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Biomedical subjects

M Gewillig

Publications and source records attributed to M Gewillig.

At least 91 records · Page 5Linked to original sources
PubMed1995

Dopamine suppresses thyroid-stimulating hormone secretion in neonatal hypothyroidism.

The infusion of dopamine, a hypophysiotropic catecholamine, which inhibits release of thyroid stimulating hormone (TSH), is the inotropic therapy of first choice in neonatal intensive care. Newborns with primary hypothyroidism are at increased risk of cardiocirculatory morbidity and are screened by measuring serum TSH concentrations. In an infant with both congenital heart disease and neonatal hypothyroidism, withdrawal of dopamine infusion was documented to evoke a doubling of serum TSH levels within 40 min, a finding suggestive of an inhibitory effect of dopamine administration on neonatal TSH hypersecretion. As a result, dopamine therapy may be a pitfall in TSH screening for neonatal hypothyroidism.

Congenital Hypothyroidism↗
PubMed1995

Terminal deletion in chromosome region 8p23.1-8pter in a child with features of velo-cardio-facial syndrome.

A child with an atrial septal defect, hypernasal speech with an immobile soft palate, learning difficulties and behavioral problems is reported. The clinical diagnosis in this child was velo-cardio-facial syndrome (VCFS), but cytogenetic analysis showed the presence of a small terminal deletion in 8p23.1-8pter. This observation shows that deletions in 8p23 may lead to features similar to VCFS. This suggests that in patients with VCFS but without a deletion in 22q11, attention should be focussed on 8p.

Child↗
PubMed1994

ALCAPA syndrome: an example of chronic myocardial hypoperfusion?

OBJECTIVES: The purpose of this study was to evaluate functional variables and morphologic correlates of chronically hypoperfused myocardium before and after revascularization. BACKGROUND: Neonates with congenital anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA syndrome) develop some myocardial necrosis shortly after birth. The survivors of this event are left with a localized infarction and an almost entirely collateral circulation-dependent perfusion of the left ventricle that results in poor global left ventricular function. Survival beyond infancy is uncommon because of severe left heart failure. Revascularization, however, brings about functional recovery with good clinical outcome. The ALCAPA syndrome is thus characterized by chronic collateral circulation-dependent low perfusion, low contraction matching and potential revivability. METHODS: Five patients with ALCAPA syndrome are presented, with preoperative and postoperative clinical findings and histologic data obtained from intraoperative transmural biopsy specimens. RESULTS: The angiographically assessed preoperative ejection fraction was 33 +/- 19% (mean +/- SD). Postoperative echocardiographic follow-up revealed normal left ventricular function in all patients. Histologic study of the biopsy specimens taken from the region perfused by the anomalous artery showed a variable degree of fibrosis (51 +/- 32%). The ultrastructure of the remaining myocytes revealed viable characteristics, but a substantial percent (46 +/- 26%) showed a markedly reduced fraction of contractile material. CONCLUSIONS: These ultrastructural studies suggest delayed subcellular adaptive responses in the chronically hypoperfused myocardium of patients with ALCAPA syndrome.

Adolescent↗
PubMed1994

Asplenia syndrome and isolated total anomalous pulmonary venous connection in siblings.

We report on a family with asplenia syndrome in one and total anomalous pulmonary venous connection (TAPVC) in the other sib. Both conditions are rare, may have a genetic cause and belong to a spectrum of laterality disorders. This suggests that both asplenia syndrome and TAPVC in this family are the clinical expression of a single genetic disorder.

Heart Defects, Congenital↗
PubMed1994

Reliability of subjective estimates of exercise capacity after total repair of tetralogy of Fallot.

Sixty-nine patients (age 10 +/- 3.5 years, median 9.7 years) operated on for tetralogy of Fallot, underwent exercise testing 5.1 +/- 2.5 years after total correction. Aerobic capacity was assessed by the ventilatory threshold method. After the exercise test, parents completed a validated standardized questionnaire to evaluate the habitual level of physical activity of their child. They were then asked to place their child into one of three groups, describing their child's activity level, compared to normals (below average, average and above average). In the average and above-average groups, 73% and 65% of the patients were misclassified when compared to objective exercise testing. However, in the below-average group, no misclassifications were found. Subjective estimates of activity level, and consequently exercise tolerance, were poorly associated with objective measurements of exercise performance in these patient groups. Our results question the reliability of self-reported estimates of physical activity level and consequently exercise capacity in children after surgical correction of tetralogy of Fallot.

Activities of Daily Living↗
PubMed1993

Extended aortic root replacement with pulmonary autografts.

The surgical relief of complex multilevel left ventricular outflow tract obstruction remains a challenging surgical problem. We present a new operation which combines the concepts of aortoventriculoplasty, extended aortic root replacement and the use of a pulmonary autograft. Four patients underwent this operation without mortality and morbidity. All patients were in sinus rhythm and showed excellent function of the autograft valve at early follow-up. This operation might present a more durable or even a definitive solution in the management of complex left ventricular outflow tract obstructions.

Adolescent↗
PubMed1993

Cardiorespiratory exercise performance after Senning operation for transposition of the great arteries.

