No abstract

Twenty-eight patients with isolated secundum atrial septal defects were examined with right and left heart catheterization and cardioangiography. The radiographically assessed pulmonary-systemic stroke volume ratios and the physiologically determined pulmonary-systemic flow ratios correlated well. However, some striking discrepancies were observed the possible causes of which are discussed.

Demarcating fixed points in cardiac ventricles in the dog by catheter placement of tantalum coils has been shown to provide an excellent physiologic model. A new method emplying direct ventricular puncture has been developed for implanting these markers. The method has several advantages over an earlier peripheral catheter technique. Apical approach allows easier screw placement near the aortic and pulmonary valves. Peripheral vessels are left intact and pressure monitoring as well as contrast medium injection can be performed through the same catheter.

The hypothesis that the normal distribution of relative heart volume in the neonatal period is a mixture of two different populations, with different means and variances, has been tested. The definition of the two populations was (i) normally patent ductus and (ii) closed ductus arteriosus. The assumed frequencies of the patency in different age-groups were taken from Gentile et coll. [5]. A material consisting of 100 neonates found to be normal has been analysed radiologically during the first 360 hours after birth. The results strongly supports the hypothesis and explains the large normal range of relative heart volume during the first 48 hours of life.

Functional myocardial changes which result from ischemia are typically local rather than total. For assessing such regional changes quantitatively, left ventricular angiography has been used. The ventricular image has been divided into several components which can be measured individually. In order to test the validity of such methods, left ventricles of 5 dogs were labeled with endocardial tantalum markers and the segmental myocardial motion was estimated using cineangiography. Variance analysis of beat to beat measurements of total ejection fractions was performed. Total ejection fraction demonstrated the least variation with an average 3.5 per cent, segmental myocardial shortening 15 and regional stroke volumes 13 to 18 per cent. Intermethodologic variation with different regional volume measurements was 11 to 13 per cent. Regional stroke volume calculations showed large methodologic variations in beat to beat analysis. Conclusions and clinical decisions based on such measurements should be drawn with caution.