Assessment of coronary flow reserve by coronary pressure measurement: comparison with flow- or velocity-derived coronary flow reserve.

OBJECTIVES: This study sought to assess the reliability of pressure-derived coronary flow reserve (CFR) compared with flow- or velocity-derived CFR. BACKGROUND: Coronary flow reserve has been reported to have important clinical implications for the evaluation and treatment of coronary artery disease. METHODS: Using a pressure guide wire, coronary pressure distal to the stenosis was measured at rest and during hyperemia in seven dogs with various degrees of stenosis and in 30 patients with angina (29 and 34 stenoses in total, respectively). Pressure at the tip of the guiding catheter was also recorded with a fluid-filled transducer system. Pressure-derived CFR was calculated by the square root of the pressure gradient across the stenosis (DeltaP) during hyperemia divided by DeltaP at rest, using a proprietary software system. At the same time, coronary flow was monitored proximal to the stenosis with a flow meter in the experimental dogs, and coronary flow velocity distal to the stenosis was assessed using a Doppler guide wire in patients with angina. Flow-derived (or velocity-derived) CFR was compared with pressure-derived CFR. RESULTS: Except for one stenosis that showed no DeltaP at rest, a significant correlation was obtained between pressure- and flow-derived CFR in the animal study (y = 1.05x - 0.03, r = 0.92, p = 0.0001). A significant correlation was also seen between pressure- and velocity-derived CFR in the human study, except in three stenoses with no resting DeltaP (y = 0.70x + 0.37, r = 0.85, p = 0.0001). CONCLUSIONS: Similar to flow (or velocity) measurement, CFR can be assessed by pressure measurement, except in stenoses with minor resting DeltaP.

Noninvasive assessment of great cardiac vein flow by Doppler echocardiography: a validation study.

The objectives of this study were (1) to compare great cardiac vein (GCV) flow velocity detected by pulsed Doppler echocardiography (PDE) with Doppler guide wire (DGW) in the experimental setting and (2) to clarify whether transthoracic Doppler echocardiography (TTDE) can detect GCV flow in humans. Using opened-chest dogs, we detected GCV flow by PDE under the guidance of color flow Doppler mapping. GCV flow velocity was recorded by PDE and DGW, simultaneously. In 23 volunteers, GCV flow velocity was measured by TTDE. In the experimental setting, the prominent systolic flow wave of the GCV was obtained in PDE and DGW. There were good agreements between PDE and DGW for the measurements of GCV flow velocity (peak velocity: r = 0.98, y = 1.12chi-5.9; time velocity integral: r = 0.97, y = 1.10chi-0.71). In the human subjects, clear envelopes of GCV flow velocity were obtained in 21 (91%) of 23 subjects with the use of TTDE.

Decreased left atrial appendage flow velocity with atrial fibrillation caused by negative inotropic agents: report of two cases.

Although pharmacological agents are frequently used to control ventricular rate or restore sinus rhythm of patients with atrial fibrillation (AF), there are no reports of the relationship between those agents and left atrial appendage (LAA) function. Two cases of a decrease in LAA blood flow velocity caused by negative inotropic agents are presented as an indication that negative inotropic agents are a risk factor for systemic thromboembolism with AF.

[Measurement of coronary flow reserve by pressure/temperature sensor guide wire-based thermodilution in experimental models].

OBJECTIVES: Recently, a combined 0.014 pressure/temperature sensor-mounted guide wire has been developed to simultaneously measure fractional flow reserve and coronary flow reserve (CFR) by thermodilution (CFR-thermo). The accuracy of CFR-thermo was compared with CFR obtained by flow rate (CFR-flow) in experimental models. METHODS: Using an experimental model made from a straight-rigid tube (4 mm diameter) filled with 36 degrees C water, CFR-thermo and CFR-flow were measured under different conditions of sensor position and injected water temperature (0-40 degrees C). A side branch (2 mm diameter) was then placed at 4, 6, 8 and 10 cm from the injected site just proximal to the stenosis. The degree of stenosis ranged from 0 to 75% (0%, 25%, 50%, 75%). CFR-thermo and CFR-flow were calculated from the inverse ratio of the mean transit time and the flow ratio during high flow to low flow rates. RESULTS: Under the conditions without the side branch, there were good correlations between CFR-thermo and CFR-flow if the temperature of the injected water was under 28 degrees C and the sensor was not placed within 4 cm from the injection site. With the side branch, CFR-thermo was smaller than CFR-flow although there were good correlations between CFR-thermo and CFR-flow. The value of CFR-thermo increased with more distal positions of the side branch to the injected site. CONCLUSIONS: Temperature of the injected water, and the position of the sensor, the side branch and the stenotic lesion may influence measurements of CFR-thermo. These effects should be considered when CFR is measured by the thermodilution method.