How does the EndoPAT® measure endothelial function?
The test will take approximately 20 minutes. You will be asked to lie down for the test and roll up your sleeves. A blood pressure cuff will be wrapped around your arm and fingertip sensors will be placed on both index fingers. Later, the blood pressure cuff will inflate for 5 minutes.
When the blood pressure cuff is inflated, blood flow to the finger will temporarily stop. Later, when the cuff is released, the strong flow of blood stimulates the arteries to dilate and deliver more blood to the finger. Blood flow will be measured by the finger sensor to assess how well the arteries dilate.
Normal response is characterized by a significant dilatoin of the arteries after the blood cuff is released. If arteries fail to dilate sufficiently, the condition is described as Arterial dysfunction (Medical term: Endothelial dysfunction).
Can the test been performed on children?
We rely on the medical judgment and expertise of the physician regarding the precise patient population. Although most of the testing on EndoPAT® has been done on adults, there are many ongoing and published studies with the EndoPAT® on children and adolescents. There is no special design of the biosensors for children, however. The length of the EndoPAT® biosensor is 5cm, thus the length of the finger of the child must be at least as the length of the biosensor.
Selamet et al* tested prospectively the reproducibility and feasibility of the EndoPAT® in adolescents. EndoPAT® tests were performed on two different days separated by no more than seven days in 30 healthy fasting adolescents, ages 13 to 19 years. The authors concluded, “In healthy adolescents, Endo-PAT is feasible and has excellent reproducibility.” Moreover, the authors stated, “This technology may provide an easy and reliable means of assessing endothelial function in the pediatric population.”
* Selamet Tierney ES, Newburger JW, Gauvreau K, Geva J, Coogan E, Colan SD, Ferranti SD. Endothelial Pulse Amplitude Testing: Feasibility and Reproducibility in Adolescents. J Pediatr. 2009; 154(6):901-5.
Can the EndoPAT® help predict endothelial dysfunction and cardiovascular events?
Results of a 2009 study conducted by researchers at the Mayo Clinic and Tufts reported that the EndoPAT® test is “highly predictive” of a major cardiac event, such as a heart attack or stroke, for people who are considered at low or moderate risk based on their Framingham Risk Score (FRS).
The FRS is the commonly used risk predictor and was developed from the Framingham Heart Study, an ongoing longitudinal study of heart disease.
In this Mayo Clinic study, published in the Journal of the American College of Cardiology, Amir Lerman, M.D., a cardiologist at Mayo Clinic and senior author of the study, and other researchers, used an EndoPAT® to measure the endothelial health of 270 patients between the ages of 42 and 66 and followed their progress between 1999 and 2007.
These patients already knew that they had low-to-medium risk of experiencing a major adverse cardiac event, or MACE, based on their FRS. Some of their risk factors included high blood pressure, high cholesterol, obesity, and a family history of heart disease.
The study results: The rate of MACE in patients who tested positive for endothelial dysfunction was 39% vs. normal endothelial function 25% (p=0.024). The study showed that patients at low FRS risk but with endothelial dysfunction were at a higher actual risk of future CV events than patients with high FRS but normal endothelial function.
Furthermore, endothelial dysfunction was found to be an independent risk factor for future MACE on multivariate analysis (p=0.002).
* Rubinshtein R, Kuvin JT, Soffler M, Lennon RJ, Nelson RE, Pumper GM, Lerman LO, Lerman A. Assessment of Endothelial Function by Peripheral Arterial Tonometry Predicts Cardiovascular Events Beyond the Framingham Risk Score. JACC 2009; Suppl.
Does it matter which fingers are used for the test?
Any finger but the thumb may be used. But placement of the sensors on the index fingers is recommended. Due to variance between fingers in blood supply symmetrically-paired fingers on both arms should be used (i.e. either both index fingers or both middle fingers). The thumb should be avoided.
Who should have an EndoPAT® test?
The earlier you diagnose a cardiac condition and initiate a cardio-protective program, the better off you are. Candidates include men between the ages of 40 and 70 and women between the ages of 50 to 70 with one or more of the following risk factors for heart disease:
• Cigarette smoking
• Elevated cholesterol level
• Family history of heart disease (sudden death, heart attack, or need for angioplasty or bypass surgery) in a first-degree male relative (parents or siblings) 55 years old or less, or a first-degree female relative 65 years old or less.
• High blood pressure
• Sedentary life style
If you have multiple risk factors, or one particularly severe risk factor, you need to talk to your physician about earlier intervention. For example, if you are a 35-year-old male and your father died at the age of 41 of a heart attack, an EndoPAT® test would be warranted.