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Biomedical subjects

S E Kirkpatrick

Publications and source records attributed to S E Kirkpatrick.

At least 37 records · Page 2Linked to original sources
PubMed1983

Congenital heart disease and pulmonary artery hypertension. I. Pulmonary vasoreactivity to 15% oxygen before and after surgery.

Pulmonary vasoreactivity at sea level was studied in 22 children before and in 15 children after corrective cardiac surgery for congenital heart disease and pulmonary artery hypertension; 8 children were studied both before and after cardiac surgery. During cardiac catheterization in 28 children, pulmonary and systemic hemodynamics were determined in room air and during breathing of 15% oxygen, which corresponds to a maximal hypoxic level commonly encountered during airplane travel. Before surgery, 19 of 22 children tolerated 15% oxygen (O2), which caused the following hemodynamic changes from room air status: the ratio of pulmonary to systemic arterial pressure increased from 0.70 to 0.78 (p less than 0.05), the ratio of pulmonary to systemic flow decreased from 2.2 to 2.0 (p greater than 0.05) and the ratio of pulmonary to systemic vascular resistance increased from 0.33 to 0.40 (p less than 0.02). In two children, severe pulmonary vasoconstriction developed within 5 minutes of 15% oxygen administration, requiring immediate discontinuation of hypoxia; neither patient had lasting deleterious effects. There was no evidence of increased pulmonary vasoreactivity in children with Down's syndrome compared with genetically normal children. After corrective surgery in 15 children (including both of the hyperreactors), no significant pulmonary vascular response to 15% oxygen was found. It is concluded that, in a small number of children with unrepaired congenital heart disease and pulmonary artery hypertension, pulmonary vascular hyperreactivity can be induced by breathing 15% oxygen; this reaction is life-threatening but reversible with the administration of 100% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

The vasoactivity of the fetal lamb ductus arteriosus studied in utero.

The ductus arteriosus of the undisturbed fetal lamb was studied chronically by techniques that allowed direct serial measurements of the calibre of the fetal channel. When the direct actions were studied of vasoactive agents on the ductus arteriosus, prostaglandins did not dilate the vessel beyond its resting dimensions. The cyclooxygenase inhibitor, indomethacin, was a potent vasoconstrictor with a plateau of the dose-effect relationship occurring at 0.2 mg/kg. Fetuses of 95--98 days gestational age were equally sensitive to indomethacin when compared to animals near term. Although the prostaglandins, PGE1, PGE2 PGF2 alpha, PGH2, PGI2 and PGG2, had no direct effect on the ductus arteriosus, PGE1, PGE2, PGH2 and PGI2 reversed the vasoconstrictor action of indomethacin. Autonomic nervous system mediators and blockers, i.e., acetylcholine, atropine, norepinephrine, propranolol, phentolamine and methoxamine, had neither direct effects on the ductus arteriosus nor any influence of indomethacin-induced vasoconstriction. The same was true of angiotensin 1, angiotensin 2, blockade of conversion of angiotensin 1 to 2, serotonin, methysergide, aminophylline, adenosine, and dibutyryl cyclic AMP. Imidazole, a blocker of thromboxane synthase, had no direct effect on the ductus arteriosus, but reduced significantly the magnitude of the indomethacin constrictor action. The major finding of this investigation was the exquisite sensitivity of the ductus arteriosus to manipulations of the prostaglandin environment. The results suggest that both locally generated prostaglandins, as well as prostanoids in the circulation, may be involved in ductal patency and closure. A high degree of control is likely of the circulation of the ductus arteriosus and constriction of the fetal channel is probably the result of an active process.

Adenosine↗
PubMed1983

Vascular consequences of subclavian artery transection for the treatment of congenital heart disease.

