Diego Chemello

Cardiac arrest caused by undersensing of a temporary epicardial pacemaker.

The R-on-T phenomenon is a well-known entity that predisposes to dangerous arrhythmias. Typically, a premature ventricular complex occurring at the critical time during the T wave of the preceding beat precipitates ventricular tachycardia and fibrillation. This phenomenon can occur not only in asynchronous ventricular pacemakers, but also in synchronous pacemakers, if loss of sensing of the intrinsic rhythm becomes evident. A patient who was fitted with a temporary epicardial wire, following cardiac surgery and experienced repeated episodes of polymorphic ventricular tachycardia caused by the R-on-T phenomenon, is described.

Twiddler syndrome with 180° rotation of an implantable cardioverter defibrillator generator resulting in malfunction of one of the shocking coils

A 78-year-old woman with non-ischaemic cardiomyopathy received a prophylactic single-chamber implantable cardioverter defibrillator (ICD) and later underwent device replacement for battery depletion (Current VR, St Jude Medical Inc., …

Right ventricular perforation by a passive-fixation pacemaker lead

La perforación ventricular subaguda es una complicación rara del implante de marcapasos o desfibrilador cardioversor implantable (DCI). Entre tanto, puede ser potencialmente fatal. El desarrollo de cables electrodos de fijación activa de pequeños diámetros puede estar asociado al aumento de riesgo de perforación tardía ventricular. Además de eso, el tratamiento de esa complicación ha sido poco descripto. Reportamos un caso poco usual de perforación subaguda de ventrículo derecho, causada por un cable electrodo de fijación pasiva. Perforación del Ventrículo Derecho por Cable de Marcapasos de Fijación PasivaPalavras-chave Ventrículos do coração/lesões; ventrículo direito/lesões, ferimentos e lesões; ferimentos perfurantes. Perfuração ventricular subaguda é uma complicação rara do implante de marca-passo ou desfibrilador cardioversor implantável (DCI). Entretanto, ela pode ser potencialmente fatal. O desenvolvimento de cabos-eletrodos de fixação ativa de pequenos diâmetros pode estar associado com o aumento de risco de perfuração tardia ventricular. Além disso, o tratamento dessa complicação tem sido pouco descrito. Reportamos um caso pouco usual de perfuração subaguda de ventrículo direito, causada por um cabo-eletrodo de fixação passiva. Subacute ventricular perforation is a rare complication of pacemaker or implantable-cardioverter defibrillator implantation. However, it can be life threatening. The development of small-diameter active fixation leads may be associated with increased risk for delayed right ventricular perforation. Additionally, the management of this complication has been poorly described. We report an unusual case of subacute right ventricular perforation caused by a passive fixation lead. Perfuração do Ventrículo Direito por Cabo de Marca-passo de Fixação Passiva

Ventricular Tachycardia Precipitated by Short-long-short Sequence in a Patient with Implantable-cardioverter Defibrillator.

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.

Apparent pacemaker malfunction following atrioventricular node ablation

61-year-old woman received backup ventricular pacing and atrioventricular (AV) node ablation for chronic atrial fibrillation with poor ventricular rate control. Following uneventful single-chamber pacemaker implantation (Sensia; Medtronic Inc, USA), AV node ablation was performed, which resulted in complete AV block with ventricular escape rates of 35 beats/min to 40 beats/min. A lower pacemaker rate was then programmed in VVI mode (95 beats/min lower heart rate) to prevent bradycardia, a potential trigger for torsades de pointes (1). During postprocedure monitoring, telemetry recordings showed multiple episodes of long pauses with no pacing output (Figure 1). The pacemaker pacing and sensing parameters, and lead and impedance, even with pacemaker pocket manipulation, were normal. Analysis of the tracing showed that the pauses between the intrinsic R wave and the paced beat were exactly 1200 ms. Also, the pauses between any two intrinsic R waves remained less than 1200 ms. There were no pauses following paced beats. These findings suggested that the hysteresis feature had been left on at a rate of 50 beats/min, which was confirmed. The patient had regained some degree of AV nodal conduction and her intrinsic R waves appeared intermittently at shorter cycle lengths than the lower rate interval, which triggered the hysteresis feature and caused the pauses. This feature was switched off and no pauses were documented subsequently. Hysteresis programmed on would not be a problem in a pacemakerdependent patient with complete AV block and low ventricular escape rates. However, if AV nodal conduction recovers, as in the present patient, hysteresis could be the cause of cardiac pauses, a potential trigger for life-threatening torsades de pointes. imAges in cArdiology

Postoperative atrial flutter: circuit in the right or left atrium?

A 65-year-old woman was referred for electrophysiologic study and catheter ablation for recurrent episodes of atrial flutter. She had undergone open-heart surgery for left atrial myxoma. During the surgical procedure, the tumor that was attached to the inferior portion of the interatrial septum and the inferolateral wall of the left atrium was completely excised. Free left atrial wall and interatrial septum were reconstructed using pericardial patches. The 12-lead electrocardiogram and intracardiac electrograms at baseline with standard catheter positions are shown in Figures 1 and 2, respectively. The distal pole of the 20-pole catheter in the right atrium is not in contact with the right atrial wall. Is the flutter circuit in left or right atrium?

