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1.
J Interv Card Electrophysiol ; 5(3): 267-73, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11500581

RESUMEN

Emerging evidence suggests that atrial fibrillation is not a benign arrhythmia. It is associated with increased risk of death. The magnitude of association is controversial and potential causes remain unknown. Patients in the registry of the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial form the basis for this report. Baseline variables, in particular the presence or absence of a history of atrial fibrillation/flutter, were examined in relation to survival. Multivariate Cox regression was used to adjust for differences in important baseline co-variables using 27 pre-selected variables. There were 3762 subjects who were followed for an average of 773+/-420 days; 1459 (39 %) qualified with ventricular fibrillation and 2303 (61 %) with ventricular tachycardia. A history of atrial fibrillation/flutter was present in 24.4 percent. There were many differences in baseline variables between those with and those without a history of atrial fibrillation/flutter. After adjustment for baseline differences, a history of atrial fibrillation/flutter remained a significant independent predictor of mortality, (relative risk=1.20; 95 % confidence intervals=1.03-1.40; p=0.020). Antiarrhythmic drug use, other than amiodarone or sotalol, was also a significant independent predictor of mortality (relative risk 1.34; 95 % confidence intervals 1.07-1.69, p=0.011. Atrial fibrillation/flutter is a significant independent risk factor for increased mortality in patients presenting with ventricular tachyarrhythmias. This risk may have been overestimated in previous studies that could not adjust for the proarrhythmic effects of antiarrhythmic drugs other than amiodarone or sotalol.


Asunto(s)
Antiarrítmicos/uso terapéutico , Fibrilación Atrial/mortalidad , Fibrilación Atrial/terapia , Desfibriladores Implantables , Taquicardia Ventricular/mortalidad , Taquicardia Ventricular/terapia , Anciano , Fibrilación Atrial/diagnóstico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Probabilidad , Modelos de Riesgos Proporcionales , Ensayos Clínicos Controlados Aleatorios como Asunto , Valores de Referencia , Sistema de Registros , Análisis de Regresión , Medición de Riesgo , Factores de Riesgo , Sensibilidad y Especificidad , Índice de Severidad de la Enfermedad , Análisis de Supervivencia , Taquicardia Ventricular/diagnóstico , Resultado del Tratamiento
2.
J Cardiovasc Electrophysiol ; 10(7): 973-80, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10413377

RESUMEN

INTRODUCTION: New defibrillation techniques are often compared to standard approaches using the defibrillation threshold. However, inference from thresholding data necessitates extrapolation from reactions to relatively ineffective shocks, an error prone procedure requiring large sample sizes for hypothesis testing and large safety margins for defibrillator implantation. In contrast, this article presents a clinically validated statistical model of a minimum error, four-shock defibrillation testing protocol for estimating the 80% effective defibrillation strength for a given patient (ED80). METHODS AND RESULTS: A Bayesian statistical model was constructed assuming that the defibrillation dose-response curve is sigmoidal, and the ED80 is between 150 and 750 V. The model was used to design a minimum predicted error testing protocol and estimates. To prospectively validate the testing protocol and estimates, 170 patients received voltage-programmed biphasic testing. Four fibrillation episodes were induced and terminated in each patient according to the Bayesian up-down protocol. In addition, a validation attempt was made at the estimated ED80 rounded up to the nearest 50 V. In order to estimate the safety margin, in 136 patients, a defibrillation attempt was made at the rounded ED80 + 100 V. Of the 170 attempts at the rounded ED80, 143 (84%) attempts terminated fibrillation. Of the 136 attempts at the rounded ED80 + 100 V, 133 (98%) were effective. CONCLUSIONS: The four-shock Bayesian up-down protocol is the first clinical protocol to accurately predict an ED80 voltage. A 100 V increment above the ED80 provides an adequate safety margin. This simple and accurate method for estimating a highly effective defibrillation dose may be a valuable tool for population-based clinical hypothesis testing, as well as defibrillator implantation.


