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Biomedical subjects

T P Graham

Publications and source records attributed to T P Graham.

At least 91 records · Page 5Linked to original sources
PubMed1982

Radionuclide evaluation of right and left ventricular function in children: validation of methodology.

Validation of an equilibrium radionuclide technique for assessing right and left ventricle function has not been reported in children with heart disease. Resting equilibrium radionuclide ventriculograms were performed in 71 children with diverse types of heart disease (age range 1 to 19 years, mean 10.2) with exercise studies in 52 of the children. Cardiac catheterization was performed in 39 of the 71 children within 2 weeks of radionuclide study. Resting left and right ventricular ejection fractions from radionuclide study and catheterization were compared by linear regression analysis: right ventricular ejection fraction, r = 0.83; left ventricular ejection fraction, r = 0.90. Interobserver correlations for right and left ventricular ejection fractions were 0.93 and 0.94, respectively. With exercise, the interobserver correlations for right and left ventricle were 0.97 and 0.92, respectively. Thus, right and left ventricular ejection fractions showed good correlations with cineangiographic ejection fractions. Furthermore, it was possible to perform this study in exercising children with no deterioration in interobserver correlations. This technique can provide important information on ventricular function in children and aid in long-term evaluation of current methods of treatment for several congenital heart defects.

Adolescent↗
PubMed1982

Retrograde cardiovascular angiography in infants, using a 3.6 French catheter.

Diagnostic retrograde arterial catheterization in infants, and small children has been constrained by the risk of arterial thrombosis and the low flow rate of catheters less than #5 French. We performed retrograde arterial catheterization (percutaneous technique in 21 of 24 patients) on 24 infants and small children (median age 3 months, median weight 4.1 kg), using a 3.6 French performed polyethylene catheter. Systemic heparinization was used. Among the group, we performed 23 aortograms, and 4 selective injections into a bronchial artery; all angiograms were of diagnostic quality. Injection rates ranged from 3 cc/sec to 10 cc/sec (median 5 cc/sec) with a peak developed pressure of 300 PSI to 900 PSI (median 700 PSI). No catheter-related complications were encountered during the study. Four of 24 patients developed a decreased pulse, noted immediately following the catheterization; however, pulses returned to normal within 24 hours, and late blood pressure assessment revealed no abnormalities in the catheterized leg. We now recommend this catheter for infants less than 10 kg when the following angiograms are required: 1. retrograde aortography (truncus arteriosus, pulmonary atresia, aortic stenosis, coarctation, coronary anomalies) 2. selective injections of bronchial arteries 3. retrograde catheterization of surgical shunts.

Angiography↗
PubMed1982

Myocardial injury in infants with congenital heart disease: evaluation by creatine kinase MB isoenzyme analysis.

Total creatine kinase (CK) and the myocardial isoenzyme CK MB activity were prospectively determined in 282 children hospitalized for cardiac catheterization and evaluation for suspected congenital cardiac abnormalities and compared with a hospitalized control group of children without such abnormalities. The percent CK MB and CK MB activity were abnormally elevated in symptomatic children with a large left to right shunt due either to a large ventricular septal defect (n = 22; p less than 0.001) or to complete atrioventricular canal (n = 10; p less than 0.001). Serum CK MB activity and percent CK MB were significantly related to the size of the shunt and the age of presentation with clinical symptoms of congestive heart failure in infants with a ventricular septal defect. CK MB activity was abnormally elevated in infants with symptomatic coarctation of the aorta, either with or without a ventricular septal defect (n = 15; p less than 0.001), and in infants with symptomatic aortic stenosis (n = 4; p less than 0.02). In contrast, CK MB activity was normal in asymptomatic children with coarctation of the aorta (n = 14) or aortic stenosis (n = 8) despite comparable systolic pressure gradients. CK MB activity and percent CK MB were abnormally elevated in those children with the cyanotic congenital cardiac abnormalities of either transposition of the great arteries (n = 32; p less than 0.001) or right ventricular outflow tract obstruction (n = 31; p less than 0.001). These results suggest that children with congenital cardiac abnormalities may have significant myocardial cell injury and release of CK MB that may be detected by the determination of serum CK MB activity. Cell injury may be secondary to arterial desaturation or acute pressure-volume overload, or both, as manifested by clinical symptoms of heart failure and measured hemodynamic variables.