OBJECTIVE: To assess the cardiorespiratory response to graded exercise in patients after the Senning operation for transposition of the great arteries. DESIGN: Cross sectional study. Exercise performance was assessed by determination of the ventilatory anaerobic threshold. This was defined as the exercise intensity at which the ventilatory equivalent for oxygen (VE/VO2) started to increase systematically without a concomitant increase in the ventilatory equivalent for carbon dioxide (VE/VCO2). SETTING: Outpatient department. PATIENTS: Sequential sample of 20 patients studied 5-10 years (mean 7.3 years) after the Senning operation. Age at exercise testing varied from 5 to 11 (mean 7.8) years. RESULTS: The ventilatory threshold in the patients was significantly lower than normal (p < 0.005) and averaged 79.3% (SD 13%) and 80% (12%) of the predicted normal value for age and weight, respectively. Also, the ventilatory threshold was surpassed sooner (mean 3.2 (range 2-5) minutes) in the patients than in normal controls (3.9 (2.6-4.6) minutes). The lower ventilatory threshold was associated with a subnormal oxygen uptake (ml/min/kg) during submaximal exercise, a higher than normal ventilatory equivalent for oxygen ratio, and a lower end tidal carbon dioxide tension in the patients compared with normal controls. In half of the patients heart rate was lower during graded exercise. This relative bradycardia was not associated with a normal ventilatory threshold, as often seen in fit young people. No major disturbances in rhythm were observed during exercise. CONCLUSION: Exercise performance, assessed by respiratory gas exchange, was slightly but significantly lower than normal in patients after the Senning operation. A subnormal ventilatory threshold, associated with a higher than normal ventilatory response during submaximal exercise, supports the hypothesis that oxygen delivery to tissues is slightly impaired in these patients.

Anaerobic Threshold↗
PubMed1992

Rheologic genesis of discrete subvalvular aortic stenosis: a Doppler echocardiographic study.

To determine whether morphologic structures or abnormal flow patterns predispose to pathologic proliferation of subvalvular tissue, 26 patients (mean age 19.8 +/- 10.3 years) were studied greater than or equal to 6 months after operation for isolated discrete subvalvular aortic stenosis. The aortic root diameter and the mitral-aortic separation were measured with sector echocardiography. Flow patterns in the left ventricular outflow tract of these patients and control subjects were evaluated with a color flow mapping system optimized for the detection of turbulence. All control subjects had laminar flow throughout systole in the left ventricular outflow tract. By contrast, turbulence originating well below the site where the shelf had previously been resected was observed in 20 (77%) of the 26 patients. In 16 of these 20 patients turbulence was caused by a ridge, which in 13 patients could be identified as the offshoot of a ventricular band. In four patients the turbulence was caused by malalignment of the muscular and membranous septum, resulting in protrusion of the muscular septum into the outflow tract. Except for the latter four patients, the aortic root diameter was 84 +/- 10% of values predicted by body surface area, with values in six patients falling below the third percentile (p less than 0.01). The mitral-aortic separation was 9.7 +/- 3.5 mm, values in 21 patients falling above the 97th percentile (p less than 0.001). These data support the theory that discrete subvalvular aortic stenosis may be caused by a chronic flow disturbance, preferably in a small and long outflow tract. Left ventricular bands, if reaching the outflow tract, may be a factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Early and late arrhythmias after the Fontan operation: predisposing factors and clinical consequences.

OBJECTIVE: To study the incidence, predisposing factors, and clinical significance of arrhythmias early and late after the Fontan operation for congenital heart disease. PATIENTS AND METHODS: All 104 consecutive patients undergoing Fontan repair from 1975 to 1988 were studied retrospectively. Hospital records were reviewed for perioperative arrhythmia. Clinical information and annual electrocardiograms were available for all 78 hospital survivors during a follow up of up to 13 years (mean 3.7 years). Ambulatory electrocardiographic monitoring was performed in 67 patients (81%). RESULTS: Eleven patients (10.6%) developed a perioperative tachycardia (eight, atrial flutter; three, His bundle tachycardia). Multivariate analysis showed that raised preoperative mean pulmonary artery pressure and low aortic saturation were significant risk factors for the development of atrial flutter (r2 = 0.32, p = 0.0001) but not for His bundle tachycardia. Despite intensive medical treatment 10 of these 11 patients died. At the last visit 72 (92%) of the 78 patients were in sinus rhythm on their standard 12 lead electrocardiogram. Junctional rhythm was present in three patients, two patients had atrial flutter, and one had a paced rhythm. Ambulatory monitoring did not show important bradycardia or ventricular arrhythmias. Actuarial survival free of supraventricular arrhythmia was 82% at eight years after operation. Multivariate analysis identified older age, increased right atrial size, and raised mean preoperative pulmonary artery pressure as risk factors for arrhythmia during intermediate follow-up (r2 = 0.46, p less than 0.001). Late tachycardias, in contrast to those occurring in the perioperative period, were not associated with an increased mortality. CONCLUSIONS: Except for his bundle tachycardia in the perioperative period, early and late arrhythmias after a Fontan operation seem to be a consequence of adverse preoperative and postoperative haemodynamic function. The perioperative outcome is therefore poor even when the patient can be restored to sinus rhythm. Medical and surgical modifications to improve the haemodynamic disturbances associated with arrhythmias are therefore indicated.

