Biomedical subjects
Publications and source records attributed to H Singer.
Intralobar lung sequestration in a 5-month-old dyspnoeic infant was diagnosed by colour-coded Doppler sonography (CDS). Grey scale imaging showed an echogenic mass adjacent to the right hemidiaphragm. CDS demonstrated an abnormal arterial blood supply via a vessel originating from the descending aorta at the level of the diaphragm.
Twenty-one cases (13 male, eight female) of atrial automatic tachycardia (AAT) assessed by standard and Holter-ECG in otherwise healthy infants and children have been documented. AAT was incessant in 12 patients, repetitive in seven, and of undetermined type in the remaining two. The frontal P wave axis suggested an ectopic focus in the high right atrium or right atrial appendage in 13 patients, in the low right atrium in one patient, and in the left atrium in seven patients. Thirteen out of 14 patients with the incessant or undetermined type of AAT were symptomatic, in contrast to only two of seven patients with the repetitive type. All patients were treated with between one and eight (median three) antiarrhythmic drugs. The most effective drug was amiodarone, followed by the class I C antiarrhythmic drugs, propafenone and flecainide. At present, all patients are alive 4 months to 21 years (median 2.5 years) after diagnosis of AAT. Twelve patients are in sinus rhythm, five of them without any medication. Nine patients still have AAT, which, however, is repetitive or intermittent in all but one. In conclusion, AAT is an unusual, and in its incessant form often severely symptomatic arrhythmia, which is resistant to conventional antiarrhythmic medication. However, amiodarone and class I C antiarrhythmic drugs are frequently effective. Since medical treatment with these drugs is often successful, and AAT may resolve completely, a conservative approach is indicated in many cases.
The pulmonary and systemic flow (Qp/Qs) and resistance ratios (RP/Rs) were determined in children with isolated ventricular septal defects (VSD) to derive an "effective defect resistance" (Rd/Rs) representing the ratios of the resistance of the defect to the systemic vascular resistance. The defect size (expressed as the ratio of the area of the defect to the cross-sectional area of the ascending aorta) was related to the calculated "effective defect resistance," where a significant (non-linear) correlation was found. The effective resistance of the defect is a useful aid for estimation of the anatomical size of a ventricular septal defect. The close correlation between anatomical size and the hemodynamic parameter Rd/Rs allows one to calculate the ratio Rp/Rs with this concept using noninvasive Doppler-ultrasound and echocardiography. This was performed in 21 children with VSD who underwent cardiac catheterisation. The noninvasive calculated flow ratio Qp/Qs and the resistance ratio Rp/Rs showed a close correlation to the values measured at cardiac catheterisation.
The doppler-sonographic examination of flow velocities in intracerebral arteries is of central importance in the diagnostic evaluation of potential neurologic complications in intensive care patients. Furthermore pulsed Doppler-sonography can assess the hemodynamic consequences of several congenital heart defects (e.g. the ductus arteriosus Botalli). Characteristics of the normal flow profile in the intracranial arteries are the systolic and diastolic forward flow caused by the "Windkessel" function of the aorta. Well known pathologic flow profiles (systolically and diastolically increased flow velocities, diastolically decreased flow velocities and diastolic retrograde flow) occur in neurologic and cardiovascular diseases. We have investigated three children after cardiac surgery, who showed a presystolic increase in the flow velocities, which is clearly different from the flow profiles mentioned above. In our opinion, this abnormal flow pattern is due to a decreased ventricular output in combination with an elevated central venous pressure in these patients.
A congenital subclavian steal syndrome may be caused by coarctation or interruption of the aortic isthmus or by isolation of a subclavian artery. We describe a patient with D-transposition of the great arteries, a left aortic arch, and isolation of the right subclavian artery which originated from the right pulmonary artery via a right ductus arteriosus. A subclavian steal syndrome was demonstrated noninvasively by echocardiography and doppler sonography of the cerebral arteries. We recommend routine cerebral doppler sonography for all infants with congenital heart disease and unilaterally weak brachial pulses. Since the long term outcome of the congenital subclavian steal syndrome is uncertain the aberrant subclavian artery should be reimplanted at the time of corrective cardiac surgery.
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We report on a neonate with multiple cardiac rhabdomyomas, including a huge rhabdomyoma of the left ventricular posterior wall. Prenatal ultrasonography performed because of supraventricular tachycardia led to the diagnosis in the 28th week of gestation. Postnatal echocardiography confirmed the prenatal diagnosis. The tumor could not be removed surgically and the child died as a result of intractable arrhythmia at the age of 5 days. The diagnosis of multiple cardiac rhabdomyomas was confirmed by autopsy.
