Biomedical subjects
Publications and source records attributed to T P Graham.
Chages in external pH from 7.40 to 6.95 obtained by changing the pCO2 of the medium at constant bicarbonate concentration produced in cat papillary muscles a significant decrease in isometric tension with no changes in time to peak tension. Active and resting stiffness, as determined by two different methods, did not change under conditions of hypercapnic acidosis.
Right and left heart volumes, ejection fractions and ventricular outputs were determined from biplane cineangiocardiograms in infants with symptomatic coarctation of the aorta and correlated with clinical and hemodynamic alterations. Patients were divided into two age groups: group 1, aged 3.5 to 14 days and group 2, 5 weeks to 7 1/2 months. Infants in group 1 had severe depressions of left ventricular ejection fraction and output associated with normal left ventricular size. The massive cardiomegaly in these infants results from right heart enlargement secondary to left-to-right atrial shunting, and pulmonary hypertensive right heart failure, and possibly a more distensible right than left ventricle. Infants in group 2 also have right, and to a lesser degree, left heart enlargement. Group 2 patients differ from group 1 infants in having less impairment of left heart pump function and significant left ventricular myocardial hypertrophy. Echocardiographic measurements of left ventricular pump function are normal or increased in postoperative patients. Thus alterations of left ventricular function in infants with symptomatic coarctation appear to be largely afterload related and do not indicate permanent impairment of left ventricular contractile function.
Eighty-one patients with tetralogy of Fallot malformations evaluated between July 1, 1971 and November, 1975 are presented. Fifty-one patients underwent primary intracardiac repair; three died. Twenty-seven patients were corrected after a previous palliative shunt; there was one death. Three additional patients have been palliated and are awaiting repair. While the overall mortality in these patients was less than 5%, the infants undergoing total correction before the age of two years appeared to be at greater risk (25%). There were no deaths in the group of patients undergoing palliative procedures. Based on these data it appears that a safely performed palliative shunt in the symptomatic small infant is a reasonable first step, particularly if the outflow tract of the right ventricle is diffusely hypoplastic.
Left ventricular and left atrial volume, left ventricular ejection fraction, and left ventricular muscle mass were determined preoperatively and postoperatively in 13 patients who underwent surgical closure of ventricular septal defects in the first two years of life. Left ventricular end-diastolic volume and systolic output averaged 255 +/- 19% (+/- SEM) and 240 +/- 19% of normal, respectively, before operation but fell to within normal limits postoperatively. Left ventricular ejection fraction was normal preoperatively (100 +/- 4% of normal) and remained so after correction (106 +/- 3%, NS). Left ventricular mass was mildly elevated at the preoperative catheterization (271 +/- 21%) and decreased significantly following repair (P less than 0.001). However, the postoperative left atrial volume (147 +/- 14%) remained abnormal (P greater than 0.05). These data suggest that when early surgical closure of a ventricular septal defect is necessary because of failure of medical management, good results with regard to postoperative left ventricular size and function can be expected.
Right heart volume data were obtained in 63 patients with tetralogy of Fallot. The patients were divided into three groups: 1) preoperative tetralogy (N=34); 2) post shunt procedure (N=14); 3A) post repair without outflow patch (N=10); 3B) post repair with an outflow patch (N=8). In Group 1 right ventricular end-diastolic volume (RVEDV), RV ejection fraction (EF), and RV systolic output (SO) were all mildly depressed. In post shunt patients, RVEDV was normal but RVEF remained depressed. RVEDV and RVSO increased following a shunt procedure, and these variables were larger in patients with a large versus a small shunt. In Group 3A RVEDV, RVEF, and RVSO were normal. In contrast in patients in Group 3B, RVEDV was increased averaging 177 +/- 15% of normal RVEF was depressed averaging 0.45 +/- 0.04, and RVSO was normal. RV size and pump function are abnormal in patients whose operation requires an outflow tract patch and the factors which may contribute to these abnormalities include a higher RV peak pressure, pulmonary incompetence, and a larger noncontractile outflow tract. Longitudinal studies relating these variables to clinical performance and exercise testing will be important in assessment of the importance of these abnormalities.
Four cases of congenital tricuspid insufficiency (CTI) are presented in whom spontaneous improvement occured. There was no evidence of Ebstein's disease in three of the four. All presented with similar clinical and laboratory findings including massive cardiomegaly, mild to moderate congestive heart failure, and moderate to severe desaturation. Catheterization data demonstrated severe TI and right-to-left atrial shunting. During the period of follow-up, up to 3.5 years, all symptoms have spontaneously disappeared. Clinical and angiocardiographic evidence for minimal residual TI have remained. Right atrial and right ventricular volume measurements were markedly abnormal initially and returned to normal or near normal. These measurements may be a useful method for quantitating the severity of tricuspid insufficiency. The course of the three infants with massive CTI (without Ebstein's disease) differs from previous reports and may be important both in formulating future management plans and in defining the etiology of the disorder.
