Consistency or Accuracy

I am currently working towards a career in echocardiography. This translates into ultrasounds done on the heart for functional and anatomic evaluation. In an exam patients have their hearts checked from different “views” or “slices” to determine whether the heart is functioning normally or if there is pathology that may require intervention or monitoring. There are many aspects to the exam which evaluate heart function but the area I am going to concentrate on here is the measurements done in the Parasternal Long Axis (PLAX) of the Aorta (Ao) and Left Ventricle (LV). One of the big things with taking any measurement is to try to be as accurate as possible. The diameter of the components of the A0 are used to assess whether there may be an underlying issue. The current accepted timing is based on the EKG readout as opposed to the timing in the heart cycle mechanically which will demonstrate the widest diameter. The majority of the measurements are indicated to be done at end diastole, which is about on the QRS interval but this may not be the optimal timing to measure in every patient as there is a delay between what happens electrically and what happens mechanically in the heart. The most representative measurements for this example are the Sinus of Valsalva, Sinotubular junction, and Ascending aorta.

The sonographer waits to get a representative image and freezes it. They can then pan back through a few heart cycles and use digital calipers to take measurements. Currently the methodology is to follow the events on the EKG as opposed to following the mechanical events happening visually on the screen. This is because of a desire for measurements to be taken more consistently between sonographers.

I realize the above may sound overly complicated but suffice to say that there are measurements of clinical importance which are currently being measured at a timing on an EKG for the sake of consistency between sonographers which provides a number which may be slightly below what would be measured at the widest aspect moments later. This isn’t to say that this would be causing harm to patients. When a number is out of normal range and clinically significant it is uncommon for it to go from you’re fine to needing intervention based on a small variation from the normal range. My issue with this is rather that the echocardiographers and the medical doctors reading the echos are highly trained in how to take these measurements and it should not be difficult to ask them to measure at the largest diameter which should be on or slightly after the QRS interval on the EKG.

The widest point of measurement will be able to be recognized visually by seeing what is happening with the valves of the heart. The EKG can be beneficial but it is not required to take representative measurements. The process should instead trust the training of the sonographer and the medical doctor to know when the most appropriate timing is to measure and instead indicate that it should be near the QRS, not mandate that the measurements be taken on the QRS for every patient.