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Biomedical subjects

D J Vince

Publications and source records attributed to D J Vince.

At least 19 recordsLinked to original sources
PubMed1996

Dilatable prosthesis for banding the main pulmonary artery: human clinical trials.

The objectives of this trial are to assess the safety and effectiveness of the prosthesis and to establish the ability of the dilatable band to provide a nonsurgical option for dilatation. Forty-six patients received dilatable bands. All had congenital heart defects requiring banding of the main pulmonary artery. Dilatation was performed on 7 patients. This was successful in 6 and uncomplicated in all. In one patient the dilatable band was adjusted too tightly at implantation. In one patient the band was adjusted to loosely. In 7 patients the dilatable band was placed too distally and partially obstructed the right or left pulmonary artery. Distal migration of the dilatable band after implantation did not occur. One band was distorted during implantation. This did not compromise its function. Surgical sepsis resulted in a mycotic aneurysm and erosion of the pulmonary artery in one patient. Surgical pulmonary arterioplasty was performed in all 18 patients who had total correction and in 11 of the 13 patients who had bidirectional Glenn procedure and Damus-Stanzell connection. There were 13 deaths. None of the deaths were related to the dilatable band. Thirty-two prostheses were surgically explanted readily and completely in 31 patients. Five bands were removed at postmortem examination. Examination of all 37 of the dilatable bands revealed no evidence of wear or damage. Scanning electron microscopy evaluation was conducted on 5 of the explanted devices which had been implanted 158 to 1139 (mean 422) days. No component failure was identified. The dilatable band prostheses was effective and safe and provided a non-surgical option for dilatation.

Blood Vessel Prosthesis↗
PubMed1993

Antiplatelet therapy in children with left-sided mechanical prostheses.

Valve replacement in children has always been associated with a high mortality, outgrowth of the prosthetic valve and difficulty in managing anticoagulation. Between January 1985 and April 1991, 20 patients (14 males and 6 females) underwent replacement of a left-sided cardiac valve. The median age at diagnosis was 21.6 months (1 to 120 months) and the median age at surgery was 85 months (11 to 213 months). Six patients were under 4 years of age. The site of valve replacement was aortic in 11 patients and left atrioventricular (AV) valve in 9 patients. The indications for aortic valve replacement were stenosis (6) and incompetence (5). The left AV valve was replaced in three patients following repair of AV septal defect, in one patient with corrected transposition of the great arteries (LTGA), in one patient with severe dysplasia and insufficiency, and in four patients for congenital mitral stenosis. A Bjork-Shiley prosthesis was used in three mitral and one aortic position, all the other patients receiving a St. Jude prosthesis: six mitral and ten aortic. All patients were anticoagulated (warfarin) for 3 months post implantation and then switched to a regimen of aspirin and persantine. There was no early or late death. Median follow-up was 12.3 months (4 to 72 months). Total follow-up was 59 patient-years or 708 months. There was one incident of thromboembolism (1.7%/patient-year) and four instances of bleeding (6.8%/patient-year). There was no valve thrombosis. Our regime of early warfarin followed by long-term antiplatelet therapy has been associated with a low incidence of thromboembolism and no valve thrombosis.

Adolescent↗
PubMed1991

Human clinical trials of the dilatable pulmonary artery banding prosthesis.

OBJECTIVE: To test the hypothesis that the dilatable pulmonary artery banding prosthesis is as effective and safe to use as conventional fixed fabric bands, and provides an additional nonsurgical option for dilation. DESIGN: Nonrandomized prospective human clinical trial. SETTING: British Columbia's Children's Hospital for tertiary care. PATIENTS: All patients admitted with congenital heart defects who required banding of the pulmonary artery during a 17 month period. The patients who received a dilatable band were selected on the basis of their cardiologist's preference. INTERVENTIONS: Surgical banding was performed using accepted techniques. Intraluminal balloon dilation of the pulmonary artery band was done using techniques accepted for intraluminal balloon dilation in pulmonary valvuloplasty. MAIN RESULTS: Eleven patients received the dilatable bands and eight received fixed bands. There was no evidence of failure of the bands to maintain their function. One patient required intraluminal balloon dilation of the dilatable band. This was successfully accomplished without complication. The dilatable bands were easier to remove than the fixed bands, but required greater surgical dexterity to place and adjust. One of the dilatable bands was applied too distally and one too tightly. One fixed band was applied too tightly and another too loosely, requiring a second banding operation. CONCLUSIONS: The dilatable pulmonary artery banding prosthesis is as effective and safe to use as a fixed fabric band. It is easier to remove and provides a nonsurgical option for dilation.