Asunto(s)
Desfibriladores Implantables/normas , Cardioversión Eléctrica , Modelos Teóricos , Fibrilación Ventricular/terapia , Adulto , Anciano , Anciano de 80 o más Años , Teorema de Bayes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos , Resultado del Tratamiento
3.
Circulation ; 99(14): 1843-50, 1999 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-10199881

RESUMEN

BACKGROUND: Cardiologists often use clinical variables to determine the need for electrophysiological studies to stratify patients for risk of sudden death. It is not clear whether this is rational in patients with coronary artery disease, left ventricular dysfunction, and nonsustained ventricular tachycardia. METHODS AND RESULTS: We analyzed the first 1721 patients enrolled in the Multicenter UnSustained Tachycardia Trial to determine whether clinical variables could predict which patients would have inducible sustained monomorphic ventricular tachycardia. The rate of inducibility of sustained ventricular tachycardia was significantly higher in patients with a history of myocardial infarction and in men compared with women. There was a progressively increased rate of inducibility with increasing numbers of diseased coronary arteries. There was a significantly lower rate of inducibility in patients with prior coronary artery bypass surgery and in patients who also had noncoronary cardiac disease. The rate of inducibility was higher in patients of white race, patients with recent (

Asunto(s)
Estimulación Cardíaca Artificial , Enfermedad Coronaria/fisiopatología , Taquicardia Ventricular/etiología , Anciano , Enfermedad Coronaria/complicaciones , Enfermedad Coronaria/diagnóstico , Electrodiagnóstico , Femenino , Predicción , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/complicaciones , Caracteres Sexuales , Taquicardia Ventricular/fisiopatología
4.
Pacing Clin Electrophysiol ; 19(9): 1351-4, 1996 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-8880799

RESUMEN

RF catheter ablation of accessory bypass tracts associated with the Wolff-Parkinson-White syndrome has become an accepted and widespread therapy. When bypass tracts are located in the free wall of the left ventricle, a single catheter technique may be utilized. A single catheter is placed via the femoral artery, across the aortic valve into the left ventricle. Mapping is performed during sinus rhythm, and ablation performed at the site of recording of Kent bundle activation. We describe a case of a patient with Wolff-Parkinson-White syndrome presenting with rapid atrial fibrillation requiring cardioversion. This patient subsequently underwent catheter ablation of a left free-wall bypass tract using the single catheter technique. At baseline, preexcitation and right bundle branch block (RBBB) were present on the ECG. During catheter ablation of the accessory pathway, transient complete AV block was seen. This was felt likely to be due to trauma to the His bundle, or more likely to the left bundle branch, as the ablation catheter crossed the aortic valve. The bypass tract was successfully ablated after placement of a temporary right ventricular pacemaker. AV conduction resumed with a pattern of RBBB. A temporary right ventricular pacing catheter should be placed prior to RF ablation of left-sided bypass tracts when the ECG is also suggestive of RBBB.


Asunto(s)
Bloqueo de Rama/cirugía , Ablación por Catéter/efectos adversos , Bloqueo Cardíaco/etiología , Síndrome de Wolff-Parkinson-White/cirugía , Electrocardiografía , Humanos , Masculino , Persona de Mediana Edad
5.
Pacing Clin Electrophysiol ; 15(12): 2236-9, 1992 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1282243

RESUMEN

Permanent pacemakers may be implanted in operating rooms, special procedure laboratories, or cardiac catheterization laboratories. Previous investigators have shown no difference in efficacy or complications in the operating room versus the cardiac catheterization laboratory. We retrospectively analyzed the hospital bills of 30 patients undergoing permanent pacemaker implantation at our institution. Group I was 15 consecutive patients implanted in the operating room and group II was 15 consecutive patients implanted in the cardiac catheterization laboratory, all by the same operators. Hospital charges that were specific to the site of implantation were analyzed. Physician charges for implantation, anesthesiologist, and radiologist charges were not analyzed. There were no in-hospital complications in either group. The mean charges for group I were $1,856.00 and group II were $1,075.00 (P < 0.001). We conclude that implantation of permanent pacemakers in the cardiac catheterization laboratory is associated with significantly lower hospital charges compared to implantation in the operating room and has an equally low complication rate.


