M. Paul Capp

Atrial Pressure-Flow Dynamics in Atrial Septal Defects (Secundum Type)

This study was conducted to determine the instantaneous pressure-flow relationships across secundum atrial septal defects. Simultaneous right and left atrial pressures and the pressure difference (determined with an analog computer) were recorded with matched catheter systems. Biplane cineangiocardiography was used to evaluate the timing of the shunts in various phases of the cardiac cycle.These studies indicated that the major left-to-right shunt and pressure gradient occurred over an interval encompassing late ventricular systole and early diastole. Also, there was augmentation of the left-to-right shunt during atrial contraction. Minute right-to-left shunting and pressure gradients occurred at two times in the cardiac cycle: (1) with the onset of ventricular contraction; and (2) during early ventricular diastole (heart rate, 80 to 100 beats/min). Detection of systemic right-to-left shunts by dye curves was enhanced by relatively slow heart rates (prolonged diastasis) which allowed the shunted blood to flow into the left venrticle. The effects of respiration during phasic changes in intrathoracic pressure resulted in an increasing left-to-right gradient during periods of increasing intrathoracic pressure and a fall in the left-to-right gradient across the defect during periods of decreasing intrathoracic pressure.

Left Heart Volume and Mass Quantification in Children with Left Ventricular Pressure Overload

This investigation was designed to quantify left ventricular and left atrial volume, volume change, systolic output, and ventricular mass in 31 patients with isolated left ventricular pressure overload secondary to aortic stenosis (AS, n = 14) or coarctation of the aorta (n = 17). These parameters were compared with normal standards and with data from a group of nine patients with a combined pressure and volume overload due to aortic stenosis plus aortic or mitral insufficiency (AS + AI or MI). Volumes were calculated from biplane cineangiocardiograms exposed at 60 frames/sec. Left ventricular end-diastolic volume (LVEDV) was significantly lower than normal in patients with AS (57 ± 11 cc/m2), but was normal (73 ± 12 cc/m2) in patients with coarctation. An increase in the ejection fraction (LVEF) was found in both groups averaging 0.73 ± 0.12 in AS patients and 0.69 ± 0.09 in coarctation patients. Patients with AS + aortic or mitral insufficiency (AI or MI) showed elevated LVEDV (103 ± 29 cc/m2), but had a normal ejection fraction. The LV mass was significantly increased in all groups: normal, 82 ± 10 g/m2; AS, 126 ± 41 g/m2; coarctation, 130 ± 44 g/m2; and AS + AI or MI, 168 ± 42 g/m2. The left ventricular systolic index and left atrial maximal volume were both normal in patients with pure pressure overload but were significantly increased in patients with combined pressure and volume overload. The low LVEDV in patients with AS as well as the normal volume in patients with coarctation occurred in the presence of elevated LV end-diastolic pressure and indicates a decrease in LV diastolic distensibility in patients responding to an isolated LV pressure overload by significant muscular hypertrophy without dilatation.

The effect of corrective surgery on left heart volume and mass in children with ventricular septal defect

Abstract Quantitation of left ventricular and left atrial volume, left ventricular ejection fraction and muscle mass was performed in 23 patients an average of 2 years after successful closure of a ventricular septal defect. The results were contrasted with both preoperative and normal values. Left ventricular end-diastolic volume averaged 84 ± 3 cc/m 2 ( X ± SEM ) postoperatively and was significantly decreased (P

Intracardiac Pressure-Flow Dynamics in Isolated Ventricular Septal Defects

This study was conducted to determine the nature of intracardiac shunting in 50 patients between the ages of 3 and 15 years with isolated ventricular septal defects. Simultaneous right and left ventricular pressures and biplane cineangiocardiography were utilized to study the timing and the direction of flow across the defect. Patients with low to moderately elevated right ventricular pressures demonstrated left-to-right shunting across the defect throughout the cardiac cycle. When pressure in the right ventricle approximated that of the left, right-to-left shunting occurred across the defect into the left ventricle during isovolumic relaxation. All patients shared in common the following: (1) a predominant left-to-right gradient and shunt across the defect into the body of the right ventricle during diastole; and, (2) augmentation of the left-to-right gradient with resultant increase of the shunt into the right ventricle during isovolumic contraction immediately preceding opening of the aortic valve.In comparing patients with and without pulmonary hypertension, the major variations in the cardiac cycle occurred during the periods of ventricular ejection and isovolumic relaxation. These two periods are primarily affected by the changing relationships of the size of the defect, ratio of pulmonary to systemic resistance, and magnitude of net shunts.

LIGHT AND ELECTRON MICROSCOPIC EXAMINATION OF THE SMALL BOWEL OF CHILDREN WITH CYSTIC FIBROSIS.

Peroral small bowel biopsies were performed on 21 children with cystic fibrosis and the tissue was examined by light and electron microscopy. Sections stained with hematoxylin and eosin appeared normal to light microscopy. However, periodic acid—Schiff stains showed a thickened mucinous cover in those patients with abnormal absorption. Electron microscopic examination was normal except for a coarse fibrillar substance, probably mucus, which appeared in the biopsy specimens from patients who had steatorrhea but was absent in the one patient without steatorrhea and in normal patients. This pathologic substance may contribute to the absorptive defect seen in patients with cystic fibrosis.

