1/7. Intermittent bundle-branch block in patients with accessory atrio-His or atrio-AV nodal pathways. Variants of the lown-ganong-levine syndrome.Intracardiac electrophysiological studies were performed in two patients with a documented history of repetitive supraventricular tachyarrhythmias. Case 1, with short PR interval and narrow QRS complexes had a short AH interval and intermittent right bundle-branch block. Thus the short PR wide QRS syndrome is not always a result of the wolff-parkinson-white syndrome but can also be seen in the lown-ganong-levine syndrome coexisting with bundle-branch block. Case 2, with normal PR and AH at the lower limits of normal, showed the dual pathway response to atrial pacing that can occur in patients with lown-ganong-levine syndrome. He also had tachycardia-dependent right bundle-branch block and left posterior hemiblock. Therefore, neither the short PR interval nor the narrow QRS complexes characterized these forms of pre-excitation. The constant features were, from the clinical viewpoint, the occurrence of repetitive supraventricular tachyarrhythmias, and electrophysiologically the abnormal response to atrial stimulation.- - - - - - - - - - ranking = 1keywords = pre-excitation (Clic here for more details about this article) |
2/7. Sequential biventricular resynchronization optimized by myocardial strain rate analysis: a case report.We report the case of a patient with severe left ventricular systolic dysfunction and left bundle branch block in whom cardiac resynchronization therapy (CRT) was optimized by tissue Doppler imaging. A horizontal mechanical asynchrony index was derived from tissue Doppler regional longitudinal strain rate profiles as the time difference at the onset of shortening between septum, lateral, anterior and inferior walls. The interventricular delay was modulated in order to achieve the smallest asynchrony index; on the basis of this parameter a sequential (S)-CRT with a left ventricular pre-excitation of 20 ms was definitively programmed. This optimized S-CRT was followed by an acute improvement in systolic cardiac performance and by a long-term (12 months) clinical benefit as well as by a documented decrease in LV chamber size due to a true reverse remodeling effect. Thus, in some patients S-CRT may be more effective than conventional CRT. Tissue Doppler-derived strain rate analysis can provide information on the degree of left intraventricular asynchrony allowing the modulation of a tailored interventricular delay.- - - - - - - - - - ranking = 1keywords = pre-excitation (Clic here for more details about this article) |
3/7. "Nodoventricular" accessory pathway: evidence for a distinct accessory atrioventricular pathway with atrioventricular node-like properties.Two patients are described with recurrent pre-excited tachycardia and electrophysiologic characteristics typically ascribed to a nodoventricular accessory connection. The accessory pathway in each case demonstrated rate-dependent prolongation of conduction time and a low right ventricular insertion site; it was associated with a left bundle branch block configuration during pre-excitation. Intraoperatively, the pathway was demonstrated to originate at the anterior right atrioventricular (AV) anulus and not at the AV node. These data suggest that a "typical" nodoventricular pathway, by electrophysiologic criteria, may in fact be an AV pathway with AV node-like conduction properties and a distal right ventricular insertion site.- - - - - - - - - - ranking = 1keywords = pre-excitation (Clic here for more details about this article) |
4/7. atrioventricular block complicating amiodarone-induced hypothyroidism in a patient with pre-excitation and rate-dependent bilateral bundle branch block.As a clinical entity atrioventricular (AV) block due to hypothyroidism is rare. Such a case induced by hypothyroidism complicating long-term therapy with amiodarone in a 45 year old woman with pre-excitation is presented. Electrophysiologic data obtained before and during thyroxine replacement therapy showed that hypothyroidism lengthens the effective refractory period of the atria, AV node, bypass tract and His-Purkinje system (that in the ventricle not being measured); this lengthening resembles the effects of long-term administration of amiodarone. These observations suggest that depressed thyroid function may be protective against arrhythmias but a patient with preexisting conduction system disease may develop AV block. The tendency to develop AV block in a patient who is euthyroid was reduced by bypass tract conduction. These findings are significant not only in monitoring amiodarone effects during chronic prophylactic drug therapy but also in providing further insight into the complex interrelation between the action of the drug and the thyroid hormones on cardiac muscle.- - - - - - - - - - ranking = 5keywords = pre-excitation (Clic here for more details about this article) |
5/7. association of an accessory atrioventricular pathway and ipsilateral bundle branch block.We performed electrophysiological study and radionuclide phase imaging in a patient with intermittent wolff-parkinson-white syndrome type A and left bundle branch block. The presence of a left-sided accessory pathway was proven by eccentric retrograde atrial activation. Phase-imaging revealed delayed left ventricular phase angles when left bundle branch block was present in the electrocardiogram. There was an advance of early phase angles at the ventricular insertion of the accessory pathway as well as delayed phase angles in the rest of the left ventricle when the pre-excitation pattern was seen electrocardiographically.- - - - - - - - - - ranking = 1keywords = pre-excitation (Clic here for more details about this article) |
6/7. Paroxysmal ventricular tachycardia in wolff-parkinson-white syndrome: case report and review of the literature.A case with Type A Wolff-Parkinson-White pattern and recurrent sustained ventricular tachycardia is presented. Because of ventricular pre-excitation, electrocardiographic clues suggestive of ventricular tachycardia were ignored and the diagnosis of supraventricular tachycardia with conduction to the ventricles over the accessory pathway was made during each admission to the hospital. Ventricular tachycardia was suspected only when programmed stimulation studies performed twelve years after initial presentation and many hospitalizations failed to induce a tachycardia with a QRS pattern similar to that of spontaneously occurring tachycardia. The diagnosis of ventricular tachycardia was later confirmed by intracardiac recordings made during a spontaneous episode of tachycardia. tachycardia was unresponsive to all conventional antiarrhythmic agents but was controlled with amiodarone. The differential diagnosis of wide QRS complex tachycardia in patients with wolff-parkinson-white syndrome, the implications of correctly diagnosing the tachycardia, and the usefulness of intracardiac electrophysiologic studies in differentiating supraventricular tachycardia with aberrant conduction from ventricular tachycardia are discussed.- - - - - - - - - - ranking = 1keywords = pre-excitation (Clic here for more details about this article) |
7/7. Pre-excitation of the ventricle associated with total intra His bundle block.A case with total intra-His bundle block and intermittent pre-excitation syndrome is presented. During A-V conduction there was a P-delta interval of 130 msec. with a P-A interval of 20 msec., an A-H interval of 60 msec. and an H-V interval of 50 msec. During rapid atrial pacing the P-delta interval increased primarily due to an A-H1 prolongation and a Mobitz type 2 block and total A-V block occured at increasing rates showing H1 following every A spike. The escape beats showed a normal width of the QRS complexes with preceding H2 spikes. After administration of ajmaline the bypass tract was blocked and constant total A-V block occurred. It was concluded that there was a constant total intra-His bundle block and a nodoventricular or fasciculoventricular bypass tract with prolonged conduction to the ventricle. This bypass tract blocked sometimes spontaneously and could also be blocked by rapid atrial pacing and administration of drugs. The close anatomic proximity of the His bundle and Mahaim fibers is responsible for the simultaneous block resulting in total atrioventricular block.- - - - - - - - - - ranking = 1keywords = pre-excitation (Clic here for more details about this article) |