Asunto(s)
Cateterismo Cardíaco/economía , Honorarios Médicos , Laboratorios de Hospital/economía , Quirófanos/economía , Marcapaso Artificial/efectos adversos , Marcapaso Artificial/economía , Anciano , Costos y Análisis de Costo , Femenino , Humanos , Masculino , Estudios Retrospectivos
6.
Pacing Clin Electrophysiol ; 15(9): 1244-7, 1992 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-1383983

RESUMEN

We report the use of a steerable hydrophilic guidewire for permanent pacemaker implantation. This wire, previously used for peripheral vascular and cardiac angiography, is able to be steered and passed in many situations when a standard guidewire cannot be used. We report three cases where the standard J-tipped guidewire could not be passed by either the cephalic or subclavian route and the hydrophilic guidewire allowed for successful atraumatic placement of a sheath and pacemaker lead.


Asunto(s)
Marcapaso Artificial , Adulto , Anciano , Cateterismo/instrumentación , Femenino , Fluoroscopía , Humanos , Masculino , Métodos , Persona de Mediana Edad
7.
Pacing Clin Electrophysiol ; 15(3): 248-51, 1992 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-1372716

RESUMEN

Steroid eluting leads may allow for lower chronic pacing thresholds and therefore lower pacing outputs. Twenty-two patients (15 presenting with syncope) were implanted with VVI or VVIR pacemakers and transvenous steroid eluting leads and followed for a mean of 20.6 months while being paced at 1.6 V and 0.6 msec. Mean acute voltage pacing thresholds were 0.40 V at 0.5 msec and chronic pulse width thresholds were 0.21 msec at 0.8 V. Pacemaker function was documented with one to three 24-hour Holter monitors, attached during the 2-6 week postimplant period, bimonthly transtelephonic monitoring, and monthly pacemaker clinic visits. No patient developed recurrent symptoms and consistent capture was verified in all patients on every 24-hour Holter recording and transtelephonic monitor. Chronic ventricular pacing at an output of 1.6 V at 0.6 msec is safe and effective when using a steroid eluting lead and potentially has implications for pacemaker longevity.


Asunto(s)
Fibrilación Atrial/terapia , Estimulación Cardíaca Artificial/métodos , Marcapaso Artificial , Síndrome del Seno Enfermo/terapia , Síncope/terapia , Adulto , Anciano , Anciano de 80 o más Años , Fibrilación Atrial/epidemiología , Electrodos Implantados , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Seguridad , Síndrome del Seno Enfermo/epidemiología , Síncope/epidemiología , Factores de Tiempo
8.
Am Heart J ; 122(6): 1515-8, 1991 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1957744

