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Biomedical subjects

B Friedli

Publications and source records attributed to B Friedli.

At least 73 records · Page 4Linked to original sources
PubMed1989

Ultrasound screening for congenital cardiac malformations in the fetus. Its importance for peri- and postnatal care.

Congenital cardiac malformations (CCM) are the commonest congenital anomalies. Using ultrasonography (US), the incidence of CCM in a selected group of fetuses and the impact of CCM on perinatal and postnatal care was evaluated. The indication for fetal echocardiography (F-ECHO) in 152 pregnancies was a positive family history in 61, fetal arrhythmias seen by routine obstetrical controls in 53, suspected CCM during obstetrical US in 9, growth retardation in 3 and contracted maternal factors in 6. Twenty pregnancies had no special indication. F-ECHO was performed between the 18th and the 39th gestational week. Twenty-seven cardiac malformations were found (18%), 10 of which were important; 3 succumbed at birth, 2 after surgical intervention, 1 was aborted and 4 needed intensive care at birth. Of 53 cases with arrhythmias, 3 needed special care during pregnancy: Digitalis in a case of atrial flutter, sick leave and bedrest in 2 with supraventricular tachycardia, premature delivery in 1 case with complete AV block due to an intraventricular tumor. The extremely high incidence of CCM in this group proves the need for careful fetal evaluation to detect malformations. Nowadays F-ECHO can and should be performed as early as in the 18th gestational week, allowing either to interrupt a pregnancy or to plan delivery in a well-equipped center which provides the necessary measures for these newborns.

Echocardiography↗
PubMed1989

Effect of low dose dopamine on hemodynamic and renal function in children.

The purpose of the study was to investigate the effect of low doses of dopamine in children. Fourteen cases were studied after open heart surgery. Cardiac output and renal parameters were determined under baseline conditions and under continuous infusion of dopamine 2.5 and 5 micrograms/kg/min. During the control period cardiac index was 2.62 +/- 0.19 L/min/m2, renal plasma flow was decreased at 269 +/- 41 mL/min/1.73 m2, GFR was 86.6 +/- 9.2 mL/min/1.73 m2, and filtration fraction was elevated at 37.1 +/- 1.9%. Plasma concentration of aldosterone correlated with the filtration fraction. At 5 micrograms/kg/min dopamine increased significantly cardiac output, renal plasma flow, and to a lesser extent GFR, thus decreasing the filtration fraction. At 2.5 micrograms/kg/min dopamine, increased renal plasma flow only in patients older than 5 y and had no effect on the other parameters. The increase of cardiac output in response to dopamine was abolished by propranolol pretreatment. By contrast, the hemodynamic renal response to dopamine was not altered by beta-blockade. These results indicate that 5 micrograms/kg/min of dopamine could prevent renal failure after open heart surgery in children by increasing renal blood flow and attenuating renal compensatory mechanisms.

Adolescent↗
PubMed1989

Chronotropic and inotropic supports are both required to increase cardiac output early after corrective operations for tetralogy of Fallot.

To assess the respective roles of chonotropism, inotropism, and afterload reduction in increasing cardiac index early after corrective operations for tetralogy of Fallot, we measured vascular pressures and cardiac output and evaluated left ventricular dimension changes before and after a 35% rise in heart rate over baseline. This rise was induced by atrial pacing with intact atrioventricular conduction, isoproterenol, or atrial pacing together with dobutamine. With atrial pacing, left ventricular end-diastolic diameter decreased (38.7 +/- 4.3 to 34.2 +/- 5.6 mm, p less than 0.05), the shortening fraction (ratio of the difference between left ventricular end-diastolic and end-systolic diameters to left ventricular end-diastolic diameter) remained constant, and stroke volume index was reduced (28.8 +/- 4.5 to 19.7 +/- 4.6 ml/m2, p less than 0.05). As a result, cardiac index was left unchanged. When dobutamine was added as supplemental inotropic support, left ventricular end-diastolic diameter remained constant, shortening fraction increased (30% +/- 5.4% to 36% +/- 3.3%, p less than 0.05), and cardiac index rose significantly (3.04 +/- 0.61 to 4.18 +/- 0.85 L/min/m2, p less than 0.05). Heart rate acceleration with isoproterenol, combining chronotropism, positive inotropic support, and afterload reduction, slightly increased left ventricular end-diastolic diameter, significantly raised shortening fraction, and markedly enhanced cardiac index (3.03 +/- 0.55 to 4.9 +/- 1.09 L/min/m2). Atrial pacing with intact atrioventricular conduction, as an isolated chronotropic stimulus, is not suited to increase cardiac index early after operations for tetralogy of Fallot unless additional inotropic support is simultaneously provided.

