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Biomedical subjects

E Birk

Publications and source records attributed to E Birk.

29 records · Page 2Linked to original sources
PubMed1995

Repeated repair of tetralogy of Fallot. Report of 11 cases and review of the literature.

Eleven patients underwent late repeated correction of tetralogy of Fallot in 1991-1993. The previous operation was repair of simple Fallot's tetralogy in seven cases, repair plus transannular patch in one case and repair of tetralogy and pulmonic atresia in three cases. The indications for reoperation were residual ventricular septal defect, right ventricular outflow tract (R.V.O.T.) obstraction, residual branch pulmonary artery stenosis, aneurysmal dilatation of R.V.O.T. Patch or combination of any of the above. At reoperation these defects were corrected. The post operative course was uneventful in eight patients. Two required mechanical ventilation for 2-3 days, and one underwent another operation for residual branch pulmonary artery stenosis. The functional and haemodynamic results were good in ten patients, and one had residual distal pulmonary artery stenosis. There were no death during 2 years of follow-up. Repeated correction of tetralogy of Fallot thus had low postoperative morbidity and good haemodynamic results. For the relatively few patients initially found to have tetralogy of Fallot and pulmonic atresia, the outcome may be less favorable.

Anastomosis, Surgical↗
PubMed1995

Definitive repair of tetralogy of fallot. A review of 104 cases.

Definitive repair of tetralogy of Fallot was performed on 104 children, including 42 younger than 2 years (24 < 1 year and 7 < 6 months). Twenty-two had previous shunt. Transannular patching was required in 60 cases and conduit grafts in two. During 60-day postoperative observation, five patients died. Of the 99 survivors, 93 recovered without complications, three required prolonged mechanical ventilation, two reoperation and one balloon dilatation for residual left pulmonary artery stenosis. Morbidity and mortality were not significantly higher in the patients younger than 12 months, although transannular patching was more common in that age group. Previous shunt operations entailed higher prevalence of distal stenosis and distortion of the pulmonary arteries, which often necessitated surgical repair, and also considerably increased postoperative morbidity and mortality. As the outcome in definitive repair of Fallot's tetralogy is favourable, even in patients younger than 12 months, and as preliminary shunt operations are associated with heightened perioperative morbidity and mortality rates in definitive repair, we advocate the definitive operation for all young patients with severe cyanosis or cyanotic spells.

Adolescent↗
PubMed1995

Interruption of right sided aortic arch. Case report and review of the literature.

Interrupted right sided aortic arch is a very rare anomaly, and to our knowledge only one such case in which the patient underwent complete repair has been recorded in the literature. Twelve additional cases were found on autopsy or underwent palliative surgery. We present the case of a 25-day-old infant with an interrupted right sided aortic arch. The anomaly was repaired by a one-stage surgical approach, and the patient discharged from the hospital. Surgical technique considerations are discussed.

Anastomosis, Surgical↗
PubMed1994

Total cavopulmonary connection (TCPC) for complicated congenital heart malformations.

We reviewed our experience with 40 patients who had undergone total cavopulmonary connection (TCPC) during the past three years. Thirty-one patients had functional single ventricle; only 8 of these with tricuspid atresia, five patients had complex forms of double outlet right ventricle (DORV), and four complex A-V canal. Previous palliative procedures, mostly systemic-pulmonic shunts, were performed in 34 patients. Concomitant procedures were required in 18 patients, mainly reconstruction of distorted pulmonary arteries. A subgroup of 14 high risk patients, that did not fulfil the classical Fontan criteria, underwent 4 mm fenestration of the intra-atrial baffle. There were three (7.5%) early postoperative deaths which occurred in the higher risk group (fenestrated group). However, the remaining patients were all in functional class I or II. Total cavopulmonary connection provides reasonably good definitive palliation for patients with single ventricle physiology. Fenestration of the intra-atrial baffle increases the number of candidates suitable for the Fontan procedure, although the exact inclusion criteria for these patients has yet to be defined.

Adolescent↗
PubMed1994

A one-way, valved, atrial septal patch in the management of postoperative right heart failure. An animal study.