Aortic Coarctation↗
PubMed1982

Ventricular performance in adults after operation for congenital heart disease.

Symptomatic ventricular dysfunction in adults who have had reparative operations for the more common congenital heart defects is uncommon. However, both invasive and noninvasive laboratory assessments of ventricular function have revealed abnormalities in some subsets of patients after repair of atrial septal defect, ventricular septal defect, aortic or pulmonary stenosis, tetralogy of Fallot, transposition of the great arteries and tricuspid atresia. Possible causative factors of late ventricular dysfunction after repair include the duration and severity of volume or pressure overload; the duration and severity of cyanosis; intermittent episodes of imbalance between myocardial oxygen supply and demand; residuae, sequelae and complications of treatment; and acquired disease. Further long-term follow-up studies are needed to assess the effect of current methods of therapy as well as timing of operative intervention on ventricular function in adults.

Adult↗
PubMed1982

Functional significance of reduced cardiac sympathetic innervation in the newborn dog.

The functional significance of anatomically reduced cardiac sympathetic innervation in the newborn is not known. This problem was investigated by examining ventricular contractile responses to repeated maximal left stellate ganglion stimulation in adrenalectomized and sham-adrenalectomized newborn (4-12 days of age) and adult dogs. At the end of five periods (5 min/period) of stimulation, sham-adrenalectomized puppies were still able to augment left ventricular force 13.0 +/- 3.8% (mean +/- SE; P less than 0.05) above control values. However, adrenalectomized puppies did not maintain their ability to enhance left ventricular force after the first period of stimulation. Similar results were obtained with measurements of the first time derivative of left ventricular force (dF/dt), right ventricular force, right ventricular dF/dt, and peak left ventricular pressure. Adult dogs were able to augment these measurements of cardiac function significantly throughout five stimulation periods whether or not their adrenal glands were intact. After five stimulation periods, adrenalectomized newborn dogs responded to isoproterenol, indicating that their cardiac beta-adrenergic receptors remained functional. We conclude that the known sparse ventricular sympathetic innervation in the newborn dog is associated with inability to maintain significant cardiac functional responses after repeated sympathetic stimulation and that adrenal integrity is required in the newborn to maintain appropriate ventricular responses to sympathetic stimulation.

Adrenalectomy↗
PubMed1982

Hypertrophic cardiomyopathy in infants: clinical features and natural history.

The clinical and morphologic features of hypertrophic cardiomyopathy in 20 patients recognized as having cardiac disease in the first year of life are described. Fourteen of these 20 infants were initially suspected of having heart disease solely because a heart murmur was identified. However, the infants showed a variety of clinical findings, including signs of marked congestive heart failure (in the presence of non-dilated ventricular cavities and normal or increased left ventricular contractility) and substantial cardiac enlargement on chest radiograph. Other findings were markedly different from those usually present in older children and adults with hypertrophic cardiomyopathy (e.g., right ventricular hypertrophy on the ECG and cyanosis). Consequently, in 14 infants, the initial clinical diagnosis was congenital cardiac malformation other than hypertrophic cardiomyopathy. Twelve of the 14 infants who underwent left-heart catheterization showed substantial obstruction to left ventricular outflow (peak systolic pressure gradient greater than or equal to 35 mm Hg). However, unlike older patients with hypertrophic cardiomyopathy, infants with this condition commonly had marked obstruction to right ventricular outflow (35-106 mm Hg) (nine patients); in six patients, the magnitude of obstruction to right ventricular outflow was at least as great as that to left ventricular outflow. Asymmetric hypertrophy of the ventricular septum relative to the left ventricular free wall was present in the 16 patients who had echocardiographic or necropsy examination. Ventricular septal thickening was substantial in patients studied both before and after 6 months of age (mean 16 mm), indicating that in patients with hypertrophic cardiomyopathy, marked left ventricular hypertrophy may be present early in life and is probably congenital. The clinical course was variable in these patients, but the onset of marked congestive heart failure in the first year of life appeared to be an unfavorable prognostic sign; nine of the 11 infants with congestive heart failure died within the first year of life. In infants with hypertrophic cardiomyopathy, unlike older children and adults with this condition, sudden death was less common (two patients) than death due to progressive congestive heart failure.