RESUMEN

Fifty-four patients presenting with stenotic lesions in a major coronary artery visually estimated by diagnostic angiography to be greater than 90% but less than 100% were randomized to one of two angioplasty regimens, predilatation (group 1) or no predilatation (group 2). In group 1, the artery was initially dilated with a 2 mm balloon followed by a balloon that was considered by the operator to be the definitive size to fully dilate the target vessel. In group 2, the artery was dilated with a balloon deemed the definitive size to complete the angioplasty procedure. There were no statistical differences between groups with respect to age, sex, history of unstable angina, or prior acute myocardial infarction. There were also no significant differences in the angiographic characteristics of the coronary lesions including artery location, lesion length, concentric or eccentric morphology, tubular versus discrete stenosis, calcium in lesions, or lesions on a bend. Following angioplasty, luminal filling defects were present in 5% of the predilated group and in 9% of the nonpredilated group (p = NS). The incidence of luminal border haziness at the dilatation site did not differ between groups, seven (35%) in group 1 versus eight (24%) in group 2. Angiographic evidence of a linear dissection at the angioplasty site was also similar between groups, one (5%) in group 1 versus five (15%) in group 2. Occlusive complications were witnessed in 10% of the predilated group and 12% of the nonpredilated group (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Angioplastia Coronaria con Balón/métodos , Enfermedad Coronaria/terapia , Vasos Coronarios/lesiones , Angioplastia Coronaria con Balón/efectos adversos , Angioplastia Coronaria con Balón/instrumentación , Cineangiografía , Angiografía Coronaria , Enfermedad Coronaria/complicaciones , Enfermedad Coronaria/diagnóstico por imagen , Humanos
9.
J Am Coll Cardiol ; 18(6): 1517-23, 1991 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-1939955

RESUMEN

Chronic occlusion of saphenous vein aortocoronary bypass grafts is a common problem. Although percutaneous transluminal angioplasty of a saphenous vein with a stenotic lesion is feasible, angioplasty alone of a totally occluded vein graft yields uniformly poor results. Patients with such occlusion are often subjected to repeat aortocoronary bypass surgery. Experience with a new technique that allows angioplasty to be performed in a totally occluded saphenous vein bypass graft is reported. This technique utilizes infusion of prolonged low dose urokinase directly into the proximal portion of the occluded graft. Forty-six consecutive patients with 47 totally occluded grafts were studied. Patients had undergone end to side saphenous vein bypass grafting 1 to 13 (mean 7) years previously. All patients presented with new or worsening angina pectoris with ST-T changes or non-Q wave acute myocardial infarction and all had a totally occluded saphenous vein bypass graft. The new technique entailed the positioning of an angiographic catheter into the stub of the occluded graft and the advancement of an infusion wire into the graft. Patients were returned to the coronary care unit, where urokinase was delivered at a dose of 100,000 to 250,000 U/h. The total dose of urokinase ranged from 0.7 to 9.8 million U over 7.5 to 77 h (mean 31). After therapy, recanalization was seen in 37 (79%) of the 47 grafts. In 20 successfully treated patients, angiography was performed 1 to 24 (mean 11) months after treatment; 13 (65%) of these grafts were patent.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Puente de Arteria Coronaria , Enfermedad Coronaria/tratamiento farmacológico , Oclusión de Injerto Vascular/tratamiento farmacológico , Vena Safena/trasplante , Terapia Trombolítica , Activador de Plasminógeno de Tipo Uroquinasa/uso terapéutico , Anciano , Anciano de 80 o más Años , Enfermedad Crónica , Angiografía Coronaria , Enfermedad Coronaria/diagnóstico por imagen , Femenino , Estudios de Seguimiento , Oclusión de Injerto Vascular/diagnóstico por imagen , Humanos , Infusiones Intravenosas/métodos , Masculino , Persona de Mediana Edad , Factores de Tiempo , Resultado del Tratamiento , Activador de Plasminógeno de Tipo Uroquinasa/administración & dosificación , Grado de Desobstrucción Vascular
10.
Circulation ; 82(4): 1289-95, 1990 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-2401063

