Continuous regional myocardial blood flow measurement: validation of a near-infrared laser Doppler device in a porcine model.

OBJECTIVE: RMBF measurement is a major concern in various clinical and experimental settings, but no validated device for RMBF is currently available. METHODS: An LVP-triggered laser Doppler to measure RMBF was validated by simultaneous fluorescent MS RMBF in a porcine LAD flow reduction model (n = 10 pigs). The laser probe was positioned on the left ventricle's anterior wall. LAD blood flow reduction was achieved by a shaft-driven occluder positioned proximal to the transit-time flow meter measuring coronary blood flow. RMBF was measured at baseline; after the reduction of LAD blood flow to 70% and 30% of baseline; at 20 and 120 minutes of reperfusion; and, finally, 15 minutes after LAD occlusion. RESULTS: Laser Doppler RMBF (LDU) correlated strongly with MS RMBF under all tested conditions: baseline (epicardial 194.7 ± 41.9, endocardial 130.2 ± 29.2); 70% baseline-flow (epicardial 160.4 ± 27.7, endocardial 112.1 ± 15.1); 30% baseline-flow (epicardial 44.3 ± 5.5, endocardial 32.9 ± 9); 20 minutes reperfusion (epicardial 175.8 ± 33.6, endocardial 126.5 ± 30); 120 minutes reperfusion (epicardial 146.3 ± 31.1, endocardial 107.1 ± 29.7); and complete LAD occlusion (epicardial 10.5 ± 5.8 endocardial 1.4 ± 0.3) (r = 0.986-0.962, p < 0.001). CONCLUSIONS: This new blood pressure waveform-triggered laser Doppler probe is able to measure RMBF at different depths online in the beating heart.

Palmar microcirculation after harvesting of the radial artery in coronary revascularization.

PURPOSE: To evaluate real-time parameters of palmar microcirculation before and after harvesting of the radial artery in coronary revascularization using a laser Doppler flowmetry and remission spectroscopy system (O2C). DESCRIPTION: Fifteen patients (11 males, 54 +/- 4 years, mean New York Heart Association [NYHA] class of 2.3 +/- 0.3) were prospectively scheduled with control measurements of the fingertips of D1, D3, and D5 at base line, after suprasystolic, and after selective radial or ulnar compression for tissue oxygen saturation (SO2), postcapillary venous recombinant hemoglobin (rHb) concentration, superficial (2 mm) blood flow, and deep (8 mm) blood flow. EVALUATION: Preoperatively during suprasystolic compression SO2 decreased significantly for the fingertips of D1, D3, and D5 by -58%, -74%, and -63%, respectively (p < 0.05). Radial compression reduced SO2 for all fingertips (-12%, -14%, and -16%), as did ulnar compression (-24%, -18%, and -10%). rHb did not change significantly for either compression type. Superficial and deep blood flow decreased significantly after suprasystolic and only slightly after radial and ulnar compression at either side. No side differences were noted. After radial artery harvesting, microcirculatory parameters did not change considerably versus preoperatively. CONCLUSIONS: Radial artery harvesting does not remarkably change microcirculatory parameters of the hand. The O2C system is a safe and quantitative method to assess both preoperatively and postoperatively the palmar microcirculation and therefore adds further functional clinical information.

A remission spectroscopy system for in vivo monitoring of hemoglobin oxygen saturation in murine hepatic sinusoids, in early systemic inflammation.

BACKGROUND: During the early stages of systemic inflammation, the liver integrity is compromised by microcirculatory disturbances and subsequent hepatocellular injury. Little is known about the relationship between the hemoglobin oxygen saturation (HbsO2) in sinusoids and the hepatocellular mitochondrial redox state, in early systemic inflammation. In a murine model of early systemic inflammation, we have explored the association between the sinusoidal HbsO2 detected with a remission spectroscopy system and 1.) the NAD(P)H autofluorescence (an indicator of the intracellular mitochondrial redox state) and 2.) the markers of hepatocellular injury. RESULTS: Animals submitted to 1 hour bilateral hindlimb ischemia (I) and 3 hours of reperfusion (R) (3.0 h I/R) exhibited lower HbsO2 values when compared with sham. Six hours I/R (1 hour bilateral hindlimb ischemia and 6 hours of reperfusion) and the continuous infusion of endothelin-1 (ET-1) further aggravated the hypoxia in HbsO2. The detected NAD(P)H autofluorescence correlated with the detected HbsO2 values and showed the same developing. Three hours I/R resulted in elevated NAD(P)H autofluorescence compared with sham animals. Animals after 6.0 h I/R and continuous infusion of ET-1 revealed higher NAD(P)H autofluorescence compared with 3.0 h I/R animals. Overall the analysed HbsO2 values correlated with all markers of hepatocellular injury. CONCLUSION: During the early stages of systemic inflammation, there is a significant decrease in hepatic sinusoidal HbsO2. In parallel, we detected an increasing NAD(P)H autofluorescence representing an intracellular inadequate oxygen supply. Both changes are accompanied by increasing markers of liver cell injury. Therefore, remission spectroscopy in combination with NAD(P)H autofluorescence provides information on the oxygen distribution, the metabolic state and the mitochondrial redox potential, within the mouse liver.