Microsphere trapping was determined in isolated perfused Langendorff hearts of cats and rabbits with 7.9-, 8.6-and 14.6-micrometers microspheres. Only the largest spheres were completely trapped whereas significant and relevant fractions of the smaller spheres were found in the perfusate leaving the heart. These fractions were 8.3 and 3.0% of the total activity for the cat and 6.7 and 2.1% for the rabbit hearts. The density of spheres trapped in the outer layer was similar with all three sizes of microspheres, whereas the density in the subendocardial layer increased with increasing microsphere size and paralleled overall trapping in both species. The complete trapping of 14.4-micrometer microspheres proves that there were no leaks and no arterio-venous shunts. The results obtained with the two smaller sphere sizes suggest regional differences in trapping and therefore regional differences in capillary size. Only selected batches of commercially available 7-10 micrometer spheres should be used. The mean diameter should be 10 micrometer with a standard deviation no larger than 1 micrometer. 15-micrometer spheres may not be ideal but, nevertheless, give reasonable values, for intramyocardial distribution of blood flow in cats and rabbits.

Animals↗

PubMedDate not supplied

Validation studies for the use of the microsphere method in cats and young minipigs.

Radioactive microspheres are suitable for measuring cardiac output, its distribution and organ blood flow if certain criteria are met. Cardiac output may be determined with the reference flow method if microspheres do not recirculate. In case 10 micron microspheres were extracted completely by the lungs. The use of microspheres for the determination of cardiac output is therefore not limited by recirculation of microspheres down to this size. Under baseline conditions we found no preferential streaming with 50 micron spheres in young minipigs and with 25 and 15 micron spheres in cats At high cardiac output values induced by the administration of 0.4 mg/kg of Dihydralazine in cats, 25 micron but not 15 micron microspheres showed a small, non significant tendency to stream preferentially into the upper body. Thus, under rapid flow conditions 15 micron microspheres may be preferable to larger ones from the rheological point of view. Under baseline conditions the distribution of cardiac output to a wide range of organs was very similar when comparing 25 and 15 micron microspheres in cats and 50 and 15 micron microspheres in minipigs, whereas 10 micron microspheres were poorly extracted by most organ in cats. 15 micron microspheres were found to be suitable for the determination of cardiac output and its distribution in both species provided that bronchial and arteriovenous shunt flows can be neglected.

Animals↗

PubMedDate not supplied

Complete atrioventricular septal defect and Ebstein anomaly.

The newborn reported here presented with congestive heart failure and cyanosis on the first day of life. Echocardiographic examination revealed complete atrioventricular septal defect and Ebstein anomaly, a rare combination that has not been previously reported in the literature.

Ebstein Anomaly↗