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Biomedical subjects

D A Fyfe

Publications and source records attributed to D A Fyfe.

At least 55 records · Page 3Linked to original sources
PubMed1989

Advances in the treatment of supraventricular tachycardia.

Patients with supraventricular tachycardia should be able to lead a perfectly normal life without significant treatment related side effects. Many of these patients have normal hearts and no other significant medical problems. Using the techniques described above, no patient should have significant symptoms from SVT.

Anti-Arrhythmia Agents↗
PubMed1988

Cardiomyopathy with arrhythmias and ectodermal dysplasia: a previously unreported association.

Hidrotic ectodermal dysplasia represents a group of congenital or hereditary disorders that involve ectodermal derivatives. It is characterized by partial or complete alopecia, dystrophic nails, and dental abnormalities. Dilated cardiomyopathy has not previously been reported in association with this illness. We report the cases of three children with fatal dilated cardiomyopathy with associated cardiac arrhythmias and ectodermal dysplasia. Laboratory investigations revealed no specific cause for the cardiomyopathy. It is speculated that this association is not simply coincidental.

Arrhythmias, Cardiac↗
PubMed1988

Valve prostheses in children: a reassessment of anticoagulation.

We have previously published evidence that children with St. Jude Medical prostheses on the left side of the heart may not require anticoagulation. Between March 1979 and September 1986, we followed up 48 patients who had no anticoagulant therapy for up to 7 years after valve replacement, an aggregate of 122 patient-years. The 25 male and 23 female patients ranged in age at implantation from 5 months to 21 years (12 +/- 6 years, mean +/- standard deviation). Five patients (all with complex associated malformation) died in the hospital (10%), and nine died late (22%). None of the early and one of the late deaths was associated with a thrombosed prosthesis. During follow-up, seven thrombotic (one mitral, one aortic) or thromboembolic (two mitral, three aortic) events occurred (5.7 +/- 2.1 per 100 patient-years). Of these seven events, five occurred within the last 14 months of the study. There was no relation of these events to age of patient at implantation, age at the time of even, gender, or site of implantation. Concurrently, we have followed up 340 adult patients with St. Jude Medical prostheses who had warfarin sodium (Coumadin) anticoagulation for 875 patient-years. By the end of this study, the children who did not receive anticoagulants were significantly less free of thrombotic and thromboembolic events than the adults who did receive anticoagulants (p less than 0.01).

Anticoagulants↗
PubMed1987

Double-chambered right ventricle.

Thirty (10.8%) of 279 patients undergoing correction of a ventricular septal defect (VSD) from January, 1972, to September, 1986, also had a double-chambered right ventricle (DCRV). Age at operation ranged from 1.3 to 18.8 years (mean, 6.7 +/- 4.5 years [+/- standard deviation]). Seventeen patients were male, and 13 were female. Two-dimensional echocardiography was used after 1978 in the initial evaluation of 20 patients; however, the diagnosis of DCRV was made with the use of subcostal views only since 1984 in 4 of 5 patients. Surgical correction consisted of closure of the VSD and resection of anomalous muscle bundles through a right ventriculotomy (28 patients), and right atriotomy (2 patients). All patients survived and are asymptomatic 4.2 +/- 3.4 years following operation. Six patients have undergone catheterization postoperatively and 8 patients had intraoperative pressure recordings. The mean preoperative ratio of right ventricular to left ventricular pressures was 0.67 +/- 0.22 compared with 0.34 +/- 0.15 postoperatively (p less than .001). In 2 patients, DCRV was not recognized preoperatively or at VSD closure through a right atriotomy, and reoperation was necessary after DCRV was demonstrated at postoperative catheterization. DCRV may occur in approximately 10% of patients undergoing correction of VSD. Careful evaluation of echocardiographic and catheterization data preoperatively and careful evaluation of the anatomy intraoperatively are necessary so that DCRV not be overlooked, especially because most VSDs are now closed through the right atrium. Successful correction of VSD and DCRV is associated with excellent long-term results.