The case of a male child is reported in which the syndrome of absent pulmonary valve and ventricular septal defect was associated with anomalous drainage of the right superior pulmonary vein into the superior vena cava, atrial septal defect, a right aortic arch, and an aortic isthmic coarctation. The combination of aortic coarctation with a high degree of right-ventricular outflow obstruction has not been reported so far in the literature. This case shows that there is no proof of aplasia of the ductus arteriosus in the syndrome of absent pulmonary valve and ventricular septal defect. Most likely, there is an early involution of the ductus arteriosus; persistence of the ductus arteriosus would not be compatible with fetal survival.
In two newborns with severe coarctation of the aorta and interrupted aortic arch, subclavian-steal was shown by angiocardiography. In both children pulsed doppler recordings were obtained in the cerebral arteries: normal forward flow during systole and diastole could be shown in the anterior cerebral arteries, both internal carotid arteries, the basilar artery and the right vertebral artery. In the left vertebral artery in both infants a negative flow indicating backflow from the brain could be shown. Pulsed doppler sonography of the flow in the vertebral arteries is a non invasive method for diagnosis of subclavian steal in infants with coarctation of the aorta and interrupted aortic arch.
A true diverticulum of the ventricle is a very rare congenital cardiac lesion which is characterized by a normal myocardial wall and active participation in the ventricular contractions. Diverticula of the right ventricle may originate from the apical or anterosuperior wall. We report three patients with an anterosuperior diverticulum of the right ventricle associated with a perimembranous ventricular septal defect, one of whom additionally had obstruction of the right ventricular outflow tract. These patients presented clinically with symptoms related only to their associated defects. The right ventricular diverticulum was diagnosed by angiography in all, but was also seen on cross-sectional echocardiography in one patient. The ventricular septal defect was repaired through an incision of the diverticulum, which was reduced in size at the same time. Complete resection appears necessary only if severe endocardial fibrosis is present within the diverticulum, because such a diverticulum does not contribute to right ventricular contraction, but rather is at risk of rupture.
We present a model based on an electric analogon that describes the haemodynamic situation of an isolated ventricular septal defect. The model shows a way to estimate the ratio of pulmonary to systemic vascular resistance by Doppler sonographic measurements of pulmonary to systemic flow ratio (Qp/Qs) and the ratio between the size of the defect and the cross-sectional area of the aorta (Av/Aa). The ratio of pulmonary to systemic vascular resistance is theoretically given by: Rp/Rs = Qs/Qp + log (Av/Aa) * (1-Qs/Qp). Systemic to pulmonary flow ratio can be measured by Doppler echocardiography as well as Av/Aa; therefore, Rp/Rs can be estimated noninvasively by the equation given above. The values estimated noninvasively by Doppler echocardiography showed a good correlation with the haemodynamic data obtained at cardiac catheterisation.
Rhabdomyomas are benign cardiac tumors often occurring as multiple lesions. We describe an infant with multiple cardiac rhabdomyomas causing severe right-ventricular and left-ventricular outflow tract obstructions. The intracavitary parts of the rhabdomyomas were successfully resected when the patient was 5 weeks old. Echocardiography showed regression in size of the remaining intramural tumors. Since there is only a low growth potential in cardiac rhabdomyomas, surgical management is indicated only in patients with hemodynamic obstruction or significant arrhythmias. Surgery should be primarily directed to relieve hemodynamic obstruction. If complete resection is not possible without damage to vital structures, resection should be restricted to the intracavitary parts of the tumor.
This is a report on two mentally retarded sibs with similar anomalies (sagittal craniosynostosis, complex cardiovascular malformations, mandibular ankylosis) and various dysmorphic features. They could represent a "new" probably monogenic syndrome.
A female infant presented with signs of general muscle hypotonia and increasing hypertrophy of the heart muscle. There was a constant lactic acidosis worsened after glucose intake. Serum lactate levels were increased up to 6.7 mmol/l. Serum alanine levels reached maximum concentrations of 2,800 mumol/l. The patient died after sudden cardiac arrest at 22 months of age. Histology of the heart showed the pattern of foamy myocardial transformation with accumulation of mitochondria and an increased glycogen content. Biochemical analysis of the skeletal muscle and the heart demonstrated signs of a disturbed respiratory chain. The content of cytochrome aa3 protein was decreased in skeletal muscle and heart mitochondria. It is suggested that respiratory chain defects may be the cause of foamy myocardial transformation of the heart.
