Fig 1.b
Same patient a few hours later, following the insetion of a permanent pacemaker. The sinus rhythm is conducted with RBBB distorted by pacemaker spikes (pseudofusion beats). Shorter-paced AV interval vould have resulted in haemodynamically less favourable LBBB-like ventricular pacing or true fusion sinus-pacemaker QRS complexes. [! XE "pseudofusion beats" !]