A routine method for diagnosis of early myocardial infarction

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Brief Reports A routine method for diagnosis of early myocardial infarction * Jose Milei and Narciso J. Bolomo Patho1og.v Section, Hospital Institute of Cardiology, National Academy of Medicine, Cnel. Diaz 2423, Buenos Aires, Argentina (Received

12 January

1983; revision received

1 June 1983; accepted 2 June 1983)

We compared Barbeito-Lopez Trichrome stain with H-E, the basic fuchsin picric acid and Nitro Blue of Tetrazolium stains. The Bark&o-Lopez Trichrome stain was much more sensitive than the other stains for the diagnosis of early myocardial coagulation necrosis. In the course of studies of isoproterenol-induced cardiac lesions in rats [l], we have noticed that myocardial necrosis was clearly delineated by Barbeito-Lopez Trichrome stain [2] and decided to carry out a systematic evaluation of it. Pathological material Forty Wistar rats were injected intraperitoneally with isoproterenol sulphate 10 mg/kg, and killed after 30 min and 24 hr. Histological stains, histochemical methods for succinic dehydrogenase and conventional ultrastructural studies were used. Forty hearts with early myocardial infarcts (3 to 48 hr) were studied, To delineate accurately the area of the infarct, Nitroblue of Tetrazolium stain was used. Macrosections were stained with the aforementioned histological stains. Definitions We defined early coagulation necrosis as patchy cytoplasmic alterations in a single fiber with minor nuclear changes. The cytoplasmic changes consist of patchy homogenization, with relative loss of cross striations or increased granularity, thinning and waviness of fibers or hypereosinophilia. It included “contraction bands” [4]. Established coagulation necrosis was defined as homogenization of the cytoplasm and progressive nuclear lysis, visible on H-E sections (Fig. 1). The Barbeito-Lopez Trichrome stains normal myofibers green, whereas those myofibers showing coagulation necrosis shift to a golden yellow color. Observations In animals killed at 30 min myocardial damage was characterized by subendocardial fibrillar homogenization (Fig. 2) and CB. The latter were clearly shown by the Barbeito-Lopez Trichrome and the basic fuchsin-picric acid stains but only rarely by H-E. In animals killed

* This study was supported

International

with a grant

from Fundacion

Journal of Cardiology, 4 ( 1983) 3 19-32 B.V.

0 Elsevier Science Publishers

1

H. Pombo

de Rodriguez.

Fig. 1. Transmural infarction: serial sections. Bottom: established coagulation necrosis; A, the fibers are stained golden yellow by the Barbeito-Lopez Trichrome stain: 8, hypereosinophilia with H-E. Top: progressive myocytolysis of several myofibers corresponding to the 3- or 4-cell layers of subendocardium. The relatively preserved myofibers are stained green with the Barbeito-Lopez Trichrome stain (between arrows) (x 250). Human transmural infarct, 2 days old.

at 24 hr sections revealed focal established coagulation necrosis, homogenization and contraction bands. Early and established coagulation necrosis was clearly shown by the Barbeito-Lopez and basic fuchsin-picric acid methods. Ultrastructural findings confirmed the histological and histochemical data. In human material a close correlation existed between the Nitroblue of Tetrazolium and Barbeito-Lopez Trichrome stain. The former showed areas of early coagulation necrosis which were not visualized with H-E but grossly pointed out with Nitroblue of Tetrazolium stain. Differences between values of this stain and microscopical mapping with Barbeito-Lopez Trichrome stain were always < 10%. The Barbeito-Lopez Trichrome stain was highly reliable for alteration of early coagulation necrosis. It appears as patchy yellow areas while the remainder of the cytoplasm stains green. Contraction bands were also stained yellow and were more frequently demonstrated than with H-E. A simple control was used to certify the reliability of the stain. In human infarcts the 3- or 4-cell thick layers of muscle just beneath the endocardium are always spared because these cells receive their oxygen from the ventricular lumen or the Thebesian vessels or are Purkinje cells. These cells were preserved and the deeper ones were necrotic and stained yellow with the Barbeito-Lopez Trichrome stain (Fig. 1). Results obtained with this stain may be due to

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Fig. 2. Subendocardial cytoplasm homogenization is clearly shown by the Barbeito-Lopez Trichrome and the basic fuchsin-picric acid but imprecised by H-E. Serial sections. A, H-E; B, basic fuchsin-picric acid; C, Barbeito-Lopez Trichrome stain (X 250). Experimental material. Myocardium of rat injected with isoproterenol and sacrificed after 30 min.

diminution of intracellular pH and membrane different elements as occurs in early myocardial

permeability injury [5].

alterations

with penetration

of

References 1 Milei J, Rapaport M. Localization by autoradiography of triated isoproterenol in “infarct-like” lesions of rat myocardium. Am Heart J 1976;92:351-355. 2 Barbeito-Lopez JA, New trichrome stain. Am J Clin Pathol Technol 1946;16:53-56. 3 Nachlas MM, Shnitka TK. Macroscopic identification of early myocardial infarcts by alterations in dehydrogenase activity. Am J Pathol 1963;42:379-397. 4 Fishbein MC, Meerbaum S, Rit J, et al. Early phase acute myocardial infarct size quantification: validation of the triphenyl tetrazolium chloride tissue 1981;101:593-600. 5 Musy JP, Haag JR. Diagnostic de n&roses myocardiques Ann Anat Pathol 1977;22:97- 116.

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