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Biomedical subjects

A Garson

Publications and source records attributed to A Garson.

At least 163 records · Page 9Linked to original sources
PubMed1985

Transvenous catheter ablation of a right atrial automatic ectopic tachycardia.

A 10 year old patient with right atrial automatic ectopic tachycardia underwent successful transvenous catheter ablation after endocardial mapping. Tachycardia had been present for 7 years before ablation and associated with development of dilated cardiomyopathy. A single 50 J discharge at the point of earliest atrial activation was followed by the establishment of sinus rhythm that remains at 10 months' follow-up. This case represents the first reported successful catheter ablation of an atrial automatic ectopic tachycardia. Specific anatomic factors favoring successful ablation and improvement in technique are discussed.

Cardiac Catheterization↗
PubMed1985

Atrial flutter in the young: a collaborative study of 380 cases.

As children with cardiac disease grow older, atrial flutter becomes more prevalent. A collaborative study was performed in 19 institutions to determine the clinical characteristics of these children and the factors affecting prognosis. There were 380 patients with one or more electrocardiographically documented episodes of atrial flutter that first occurred between ages 1 and 25 years (mean age at onset 10.3). Episodes of flutter continued to occur for a mean of 2.5 years after the onset. Of the 380 patients, 60% had repaired congenital heart disease, 13% palliated congenital heart disease, 8% unoperated congenital heart disease, 8% an otherwise normal heart, 6% cardiomyopathy, 4% rheumatic heart disease and 2% other lesions. Overall, drugs were effective in eliminating atrial flutter in 58% of patients; specifically, amiodarone and digoxin plus quinidine were effective in 53%, digoxin alone in 44% and propranolol in 21%. Amiodarone was effective in seven (78%) of nine patients. Corrective surgery was performed after the onset of atrial flutter in 66 patients; in 52% the atrial flutter was easier to control or it resolved and in only 4% it was worse. At follow-up (mean 6.5 years), 83% of the patients were alive (49% without atrial flutter and 34% with atrial flutter) and 17% died (10% suddenly, 6% of nonsudden cardiac cause and 1% of noncardiac cause). Cardiac death occurred in 20% of those for whom an effective drug could not be found to eliminate atrial flutter compared with 5% of those who were treated with an effective drug (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Flutter↗
PubMed1985

Ventricular arrhythmias and sudden death in children.

In children, sudden death related to ventricular arrhythmias occurs virtually always in a patient with an abnormal heart. Therefore, children with ventricular tachycardia should be thoroughly investigated by anatomic cardiac catheterization and possibly electrophysiologic study. Sudden death may occur in a patient who had been relatively asymptomatic. This especially occurs in patients after repair of congenital heart disease. The patient may also never have had documented ventricular tachycardia, although most have had at least premature ventricular complexes on a Holter monitor recording. Finally, sudden death related to ventricular arrhythmias can often be prevented with vigorous medical and surgical therapy.

Adolescent↗
PubMed1985

Sudden death in a pediatric cardiology population, 1958 to 1983: relation to prior arrhythmias.

This review of sudden death in patients previously seen in a pediatric cardiology clinic attempts to identify factors that may have been predictive of sudden death. The denominator for these factors is unknown. For example, the number of patients with these possible risk factors who have well tolerated arrhythmias is not known. Further studies are planned to document the incidence of these factors in patients with similar lesions whom we continue to follow up. The following conclusions can be drawn from the study: More than three-quarters of the patients who died suddenly had severe limitation of activity, cardiac enlargement on chest radiograph or poor hemodynamic status at cardiac catheterization. The majority of patients who died suddenly had an arrhythmia in the 12 month period before death. A significant number of these arrhythmias developed for the first time in the year before death. The presence of arrhythmias was generally related to poor hemodynamic status in patients who died suddenly. Most sudden deaths occurred with the patient at rest and only approximately one-quarter occurred during participation in sports. Each cardiac diagnosis had its own specific profile of types of arrhythmias Conspicuously absent from the list of diagnoses were children with a normal heart and children with mitral valve prolapse.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1985

The use of exercise testing in children to evaluate abnormalities of pacemaker function not apparent at rest.

