Simultaneous intracoronary velocity- and pressure-derived assessment of adenosine-induced collateral hemodynamics in patients with one- to two-vessel coronary artery disease
Christian Seiler, MD, FACCa,
Martin Fleisch, MDa,
Michael Billinger, MDa and
Bernhard Meier, MD, FACCa
a Division of Cardiology, University Hospital, Swiss Cardiovascular Center Bern, Bern, Switzerland
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Figure 1 Diagram showing two coronary arteries with interconnecting collaterals (depicted as one anastomosis). The stenotic lesion on the left side is occluded by an angioplasty balloon. Angioplasty guidewire-based Doppler- and pressure-sensors are positioned distal to the occluded stenosis in order to measure simultaneously occlusive i.c. velocity (i.e., velocity time integral, Vioccl, cm) and pressure (Poccl, mm Hg). At the same time, Pao is determined via the angioplasty guide catheter. A pressure- and velocity-derived collateral flow index (CFIp, mm Hg/mm Hg; CFIv, cm/cm) can be calculated as shown on the right side by additional measurement of the distal i.c. velocity during vessel patency (Viø-occl, cm; CVP = 5 mm Hg). The vascular resistance indexes of the collateral circulation (Rcoll, mm Hg/cm) and of the collateral-receiving (i.e., ipsilateral) microcirculation (R4) can be computed. Resistance indexes of the contralateral side (R1 and R3) cannot be determined. CFIp = pressure-derived collateral flow index; CFIv = velocity-derived collateral flow index; CVP = central venous pressure; i.c. = intracoronary; Pao = mean aortic pressure; Poccl = distal coronary occlusive pressure; Rcoll = collateral resistance index; R1 = epicardial vascular resistance; R3 = contralateral resistance index; R4 = ipsilateral resistance index; Vioccl = distal velocity time integral during vessel occlusion; Viø-occl = distal velocity time integral during vessel patency.
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Figure 2 Simultaneous determination of i.c. distal occlusive velocity (Vioccl = 2.5 cm; upper panel, left side) and wedge pressure (Poccl = 10 mm Hg) together with mean aortic pressure (Pao = 94 mm Hg; right side). The i.c. flow velocity tracing during vessel patency (Viø-occl = 48 cm), i.e., after dilation of the stenosis and following cessation of hyperemia, is shown on the lower left hand side. The flow velocity tracings depict the instantaneous velocity over time (horizontal axis) in the upper, and the flow velocity trend over 90 s in the lower part of the panels. The trend of the lower panel gives also the coronary flow velocity reserve (CFVR, "ratio" = 2.1) measurement. Velocity-derived collateral flow index (CFIv) in this example is equal to 2.5/48 = 0.05. During coronary occlusion, the i.c. ECG shows ST-elevations (right side panel) which disappear after PTCA balloon deflation. APV = average peak flow velocity (cm/s, i.e. maximum flow velocity during a cardiac cycle averaged over three cardiac cycles); B = baseline flow velocity (cm/s) at rest; CFVR = coronary flow velocity reserve; Pra = right atrial or central venous pressure (CVP); P = peak flow velocity during hyperemia; PTCA = percutaneous transluminal coronary angioplasty; S = search mode for peak flow velocity.
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Figure 3 Individual, collateral flow index values (CFIp, vertical axis, left side panel) at baseline and during adenosine infusion (top panel, horizontal axis). The triangles indicate mean values (± standard deviation). The bottom panel depicts individual, absolute CFIp changes in response to adenosine (i.e. CFIp during hyperemia – CFIp at rest). They were significantly lower in patients with angiographic collateral degree <2 than in those with  2 (horizontal axis). CFIp = pressure derived collateral flow index.
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Figure 4 Correlations between the structural (% diameter stenosis, n = 50; horizontal axis; top panel) and the functional (distal coronary flow velocity reserve, n = 12; horizontal axis; bottom panel) stenosis severity of the contralateral coronary artery and the adenosine-induced collateral flow index change (delta CFIp, vertical axis). The regression equations provided describe the mentioned relations in patients with good collaterals. There were no respective associations in patients with poor collaterals. Closed symbols: patients with good collaterals (angiographic degree 2); crossed symbols: patients with poor collaterals (degree <2).
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