RESUMEN
Three cases of twiddler's syndrome in patients with an abdominally implanted cardioverter defibrillator (ICD) and an endocardial lead system are reported. The condition was detected when an increase in pacing threshold or lead impedance was noted at routine follow-up. Successful revision was possible in all patients; however, a recurrence in one patient necessitated removal of the device. Elderly female patients with some degree of obesity appear most susceptible. Minimizing pocket size and suturing of the device to the fascia should decrease the chance of developing this problem.
Asunto(s)
Desfibriladores Implantables/efectos adversos , Migración de Cuerpo Extraño/diagnóstico , Anciano , Falla de Equipo , Femenino , Migración de Cuerpo Extraño/diagnóstico por imagen , Migración de Cuerpo Extraño/cirugía , Humanos , Masculino , Radiografía , Recurrencia , Reoperación , Rotación , SíndromeRESUMEN
Junctional rhythm is commonly observed during radiofrequency catheter ablation of the fast or slow pathways of atrioventricular nodal reentrant tachycardia (AVNRT). However, the origin of these beats remains unclear. We analyzed the retrograde atrial activation sequence of 16 patients (mean +/- SD: 41.2 +/- 18.9 years old) undergoing catheter ablation for typical AVNRT with detailed catheter mapping of the triangle of Koch. The earliest atrial activations were concordant during tachycardia and junctional rhythm in only 5 of 16 patients. The findings suggest that junctional rhythm is unlikely to represent direct stimulation of the atrioventricular (AV) node via a discrete slow pathway but rather results from enhanced automaticity from > or =1 sites in the AV nodal transitional zone. The ensuing atrial activation pattern results from anisotropic spread from these sites. In addition, these data imply that the original concept of the AV node comprising 2 anatomically defined pathways may not be valid, and that a functionally defined pathway model may be a more accurate representation.
Asunto(s)
Ablación por Catéter , Sistema de Conducción Cardíaco/fisiopatología , Taquicardia por Reentrada en el Nodo Atrioventricular/cirugía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Electrocardiografía , Femenino , Atrios Cardíacos/inervación , Humanos , Masculino , Persona de Mediana Edad , Taquicardia por Reentrada en el Nodo Atrioventricular/fisiopatologíaRESUMEN
A retrospective study of 729 consecutive patient-activated continuous loop recorders shows that these devices provide useful diagnostic information about the presence or absence of transient arrhythmias in carefully selected patients with certain specific complaints.
Asunto(s)
Arritmias Cardíacas/diagnóstico , Electrocardiografía Ambulatoria/instrumentación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Diseño de Equipo , Medicina Familiar y Comunitaria , Femenino , Humanos , Masculino , Persona de Mediana Edad , Síncope/diagnósticoRESUMEN
BACKGROUND: Atrial dysrhythmia patients have exaggerated intra-atrial conduction delays and prolonged relative refractoriness in response to atrial premature depolarizations (APDs). Furthermore, atrial fibrillation (AF) is more readily inducible by APDs from the high right atrium (HRA) than the coronary sinus (CS). In this study, we postulated that site-specific intra-atrial conduction delays can explain why AF is initiated more from the HRA than from the CS. METHODS AND RESULTS: We examined 17 patients (age, 49 +/- 22 years) without a history of atrial flutter, AF, or structural heart disease. Programmed stimulation was carried out from the HRA and distal CS, and bipolar recordings were made at the HRA, His bundle, posterior triangle of Koch, and CS. More prolongations in conduction and relative refractoriness in all intra-atrial sites were observed during HRA than CS APDs. AF was induced in 8 patients after HRA and not CS stimulation. During HRA stimulation, patients with AF inducibility exhibited significant prolongation of conduction to the posterior triangle of Koch and marked broadening of the posterior triangle of Koch electrogram compared with CS stimulation. In patients without AF inducibility, the posterior triangle of Koch electrogram width was the same during HRA and CS stimulation. CONCLUSIONS: The existence of site-dependent intra-atrial conduction delays and site-dependent dispersion of refractoriness appears to be a common property of the atrial myocardium and does not necessarily forecast AF inducibility. However, the presence of nonuniform anisotropic characteristics of the posterior triangle of Koch may be critical for AF induction.
Asunto(s)
Fibrilación Atrial/fisiopatología , Aleteo Atrial/fisiopatología , Función Atrial , Sistema de Conducción Cardíaco/fisiopatología , Cardiopatías/fisiopatología , Adulto , Anciano , Anisotropía , Función del Atrio Derecho , Vasos Coronarios/fisiopatología , Estimulación Eléctrica , Femenino , Humanos , Masculino , Persona de Mediana Edad , Periodo Refractario ElectrofisiológicoRESUMEN
BACKGROUND: Selective ablation of either the fast of the slow pathway resulting in cure of AV nodal reentry tachycardia (AVNRT) has led to the concept that these pathways are discrete, anatomically defined structures. We hypothesized that if a discrete retrograde fast pathway exists, it should be possible to record a single focus of early atrial activation near the apex of Koch's triangle, with sequential spread of depolarization to the rest of the atria. METHODS AND RESULTS: We evaluated 46 patients (33 women, 13 men; mean age, 45 +/- 17 years) undergoing electrophysiology study and catheter ablation for typical AVNRT. Retrograde atrial activation during AVNRT (337 +/- 43 ms) and ventricular pacing at a similar cycle length (352 +/- 51 ms) was recorded in the region of Koch's triangle with a decapolar catheter in the His bundle position, a multipolar catheter in the coronary sinus, and a deflectable quadripolar catheter along the tricuspid annulus anterior to the coronary sinus ostium. Earliest atrial activation was recorded at the apex of the triangle of Koch in 38 patients during ventricular pacing and in 43 patients during AVNRT. A broad wave front of atrial activation was recorded in 17 patients during ventricular pacing and in 26 patients during AVNRT. During AVNRT, only 2 patients had a single early site with focal and sequential activation along the tendon of Todaro. There was concordance in the pattern of atrial activation between ventricular pacing and AVNRT in only 21 of 46 patients. CONCLUSIONS: Retrograde atrial activation over the fast pathway is heterogeneous within Koch's triangle and the coronary sinus, both for the entire population and for individual patients during different modes of activation. These data do not support the concept of an anatomically discrete retrograde fast pathway.