The purpose of this study was to evaluate the use of exercise testing in identifying abnormalities of pacemaker function and in confirming set parameters not apparent at rest in children with implanted atrial synchronous physiologic pacemakers. Maximal exercise tests were performed on 24 children (15 boys, 9 girls) from 4.5 to 18 years of age (median = 15) with physiologic pacemakers. The lower rate limit was observed before or following testing in 19 of 24 cases. In each case this correlated with the set lower rate limit. The upper rate limit was reached in 10 of 24 cases and was found to be lower than that programmed in one case in which a long atrial refractory period had limited the upper rate limit. Six children reached the maximum upper rate limit to which their pacemaker could be programmed. No abnormalities of atrial capture or ventricular capture occurred during exercise testing. Ventricular sensing was normal in each case. Atrial sensing was observed to be normal in 15 of the 24 cases. Two patients had decreased atrial sensing with exercise. Reversion to the "noise rate" due to myopotential inhibition was found in seven other cases. Subsequent tests on two of these children showed normal sensing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Definitive operation for refractory cardiac tachyarrhythmias in children.

A total of 114 children (age range 4 months to 18 years) underwent definitive operation for life-threatening or incessant tachydysrhythmias resulting from accessory conduction pathways (Kent bundle) (79), atrial ectopic foci (18), or ventricular ectopic foci (17). Of the patients with the accessory pathway type of supraventricular tachycardia, 63.3% (50/79) had classical Wolff-Parkinson-White syndrome whereas 36.7% (29/79) had retrograde conduction only across the pathway. Locations of the pathways were as follows: left posterior 48.1% (38/79), right anterior or lateral 27.8% (22/79), posterior septal 16.5% (13/79), anterior septal 3.8% (3/79), and both right and left 3.8% (3/79). With increasing experience, the success rate (cure of tachycardia) improved from 85% in the first 40 patients to 95% in the last 40 patients. One surgical death (1.3%) occurred secondary to a paradoxical air embolus. Atrial ectopic tachycardia was treated by cryoablation (nine), excision (one), combined excision and cryoablation (six), and atrial disconnection (two). The ectopic focus was located on the right atrial wall in 13 patients (72.2%) and cardiopulmonary bypass was required in eight (44.4%). The operation was successful in 89%; two patients with multiple ectopic foci continued to have uncontrolled tachycardia after the operation. Ventricular tachycardia presenting in the first 2 years of life was due to gross tumor in three cases (rhabdomyoma two, fibroma one) or microscopic hamartomatous change (Purkinje tumor) in five cases and was treated by excision alone or with adjuvant cryoablation. In four cases no tumor was found but the area of ectopic focus was successfully cryoablated. One child with diffuse endocardial tumor died of low cardiac output after the operation. Ventricular tachycardia in older children was localized to outflow patch aneurysms or other areas in the right ventricle following tetralogy of Fallot repair (three patients, treated by excision or cryoablation) and arrhythmogenic right ventricular dysplasia (two patients, treated by right ventricular disconnection). We conclude that mapping and operation for supraventricular tachycardia resulting from accessory pathways are predictable and curative in a high percentage of patients. Atrial ectopic tachycardias are more difficult to precisely localize but can be cured by a combination of excisional and cryoablative techniques. Ventricular tachycardia in infants is lethal and is commonly due to ectopic foci or microscopic tumors that may not be apparent on preoperative angiography or echocardiography. Electrophysiologically directed operations in these patients can be lifesaving.

Adolescent↗
PubMed1984

A family history of seizures associated with sudden cardiac deaths.

Hereditary prolongation of the Q-T interval is associated with ventricular dysrhythmias. Children with hereditary prolongation of the Q-T interval may have symptoms that seem related to a neurologic abnormality. Two families had members who had been treated with phenytoin sodium for seizures and had died suddenly when the medication was discontinued. Children in both families were found to have prolongation of the Q-T interval. A history of seizures or of seizures in the family may be an indication of hereditary prolongation of the Q-T interval.

Adolescent↗
PubMed1984

Antegrade conduction and AV node function in patients with unidirectional retrograde accessory pathways.

