Cardiac Resynchronization Therapy Periprocedural Care

Updated: Dec 17, 2014
  • Author: Adam S Budzikowski, MD, PhD, FHRS; Chief Editor: Richard A Lange, MD, MBA  more...
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Periprocedural Care


Multiple sheaths are currently available for obtaining access to the coronary sinus. The various delivery systems differ with regard to shape and especially with regard to size. For example, the delivery system manufactured by Pressure Products (San Pedro, CA) allows the delivery of a 6F pacing lead via the inner catheter, whereas the other systems allow delivery of only 4F leads.

Selection of pacing leads should be dictated predominantly by the anatomy of the branch and the ease of deliverability. Bipolar leads are used in most cases, with unipolar leads reserved for patients with extremely small branches (ie, branches that are too small to accommodate a 4F bipolar lead). In Europe, multipolar leads with 4 separate pacing electrodes are available; these have been associated with improved implantation success. [13]

Left ventricular pacing leads are typically secured either with active fixation using tines or with passive fixation using the multiple curves of the lead to fit it tightly in the target vein. An active-fixation unipolar lead is available whose tines can be extended from the body of the lead (proximal to the pacing port) and retracted if repositioning is necessary.

Leads from different manufacturers have not only different fixation curves but also different pacing electrode spacing. Wider pacing electrode placement improves lead capture and electronic repositioning (ie, changing the pacing vector) but also increases the risk for diaphragmatic capture.


A pacemaker is an electronic device, approximately the size of a pocket watch, that senses intrinsic heart rhythms and provides electrical stimulation when indicated. Cardiac pacing can be either temporary or permanent.

Permanent pacing is most commonly accomplished through transvenous placement of leads to the endocardium (ie, right atrium or ventricle) or epicardium (ie, to the left ventricular surface via the coronary sinus), which are subsequently connected to a pacing generator placed subcutaneously in the infraclavicular region.

Permanent pacemakers are implantable devices that sense intrinsic cardiac electric potentials and, if these are too infrequent or absent, transmit electrical impulses to the heart to stimulate myocardial contraction. A specialized type of pacemaker therapy, cardiac resynchronization therapy (CRT) with biventricular pacing, with or without an implantable cardioverter-defibrillator (ICD), has been used as adjunctive therapy in patients with heart failure.

For more information, see the article Implantable Pacemakers.

Implantable Defibrillators

The ICD is first-line treatment and prophylaxis in patients at risk for ventricular tachycardia (VT) or ventricular fibrillation (VF). Current devices offer tiered therapy with programmable antitachycardia pacing schemes, as well as low-energy and high-energy shocks in multiple tachycardia zones.

Dual-chamber, rate-responsive bradycardia pacing is now available in all ICDs, and sophisticated discrimination algorithms minimize shocks for atrial fibrillation, sinus tachycardia, and other non–life-threatening supraventricular tachyarrhythmias. Diagnostic functions, including stored electrograms, allow for verification of shock appropriateness.

For more information, see the article Implantable Defibrillators.