Myocardial hydroxyproline reduced by early administration of methylprednisolone or ibuprofen to rabbits with radiation-induced heart disease.

The ability of methylprednisolone (MP) and ibuprofen (IB) to reduce the severity of the late state of radiation-induced heart disease was assessed in 57 New Zealand white rabbits. Before and shortly after cardiac irradiation, 15 rabbits received i.v. MP, 30 mg/kg twice daily for 3 days, and 15 others received IB, 12.5 mg/kg twice daily for 2 days. No drug was administered to 14 irradiated rabbits, and neither irradiation nor drugs were administered to 13 rabbits that served as controls, All 15 rabbits treated with MP and 13 of the 15 treated with IB lived for 100 days. Only seven of the untreated, irradiated rabbits lived that long. Longevity of each treated group of rabbits was better (p less than 0.01 and 0.05) than that of the untreated, irradiated rabbits. Surviving rabbits were killed 100 days after irradiation. Pericarditis (p less than 0.05) and pericardial effusion (p less than 0.01) were less frequent in the treated, irradiated groups than in the untreated, irradiated rabbits. At least some rabbits in each irradiated group had microscopic evidence of myocardial fibrosis. The fibrosis was quantitated by determination of myocardial hydroxyproline concentrations (MHP). MHP concentration in the untreated, irradiated rabbits was greater than in those treated with MP (p less than 0.05) or IB (p less than 0.01) and in the untreated, unirradiated rabbits (p less than 0.01). Early administration of MP or IB retarded the development of myocardial fibrosis, pericarditis and pericardial effusion, and improved survival in this experimental model of radiation-induced heart disease.

Detection of tricuspid regurgitation and estimation of central venous pressure by two-dimensional contrast echocardiography of the right superior hepatic vein.

Two-dimensional echocardiography (2DE) was utilized to visualize the right superior hepatic vein (RSHV) for detection of tricuspid regurgitation (TR) and estimation of central venous pressure (CVP). Patients were divided into two groups. Eighteen patients were placed in group I on the basis of typical clinical features of TR (five patients) or 2DE contrast evidence of TR (13 patients). Group II included 55 patients without TR. Maximal transverse dimension of RSHV of at least 1.8 cm (range 1.8 to 3.8 cm, mean 2.4 cm) identified all patients in group I (100% sensitivity). One patient in Group II had RSHV width of 2.1 cm (96% specificity). Predictive value was 95%. RSHV width ranged from 0.4 to 2.1 cm (mean 1.3 cm) in group II. Mean values for group I and II were significantly different (p less than 0.001). Linear regression analysis was utilized to compare CVP and maximal RSHV width in 42 patients (15 group I and 27 group II). The slope of the line was significantly different from zero (p less than 0.005); the correlation coefficient was 0.70. In patients with maximal RSHV width greater than 1.5 cm, the predictive value for elevated CVP (greater than 6 mm Hg) was 87% with 69% sensitivity and 78% specificity. In 13 group II patients with technically satisfactory 2DE but no distinctly visible RSHV, CVP ranged from 4 to 12 mm Hg with four elevated values (greater than 6 mm Hg). Predictive value of normal CVP in absence of visible RSHV was 69%. This study suggests that determination of maximal RSHV width is useful in detection of TR and may be helpful in estimation of CVP.

Two-dimensional echocardiographic assessment of electrocardiographic criteria for right atrial enlargement.

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.

Radionuclide imaging of experimental myocarditis.

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 99mTc. Histologic examination of all 23 hearts revealed qualitatively similar, typical lesions of myocarditis. This study suggests that cardiac imaging with 67Ga may be useful in the detection of myocarditis.

Effect of bile acids on electrical properties of rat colon: evaluation of an in-vitro model for secretion.

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.