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Biomedical subjects

J S Kan

Publications and source records attributed to J S Kan.

At least 37 records · Page 2Linked to original sources
PubMed1990

Balloon pulmonary valvuloplasty: results of the Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Eight hundred twenty-two balloon pulmonary valvuloplasties were reported to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry. Before and after systolic outflow gradients were recorded in 784 valvuloplasties, and the gradient decreased from 71 +/- 33 to 28 +/- 21 mm Hg. The sites of residual obstructions could be ascertained in 196 patients. In these, the total systolic outflow gradients decreased from 85 +/- 41 mm Hg to 33 +/- 27 mm Hg. Of this total residual gradient, 16 +/- 15 mm Hg was transvalvar and 18 +/- 24 mm Hg was infundibular. The degree to which infundibular obstruction subsequently resolved was not determined in this study. The procedure was less effective in reducing outflow gradients in patients with dysplastic valves with or without Noonan's syndrome. There were 5 major complications (0.6%), including 2 deaths (0.2%), a cardiac perforation with tamponade (0.1%) and 2 tricuspid insufficiencies (0.2%). There were 11 minor complications (1.3%) and 21 incidents (2.6%). The incidence of major complications, minor complications and incidents was inversely related to age; it was substantially higher in infants and, in particular, neonates. Balloon pulmonary valvuloplasty is a safe and effective method of lowering pulmonary outflow gradients in infants, children and adults. Small transvalvar and varied infundibular gradients commonly are present at the end of the procedure. Assessing the full effect of the procedure requires intermediate-term follow-up and assessing the duration of relief requires long-term follow-up.

Adult↗
PubMed1990

Balloon aortic valvuloplasty: results of the Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Data from 204 children and infants who underwent aortic balloon valvuloplasty between 1982 and 1986, reported to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry, were reviewed. Valvuloplasty was successful in 192 of 204 children, reducing the peak systolic left ventricular ejection gradient from 77 +/- 2 to 30 +/- 1 mm Hg, p less than 0.001. The same degree of aortic stenosis gradients reduction was noted in both the 38 children under 1 year of age and in the 166 children over 1 year of age. Significant complications included death, aortic regurgitation and femoral artery thrombosis or damage. The incidence of these complications correlated with the age of the child, the ratio of valvuloplasty balloon size/anulus size, or both. The data suggest that percutaneous balloon valvuloplasty provides effective acute relief of valvar aortic stenosis in both infants and children. However, long-term follow-up data are necessary before balloon valvuloplasty can be established as a treatment of choice for congenital valvar aortic stenosis.

Aortic Valve↗
PubMed1990

Balloon angioplasty--branch pulmonary artery stenosis: results from the Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Balloon angioplasty for branch pulmonary artery stenosis was reported from 27 institutions to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry. One hundred eighty-two procedures were performed in 156 patients ranging in age from 0.2 to 46.2 years (mean 7.7). Short-term angiographic appearance, hemodynamic results and immediate complications were recorded. Vessel dimension at the site of stenosis increased from 4.5 +/- 2.0 (mean +/- standard deviation) to 6.8 +/- 3.0 mm (p less than 0.001) with greater increases in vessel dimension at the site of stenosis if the balloon diameter was greater than 3 X the original dimension of the stenosis. There was no significant benefit related to age or prior surgical intervention. The mean peak systolic pressure gradient was reduced from 49 +/- 25 to 37 +/- 26 mm Hg (p less than 0.001) and pressure proximal to the stenosis decreased from 69 +/- 25 to 63 +/- 24 mm Hg (p less than 0.001). Complications occurred in 21 patients and included vessel rupture and death in 2 patients, vessel perforation or rupture with survival in 3, cardiac arrest and death in 1, paradoxical embolism and death in 1 and low output and death in 1. Balloon angioplasty for branch pulmonary artery stenosis increases vessel dimension at the site of stenosis, reduces systolic pressure gradient and to a minor degree, reduces proximal pressure. Long-term outcome and potential complications are as yet uncertain.

Catheterization↗
PubMed1988

MRI demonstration of pulmonary sequestration.

The preoperative evaluation of pulmonary sequestration requires delineation of the arterial supply and venous drainage of both the sequestered segment and the neighboring lung. In this case magnetic resonance imaging was the sole modality which demonstrated all components of the arterial and venous circulations of a sequestration and the remainder of the ipsilateral lung.

Bronchopulmonary Sequestration↗
PubMed1988

Changes in myocardial repolarization in patients undergoing balloon valvuloplasty for congenital pulmonary stenosis: evidence for contraction-excitation feedback in humans.

