PubMed Health⌕ Search

Biomedical subjects

R E Hawker

Publications and source records attributed to R E Hawker.

At least 19 recordsLinked to original sources
PubMed2004

Late aortic root dilatation in tetralogy of Fallot may be prevented by early repair in infancy.

The objectives of this study were to examine the relative contributions of development and hemodynamics in aortic root dilatation of tetralogy of Fallot, to assess the impact of systemic to pulmonary artery shunt on aortic annular size, and to seek any relationship between the timing of corrective surgery and subsequent aortic root size. We performed a retrospective analytical study at a tertiary referral center of M-mode and two-dimensionol aortic root measurements in children with tetralogy of Fallot prior to any surgical or palliative intervention, after insertion of a surgical shunt, and on intermediate and long-term follow-up post-repair. The main outcome measures were aortic root diameter prior to correction, after palliative shunt insertion, and after definitive repair. The study found that the aortic root is enlarged in unrepaired tetralogy of Fallot irrespective of age, increased in the first 3-6 months after palliative shunt surgery, and persisted into adulthood in those repaired after 1 year of age. Age-corrected aortic root dimensions normalized by mid-childhood in those who were repaired in infancy. Preexisting aortic root dilatation normalizes by 7 years of age in patients with tetralogy of Fallot who have been repaired in infancy, whereas it persists into adulthood in the group repaired post-infancy.

Age Factors↗
PubMed2000

Role of ischemia and infarction in late right ventricular dysfunction after atrial repair of transposition of the great arteries.

OBJECTIVES: This study was conducted to assess whether myocardial ischemia and/or infarction are involved in the pathogenesis of late right ventricular dysfunction in adult survivors of atrial baffle repair for transposition of the great arteries in infancy. BACKGROUND: The medium-term success of intraatrial baffle repair for transposition of the great arteries is good, with many patients surviving into adult life, but prognosis can be limited by progressive right ventricular dysfunction. We hypothesized that ongoing myocardial ischemia and/or infarction are important factors in the pathogenesis of this complication. Radionuclide techniques offer an opportunity to study both myocardial perfusion and concomitant ventricular wall motion. METHODS: Dipyridamole sestamibi single-photon emission computed tomography followed by rest sestamibi single-photon emission computed tomography was used to assess right ventricular myocardial perfusion, wall motion, wall thickening and ejection fraction in 22 adolescents/young adults who had undergone atrial baffle repair for simple transposition of the great arteries at median 6.7 (range 0.5 to 54) months of age. The patients were aged 10 to 25 (median 15.5) years; 19 in New York Heart Association class I, 2 in class II and 1 in class III. All were in a regular cardiac rhythm during the studies. The right ventricular tomographic images were examined in three parallel and two orthogonal planes, analyzed in 12 segments. RESULTS: Perfusion defects were evident in all patients in at least one segment, in either the rest or stress images. Twelve patients (55%) demonstrated fixed defects only, nine (41%) had fixed and reversible defects and one (4.5%) had reversible defects only. Concomitant wall-thickening abnormalities occurred in 83% of segments with fixed perfusion defects, mirrored by a reduction in wall motion in 91% of segments analyzed. Right ventricular ejection fraction was correlated with age (R = 0.62; p = 0.002), and with wall-thickening abnormalities (R = 0.60; p < 0.005). CONCLUSIONS: Reversible and fixed perfusion defects with concordant regional wall motion abnormalities occur in the right (systemic) ventricle 10 to 20 years after Mustard repair for transposition of the great arteries; this may be important in the pathogenesis of late right ventricular dysfunction in this group.

Adolescent↗
PubMed1999

Right ventricular dysfunction in congenitally corrected transposition of the great arteries.

Although right ventricular (RV) dysfunction is an important complication in subjects with congenitally corrected transposition of the great arteries, its pathogenesis is poorly understood. We assessed the role of RV myocardial perfusion and found perfusion defects at rest in all 20 patients, involving 4.6 +/- 2.3 of a total of 12 segments; the extent of the resting perfusion defects correlated inversely with the RV ejection fraction.

