7/17/2019 Ankle-brachial Index (ABI)

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Retinal emboli have particular cardiovascular impor-tance. Of these, platelet emboli are both the most com-mon and the most evanescent. Hollenhorst cholesterolplaques may be detected at the same bifurcations for months to years after the embolic shower. Platelet emboli,Hollenhorst plaques, and calcium emboli are usually seenalong the course of a retinal artery, and their presenceindicates that a patient is shedding from the heart, aorta,

great vessels, or carotid arteries.

EXAMINATION OF THE ABDOMEN

The diameter of the abdominal  aorta should be esti-mated. A pulsatile, expansible mass is indicative of anabdominal aortic aneurysm (Chap. 38). An abdominalaortic aneurysm may be missed if the examiner does notassess the area above the umbilicus.

Specific abnormalities of the abdomen may be sec-ondary to heart disease.A large, tender liver is commonin patients with heart failure or constrictive pericarditis.

Systolic hepatic pulsations are frequent in patients withtricuspid regurgitation.A palpable spleen is a late sign inpatients with severe heart failure and is also often evi-dent in patients with infective endocarditis. Ascites mayoccur with heart failure alone, but it is less commonwith the use of diuretic therapy. Constrictive pericarditisshould be considered when the ascites is out of propor-tion to peripheral edema. When there is an arteriove-nous fistula, a continuous murmur may be heard over the abdomen. A systolic bruit heard over the kidneyareas may signify renal artery stenosis in patients withsystemic hypertension.

EXAMINATION OF THE EXTREMITIES

Examination of the upper and lower extremities may pro-vide important diagnostic information. Palpation of theperipheral arterial pulses in the upper and lower extremi-ties is necessary to define the adequacy of systemic bloodflow and to detect the presence of occlusive arteriallesions.Atherosclerosis of the peripheral arteries may pro-duce intermittent claudication of the buttock, calf, thigh,or foot, with severe disease resulting in tissue damage of the toes. Peripheral atherosclerosis is an important risk

factor for coincident ischemic heart disease.The ankle-brachial index (ABI) is useful in cardiovas-

cular risk assessment.The ABI is the ratio of the systolicblood pressure at the ankle divided by the higher of thetwo arm systolic blood pressures. It reflects the degree of lower-extremity arterial occlusive disease, which is man-ifest by reduced blood pressure distal to stenotic lesions.Either posterior tibial or dorsalis pedis artery pressurescan be used. It is important to note that each equallyreflects the status of the aortoiliac and femoropoplitealsegments but different tibial arteries; therefore, the

resulting ABIs may differ. An arm systolic pressure of 120 mmHg and an ankle systolic pressure of 60 mmHg

 yields an ABI of 0.5 (60/120). The ABI is inverselyrelated to disease severity. A resting ABI <0.9 is consid-ered abnormal. Lower values correspond to progressivelymore severe occlusive peripheral arterial disease (PAD)and disabling claudication. An ABI <0.3 is consistentwith critical ischemia, rest pain, and tissue loss.

Thrombophlebitis often causes pain (in the calf or thigh) or edema, and when present, pulmonary embolishould be considered as well. Edema of the lower extrem-ities is a sign of heart failure but may also be secondary tolocal factors, such varicose veins or thrombophlebitis, or to the removal of veins at coronary artery bypass surgery.Under such circumstances, the edema is often unilateral.

 ARTERIAL PRESSURE PULSE

The normal central aortic pulse wave is characterized bya fairly rapid rise to a somewhat rounded peak (Fig. 9-1).

The anacrotic shoulder, present on the ascending limb,occurs at the time of peak rate of aortic flow just beforemaximum pressure is reached.The less-steep descendinglimb is interrupted by a sharp downward deflection,coincident with aortic valve closure, called the incisura.As the pulse wave is transmitted distally, the initial upstrokebecomes steeper, the anacrotic shoulder becomes lessapparent, and the smoother dicrotic notch replaces the

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AOP

ECG   ECG

Apex

ACG

CP

LSB

JVP

ES SC

A2

B A

P2S1S1   S2

E

S3

OSS4

a 

a c 

x 

v 

y     O

      R     F     W

FIGURE 9-1

 A. Schematic representation of electrocardiogram, aortic

pressure pulse (AOP), phonocardiogram recorded at the

apex, and apex cardiogram (ACG). On the phonocardiogram,

S1, S2, S3, and S4 represent the first through fourth heart

sounds; OS represents the opening snap of the mitral valve,

which occurs coincident with the O point of the apex cardio-

gram. S3 occurs coincident with the termination of the rapid-

filling wave (RFW) of the ACG, while S4 occurs coincident

with the  a wave of the ACG.  B. Simultaneous recording of

electrocardiogram, indirect carotid pulse (CP), phonocardio-

gram along the left sternal border (LSB), and indirect jugular

venous pulse (JVP). ES, ejection sound; SC, systolic click.