Effect of Site of Shunt on Left Heart-Volume Characteristics in Children with Ventricular Septal Defect and Patent Ductus Arteriosus

Quantitative cineangiocardiographic technics have been utilized to determine left ventricular (LV) and left atrial (LA) volumes and LV muscle mass in 58 patients with isolated ventricular septal defect, 14 of whom were infants less than 2 years old, and in 25 patients with isolated patent ductus arteriosus, 13 of whom were infants. Patients were divided according to the degree of left-to-right shunt into small (<35%), moderate (35 to 50%), and large (>50%) shunt groups. Data obtained in both the VSD and the PDA groups were compared with normal values. Left ventricular end-diastolic volume and mass and LA maximal volumes in the patients of both groups who had shunts of 35% or more were greater than normal and showed a linear increase with increasing left-to-right shunt. The LV ejection fraction was decreased from normal in infants with either VSD or PDA and a shunt of more than 50%. This variable was normal in older children with either VSD or PDA.Patients with an aortic or a ventricular defect and equivalent shunts did not differ significantly in terms of LV end-diastolic volume, LV mass, LV ejected fraction, or LA maximal volume, normalized for body surface area. Patients with a patent ductus demonstrated the following differences when compared with patients with ventricular septal defect: (1) elevated LV end-diastolic pressure, (2) elevated LV end-diastolic stress, and (3) elevated value for LV mass (/m2 BSA) per degree of shunt in children over 2 years of age with a patent ductus (P<0.05). These results indicate that left ventricular distensibility is decreased in patients with aortic left-to-right shunts compared to that in patients with ventricular left-to-right shunts of equivalent magnitude.

The Development Of A Digital Video Subtraction System For Intravenous Angiography

A system is under development for a relatively non-invasive technique for the assessment of atherosclerosis. The principle of this method is digital video x-ray subtraction for the visualization of arterial structures after the intravenous injection of contrast media. The prototype unit for the development of video subtraction techniques has been assembled and preliminary testing has started. Re-sults so far in dogs have shown good visualization of the heart, carotid arteries and renal arteries.

Ventricular Pressure-Flow Dynamics in Tetralogy of Fallot

The present study was conducted to determine the instantaneous pressure-flow relationships across the ventricular septal defect in tetralogy of Fallot. Simultaneous right and left ventricular pressures and the pressure gradient were recorded with matched catheter systems. Biplane cineangiocardiography was used to evaluate the timing of the bi-directional shunts during various phases of the cardiac cycle. The instantaneous pressure differences between the two ventricles and the direction of the pressure gradient correlated well with the timing of the shunt across the defect.In 27 patients with moderate tetralogy of Fallot, a consistent pattern of bidirectional shunting was shown. The right-to-left shunt occurred at two places and two sites during the cardiac cycle; namely, during early ventricular ejection into the aorta, and during isovolumic ventricular relaxation directly across the ventricular defect into the left ventricle. Left-to-right gradients and shunting across the defect were found to occur during isovolumic ventricular contraction and during diastole. The results of this study suggest that further investigation of various cardiac defects may yield important information concerning shunting mechanisms.

Photoelectronic Imaging for Radiology

This paper describes efforts to replace screen-film applications in radiology by an assemblage of x-ray intensifiers, video cameras, displays, and nonfilm storage media, the stimulus for which is twofold: economic and/or improved diagnostic performance. It is quite surprising to find that considerable financial benefit can occur by replacing film with a host of photoelectronic and electronic devices. This is due largely to the cost of a sheet of film being associated with each exposure, whereas photoelectronic devices provide one or thousands of exposures at essentially the same cost. It is not surprising to find, however, that the video output from a photoelectronic system can be readily digitized and made available for the benefits of image processing. This leads to rapid and convenient image acquisition and processing. The radiologist then has the benefit of an interactive display and can diagnose in a manner similar to that managed with the CT scanner. Heretofore, practice required reading out the film-based radiograph with a microdensitometer, followed by digitizing, processing, and producing processed radiographs. This technique is expensive and cumbersome. It was unable to stimulate the radiologist into being a routine user of processed radiographs. This paper examines the x-ray photon diagnostic image for its pertinent characteristics. It follows a review of current image acquisition components, i.e., screens, intensifiers, video tubes, and coupling optics. The purpose is to demonstrate an ability to acquire and transmit diagnostic x-ray images without significant degradation.

Heavy Ion Radiography

Heavy ion radiography is a new experimental form of medical imaging. The Lawrence Berkeley Radiation Laboratory is the only facility in the world with enough flux of heavy ions to satisfactorily visualize objects. A. model is described showing the superiority of heavy ion radiography, in regard to density resolution, compared to diagnostic x-ray energies and computerized tomography. Examples are shown. Tissue specimens are used for heavy ion radiography and the superior density resolution is demonstrated. Heavy ions are also being used for radiation therapy and early work on reconstruction is currently being done.