Adolescent↗
PubMed1988

[The treatment of pulmonary valve stenosis using balloon dilatation. Long-term results].

Percutaneous pulmonary valvuloplasty has been used successfully in the treatment of pulmonary valve stenosis for several years, but reports on long-term results are still sparse. We have performed pulmonary valve balloon dilatation procedures 23 times in 22 patients since February 1985; the age of the patients ranged from 2 days to 22 years. Three patients did not benefit from the procedure, in two instances because the pulmonary valve was dysplastic and once because of severe associated infundibular stenosis. These patients subsequently underwent surgery. In the other 19 patients the initial transvalvular gradient of 35 to 160 mm Hg (mean 81 mm Hg) was markedly reduced (to values ranging from 10 to 60 mm Hg, mean 31 mm Hg) rendering surgery unnecessary. There were no complications. The patients have been followed up for periods ranging from 2 months to 3 years and all are asymptomatic. Repeat measurements of the transvalvular gradient were carried out either by recatheterization or by echo Doppler 4 months to 3 years after the procedure; we have not observed restenosis and the mean gradient remained unchanged compared to the measurements immediately after valvuloplasty. Pulmonary regurgitation was uncommon and indeed appears to be less prominent than after surgical valvotomy. Thus, percutaneous valvuloplasty now appears to be the preferred treatment for pulmonary valve stenosis and open heart surgery can be avoided in most cases.

Adolescent↗
PubMed1988

Conduction disturbances after correction of tetralogy of Fallot: are electrophysiologic studies of prognostic value?

Late complete heart block may occur after correction of tetralogy of Fallot. Whether postoperative electrophysiologic studies can identify patients at risk of developing this conduction disturbance is unknown. In this study, 57 children who underwent electrophysiologic investigation after correction of tetralogy of Fallot were followed up for 1 to 13 (mean 6.5) years after the investigation. One late death and two cases of late complete heart block occurred. The late death was due to ventricular arrhythmia and not to a conduction disturbance. The cases of late heart block occurred 2 and 5 years, respectively, after electrophysiologic study, and in both cases the patient had a prolonged HV interval; in one patient progressive lengthening of the HV interval could be demonstrated at two subsequent studies 1 year apart. Another five patients with a prolonged HV interval had normally conducted sinus rhythm up to 11 years after study. Atrial pacing at increasing rates (up to the occurrence of second degree atrioventricular block) during electrophysiologic study was the best means of predicting late heart block: of three patients with block below the bundle of His occurring at pacing rates less than 180/min, two developed late complete heart block. Thus, electrophysiologic testing of the conduction system after correction of tetralogy of Fallot is useful in predicting late complete heart block and should be performed in patients with a history of transient heart block after surgery and in those with a prolonged PR interval.

Cardiac Pacing, Artificial↗
PubMed1988

Propranolol treatment in children with tetralogy of Fallot alters the response to isoprenaline after surgical repair.

When propranolol is given to prevent hypoxaemic episodes in children with tetralogy of Fallot who are awaiting operation it is advisable to continue the treatment until shortly before the induction of anaesthesia. Because catecholamines are often required to maintain adequate cardiac output after surgical correction the effect of preoperative treatment with beta blockers on the response to isoprenaline after the operation was investigated in nine children given propranolol before operation and nine who were not. They were studied three and 24 hours after cardiopulmonary bypass. The haemodynamic response to increasing doses of infused isoprenaline was monitored. Immediately after cardiopulmonary bypass the response to isoprenaline was significantly blunted in the patients who had been given propranolol before operation. Their dose-response curve lay to the right of that for patients not given propranolol, and this indicates competitive inhibition. Propranolol concentrations in the blood and myocardium correlated significantly with the heart rate response to isoprenaline. Twenty four hours after operation the isoprenaline response was similar in both groups and concentrations of propranolol in the blood were minimal or undetectable. beta Blockers given up to the time of operation significantly altered the postoperative response to catecholamines.