Asunto(s)
Sistema de Conducción Cardíaco/fisiopatología , Taquicardia por Reentrada en el Nodo Sinoatrial/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Cateterismo Cardíaco , Estimulación Cardíaca Artificial , Ablación por Catéter , Femenino , Sistema de Conducción Cardíaco/cirugía , Humanos , Masculino , Persona de Mediana Edad , Taquicardia por Reentrada en el Nodo Sinoatrial/cirugíaRESUMEN
This study was conducted to systematically characterize the excitable gap and conduction properties of the reentrant circuit during atrioventricular nodal reentrant tachycardia (AVNRT). Previous studies have attempted to analyze these properties by introducing single ventricular extrastimuli during tachycardia. These studies have been limited, however, by the inability of single extrastimuli to engage the circuit in the majority of patients studied. Thus, in most cases, the nature of the excitable gap and the conduction properties of the anterograde and retrograde limbs of the circuit during tachycardia remain undefined. In this series, 11 patients with typical AVNRT were studied. During tachycardia, both single and double ventricular extrastimuli (the first extrastimulus acting as a conditioning stimulus) were used to scan diastole. The resetting response of the reentrant circuit, as well as the conduction properties of the retrograde fast and anterograde slow pathways, was recorded and analyzed. Whereas atrial preexcitation and resetting of the reentrant circuit could be demonstrated in only 1 patient with single ventricular extrastimuli, resetting was achieved in all 11 patients with closely coupled double ventricular extrastimuli. Over the full range of coupling intervals used, no retrograde delay in fast pathway conduction could be demonstrated before tachycardia termination or ventricular refractoriness. Penetration of the reentrant circuit resulted in a progressive increasing delay in the anterograde portion of the subsequent return cycle and an increasing resetting response pattern in all cases. Thus, the reentrant circuit during AVNRT demonstrates heterogeneous excitability. While the fast pathway remains fully excitable during tachycardia, the slow pathway uniformly demonstrates decremental conduction, resulting in an increasing resetting response pattern.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Sistema de Conducción Cardíaco/fisiopatología , Taquicardia por Reentrada en el Nodo Atrioventricular/fisiopatología , Adulto , Estimulación Cardíaca Artificial/métodos , Electrocardiografía/métodos , Femenino , Atrios Cardíacos/fisiopatología , Ventrículos Cardíacos/fisiopatología , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Constrictive pericarditis is a complex disorder characterized by abnormal thickening of the pericardium that leads to pathologic changes in cardiac hemodynamic data. The disorder can be suspected by history and physical findings. Data from echocardiography, CT, and MRI offer diagnostic information. The diagnosis cannot generally be established with certainty by noninvasive methods. Additional information from cardiac catheterization may help confirm the diagnosis. Together, these diagnostic modalities aid in the assessment of disease and help to differentiate it from related conditions such as restriction, cardiac tamponade, and right ventricular infarction. Treatment is largely surgical, and new techniques and approaches have made it relatively safe. Early diagnosis and pericardiectomy may lead to cure in most patients.
Asunto(s)
Pericarditis Constrictiva , Cateterismo Cardíaco , Humanos , Pericarditis Constrictiva/diagnóstico , Pericarditis Constrictiva/etiología , Pericarditis Constrictiva/fisiopatologíaRESUMEN
We studied the vasomotion of epicardial coronary arteries during exercise and tested the hypotheses that abnormal vasoconstriction is related to the presence of atherosclerosis and may be related to endothelial dilator dysfunction. During cardiac catheterization quantitative coronary angiography was performed in 21 patients during supine bicycle exercise. 21 of 28 smooth, angiographically normal vessel segments dilated (14.0 +/- 1.8%) during exercise; four smooth segments did not change whereas only three constricted. In contrast, 15 of 16 vessel segments with irregularities constricted in response to exercise (17.0 +/- 0.1%) with only one segment dilating. All 10 stenotic segments constricted to exercise (23 +/- 4%). Six patients also received intracoronary acetylcholine before exercise to test endothelium-dependent dilator function. In five of six patients all nine vessel segments showed the same directional response to acetylcholine and exercise. Three irregular and two stenotic segments constricted with acetylcholine (51 +/- 21%) and exercise (9.0 +/- 0.6%). In contrast, four smooth segments dilated to acetylcholine (19 +/- 6%) and exercise (9 +/- 1%). Both exercise and acetylcholine generally dilated smooth but constricted irregular and stenosed coronary segments. It appears likely that atherosclerosis plays an important role in the abnormal vasomotion of diseased coronary arteries during exercise and the pattern of abnormality suggests impairment of vasodilator function.