Diagnosis: Peripartum Cardiomyopathy (PPCM)
This patient presented with nonspecific symptoms of SOB/DOE that had been getting worse since she had a vaginal delivery. He chest X-ray showed pulmonary vascular congestion, so a bedside echocardiogram was performed. This parasternal long axis (PLAX) view of the heart demonstrates a mildly diminished left ventricular systolic ejection fraction consistent with congestive heart failure. There is no pericardial effusion and the LV is larger than the RV in the apical view.
While this echo isn’t as obvious as a patient with cardiogenic shock, it does demonstrate mild to moderate LV systolic failure. Remember that if you have a question about your gestalt feel for LV function, you can measure the EPSS to quantify what you see. The EPSS on this patient was measured to be 11.5 mm.
Peripartum Cardiomyopathy is a relatively rare condition, occurring in 1 in every 2289 live births. However, it should not be missed because it carries with it a 2% mortality risk along with significant morbidity.1 While most PPCM is diagnosed postpartum, 17% of patients present antepartum, so remember to keep PPCM in your differential in late third trimester patients with dyspnea.2
- The PLAX position is a fantastic view to estimate left ventricular systolic function, but it can be easy to misinterpret if proper technique is not used to obtain optimal images.
- The patient should lie in the left lateral decubitus position if able and the phased array probe should be held like a pencil with the probe marker toward the patient’s left hip (assuming left screen dot position).3
- The typical location for the PLAX window is 3-4 cm to the left of the sternum at the 4th-5th intercostal space. Of course, every patient is unique so the best window may be 1-3 rib spaces up or down. One common example is patients with COPD, whose PLAX window is typically quite caudal, near the lower sternal border or xyphoid process.
- The structure to look for initially is the mitral valve, and once it is identified you should apply enough pressure to optimize cardiac visualization (hard enough for the patient to say “ouch,” then back it off a little).
- The probe should then be manipulated so that the aortic and mitral valves can clearly be seen, and so that the that the LV lumen is visualized. Ideally the LV should be perpendicular to the axis of the ultrasound beam. It is not expected that the apex be visualized in this view. Here are four common mistakes when obtaining a PLAX view and how to correct them:
- In this echo we have a great view of the LV, but we are looking at the heart from close to the apex. Sometimes this is the only view obtainable, and while it isn’t ideal, you can still get a good gestalt of LV function. To correct: Reposition the probe closer to the sternum and cranially one to two rib spaces.
- This view of the heart makes the LV appear very short and circular, and the apparent LV ejection fraction is very high. This is typically the result of an over or under rotated probe, giving an oblique view of the LV. To correct, just twist the probe in each direction until you see the LV elongate and open up.
- This is an OK view of the LV at end-diastole, but as the heart contracts we lose sight of the LV lumen. This means that the ultrasound beam is not slicing through the middle of the LV, it is catching the lateral wall as it pulls in. To correct: fan side to side (left shoulder/right hip) until you can see the LV lumen through the entire cycle.
- In this echo, we have a great view of the mitral and aortic valves, as well as the left atrium. However, the LV is supposed to be the star of the show. To correct: tilt the probe toward the patient’s right shoulder and position the mitral valve at about 1/3 of the screen from the right.
- Mielniczuk LM, Williams K, Davis DR, et al. Frequency of peripartum cardiomyopathy. Am J Cardiol. 2006;97(12):1765-8. [pubmed]
- Ramaraj R, Sorrell VL. Peripartum cardiomyopathy: Causes, diagnosis, and treatment. Cleve Clin J Med. 2009;76(5):289-96. [PDF]
- Dawson, Mallin. Introduction to Bedside Ultrasound, Volume 1. 2013. Apple iBook. [iBook]