Assessment of lower limb flow and adequate intra-arterial papaverine doses to achieve maximal hyperemia in elder subjects

Utility and optimal dose of nicorandil for physiological assessment of the femoropopliteal artery

BACKGROUND

Nicorandil is widely used as a vasodilator for the physiological assessment of coronary arteries because of its usefulness and safety; however, there are no data on its use in peripheral arteries.

AIMS

To identify the utility of nicorandil and its appropriate dose for the physiological assessment on the femoropopliteal artery.

METHODS

We retrospectively enrolled patients from three institutes in which physiological assessment was carried out with various doses of nicorandil before treatment. Twenty-four femoropopliteal artery stenotic lesions from 22 patients were included. The nicorandil doses used were 2, 4, and 6 mg. Twenty-two lesions were also assessed using 30 mg of papaverine. The pressure gradient (PG) and peripheral fractional flow reserve (pFFR) were calculated based on the mean and systolic pressure levels. We examined the correlation of each parameter with the peak systolic velocity ratio (PSVR) based on the duplex ultrasound images using Spearman's rank correlation coefficient. Systemic blood pressure was assessed for safety.

RESULTS

The correlations were higher for mean pressure-based parameters than for systolic pressure-based parameters. As the nicorandil dose increased, the correlations among PG, pFFR, and PSVR also increased (mean pressure-based PG: 2 mg, r = 0.360; 4 mg, r = 0.498; 6 mg, r = 0.694, mean pressure-based pFFR: 2 mg, r = -0.479; 4 mg, r = -0.469; 6 mg, r = -0.641). The blood pressure after the administration of 6 mg of nicorandil was low, and the median systemic mean pressure was 65 mmHg.

CONCLUSION

A 4 mg dose of nicorandil is effective and safe for the mean pressure-based physiological assessment of lesions in the femoropopliteal artery.

Pathophysiological Significance of Velocity-Based Microvascular Resistance at Maximal Hyperemia in Peripheral Artery Disease

AIM

Maximal hyperemic response, leading to examination of microvascular resistance in lower-limb lesions is not well understood. This study aimed to investigate the infrainguinal arterial physiological response through a hyperemic condition and the pathophysiological significance of microvascular resistance in peripheral artery disease.

METHODS

Sixteen limbs with focal stenosis of the superficial femoral artery (SFA) and 16 control limbs were analyzed. We assessed the fractional flow reserve (FFR), vascular flow reserve (VFR), and hyperemic microvascular resistance (h-MR) of the SFA with a pressure/Doppler flow sensor-tipped combination guidewire before and after endovascular therapy (EVT). Skin perfusion pressure (SPP) on both the dorsal and the plantar sides of the foot was measured at baseline before and after the endovascular procedures.

RESULTS

FFR (p＜0.05) and VFR (p＜0.05), but not h-MR, improved after EVT. There was no association between h-MR and FFR or VFR before EVT. h-MR was negatively correlated with the dorsal SPP before EVT (r=－0.589, p＜0.05). h-MR in patients with high h-MR before EVT significantly decreased after EVT (p＜0.05). Patients with high, but not those with low, h-MR before EVT exhibited a significant increase in dorsal and plantar SPP after EVT (p＜0.05, each).

CONCLUSION

EVT for SFA stenosis improved FFR and VFR comprehensively, with no apparent change in h-MR. However, high h-MR before EVT may play a predictive role for limb perfusion improvement associated with h-MR reduction after EVT.