Second-degree AV block, Mobitz I
Palpitations and Low Back Pain
A 49-year-old man presents with palpitations, weakness, and low back pain.
Look for
- Progressive PR lengthening within a sequence.
- A P wave is not followed by a QRS.
- Shorter PR when conduction resumes.
Where to look. Follow P waves and PR intervals on a long strip, in II or whichever lead best shows P.
Conduction delay increases until an impulse fails to conduct, then the cycle repeats. This is often nodal, but the tracing does not always locate the block.
Evaluation shows endocarditis with a subvalvular abscess; this setting means the conduction disturbance must not be dismissed.
References & provenance
The ECG Made Easy, 9e, ch. 3, PDF 71–75; Lilly, 6e, ch. 12, p. 291–292.
Pranitha Kovuri; Sriviji Senthil Kumaran; Tulika Chatterjee; Alexander Muacevic; John R Adler. Streptococcus sanguinis Endocarditis of Bicuspid Aortic Valve Presenting as Septic Arthritis of Lumbar Facet Joint. 2022. doi:10.7759/cureus.24189. Figure 1. CC BY 4.0. CC BY 4.0
Adaptation: cropping and removal of headers/annotations outside the tracing where applicable; metadata removed. Waveforms have not been redrawn.
Compared with the published source; no independent clinical validation is claimed.
Original annotations & limitations
BAV du deuxième degré, Mobitz I
Homme de 49 ans; palpitations, faiblesse et lombalgie; endocardite avec abcès sous-valvulaire documentée au bilan.
Préserver l’activité atriale visible et vérifier manuellement le raccourcissement PR après la pause.