Case Of the Week #4
Left femoral DVT and pulmonary embolism
with right heart strain
In this patient who presented to the hospital with palpitations, tachycardia and dyspnea on exertion after a trip to California, PE should be on the differential diagnosis. The resting heart rate above 100 in sinus rhythm should be concerning but is of course not specific to a pulmonary embolus. Other possible diagnoses could be pneumonia, pulmonary hypertension, pneumothorax, atypical angina due to coronary artery disease among others.
If you are looking for a pulmonary embolus, it is very important to know the limitations of POCUS, which is not very sensitive or specific in this case. A pulmonary embolus needs to be diagnosed indirectly and would need a confirmatory CT angiogram in cases which it is possible.
One study from 2017 compared typical assessment for (d-dimer and Wells score) vs d-dimer/Wells score + ultrasound exam looking for DVT and pulmonary infarcts. As expected, the ultrasound group performed better ( Sensitivity of 69% vs 57% and specificity of 88% vs 68%) but still not good enough to rely on ultrasound alone.
In this patient's anterior lung exam, you can see A-lines, or horizontal lines that are reflections of the pleural line. You may also appreciate that the pleural line has lung sliding and is smooth. This was consistent on both anterior lung fields. Go here to learn about the lung POCUS exam.
The posterior lung fields looked similar. A-line pattern. No evidence of spotlight projections (b-lines). There is lung sliding throughout, so unlikely to be a pneumothorax.
Thus far, we can rule out pulmonary edema. Pneumonia is less likely. Also heart failure is less likely without any evidence of pulmonary edema. In the first parasternal long view, it appears mostly normal, just some tachycardia. The right ventricle is enlarged but it is difficult to say for sure in this view.
The parasternal short axis view shows the D-sign consistent with right ventricular strain due to a pulmonary embolus. As you can see, the left ventricle is more of a D shape than a circle. This is called the "d-sign" or septal shift. In one study, it was 88% specific for pulmonary embolus, but expectedly not sensitive at all, as this is only seen with a larger pulmonary embolus.
With a d-sign present, we now suspect a pulmonary embolus especially with his recent flight from California. A lower extremity DVT exam reveals a left femoral DVT.
With compression of the ultrasound probe, the femoral vein does not completely collapse. For more on DVT exam, see our tutorial.
Now that you have a near certain diagnosis, it may be indicated to start anticoagulation before confirming on the CTA. If there is huge clot burden, or the patient is unstable, IR should be consulted for possible thrombolysis. Either way, the DVT must be treated. There are many references for how to treat DVT/PE, we prefer this one in CHEST.