ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYTwelve patients with medically refractory ventricular tachycardia secondary to ischemic heart disease underwent surgery for cure of their arrhythmia. Preoperatively, the tachycardia could be reproducibly initiated and terminated in each patient by programmed stimulation. In all instances, intraoperative mapping localized the tachycardia to the border of the aneurysm, a site not routinely resected during aneurysmectomy. In nine instances, the area of origin involved the septum. During bypass the tachycardia could still be induced after standard aneurysmectomy or ventriculotomy in 11 of 12 patients. On the basis of intraoperative mapping, resection of endocardium in the area of origin (25–40% the circumference of the aneurysmectomy) up to normal muscle was performed. In one patient without a discrete aneurysm, endocardial excision alone through a ventriculotomy was performed. There was one operative death due to cardiogenic shock (preoperative ejection fraction 5%) and one late death due to rupture of a mycotic aneurysm in the pulmonary artery. Before discharge, all patients underwent a repeat electrophysiologic study off antiarrhythmic agents and in none could ventricular tachycardia be initiated. Hemodynamic and angiographic catheterization showed improved hemodynamics and ejection fractions in all. The 10 survivors remained free of sustained ventricular tachycardia for 9–20 months, with one late nonarrhythmic death.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYThe role of simultaneous and sequential atrioventricular (AV) stimulation in prevention of tachyeardia induction, and the underlying electrophysiologic mechanisms involved, were studied in 10 patients with documented paroxysmal reentrant supraventricular tachycardia (PSVT). Reentry circuit was localized to the AV node in seven of 10. The remaining three cases had Wolff-Parkinson-White (WPW) syndrome and the reentrant circuit retrogradely incorporated an accessory pathway. Progressively earlier atrial premature beats (A2) were introduced while the basic cycle length (BCL) consisted of either atrial pacing alone or simultaneous A and V pacing. Compared with atrial pacing alone, simultaneous A and V pacing during the basic drive completely abolished the PSVT zone in two of seven with AV nodal reentrant PSVT, narrowed the zone in four of seven and facilitated PSVT induction in the other patient. In all patients with AV nodal reentry, significant shortening of AV nodal refractoriness caused by simultaneous antegrade and retrograde AV nodal excitation was responsible for the results. In the three patients with ventricular preexcitation, simultaneous A and V pacing abolished or shortened the PSVT zone in the two cases with type B WPW, but had no effect in the other case (with type A WPW). Introduction of programmed ventricular premature complexes after A2capable of initiating PSVT (sequential AV premature stimulation) prevented PSVT induction by prematurely interrupting the reentry pathway in all instances. Sequential AV premature stimulation was more effective in preventing PSVT when the BCL consisted of simultaneous A and V pacing than was atrial pacing alone. We conclude that simultaneous or sequential AV pacing can either abolish or significantly narrow the PSVT zone, although paradoxical facilitation of reentrant process can occur.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYTwenty-one of 496 (4%) patients with chronic bifascicular block, studied and followed prospectively, had block distal to the His bundle (BDH) induced by atrial pacing during initial electrophysiologic studies. In six, BDH was noted during pacing-induced atrioventricular (AV) nodal Wenckebach periods (at paced rates of 150–190 beats/min), with BDH in the short HH cycles after the AV nodal blocked P (long cycle). The AH interval was normal in all six patients and HV was normal in four. None of the six patients has developed AV block during a mean follow-up of 5.33 ± 0.48 years.In 15 patients, pacing-induced BDH was noted during intact AV nodal conduction (paced rate of 80–200 beats/min). The AH interval was prolonged in one, and HV was prolonged in 10 of the 15 patients. During a mean follow-up of 3.4 ± 0.59 years, seven of these patients developed AV block, one had treadmill-provoked AV block, and two died suddenly (major morbid event in 10 of 15 patients).In conclusion, BDH induced by atrial pacing is an infrequent finding in patients with bifascicular block, and can be a functional as well as a pathologic response. The latter is associated with a high risk of major morbid events (AV block and sudden death).

