Knowing What Should Be Right…From Left

Below is one of 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 colleague. If you send me their emails, I can add them to the list.

Knowing What Should Be Right From Left…At Least With Pleural Effusions — Pleural effusions caused by heart disease, usually heart failure, are always right sided and if bilateral are always bigger on the right. In fact, if you see only a left pleural effusion, you should look for a non-cardiac cause. But there are two exceptions besides situs inversus. You can have a left-sided-only effusion after cardiac surgery, but that seems pretty obvious. You can also have only a predominantly left-sided effusion in pericardial disease. David Spodick, MD, (1927–2019), a pericardial disease expert in Boston and Worcester, MA, reviewed 133 consecutive patients discharged with the diagnosis of pericardial disease.* Of these 35 had a pleural effusion. Those effusions were only left-sided in 21, greater on the left in 4, and equal right/left in 7. Only 2 had a right effusion greater than the left and only 1 had only a right effusion. Some of those with predominant right effusions may have also had heart failure, which could have affected the results.* There are two rules here: Cardiac effusions are predominantly right-sided and think of pericardial disease if there is cardiac disease with a predominantly left pleural effusion.

*Weiss JM, Spodick DH. Association of left pleural effusion with pericardial disease. N Engl J Med. 1983 Mar 24;308(12):696–7.