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Nonsurgical restoration of pulsatile arterial flow.

Percutaneous transluminal angioplasty is an established method of revascularization in a variety of arterial stenotic conditions. When applied to specific morphologic and clinical indications, it can be very effective. It appears to be the procedure of choice for focal stenotic lesions of the iliac and femoropopliteal system. Its role in infrapopliteal atherosclerotic disease is less certain, but more optimistic, with recent reports. New methods for preventing restenosis and abrupt closure are currently being developed, and they appear to be promising as adjunctive therapy with mechanical catheter-directed intervention. The future of these adjunctive agents will likely improve the outcome and reduce the immediate failure rates of angioplasty. Other modalities, including thermal laser angioplasty and atherectomy, also appear to have a promising future. These methods, coupled with better endoluminal guidance, such as ultrasound, will help guide the interventional procedure more precisely and hopefully broaden the application and improve the outcome.

Angiography↗

[Effect of localized heat on blood flow in arteries of distribution].

In large arteries distributing blood to an area (hind leg of dog), local heat induces a vasodilatation. The mechanical reactions (variations of mean velocity of flow and amplitude of pulsatile flow) express a distal dilatation. Radial expansion responds in original way (pulsation become uniform).

Animals↗

Rationale of filtration enhancement in membrane plasmapheresis by pulsatile blood flow.

It has been demonstrated in our laboratory that blood flow pulsations enhance plasma filtration rate by 30-60 per cent. The increase in plasmafiltration over the steady flow value is found to be a function of the parameter F. delta V'/QB where F denotes the pulsation frequency, delta V' the volume amplitude of pulsed blood in the filter and QB is the time mean blood flow. The increment in plasma filtration may be related to the increase in time-mean absolute value of shear rate.

Animals↗

Flow in elliptical vessels calculated for a physiological waveform.

Understanding the nature of pulsatile flow is an important issue in haemodynamics, especially the initiation and progression of vascular disease. The geometry of a non-circular vessel was idealised to an elliptical cross-section, and the dynamic properties of the flow were calculated for a physiological waveform. The Fourier harmonics for a common carotid waveform were determined, and the velocity profile and wall shear stress were calculated from the superposition of the individual contributions from each harmonic. The effects of ellipticity on the flow pattern were found to be significant. The velocity profile along the major axis of the elliptical cross-section developed a flattened peak, which widened as the vessel became more elliptical. Wall shear stress demonstrated an angular dependence in elliptical vessels, where the point of minimum shear stress was located at the end of the major axis. Comparison with a cylindrical vessel demonstrated a 3% decrease in peak wall shear stress (tau = 2.96, N.m(-2)) at the end of the major axis, and 10% in the mean wall shear stress (tau = 0.44 N. m(-2)), for an elliptical vessel (epsilon = 0.8). The temporal average wall shear stress, which has been associated with atherogenic sites, also displayed a minimum at the end of the major axis that decreased with more elliptical cross-sections.

Blood Flow Velocity↗