Direct Quantitative Assessment of the Peripheral Artery Collateral Circulation in Patients Undergoing Angiography
Background—Despite the fact that numerous studies pursued the strategy of improving collateral function in patients with peripheral artery disease (PAD), there is currently no method available to quantify collateral arterial function of the lower limb.
Methods and Results—Pressure-derived collateral flow index [CFIp=(Poccl-CVP)/(Pao-CVP); pressure values in mmHg)] of the left superficial femoral artery (SFA) was obtained in patients undergoing elective coronary angiography using a combined pressure/Doppler wire (n=30). Distal occlusive pressure (Poccl) and toe oxygen saturation (SaO2) were measured for 5 minutes (min) under resting conditions, followed by an exercise protocol (repetitive plantar-flexion movements in supine position, n=28). In all patients, balloon occlusion of the SFA over 5 min was painless under resting conditions. CFIp increased during the first 3 min from 0.451±0.168 to 0.551±0.172 (P=0.0003), while SaO2 decreased from 98±2% to 93±7% (P=0.004). Maximal changes of SaO2 were inversely related to maximal CFIp (r2=0.33, P=0.003). During exercise, CFIp dropped within 1 min from 0.560±0.178 to 0.393±0.168 (P<0.0001) and reached its minimum after 2 min of exercise (0.347±0.176) while SaO2 declined to a minimum of 86±6% (P=0.002). Twenty-five patients (89%) experienced pain or cramps/tired muscles, while 3 (11%) remained symptom-free for an occlusion time of 10 min. CFIp values were positively related to the pain-free time span (r2=0.50, P=0.002).
Conclusions—Quantitatively assessed collateral arterial function at rest determined in the non-stenotic SFA is sufficient to prevent ischemic symptoms during a total occlusion of 5 minutes. During exercise, there is a decline in CFIp indicating a supply-demand mismatch via collaterals or — alternatively — a steal phenomenon.
Clinical Trial Registration Information—clinicaltrials.gov. Identifier: NCT01742455.
- balloon occlusion
- exercise physiology
- collateral circulation
- peripheral vasculature
- peripheral artery disease
- Received December 8, 2012.
- Revision received June 17, 2013.
- Accepted June 24, 2013.