Blood Vessel Prosthesis↗
PubMed1989

A prosthesis for banding the main pulmonary artery, capable of serial dilatation by balloon angioplasty.

A prosthesis constructed with a fatigued steel helix encased in a silicone rubber shield was used to band the main pulmonary artery in 10 dogs. After a mean duration of 138 days the banded site was dilated with a 20 mm diameter angioplasty catheter. This dilatation produced a mean increase of 44.3% in the cross-sectional area. A further mean increase of 2.2% in the cross-sectional area was measured 137 days after the dilatation. In five uncomplicated experiments a second dilatation was performed with a 23 mm diameter angioplasty catheter after a mean interval of 140 days. The second dilatation produced a further 21% increase in the cross-sectional area. In the five experiments in which two dilatations were performed, there was a total increase in the mean cross-sectional area of 94% produced 273 days after banding. This prosthesis maintains banding of the main pulmonary artery and can be serially dilated by balloon angioplasty.

Angioplasty, Balloon↗
PubMed1988

Cardiac output by MR imaging: an experimental study comparing right ventricle and left ventricle with thermodilution.

Cardiac output was measured by gated magnetic resonance imaging (MRI) and by thermodilution in four mongrel dogs. The entire heart was examined in contiguous slices at end-diastole and end-systole in a plane parallel to the interventricular septum. Each set of images was analyzed for chamber volume using a custom computer program to evaluate each pixel. No geometric assumptions were made. Cardiac output was calculated for right and left ventricles and compared with the thermodilution data. We found that the cardiac output of the right ventricle compared well with that of the left ventricle and that both fell within the range measured by thermodilution. Cardiac-gated MRI has the potential to assess the cardiac output of both the right and left ventricles. Comparison between right ventricular and left ventricular function will permit quantification of left to right shunting or unilateral ventricular volume overload.

Animals↗
PubMed1987

A protective device for pacemaker generators in children.

A protective device comprised of a pad and a holster was devised for the external protection of a pacemaker generator implanted in the left infraclavicular position in children. The device was accepted by the child and their caretakers and presented no problems during sports activities. The psychological side effects were beneficial and encouraged the child to normal activity and participation in organized sports.

Child↗
PubMed1987

Balloon-dilatable arterial banding prosthesis: experimental study.

Two arterial banding prostheses were developed that could be dilated by an intraluminal balloon dilator. One prosthesis consisted of radiopaque umbilical tape with a pleat secured by four 8-0 silk sutures thinly coated with silicone type A medical adhesive. This design was used to band the main pulmonary artery in five dogs, the subclavian artery in five, and the aorta in one. The second prosthesis, a stainless steel fatigued helix encased in a siliconized shield, was used to band the main pulmonary artery in two dogs and the descending aorta in two. After a mean duration of 89 days the bands were dilated with an intraluminal balloon dilator at 6 atm (608 kPa) of pressure for 30 seconds. In all 15 experiments the bands dilated and the gradient at the band was reduced. The stainless steel helix was more successful and has technical advantages for clinical application.

Angioplasty, Balloon↗
PubMed1986

Effect of pressure loading, volume loading and surgery on left ventricular chamber and myocardial stiffness in congenital heart disease, with a reevaluation of normal pediatric values.

This study assessed the effect of pressure load, volume load and surgery on left ventricular chamber stiffness (b) and myocardial stiffness (k). A normal range for chamber stiffness and myocardial stiffness was also established. A total of 44 patients were studied: 8 were control subjects, 12 had volume load and 24 had pressure load. At cardiac catheterization simultaneous high fidelity pressures (P) and left ventricular volumes (V) were obtained in one diastolic cycle. From the relation P = aVb, operant chamber stiffness (b) was estimated for each patient. Similarly, the relation between stress (sigma) and radius (B) was approximated by sigma = cBf and the myocardial stiffness (k) derived for each patient. Mean values for chamber or myocardial stiffness for the diagnostic groups were not significantly different but differed within the operative groups. Mean values for b and k were greater in the post-open heart surgery group than in the post-closed heart surgery or nonsurgical group. Although the mean values for chamber stiffness and myocardial stiffness for the diagnostic groups were not different, there were more abnormal patients in the pressure load group (9 of 24) than in the volume load group (2 of 8) when the normal range was obtained from the control group. Thus, left ventricular operant chamber and myocardial stiffness are often preserved with volume loading, less frequently with pressure loading and rarely after open heart surgery.

