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Home , Chagas disease

Tc-99m PyrophosphateMyocardialScanningin Chagas'Disease

Antonio F. Gonçalvesda Rocha, Berdj A. Meguerian,and John C. Herbert

Hospital Beneficencia Portuguesa, , Brazil and Georgetown University Hospital, Washington, D.C.

Chagas' dIsease Is a serIous protozoan affecting up to 20 % of popula tionsIn some endemic areas. MyocardltIsand cardlomyopathyoccur in 50% of patientswhogoontodevelopchronicChagas'disease.Wehavestudieda patient withnoovertcardiacsymptomswhorevealedIntensemyocardialuptakeofTc 99m pyrophosphate.The signifIcanceof this findingin relationto early detection andprogressof therapyis explored.

J Nuci Med 22: 347—348,1981

Chagas' disease(South American ) is an in tration of pyrophosphateis found in severalconditions (lable 1) fection caused by cruzi. Ihe disease is transmitted (3). We haverecently studieda patient with Chagas'diseasewith by reduviid bugs, primarily thoseof the genera Triatoma, Pan intense myocardial uptake of pyrophosphate.To our knowledge strongylus, and Rhodnius, andoccursin a largeareafrom Mexico no previous cases have been reported. to Argentina, the main foci being in Argentina, Brazil, Chile, Uruguay, and Venezuela.In Brazil severalstatesare considered CASE REPORT endemicregions.It is estimatedthat 20%of peopleliving in these areasare infected,totalling nearly 4,000,000people.In the United A 48-year-oldmanfromthe state of MinasGeraisin central States,animal infestations havebeendetectedin wild rats, opos Brazil was referred for radionuclide bone scanning becauseof sums,and mice, but only a handful ofclinically apparent indige spinal pain with normal bone radiographs. Ihe total-body bone noushuman caseshavebeenreported from lexas. scanwasperformed using 20 mCi of Ic-99m stannouspyrophos Ihe bugs hide in the cracks and thatch of poorly constructed phate and a scintillation camera. No bony abnormalities were rural dwellings.They attack peopleat night, usuallybiting the face detected, but the showed4+ (greater than rib intensity) at the mucocutaneous junction (hence the common name “kissing―myocardial concentration (Fig. 1). The patient had no symptoms or “assassin―bug). Human infection results from contamination of cardiac diseaseand the ECG was normal. Becauseof the pa of the wound by the bug's feces,which contain the flagellated tient's origin, a serum complement-fixation test was performed trypanosomes. and wasfound positive for Chagas' disease. Ihe diseaseis manifestedby both acuteand chronic forms. The DISCUSSION form is initiated by the appearanceof trypanosomesin the generalcirculation. Ihis occursafter an incubationperiodof 2 wk, Ihe mechanismby which Ic-99m pyrophosphate,a bone during which the organismsmultiply within the chagoma at the seekingtracer, concentrateswithin damagedmyocardium is not site of the bite. This stage, which may range in intensity from subclinical to prostration, is characterized by recurrent fever, generalized , hepatosplenomegaly,urticarial rash,and acute . Ihe pathogenesisof thesesymptoms TABLE1. CONDITIONSASSOCIATEDWITH appears to be an autoimmune inflammatory reaction involving MYOCARDIALUPTAKEOF Tc-99m mesenchymal tissues. PYROPHOSPHATE The late manifestations are neuropathy causedby destruction of ganglionic nervecells,and diffuse myocarditis with associated I. pectoris , , and . 2. The useof radionuclidescanningtechniquesto studymyocardial 3. DC cardioversion diseasewasintroduced largely by Bonteet al. in 1974,using Ic 4. Malignant effusions 99m pyrophosphate for the diagnosis of 5. Myocardial infarction (1,2). Experience since then has shown that myocardial concen 6. Myocardialirradiation 7. ReceivedSept.23, 1980;revisionacceptedNov. 13,1980. 8.Trauma Forreprintscontact:JohnC. Harbert, MD, Div. of Nuclear Mcd 9. Ventricularaneurysm icine, Georgetown University Hospital, Washington, D.C. 20007.

Volume 22, Number 4 347 ROCHA, MEGUERIAN, AND HARBERT

noovertcardiac symptoms,suggestthat positivescan findingsmay precedeclinical manifestations. ThedetectionofchronicChagas'diseaseisaccomplishedwith substantial reliability by complement fixation (Machado-Guer reiro test) and tests (12). The diagnosis of functional cardiac abnormalities can be made by a variety of ra diographicand echographictechniques(13). Thesetests, however, donotrevealspecifictissueinjury,nordotheyindicatedisease activity. Pyrophosphatescanning,on the other hand, is known to outline specific regionsof myocardial necrosis(14), and scanin tensity may relate to the evolution oftissue injury and recovery (3). It is possible,then,that in Chagas'diseasemyocardialscanning may be useful in identifying not only the early presence of Chagas' myocarditis, but also its progresswith .

