Early in my training as a medical student and intern, it seemed that all people ever cared about on an echo report was the “EF!” This refers to the left ventricular ejection fraction (LVEF) – the percentage of the left ventricle’s diastolic blood volume that is pumped out after a systolic contraction. A normal adult LVEF is roughly 55-70%. A low LVEF implies poor contractile function… which got people concerned.
Fast forward to my cardiothoracic anesthesiology fellowship. Most patients had some degree of impaired LVEF with related valvular pathologies, diastolic dysfunction, etc. Although appropriate planning was necessary, I tried not to fixate on low LVEF, and instead, considered overall cardiac output (flow).
Cardiac output is the product of heart rate and stroke volume. Stroke volume, in turn, is determined by cardiac preload, contractility, and afterload. If a patient has a massively dilated left ventricular cavity, they may still have a decent stroke volume in the context of depressed LVEF. Why? Because a small percentage (low LVEF) of a large number (dilated LV cavity) might be comparable to a large percentage (high LVEF) of a normal number (normal LV cavity). Additionally, if their contractility can be augmented with inotropic support, then I feel reassured that I can recruit the heart to do more work if needed.
Now let’s look at a case:
Imagine doing a large thoracic operation in this patient where intraoperative transesophageal echocardiography (TEE) is contraindicated and massive fluid shifts are anticipated. How do we proceed?
Preoperatively, patients like this usually have a myriad of cardiac studies: echocardiography, EKG, catheterization, sometimes MRIs, etc. While these are useful in understanding the pathophysiology at play, what’s more important is the patient’s overall functional status. Are they walking around without shortness of breath or chest pain? Do they require any oxygen? Are they able to perform their activities of daily living (ADL) independently? These are often useful clues about how compensated the patient is, and if there are any areas to optimize prior to surgery.
These cases are also discussed at length between the anesthesiologist and surgeon – the surgical plan, what problems do we foresee, what kinds of monitors do we need (in this case, arterial line, central line, PA catheter, and cardiac output monitor), any special medications or therapies (vasopressors, inotropes, etc.), do we plan on remaining intubated after the surgery, etc.
Although these cases are challenging, as always, it’s important to have a team-based approach while keeping the patient’s best interests and safety in mind at all points!
Drop me a comment below with questions! 🙂
