Right Leg Versus Left Peripheral Edema
We’ve already discussed some left vs. right cardiac issues. These included:
- Pleural effusions caused by cardiac conditions are always only on the right or bigger on the right. The exception? Pericardial disease can be associated with larger (and even left only) pleural effusions.
- Left carotid sinus pressure has a stronger effect on atrial-ventricular (AV) conduction than right carotid sinus pressure. ( The orignial version of this piece published November 14, 2023 incorrectly started the sentence with “right” carotid presure, which was not “right” — my apology.). So, if you want to block AV conduction to see if a regular tachycardia at around 150 beats per minute is atrial flutter, make sure you do left carotid pressure even if right-sided pressure didn’t work.
Here is another left vs right rule. Generalized peripheral edema should be greater in the left leg than in the right. That’s because:
1-the inferior vena cava is on the right side of the body making it a longer distance for blood return;
2- the right common iliac artery overlies the left common iliac vein and can compress the vein:
3-the left iliac vein has a higher incidence of venous webs, possibly produced by the repeated pulsations from the iliac artery.
These anatomic issues can produce occlusion of the deep left iliac system, called “May-Thurner syndrome”.* These issues are also why veno-occlusive disease is more common in the left leg.
The rule? Right only, or right-greater-than left peripheral edema, should always raise the possibility of right leg venous disease because generalized peripheral edema from issues like heart failure should be greater in the left leg..
· Sharafi S & Farsad K. Variant May-Thurner syndrome: Compression of the left common iliac vein by the ipsilateral internal iliac artery. Radiol Case Rep. 2018 Apr; 13(2): 419–423. PMID: 29904487
This is from my “500 Rules of Cardiology”, not really rules, not really 500, and quite presumptuous on my part, but they are simple sayings and principles I have used clinically and in teaching. Please share them with trainees and colleagues. I send them out to an email list so if you send me your friends’ email, I will add them to the list.
