Cardio Age- What Is It and Why Should I do This Test?
The standard blood pressure cuff was introduced into medical practice well over 100 years ago, and it allowed the routine, measurement of arterial blood pressure. High blood pressure rarely causes significant symptoms, but is strongly related to future cardiovascular risk (1). Hypertension is the leading cause of death and disability worldwide, and evidence from over 50 years of study have shown that lifestyle interventions and medications that lower blood pressure significantly reduce risk (2,3). It's because of this, every doctor you visit and every pharmacy has a blood pressure cuff. The main driving force between the continued use of traditional blood pressure cuff use is ease of measurement and low cost, but we have known for decades that this may not be THE BEST predictor of heart attack and stroke risk!
Recent studies have shown that the pressure in the artery coming OFF OF the heart (aorta) is a much better predictor of risk and that and having a central pressure, ≥ 50 mmHg, doubled the risk of heart attack or stroke in both men and women in young and old, with or without diabetes (4)!
Your circulatory system is like a tree
Your heart pumps blood first through the big arteries coming off of the heart, then through a network of smaller and smaller arteries until finally it reaches the tiny capillary beds in your organs and muscles. Think of this like a tree. The trunk reaches up and then splits off into smaller and smaller branches ending with the tiny veins that supply the entirety of each leaf and provide nourishment for each part of the tree to grow. The circulatory system is closed loop so the pressure within it will change based on the size of the vessels the blood travels through. The pressure in each part of the circulatory system will be different and depend on factors such as the diameter of the vessels, the rate of blood flow and changes to the vessels themselves.
What is arterial stiffness and why does it matter?
As the blood flows first from the heart then through the arteries, to the capillaries and back to the heart, a pressure wave is generated. Because the system is a closed loop and blood is also flowing back to the heart, there is also a pressure wave flowing backwards in the opposite direction. When the heart relaxes between contractions the waves meet and this wave of blood is used to nourish the heart muscle itself.
With ageing and cardiovascular disease, the arterial wall thickens and the arteries get stiffer. As a result, the pressure waves travel faster and the reflected pressure wave returns during the contraction phase of the heart, increasing systolic blood pressure and thus increasing the amount of blood in the left ventricle left all while decreasing the life-giving oxygen to the heart muscle itself (5). Conventional blood pressure measurements are commonly used to measure arterial pressure and do not measure reflected waves, or the additional pressure exerted on the heart from stiff arteries. More recently, it has been acknowledged that central pressure may not be the same as that measured at the arm (7,8). This was demonstrated in a huge trial where the where data from 10,600 individuals showed that central pressure cannot be reliably inferred from peripheral blood pressure due to the variation in the gradient between central and peripheral pressures (9).
How is arterial stiffness measured?
In addition to the traditional systolic and diastolic blood pressure measured at the arm, we can now measure the shape of the wave of pressure from the heart and back (called the waveform). The most widely used device in clinical studies is the SphygmoCor device, which we have brought to New Zealand to help our patients better understand their risk of having a heart attack or stroke. This device allows for two types of pressure wave measurement to be performed non-invasively using the gold standard techniques used in studies (10). This is exactly the device we use for our Cardioage testing! It's time to bring blood pressure measurement to the modern era as it is still the leading killer of men and women in the developed world!
The SphygmoCor® for Central Arterial Pressure Waveform Analysis
SphygmoCor is a non invasive clinical test that measures the pressure waveform at the heart, helping physicians better understand a patient’s high blood pressure, because no two patients are alike! These measurements have been shown in multiple studies and for over half a century to be more accurate at predicting your risk of heart attack or stroke than arm blood pressure alone. The results are important in managing treatment and reducing damage to the heart, kidneys and other organs.
SphygmoCor measures the pressure waveform at the heart, which is important in managing treatment and reducing damage to end organs like the heart, brain and kidneys. It also gives valuable information on how stiff your arteries are and how much blood your heart is supplied each time it relaxes. As we age our arteries become stiffer and the test report shows you how you compare to other men and women in your age group, helping to predict your “cardioage”
Why is this procedure important?
This waveform information is different than the blood pressure in the arm.
Doctors have long known that this information, measured at the heart, is the most clinically important and more accurately predicts risk of heart attack and stroke
The results can help your doctor better manage your blood pressure and may help with treatment decisions and monitor your medication
How does the SphygmoCor System work?
The SphygmoCor test uses a cuff placed around the upper arm like standard blood pressure. The machine connected to the cuff has special sensors that measure the pulse waveform.
How are the test results used?
To give your health care provider additional information to manage your blood pressure
To see how diet, exercise and medication therapy are improving your test results and risk