The acute and chronic consequences of subclavian artery transection were analyzed in the noninvasive vascular laboratory. Twenty-eight patients (aged 1 day to 4 2/12 years, median 2 months) underwent subclavian artery transection (23 Blalock-Taussig, four subclavian aortoplasty for coarctation or interrupted arch, and one division of aberrant left subclavian). Bilateral systolic brachial artery pressure (BAP) was measured by Doppler instrumentation to obtain a "BAP index": BAP1 = (operated side BAP/control side BAP). Velocity waveform tracings and bilateral forearm skin temperatures were also obtained during studies before and sequentially after operation (4 hours to 12 years). Five patients underwent exercise testing of the upper extremity. Nine patients were studied for manual preference and limb development. Before operation, mean BAP1 was 0.99. Immediately (4 to 48 hours) after operation, mean BAP1 was 0.39. Three weeks postoperatively, BAP1 was 0.62, and thereafter it remained at 0.70. All differences between preoperative, immediate postoperative and late postoperative BAP1 are significant (p less than 0.001). Exercise resulted in a significant (p less than 0.01) increase in BAP bilaterally. Forearm skin temperature was initially lower (p less than 0.01) on the operated side but approximated the control side by 1 week. Limb girth was less on the operated side (p less than 0.01), without evidence of altered manual preference. In conclusion, subclavian artery transection causes permanent reduction in BAP1. The affected limb appears to respond to increased metabolic demand by increasing limb blood flow.

Arm↗
PubMed1983

Coarctation in the first year of life. Patterns of postoperative effect.

From 1975 to 1982, 31 infants were operated upon in the first year of life for aortic coarctation and congestive heart failure. Operations performed were resection and end-to-end anastomosis (RETE) in 14, subclavian flap aortoplasty (SFA) in six, patch aortoplasty (PA) in five, and other procedures in six. Thirty of the thirty-one (97%) survived the operation. To assess the effect of operation, 26 infants were studied noninvasively with Doppler arm-to-leg pressure measurements at rest and with stress. Preoperatively, the median arm-to-leg gradient at rest was 77 mm Hg. Serial postoperative Doppler studies demonstrated progressive changes in arm-to-leg pressure gradients: 69% had residual arm-to-leg gradients that spontaneously resolved, 13% had residual gradients that persisted, 13% had progressive increase in gradient, and one child had neither early nor late gradient. Stress testing often unmasked gradients not present in the resting state. No differences were noted among the three surgical groups: RETE, SFA, and PA. From our experience, we have made four conclusions with regard to repair of coarctation of the aorta in infants. First, surgical survival is expected. Second, the effect of the operation is dynamic, with four patterns defined: (1) complete relief of coarctation, (2) transient residual coarctation, (3) persistent residual coarctation, and (4) recurrent coarctation. Third, optimal surgical therapy seems to be an eclectic approach. Fourth, physiological evaluation of coarctation in infants can be obtained by Doppler techniques in conjunction with stress testing.

Aortic Coarctation↗
PubMed1982

The "free" routine postcatheterization urogram: a cost/benefit analysis.

Postangiography urography has become routine procedure in most centers performing cardiac catheterization in children. We analyzed the x-radiation dosage and clinical yield of this procedure. Using lithium fluoride thermoluminescent dosimeters, radiation exposure to the abdomen and gonads was measured in 35 children during postangiography urography. Results of 334 consecutive routine postangiography cine-urograms were evaluated based on clinical significance and compared to previous reports on this subject. Average absorbed abdominal radiation dosage was 241 mR +/- 240 from cine-urography, 16 mR +/- 13 from fluoroscopy, and 107 mR +/- 111 from a single abdominal roentgenogram. Gonadal dosage averaged 8 mR and was uniformly less than 27 mR. Of 334 routine postangiography cineurograms, 282 (84%) were normal, 30 (9%) were technically inadequate, 12 (3%) had abnormalities that were clinically insignificant or were falsely "positive" and in 10 (3%), clinically significant urologic conditions were confirmed. Because of the low yield of clinically significant anomalies and the added radiation exposure, we no longer perform routine postangiography cine-urography in children. Following cardiac angiography, the upper renal collecting systems are examined fluoroscopically. If abnormalities are suspected or fluoroscopy is equivocal, a single abdominal roentgenogram is performed. Using this procedure, mean average absorbed abdominal radiation dose can be reduced from 241 mR to 30.5 mR.