Blood Pressure↗
PubMed1988

[Obstructions to pulmonary ejection and restrictive interventricular septal defects].

The association of a restrictive ventricular septal defect with a pulmonary tract obstruction is rare and may cause diagnostic and therapeutic problems. The authors report their experience of such an association in 10 children. 3 had a tetralogy of Fallot (1 death), 4 a double-outlet right ventricle (2 deaths), and 3 a coarctation of the aorta with ventricular septal defect and pulmonary artery banding (no death). Prognosis depends on the type of malformation. It has improved with years because of sooner recognition of these malformations and better surgical technics and post-operative care.

Adolescent↗
PubMed1988

Valvuloplasty with trefoil and bifoil balloons and the long sheath technique.

The experimental and early clinical experience with percutaneous valvuloplasty using trefoil and bifoil balloon catheters (Schneider Shiley) and a long introducer sheath with a new back-up wire are reported. The trefoil balloon consists of three and the bifoil balloon of two angioplasty balloons mounted in parallel on a single catheter. Inflated, they form a rosette allowing for some blood flow through the spaces between the individual balloons. These small balloons are more pressure tolerant than one large balloon. The hemodynamic advantage of these balloons compared to single balloons could be demonstrated in animal experiments (healthy valves and surgically created stenoses). In 31 consecutive patients with trefoil-bifoil balloon valvuloplasty, there was no inhospital mortality. The results of trefoil valvuloplasty in twelve patients with pulmonary stenosis compared favorably to those of patients treated with single balloons. There were no technical failures or complications. There were two unsatisfactory results (severely dysplastic valve). In the aortic valve, the results with calcified stenoses were satisfactory at first but disappointing during follow-up. There were no technical failures but one of nine patients suffered an embolic myocardial infarction. In the mitral valve, there were two failures (one deficient equipment, one stroke during balloon positioning). In one case, insufficient balloon size led to an inadequate result. One patient needed surgical drainage for a pericardial tamponade. In two patients, mitral regurgitation was significantly increased. A 17F long sheath was developed to further facilitate balloon valvuloplasty. It guides the balloon catheter across the valve (and across the septum in case of the mitral valve), stabilizes it during inflation, and serves as a second pressure line to continuously monitor the transvalvular pressure gradient. It prevents bleeding at the puncture site during the intervention and presumably reduces the trauma to the artery. Because of its thrombogenic potential, heparinization of the patients is essential. The largest balloon accepted by the sheath is a 2 X 19 bifoil balloon which was the reason to use a bifoil balloon in some mitral valves. Trefoil balloons put in place through a long sheath provide some theoretical advantages over conventional single balloons introduced over guidewires that need to be evaluated by larger clinical studies. Although they do not prevent circulatory collapse during initial inflation in tight stenoses, they permit transvalvular flow when fully unfolded.

Aged↗
PubMed1987

[Results of quantitative Doppler echocardiography in the diagnosis of cardiac malformations in children].

To assess the reliability and precision of quantitative data obtained by pulsed and continuous echocardiography in congenital cardiac malformations, we have examined 113 children aged 1 week to 17 years 5 months. 91 patients presented with right ventricular outflow tract obstructions (13 valvular pulmonary stenoses, 78 complex cardiac lesions); in 9 a left ventricular outflow gradient and in 13 an aortic coarctation was present. The measurement obtained by the Doppler method were compared to those obtained within 24 hours during cardiac catheterization. Furthermore, in 25 patients without shunt (essentially rheumatic valvulopathies) measurement of cardiac output by pulsed Doppler has been compared to measurements obtained by dye dilution curves with Cardiogreen.--The correlations between Doppler values and measurements taken during cardiac catheterization were excellent for straight pulmonary stenoses (r2 = 0.94) and even for right ventricular outflow gradient in complex anomalies (r2 = 0.93); it was slightly less good for the aortic stenoses (r2 = 0.80) and disappointing for the gradient across the coarctation (r2 = 0.50). Calculation of cardiac output in the pulmonary artery or the aorta by pulsed Doppler shows a good correlation with the results obtained by dye dilution curves with Cardiogreen (r2 = 0.75). It is concluded that the precision of Doppler measurements is excellent in pulmonary stenoses and satisfactory in the aortic stenoses. Hence in many cases an invasive procedure by catheterization can and should be avoided.

