring when compared to those not subjected to rehabilitation.
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