Angiocardiography↗
PubMed1982

Radionuclide ventriculography for assessment of absolute right and left ventricular volumes in children.

We determined absolute right and left ventricular volumes and cardiac output from the equilibrium radionuclide angiogram in 26 children, ages 3 months to 18 years, with diverse types of heart disease. We validated these results by comparing them with left ventricular (20 patients) and right ventricular (16 patients) cineangiographic volumes and cardiac output. Radionuclide volumes and cardiac outputs were determined in two ways: by a geometric method (area-length for left ventricle, Simpson's rule for right ventricle) and by a count-based method (correcting ventricular regional counts for frame duration, acquisition time, venous blood counts and attenuation). Both methods for estimating left ventricular end-diastolic volume compared favorably with cineangiography (correlation coefficients greater than 0.90). The count-based method also correlated well for the right ventricle. End-systolic measurements were not possible. Count-based assessment of cardiac output also correlated well with cineangiographic values. We conclude that right and left ventricular volumes and cardiac output can be reliably measured in children with equilibrium radionuclide ventriculography.

Adolescent↗
PubMed1982

Repair of atrioventricular canal malformation in the first year of life.

Disappointing results with pulmonary artery banding and subsequent correction led to the decision in 1977 that all infants presenting to our hospital with atrioventricular (AV) canal and evidence of severe heart failure, lack of growth, or pulmonary hypertension should have early operative correction. Since that time 24 consecutive infants have undergone repair. All had refractory heart failure. Average age at operation was 18 weeks (3 to 38) and average weight was 4.3 kg (2.3 to 6.4). Only four patients were older than 6 months of age at operation. Preoperative peak pulmonary artery pressure was 81 +/- 3.3 mm Hg, which was equal to systemic arterial pressure in all cases. Mean pulmonary-to-systemic resistance ratio was 0.28 +/- 0.05. five patients had moderate mitral regurgitation and five had a ductus arteriosus. Three had significant associated malformations. Profound hypothermia and circulatory arrest were utilized in all patients. Common AV valve tissue was divided and valvular integrity was ensured by resuspension to a single Dacron patch which closed both the atrial and ventricular defects. Operative death occurred in two patients (8%) both with associated defects (one with total anomalous pulmonary venous connection and the other with coarctation). One late death occurred in a patient with associated partial anomalous pulmonary venous connection, and one patient has had a pacemaker implanted. Survivors have been followed for 7 to 60 months. All patients are growing at an increased rate postoperatively. All cardiac medications have been discontinued in 16 of 21 patients. Operative repair of complete atrioventricular canal can be performed in infancy with low operative and late death rates and will relieve signs and symptoms of heart failure and allow more normal growth and development. On the basis of this experience, it appears unnecessary to delay operative correction with the known increased risk of the development of pulmonary hypertension.

Blood Pressure↗
PubMed1981

Pharmacokinetics of indomethacin in the neonate. Relation of plasma indomethacin levels to response of the ductus arteriosus.

