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M Tynan

Publications and source records attributed to M Tynan.

At least 91 records · Page 5Linked to original sources
PubMed1986

Measurement of plasma disopyramide as a guide to paediatric use.

We have studied the relationship between age, daily dose, plasma concentration and clinical efficacy of disopyramide in a group of paediatric patients. Twelve children with ventricular and 3 with supraventricular arrhythmias were treated with oral disopyramide. The initial dose was 3-6 mg/kg per day. This was adjusted until a pre-dose plasma concentration greater than 2 mg/I was achieved. Seven patients were judged to have responded to the treatment on clinical criteria. No symptoms or signs of toxicity were observed. In some of the children the dose of disopyramide required to achieve a plasma concentration greater than 2 mg/l was greatly in excess of the normal adult dose. Generally the youngest children required the highest dose, but the variation was wide. The dose could not be predicted from the age, the body weight or the surface area of the patient. In children high doses of disopyramide may be needed to achieve effective plasma concentrations of the drug; such doses are not associated with adverse effects. Measurement of the plasma concentration is necessary to guard against premature termination of therapy.

Administration, Oral↗
PubMed1985

Percutaneous balloon pulmonary valvuloplasty.

Percutaneous pulmonary valvuloplasty was performed in 27 patients with congenital pulmonary valve stenosis. A fall in the transvalve gradient of at least 15 mm Hg occurred in 22 patients. In five there was little change in the severity of the stenosis; in three of these the pulmonary valve was dysplastic. None of the successfully treated patients had a dysplastic valve. The two other failures, early in the series, were probably due to inadequate balloon size. In one patient the procedure was performed twice, with a successful result from the second dilatation with a larger balloon. Follow up studies in a further six patients showed no evidence of restenosis in those who had been successfully treated and no late improvement in the remainder. There were no important complications. Percutaneous pulmonary valvuloplasty should be the initial treatment for congenital pulmonary valve stenosis, although when the valve is dysplastic the result is less likely to be satisfactory.

Adolescent↗
PubMed1985

Aortic coarctation in the first three months of life. An anatomopathological study with respect to treatment.

Operation for coarctation in infancy is a lifesaving procedure, but it still carries a high mortality and is followed frequently by recurrence of stenosis. This is especially true when the procedure is performed in the first 3 months of life. To determine a correlation, if any, between anatomy of coarctation and surgical procedures, we have studied a series of 42 autopsy specimens from patients younger than 3 months who had aortic coarctation. We found that concepts of coarctation based solely on a discrete lesion or isthmic hypoplasia were simplistic. The anatomy was much more complex, the findings being relevant to surgical techniques currently in use (resection and end-to-end anastomosis, subclavian flap aortoplasty). Of equal significance in the cases we studied to the presence of a shelf of ductal tissue within the aortic lumen or hypoplasia of a segment of the arch was the finding of "waist" lesions. In these cases the wall of the aorta was constricted to form the obstruction. Such "waists" coexisted with discrete shelves or with shelves and isthmic narrowing. While we recognize the danger of extrapolating from autopsy findings to predict clinical results, our observations suggest that surgical procedures might best be tailored to the precise anatomy present. It seemed that in may cases a subclavian flap procedure offered the best chance of success. Cases with anatomy suitable for resection and end-to-end anastomosis were less frequent. Percutaneous angioplasty seemed at best to offer only palliative options in limited cases.

Age Factors↗
PubMed1984

The univentricular atrioventricular connection: getting to the root of a thorny problem.

Most hearts described as "single ventricle" or "univentricular heart" possess 2 ventricular chambers, even though 1 is usually described as an "outlet chamber." This stems from the wide acceptance that the criterion of a single ventricle is the presence of a double-inlet atrioventricular (AV) connection. In recent years, using this criterion, an attempt was made to show how hearts with double-inlet right ventricle or "classic tricuspid atresia" were (in terms of ventricular morphology) just as univentricular as "single ventricle with outlet chamber." This attempt brought still further confusion to an already contentious topic. The root of the problem clearly is the injudicious use of the adjective "single" or "univentricular." Conventionally it is used to describe the ventricular mass. In most hearts with double-inlet connection it is not the ventricles that are univentricular; it is the AV connection. The concept of a univentricular AV connection, then, appropriately groups hearts with double-inlet along with those having absence of 1 AV connection. It distinguishes this entire group from those other hearts with biventricular AV connections (each atrium connected to its own ventricle). The term "univentricular AV connection" is thus a collective one for all those hearts in which the atria connect to only 1 ventricle. Confusion will be completely removed if individual hearts are described for what they are in terms of AV connection and ventricular morphology (for example, double-inlet left ventricle with rudimentary right ventricle rather than single ventricle with outlet chamber).

Heart Atria↗
PubMed1984

Evaluation and treatment of fetal arrhythmias.