Adolescent↗
PubMed1987

Resolution of dilated cardiomyopathy after surgical ablation of ventricular tachycardia in a child.

Sustained tachycardia may be associated with dilated cardiomyopathy that may improve after medical management of the tachycardia. Ventricular tachycardia due to an ectopic focus is uncommon in children and rarely presents as congestive heart failure. This report documents that severe dilated cardiomyopathy in a child was caused by sustained ventricular tachycardia and that, after cryoablation of the tachycardia focus, ventricular function rapidly returned to normal.

Cardiomyopathy, Dilated↗
PubMed1986

Further studies on the effect of chloroquine on the uptake, metabolism and intracellular translocation of [35S]cystine in cystinotic fibroblasts.

The present study uses the lysosomotropic drug chloroquine to investigate the mechanisms by which exogenous [35S]cystine is able to label the intracellular (intralysosomal) cystine pool(s) in cystinotic fibroblasts. When cystinotic fibroblasts were labelled for short periods of time (8 h or less), chloroquine (20 microM) inhibited the labelling of the intracellular cystine pool(s). However, when the cells were labelled for longer periods of time (24 h or more) chloroquine stimulated the labelling of the intracellular cystine pool(s). The short-term effect was selectively abolished when the cells were washed free of chloroquine, while the long-term effect was selectively abolished when the medium was depleted of cystine. Two routes of translocation of exogenous cystine to the lysosomes could be defined. One route was fast, had a low capacity, was inhibited by chloroquine and increased with increasing medium pH, while the other route was slow, had a high capacity, was stimulated by chloroquine and was more active at low pH. The former pathway probably consisted of plasma membrane transport of cystine into the cytosol followed by direct or indirect transport into the lysosomes. The latter route possibly consisted of pinocytosis with fusion of the cystine-containing pinosomes with lysosomes.

Biological Transport↗
PubMed1986

Myocardial ischemia in patients with pulmonary atresia and intact ventricular septum.

Children who die after operation for pulmonary atresia and intact ventricular septum may have myocardial ischemia. The relation between histologic evidence of myocardial ischemic injury and the presence of a right ventricle to coronary artery fistula, coronary artery dysplasia and operation in 17 autopsy specimens was assessed. Age at death ranged from 1 day to 16 years (median, 11 days). Of the 17 hearts, 6 (35%) had right ventricle to coronary artery fistulas, 5 of which had coronary artery dysplasia. In three cases, there was segmental or complete absence of a coronary artery. Ischemia was present in four of these six hearts, two of which had right ventricular outflow reconstruction. Six of the 11 hearts without right ventricle to coronary artery fistulas also had myocardial ischemia. Of these six cases, four had right ventricular outflow reconstruction and two had shunt operations. Death occurred from 1 to 8 days (mean 3) after operation. Hearts with pulmonary atresia and intact ventricular septum may have myocardial ischemia with or without either right ventricle to coronary artery fistulas or coronary artery dysplasia. Myocardial ischemia may occur after right ventricular outflow reconstruction or shunt operations. Thus, myocardial ischemia occurs commonly in patients with pulmonary atresia and intact ventricular septum and is not always related to coronary abnormalities or operation.

Adolescent↗
PubMed1986

Instantaneous pressure gradient: a simultaneous Doppler and dual catheter correlative study.

