Arrhythmias after cardiac transplantation.
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INTRODUCTION: A functional region of slow conduction located in the inferior right atrium has been postulated to be critical to the induction and maintenance of typical human atrial flutter. We reexamined the potential role of functional conduction delay in the annular isthmus between the tricuspid valve and the inferior vena cava; it is within this region that such delays have been postulated to occur, and where interruption of conduction by radiofrequency energy application has been shown to eliminate typical flutter. METHODS AND RESULTS: Thirty patients with type I atrial flutter (30 counterclockwise, 14 clockwise) were studied. Counterclockwise and clockwise isthmus activation times adjacent and parallel to the tricuspid valve were measured during three conditions: (1) atrial pacing in sinus rhythm, (2) atrial flutter, and (3) entrainment of atrial flutter. During pacing in sinus rhythm at progressively shorter cycle lengths, both counterclockwise and clockwise isthmus activation times remained unchanged; decremental conduction prior to flutter induction or loss of capture was not observed. Counterclockwise isthmus activation time did not significantly differ during flutter (68 +/- 23 msec), inferolateral tricuspid annulus pacing (71 +/- 23 msec), or entrainment of flutter (72 +/- 23 msec). Similarly, clockwise isthmus activation times did not significantly differ between flutter (65 +/- 22 msec), proximal coronary sinus pacing (73 +/- 21 msec), or entrainment of flutter (64 +/- 15 msec). CONCLUSION: Decremental conduction is not characteristic of activation through the isthmus when activation is assessed parallel and adjacent to the tricuspid annulus. Functional slowing or conduction delay does not develop in this region during typical atrial flutter.
The present status of the use of electrical pacing to treat tachyarrythmias is reviewed. The pathogenesis of arrythmia formation, methods of pacing, response of specific tachyarrhythmias to pacing and the clinical application of pacing to terminate and suppress tachyarrhythmias are delineated.
BACKGROUND: Cardiac arrhythmias as a late complication following congenital heart surgery are encountered more and more frequently in clinical practice. The use of new electrophysiological methods of visualisation and mapping improves the efficacy of radio-frequency (RF) ablation of these arrhythmias. AIM: To assess patterns of atrial arrhythmias following congenital heart surgery and to examine the efficacy of RF ablation using the electro-anatomical CARTO system. METHODS: Electrophysiological diagnostic study and RF ablation were performed in 24 consecutive patients (mean age 36+/-18 years) who had atrial arrhythmias following congenital heart surgery. The mechanism of arrhythmia (ectopic or reentrant) and strategy of RF ablation procedure were based on the results of the right atrial map performed during index arrhythmia. RESULTS: The patients were divided into five groups according to the type of congenital heart surgery. The ASD group consisted of 17 patients who had undergone in the past surgery due to atrial septal defect, four patients had a history of surgery due to ventricular septal defect (VSD group), and one patient each had undergone surgery due to corrected transposition of the great arteries (ccTGA), tetralogy of Fallot (TF) or dual-outflow right ventricle (DORV). During diagnostic electrophysiological study typical atrial flutter (AFL) was diagnosed in nine patients from the ASD group, atypical AFL in three ASD patients, and ectopic atrial tachycardia (EAT) in six ASD patients. In one patient EAT was induced after ablation of typical AFL. Of the VSD patients, three had atypical AFL, and one had typical AFL. The patient following surgery for ccTGA had atypical AFL and EAT, whereas in the two remaining patients (DORV and TF) atypical AFL was demonstrated. The efficacy of the first session of RF ablation was 83% and no complications were observed. The efficacy of RF ablation of typical AFL was 90%, atypical AFL 78%, and EAT 86% (NS). During the long-term follow-up (24+/-17 months) arrhythmia recurrences were noted in 2 (10%) out of 20 patients who were effectively treated during the first RF ablation session. CONCLUSIONS: Reentry is the most common electrophysiological mechanism of incisional tachycardias, followed by ectopic atrial tachycardia. RF ablation using the electro-anatomical CARTO system is effective and safe in this group of patients.
On the base of his own studies, the author established that the effective quantity of electric energy for cardioversion is from 150 to 350 W/s. A greater quantity of energy (285.6 +/- 53.8 W/s) is necessary in patients with idiopathic cardiomyopathy than in patients with heart defects, ischemic heart disease and idiopathic rhythm disorder (273.72 +/- 49.1 W/s). In patients with mitral stenosis and prostheses, the quantity used is greater as compared with that in valvulotomized patients and those with mitral-aortic defect. In ventricular tachycardia the mean quantity of electric energy used for the restoration of sinus rhythm proved to be the smallest (182.9 +/- 37.5 W/s), followed by auricular fibrillation (229.5 +/- 40.7 W/s), paroxysmal supraventricular tachycardia (246.3 +/- 57.8 W/s) and auricular flutter--the most (278.8 +/- 51.7 W/s). A correlation has been established between height, body mass, chest measurement and the quantity of electric energy used. It has been proved that when the body mass is smaller then the difference between height and chest measurement, less quantity of energy is necessary for cardioversion, and when it is greater than that difference--the quantity of energy used is greater. The premedication with quinidine does not reduce the quantity of electric energy used.
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Rupture of a Sinus of Valsalva aneurysm into the pulmonary infundibulum with ventricular septal defect was diagnosed by M mode echocardiography The differential diagnosis was prolapse of an aortic valve cusp associated with ventricular septal defect. The relevant features were the presence of an echo anterior to the anterior aortic wall. This echo was related to the aortic valve as a small posterior movement was recorded at aortic valve closure. Systolic fluttering of the pulmonary valve suggested a degree of subvalvular obstruction. Diastolic fluttering was related to the aortic regurgitation immediately below the pulmonary valve. This case confirms the hypothesis that the anterior echo produced by the aortic valve is in fact the left anterior coronary cusp.
Today, the majority of paroxysmal tachycardias can be cured by radiofrequency catheter ablation, obviating the need to use anti-arrhythmia drugs or open heart surgery. The history, the indications, the results and complications of current practice are reviewed.
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Two cases of pre-excitation syndrome are reported and the anaesthesiological management adopted is discussed. After a brief overview of the pathophysiology of the syndrome relative indications and contraindications of the main anaesthetic drugs and volatile agents are analyzed. The high incidence of perioperative atrial fibrillation, atrial flutter or supraventricular tachycardia and the importance of maintaining sinus rhythm is recalled. The task confronting the anaesthetist is to ensure an adequate level of anaesthesia during induction and maintenance while carefully selecting specific drugs associated with minor cardiovascular side effects. In the Authors' experience benzodiazepines, fentanyl, vecuronium and isoflurane have proved to be the most adequate choice for this type of patient.