1. Your patient is POD#0 s/p repair of Tetralogy of Fallot and now has developed a narrow complex tachycardia to 200 bpm with no clear p waves preceding the QRS on ECG monitoring. What might you see on the CVP waveform to support your suspected diagnosis?
a) loss of "a" waves
b) exaggerated "x" descent
c) cannon a waves
d) no y descent
2. How does milrinone affect the end diastolic pressure volume (EDPV) curve?
a) Shifts it to the right
b) Shifts it to the left
c) No effect
d) Depends on the effect it has on contractility
ANSWERS & EXPLANATIONS
1. C. The patient described most likely has junctional ectopic tachycaria (JET), which commonly occurs after congenital heart repairs. It presents as a narrow complex tachycardia with evidence of AV dissociation. Hence, the atria may contract against a closed tricuspid valve, leading to a prominent "a" wave known as a cannon "a" wave. Treatment for JET includes cooling, reducing inotropes as able, magnesium, and sometimes arrhythmic such as amiodarone.
2. A. Milrinone is a PDE3 inhibitor and has the unique property of increasing lusitropy, or diastolic function. Hence, it increases the compliance of the LV and thus would shift the EDPV curve to the right- for any given LV volume, there is less LV pressure given the increase in lusitropy and hence, ventricular compliance.