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYIn 67 consecutive patients with reciprocating tachycardia using an anomalous atrioventricular (AV) or nodoventricular (NV) bypass tract, electrophysiologic findings suggested the coexistence of dual AV nodal pathway conduction in eight patients. The evidence of coexistent dual AV nodal pathways and anomalous bypass tracts took three forms. In four patients, alternating short and long AV nodal conduction time (AH intervals), presumably caused by rate-dependent 2: 1 conduction in the fast AV nodal pathway, were recorded during AV reciprocating tachycardia. Intravenous administration of atropine invariably resulted in 1:1 fast AV nodal pathway conduction during tachycardia in all patients. In three other patients who had anomalous AV bypass tracts capable of only retrograde conduction, discontinuous AV nodal conduction curves (A,A2, H,H2) were generated during atrial extrastimulation. The remaining patient had an anomalous NV bypass tract bridging the slow AV nodal pathway and the right ventricle. During atrial extrastimulation, antegrade block in the fast AV nodal pathway caused antegrade conduction across a pathway composed of the slow AV nodal pathway and the NV bypass tract. This suddenly produced right ventricular preexcitation with inscription of the His bundle deflection within the QRS complex, disrupting the AV nodal conduction curves (A,A, H,H2). A sustained reciprocating tachycardia with a complete left bundle branch block pattern was subsequently initiated using the slow AV node-NV bypass tract pathway for antegrade conduction and the fast AV node-His-Purkinje systenm pathway for retrograde conduction. These observations suggest that dual AV nodal pathway conduction can be identified electrophysiologically in patients with reciprbcating tachycardia involving anomalous bypass tracts, but its manifestations may take several forms.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYPatterns of ventriculoatrial conduction have been used to distinguish retrograde conduction over an accessory atrioventricular pathway from that over the normal atrioventricular conduction system. Ventriculoatrial conduction at a constant interval during incremental ventricular pacing and during progressive prematurity of ventricular extrastimuli has been considered characteristic of conduction over an accessory pathway. We describe three patients with the Wolff-Parkinson-White syndrome who had progressive or sudden increments in ventriculoatrial conduction over an accessory pathway during fixed-rate ventricular pacing or during introduction of ventricular extrastimuli. Such properties have been considered characteristic of conduction over the normal atrioventricular conduction system. We conclude that retrograde conduction over accessory pathways may resemble conduction over the normal atrioventricular conduction system.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYIntracardiac electrophysiologic studies were performed on 28 infants and children, ages 1 month to 18 years, with the Wolff-Parkinson-White syndrome to try to determine 1) the electrophysiologic characteristics of the accessory connection and 2) the mechanisms of associated supraventricular dysrhythmias. Although the antegrade refractory periods of the normal conduction system were shorter than those found in adults, those of the accessory connection were slightly longer.Reciprocating supraventricular tachycardia (SVT), which had been a clinical problem in 26 of 28, could be induced in the laboratory in all 26 subjects. The mechanism involved reentry with antegrade conduction through the atrioventricular (AV) node and retrograde through the accessory connection in 22. Eleven of these 22 had a wide QRS during tachycardia due to a bundle branch block. Three other subjects had wide QRS tachycardia, but the mechanism involved antegrade conduction through the accessory connection and retrograde through the AV node. The other patient had AV node reentry tachycardia. Two patients did not have clinical SVT, and in these two, SVT could not be induced. Neither patient had retrograde conduction through the accessory connection.The site of the accessory connection could be identified in 26 subjects by the sequence of retrograde activation of the atrium during SVT or ventricular pacing. Digitalis shortened the refractory period of the accessory connection in five of the eight patients studied.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYSubxiphoid, two-dimensional echocardiograms (S2DE) were performed and interpreted before diagnostic cardiac catheterization on 59 neonates who weighed 1.3–6.0 kg (median 3.3 kg) and were 1–35 days old (median 4.5 days). The echocardiographic studies were successfully performed on 58 of 59 infants. Using appropriate longitudinal and transverse projections, S2DE permitted simultaneous visualization of the branch pulmonary arteries, proximal thoracic aorta and ventriculoarterial attachments. D-transposition of the great arteries was correctly predicted in all 16 infants with levocardia, situs solitus and atrioventricular concordance. In these patients, the standard left ventricular longitudinal projection demonstrated the bifurcating main pulmonary artery attached to the posterior ventricle; the transverse projection displayed the relationship of the proximal thoracic aorta to the anterior ventricle. The broad acoustical window using the subxiphoid approach in conjunction with a high-frequency focused transducer and a large active-element diameter permitted detailed imaging of intra- and supracardiac structures.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

SUMMARYTo determine whether cold could activate the kallikrein-kinin system in vivo as it does in vitro, the circulating systemic concentrations of bradykinin were serially measured in 10 children with congenital diseases of the heart undergoing corrective cardiac surgery. Bradykinin was measured by radioimmunoassay in blood samples obtained before, during and after profound hypothermia (to 18°C) and cardiopulmonary bypass. The circulating concentrations of bradykinin increased significantly as body temperature decreased during surface cooling. The increase in circulating bradykinin was associated with a decrease in the circulating level of bradykininogen, the precursor of bradykinin. With the onset of cardiopulmonary bypass and hence, removal of the lung and pulmonary converting enzyme from the circulation, there was a further rise in the already elevated concentrations of bradykinin. This is the first in vivo demonstration that hypothermia leads to an increase in the circulating concentrations of bradykinin.

ISSN:0009-7322    

出版商:OVID    

年代:1979

数据来源: OVID