Dual-chamber pacemaker malfunction mimicking atrial capture by the ventricular electrode.

A 78-year-old man came for a scheduled check up one month after the implantation of a permanent dualchamber pacemaker for symptomatic transient atrioventricular conduction disturbances (intermittent Mobitz II atrioventricular block). The patient's ECG indicated a loss of atrial capture by the atrial electrode with 1:1 atrioventricular conduction. A subsequent X-ray examination showed that both electrodes were well placed and in their correct sites. A detailed check of the pacemaker using the programmer, together with an echocardiographic examination, revealed the true nature of the malfunction: there was a significant delay between the atrial capture and atrial depolarisation and systole, as well as a loss of ventricular capture because of an acute increase in the threshold. Normal pacemaker function and pacing ECG were restored through modification of the pacemaker's functional parameters.

Three-dimensional echocardiographic documentation of pacemaker lead perforation presenting as acute pericarditis.

Myocardial perforation is a rare complication of permanent pacemaker insertion and is usually detected during the first month after implantation. Pericardial effusion often occurs at the same time, and as a consequence may generate difficulties in the diagnostic workup due to the various aetiologies of its origin. Computed tomography has been used for the documentation of lead perforation, but its diagnostic accuracy in comparison to echocardiographic examination has not been validated. We report a case of ventricular perforation causing pericarditis, initially undetected by computed tomography, that was finally diagnosed by means of real-time three-dimensional echocardiography.

Termination of ventricular tachycardia with antitachycardia pacing after ineffective shock therapy in an ICD recipient with hypertrophic cardiomyopathy.

Implantable Cardioverter Defibrillator (ICD) implantation is the only established therapy for primary or secondary prevention of sudden cardiac death in patients with Hypertrophic Cardiomyopathy (HCM). Ineffectiveness of shock therapy for the termination of potentially fatal ventricular arrhythmias in ICD recipients is rare in the presence of appropriate arrhythmia detection by the device. We report the case of a 48-year-old woman with HCM and a single chamber ICD, who received five inefficient high-energy (35 Joules) shocks for the termination of an appropriately detected episode of Ventricular Tachycardia (VT). The episode was safely terminated with a subsequent application of Antitachycardia Pacing (ATP) by the device. At the following ICD control, an acceptable defibrillation threshold was detected.

High power radiofrequency ablation of incessant atrioventricular re-entrant tachycardia in a patient with a Para-Hisian accessory pathway.

Radiofrequency ablation is the interventional therapy of choice for the definitive cure of patients with tachycardias facilitated by accessory pathways. Ablation of an accessory pathway at sites close to the His bundle is inevitably associated with an increased risk of causing complete atrioventricular block. Here we describe the case of a patient with pre-excitation syndrome and episodes of supraventricular tachycardia, in whom an electrophysiological study identified an accessory pathway so close to the His bundle that discrete sites between the pathway and the His bundle were extremely difficult to find. After a first, unsuccessful attempt at ablation the patient developed incessant supraventricular tachycardia. The accessory pathway was successfully ablated in a second session using high power radiofrequency current, although this entailed a great increase in the risk of causing complete atrioventricular block.

Contribution of electroanatomical mapping to the diagnosis of arrhythmogenic right ventricular cardiomyopathy in a patient with sustained ventricular tachycardia.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary cardiomyopathy, characterized mainly by anatomic and functional defects of the right ventricle. In many cases its diagnosis is quite difficult in spite of the existence of defined diagnostic criteria for the disease. We describe an interesting case of a patient with sustained ventricular tachycardia derived from the right ventricular outflow tract, in whom the diagnosis of ARVC was made with the contribution of electrophysiologic study and electroanatomical mapping, as the use of all other diagnostic tests and laboratory methods had left many unanswered questions. Based on our case, but also on other studies and case reports in the literature, we conclude that electroanatomical mapping is useful for the documentation of the diagnosis of ARVC, whenever this is not clear from the use of available diagnostic tests according to the defined criteria of the disease.