Adolescent↗
PubMed1986

Transvenous atrial pacing in the management of sick sinus syndrome following surgical treatment of the univentricular heart: case report and review.

An 11-year-old boy with univentricular heart type A-III underwent surgical treatment at age 10 with a modified Fontan operation. Six months postoperatively he developed intermittent periods of cyanosis and fatigue associated with profound sinus bradycardia and nodal escape. After demonstrating normal atrioventricular conduction, a transvenous atrial pacemaker was implanted. This produced a marked clinical improvement. Transvenous atrial pacing is a satisfactory method of treating sinus node dysfunction in patients with univentricular heart following the Fontan operation provided that there is normal AV conduction.

Child↗
PubMed1986

Perigraft seroma: long-term complications.

A 5 1/2-year-old child is described in whom a perigraft seroma complicating a polytetrafluoroethylene tubular graft was managed conservatively for 4 years without disruption of the function of the graft or progressive distortion of the pulmonary arteries.

Blood Vessel Prosthesis↗
PubMed1970

The role of rubella in the etiology of supravalvular aortic stenosis.

The possibility of an etiological relationship between rubella embryopathy and sporadic forms of supravalvular aortic stenosis is considered. A case is presented of a patient with rubella embryopathy and supravalvular aortic stenosis associated with pulmonary valvular and peripheral pulmonary artery stenosis, bicuspid aortic valve, aortic valve stenosis and subendothelial myocardial fibrosis. A review of the literature revealed many clinical and pathological features common to both syndromes. The hypothesis that rubella virus produced germ-cell mutation and subsequent persistence of rubella in the zygote produced further fetal damage is presented to explain these observations.

Aortic Coarctation↗
PubMed1970

The hemodynamic response of the right ventricle following acute and chronic partial obstruction of the main pulmonary artery in dogs.

In eight adult dogs the main pulmonary artery was constricted to elevate the right ventricular peak systolic pressure to 50% of the peak aortic pressure at rest. The response of the right ventricle was assessed immediately, at 30 minutes and at six months. The right ventricle responded to acute systolic loading by complete compensation. After 30 minutes there was a reduction in the right ventricular outflow tract resistance. The cardiac output, heart rate and aortic pressure were maintained. The right ventricular systolic ejection period, end-diastolic pressure, peak pressure time, mean systolic pressure, right ventricular-main pulmonary artery mean systolic gradient, right ventricular work index, systolic work and outflow tract resistance were all increased.The right ventricle in the dog was shown to have an immediate capacity to compensate for systolic loading and retains this capacity for long periods of time. The ability to increase work is accomplished by adaptations in right ventricular physiology which increase right ventricular mean systolic pressures and prolong the right ventricular ejection period.

Animals↗
PubMed1970

The hospital incidence and clinical significance of congenital heart malformations resulting from rubella embryopathy.

A retrospective study is reported of 75 children with rubella embryopathy syndrome, admitted to the Health Centre for Children, Vancouver General Hospital, during the four-year period from July 1, 1964 to July 1, 1968.Sixty-four of the 75 had cardiovascular malformations, 37 had ophthalmological defects, 31 had nerve deafness and three were mentally retarded. The most common cardiovascular defects were patent ductus arteriosus (36 patients), ventricular septal defect (22 patients) and pulmonary valvular stenosis (17 patients).Ninety-three per cent of the mothers had a history of exposure to rubella during their first trimester.The administration of gamma globulin to mothers exposed to rubella did not prevent fetal damage.Although this group of patients accounted for only 6% of children requiring open-heart surgery, it did account for 27% of the children having closed-heart surgical procedures and 10% of the case load of the cardiac catheterization laboratory.

British Columbia↗