The Link between Aortic Stiffness and Cardiovascular Disease
Dec 5, 2016 by Dr. Jess Goodman | health
Aortic Stiffness Directly Related to Cardiovascular Disease Risk
Heart disease is the most common cause of death and kills one in four people. What if it was possible to identify people at high risk for heart disease when they were as young as 30 years old? In fact, using measurement of Aortic Stiffness this can be done today. Even more incredibly Aortic Stiffness can objectively show risk of heart disease decreasing with attention to exercise, diet and stress management.
For over twenty years medical scientists have known that stiffness of the Aorta, the body’s largest blood vessel running from the heart through the chest and abdomen, can be used to predict the risk of heart disease. This risk is related to waves that travel along the Aorta and affect function of the heart.
With each heartbeat a wave is generated that travels along the walls of the body’s entire arterial tree including the Aorta. This wave, the Primary Wave, travels down the Aorta and when the Aorta branches and divides in the abdomen and pelvis, reflections of the Primary Wave are formed that travel back to the heart. The reflections sum together to form a single Reflected Wave.
In a young person the Reflected Wave travels up the Aorta and arrives back at the heart just as the heart completes a contraction and enters its relaxation phase. The Reflected Wave maintains pressure in the Aorta, inducing blood to flow into the Coronary Arteries feeding the heart muscle while it is resting. The timing is subtle and a feat of divine engineering.
As we age and the Aorta stiffens, the Primary and Reflected Waves travel more quickly down and then back up the Aorta. In a middle aged person, the Reflected Wave returns to the heart early enough to meet the outgoing Primary Wave. The two waves crash together like two waves in the ocean. Blood Pressure is increased as the Primary and Reflected Wave’s pressures add together. This is the basis for the condition known as Essential Hypertension, commonly known as high blood pressure. Hypertension has harmful effects on the heart and other organs including the brain (linked to Dementia) and the kidneys (linked to kidney failure).
In the diagram of fingertip arterial pulse shapes shown below, the Older pulse shows the Reflected Wave arriving well before the peak and causing an augmentation in pressure. In the Younger pulse the Reflected Wave arrives late in the pulse and just before the notch caused by closure of the Aortic Valve at the end of the heart’s contraction phase.
Early return of the Reflected Wave and the resulting increased pressure makes it more difficult for the heart to eject blood into the Aorta and the heart muscle has to work harder. Over time this results in the heart muscle getting thickened, a condition known as Ventricular Hypertrophy that leads to heart failure.
When the Reflected Wave arrives early, during the heart’s contraction phase, there is less pressure to drive blood into the Coronary Arteries during the hearts relaxation phase. This results in the heart muscle not getting as much blood flow, oxygen and nutrients. Over time this leads to abnormalities in the Coronary Arteries and can result in narrowing of the Coronary Arteries, angina and heart attack.
There have been many scientific studies establishing that Aortic Stiffness is a good way to predict risk of heart disease, stroke and dementia. Recent studies have also shown that increased Aortic Stiffness of people in their 30’s predicts risk of later development of heart disease. This increased risk detected by Aortic Stiffness measurement is apparent before high blood pressure, high cholesterol or other conventional risk factors are apparent.
Perhaps the most exciting scientific reports note that with exercise Aortic Stiffness can be lowered. These studies found that people with the highest level of Aortic Stiffness got the most benefit from fitness training and that the more intense the exercise the more dramatic the result.
iheart uses a precision fingertip optical sensor to capture the pulse signal and sophisticated bio-signal analysis routines to identify the Reflected Wave in the fingertip pulse signal. In everyone of the thousands of people who have used iHeart the Reflected Wave can be identified.
Shown below is the iheart method of looking at the ‘derivatives’ of the pulse signal to find subtle changes associated with the Reflected Wave. The red line is the point where the Reflected Wave appears. iHeart uses identification of the Reflected Wave onset point to create a Reflected Wave index used to calculate Internal Age, an estimate of Aortic Stiffness.
Seen below is the iheart Pulse Analysis screen shown after a recording finishes. This screen shows a ‘older’ pulse wave shape. iheart uses the term Internal Age to make it easy to know if your Aortic Stiffness is that of a person younger or older than your chronological age.
iheart makes it easy to follow changes in Aortic Stiffness by providing a trending screen to see how your Internal Age changes over days, weeks and months as you try diffident healthy activities such as walking, eating fish rich in Omega-3 fatty acids and starting to learn Yoga.
Aortic Stiffness is a powerful health metric that can guide you towards better health and longer life. The iheart system is a simple and easy way to use Aortic Stiffness in an intuitive and fun way.
The iheart system is not intended to be used as a medical device. iheart is not useful for medical diagnosis or treatment. iheart is intended only for personal health and wellness education.