Health Care Utilization following Ventricular Tachycardia Ablation: A Propensity Score Matched Cohort Study

BACKGROUNDnCatheter ablation of ventricular tachycardia (VT) can reduce the burden of ventricular arrhythmia (VA) but its effect on health care utilization and costs after such therapy is poorly known. We sought to compare the rates of cardiovascular (CV)-related hospitalizations, survival, and health care costs in patients with recurrent VT treated either with VT ablation or with medical therapy.nnnMETHODSnOne-hundred implantable cardioverter-defibrillator patients with structural heart disease who underwent VT ablation were included. Propensity score-matched patients with recurrent VT treated with medical therapy were identified from a prospective registry of approximately 7000 de novo implantable cardioverter-defibrillator patients. Outcomes and costs were ascertained using health administrative databases.nnnRESULTSnAmong patients who underwent VT ablation, the cumulative rates of VA-related hospitalizations were lower in the 2 years after their ablation procedure compared with the year before (rate ratio, 0.3; 95% confidence interval [CI], 0.22-0.43). Rates of CV-related hospitalization and hospitalization because of VA post index date were similar between the VT ablation and medical therapy groups (hazard ratio [HR], 0.94; 95% CI, 0.57-1.54 and HR, 1.04; 95% CI, 0.57-1.91, respectively). Health care costs in the VT ablation patients were not increased post-ablation compared with the medical management group. The risk of all-cause mortality was lower among patients in the VT ablation group relative to the medical therapy group (HR, 0.64; 95% CI, 0.4-0.99).nnnCONCLUSIONSnPatients who underwent VT ablation experienced a significant reduction in their rate of VA-related hospitalizations. Patients treated with VT ablation had similar rates of CV-related hospitalization compared with those treated with medical therapy without increased health care-related costs.

Perforación del ventrículo derecho por cable de marcapasos de fijación pasiva

La perforación ventricular subaguda es una complicación rara del implante de marcapasos o desfibrilador cardioversor implantable (DCI). Entre tanto, puede ser potencialmente fatal. El desarrollo de cables electrodos de fijación activa de pequeños diámetros puede estar asociado al aumento de riesgo de perforación tardía ventricular. Además de eso, el tratamiento de esa complicación ha sido poco descripto. Reportamos un caso poco usual de perforación subaguda de ventrículo derecho, causada por un cable electrodo de fijación pasiva. Perforación del Ventrículo Derecho por Cable de Marcapasos de Fijación PasivaPalavras-chave Ventrículos do coração/lesões; ventrículo direito/lesões, ferimentos e lesões; ferimentos perfurantes. Perfuração ventricular subaguda é uma complicação rara do implante de marca-passo ou desfibrilador cardioversor implantável (DCI). Entretanto, ela pode ser potencialmente fatal. O desenvolvimento de cabos-eletrodos de fixação ativa de pequenos diâmetros pode estar associado com o aumento de risco de perfuração tardia ventricular. Além disso, o tratamento dessa complicação tem sido pouco descrito. Reportamos um caso pouco usual de perfuração subaguda de ventrículo direito, causada por um cabo-eletrodo de fixação passiva. Subacute ventricular perforation is a rare complication of pacemaker or implantable-cardioverter defibrillator implantation. However, it can be life threatening. The development of small-diameter active fixation leads may be associated with increased risk for delayed right ventricular perforation. Additionally, the management of this complication has been poorly described. We report an unusual case of subacute right ventricular perforation caused by a passive fixation lead. Perfuração do Ventrículo Direito por Cabo de Marca-passo de Fixação Passiva

Perfuração do ventrículo direito por cabo de marca-passo de fixação passiva

La perforación ventricular subaguda es una complicación rara del implante de marcapasos o desfibrilador cardioversor implantable (DCI). Entre tanto, puede ser potencialmente fatal. El desarrollo de cables electrodos de fijación activa de pequeños diámetros puede estar asociado al aumento de riesgo de perforación tardía ventricular. Además de eso, el tratamiento de esa complicación ha sido poco descripto. Reportamos un caso poco usual de perforación subaguda de ventrículo derecho, causada por un cable electrodo de fijación pasiva. Perforación del Ventrículo Derecho por Cable de Marcapasos de Fijación PasivaPalavras-chave Ventrículos do coração/lesões; ventrículo direito/lesões, ferimentos e lesões; ferimentos perfurantes. Perfuração ventricular subaguda é uma complicação rara do implante de marca-passo ou desfibrilador cardioversor implantável (DCI). Entretanto, ela pode ser potencialmente fatal. O desenvolvimento de cabos-eletrodos de fixação ativa de pequenos diâmetros pode estar associado com o aumento de risco de perfuração tardia ventricular. Além disso, o tratamento dessa complicação tem sido pouco descrito. Reportamos um caso pouco usual de perfuração subaguda de ventrículo direito, causada por um cabo-eletrodo de fixação passiva. Subacute ventricular perforation is a rare complication of pacemaker or implantable-cardioverter defibrillator implantation. However, it can be life threatening. The development of small-diameter active fixation leads may be associated with increased risk for delayed right ventricular perforation. Additionally, the management of this complication has been poorly described. We report an unusual case of subacute right ventricular perforation caused by a passive fixation lead. Perfuração do Ventrículo Direito por Cabo de Marca-passo de Fixação Passiva