Coronary flow reserve in adults with systemic right or single ventricles
Journal of Cardiovascular Magnetic Resonance volume 18, Article number: P173 (2016)
Late failure of systemic right and single ventricles is difficult to predict. Approximately 1/3 of subjects with congenitally corrected transposition of the great arteries (ccTGA) have congestive heart failure by the fifth decade and 2/3 of subjects with ccTGA and significant associated defects have congestive heart failure by the age of 45 years. Perfusion defects have been identified at rest in 55 % of subjects with systemic right ventricles by dipyridamole sestamibi and with exercise in 45 %, which are not due to endovascular obstructive coronary disease. Subjects with perfusion defects typically have worse right ventricular function, but not always. It may be tied to coronary flow reserve and coronary mismatch in these hypertrophied ventricles. The objective of this study was to assess the technical feasibility of stress perfusion imaging by CMR and calculate coronary flow reserve in adults with systemic right or single ventricles.
With IRB approval and informed consent, 14 adult patients with either a systemic right ventricle or a single ventricle underwent CMR with vasodilator stress perfusion imaging using adenosine (140 mcg/kg/min). Data collection included stress perfusion imaging, measurement of cardiac volume metrics and rest perfusion imaging at least 20 minutes after adenosine. Global myocardial blood flow (MBF) in ml/min/g and coronary flow reserve (CFR) were quantified using a fully quantitative model constrained deconvolution. Subjects underwent additional data collection, including lab work, 6-minute walk test and ECG.
Table 1 summarizes patient characteristics and salient testing results. Two of 14 perfusion studies were not quanitifiable; one due to an incomplete first pass of contrast likely related to low EF, one had technical issues during imaging. Of the remaining 12 subjects, 10 had a measureable change in myocardial blood flow, and 2 did not. Stress measurements of myocardial blood flow were lower in most patients than established MBF values in normal ventricles. Figure 1 demonstrates the global myocardial blood flow at rest and during stress of a patient with high CFR.
Myocardial blood flow and coronary flow reserve are quantifiable with current techniques regardless of ventricular morphology. This technique shows promise as a potential method of risk stratification of this population.
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Olivieri, L., Hsu, LY., John, A. et al. Coronary flow reserve in adults with systemic right or single ventricles. J Cardiovasc Magn Reson 18 (Suppl 1), P173 (2016). https://doi.org/10.1186/1532-429X-18-S1-P173