Adolescent↗
PubMed1987

Electrophysiologic effects of intravenous verapamil in children after operations for congenital heart disease.

To assess the effect of verapamil in children with congenital heart disease after surgical correction, an electrophysiologic study was undertaken in 19 patients, 0.8 to 15 years old. Atrial pacing and programmed atrial extrastimulation were performed before and 5 mn after intravenous administration of verapamil. A significant increase in conduction time and refractory periods was observed at the atrioventricular node level. Dual or accessory atrioventricular pathways, present in 14 cases, appear to have been suppressed in 9. The effect on the sinus node was of particular interest: The corrected sinus node recovery time was strongly prolonged by verapamil in 6 patients, 5 of whom had undergone surgery with extensive atrial reconstruction (Senning 2, anomalous pulmonary venous return 3) and 1 of whom had undergone correction of tetralogy of Fallot. Additional effects of verapamil were the disappearance of a sinus node entrance block in 8 patients and emergence of an ectopic pacemaker in 6. Although verapamil has electrophysiologic properties that should make it a useful drug in the treatment of reentry tachycardia, caution is indicated after extensive atrial surgery because sinus node depression may occur.

Adolescent↗
PubMed1987

Frequency of ventricular late potentials and fractionated right ventricular electrograms after operative repair of tetralogy of Fallot.

This study was conducted to assess the incidence of abnormalities of ventricular depolarization in sinus rhythm after repair of tetralogy of Fallot and their relation to spontaneous ventricular arrhythmias. Forty-four patients were studied, 10 before surgery (mean age 6.9 years) and 34 after repair (mean age 8.1 years, mean age at surgery 6.5 years, mean interval between surgery and evaluation 11 months). Evaluation was performed by means of body surface and intracavitary signal-averaging techniques, by recording local right ventricular (RV) electrograms at several sites and by 24-hour Holter monitoring (n = 28). No electrophysiologic abnormality was observed in children before surgery. Ventricular late potentials were detected in 18 patients (53%) after repair. Body surface detection of ventricular late potentials was frequently masked by the postoperative right bundle branch block pattern. Local RV electrograms were fractionated in 11 cases (32%) (mean duration 103 +/- 33 ms), most often in the RV outflow tract (n = 9), but no relation was found between fragmentation of RV electrograms and the presence of ventricular late potentials. Spontaneous ventricular arrhythmias occurred in 12 children after repair (43%), but were complex in only 4 patients (14%). There was no correlation between spontaneous ventricular arrhythmias and the presence of ventricular late potentials, presence of fractionated RV electrograms, presence of a proximal right bundle branch block or postoperative hemodynamic status.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1987

Prosthetic heart valve replacement in children. Results and follow-up of 273 patients.

We report the results and long-term follow up in 273 children (aged 2 to 16 years) who underwent prosthetic valve replacement. Mechanical valves (mostly Starr-Edwards) were used in almost all, and in 62 children more than one valve was replaced. Operative mortality was 4.7%. Actuarial survival curves (including hospital mortality) indicate a 86% survival rate at 5 years and 75% at 10 years. For isolated mitral valve prostheses (the largest subgroup), the figures are 87% at 5 years and 82% at 10 and 15 years. The main complication was thromboembolism, which occurred at a linearized rate of 2.7 per 100 patient-years. Actuarial curves indicate that 88% of patients are embolus free at 5 years, and 77% at 10 years. No patient with aortic valve replacement only had an embolism. Five of eight tricuspid prostheses thrombosed. Patients given aspirin and dipyridamole only did not have a higher rate of thromboembolic events than those given warfarin. There were five cases of endocarditis (two fatal) and four of dehiscence. No patient so far has needed replacement of a prosthesis because of somatic growth. Thus valve replacement can be performed with low mortality in children, and with satisfactory long-term survival. Thromboembolism remains a significant problem, although it appears to be less common than in adults. In this study, treatment with antiplatelet drugs only did not carry a higher rate of thromboembolic events than did treatment with warfarin.