RESUMEN

Programmed ventricular stimuli introduced during sustained monomorphic ventricular tachycardia frequently reset the tachycardia, resulting in a less than fully compensatory pause. A resetting response curve is generated when the set of return cycles is evaluated as the function of the coupling intervals of the extrastimuli delivered during the ventricular tachycardia. If the stimulated wave front encounters tissue within the tachycardia circuit that is not fully recovered, interval-dependent conduction changes should occur producing an increasing resetting response pattern. We quantified the magnitude of this interval-dependent conduction slowing in 17 morphologically distinct ventricular tachycardias. The slope of the increasing limb of the resetting response curve was determined by linear regression analysis and ranged from -0.30 to -1.14 (mean +/- SD, 0.70 +/- 0.25). Seven of the 17 ventricular tachycardias (41%) terminated during introduction of ventricular extrastimuli. The slope of the resetting response pattern in those ventricular tachycardias that terminated were significantly steeper than in those that did not terminate (-0.85 +/- 0.15 versus -0.61 +/- 0.21, respectively, p = 0.025). Six of the seven ventricular tachycardias terminated with programmed ventricular stimuli had a slope steeper than -0.75, whereas only one of 10 ventricular tachycardias that did not terminate exceeded this value. In conclusion, the slope of the increasing portion of the resetting response curve correlates with ability to terminate uniform sustained ventricular tachycardia by timed extrastimuli. This slope is the quantification of the magnitude of interval-dependent conduction slowing. Additionally, tissue within the reentrant circuit displaying greater degrees of interval-dependent conduction slowing may also have relatively longer effective refractory periods.


Asunto(s)
Taquicardia/fisiopatología , Estimulación Cardíaca Artificial , Sistema de Conducción Cardíaco/fisiopatología , Humanos , Análisis de Regresión
12.
Am J Cardiol ; 63(20): 1455-61, 1989 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-2729132

RESUMEN

To investigate the mechanism of slowing of the rate of ventricular tachycardias (VTs) by procainamide, resetting response patterns were characterized in 24 VTs in 22 patients. All patients had coronary artery disease and inducible sustained VT during procainamide therapy. Only tachycardias with the same surface QRS morphology before and after procainamide were studied: all were slowed by procainamide. The mean cycle length was 292 +/- 61 ms before and 374 +/- 61 ms after procainamide (p less than 0.05). The mean effective refractory period, measured at the right ventricle, was 241 +/- 21 ms before and 261 +/- 24 ms after procainamide (p less than 0.05). During procainamide therapy, single and double extrastimuli were delivered during VT and resetting response patterns identified. Patterns were characterized as flat, increasing or flat plus increasing. Resetting was seen in 17 (71%) of these VTs and resetting response patterns were identified in 16 (94%) of these. The resetting response pattern was flat in 7, flat plus increasing in 5 and increasing in 4. The finding of some flat portion at the end of resetting response patterns in 12 VTs after procainamide indicates that the reentrant impulse conducts through fully recovered tissue within the circuit. It suggests that procainamide slowed these VTs by slowing conduction velocity in fully recovered tissue due to sodium channel blockade and not by prolongation of action potentials and refractory periods.


Asunto(s)
Frecuencia Cardíaca/efectos de los fármacos , Procainamida/farmacología , Taquicardia/fisiopatología , Estimulación Cardíaca Artificial , Estimulación Eléctrica , Electrocardiografía , Humanos
13.
Am J Cardiol ; 61(10): 770-4, 1988 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-3354439

RESUMEN

Single and double ventricular extrastimuli (VE) delivered during sustained, uniform ventricular tachycardia (VT) are able to reset or terminate the tachycardia. The relation between the coupling intervals of single and double VE resetting VT and those terminating it was examined in 80 uniform, morphologically distinct VT occurring in 52 patients. Of the 80 tachycardias receiving single VE, 41 were reset and 8 terminated. The corrected coupling interval of single VE first causing resetting was 0.81 +/- 0.08 compared with 0.66 +/- 0.06 for termination (p less than 0.001). Forty-two tachycardias received double VE with 33 being reset and 13 terminating. The corrected coupling interval of double VE at which resetting was first seen was 0.86 +/- 0.08 compared with 0.73 +/- 0.05 for termination (p less than 0.001). If the longest corrected coupling interval causing resetting was greater than or equal to 0.75, then 7 of 34 tachycardias terminated with single VE and 13 of 31 terminated with double VE compared with only 1 of 46 terminating with single VE and 0 of 10 with double VE if resetting was not observed by a corrected coupling interval of 0.75 (p less than 0.01 and p less than 0.02, respectively). If the longest corrected coupling interval at which resetting occurred was greater than or equal to 0.75, the predictive value for VT termination was 21% with single VE and 42% with double VE compared with only 2% with single VE and none with double VE if resetting was not observed by this corrected coupling interval.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Estimulación Cardíaca Artificial , Enfermedad Coronaria/complicaciones , Taquicardia/terapia , Electrocardiografía , Electrofisiología , Femenino , Sistema de Conducción Cardíaco/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Taquicardia/etiología , Taquicardia/fisiopatología
14.
Circulation ; 77(3): 569-80, 1988 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-3342488