In 26 patients with unidirectional retrograde accessory pathways (URAP), antegrade conduction properties were evaluated. During electrophysiologic study the interval from the low septal right atrial potential to the His bundle potential (LSRA-H) in sinus rhythm (SR) was found to be less than 60 msec in 7 out of the 18 patients with left-sided URAP and in one out of two patients with septal URAP. Each of the six patients with right-sided URAP had an LSRA-H equal to or greater than 70 msec. During atrial extrastimulus testing, LSRA-H failed to prolong more than 100 msec (LSRA-H increment equal to or less than 100 msec) in four of six patients with left-sided URAP and LSRA-H of less than 60 msec in SR as well as in the one of two patients with septal URAP in whom the LSRA-H in SR was less than 60 msec. During rapid atrial pacing, we found 1:1 AV node conduction at a pacing rate of more than 200 bpm in the one patient with septal URAP and in 7 out of 14 patients with left-sided URAP who could be assessed. Three of these patients had progression from 1:1 AV conduction to 2:1 AV block without intervening Wenckebach. In conclusion, accelerated AV node conduction in SR and reduced AV node function during rapid atrial pacing or extrastimulus testing was found in 44% of our patients with left-sided or septal URAP. Since these patients are at higher risk for faster ventricular response to atrial flutter and fibrillation and for high frequency during supraventricular tachycardia, these findings were of clinical relevance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Arrhythmias in pediatric patients.

The six most common arrhythmias or conduction disturbances in children are discussed. For each arrhythmia, the electrocardiographic criteria in children, the common clinical situations in which the arrhythmias are see, the diagnostic work-up, the suggested treatment, and prognosis are presented. Throughout, the differences between children and adults are emphasized.

Arrhythmias, Cardiac↗
PubMed1984

Amiodarone treatment of critical arrhythmias in children and young adults.

The majority of sudden cardiac deaths in children occur in patients with prior arrhythmias and an abnormal heart. Amiodarone was given to 39 young patients (35 with an abnormal heart) with arrhythmias unresponsive to conventional treatment. Their age ranged from 6 weeks to 30 years with nine patients younger than 2 years of age. Atrial flutter was present in 16 patients, ventricular tachycardia in 14 patients and supraventricular tachycardia in 9 patients. The most common diagnosis (14 patients) was postoperative repair of congenital heart disease. The dose ranged from 2.5 to 21.6 mg/kg per day (mean 8.2). Elimination of arrhythmia (on 24 hour electrocardiography) occurred in 15 of 16 patients with atrial flutter, 11 of 14 with ventricular tachycardia and 5 of 9 with supraventricular tachycardia. Symptomatic side effects were: rash (three patients), headache (two patients), nausea (one patient) and peripheral neuropathy (one patient); seven patients had asymptomatic corneal microdeposits which normalized in all after the drug was discontinued. No side effects occurred in patients younger than 10 years of age. The following changed with treatment (p less than 0.05): heart rate decreased (three patients with atrial flutter and sick sinus syndrome required pacemaker implantation for bradycardia) and QTc increased; thyroxine (T4) and serum reverse triiodothyronine (T3) increased. During follow-up study (range 6 months to 3 years), 21 of the 39 patients continued to take amiodarone with complete control of arrhythmias, 9 were no longer taking the drug and 9 died (7 nonsudden and 2 sudden deaths). Amiodarone is an extremely effective treatment for infants and children with tachyarrhythmias resistant to conventional treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Ventricular dysrhythmias after congenital heart surgery: a canine model.

To examine the possible mechanisms of ventricular dysrhythmias in the presence of right ventricular hypertension and following ventriculotomy, we instrumented 6-month-old puppies. There were four groups: 1) six animals served as controls (instrumentation only); 2) six animals underwent ventriculotomy only; 3) six animals underwent pulmonary artery banding with a pneumatic vessel occluder to produce right ventricular hypertension; 4) six animals had both ventriculotomy and right ventricular hypertension. Each week for 8 wk, 24-h electrocardiograms and electrophysiologic studies were performed with the animals awake and unsedated. We attempted to induce ventricular dysrhythmias with premature extrastimuli, rapid pacing, isoproterenol, and vagal stimulation. The following "chronic" data were obtained in week 8 (p value for overall analysis of variance; values are mean +/- SD): heart rate - 126 +/- 16 beats/min (no significant difference between groups; all animals); right ventricular systolic pressure: control 26 +/- 6 mm Hg, ventriculotomy 30 +/- 3, right ventricular hypertension 65 +/- 5, ventriculotomy and right ventricular hypertension 75 +/- 18 (p less than 0.001); right ventricular end diastolic: control 4 +/- 1 mm Hg, ventriculotomy 4 +/- 3, right ventricular hypertension 11 +/- 5, ventriculotomy and right ventricular hypertension 16 +/- 7 (p less than 0.001); QRS duration: control 22 +/- 5 ms, ventriculotomy 33 +/- 7, right ventricular hypertension 44 +/- 6, ventriculotomy and right ventricular hypertension 49 +/- 4 (p less than 0.01); right ventricular apex-base interval with ventricular pacing: control 20 +/- 3 ms, ventriculotomy 34 +/- 9, right ventricular hypertension 30 +/- 5, ventriculotomy and right ventricular hypertension 31 +/- 6 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Rapid sinus tachycardia. Differentiation from supraventricular tachycardia.