The antibiotic moenomycin is a valuable biochemical tool for studying the metabolism of peptidoglycan and the autolytic system in Escherichia coli, since as a specific inhibitor of peptidoglycan polymerases it can efficiently promote cell lysis. In liquid media the bacteriolytic effect on E. coli K12 was dependent on the concentration of moenomycin, on growth phase and on growth rate. Before lysis cells underwent major morphological alterations. In sucrose-containing medium complete transformation to osmotically sensitive spheroplasts was easily achieved by addition of moenomycin. The minimum inhibitory concentration of the antibiotic varied with the strain of E. coli and was highly dependent on the growth medium. A tritiated derivative of moenomycin, [3H]decahydromoenomycin A, was prepared and found to have the same inhibiting efficiency. Its binding to E. coli membranes and membrane proteins was investigated. The absence of irreversible binding suggested that moenomycin might be a competitive inhibitor of the peptidoglycan polymerases. Spontaneous moenomycin resistant variants were isolated at a frequency of about 10(-9).
From 1970 to 1986, 43 patients with pulmonary atresia and ventricular septal defect (PA-VSD) were diagnosed in our hospital. 19 children had a collateral lung perfusion via a ductus botalli (DB), three children had a DB and systemico-pulmonary collateral arteries (SPCA), and 21 children had only SPCA. Patients with a DB alone had significantly larger pulmonary arteries. Children with SPCA always had hypoplastic pulmonary arteries and intrapulmonary arborization anomalies and in a high percentage (19 patients) they showed intrapulmonary stenoses. 26 palliative operations were performed in 24 children. After palliative operations in 15 cases (patients with DB: RVOT-Patch: one patient, aortopulmonary shunt: three patients, Brock procedure: one patient, patients with SPCA: RVOT-Patch: five patients, aortopulmonary shunt: four patients, Brock procedure: one patient) we checked the possibility of corrective surgery with the equation of Alfieri. According to this equation, corrective surgery without excessive right ventricular pressure would have been possible in all post-operatively catheterized patients with DB after primary palliative operations but, due to the pulmonary artery anomalies, only in seven out of nine patients with SPCA (one patient of the latter group was operated twice, Brock procedure and RVOT-Patch). In four cases we could prove the value of the Alfieri equation after corrective operations. There was an excellent correlation between the predicted relation of PRV/PLV and the actually measured pressures. In our opinion, the Alfieri equation forms a valuable aid in the preoperative assessment of children with PA-VSD.
Pulsed doppler recordings were obtained in the truncus coeliacus in 12 premature born infants (gestational age 30.3 +/- 2.5 weeks) with the clinical signs of patent ductus arteriosus Botalli (PDA) and compared to a control group of 24 healthy infants (gestational age 40.5 +/- 5.3 weeks). In all children the maximal systolic velocity, the endsystolic and the enddiastolic velocity and the pulsatility-index were measured. The 24 healthy newborns showed the following velocities: Maximal systolic velocity: 77 +/- 16 cm X s-1; endsystolic velocity: 31 +/- 10 cm X s-1; enddiastolic velocity; 18 +/- 9 cm X s-1. The pulsatility-index was 0.75 +/- 0.11. In children with PDA the maximal systolic velocity was 72 +/- 21 cm X s-1, the endsystolic velocity 15 +/- 14 cm X s-1 and the enddiastolic velocity -5 +/- 8 cm X s-1. The pulsatility-index was 1.08 +/- 0.12. All infants with large PDA showed a significant decrease of the endsystolic velocity and enddiastolic velocity, whereas the pulsatility-index was significantly increased. The decrease of the endsystolic and enddiastolic velocity in infants with large PDA in comparison to the healthy control group may lead to hypoxemic-ischemic lesions of the intestinal organs. The increased incidence of necrotizing enterocolitis in premature infants with large PDA may be the result of hypoperfusion of the small bowel.
A case of mitral atresia with normal aortic valve, situs solitus, d-loop, ASD, VSD, DORV and atresia of the pulmonary valve is presented. Systemic-pulmonary collateral arteries were the single source of collateral lung perfusion. These vessels are often found in patients with tetralogy of Fallot and pulmonary atresia with VSD. The case favours the idea that these vessels are not specific for the above mentioned cardiac anomalies. It supports the theory that they represent true embryonal vessels which can persist in cases of an inadequate or completely missing connection of the sixth aortic arch derivates with the pulmonary vascular bed.