Analysis of Variance↗
PubMed1992

Abolishment of chronic volume overload. Implications for diastolic function of the systemic ventricle immediately after Fontan repair.

BACKGROUND: In patients with a univentricular heart, the chronic ventricular volume overload is acutely abolished by the creation of a Fontan circuit. This results in an immediate reduction of the ventricular cavity size but also in an inappropriate degree of ventricular wall thickness, at least in the early postoperative period. The implications for the diastolic properties of the ventricle are poorly understood. METHODS AND RESULTS: A chronic volume overload through a modified Blalock-Taussig shunt was created in 10 mongrel dogs. Six weeks later, the shunt was occluded percutaneously with a detachable balloon. The left ventricular end-diastolic dimension and posterior wall thickness were measured with transcutaneous echocardiography. Digitized high-fidelity pressure tracings were used to determine the time constant of isovolumic pressure decay, tau. The isovolumic relaxation time (A2-MVO) and time to minimal left ventricular pressure (A2-LVPmin) were recorded. All variables were followed up to 1 month after occlusion of the shunt. One hour after occlusion, there was an incomplete return to baseline values of the echocardiographic left ventricular dimension (+12 +/- 8% of baseline value, p < 0.01). Despite a 31 +/- 14% (p < 0.001) increase of the posterior wall thickness after removal of the volume overload, tau or ventricular relaxation showed no change from control values. In contrast, the early filling wave was blunted, suggesting diminished ventricular suction. A2-MVO (p < 0.01) and A2-LVPmin (p < 0.05) lengthened well above baseline values for up to 1 week after occlusion of the shunt. Over the following month, the volume-induced hypertrophy regressed, and indexes of early ventricular filling resumed control values. CONCLUSIONS: We conclude that early after removal of a chronic volume overload, the resultant increase of wall thickness is not associated with impaired relaxation but that viscosity and inertia caused by the increased mass-to-volume ratio will impair early ventricular filling.

Animals↗
PubMed1991

Arrhythmias after the Fontan procedure. Comparison of total cavopulmonary connection and atriopulmonary connection.

Arrhythmia was compared between 40 consecutive patients (pts) undergoing atriopulmonary connection (APC) and 40 undergoing total cavopulmonary connection (TCPC), between 1986 and 1990. Patients were not randomized, and those undergoing APC predominantly had tricuspid atresia (57.5% versus 15%) compared with pts undergoing TCPC who had more varied and complex cardiac defects. Before surgery there was no significant arrhythmia in either group. Hospital mortality was 15/40 and 6/40 for APC and TCPC, respectively (p less than 0.05). Early after APC nine pts developed atrial flutter (AFL) and eight died, while after TCPC only two developed AFL, and neither died (p less than 0.01). Fatal junctional ectopic tachycardia occurred in one pt in each group. During follow-up (38 +/- 8.5 months after APC versus 20 +/- 10 months after TCPC), new arrhythmia was uncommon (two AFL after APC with one death versus two AFL and one supraventricular tachycardia after TCPC with no deaths). Ambulatory ECG during follow-up showed arrhythmia in two APC and six TCPC pts (p = NS). The incidence of early arrhythmia and mortality associated with early arrhythmia appears to be less after TCPC compared with APC.

Arrhythmias, Cardiac↗
PubMed1991

Risk factors for arrhythmia and death after Mustard operation for simple transposition of the great arteries.

From 1965 to 1980, 249 consecutive patients underwent a Mustard procedure for simple transposition of the great arteries. Hospital mortality was 23 of 249 (9.2%); follow-up for 24 years (mean, 11.7 +/- 6.1 yr) revealed 50 of 249 (20%) late deaths, of which seven were noncardiac, six were in the hospital, and 37 were sudden (27 patients with poor hemodynamics and 10 unexplained). Actuarial survival after 1, 10, and 20 years was 85, 75, and 67%. The instantaneous risk of death decreased rapidly after surgery but showed a second peak from 8 to 15 years postoperation. When last seen 87% were in New York Heart Association (NYHA) class I; 69% had sinus rhythm, 20% nodal rhythm, 10% atrial flutter, and 1% paced. Survival in uninterrupted sinus rhythm after 5, 10, and 20 years was 75, 62, and 47%. Nodal rhythm detected by annual ECG occurred in 69 patients. Excluding the early experience, the risk of loss of sinus rhythm was constant in time and constant throughout the experience (2.4%/yr). Atrial flutter was observed in 36 patients. Occurrence of atrial flutter was limited to two discrete surgical periods: the first operations (26 with atrial flutter of the first 50) and an ill-defined period in the middle of the experience. Patients not operated on during these two periods were very unlikely to develop atrial flutter (one of 104, p less than 0.001). As for death, the hazard function showed a bimodal curve, the second peak appearing earlier from 5 to 11 years. If nodal rhythm was noted on the yearly routine ECG, the risk for developing subsequent atrial flutter increased by a factor of 2.1 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