What’s New?

Researchers have identified vascular age and its indicator, pulse wave velocity (PWV), as important metrics for assessing and enhancing lifespan and healthspan. They have also developed methods to make these metrics more accessible.

Why This Matters

Understanding vascular age and the rate of aging serves as crucial benchmarks for evaluating the impact of lifestyle choices and health interventions. Utilizing these metrics can significantly boost your chances of achieving a long, healthy life.

What You Can Do

I have adapted these tools for everyday use, making them accessible for anyone interested in improving their health. If you had to select one biomarker to help you determine when you might need a fire extinguisher for your birthday cake, which would it be?

If you chose pulse wave velocity, well done! Few biomarkers correlate as strongly with healthy life expectancy as PWV does (aside from cardiorespiratory fitness, which I discussed previously). It provides critical insights into the health of your arteries.

A Brief Historical Overview

For over three centuries, arterial age has been viewed as a marker of longevity in medical science. In the 17th century, Thomas Sydenham, an English physician, famously stated, “Man is as old as his arteries.” This encapsulates the notion that arterial age reflects how well lifestyle choices align with genetic predispositions. This concept explains why individuals of the same chronological age can exhibit vastly different levels of functional health and physical appearance.

What Dr. Sydenham lacked was a method to measure and manage arterial age to avoid premature aging and decline. This question has since been addressed. Despite 44,000 papers published on the topic in the last 50 years, arterial age isn't as widely recognized or utilized as basic oral hygiene (which has 40,000 papers in the same timeframe).

In this article, I aim to bring the findings of my colleagues from academic circles into your personal longevity toolkit. I will also provide a downloadable Excel file to help you calculate your PWV and arterial age.

Understanding Pulse Wave Velocity (PWV)

PWV refers to the speed at which the blood pressure wave travels through the arteries. When the heart pumps blood from the left ventricle into the aorta, the pressure in the aorta rises. This pressure wave is recorded as systolic blood pressure (the upper value) at the measurement site, commonly the upper arm. PWV is measured in meters per second, typically ranging from below 5 to over 20 m/s.

Measuring PWV

To measure the speed of anything, you need two points of measurement, the distance between them, and the time taken to cover that distance. The most common sites for measuring PWV are the brachial (upper arm) and ankle, leading to the term brachial-ankle PWV (baPWV). Alternatively, measurements can be taken between the carotid (neck) and femoral (upper thigh) arteries, known as carotid-femoral PWV (cfPWV).

Although the precise length of the arterial path between these measurement points is uncertain, consistent estimation methods based on height and body markers allow for comparability across different labs. While these estimates may not be perfectly accurate, they are reliable enough for meaningful comparison of your personal PWV against established norms for your age and gender.

The advantage of having a vast array of PWV measurements is the ability to identify other biomarkers that correlate well with PWV but are easier to measure. This was demonstrated by a research team led by Greve in 2016. The ability to estimate PWV (ePWV) without laboratory equipment is particularly beneficial for epidemiological studies involving large populations.

However, it's crucial to note that ePWV is an estimate rather than a direct measurement. When investing in tailored solutions, precise measurements are necessary to ensure accuracy.

A recent innovation has emerged that allows for PWV measurement in a more accessible way. The company Withings developed a bathroom scale that uses ballistocardiography (BC) to measure PWV while you weigh yourself. BC detects the force generated by the blood's ejection into the aorta, determining the timing of the pulse wave. It also notes the arrival time of the pressure wave at the foot, providing all necessary data to calculate PWV.

I want to clarify that I have no affiliation with Withings. I do not receive any financial benefits from them, nor do I have affiliate links. Purchasing their scale does not benefit me in any way.

I use the Withings scale alongside my clinical equipment for two reasons: it is the only PWV device suitable for personal use and has been independently validated.

How PWV Relates to Arterial Age

First, let’s define aging. Although there’s no universal definition, many researchers agree on a practical description: "Aging is the progressive decline of function with increasing chronological age." This definition is straightforward and applicable.

Function is measurable on both a whole-body level (consider fitness) and at the level of specific systems, such as the arterial system. The arterial system's function extends beyond merely serving as conduits for blood; arteries actively contribute to blood circulation.

The heart pumps approximately 80 ml of blood with each beat, translating to nearly 5 liters per minute, or 6900 liters daily, throughout one’s lifetime. By age 80, the heart will have circulated enough blood to fill three massive oil tankers.

Fortunately, arteries aid this process. Each time blood is pumped into the aorta, it expands and then contracts elastically, akin to a rubber band. This elasticity is crucial for effective blood flow; if the arteries are too rigid or worn out, blood flow is compromised, leading to increased PWV.

The Moens-Korteweg equation illustrates the relationship between PWV, arterial stiffness, wall thickness, and radius. As such, PWV serves as a valuable indicator of arterial health.

Summarizing, increased PWV corresponds with reduced arterial elasticity and greater arterial age, making PWV a reliable marker of vascular health.

Understanding the Importance of PWV and Vascular Age

Vascular aging can manifest in three scenarios: unfavorable (EVA), favorable (SUPERNOVA), and a middle ground (normal aging). In all cases, PWV plays a pivotal role.

