K. Thygesen

Plasma enzymes in myocardial infarction. An appraisal of quantitative, clinical and pathophysiological information.

In twenty-nine patients suffering from acute myocardial infarction changes of concentrations in plasma of creatine kinase, aspartate aminotransferase and lactate dehydrogenase were monitored 1 week following onset of infarction. The temporal characteristics of enzyme changes described are (i) the time lag from onset of chest pain until increasing enzyme concentrations occur, (ii) the time of maximum concentrations, and (iii) the period during which enzyme is released into blood. Three estimates for the extent of the infarct (i) the peak value of the plasma enzyme curves,(ii the value of the cumulated plasma curves, and (iii) the size of the infarct in grams of necrotic myocardial tissue were, as expected, closely correlated. It is concluded, that the three types of quantification of infarct size are of almost identical value for clinical, prognostic usage, From a pathophysiological point of view they are of limited interest being based on assumptions that are either unlikely to occur or cannot be tested in man.

Variability of plasma proteins according to molecular size. Long-term and short-term intra-individual variation

The intra-individual variations in serum concentrations of alpha 1-antitrypsin, albumin and alpha 2-macroglobulin were determined using high precision analytical methods. The long-term (3 months) variations were 8.2% for alpha 1-antitrypsin and 2.9% for alpha 2-macroglobulin in five males and five females. The coefficients of variation for albumin were 1.5 and 3.4% for males and females, respectively. In males the long-term variations of albumin and alpha 2-macroglobulin were highly correlated. The short-term (2 days) intra-individual variations in six males were 2.5, 3.8 and 3.4% for alpha 1-antitrypsin, albumin and alpha 2-macroglobulin respectively (coefficients of variation). A diurnal variation was found for albumin with maximal concentrations at 18.00 hours. At 6.00 and 10.00 hours the fractional concentrations of alpha 1-antitrypsin and albumin were lower than for alpha 2-macroglobulin. The variations of the three proteins were positively correlated.

Creatine kinase and creatine kinase B-subunit in stable and unstable angina pectoris

Abstract. Repetitive ischaemic episodes may have a cumulative effect leading to irreversible myocardial cell damage with enzyme release. Using plasma creatine kinase (CK) and creatine kinase B‐subunit (CK‐B) concentrations this theory has been tested in forty‐eight patients admitted with acute chest pain, but without ECG signs of acute myocardial infarction (AMI). The patients were classified into four groups: Fourteen patients with non‐ischaemic heart disease (non‐IHD), seventeen with stable angina pectoris (SAP), ten with unstable angina pectoris (UAP), and seven patients who developd AMI during the study period. The enzyme variation in non‐IHD delineates the background noise, and the increased variability in AMI indicates the full scale of the enzyme signals in cases of irreversible cell damage. Patients with SAP have the same enzyme signal as the background noise in respect of both CK and CK‐B. However, in UAP the signal of CK‐B equals the background noise, whereas the CK signal is separated from the latter. The reason may be that the signal to noise ratio of CK‐B is poor and the analytical sensitivity low. Therefore, the behaviour of CK‐B in this study does not support the above theory although our findings for CK indicate that the consequence of repeated ischaemic attacks is slight enzyme release.

Plasma enzymes in myocardial infarction Application of a two-compartment model in assessing myocardial release of enzyme

The time dependent appearance (appearance function) of creatine kinase, aspartate aminotransferase and lactate dehydrogenase into plasma of 29 patients suffering from myocardial infarction has been calculated.The model for calculating the appearance function was based on the assumption of distribution of enzymes into two compartments, plasma and extra-vascular.The values of exchange rate constants for enzymes between the compartments were chosen on the basis of rate constants for proteins with molecular weights similar to the three enzymes.The order of magnitude of enzyme catabolism in each of the compartments was unknown. Assumptions of different ratios between catabolism in the two compartments led to highly significant changes in the appearance functions for the enzymes.Appearance functions for each patient of creatine kinase and aspartate aminotransferase showed almost identical patterns provided adequate catabolic constants were used, whereas the appearance function of lactate dehydrogenase differed ...

Praecordial ECG-mapping in acute anterior myocardial infarction: The variability of ST segment, Q and R waves

Praecordial ECG-mapping (forty-two unipolar leads) was carried out on sixteen patients with anterior acute myocardial infarction (AMI) and on ten control patients without AMI. The variability, chronometric changes and the error-of-measurement when measuring sigma ST, sigma Q and sigma R in an ECG-map were evaluated. The investigation demonstrated that there was a significant inter-individual variation of sigma ST, sigma Q and sigma R in both patient groups. In cases of AMI, the intra-individual variation of sigma St, sigma Q and sigma R was significantly greater than the variation in the error-of-measurement; this applied also to the control group, except for sigma ST which was of the same magnitude. Inducing measuring errors, which were brought about by changes in the position of the patient, were of the same magnitude as the itra-individual variation in the control group. The chronometric variation of sigma ST, sigma Q and sigma R were significant in the patients with AMI; this also applied to sigma ST in the control group, but not to sigma Q and sigma R. In patients with AMI, sigma ST and NST were correlated to heart rate, mean arterial blood pressure, the product of heart rate and systolic blood pressure, and respiratory rate. However, only the correlations between heart rate and sigma ST and NST, respectively, were of such a magnitude that they were of clinical relevance. Thus 37-42% of the variance in the ST segment within 14 days after the onset of the infarction can be explained by changes in the heart rate.