Scientific Publications Database

Article Title: Effects of Hypercapnia on Myocardial Blood Flow in Healthy Human Subjects
Authors: Pelletier-Galarneau, Matthieu; deKemp, Robert A.; Hunter, Chad R. R. N.; Klein, Ran; Klein, Michael; Ironstone, Joel; Fisher, Joseph A.; Ruddy, Terrence D.
Journal: JOURNAL OF NUCLEAR MEDICINE Volume 59 Issue 1
Date of Publication:2018
Abstract:
Elevation of the end-tidal partial pressure of CO2 (PETCO2) increases cerebral and myocardial blood flow (MBF), suggesting that it may be a suitable alternative to pharmacologic stress or exercise for myocardial perfusion imaging. The purpose of this study was to document the pharmacodynamics of CO2 for MBF using prospective end-tidal targeting to precisely control arterial P-CO2 and PET to measure the outcome variable, MBF. Methods: Ten healthy men underwent serial Rb-82 PET/CT imaging. Imaging was performed at rest and during 6-min hypercapnic plateaus (baseline; PETCO2 at 50, 55, and 60 mm Hg; repeat of PETCO2 at 60 mm Hg; and repeat of baseline). MBF was measured using 82Rb injected 3 min after the beginning of hypercapnia and a 1-tissue-compartment model with flow-dependent extraction correction. Results were compared with those obtained during an adenosine stress test (140 mu g/kg/min). Results: Baseline PETCO2 was 38.9 +/- 0.8 (mean 6 SD) mmHg (range, 35-43 mm Hg). All PETCO2 targets were sustained, with SDs of less than 1.5 mm Hg. Heart rate, systolic blood pressure, rate x pressure product, and respiratory frequency increased with progressive hypercapnia. MBF increased significantly at each level of hypercapnia to 1.92-fold over baseline (0.86 +/- 0.24 vs. 0.45 +/- 0.08 mL/min/g; P = 0.002) at a PETCO2 of 60 mm Hg. MBF after the administration of adenosine was significantly greater than that with the maximal hypercapnic stimulus (2.00 vs. 0.86 mL/min/g; P < 0.0001). Conclusion: To our knowledge, this study is the first to assess the response of MBF to different levels of hypercapnia in healthy humans with PET. MBF increased with increasing levels of hypercapnia; MBF at a PETCO2 of 60 mm Hg was double that at baseline.