Alterations in ventricular loading conditions lead to changes in action potential duration and arrhythmias via contraction-excitation feedback; a decrease in load leads to prolongation of repolarization. To determine whether changes in right ventricular load alter ventricular repolarization in man, the corrected QT interval, a measure of overall ventricular repolarization, was measured in 32 patients before and after valvuloplasty for pulmonary stenosis. Right ventricular systolic pressure decreased (82.5 +/- 30.7 to 40.5 +/- 9.5 mm Hg, p less than .001) and the QTc increased concurrently (409.1 +/- 24.3 to 440.7 +/- 28.0 msec, p less than .001) after successful valvuloplasty. The increase in QTc was most marked for those patients with a greater than 30 mm Hg decrease in right ventricular pressure (40.0 +/- 23.3 vs 16.3 +/- 21.3 msec, p = .006). In a subset of seven patients in whom monophasic action potentials were recorded, monophasic action potential duration, a measure of local repolarization, was prolonged (230.0 +/- 24.3 vs 216.9 +/- 21.9, p less than .001) after successful valvuloplasty, confirming that the QTc prolongation reflected changes in local ventricular repolarization. In addition, during nine acute right ventricular outflow tract occlusions in a subset of six patients, monophasic action potential duration shortened (206.6 +/- 17.6 vs 221.7 +/- 20.9 msec, p less than .01) and early afterdepolarizations developed consistent with contraction-excitation feedback. These data suggest that, in humans, changes in mechanical load are associated with changes in ventricular repolarization consistent with contraction-excitation feedback.

Action Potentials↗
PubMed1984

Percutaneous transluminal balloon valvuloplasty for pulmonary valve stenosis.

Transluminal balloon valvuloplasty was used to treat congenital pulmonary valve stenosis in 20 patients. Follow-up cardiac catheterization was performed in 11 patients at intervals of from 2 to 12 months after the procedure. Peak systolic pressure gradient across the pulmonic valve decreased from 68 +/- 27 to 23 +/- 5 mm Hg (p less than .001) after valvuloplasty. There were no complications. Follow-up catheterization demonstrated persistent relief of right ventricular hypertension in the patients with typical pulmonary valve stenosis.

Adolescent↗
PubMed1983

Percutaneous transluminal angioplasty of aortic graft stenoses.

Postoperative aortic graft anastomotic stenoses at nine sites in eight patients were successfully treated with percutaneous transluminal angioplasty. There was a decrease in peak systolic pressure gradient in all eight patients, and in seven of the eight patients symptoms of claudication disappeared immediately after angioplasty. Four of the eight patients remained asymptomatic at follow-up. Ankle/arm indices were obtained before and after angioplasty in five patients, with postangioplasty improvement in all five.

Aged↗
PubMed1983

Treatment of restenosis of coarctation by percutaneous transluminal angioplasty.

Percutaneous transluminal angioplasty (PTA) was used successfully to treat coarctation restenosis in seven patients. The patients were 10 months to 17 years old at the time of the angioplasty, and the initial coarctation repair had been performed 10 months to 16 1/2 years previously. PTA reduced the systolic pressure gradient across the coarctation from a mean of 58 mm Hg before the procedure to a mean of 13 mm Hg immediately after PTA. Follow-up has been from 1 to 14 months and indicates that the decrease in the systolic pressure gradient is persistent.

Adolescent↗
PubMed1977

Quantification of the normal Frank and McFee-Parungao orthogonal electrocardiogram at ages two to ten years.

A quantification of the Frank and McFee-Parungao orthogonal electrocardiogram of 175 normal children, ages 2-10 years is presented. There are significant differences in age groups 2-5 and 6-10. The QRS voltages of the younger group demonstrate 1) greater Z anterior, 2) greater initial X right, 3) greater terminal X right, 4) smaller Y inferior, and 5) the T vector is oriented more posteriorly. There are significant differences between the two lead systems. 1) Frank spatial voltages are 70% of those of McFee. 2) Frank X left is 70% of McFee, but terminal X right is 75% and initial X right is 60% of McFee. 3) Frank Y inferior is 78% of McFee, but initial Y superior is 83% and terminal Y superior 61% of McFee. 4) Frank Z anterior is 64% and Frank Z posterior is 70% of McFee. 5) In terms of ratios the Frank is relatively less inferior, about equally posterior and more terminally right. 6) The T vector is more posterior in Frank than McFee.

Age Factors↗