RESUMO
Dual chamber pacemakers have inbuilt advanced safety systems such as ventricular safety standby (crosstalk detection) to prevent ventricular oversensing resulting in inappropriate pacing inhibition. We describe a case where this safety mechanism does not reliably work and the management required to rectify the situation in an educational format.
Assuntos
Bloqueio Atrioventricular/terapia , Dispositivos de Terapia de Ressincronização Cardíaca , Terapia de Ressincronização Cardíaca , Desfibriladores Implantáveis , Cardioversão Elétrica/instrumentação , Falha de Prótese , Potenciais de Ação , Bloqueio Atrioventricular/diagnóstico , Bloqueio Atrioventricular/fisiopatologia , Terapia de Ressincronização Cardíaca/efeitos adversos , Cardioversão Elétrica/efeitos adversos , Eletrocardiografia , Técnicas Eletrofisiológicas Cardíacas , Feminino , Frequência Cardíaca , Humanos , Pessoa de Meia-Idade , Desenho de Prótese , Fatores de Tempo , Resultado do Tratamento , Função Ventricular Esquerda , Função Ventricular DireitaRESUMO
Abrupt changes in heart rate, particularly short-long-short sequences in the ventricular cycle length (CL), might precede initiation of ventricular tachycardia/fibrillation (VT/VF). These changes may be facilitated or caused by pacing activity in patients with pacemakers or implantable-cardioverter defibrillators (ICDs). We describe a patient with two episodes of acquired VT precipitated by short-long-short sequences and diagnosed from the ICD recordings. In such cases, the knowledge of the device parameters is extremely important for a correct diagnosis and management.
RESUMO
In patients with an implantable cardioverter defibrillator, empirical antitachycardia pacing/burst pacing (ATP) is associated with a significantly decreased rate of appropriate shocks. The use of ATP as first-line therapy in ventricular tachycardia promotes less pain and better quality of life because the number of shocks is reduced. Additionally, battery longevity is substantially increased with this strategy. Based on this, device manufacturers have developed new algorithms to optimize the use of ATP and shocks in patients with an implantable cardioverter defibrillator. The present report describes a case in which the use of one of these new algorithms was associated with a significant delay in tachycardia termination and, consequently, led to syncope.
Assuntos
Estimulação Cardíaca Artificial , Desfibriladores Implantáveis , Síncope/etiologia , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/prevenção & controle , Idoso , Fibrilação Atrial/etiologia , Humanos , Masculino , Isquemia Miocárdica/complicações , Qualidade de Vida , Taquicardia Ventricular/fisiopatologia , Resultado do TratamentoRESUMO
Two cases of "locked-in" sensitivity in the managed ventricular pacing mode are reported. Patient A was a 22-year-old man with a history of hypertrophic obstructive cardiomyopathy and a prophylactic dual-chamber automatic implantable cardioverter-defibrillator who manifested paradoxic T-wave oversensing on the ventricular lead at a sensitivity setting of 1.2 mV but not earlier when the sensitivity had been set to 0.9 mV. Patient B was a 74-year-old patient with ischemic cardiomyopathy and a dual-chamber defibrillator who presented with persistent paradoxic undersensing of the P wave on the atrial lead even at the maximal sensitivity of 0.15 mV, although P-wave sensing was normal earlier when sensitivity was set to 0.3 mV. The phenomenon and the mechanism for its behavior are described.
Assuntos
Estimulação Cardíaca Artificial , Desfibriladores Implantáveis , Átrios do Coração/inervação , Ventrículos do Coração/inervação , Complexos Ventriculares Prematuros/terapia , Idoso , Cardiomiopatias/terapia , Cardiomiopatia Hipertrófica/terapia , Desenho de Equipamento , Falha de Equipamento , Átrios do Coração/patologia , Ventrículos do Coração/patologia , Humanos , Masculino , Período Refratário Eletrofisiológico , Adulto JovemRESUMO
Studies have shown that avoidance of right ventricular pacing results in a decrease in the incidence of atrial fibrillation and congestive heart failure. Newer algorithms which promote intrinsic conduction and decrease the frequency of ventricular pacing have been developed. However some of these new pacing algorithms are complex and can create potential pitfalls for the clinician. Additionally, these features may not be applicable to a reasonable amount of patients. We describe an example of a pacemaker pseudo-malfunction caused by one of these new algorithms.
Estudos mostram que reduzir o uso de estimulaГЦo ventricular direita em pacientes com marcapasso estА relacionado com menor incidЙncia de fibrilaГЦo atrial e insuficiЙncia cardМaca congestiva. Diante desse novo paradigma, as empresas fabricantes vЙm desenvolvendo novas estratИgias de programaГЦo com objetivo de minimizar a taxa de estimulaГЦo ventricular direita. Entretanto, esses novos modos de programaГЦo sЦo muitas vezes complexos, acarretando dЗvidas sobre o correto funcionamento desses dispositivos. AlИm disso, muitos dos novos modos de programaГЦo podem nЦo ser aplicАveis a uma parcela significativa dos pacientes. Apresentamos um exemplo de programaГЦo de marcapasso visando minimizar a estimulaГЦo ventricular direita, cujo resultado prАtico simula mau funcionamento do dispositivo.
