## Coronary Artery Z-Score Calculator

Coronary Artery Involvement in Children With Kawasaki Disease, just published in this month's Circulation, contains a Z-Score gem: updated prediction equations for coronary arteries. These new prediction equations provide one major advantage over the equations of de Zorzi et al.: they account for the tendency towards non-constant variance, i.e. heteroscedasticity. It is interesting to note that, based on prior work in 2005, one might have expected the prediction equations to be linear regressions based upon the square root of body surface area (BSA raised to the 0.5 power). Instead, the prediction equations are nonlinear and relate to the BSA raised to the 0.3xxx power...
Perhaps the coronary artery system is different enough in structure and function that it does not obey the same rules for parent/daughter vessels in the remainder of the arterial tree. On a more practical note, the authors excluded the left main coronary artery from their analysis, noting:

normal anatomic variations make its interpretation less reliable

The normal variation of the coronary arteries includes such arrangements as left-dominant and right-dominant systems, long and short main coronary artery segments, and even separate origins of the circumflex and anterior descending coronary arteries, to the exclusion of the left main altogether. I doubt that this point gives us a hall pass to abandon measuring the left main coronary artery in our Kawasaki patients, but it is certainly an important observation.

Check out the new and improved Kawasaki Disease Coronary Artery Z-Score calculator here:

## How To Image Patients With Dextrocardia

Based upon: ASE Sonographer Core Curriculum Understanding the cardinal directions that are expected in each of the imaging planes will greatly simplify the sonographer's work when evaluating patients with complex congenital heart disease- particularly those patients with dextrocardia. Dextrocardia: heart is positioned in the right chest, apex pointing rightward (as opposed to Dextroposition: heart is positioned in the right chest, apex pointing leftward {or toward midline})

Parasternal Long Axis:

• "base" on the right side of screen
• apex of heart on left side of screen
• image is then an anterior-posterior section along the cardiac long axis- regardless of cardiac position
• if patient has dextrocardia, image should be labeled "DEXTRO" or "RSB" (for Right Sternal Border)
Parasternal Short Axis:
• 90 degrees CLOCKWISE from long axis
• patient left is on right side of screen
Apical 4-Chamber:
• patient left is on right side of screen
Subcostal Transverse:
• patient left is on right side of screen
Subcostal Short Axis:
• 90 degrees CLOCKWISE from transverse
Suprasternal Notch Short Axis:
• patient left is on right side of screen
Suprasternal Notch Long Axis:
• ascending aorta on left side of screen, descending aorta on right (regardless of laterality)
When confronted with a patient with known (or suspected) cardiac malposition, begin scanning from the subcostal transverse imaging plane. The transducer index mark and image (screen) index mark should both be oriented to the patient's LEFT:
• subcostal transverse: define absolute and relative positions of AO, IVC, and spine
• sweep (tilt) up to demonstrate the position of the heart in the chest and the direction the apex is pointing
• sweep (continue tilting) anterior to determine the AV and VA connections and positions of the great vessels
Allow yourself a few minutes at the outset of the exam to determine the cardiac position, situs, AV/VA connections- before recording an echo "officially". It is far easier to record an echo, adhering to the imaging protocol, when you already know what to expect (because you spent the time to figure it out). Lastly, it is worth mentioning that positioning- of both the patient and the sonographer- can impact the performance of the exam. Patients with dextrocardia should be optimally positioned in the right lateral decubitus position, and the sonographer should be positioned such that scanning can be comfortably performed with the patient in that position.