Cardiac Resynchronization Therapy


Practice Essentials

Cardiac resynchronization therapy (CRT), additionally referred to as biventricular pacing or multisite ventricular pacing, includes simultaneous pacing of the proper ventricle (RV) and the left ventricle (LV). In addition to a traditional RV endocardial lead (without or with a proper atrial [RA] lead), CRT includes an extra coronary sinus lead positioned for LV pacing.


A pacemaker is a digital tool, about the size of a pocket watch that senses intrinsic coronary heart rhythms and gives electric stimulation while indicated. Cardiac pacing can be either temporary or permanent.

 Permanent pacing is maximum normally completed thru transvenous placement of results in the endocardium (ie, RA or RV) or epicardium (ie, the LV floor through the coronary sinus [CS]), which can be finally linked to a pacing generator located subcutaneously withinside the infraclavicular region.

 CRT is a specialised form of pacemaker remedy that gives biventricular pacing. This is finished without or with using an implantable cardioverter-defibrillator (ICD), a tool hired for remedy and prophylaxis in sufferers at threat for ventricular tachycardia (VT) or ventricular fibrillation (VF).


Access to the CS for implantation of the LV lead can be accomplished through the axillary, subclavian, or cephalic vein.

To facilitate strong LV lead placement, it's far sensible first to area the RV pacing lead after which to enhance the LV lead into the CS branch, leaving the sheath in the area. After the RA lead is positioned, the LV lead guiding sheath is removed, and the LV lead is sutured in the area.

RV lead

In maximum cases, the transport machine sheath is exceeded over a guidewire into the RA after which superior slowly into the RV, wherein 90°-180° of counterclockwise rotation is eventually carried out at the same time as the sheath is lightly withdrawn after which superior. This manoeuvre commonly brings the sheath to the CS or the region of the CS os, permitting clean cannulation of the CS with a guidewire.

LV lead

Although it could be viable to area the LV lead without understanding the anatomy of the CS and its branches, it's miles prudent to reap a CS phlebogram to direct the choice and site of this lead.

Successful resynchronization may be executed with the placement of the LV lead in nearly any CS department, supplied that the web website online is withinside the proximal 0.33 to the centre 0.33 of the LV.

Several strategies had been defined for department cannulation, together with the following:

  • Branches with acute-perspective origins can regularly be cannulated with an angioplasty cord with no difficulty.
  • If a department originating at a proper or obtuse perspective is hard to cannulate, an internal catheter can be inserted close to the preselected department in order that the guidewire may be superior into the department; as soon as that is accomplished, the catheter can be exchanged for a packing lead whilst the cord role is maintained.
  • Alternatively, in such difficult cases, a larger-lumen internal catheter can be used to permit transport of the pacing lead; this approach has been simplified with the aid of using the usage of a lead with an exaggerated curve, via which a stylet or angioplasty guidewire is superior to direct the lead tip into the ideal venous department.

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With Regards,
Jessica Lopez
Journal of Cardiac and Pulmonary Rehabilitation