REFERENCES

1. BONTE FJ, PARKEY RW, GRAHAM KD, et al: A new method for radionuclide imaging of myocardial infarcts. Radiology110:473-474,1974 2. PARKEY RW, BONTEFJ, MEYER SL, et al: A new method for radionuclide imaging of acute myocardial infarction in FIG. 1. Anterior scintlphotoof thorax 2 hr after administrationof 20 humans. Circulation 50: 540-546, 1974 mCi Tc-99m stannouspyrophosphate.Arrow indicatesdiffuse, In 3. LYONs KP, OLsON HG, ARONOW WS: Pyrophosphate tense myocardlal uptake. myocardial imaging. Semin Nucl Med 10: 168-177, 1980 4. D'AGOSTINO AN, CHIGA M: Mitochondrial mineralization well understood. Becauseradiolabeled phosphatesare known to in human myocardium. Am I Clin Pathol 53: 820-824, concentrate in areas of high calcium turnover, calcium binding has 1970 been postulated as the mechanism. Electron micrography has 5. BUJA LM, PARKEYRW, DEESJH, et al: Morphologic cor shown that in irreversibly injured muscle cells calcium deposits relates of technetium-99m stannous pyrophosphate imaging within mitochondria in the form of apatite-like spiculesor asfine ofacute myocardial infarcts in dogs. Circulation 52: 596-607, granular particles (4—6).Direct binding of the phosphatemoiety I975 to the apatite structures may occur. 6. BUJA LM, DEEs JH, HARDING DF, et al: Analytical dec. Wrogamann and Pena have postulated a condition of mito tron microscopicstudy of mitochondrial inclusions in canine chondrialcalciumoverloadingasapathologicfeatureof all mus myocardial infarcts. I Histochem Cytochem 24: 508—516, dc-cell necrosis(7). Up to 50 times normal concentration of cal I 976 cium may be found in individual mitochondria. They suggestthat 7. WROGAMANN K, PENA SD: Mitochondrial calcium over such mitochondrial overload leadsto lossof cellular energy, hy load:A generalmechanismfor cell necrosisin musclediseases. percontractionof musclefibers,and cell necrosis.Buja et al. found Lancet 1: 672-674, 1976 elevatedcalcium in experimentalmyocardialinfarction and related 8. BUJA LM, PARKEY RW, STOKELY EJ, et al: Pathophysi theuptakeof pyrophosphateto this mechanism(8). ology of technetium-99m stannous pyrophosphate and Wehavefoundnohistochemicalstudiesconcerningmyocardial Thallium-201scintigraphyof canineacutemyocardialin calcium concentrationsin Chagas'disease,but the histopathologic farcts.Circulation52:11-51,1975 changes have been well described (9). Involved muscle cells are 9. IAFuRI WL: Fine structure of Chagas' diseaselesions. In diffusely distributed throughout the heart. Intracellularly there New Approaches in American Trypanosomiasis Research. is mitochondriosis, vacuolization, and increase of intramitochon PanAmericanHealthOrganization,Washington,D.C. Publ drial granules; lysisof myofibrils; rupture of the sarcoplasmicre No. 318,Mar, 1975,pp.152—161 ticulum; and protrusion and thickening of the sarcolemma.In the 10. ANSELMI A, PIFANOF, SUAREZJA, Ctal: Myocardiopathy interstitium, large numbers of lymphocytes, plasmacytes, and in Chagas' disease. 1. Comparative study of pathologic find histiocytes surround the infected cells. Ihe degree of fibrosis is ings in chronic and experimental Chagas' myocarditis. mt Rev related to the severity and duration of the disease. TropMed4:97, 1971 Ihe myocarditisof Chagas'diseaseis causedby direct myo I I. MARSDEN PD: South American trypanosomiasis (Chagas' cardial invasion of the trypanosomes, leishmanial multiplication, disease).mt Rev Trop Med 4: 97, 1971 and intracellular .When the pseudocystsrupture, re 12. SCHMUNIS GA, SZARFMAN A, COARASA L, et al: Anti leasingthe newly formed leishmanialand trypanosomalforms, an agglutinins in acute Chagas' disease. Am intense inflammatory responseresults (10,!!). In the untreated JTropMedHyg29: 170-178,1980 patient, the chronic nature of the myocarditis is ensured by re 13. PUIGBOJJ, VALECILLOS R, HIRSCHAULT E, et al: Diag peatedreleaseand invasionof the trypanosomes.Ihe importance nosis of Chagas' cardiomyopathy. Non-invasive techniques. of detecting myocardial involvement is underscoredby its high PostgradMedf53:527-532,1977 incidence in chronic Chagas' disease(as high as 50%of infected 14. ZARET BL, DICOLA VC, DONABEDIAN RK, et al: Dual individuals, and asmany as I0%of rural populations) and the se radionuclide study of myocardial infarction. Relationships rious disability and mortality that result if the disease is not between myocardial uptake of potassium-43, technetium-99m checked (10,11). Considerably more patients will need to be stannouspyrophosphate,regional myocardial blood flow and studied to determine the incidenceand variability ofscan findings creatine phosphokinasedepletion. Circulation 53: 422—428, in Chagas' disease. Those in the patient presented here, who had 1976

348 THE JOURNAL OF NUCLEAR MEDICINE