Current pediatric literature suggests that in sinus tachycardia the heart rate rarely exceeds 200 beats per minute. Three infants had heart rates of 240 to 270 beats per minute in whom the diagnosis was sinus tachycardia. We report these cases and offer diagnostic and therapeutic suggestions for the clinician who encounters an infant with a heart rate between 200 and 300 beats per minute.

Anti-Bacterial Agents↗
PubMed1983

Junctional automatic ectopic tachycardia: new proposed treatment by transcatheter His bundle ablation.

Three infants with junctional automatic ectopic tachycardia (JET) were seen over an 8-month period. Each had decreased left ventricular function. Two were treated with amiodarone, which together with propranolol reduced the tachycardia rate 10 to 40 bpm, but did not result in sinus rhythm. One patient died suddenly at home, as had 50% of our patients with JET treated with conventional medication. Two patients were treated by transcatheter ablation of the bundle of His and implantation of an atrial synchronous pacemaker. Neither has had subsequent tachycardia or required drugs. One patient resumed sinus rhythm and does not use his pacemaker. The other patient has complete AV block and continues to use her pacemaker. This aggressive approach to this lethal dysrhythmia offers hope for prevention of the former bad prognosis.

Amiodarone↗
PubMed1983

Symptomatic sick sinus syndrome in children and adolescents as the only manifestation of cardiac abnormality or associated with unoperated congenital heart disease.

Sick sinus syndrome (SSS) occurs infrequently in children who have not undergone cardiac surgery. The symptoms, electrocardiograms, and electrophysiologic data in 11 patients aged 2 to 17 years who had nonsurgical SSS were reviewed. Syncope occurred in 5 patients and sinus bradycardia in 9. Sinus nodal recovery times were prolonged in 6 patients. The atrial effective refractory period was prolonged in 2 patients and the atrioventricular nodal functional or the effective refractory period, or both, was prolonged in 5 patients. Because patients with nonsurgical SSS may have abnormalities not only of the sinus node but also of the atrium and the atrioventricular node, it is recommended that patients with symptomatic SSS be evaluated by electrophysiologic study. The proper choice of antiarrhythmic drug therapy or permanent pacing procedure depends on a complete analysis of the cardiac conduction system.

Adolescent↗
PubMed1983

Induction of ventricular tachycardia during electrophysiologic study after repair of tetralogy of Fallot.

An association among premature ventricular complexes on routine electrocardiogram, elevated right ventricular systolic pressure and sudden death after repair of tetralogy of Fallot was previously reported. To examine this relation further, noninvasive, hemodynamic and invasive electrophysiologic data were studied in 27 patients who had undergone repair of tetralogy of Fallot 7 months to 21 years (mean 1.75 years) previously. Syncope, which had occurred in four patients, was not significantly related to ventricular arrhythmia on rest electrocardiogram, 24 hour electrocardiogram or treadmill test. All four patients with syncope had either nonsustained (two patients) or sustained (two patients) ventricular tachycardia induced at electrophysiologic study. His bundle to ventricle conduction interval was prolonged in two patients and Q to right ventricular apex interval was prolonged in three of the four patients. All four had abnormal anatomic or hemodynamic findings: two had a right ventricular systolic pressure of 70 mm Hg or more, one had right ventricular dysfunction with tricuspid insufficiency and one a septal aneurysm. The 9 patients with induced nonsustained or sustained ventricular tachycardia were then compared with the 15 patients without induced ventricular arrhythmias. Those with ventricular tachycardia had a greater prevalence of: more complex ventricular arrhythmia on 24 hour electrocardiogram (63 versus 0%, p less than 0.001), long His bundle to ventricle interval (44 versus 0%, p less than 0.001), right ventricular systolic pressure of 70 mm Hg or more (56 versus 0%, p less than 0.01) and reduced right ventricular ejection fraction (33 versus 7%, p less than 0.025). It is concluded that: 1) induction of nonsustained or sustained ventricular tachycardia was associated with a history of syncope; 2) all patients at risk for syncope could not be identified by routine electrocardiogram 24 hour electrocardiogram or treadmill test; 3) hemodynamic alterations may interact with intraventricular conduction abnormalities and predispose to ventricular tachycardia.

Adolescent↗