Right atrial (RA) size was determined with two-dimensional echocardiography using the apical four-chamber view in 45 adult patients with various echocardiographic criteria for RA enlargement and in 25 normal controls. RA size varied from 11.4-24.0 cm2 (mean 16.1 cm2) in controls. RA enlargement (greater than or equal to 25 cm2) was found in only two of 11 patients with P pulmonale (predictive value [PV] = 18%) and one of five with prominent positive P-wave forces in lead V1 (PV = 20%). However, RA enlargement ws found in eight of eight patients with a qR pattern in lead V1 in the absence of clinical indications of coronary artery disease (PV = 100%). RA enlargement was also found in 13 of 28 patients with a total QRS amplitude in lead V1 of 6 mm or less and a threefold or greater ratio of total QRS amplitude in lead V2 relative to that in V1(V2/V1 greater than or equal to 3) (PV = 48%). A V2/V1 ratio of 4 or more detected 11 of 13 patients with RA enlargement, with six false-positive diagnoses (sensitivity = 85%, specificity = 60%, PV = 65%). The combination of total QRS amplitude in V1 of 4 mm or less, together with a V2/V1 ratio of 5 or more, detected six of 11 with RA enlargement, with one false-positive diagnosis (sensitivity = 46%, specificity = 93%, PV = 86%). We conclude that ECG criteria for RA enlargement that primarily use increased P-wave amplitude have a limited PV. The qR pattern in lead V1 appears to be extremely accurate in detecting RA enlargement. ECG criteria in leads V1 and V2 using decreased amplitude in leads V1 and a V2/V1 greater than or equal to 3 are of some value in detecting RA enlargement.

SUMMARY A preparation of rat colon mucosa has been evaluated as a useful model to study effects of bile acids on the changes in short-circuit current and transmural electrical potential difference (pd) which others have associated with alterations in electrolyte transport. Using this preparation, it was found that bile acids were effective in increasing short-circuit current and pd when applied to the serosal, but not the mucosal, surface of the tissue. Furthermore, taurine-conjugated cholic acid, which has no demonstrable effect on the colon in vivo, was found to increase short-circuit current and pd significantly in the in-vitro preparation. These data indicate the limitations of the in-vitro model in studying the mechanism of bile acid-stimulated intestinal secretion.

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SUMMARY The ability of 67Ga citrate and 99mTc pyrophosphate cardiac imaging to detect myocarditis was assessed in an experimental rabbit model. Twenty-three rabbits were imaged approximately 72 hours after infusion of i.v. norepinephrine. Diffuse cardiac uptake was found in 13 of 15 rabbits scanned with 67Ga. Tissue distribution studies documented significant myocardial uptake of 67Ga in those with positive scans. Precordial imaging and tissue distribution studies revealed no cardiac uptake in the eight rabbits scanned with 9mTc. Histologic examination of all 23 hearts revealed qualitatively similar, typical lesions of myocarditis. This study suggests that cardiac imaging with 17Ga may be useful in the detection of myocarditis.MYOCARDITIS, an inflammatory condition involving the heart, can lead to sudden unexpected death or severe congestive heart failure.1'3 Yet, its accurate detection is frequently difficult." 8 The clinical manifestations are often nonspecific," 3 and conventional diagnostic tests such as the ECG, serum cardiac enzymes and chest x-ray are insensitive as well as nonspecific.", 3,4 Recently, a brief clinical report5 and two experimental studies6' 7 have suggested that radionuclide cardiac imaging can detect the presence of myocarditis. In this report, we present the results of radionuclide cardiac imaging with 99mTc pyrophosphate and 67Ga citrate in an experimental model of myocarditis. Methods and MaterialsMyocarditis was created in 23 adult New Zealand white rabbits using a modification of the technique of Downing and Lee.8 Each rabbit was anesthetized with i.v. pentobarbital (30 mg/kg) and a 25-gauge butterfly needle was secured in a marginal ear vein. Norepinephrine was infused at a rate of 3 ,tg/kg/min for 100 minutes using a Harvard constant infusion pump. Radionuclide Imaging with 67Ga CitrateMyocardial imaging was performed in 15 rabbits 70-74 hours after the norepinephrine infusion. Five normal control rabbits were also imaged. All rabbits received 1.3 mCi of 67Ga citrate through a marginal ear vein 24 hours before cardiac imaging.After i.v. pentobarbital anesthesia, the rabbits were immobilized in the supine position. A single 10°left anterior oblique image of the heart was obtained using From Upon completion of in vivo imaging, each animal was sacrificed with a lethal dose of i.v. pentobarbital. The heart was excised intact, washed free of blood and clot, and weighed. The excised hearts from 10 of the rabbits were imaged again. Twenty-five thousand counts were obtained in each image. In each rabbit, the radioactivity content of heart and thigh muscle was individually assayed in a Capintec dose calibrator. Background counts were recorded and net counts were expressed in gCi/g of tissue.Radionuclide Imaging with "mTc Pyrophosphate Cardiac scintigrams were performed on eight additional rabbits 70-74 hours after norepinephrine infusion. All rabbits received 5 mCi of 99mTc pyrophosphate via a marginal ear vein, and 2-3 hours later, a single 10°left anterior oblique image of the cardiac ...