RESUMEN

Transient entrainment was demonstrated during 59 pacing events in 18 episodes of sustained uniform ventricular tachycardia (VT) while recording electrograms from the site of origin of tachycardia (LE-SOO). During entrainment, the morphology of the initial component of the LE-SOO was identical to the morphology observed during the tachycardia in 13 VTs (group I), but in five VTs (group II), the initial component changed at a "critical" paced cycle length. The presence of the proposed surface electrocardiographic criteria for entrainment--fixed fusion and a first postpacing complex without fusion but occurring at the paced cycle length--were integrally dependent on the morphologic changes in the local presystolic electrogram. Fixed fusion of the surface electrocardiogram at one or more paced cycle lengths was detected during entrainment at 35 of 59 paced cycle lengths in 12 of 18 tachycardias, 10 of which were group I and two of which were group II VTs. Fixed fusion demonstrated by analysis of the LE-SOO was observed at one or more pacing cycle lengths in 17 of 18 VTs. In five tachycardias in which surface electrocardiographic fusion was not observed, fixed fusion was evident on analysis of the left ventricular LE-SOO during right ventricular pacing. The first postpacing interval, as measured at the surface electrocardiogram, was consistently equal to the paced cycle length in only one of 18 tachycardias and was greater than the VT cycle length in eight of 17 tachycardias. A pathway with a long conduction time was demonstrated during entrainment. However, in those 12 VTs in patients in whom pacing was performed at more than one cycle length and there was preservation of the LE-SOO morphology, the conduction time between the stimulus and presystolic electrogram remained constant. Thus, no evidence for "atrioventricular nodal-like" decremental conduction was observed over a wide range of pacing cycle lengths. We conclude that: (1) two of the previously proposed criteria for diagnosis of entrainment (fixed fusion on the surface electrocardiogram and a first postpacing interval equal to the paced cycle length) are overly restrictive criteria for definition of "entrainment" of VT, (2) analysis of endocardial recordings from the site of origin of tachycardia during attempted entrainment of VT is useful for documenting the presence of entrainment, and (3) such analysis provides a basis for the understanding of surface electrocardiographic phenomenon associated with entrainment.


Asunto(s)
Electrocardiografía , Sistema de Conducción Cardíaco/fisiopatología , Taquicardia/fisiopatología , Estimulación Cardíaca Artificial , Electrofisiología , Endocardio/fisiopatología , Humanos , Taquicardia/diagnóstico
15.
Circulation ; 77(3): 581-8, 1988 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-3342489