Actuarial Analysis↗
PubMed1986

[Trefoil balloon, a new instrument for percutaneous valvuloplasty].

Complete obstruction of blood flow during balloon inflation is a major problem of percutaneous balloon valvuloplasty. To ensure continued transvalvular blood flow the authors have developed the "Trefoil balloon" consisting of three identical angioplasty balloons mounted on a single catheter. The Trefoil balloon was tested in the aorta and aortic valve in 4 dogs and produced a pressure gradient from 5 to 40 mm Hg where conventional balloons were completely occlusive. The Trefoil balloon was then used in 3 children with congenital valvular stenoses (2 pulmonary and 1 aortic stenosis). The immediate results of these valvuloplasties were satisfactory. Continued flow during balloon inflation was documented by right ventricular injection of contrast medium in the cases of pulmonary stenosis and by a systolic aortic pressure of 75 mm Hg during balloon inflation in the case of aortic stenosis. The Trefoil balloon is a promising new device for percutaneous valvuloplasty.

Angioplasty, Balloon↗
PubMed1986

[Tetralogy of Fallot: long-term evolution following corrective surgery].

To evaluate the immediate and long term results of complete correction of tetralogy of Fallot (TF), we have reviewed the records of 275 children operated on in Geneva between 1972 and end 1984. The average age at operation was 6 7/12 years (range 7 months to 16 years). Postoperative follow-up ranged from 1 year to 12 years (average 3 7/12 years). The survival rate, taking into account immediate postoperative mortality, was 90 +/- 2% after one year, 88 +/- 2% after 5 years and 88 +/- 2% after 11 years for the entire patient group. The total mortality of 9.8% has markedly decreased in recent years (14.5% before and 5.7% after 1978). Mortality is highest within the first 30 days after the operation (20 cases, 7.3%). Mortality was higher after previous palliative surgery (5/51) and for children who had to be reoperated for a residual lesion (4/23). Once the first postoperative year has passed, mortality is low: 2 deaths occurred between 1 and 2 years, and one between 2 and 5 years after the operation. Cardiac catheterization in 218 patients between 2 months and one year after surgery showed severe residual pulmonary stenosis in 4 children which made reoperation necessary; a second operation was needed for a large left-to-right shunt in 5 cases, and because of a ventricular septal defect with residual pulmonary stenosis in 6 others. Pulmonary insufficiency was noted in 106 cases (38.5%) but only 3 children showed right heart insufficiency. One child underwent pulmonary valve replacement by Björk-Shiley prosthesis. It can be concluded that a child with surgically treated TF has excellent long term survival, and that life threatening complications after the first postoperative year are rare.

Adolescent↗
PubMed1986

Trefoil balloon for percutaneous valvuloplasty.

A new balloon (Trefoil balloon) was developed to avoid complete interruption of blood flow during percutaneous balloon valvuloplasty. It consists of three identical 2- to 4-cm-long angioplasty balloons mounted in a parallel fashion on a single catheter. Filled simultaneously, they assume the cross section of a rosette, allowing for continued blood flow. Trefoil balloons of various sizes were tested in five dogs (aorta and aortic valve). They created a gradient ranging from 5 to 40 mmHg where conventional, single balloons of comparable size were completely obstructive. In three consecutive patients with congenital pulmonary stenosis, Trefoil balloons were used successfully and without significant complications. Continued transvalvular blood flow during the actual dilatation process was documented in all cases. The Trefoil balloon is a promising new device for percutaneous valvuloplasty and, perhaps, coronary angioplasty.

Adolescent↗
PubMed1986

Trefoil balloon for aortic valvuloplasty.

A new balloon for valvuloplasty (Trefoil balloon) was successfully used in a 12 year old boy with congenital aortic stenosis. The Trefoil balloon consists of three angioplasty balloons mounted in parallel on a single shaft. When they are inflated simultaneously they produce a rosette that allows blood flow to continue through the valve. The aortic pressure only dropped to 75 mm Hg during a 15 s balloon dilatation at 4 bar (400 kPa). The procedure reduced the transvalvar gradient from 45 to 15 mm Hg.

Angioplasty, Balloon↗