Patients who undergo surgical repair of congenital heart defects that are characterized by hypoplastic right ventricle or pulmonary hypertension are at high risk for the development of postoperative right heart failure. To minimize this risk, a new one-way, valved, atrial septal patch was developed that serves as an artificial one-way foramen ovale. The feasibility of this device was tested in five dogs in which reversible right heart failure had been induced. Use of the one-way valved patch significantly improved right ventricular performance and reduced right ventricular hydrostatic pressures. The interatrial pressure gradient was reduced from 10 +/- 3.5 mm Hg during right heart failure to 4.4 +/- 1.4 mm Hg. When the device was opened, cardiac output increased significantly. This hemodynamic improvement was achieved at the expense of systemic arterial desaturation, which was, however, well tolerated. When the state of right heart failure was reversed, the one-way valved patch spontaneously closed, allowing no interarterial shunting. The results of this experimental trial suggest that this device can play a useful role in selected patients in whom postoperative right heart failure can be anticipated after surgical repair of certain congenital heart defects.

Animals↗
PubMed1994

Total cavopulmonary connection for complicated congenital heart malformations.

We reviewed our experience with 40 patients who had undergone total cavopulmonary connection during the past 3 years. Thirty-one patients had functional single ventricle, only 8 with tricuspid atresia; five had complex forms of double outlet right ventricle, and 4 complex A-V canal. Previous palliative procedures, mostly systemic-pulmonic shunts, were performed in 34 patients. Concomitant procedures, mainly reconstruction of distorted pulmonary arteries, were required in 18 patients. A subgroup of 14 high risk patients, who did not fulfil the classical Fontan criteria, underwent 4 mm fenestration of the intraatrial baffle. There were 3 (7.5%) early post-operative deaths that occurred in the higher risk group (fenestrated group). However, the remaining patients were all in functional class I or II. Total cavopulmonary connection provides reasonably good definitive palliation for patients with single ventricle physiology. Fenestration of the intraatrial baffle increases the number of candidates suitable for the Fontan procedure, although the exact inclusion criteria for these patients has yet to be defined.

Adolescent↗
PubMed1992

Effects of thyroid hormone on myocardial adrenergic beta-receptor responsiveness and function during late gestation.

To assess the effect of fetal hypothyroidism during late gestation on postnatal cardiovascular responsiveness, we measured heart rate and cardiac output responses to isoproterenol in newborn lambs. To evaluate the effect of such altered thyroid status on the development of beta-adrenergic signaling cascade, we measured myocardial beta-adrenergic receptor concentration and affinity, guanine nucleotide regulatory protein density, and adenylyl cyclase responsiveness. Twenty fetal lambs underwent either thyroidectomy and line placement or line placement alone at 128-130 d gestation. Five thyroidectomized and six control newborns were treated with isoproterenol, five thyroidectomized and four control newborns were killed upon delivery and tissue was obtained for biochemical studies, and four additional animals were delivered and killed at 126 d gestation and tissue was obtained for receptor analysis. Of the newborns treated with isoproterenol, the thyroidectomized lambs showed lower increase in heart rate and cardiac output compared with euthyroid newborns. Compared with the myocardium of normal newborns of similar gestation, the myocardium of the newborns who underwent fetal thyroidectomy failed to show the normal increase in beta-adrenoceptors accompanied by reduction in beta-adrenergic-stimulated adenylate cyclase activity. These results suggest that near term, the normal development of ovine fetus myocardial beta-adrenergic receptor is affected by thyroid hormones.

Adenylyl Cyclases↗
PubMed1992

Myocardial cholinergic signaling changes with age.

