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Patient: Male, 60 y/o. Medical history unknown.
ECG description:
- Sinusbradycardia at 46 bpm
- Normal cardiac axis. Approx. 30°
- AV Junctional Escape Complex
- Left Bundle Branch Block. Q
- T inversion in lead III and biphasic T wave in lead aVF.
ECG comments:
Supraventricular escape complexes are usually precipitated by long pauses, such as sinus arrest, intermittent SA block or long postextrasystolic pauses. Slow phases in sinus bradycardia however is also a common cause of such escape beats. The last QRS complex in this ECG is preceded by an inverted P wave in the inferior leads. The PR interval is also shorter. These morphologic clues tell us that the atria is depolarized retrogradely. The depolarization wave spreads away from leads II, III and aVF, making the P wave inverted. The shortened PR interval indicates an ectopic focus located closer to the AV node.
January 29, 2009
Patient: n/a
ECG description:
- Sinus rhythm at 85 bpm
- Ventricular extra systoles in trigeminy pattern. Every third beat is a Premature Ventricular Complex (PVC).
- Marked First Degree AV Block. PR interval is 310 ms.
- Incomplete Left Bundle Branch Block (LBBB). QRS width 100ms.
- Axis normal at approx. 60°
ECG diagnosis: Ventricular trigeminy with marked (severe) 1° AV Block and incomplete LBBB.
ECG Comments:
PVC TRIGEMINY: When every third beat is a PVC, the term trigeminy is used. The PVCs here are unimorph and therefore unifocal, which means they all have the same morhpology and therefore arise from the same ectopic focus. Premature beats originates in irritable autmaticity foci that fires spontaneously. Such beats come earlier than expected in the rhythm. It is also important to understand that although PVCs in many ways are considered to be benign, they are early signs of hypoxia. 6 PVCs per minute is considered pathological. Remember that a continuous run of bigeminy or trigeminy will quickly exceed that criteria, and will then usually indicate that a very irritable focus is hypoxic and needs attention.
1° AV BLOCK: The PR interval in this ECG is 310ms. This is a so called marked First Degree AV Block. This term indicates that the PR interval is markedly prolonged. This is noted because sometimes the AV conduction delay becomes so severe that pacemaker insertion may be needed. I am not completely sure about the exact criteria here, but from what I have read permanent pacing is indicated when the patient is symptomatic and when the PR interval exceeds 300ms. This article from Emergency Medicine News discusses the matter, and says that those with a PR interval >300ms are at risk of developing complete heart block.
INCOMPLETE LBBB: The morphology here resembles LBBB, but the QRS is only 100ms. To diagnose BBB, the QRS complex must be at least 120 ms. Therefore, this LBBB must be considered incomplete.
November 19, 2008