RESUMEN

The incidence and significance of fusion of the QRS complex during resetting of sustained ventricular tachycardias (VTs) was determined in 53 VTs induced by programmed stimulation in 46 patients with prior myocardial infarction. All 53 VTs were reset with one or two extrastimuli delivered at the right ventricular apex (RVA); 29 (54.7%) demonstrated fusion of the VT QRS complex coincident with the extrastimulus resetting the VT. Activation time at the RVA during VT (measured from the onset of the VT QRS complex to the first rapid deflection of the RVA electrogram) was longer in VT reset with fusion compared with those without fusion (91 +/- 30 vs 33 +/- 32 msec; p less than .001). A right bundle branch block VT QRS morphology and a rightward and inferior axis were more common in VT reset with electrocardiographic (ECG) fusion. Additionally, the shortest return cycle following the extrastimulus resetting the VT was shorter in VT reset with ECG fusion compared with those without (327 +/- 66 vs 423 +/- 84 msec; p less than .001). Fusion of the endocardial electrogram recorded at the site of VT origin was noted in 11 of 15 VTs that were reset while a recording catheter was positioned at this site, including all eight VTs with evidence of surface ECG fusion and three of seven VTs without fusion. Seventeen VTs were reset from the right ventricular outflow tract as well as the RVA; eight demonstrated QRS fusion at both sites, five from the right ventricular outflow tract only, and four from neither site.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Estimulación Cardíaca Artificial , Electrocardiografía , Sistema de Conducción Cardíaco/fisiopatología , Taquicardia/fisiopatología , Electrofisiología , Endocardio/fisiopatología , Humanos , Persona de Mediana Edad
17.
Am J Cardiol ; 60(7): 596-601, 1987 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-3630943

RESUMEN

UNLABELLED: To evaluate the influence of local tissue refractoriness and delay in intervening tissue on the ability of single ventricular extrastimuli to reset and characterize a resetting response pattern in ventricular tachycardia (VT), single ventricular extrastimuli were delivered during 81 VTs and double ventricular extrastimuli in 45 of the 81 VTs. Resetting of VT was recognized as a less than fully compensatory pause after stimulation and was seen in 43 of 81 VTs (53%) with single ventricular extrastimuli and 35 of 45 (78%) with double ventricular extrastimuli. Double ventricular extrastimuli reset 16 VTs not reset by single ventricular extrastimuli. The return cycle, the interval from the extrastimulus to the first VT beat after extrastimuli, has 1 of 3 distinct response patterns: flat, increasing, and flat plus increasing. In 19 VTs, resetting was seen with both single ventricular extrastimuli and double ventricular extrastimuli; 4 flat responses with single ventricular extrastimuli became flat plus increasing with double ventricular extrastimuli. All other patterns were unchanged. In the 19 VTs reset by both single and double ventricular extrastimuli, the estimate of both the total reset zone (94 +/- 36 vs 56 +/- 32 ms) and the flat portion of the reset zone (52 +/- 42 vs 42 +/- 28 ms) was significantly longer with double ventricular extrastimuli (p less than 0.001 and p less than 0.02, respectively). IN CONCLUSION: (1) when single ventricular extrastimuli failed to reset a VT, double ventricular extrastimuli from the same site may reset the VT.


Asunto(s)
Estimulación Cardíaca Artificial , Sistema de Conducción Cardíaco/fisiopatología , Taquicardia/terapia , Electrocardiografía , Electrofisiología , Humanos , Taquicardia/fisiopatología
18.
Am J Cardiol ; 58(10): 970-6, 1986 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-3776853

RESUMEN

Uniform, sustained ventricular tachycardia (VT) in the setting of prior myocardial infarction is believed to be due to reentry. The ability to reset VT with programmed extrastimuli requires that the premature impulse reach and enter the reentrant circuit. To evaluate the importance of the site of pacing on the ability to reset VT, single ventricular extrastimuli were delivered during 32 morphologically distinct, uniform VTs from both the right ventricular (RV) apex and RV outflow tract. Single ventricular extrastimuli resulted in resetting of VT from the RV apex only in 6 VTs, from the RV outflow tract only in 2, from both sites in 11 VTs and neither site in 13. When VT reset at both RV sites, 1 RV site or neither RV site was compared, a left bundle branch block VT QRS morphologic pattern was found to be more common in VT reset at both sites than at neither site (8 of 11 vs 4 of 13, p less than 0.05). No other differences in VT characteristics analyzed were found between these groups. Multiple ventricular extrastimuli were delivered in 16 VTs; in 6 of these, resetting was shown from at least 1 additional site, as compared to the response with single ventricular extrastimuli. In summary, site of stimulation can influence the ability of premature extrastimuli to reset uniform VT, and site dependence of VT resetting diminishes when multiple extrastimuli are used. This suggests that refractoriness or conduction delay in tissue between the pacing site and tachycardia circuit are important determinants of ability to reset VT from a particular site.