Adolescent↗
PubMed1999

Simplified single patch technique for the repair of atrioventricular septal defect.

OBJECTIVE: Because of the complexity of traditional 1- and 2-patch techniques for the repair of complete atrioventricular septal defect, we modified our repair technique to avoid the use of any ventricular septal patch material. We report our prospective experience with this simplified 1-patch technique. METHOD: Forty-seven consecutive patients between May 1995 and August 1998 underwent repair with the use of this technique without modification. Repair was done in all patients by direct suturing of the common atrioventricular valve leaflets to the crest of the ventricular septum. No division of valve leaflets was necessary. A single pericardial patch was used to close the defect in the atrial septal component. Follow-up included electrocardiography and echocardiographic assessment of ventricular function, atrioventricular valve function, and adequacy of the left ventricular outflow tract. RESULTS: There were 2 deaths (4%), only 1 cardiac related, in the series. There were 17 male patients and 30 female patients. Mean age at repair was 5.6 months (median, 3.4 months). Associated lesions were repaired in 19 patients (40%). Mean follow-up was 1.85 years (median, 1.9 years). There was no heart block. There were no significant residual ventricular septal defects detected and no left ventricular outflow tract obstruction seen on echocardiography in any patient to date. Mitral valve status after operation was assessed as no incompetence in 13 patients (28%), minimal in 19 patients (40%), mild in 12 patients (26%), and moderate in 3 patients (6%). CONCLUSION: The repair of complete atrioventricular septal defect by direct suturing of the atrioventricular valve leaflets to the crest of the ventricular septum with a single-patch technique greatly simplifies the repair and does not lead to left ventricular outflow tract obstruction nor interfere with valve function.

Aorta↗
PubMed1998

Myocardial perfusion defects and associated systemic ventricular dysfunction in congenitally corrected transposition of the great arteries.

BACKGROUND: Patients with systemic ventricles of right ventricular morphology are at high risk of contractile dysfunction, the cause of which has not been fully elucidated. OBJECTIVE: To assess whether ischaemia or infarction contributes to ventricular impairment in unoperated patients with uncomplicated congenitally corrected transposition of the great arteries (TGA) by studying myocardial perfusion and function. SETTING: Paediatric and adult congenital cardiac clinics of a tertiary referral centre. PATIENTS: Five patients with congenitally corrected TGA but without associated structural cardiac defects (aged 3.5 to 34 years). INTERVENTIONS: Maximal exercise stress testing using standard or modified Bruce protocols. Sestamibi (technetium-99m methoxy isobutyl isonitrile) scanning after isotope injection at maximal exercise and rest. MAIN OUTCOME MEASURES: Maximum exercise capacity; right ventricular myocardial perfusion, regional wall motion, and thickening; right ventricular ejection fraction. RESULTS: The two youngest patients (3.5 and 11 years) had normal exercise capacity for age, while the others had reduced exercise performance. Sestamibi scanning showed reversible myocardial ischaemia in four patients and fixed defects indicating infarction in five. Irreversible defects were mostly associated with impaired wall motion and thickening. The ejection fraction was normal (65%) in the youngest patient but < 55% in the others (mean (SD) 47(11)%). CONCLUSIONS: Patients with unoperated congenitally corrected TGA have a high prevalence of myocardial perfusion defects, with consequent abnormalities of regional wall motion and thickening, and impaired ventricular contractility. These data suggest that ischaemia and infarction are important in the pathogenesis of ventricular failure in this condition.

Adolescent↗
PubMed1994

Amiodarone management of junctional ectopic tachycardia after cardiac surgery in children.

