Segmental Vascular Assessment
Level 1 Diagnostics’ Arterial Vascular Assessment measures blood pressure using the identical standard as conventional arm cuffs. While the traditional arm cuff method just measures blood pressure, our Arterial Vascular Assessment is a powerful measurement which provides further insight into arterial stiffness.
The information collected during the Arterial Vascular Assessment using the upper arm cuff is disseminated into a wide range of measurements. This data is then extrapolated into a number of indexes and further classifications which include the following:
• Ankle/Brachial Index (ABI)
• Toe/Brachial Index (TBI)
• Blood Pressure (Brachial, Ankle)
The information deduced from the Level 1 Diagnostics’ Arterial Vascular Assessment is invaluable for detecting risk factors and facilitating the identification of patients who may be at risk for cardiovascular events. Studies have shown that the Arterial Stiffness Index (ASI) illustrates a strong correlation between the functioning and integrity of coronary arteries and atherosclerotic lesions. This particular connection is significant in that atherosclerotic lesions are fatal yet may remain asymptomatic for decades. Over 60 million Americans carry these life-threatening issues so isolating high-risk individuals is very important.
Ankle-Brachial Index (ABI) Test
The ankle-brachial index (ABI) test is a quick and non-invasive assessment of the peripheral blood vessels to test for peripheral vascular disease. The ABI is the ratio of blood pressure in the brachial artery of the arm and in the lower legs. A large difference in the two pressures, signals peripheral artery disease (PAD).
PAD does not always cause symptoms. Many patients who have PAD don’t know it. They may even experience symptoms, such as pain, cramping or tingling in the legs, but often do not report it, believing it is a natural part of aging or caused by something else.
PAD develops when arteries become clogged with plaque (atherosclerosis) and limits the blood flow to the legs. Clogged arteries in the legs are a major risk factor for having a heart attack or stroke.
The American Heart Association reports that people with PAD have a four to five times greater risk of having a heart attack or stroke.
PVD results from atherosclerosis and inflammation and can then lead to stenosis, an embolism or thrombosis.
Peripheral vascular disease is more common in smokers and people with diabetes.
ABI score of 0.71 to .096 suggests the presence of mild ischemia.
ABI score of 0.31 to 0.7 indicates moderate ischemia with minimal symptoms such as intermittent claudication in the legs.
ABI score of 0.0 to 0.3 warns of severe ischemia with symptoms of ischemic pain in the legs while at rest.
Toe-Brachial Index (TBI) Assessment
The ankle – brachial pressure index (ABI) is a simple, useful method for diagnosing Peripheral Arterial Disease (PAD). In determining the severity of PAD in a lower extremity, the toe-brachial index (TBI) is used.
Due to both lifestyle and genetic reasons, arteries may become hardened. This atherosclerotic condition may not cause painful symptoms until the artery is narrowed 60% or more. A blood clot or piece of cholesterol or calcium that may break off and move into the artery could cause a blockage that would disrupt blood flow. The legs are the area of the body most commonly damaged by PAD.
Severe PAD may lead to Critical Limb Ischemia, where blockages have become so severe that legs and feet are no longer receiving blood flow.
The degree of PAD depends on when it is diagnosed and other present risk factors such as smoking, high cholesterol, heart disease and diabetes.
The Toe-Brachial Index (TBI) Process
The test is performed using a photoplethysmograph (PPG) infrared light sensor on the left finger and the right toe, while the patient is in a reclining position. The resultant Toe-Brachial Index (TBI) is generated using readings from the finger and toe. A TBI reading is done for each leg.
0.75 TBI is considered normal.
State-of-art measures for determining blood pressure via central aortic blood pressure are now readily available. These methods utilize oscillometric or tonometric readings of arterial pressure curves (brachial artery, radial artery) to generate central blood pressure measure and ultimately determine central blood pressure.
The physiological relationship between blood pressure amplification and increasing arterial stiffness as associate to the arterial vascular system produces peripheral systolic blood pressure (SBP) values that average 10-15 mmHg higher than central (aortic) systolic blood pressure. This scenario is only apparent during the systole stage. Meanwhile, diastolic pressure in the upper arm and aorta remain unchanged.
In addition, central SBP increases with advancing age. This increase is even more significant than the increase in peripheral SBP such that higher age produces a central SBP value that is higher than the peripheral SBP. This finding suggests the notion that with increases central SBP come an increased cardiovascular risk even when peripheral blood pressure readings are within the normal range. Recent studies concur that central blood pressure presents a superior opportunity for prognosis.
For these scenarios, regardless of long-term research, , intensive antihypertensive therapy is a recommended course of action in combination with medication that widens blood vessels (ACE inhibitors, AT1 antagonists, renin inhibitors, calcium antagonists). These drug treatments promote a more substantial reduction in central blood pressure than conventional antihypertensive drugs (beta-blockers, diuretics).