Right and left ventricular volume characteristics were determined from biplane cineangiocardiography in 37 patients with isolated ventricular septal defects. Patients were divided into three categories as determined by the degree of left-to-right shunt: small shunt-less than 35% of pulmonary blood flow (N=9); moderate shunt-35-49% (N=8), and large shunt-greater than 50% (N=20). Right ventricular (RV) end-diastolic volume was increased above normal in 15 of 20 studies performed in patients with large left-to-right shunts and averaged 159 +/- 10% of normal (P less than 0.001). In contrast, only one of the patients in the small shunt group and only half of the patients in the moderate shunt group showed increases in RV end-diastolic volume. The increase in RV volume was proportional to the corresponding increase in left ventricular end-diastolic volume, with the right ventricle ranging from 48 to 116% of LV end-diastolic volume (average 83%). Right ventricular ejection fraction was normal in all patient groups. Right ventricular outpur was increased commensurate with the increases in the RV end-diastolic volume. These data indicate that substantial augmentation in RV end-diastolic volume does occur in patients with isolated ventricular septal defects and large left-to-right shunts. These data can be explained by the significant diastolic and "isovolumic" shunting from left ventricle to right ventricle which occurs in these patients.
A 5-year-old boy had clinical, cardiac catheterization, and operative findings of a thoracic arteriovenous fistula arising from the right subclavian artery. The venous connection was to the paravertebral plexus with eventual drainage into the inferior vena cava through the right common iliac vein. To our knowledge, this type of fistula has not been reported previously and is believed to represent embryological defects of the first or second posterior intercostal arteries as well as maldevelopment of the venous connections of azygos vein to the superior vena cava, which resulted in the observed caudal venous pathways becoming operative.
Right and left heart volume data were obtained during 44 cardiac catheterizations in 24 patients with complete transposition of the great arteries (TGA) prior to "corrective surgery." Patients were divided into three hemodynamic groups: I)TGA with intact ventricular septum, N = 23 studies in 13 patients, ages 1 day-22 months; II)TGA with ventricular septal defect (VSD), N = 12 studies in six patients, ages 7 days-15 months; III)TGA with VSD plus pulmonary stenosis, N = 9 studies in five patients, ages 5 days-5.6 years. In group I, right ventricular end-diastolic volume (RVEDV) averaged 170 plus or minus 52% of normal (P smaller than 0.001), RV ejection fraction (EF) was 0.48 plus or minus 0.09, 74% of normal (P smaller than 0.001), and RV systolic output (SO) was 123 plus or minus 34% (NS). In group II, RVEDV was 163 plus or minus 25% of normal (P smaller than 0.001), RVEF 0.59 plus or minus 0.08, 91% of normal (NS), and RVSO was 158 plus or minus 52% (P smaller than 0.02). In group III, RVEDV averaged 124 plus or minus 26% of normal (P smaller than 0.04), RVEF 0.58 plus or minus 0.15, 89% of normal (NS), and RVSO 125 plus or minus 57% (NS). Right atrial maximal volume was increased in 21 or 22 studies and averaged 185 plus or minus 47% of normal (P smaller than 0.001). RVEDV was greater than left ventricular end-diastolic volume in all but one patient in group I, but RVEDV/LVEDV was smaller than 1.00 in four VSD patients with very large pulmonary flows. A majority of patients with TGA without VSD have abnormal right heart function as indicated by an increased RVEDV and a low ejection fraction. Longitudinal studies of right ventricular performance in these patients continue to be important in assessment of current methods of therapy.
Postoperative data were obtained at cardiac catheterization in twelve patients studied 6-29 months following Mustard's operation for transposition of the great arteries (TGA) to assess the incidence and severity of abnormalities of right ventricular (RV) function. Age at operation was 5-13 months in seven patients (infant group) and 19-25 months in the remaining five patients. RV end-diastolic volume (EDV) decreased in all patients following surgery and averaged 123% of normal in the postoperative group (NS). RV ejection fraction (EF) was depressed postoperatively averaging 0.45 (69% of normal (P less than 0.001) as was RV systolic output (78% of normal, P less than 0.01). LVEDV averaged 65% of normal (P less than 0.001), LVEF 0.67 (103% of normal, NS), and LV systolic output 67% of normal (P less than 0.001) following operation. Left atrial (systemic venous) volume was decreased in all postoperative patients averaging only 39% of normal (P less than 0.001). A high incidence (greater than 50%) of partial baffle obstruction was found and LV systolic output showed a significant negative correlation with baffle gradients. The low output postoperatively may be related to decreased LV filling pressure, a small LV reservoir, and thus a small atrial "booster pump." Pressure-velocity indices of RV contractile function in four patients showed a poor correlation with pump function. Long-term follow-up will be required to determine the clinical significance of the abnormalities of venous return and ventricular function.
The effect of a similar degree of "respiratory" and "metabolic" acidosis was studied in seven isolated in vitro human pectinate muscles and eight ventricular muscle bundles. Either "respiratory" or "metabolic" acidosis (from 7.36 plus or minus 0.03 to 7.01 plus or minus 0.02 and 6.98 plus or minus 0.03, respectively) depressed in vitro contractility in human atrial or ventricular muscle to a similar extent. Previous contradictory responses of myocardial tissue to alterations in pH appear to be the result of species differences.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.