OBJECTIVE: To assess the effectiveness and safety of amiodarone in the treatment of junctional ectopic tachycardia (JET) after open heart surgery in children. PATIENTS: Between January 1990 and December 1991, 16 consecutive patients aged 6 days to 14 years with JET associated with significant haemodynamic impairment after cardiopulmonary bypass were treated with amiodarone as the principal antiarrhythmic drug. INTERVENTIONS: Amiodarone 5 mg/kg was administered intravenously over one hour and the same dose was subsequently infused over 12 hours. This was reviewed every 12 hours and repeated as necessary until a satisfactory heart rate and stable haemodynamics were achieved. Atrial pacing was used whenever possible to provide atrioventricular synchrony. RESULTS: Except for one patient with a JET rate of 160/min, the maximum JET rate ranged from 180/min to 245/min with a mean(SD) of 200 (20)/min. After amiodarone, the heart rates reduced to a mean(SD) of 170 (20), 164 (27), 158 (27), 157 (24), and 153 (19)/min at two, four, eight, 12, and 24 hours respectively. A reduction in tachycardia rate allowing atrial pacing was achieved in 10 patients by two hours. Haemodynamic variables improved in most patients with an increase in mean systolic blood pressure by an average of 15 mm Hg and a decrease in atrial filling pressures by an average of 3.5 mm Hg at four hours after amiodarone administration. There were three deaths: one was a moribund patient who died soon after the onset of JET and the other two deaths were not directly related to JET. COMPLICATIONS: Late bradycardia with hypotension was recorded in one patient. Asymptomatic late sinus bradycardia was seen in several others. CONCLUSIONS: Amiodarone can be used safely and effectively to control JET with haemodynamic improvement in most patients. The addition of atrial pacing confers the advantage of atrioventricular synchrony.

Adolescent↗
PubMed1992

Minimally invasive management of transposition of the great arteries in the newborn period.

This study reports on a predominantly noninvasive management program for neonatal transposition of the great arteries [TGA] incorporating balloon atrial septostomy [BAS] under echocardiographic control. BAS was performed in 25 consecutive patients presenting with TGA between April 1988 and April 1990. Structural and coronary anatomy was evaluated echocardiographically with angiographic supplementation only when additional data were required. This information was correlated, where possible, with direct anatomic findings and subsequent course. BAS was performed through the umbilicus in 17 patients (85% of patients in whom this approach was attempted). Thirteen patients did not require ventilation during BAS. There were minimal complications and satisfactory septostomies in all cases. Coronary anatomy was correctly predicted in all patients where anatomic correlation was available. Without invasive investigation 9 patients underwent neonatal arterial switch procedures and 2 underwent palliative procedures. BAS under echocardiographic control proved safe, effective, minimally traumatic and mostly possible via the umbilical vein. The umbilical vein, where patent, permitted rapid safe access for BAS. Echocardiographic diagnosis of the coronary artery, and structural and functional anatomy was reliable and allowed minimally invasive preoperative management in many patients.

Cardiac Catheterization↗
PubMed1986

Infective endocarditis in childhood.

A total of 37 cases of infective endocarditis, in children aged two days to 13 years, were seen from 1971 to 1983 at the Children's Hospital, Camperdown. Structural heart disease was known to preexist in 95%. Cyanotic congenital heart disease was present in 15 children, of whom 11 had been palliated by a systemic-to-pulmonary artery shunt. In five children, there was infection of a prosthetic valve. Identifiable precipitants of infection were rare. In particular, no child had had a preceding dental procedure within three months, while only 19% had had recent cardiac surgery. Organisms were identified by blood culture in 92%, the majority being streptococci (43% of cases) and staphylococci (27% of cases). While 59% of all organisms were penicillin sensitive, six of the seven early postoperative children were infected with organisms not sensitive to antibiotics, given for wound infection prophylaxis in the perioperative period. The overall death rate was 13.5%. Of the children infected with Staphylococcus aureus, 40% died, while no child with Streptococcus viridans endocarditis died. Of the survivors, four needed urgent valve replacement, and three had major central nervous system complications. Using these figures, a current profile of patients with infective endocarditis is presented.

Adolescent↗
PubMed1986

Accessory mitral valve tissue causing left ventricular outflow tract obstruction.