We examined the linkage of cholinergic receptors to the phosphoinositide signaling pathway to elucidate one facet of the autonomic response mechanism in fetal and adult sheep. Cholinergic stimulation with carbachol increases the production of 3H-inositol mono-, bis-, and trisphosphates in a time- and concentration-dependent manner in both fetal and adult myocardium. However, the maximal stimulation of inositol polyphosphates above basal activity was much greater in fetal (120 +/- 11%) than in adult (20 +/- 7%) myocardium (mean +/- SEM). Saturation binding analysis of myocardial muscarinic receptors using 3H-N-methylscopolamine revealed significantly higher receptor concentration in fetal (240 +/- 25 fmol/mg protein) than in adult (78 +/- 15 fmol/mg protein) myocardium (mean +/- SEM). Binding competition studies revealed a pattern of selectivity-atropine less than 4-diphenylacetoxy-N-methylpiperidine methiodide less than pirenzepine less than or equal to (4-hydroxy-2-butynyl)-1-trimethylammonium m-chlorocarbanilate chloride less than or equal to 11-2[[2-[(diethylamino)-methyl]-1-piperidinyl]acetyl]-5, 11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one 116-compatible with the presence of muscarinic receptor (MR)2, MR3, and/or MR5 subtypes. Receptor subtype determination by Northern blot analysis revealed mRNA specific for the MR2 subtype in both fetal and adult myocardium, although expression was greater in fetal heart. We conclude that decreases in MR2 subtype protein and mRNA levels parallel the age-related decrease in carbachol-stimulated PLC activity. Our studies demonstrate differences between fetal and adult myocardium in the concentration of muscarinic cholinergic receptors and their linkage to a putative calcium mobilizing signaling pathway and suggest that this pathway may play a different role in the fetus than in the adult.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

Echocardiographic evaluation of dilated cardiomyopathy in the human fetus.

The diagnosis of dilated cardiomyopathy was established and subsequently confirmed in 6 of 625 fetuses studied by echocardiography. All 6 had structurally normal hearts. Abnormal findings included reduced fractional shortening index in 5, atrioventricular valve regurgitation in 3, abnormal chamber dimensions in 3 and nonimmune hydrops in 4. In 2 fetuses referred because of a family history of dilated cardiomyopathy in previous siblings, echocardiographic abnormalities were absent on a first examination performed at 20 weeks of gestation. This suggested that a normal fetal echocardiogram in a midtrimester fetus does not always rule out the subsequent development of dilated cardiomyopathy. However, all fetuses followed serially developed some abnormality later in pregnancy. Only 2 neonates survived, 1 of whom required a heart transplant during infancy. Death from cardiac failure occurred in 1 fetus and 3 neonates. This study demonstrates that dilated cardiomyopathy may develop during fetal life and might be diagnosed by echocardiography if serial studies are performed. Dilated cardiomyopathy presenting prenatally appears to have a poor prognosis.

Cardiomyopathy, Dilated↗
PubMed1988

Determination of pulmonary to systemic blood flow ratio in children by a simplified Doppler echocardiographic method.

Doppler echocardiographic determination of the pulmonary to systemic blood flow (Qp/Qs) ratio requires calculation of pulmonary artery and aortic luminal areas and integrals of the Doppler systolic velocity curves. To simplify the Doppler calculation of the Qp/Qs ratio, the square of the ratio of pulmonary to aortic luminal diameters, substituted for the ratio of vessel areas, was multiplied by the ratio of pulmonary to aortic peak flow velocities, substituted for the ratio of velocity time integrals. The Qp/Qs ratios were calculated by both the conventional and the simplified Doppler method in 42 children, 1 month to 16 years of age. Fifteen children had no evidence of shunt and 27 had an intracardiac left to right shunt at the atrial or ventricular level, or both. In children with a shunt, the Qp/Qs ratio obtained at cardiac catheterization by oximetry ranged from 1.4:1 to 4.3:1. Both the conventional and the simplified Doppler Qp/Qs ratios correlated well with the oximetric Qp/Qs ratios (r = 0.94 and 0.93, respectively). Since the pulmonary to aortic luminal area ratio and velocity time integral ratio varied in each patient, neither measurement alone correlated well with the oximetric Qp/Qs ratio and, therefore, neither alone could be used as an estimate of the Qp/Qs ratio. The simplified Doppler calculation of the Qp/Qs ratio, which requires less time and no computer facilities, provides an excellent estimate of the Qp/Qs ratio in children.

Adolescent↗