Asunto(s)
Estimulación Cardíaca Artificial , Taquicardia/terapia , Nodo Atrioventricular/fisiopatología , Bloqueo de Rama/fisiopatología , Bloqueo de Rama/terapia , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/complicaciones , Taquicardia/complicaciones , Taquicardia/fisiopatología
19.
Circulation ; 74(4): 722-30, 1986 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-3757186

RESUMEN

We analyzed the resetting response (a noncompensatory pause after electrical stimulation) during 37 hemodynamically tolerated ventricular tachycardias (VTs) induced by programmed electrical stimulation in 32 patients with chronic coronary artery disease. The mean cycle length of VT was 369 +/- 59 msec. Single extrastimuli were delivered at the right ventricular apex during all 37 VTs, and double extrastimuli were delivered at the same site during 23 VTs. The resetting response pattern was considered increasing, decreasing, or flat if the return cycle increased, decreased, or remained constant in response to progressively shorter coupling intervals of the extrastimuli. Ten VTs had an increasing pattern and nine a flat pattern. In 11 VTs the pattern was mixed (flat at longer coupling intervals and increasing at shorter ones), and in the remaining seven the pattern could not be defined. No VT had a decreasing pattern. The mean duration of the resetting interval (range of coupling intervals resulting in resetting) was 66 +/- 45 msec, or 17% of the cycle length of VT. VT with a mixed pattern had longer resetting intervals than VT with an increasing pattern (102 +/- 34 vs 64 +/- 40 msec; p less than .035); however, cycle lengths of VT were similar (370 +/- 58 vs 386 +/- 86, p = NS). An excellent correlation was observed between the shortest return cycles in response to single and double extrastimuli (r = .99), with a mean difference of 5 msec. The cycle length of VT exceeded the return cycle (measured to the QRS onset) during 15 VTs (41%).(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Sistema de Conducción Cardíaco/fisiopatología , Taquicardia/fisiopatología , Estimulación Cardíaca Artificial , Electrocardiografía , Ventrículos Cardíacos , Humanos , Estudios Prospectivos
20.
Am Heart J ; 112(3): 505-8, 1986 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-3751863

RESUMEN

A prospective study was undertaken to assess the response of patients with idiopathic dilated cardiomyopathy to programmed electrical stimulation (PES). Fifteen patients undergoing evaluation of congestive heart failure were studied. All patients underwent cardiac catheterization and coronary angiography as well as endomyocardial biopsy to exclude known causes of heart failure. No patient had a history of syncope or sustained ventricular arrhythmias. All patients were found to have severe left ventricular dysfunction (mean ejection fraction 17%), as well as nonsustained ventricular tachycardia on ambulatory monitoring or exercise testing. A protocol using up to two premature stimuli and burst pacing, from two right ventricular sites, induced up to four repetitive ventricular responses but failed to induce a sustained ventricular arrhythmia in any patient. Patients with dilated cardiomyopathy, advanced ventricular arrhythmias, and depressed left ventricular function respond differently than do patients with coronary artery disease, advanced ventricular arrhythmias, and depressed left ventricular function, to PES. PES appears to have limited value in the evaluation of patients with dilated cardiomyopathy and nonsustained ventricular arrhythmias.


Asunto(s)
Arritmias Cardíacas/diagnóstico , Estimulación Cardíaca Artificial , Cardiomiopatía Dilatada/complicaciones , Adulto , Arritmias Cardíacas/etiología , Femenino , Ventrículos Cardíacos , Humanos , Masculino , Persona de Mediana Edad , Pronóstico
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