To identify factors affecting the efficacy of indomethacin in closing symptomatic patent ductus arteriosus (PDA), we studied the pharmacokinetics of intravenous indomethacin, 0.2 mg per kilogram of body weight, in 35 premature infants with symptomatic PDA. Most infants responded to indomethacin with ductus constriction. Indomethacin infusions that were ineffective (seven doses in six patients) were associated with significantly faster clearance, a shorter half-life, and lower plasma levels (p less than 0.05). Six infants had later reopening of the ductus. All six received indomethacin in the first postnatal week; they could not be distinguished from infants with permanent closure on the basis of indomethacin kinetics, but they were of low gestational age. There was a 20-fold variation in plasma indomethacin levels 24 hours after a dose. In view of this variation and the relation between plasma levels and ductus constriction, we suggest that measurement of the plasma indomethacin level could be of value in infants with no response to a first dose.

Ductus Arteriosus↗
PubMed1981

Comparative right and left ventricular volumes and pump function in the newborn lamb.

A quantitative cineangiographic method is presented for studying neonatal lamb ventricular volumes and pump function without thoracotomy or surgical instrumentation of the heart. When this method was employed in lambs with a mean age of 24.4 hours it was found that the right and left ventricular end-diastolic volumes, ejection fractions and systolic outputs did not differ significantly at this early postnatal time. Restudy of these lambs at a mean age of 15.6 days showed that right and left ventricular end-diastolic volumes, normalized for body weight, and ejection fractions had not changed significantly. Although systolic outputs decreased, the difference was not significant. Thus there is early postnatal equalization of left and right heart volumes, and deviations from this relation should suggest abnormal hemodynamic function.

Animals↗
PubMed1980

Left ventricular function in cyanotic congenital heart disease.

Left ventricular function was studied with quantitative biplane cineangiocardiography in 39 preoperative and 23 postoperative patients with cyanotic congenital heart disease. Diagnoses included pulmonary atresia or critical pulmonary stenosis with intact ventricular septum (group 1), tricuspid atresia (group 2) and pulmonary atresia with ventricular septal defect (group 3). Preoperative patients ranged in age from 1 day to 7 years and postoperative patients from 7 weeks to 23 years. Left ventricular end-diastolic volume was increased in preoperative patients in groups 1 and 2 (132 and 136 percent of normal, respectively) but was normal in patients in group 3. Left ventricular ejection fraction was decreased to a similar extent in preoperative groups 1 to 3: 0.54, 0.55 and 0.56, respectively. After a shunt procedure left ventricular end-diastolic volume increased to 228 and 266 percent of normal in groups 1 and 2, respectively, but remained within normal limits in group 3. Left ventricular ejection fraction was normal in postoperative group 1 patients, whose ages averaged 1.8 years, but remained decreased in group 2 and 3 patients, whose ages averaged 8.1 and 5.6 years, respectively. Duration of cyanosis and degree of left ventricular dilatation appear to be important variables in regard to pump function in patients with cyanotic congenital heart disease.

Adolescent↗
PubMed1980

Preoperative diagnosis and management of infants with critical congenital heart disease.

Operative repair with an associated low morbidity and mortality is available now for most infants with congenital cardiac defects. Precise preoperative diagnosis is an essential part of continuing attempts to lower the operative risk for these patients. In this review we cover major areas of concern in regard to preoperative diagnosis and management. Long-term follow-up studies with clinical, hemodynamic, electrophysiological, and exercise data are required to assess current diagnostic and therapeutic practices.

Aortic Coarctation↗
PubMed1980

Impedance cardiographic assessment of symptomatic patent ductus arteriosus.

A modified impedence cardiographic technique was developed using a tetrapolar apnea monitor and minicomputer system. Evaluation of this technique in premature infants with and without symptomatic patent ductus arteriosus indicates that the magnitude of the cardiac-related deflection in the impedance signal is useful in the assessment of ductus shunting. Since the infant under study is involved only by the attachment of two double electrodes to the thorax, continuous assessment of ductur shunting is possible without disturbing routine care.

Cardiography, Impedance↗