S1
Abbreviation with 2 meanings
| Stands for | First heart sound |
|---|---|
| Meanings | 2 |
| Categories | Medical |
S1 has two meanings. It stands for First heart sound (cardiology) or First sacral vertebra or nerve root (anatomy).
Meanings of S1 at a glance
| # | S1 stands for | Context |
|---|---|---|
| 1 | First heart sound | Medical › Cardiology |
| 2 | First sacral vertebra or nerve root | Medical › Anatomy |
1. First heart sound
Medical · Cardiology Abbreviations
The "lub" of the heartbeat, produced by closure of the mitral and tricuspid valves at the start of ventricular systole and best heard at the apex. Its loudness changes with valve disease and with the PR interval.
Example: Loud S1 and an opening snap at the apex in a patient with rheumatic MS.
S1 is loud in mitral stenosis and with a short PR interval, soft with a long PR interval or severe mitral regurgitation, and varies from beat to beat in complete heart block and atrial fibrillation. Its normal split is subtle. Outside cardiology S1 commonly means the first sacral vertebra or spinal nerve.
2. First sacral vertebra or nerve root
Medical · Anatomy Abbreviations
Uppermost segment of the sacrum, and the nerve root that exits through the first sacral foramen. The S1 root supplies the calf muscles (plantar flexion), the ankle (Achilles) reflex and sensation along the outer foot and sole.
Example: Decreased sensation of the lateral foot and 1+ ankle jerk, consistent with S1 radiculopathy.
Clinicians test S1 strength by having patients walk on their toes or perform single-leg heel raises. The roots from S2 to S4 control bladder, bowel and sexual function, so saddle numbness with urinary retention suggests cauda equina syndrome, a surgical emergency. In cardiology S1 means the first heart sound.
Related abbreviations
More cardiology abbreviations
- RVR – Rapid ventricular response
- RVSP – Right ventricular systolic pressure
- RWMA – Regional wall motion abnormality
- S-ICD – Subcutaneous implantable cardioverter-defibrillator
- S2 – Second heart sound
- S3 – Third heart sound
- S4 – Fourth heart sound
- SA – Sinoatrial
See all 229 cardiology abbreviations →
More anatomy abbreviations
- PT – Posterior tibial (artery or pulse)
- RC – Rotator cuff
- RLQ – Right lower quadrant
- RUQ – Right upper quadrant
- SB – Small bowel
- SCM – Sternocleidomastoid (muscle)
- SFA – Superficial femoral artery
- SI – Sacroiliac (joint)
See all 70 anatomy abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.