br Discussion False tendons are usually benign intraventricu

Discussion False tendons are usually benign, intraventricular myocardial structures, which may cause a musical murmur [1], rate-dependent ventricular extrasystoles, functional mitral regurgitation, or deformation of the LV cavity due to mechanical stretch and dilatation of the LV wall [1,2]. False tendons are elastic, especially in young patients, though with aging, may become rigid due to fibrosis and calcification [3–5]. As in the present case, false tendons may be associated with a hyperechoic shadow on transthoracic echocardiography. Because of the unchanged mid-septal dyssynchrony near the end of the false tendon during CRT, in oxymetazoline hydrochloride with the mitigation of intraventricular dyssynchrony near the base, we hypothesized that in this case, intraventricular dyssynchrony was caused by the CLBBB and the mechanical pressure exerted by the stiff false tendon on the weakened mid-septum during systole.
Conflicts of interest
Introduction A pacing circuit consists of a pulse generator and one or more leads that allow communication between the pulse generator and the heart. Some of the common reasons for noncapture include lead dislodgement or break in circuit, lead failure, and inflammation and fibrosis at the electrode-myocardium interface leading to a higher threshold for stimulation [1]. The usual treatment of a pocket infection involves removing the entire infected pacing system (pulse generator and leads); this reduces the risk of reinfection by 75% [2].
Case report The patient is a 64 year old female with dilated cardiomyopathy and complete heart block with pacemaker dependence. She was admitted for treatment of a pocket infection of her AICD (Automatic Implantable Cardioverter Defibrillator) system after an upgrade to a biventricular ICD. At her local hospital the pacemaker pocket was explored, and the pulse generator was removed, but the cardiologist was not able to remove the right ventricular lead. She was sent to a university center for extraction of the lead. A bipolar right ventricular active fixation lead coupled to a pulse generator taped to the patient׳s chest wall was used as her temporary pacing system. She was transferred back to her local hospital for antibiotics, and eventual implantation of a permanent pacing system. Several times, the patient developed symptomatic loss of capture of her temporary system. During one episode, she developed asystole, polymorphous ventricular tachycardia, and ventricular fibrillation requiring CPR and external cardioversion (Figs. 1 and 2). It was ultimately noted that the episodes of apparent malfunction of the temporary pacing system corresponded with nursing care in which the patient was receiving a bath or wound care. The pulse generator was being lifted off the patient׳s chest wall, resulting in episodes of loss of capture and asystole. It was also noted that the patient׳s pacemaker had been programmed to unipolar mode without the knowledge of the attending cardiologist. The system was reprogrammed to bipolar mode, and no subsequent episodes of loss of capture occurred.
Discussion The IPG׳s being out of contact with the skin is not an issue in a bipolar system. The reason is that the two electrodes on a bipolar lead make the circuit, and the IPG does not serve as the anode as the leads function to receive the impulse. In a bipolar pacing system, the lead tip is located at the distal portion of the interventricular septum, near the right ventricular apex. The impulse travels a short distance to the heart. In contrast, in a unipolar system, sensing of skeletal myopotentials, i.e. movement of the IPG against muscle, can generate electrical activity that may be missensed and cause potential pacemaker inhibition or failure to pace. In a bipolar system, in which the electrode leads are in very close proximity, sensing of noncardiac signals such as myopotentials or electromagnetic interference is less likely [1]. Hence, AICDs are used with bipolar leads so that it is less likely that a shock will be delivered after sensing an extracardiac signal.