The Patient: This ECG was taken from an elderly woman. Unfortunately, we do not know any details about the case. That acknowledged, there are many interesting aspects to this ECG.
The ECG: The first thing we notice is the severe bradycardia – almost certain to be symptomatic. The rate is 32 bpm and the rhythm is regular. There are no P waves. This is a junctional rhythm, slightly slower than expected from junctional escape.
The QRS shows the presence of right bundle branch block. Each QRS on the ECG starts as a narrow complex, but then adds an “extra” wave onto the end – the delay caused by the right ventricle depolarizing late. The terminal delay is very noticeable in V1 as an R’ wave, and in Leads I and V6 as a small, wide s wave. There is right axis deviation, so the diagnosis of bifascicular block (RBBB and left posterior fascicular block) can be made.
V2 through V6 show fragmentation of the QRS complexes and a loss of voltage and R wave progression. This points to anterior wall M.I. We can’t know the age of the M.I. without clinical correlation, but the ST segments in those leads are very flat, with uniformly symmetrical inverted T waves all the way to V6. All of these signs indicate recent injury. An anterior M.I. can cause the bifascicular block we are seeing, since the bundle branches begin in the septum.
Our patient has a host of conduction system problems: there is no sign of sinus node activity, the junctional escape rhythm is slow even for the junction, there is a right bundle branch block, and the left posterior fascicle is blocked. Many diseases can cause these conduction system failures, including M.I. as well as diseases causing inflammation and fibrosis of tissues. Finding the underlying cause(s) of all these abnormalities is very important, but the FIRST consideration should be protecting perfusion by insuring an adequate rate. This patient is certainly a candidate for a pacemaker, with her bradycardia and the fact that she is living with only one main fascicle in her bundle branches (the anterior-superior fascicle).
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