Although left ventricular outflow tract obstruction is commonly associated with congenitally corrected transposition of the great vessels, this obstruction is seldom caused by accessory mitral valve tissue. Three cases in which accessory mitral valve tissue caused left ventricular outflow tract obstruction in children are described. Two had congenitally corrected transposition and one had normally connected great vessels. The accessory leaflet tissue, which was identified by echocardiography and angiography, was attached by chordae tendineae to normally sited papillary muscles and herniated into the left ventricular outflow tract during systole. Operation was successful in these patients. The accessory valve tissue was excised via an arteriotomy in the great vessel that arose from the left ventricle. The obstructive tissue was excised close to its peripheral attachments in the outflow tract and its chordae tendineae were divided. Resection was performed without injury to the abnormally placed conduction system or to the normal valve structures.

Adolescent↗
PubMed1984

Generalized arterial calcification of infancy: three case reports, including spontaneous regression with long-term survival.

Generalized arterial calcification in infancy is a rare disorder in which death usually occurs in infancy, the diagnosis generally being made at autopsy. Three patients are reported. The diagnosis was made during life in two, enabling new information to be collected. Cardiac catheterization in one provided evidence suggesting stiffness of pulmonary and systemic arterial walls. Another is a long-term survivor with spontaneous regression of calcification. The third case, diagnosed at necropsy, was associated with endocardial fibroelastosis.

Aortic Diseases↗
PubMed1983

Intravenous verapamil in the treatment of paroxysmal supraventricular tachycardia in children.

Fifty-four spontaneous episodes of paroxysmal supraventricular tachycardia (PSVT) in 23 patients, varying in age from one day to fourteen years, were treated with intravenous verapamil according to a specific protocol. Stable sinus rhythm was obtained promptly with no side effects in 76% of episodes. There was no response in 9%; an unstable rhythm in 7.5%; and severe side effects (hypotension, sinus bradycardia and cardio-respiratory arrest) in 7.5%. All severe side effects were associated with larger than recommended doses of verapamil. Intravenous verapamil reverted 100% of all episodes of idiopathic PSVT in eight patients; 83% of episodes in five patients with congenital heart disease; and only 57% of episodes in nine patients with Wolff-Parkinson-White syndrome. It was ineffective in one neonate who had had intra-uterine SVT.

Adolescent↗
PubMed1979

Indicator dilution curves in the diagnosis of D-transposition of the great arteries in infancy.

Paired right and left atrial indicator dilution curves performed in a series of 17 patients with D-transposition of the great arteries (D-TGA) were reviewed. Taken together, the patterns obtained from patients who had trivial mixing between the pulmonary and systemic circulations were distinctive and easily recognizable. In the presence of substantial degrees of intracardiac mixing, however, the paired curves recorded become virtually identical and cannot be distinguished from curves recorded from patients with other forms of cyanotic congenital heart disease characterized by obligatory admixture. Thus paired atrial dye curves demonstrate a high degree of diagnostic specificity for the infant with D-TGA at greatest risk, normally those with a small intracardiac shunt. Such a procedure should facilitate early balloon atrial septostomy and obviate deterioration in the infant's condition due to prolonged catheter manipulation and/or angiography.

Humans↗
PubMed1977

Cardiac failure in infancy and childhood.

Cardiac failure in infants and children frequently results from pathophysiological mechanisms different from those of cardiac failure in adults. An age-based approach to aetiology is presented and attention drawn to details of management which should allow a high rate of salvage of patients who have reversible or correctable underlying conditions.

Acute Disease↗
PubMed1976

Angiographic assessment of anomalous origin of the left coronary from the pulmonary artery in infancy and childhood.

Angiographic findings in five paediatric patients with anomalous left coronary artery arising from the pulmonary artery are presented. An attempt is made to provide an angiographic rationale of some aspects of the pathophysiology and electrocardiography in this condition, and the vital importance of angiography in selecting the appropriate surgical approach is underlined.

Angiocardiography↗