In the EVA scenario, vessels narrow and become thicker and stiffer, leading to increased PWV. Conversely, SUPERNOVA reflects a widening of the lumen (often due to high-intensity exercise) and preserved arterial elasticity, resulting in lower PWV compared to normal aging.

EVA and SUPERNOVA have been recognized as independent predictors of future cardiovascular health, with PWV being the most reliable indicator.

PWV and Dementia

Dementia is a significant concern for many individuals. A systematic review and meta-analysis have shown a negative correlation between arterial stiffness and cognitive function over time.

It's essential to differentiate between associations derived from cross-sectional studies and the causal relationships inferred from longitudinal studies. The latter is less common but strengthens the association between PWV and cognitive decline.

Researchers have identified PWV as an independent predictor of cardiovascular events, enhancing the predictive capabilities of current risk assessment models.

Improving Your PWV and Vascular Age

Yes, you can enhance your PWV and vascular age to mitigate health risks. The aforementioned researchers suggest that PWV assessments could help identify individuals at risk for cognitive decline and inform interventions to slow the progression of dementia.

The endothelium, the inner lining of blood vessels, plays a vital role in maintaining arterial elasticity through the production of nitric oxide (NO). Regular exercise is one of the best ways to support endothelial health, followed by dietary adjustments.

Optimizing Your PWV and Vascular Age

For Europeans, monitoring PWV is simpler than for Americans due to regulatory differences. The Withings app provides PWV values alongside vascular age, while FDA regulations prevent this in the U.S.

However, you can download your data from Withings and enter PWV values into the Excel file I created.

The Excel file allows you to enter data such as age, blood pressure, gender, height, and heart rate to estimate your PWV and vascular age.

Option 1: ePWV and Vascular Age

This option provides your estimated PWV and vascular aging category, along with the 10th and 90th percentiles that indicate thresholds for SUPERNOVA and EVA.

Option 2: Estimated baPWV and Vascular Age

This option focuses on baPWV and is based on our research, which indicates that baPWV correlates better with aging and disease than cfPWV and ePWV.

Option 3: Withings-Derived Vascular Age

If you own a Withings Body Cardio scale, you can enter your PWV to receive an estimate of your vascular age. However, our reference ranges may provide more precision than the app's general categorizations.

An Invitation

If you’re interested in experimenting with lifestyle changes to improve your vascular age, you can use our LiLo web application, provided you have a Withings scale. This tool automatically pulls your PWV data, allowing you to monitor changes over time.

I invite you to share your findings with Medium readers anonymously. I plan to publish an article detailing the results, including my own experiences.

If you're interested, please let me know in the comments. I'll respond within 48 hours, although it may take longer on weekends.

Conclusion: A Lasting Impression of Sydenham’s Insight

At 57, I was profoundly affected by Dr. Sydenham’s insight during a clinical assessment. A patient, the same age as me, presented with severe vascular issues, highlighting the consequences of lifestyle choices. In contrast, a vibrant 92-year-old demonstrated the benefits of healthy living. Their experiences reaffirm the impact of personal health decisions.

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References

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[2] Greve S V, Laurent S, Olsen MH. Estimated Pulse Wave Velocity Calculated from Age and Mean Arterial Blood Pressure. Pulse 2016;4:175–9. doi:10.1159/000453073.

[3] Campo D, Khettab H, Yu R, Genain N, Edouard P, Buard N, et al. Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale. Am J Hypertens 2017;30:876–83. doi:10.1093/AJH/HPX059.

[4] Cohen AA, Kennedy BK, Anglas U, Bronikowski AM, Deelen J, Dufour F, et al. Lack of consensus on an aging biology paradigm? A global survey reveals an agreement to disagree, and the need for an interdisciplinary framework. Mech Ageing Dev 2020;191:111316. doi:10.1016/j.mad.2020.111316.

[5] Bruno RM, Nilsson PM, Engström G, Wadström BN, Empana JP, Boutouyrie P, et al. Early and supernormal vascular aging: Clinical characteristics and association with incident cardiovascular events. Hypertension 2020:1616–24. doi:10.1161/HYPERTENSIONAHA.120.14971.

[6] Alvarez-Bueno C, Cunha PG, Martinez-Vizcaino V, Pozuelo-Carrascosa DP, Visier-Alfonso ME, Jimenez-Lopez E, et al. Arterial stiffness and cognition among adults: A systematic review and meta-analysis of observational and longitudinal studies. J Am Heart Assoc 2020;9:e014621. doi:10.1161/JAHA.119.014621.

[7] Kim HM, Rhee TM, Kim HL. Integrated approach of brachial-ankle pulse wave velocity and cardiovascular risk scores for predicting the risk of cardiovascular events. PLoS One 2022;17:1–12. doi:10.1371/journal.pone.0267614.

[8] Kraushaar LE, Dressel A, Massmann A. A novel principled method for the measurement of vascular robustness uncovers hidden risk for premature CVD death. J Appl Physiol 2018;125:1931–43. doi:10.1152/japplphysiol.00016.2018.