Author + information
- Curt DeGroff, MD⁎ ()
- ↵⁎Children’s Hospital, The University of Pittsburgh, The Heart Center, 3705 Fifth Avenue, Pittsburgh, Pennsylvania 15213
We read with interest the study published recently in the Journalby Tan et al. (1). We have several concerns.
First, the investigators point out in the Limitations section that the modified Bernoulli equation was not used in their study. However, Tan and colleagues do not give a justifiable reason for this in the cases studied. Did all these patients have a pre-coarctation velocity (i.e., V1) that was <1 m/s? Our concern is that this approach may mislead clinicians. Giving only a brief passing mention for the necessity for the modified Bernoulli equation in the Limitations section is troubling and may lead to misconceptions in the way this lesion is assessed in the cardiology community.
Second, and more important, the researchers mention that the peak systolic pressure gradient (SPG) is dependent on aortic compliance, and they reference a study by Tacy et al. (2). However, there is no mention that the measurement they propose clinicians use (diastolic velocity [DV]) may also be related to compliance as well. Experiments performed by Tacy et al. (2) and in our laboratory (3) suggest that diastolic runoff, and thus DV, depend on vessel compliance. To understand this point one simply has to take the argument to the extremes. If the entire aorta is noncompliant then there can be no diastolic runoff, even considering the most severe coarctation lesion. Of course, such a condition for the entire aorta is unlikely to exist, but it is useful to consider to demonstrate the concept of the relationship between diastolic runoff and aortic compliance. Taking several steps back from this extreme, if one considers the complexities to flow that occur with a stiff stent in place after intervention, it is clear that significantly more investigations are needed before such parameters as DV are freely used in clinical practice.
- American College of Cardiology Foundation