Rhythm is regularly irregular with a sinus complex followed by an early qrs complex that has a negative p wave in leads 2 and aVF. These are PACs in a bigeminal pattern. At end is NSR.

Coarse AF (atrial waves are irreg in morphology, amplitude and intervals) with QRS complexes at a regular rate, ie regularized AF which is due to complete heart block. The escape rhythm is junctional and hence the CHB is due to AV nodal block.

Atrial tachy with 5:4 Wenckebach. Nonspecific ST-T wave changes.

Narrow complex regular Supravent tachy arrhythmia at a rate of 270 bpm. The only supravent rhythm at this rate is atrial flutter with 1:1 conduction. Also noted is electrical or QRS alternans. The j point depression and st depression may be due the superimposed flutter wave.

short rp supraventricular tachycardia. This is not sinus but may be junctional or atrial. Since it terminates with a non conducted p wave this indicates that this is a junctional tachycardia. Hence this is a typical avnrt.

Biventricular pacemaker. It is tracking an atrial tachycardia that has a rate of 220 bpm. Pacemaker function is A sensed V paced but as atrial rate is greater than upper rate limit of pacemaker only every other p wave is sensed and hence vent pacing rate is 110 bpm.

At end of the ecg there is NSR with 2:1 block (which can be either mobitz type 1 or type 2. QRS has lbbb. At beginning there is chb with an escape ventricular rhythm. Hence the 2:1 av block is mobitz type 2.

NSR with WPW. Note at end PR interval shortens and delta wave more prominent. This is termed “concertina effect” resulting from changes in av conduction velocity-when faster less preexcitation and when slower more preexcitation. Most frequent arrhythmia with WPW is avrt.

The ecg provides evidence of myocardial abnormalities or hypertrophy and not chamber size or enlargement. This is diagnosed by an echo other imaging such as x-ray, ct scan or mri. Hence enlargement is not an appropriate ecg term.