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Cardio Diabetes Medicine 2017 89

Toe pressure measurement is a useful clinical meth- CT ANGIOGRAPHY
od especially in diabetics because digital vessels are CT Angiography has revolutionized the evaluation
usually spared from medial sclerosis. It is useful in and management of PAD. Current multidetector CTA
detecting individual at high risk of gangrene ulcer- scanners can generate high-resolution arterial imag-
ation and infection associated with PAD. Arterial BP es which allows superb delineation of small vessels
at toe is approximately 60% systolic BP at ankle. Toe in the foot. The volumetric acquisition of axial im-
systolic pressure index > 0.6 is a good screening test ages and software-based reformatting allows one
next to ABI.
to visualize the anatomy from multiple angles and
in multiple planes after a single acquisition. It has
SEGMENTAL ARTERIAL PRESSURE a sensitivity and specificity of greater than 95% for
Segmental limb pressure evaluation can help to identifying lesions greater than 50%, however limita-
identify the anatomic location and severity of lower tions are exposure to radiation and usage of 100 to
extremity PAD by comparing systolic blood pressure 150 ml of iodinated contrast. Extensive calcification
measurements at the upper and lower thigh, calf and can obscure the lumen and overestimate the degree
ankles. The difference in pressures between two ad- of stenosis
jacent leg segments, and between the two extremi-
ties at the same level is typically less than 20 mm/ Magnetic resonance angiography
hg. A pressure drop greater than 20 mm/hg implies Magnetic Resonance angiography (MRA) provides
the presence of an obstructive lesion between two excellent-quality image of the peripheral vascular
measured segments. system. Gadolinium-enhanced 3D MRA affords the
opportunity to acquire angiography like images. Con-
PULSE VOLUME RECORDING trast enhanced 3D MRA has a sensitivity of 95% and
The Pulse volume recording (PVR) is a form of air specificity of 97% for identifying PAD. Limitations of
plethysmography. A blood pressure cuff is placed on MRI are claustrophobia and inability to perform the
the lower extremity and inflated to a baseline pressure test in patients with intracranial artrial aneurysmal
of appropriately 65 mm/hg. Placement of the cuffs clips, and implantable devices like pacemakers, de-
is similar to those used for segmental pressures and fibrillators and pumps. Exposure to gadolinium-based
the cuff is attached to plethysmograph. The lower ex- contrast agent in the setting of renal failure has been
tremity pulsatile flow causes small changes in limb associated with nephrogenic systemic fibrosis, a rare
volume, which are recorded as arterial contours and dermopathy that involves fibrosis of the joints eyes,
correspond to direct arterial pressure waves record- and internal organs. Hence GFR < 30 ml/mt/1.73 me-
ed at that level. The normal PVR tracing has a sharp ter square is a contraindication for gadolinium en-
upstroke a distinct pulse peak, and a rapid decline. hanced MRA.
With increasing arterial obstruction the PVR tracing
becomes progressively flattened and prolonged. In MANAGEMENT OF PAD
patients with noncompressible vessels, the PVR is The overall treatment approach in the PAD patient
more reliable than segmental pressure or ABI.
focuses on 1) reducing cardiovascular events through
risk factor optimization, 2) preventing progression
DUPLEX ULTRASONOGRAPHY of PAD and limb loss, and 3) improving symptoms
Duplex Ultrasonography combines B-mode imaging and well-being through exercise regimen programes,
and pulse wave Doppler imaging. It is an accurate, pharmacotherapy and surgical / endovascular inter-
cost-effective non-invasive method to localize ste- ventions when required. Table.1.
nosis and differentiate stenosis from occlusion. Gray
scale B-mode imaging creates a 2-dimensional im- MEDICAL MANAGEMENT OF PAD
age of the arterial wall and lumen, which allows the PAD is associated with a high prevalence of cardio-
operator to identify morphological changes in the ar- vascular morbidity and mortality and is thus consid-
tery. Pulsed wave Doppler allows an estimation of the ered as a CHD risk equivalent by cholesterol guide-
degree of stenosis based on the blood flow velocity. lines. Hence all patients require aggressive manage-
In peripheral arteries a peak systolic velocity greater ment to optimize their CHD risk factors.
than 200 cm/sec correlates with an obstruction of
more than 50%. This test however is time consuming
and operator dependent.

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