In a series of 31 cases referred for the evaluation of fetal arrhythmia, it was possible to identify the rhythm disturbance correctly using M-mode echocardiography. Cross-sectional echocardiography delineated structural abnormality where it occurred in association with an arrhythmia. Fifteen cases had premature atrial or ventricular contractions occurring in structurally normal hearts. These were not associated with perinatal mortality or morbidity in our series. Nine cases had complete heart block, three of which had structural cardiac anomalies. Seven cases were of atrial tachycardia, six were treated prenatally, one was delivered prematurely. Correct identification of an arrhythmia and appropriate prenatal therapy where indicated, was found to prevent unnecessary operative or premature deliveries.

Arrhythmias, Cardiac↗
PubMed1984

Evolution of coarctation of the aorta in intrauterine life.

The echocardiographic appearances in a case of coarctation of the aorta, first suspected at 21 weeks of intrauterine life, changed progressively during this time. Early right ventricular hypertrophy and increasing aortic arch hypoplasia were evident and suggest the possible sequence of evolution of the coarctation in this case.

Aortic Coarctation↗
PubMed1983

Transcatheter occlusion of a Blalock-Taussig shunt with a detachable balloon in a child.

A case of transcatheter occlusion of a Blalock-Taussig shunt with a detachable silicone filled balloon is described. This 11 year old boy had previously had a repair of tetralogy of Fallot together with ligation of a large Blalock-Taussig shunt. Though there was a good surgical result, the shunt proved to be incompletely closed leaving a significant left to right shunt. As an alternative to a further operation a silicone filled balloon was detached in the Blalock-Taussig shunt and this successfully closed the fistula.

Angioplasty, Balloon↗
PubMed1983

Evaluation of fetal arrhythmias by echocardiography.

The normal fetal heart shows variation in rate and rhythm. Twenty three cases that fell outside the normal patterns of variation of heart rate and rhythm were evaluated by echocardiography. Ten showed atrial or ventricular extrasystoles and these were not associated with perinatal morbidity or mortality. Seven cases showed complete heart block, two in association with structural cardiac abnormality. Six cases were of supraventricular tachycardia, five of which were successfully treated and one was delivered prematurely. It was possible to diagnose accurately the type of arrhythmia using the M-mode echocardiogram to compare the relation between atrial and ventricular contraction. Cross-sectional echocardiography allowed identification of associated structural abnormalities. Recognition that an arrhythmia is present and appropriate prenatal treatment if this is indicated will avoid unnecessary operative or premature deliveries.

Arrhythmias, Cardiac↗
PubMed1983

The feasibility of fetal echocardiography in the prediction of congenital heart disease.

The fetal heart has been studied echocardiographically in over 750 pregnancies between 16 weeks gestation and term. This has allowed description of normal fetal cardiac anatomy, the acquisition of measurement data for various cardiac structures and the detection of 16 cardiac malformations. In all the patients delivered so far and in which normality was predicted the neonatal heart was confirmed to be normal (640) except in 3 early cases where defects were overlooked. This promises to be a useful technique for the reliable prediction of structural cardiac anomaly prenatally.

Echocardiography↗
PubMed1982

Subxiphoid M-mode echocardiography in atrioventricular defects.

M-mode echocardiograms obtained using the subxiphoid position of the transducer were compared with those obtained using the parasternal position in 21 children with atrioventricular defects. In the 16 children with complete atrioventricular defect, it was always possible to demonstrate a common valve orifice wholly occupying the space between the anterior and posterior cardiac walls with no interventricular septal tissue in the plane of the orifice. Scanning between the plane of this orifice and the ventricular cavity demonstrated a ventricular septum in all cases, separating components of the atrioventricular valve apparatus from each other, corroborating the impression that the valve was straddling the ventricular septum and, therefore, that the valve was common to both ventricles. No septal tissue was detected in scans ranging between the aortic valve and the common orifice in these 16 children. In the five children with partial atrioventricular defects, two atrioventricular orifices separated by septum could be demonstrated. The subxiphoid approach in these 21 children defined the anatomy of atrioventricular defects more clearly and more readily than the parasternal approach.

Child, Preschool↗
PubMed1982

Balloon atrial septostomy under two dimensional echocardiographic control.

Two dimensional echocardiography has been used to guide balloon atrial septostomy in five cases of transposition of the great arteries. A single lumen balloon catheter was used. The catheter can be accurately located within the left atrium before inflation of the balloon, thus avoiding some of the traumatic accidents possible during septostomy. The balloon can be observed creating the atrial defect and the approximate size of the resulting defect noted. It can also be seen if the foramen ovale is only being stretched and not torn. The use of the two dimensional echocardiogram during septostomy should significantly contribute to the speed, efficiency, and safety of the procedure.

Echocardiography↗