5
Definitions
Table 1. Definitions
Term Definition
LBBB For the purposes of this guideline, LBBB is defined by the 2009
AHA/ACCF/HRS Scientific Statement on recommendations for the
standardization and interpretation of the electrocardiogram (ECG)
as QRS duration ≥120 ms and a broad notched or slurred R-wave in
leads I, augmented Vector Le (aVL), V
5
, and V6.
CPP CPP is defined as any form of cardiac pacing intended to restore or
preserve ventricular synchrony. CPP can be achieved by engaging the
intrinsic conduction system via CSP (eg , HBP or LBBAP) or CRT.
CSP CSP involves recruitment of the intrinsic conduction system by either
HBP or LBBAP.
HBP HBP involves the direct stimulation of the His bundle to engage the
native conduction system. Based on location and pacing outputs,
HBP may be selective (isolated recruitment of the His bundle) or
nonselective (ns) (recruitment of both the local septal myocardium
and the His bundle).
LBBAP LBBAP is ventricular pacing that is intended to engage all or any part
of the le bundle branch (LBB) fascicular system. Similar to HBP,
various responses can be seen based on location and pacing outputs.
ese include selective le bundle branch pacing (LBBP) (direct
stimulation and isolated recruitment of the LBB fibers), nonselective
LBBAP (direct stimulation and recruitment of both the local
myocardium and the LBB fibers), or deep septal pacing (no direct
recruitment of the LBB fibers).
CRT CRT aims to restore or preserve ventricular synchrony using LV
stimulation at appropriately timed RV sensing or stimulation. CRT
most commonly refers to BiV pacing, in which a pacing lead is
implanted in the RV and another on the epicardial surface of the LV
via an epicardial vein. Alternatively, the LV lead may be implanted
endocardially or surgically on the epicardium. LV pacing alone in some
situations may also deliver CRT. CSP for patients with dyssynchrony
may also be considered a form of CRT, but for the purposes of this
guideline, CRT refers to use of BiV or LV pacing. ese pacing locations
refer to standard anatomy but may differ in certain forms of CHD.
BiV pacing BiV pacing is the most common method used to achieve CRT. It most
commonly involves the use of 2 ventricular leads, 1 in the RV (apex
or septum) and 1 to pace the LV via the CS or sometimes via direct
placement on the epicardium or endocardium. e LV lead is usually
implanted epicardially in the coronary veins, ideally targeting an area of
latest activation, which is most oen the lateral or posterolateral wall.
Alternatively, the LV lead may be implanted endocardially or surgically
on the LV epicardium.
