Measurement of regional myocardial perfusion and mass by subselective hydrogen infusion and washout techniques: a validation study.

A technique was developed for measuring regional myocardial perfusion by intracoronary infusions of hydrogen (H2)-saturated saline. H2 concentration was detected during washout in the pulmonary artery by means of the voltage response of a platinum-tipped electrode. Regional myocardial perfusion was calculated from the H2 exponential desaturation curve according to the Kety-Schmidt principle. In 16 anesthetized open-chest dogs, validation of this technique was performed at baseline, reduced (stenosis), and hyperemic (dipyridamole) flow states by means of the radionuclide-labeled microsphere reference withdrawal technique. There was an excellent quadratic correlation between microsphere and H2 washout techniques (range 0.11 to 3.15 ml/min/g) (n = 33, r = .92, y = -0.12x2 + 0.89x + 0.20, SEE = 0.20 ml/min/g; p less than .0001). Hyperemic regional myocardial perfusion was underestimated by H2 washout and severely ischemic regional myocardial perfusion was overestimated. When regional myocardial perfusion values greater than twice normal were excluded, a strong linear correlation was present between H2 and microsphere measurements (n = 27, r = .89, y = 0.76x + 0.22, SEE = 0.18 ml/min/g; p less than .0001). The H2 washout method was further tested in 18 additional open chest dogs for calculations of the mass of an arterial perfusion bed according to the principle that the mass of the bed (g) equals coronary blood flow (ml/min) divided by regional myocardial perfusion (ml/min/g).(ABSTRACT TRUNCATED AT 250 WORDS)