Cardiac Catheterization↗
PubMed1982

Umbilical vascular catheters: localization by two-dimensional echocardio/aortography.

Umbilical vascular catheters are often necessary in the care of critically ill neonates. Position of the catheter tip is usually determined by roentgenography. Location of the umbilical arterial or venous catheter was determined by 2-dimensional echocardio/aortography in 55 consecutive infants and was compared to localization by thoraco-abdominal roentgenography. Most of the infants (76%) had respiratory distress syndrome or congenital heart disease. Echocaortographic localization of the umbilical arterial catheter correlated very closely (N = 50, sr = .90) with roentgenographic determination. For localization of the tip of the umbilical venous catheters, echocardiography was more accurate than roentgenography (employing contrast echocardiography for confirmation of cardiac chamber position). Two-dimensional echocardio/aortographic localization of the tip of indwelling umbilical vascular catheters is as accurate as roentgenography in the arterial system and more accurate than x-ray for umbilical venous catheters. Echocardio/aortography is superior to roentgenography (in localizing the catheter tip) because it 1) avoids ionizing radiation, 2) makes positioning of the patient unnecessary, 3) allows visualization of the catheter in relation to cardiovascular structures, and 4) may allow demonstration of intraarterial thrombo-emboli.

Aortography↗
PubMed1982

Two-dimensional echocardiographic visualization of the aortic arch by right parasternal scanning in neonates and infants.

Echocardiography has previously been of limited use in visualizing the aorta in neonates and infants. Using a new technique--right parasternal scanning--the aortic arch and brachiocephalic vessels were studied in 50 children under 18 months of age. Complete visualization was accomplished in 47 patients including those 1) under 1,000 grams, 2) with indwelling endotracheal tubes, 3) who had D- or L-transposition, or 4) with right or double aortic arch. Inadequate studies were related to bilateral pneumothorax (2 neonates) and lack of cooperation (1 infant). Close correlation was obtained between images of the aorta by echocardiography and by angiography. Two-dimensional echocardiography can now visualize the aortic arch in small infants and children. In conjunction with another new technique--simultaneous Doppler flow-detection--coarctation of the aorta can be completely evaluated noninvasively in children of all ages including neonates.

Aorta, Thoracic↗
PubMed1982

Complex cyanotic congenital heart disease correctable with an intra-atrial baffle.

The clinical, angiocardiographic, and surgical findings in a cyanotic child with dextrocardia, L-loop, laterally inverted but otherwise normally related great arteries, and situs ambiguus are described and compared with other similar cases. Electrocardiographic, echocardiographic, and angiographic data are reviewed, and the segmental approach to diagnosis is stressed. Both systemic and pulmonary veins returned to the right-sided atrium. Blood then passed either through the mitral valve to the morphologically left ventricle and to the aorta or through an atrial septal defect to a small left-sided atrium, right ventricle, and pulmonary artery. Total correction was undertaken with an intra-atrial baffle to direct pulmonary venous return to the morphologically right ventricle and systemic venous return to the right ventricle. The subpulmonic stenosis was alleviated with an outflow patch.

Blood Vessel Prosthesis↗
PubMed1982

Pediatric cardiac catheterization with same-day discharge.