To more precisely measure the beat to beat and instantaneous pressure gradients across outflow stenotic lesions, simultaneous Doppler and dual catheter pressure gradient measurements were performed in 95 patients (mean age 42 years, range 1.5 to 85). There were 38 right ventricular and 62 left ventricular outflow obstructive lesions. Forty-nine patients also had a nonsimultaneous Doppler study performed within 7 days before catheterization. The simultaneous pressure waveforms and Doppler spectral velocity profiles were digitized at 10 ms intervals deriving maximal, mean and instantaneous gradients (mm Hg). For simultaneous maximal Doppler and catheter gradient measurements, the correlation coefficient (r) was 0.95 (SEE = 10 mm Hg), for Doppler and catheter mean gradients it was 0.94 (SEE = 8 mm Hg) and for maximal Doppler and peak to peak catheter gradients it was 0.92 (SEE = 13 mm Hg). The correlation of maximal and mean Doppler gradients with the respective catheter gradients was similarly high when the right and left ventricular outflow lesions were analyzed separately. However, the maximal Doppler gradient was significantly higher than the peak to peak catheter gradient. This was more evident with left ventricular outflow stenotic lesions. The correlation of the outpatient maximal Doppler and catheter gradients (r = 0.80, SEE = 17 mm Hg) was significantly lower than the simultaneous correlation (r = 0.96, SEE = 10 mm Hg) in the 49 patients with two Doppler studies. Continuous wave Doppler echocardiography accurately measures the instantaneous pressure gradient across both left and right ventricular outflow obstructive lesions. The maximal Doppler gradient should not be equated with the peak to peak catheter gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Truncus arteriosus with single pulmonary artery: influence of pulmonary vascular obstructive disease on early and late operative results.

Nineteen patients with truncus arteriosus and single pulmonary artery had corrective operations at the Mayo Clinic from 1969 to 1983. At operation, their ages ranged from 4 months to 20 years (mean 8.1 years). The preoperative pulmonary resistance divided by 2 was used to predict the degree of pulmonary vascular obstructive disease at operation. The influence of elevated pulmonary resistance and the intraoperative postrepair ratio of pulmonary artery to left ventricular pressure on operative and late mortality were examined. The outcome of patients with single pulmonary artery was compared with the outcome of 148 patients with truncus arteriosus and two pulmonary arteries operated on during the same period. Patients with a single pulmonary artery had an operative mortality similar to that of patients with two pulmonary arteries (32 versus 28%, p greater than 0.05). Late mortality was, however, significantly greater (p less than 0.001) for patients with a single pulmonary artery. Elevated ratios of intraoperative postrepair pulmonary artery to left ventricular pressure were associated with significantly higher (p less than 0.02) operative and late mortality, but elevated preoperative pulmonary resistance was not (p greater than 0.10). Truncus arteriosus with single pulmonary artery is associated with poor postoperative survival, and although elevated pulmonary resistances preoperatively did not predict outcome, elevated intraoperative postrepair pulmonary artery to left ventricular pressure ratios were associated with increased operative and late survival, suggesting a deleterious role of pulmonary hypertension.

Adolescent↗
PubMed1985

Continuous wave Doppler determination of right ventricular pressure: a simultaneous Doppler-catheterization study in 127 patients.

Simultaneous continuous wave Doppler echocardiography and right-sided cardiac pressure measurements were performed during cardiac catheterization in 127 patients. Tricuspid regurgitation was detected by the Doppler method in 117 patients and was of adequate quality to analyze in 111 patients. Maximal systolic pressure gradient between the right ventricle and right atrium was 11 to 136 mm Hg (mean 53 +/- 29) and simultaneously measured Doppler gradient was 9 to 127 mm Hg (mean 49 +/- 26); for these two measurements, r = 0.96 and SEE = 7 mm Hg. Right ventricular systolic pressure was estimated by three methods from the Doppler gradient. These were 1) Doppler gradient + mean jugular venous pressure; 2) using a regression equation derived from the first 63 patients (Group 1); and 3) Doppler gradient + 10. These methods were tested on the remaining 48 patients with Doppler-analyzable tricuspid regurgitation (Group 2). The correlation between Doppler-estimated and catheter-measured right ventricular systolic pressure was similar using all three methods; however, the regression equation produced a significantly better estimate (p less than 0.05). Use of continuous wave Doppler blood flow velocity of tricuspid regurgitation permitted determination of the systolic pressure gradient across the tricuspid valve and the right ventricular systolic pressure. This noninvasive technique yielded information comparable with that obtained at catheterization. Approximately 80% of patients with increased and 57% with normal right ventricular pressure had analyzable Doppler tricuspid regurgitant velocities that could be used to accurately predict right ventricular systolic pressure.

Adolescent↗