Sinus venosus atrial septal defect: a rare cause of misplacement of pacemaker leads

The Sinus Venosus Veno-Venous Bridge: Not a septal defect

This review provides an update on the morphology of the sinus venosus defect. It was earlier believed that a 'common wall' separated the right pulmonary veins from the superior caval vein. In the sinus venosus defects, this wall was absent. Current evidence shows that the superior rim of the oval fossa, rather than forming a second septum or representing a common wall, is an infolding between the walls of the caval veins and the right pulmonary veins. The sinus venosus defect is caused by the anomalous connection of one or more pulmonary veins to a systemic vein. However, the pulmonary vein(s) retain their left atrial connections, leading to a veno-venous bridge that allows interatrial shunting outside the oval fossa. True atrial septal defects are located within the oval fossa or in the anteo-inferior buttress, while sinus venosus defects, ostium defects and coronary sinus defects are morphologically distinct from them.

Shift From Left to a Right Bundle Block on ECG Leading to the Diagnosis of a Malpositioned Lead in the Coronary Sinus: A Case Report

On electrocardiography (ECG), ventricular pacing appears as a spikes that precede induced QRS complexes. The induced complexes with a right ventricular lead have the morphology of a left bundle branch block (LBBB). We describe a case of malposition right ventricular (RV) lead in the coronary sinus diagnosed based on the changes noted in the ECG tracing. An 80-year-old man with a pacemaker implanted for high-grade AV block was found unresponsive. Six minutes of cardiopulmonary resuscitation resulted in return of spontaneous circulation. The ECG demonstrated a new paced right bundle branch block (RBBB) pattern. Chest radiography revealed a misplaced right ventricular (RV) lead in the coronary sinus which was confirmed by 2D-echocardiography. The patient's healthcare proxy (HCP) declined invasive interventions. The patient expired due multiorgan failure secondary to ventilator associated pneumonia. When an RBBB pattern is seen with RV pacing, patients must be evaluated for mispositioning of the RV lead navigation through an atrial septal defect (ASD) or perforation of the ventricular septum, aberrant retrograde conduction, pre-existing right bundle disease and the "pseudo-RBBB" pattern (seen with the ventricular lead placed in the RV apex/distal septum). A frontal axis of 0° to 90° and precordial transition by lead V3 differentiates RV septal pacing from all fonns of LV pacing, including lead placement in the coronary sinus. Our patient had precordial transition at V3.

Chronic lead malposition diagnosis and management: discussion of two cases and literature review

Management of lead malposition is crucial to avoid complications and is carried out on case-by-case bases. The 12-lead ECG during pacing and chest X-ray are essential during initial workup and recommended for new patients to the device clinic. Echocardiography and CT scan are important to confirm the location and plan appropriate therapy.