A system was developed for cardiac catheterization in children without overnight hospital stay (called same-day discharge). Over a 4 year period, 233 children (aged 5 weeks to 20 years) had catheterization with same-day discharge staying an average of 11.8 hours in the hospital. In all but 1, no problems occurred after hospital discharge; 1 child required readmission for psoas tendinitis after retrograde aortography. Same-day discharge was safely applied regardless of the patient's age, diagnosis, and use of systemic heparinization, large-bore sheaths, retrograde arterial catheterization, or cineangiography. The hospital-related cost of pediatric cardiac catheterization was reduced 29% compared with that of the standard 42 hour hospital stay. Same-day discharge provides attractive elements to the physician and institution involved in cardiac catheterizations, for example: (1) improved medical care by a decrease in the length of hospitalization, (2) a significant reduction in medical costs, and (3) elimination of time pressure in training and teaching as well as therapeutic decision-making. Critical factors for the successful application of same-day discharge are coordination of multiple health care professionals and physician judgment of the patient's clinical status. We speculate that reassessment of other hospital-oriented procedures may foster the development of methods for improving medical care or reducing cost, or both.

Adolescent↗
PubMed1981

Radiation exposure to the child during cardiac catheterization.

Few data are available regarding radiation exposure to children during cardiac catheterization. Using lithium fluoride thermoluminescent dosimeters, radiation exposure was measured during precatheterization chest roentgenography, fluoroscopy (hemodynamic assessment phase of catheterization) and cineangiography in 30 infants and children, ages 3 days to 21 years. Dosimeters were placed over the eyes, thyroid, anterior chest, posterior chest, anterior abdomen, posterior abdomen and gonads. Average absorbed chest doses were 24.5 mR during chest roentgenography, 5810 mR during catheterization fluoroscopy and 1592 mR during cineangiography. During the complete catheterization, average doses were 26 mR to the eyes, 431 mR to the thyroid area, 150 mR to the abdomen and 11 mR to the gonads. Radiation exposure during pediatric cardiac catheterization is low to the eyes and gonads but high to the chest and thyroid area. To decrease radiation dosage we suggest (1) low pulse-rate fluoroscopy; (2) substitution of contrast echocardiography for cineangiography; (3) large-plate abdominal/gonadal shielding; (4) a selective shield for thyroid area; (5) a very small field during catheter manipulation. Minimum radiation consistent with accurate diagnosis is optimal; however, erroneous or incomplete diagnosis is more dangerous than radiation-related hazards.

Adolescent↗
PubMed1981

Effects of indomethacin on fetal rat lungs: a possible cause of persistent fetal circulation (PFC).

Indomethacin, because of its prostaglandin inhibition, may cause constriction of the ductus arteriosus and affect the pulmonary circulation. To study this possibility, we gave indomethacin daily by gavage to two groups of pregnant rats from the 17th day of pregnancy through delivery (group 1, 2 mg/kg/day; group 2, 4 mg/kg/day). Group 3, untreated control pregnant rats received saline. The pups were killed 30 min after birth and heart-lung preparations were perfused with glutaraldehyde. Appropriate blocks were processed for quantitative morphometry of the pulmonary arteries and arterioles. For analysis, the vessels were grouped by external diameter, i.e., less than 30, 30 to 50, and 50 to 100 micron. Groups 1 and 2 showed an increased medial smooth muscle mass in both 30 to 50 and 50 to 100-micron vessels as indicated by media thickness and medial areas (P less than 0.05). Muscularized arterioles, less than 30 micron, were present in groups 1 and 2, but not in controls. The relative mass of lung parenchymal components were determined by point counting. Indomethacin-treated animals had an increased saccular wall mass, decreased airspace mass, and a decreased capillary to saccular wall ratio (P less than 0.05). These results show that the fetal pulmonary circulation's response to indomethacin comprises the appearance of medial hypertrophy and newly muscularized arterioles. When these changes occur in lungs with immature, thick saccular walls, there is a decreased surface for oxygen exchange and an increased pulmonary vascular resistance resulting in a persistent fetal circulation.

Animals↗
PubMed1980

Axial left ventriculography in discrete subaortic stenosis.

Left ventricular angiograms of six children were reviewed, and it was found that those obtained in axial (long axial oblique and hepatoclavicular) projections enhanced precision in the diagnosis of subvalvular aortic stenosis. The methods for obtaining these views are described, and the results presented. Axial views are never inferior to standard (posteroanterior, lateral, and right anterior oblique) projections, and are usually superior to them, especially when there are associated lesions, such as ventricular septal defects, left-sided obstructive lesions, and patent ductus arteriosus.

Angiography↗
PubMed1980

Assessment of patent ductus arteriosus in preterm infants by single lateral film aortography.

Differentiation of a hemodynamically significant cardiovascular abnormality from lung disease in the newborn infant may remain problematic after clinical, radiographic, and echocardiographic evaluation. Single-view aortography was performed in 38 preterm and one full term infant in the neonatal special care nursery. Special lateral views were obtained consisting of either a horizontal x-ray beam with oblique angulation of the supine patient or a vertical bean with 30 degree head-up angulation of the patient. These views projected the ductus caudal to the aortic arch and enabled visualization of the entire length of the ductus and focal constrictions of the ductus. The severity of patent ductus arteriosus was judged by anatomic (diameter of the ductus compared to the descending aorta) and physiologic (preferential opacification of the aortic arch or pulmonary circulation) criteria.

Aortography↗
PubMed1980

Influence of indomethacin on renal function in conscious newborn lambs.

Transient renal dysfunction has been observed in some premature infants who received indomethacin to constrict patent ductus arteriosi, and it has been suggested that this complication may be dose related. Accordingly, the present study was designed to investigate the influence of high (7.5 mg/kg) and low (0.2 mg/kg) doses of indomethacin on effective renal blood flow, glomerular filtration rate, urine flow, sodium and potassium excretion and plasma levels of indomethacin in conscious newborn lambs studied continously over a 24-hour period. When compared to control lambs, both indomethacin doses reduced effective renal blood flow significantly at 2--4 h, but only high doses significantly reduced renal blood flow at 22--24 h (6.5 +/- 0.9 vs. 13.4 +/- 1.4 ml/min/kg, respectively; p less than 0.001). At 8-16 and 16-24 h after drug administration, urine flow was significantly lower than in the control group only in high-dose lambs (p less than 0.05). During the 16 to 24-hour period, urine flow for control, low- and high-dose animals was 0.15 +/- 0.01, 0.14 +/- 0.01, and 0.08 +/- 0.02 ml/min/kg, respectively. Glomerular filtration rate and sodium and potassium excretion rates were not affected by either indomethacin dose.

Animals↗
PubMed1978

Closure of the patent ductus arteriosus with ligation and indomethacin: a consecutive experience.

This report summarizes a consecutive experience with 59 preterm infants with clinical, radiographic, and echocardiographic findings of a large patent ductus arteriosus. Thirty-five infants who met defined criteria received indomethacin, and 24 infants underwent PDA ligation. Analysis of the clinical course of these infants revealed no selective indomethacin morbidity and suggests that infants undergoing ligation require more prolonged ventilator therapy with increased exposure to FiO2 greater than or equal to 0.3. Mortality rates between ligated and pharmacologically treated groups were similar. This study documents that inhibition of prostaglandin synthesis to constrict and close the PDA in the premature infant is an effective alternative to operative closure.

Ductus Arteriosus, Patent↗
PubMed1978

Prostaglandins: physiological and clinical correlations.

This review has necessarily been incomplete. We have not considered the potentially important interplay between PGs and male and female reproductive functions or the well-documented relationships between PGs and inflammation. We have examined the evidence for the influence of PGs on the pulmonary and peripheral vascular circulations and the interaction between PGs and the kidney and the autonomic nervous system. Emphasis has been placed on the role of PGs in the control of the circulation of the ductus arteriosus, and our recent experiences with indomethacin in sick, preterm infants with large left-to-right ductal shunting have been outlined. Existing information has been reviewed concerning PGs and the fetal-placental and fetal-maternal units. It should be clear that a host of proposed functions exists for PGs; many remain tentative in light of the conflicting and often bewildering results of animal experimentation.

Animals↗