What is the role of carotid femoral pulse wave velocity (cfPWV) in assessing cardiovascular risk in patients undergoing anesthesia, particularly those with known or suspected cardiovascular disease?

Carotid-Femoral Pulse Wave Velocity in Perioperative Cardiovascular Risk Assessment

Carotid-femoral pulse wave velocity (cfPWV) should be measured preoperatively in patients with known or suspected cardiovascular disease undergoing anesthesia to provide incremental cardiovascular risk stratification beyond traditional risk factors, with values >10 m/s indicating significantly elevated perioperative risk. 1

Why cfPWV Matters in Anesthesia

cfPWV is the gold standard measurement of arterial stiffness and independently predicts major adverse cardiovascular events including myocardial infarction, stroke, and cardiovascular death. 1 The American Heart Association provides Class IIa recommendation (Level of Evidence A) that measuring arterial stiffness provides incremental information beyond standard cardiovascular disease risk factors in predicting future cardiovascular events 1.

Prognostic Value for Surgical Patients

• Each 1 m/s increase in cfPWV confers a 12% increased risk for cardiovascular events and 9% increased risk for cardiovascular mortality 2
• Each 1 standard deviation increase in cfPWV increases cardiovascular event risk by 25% and cardiovascular mortality by 23% 2
• The predictive value is particularly strong in younger patients where early identification allows for risk modification 1

Measurement Standardization

Distance Calculation (Critical Technical Point)

Use either the "subtraction method" (suprasternal notch-to-femoral minus suprasternal notch-to-carotid) or the "0.8 method" (80% of direct carotid-to-femoral distance) to avoid overestimating aortic PWV by up to 2.9 m/s. 1 The direct carotid-femoral measurement substantially overestimates true aortic PWV and should be avoided 1.

Measurement Technique

• Record pulse waveforms simultaneously at carotid and femoral arteries using tonometry 1
• Gate measurements to the R-wave peak on ECG to determine transit time 1
• Always measure blood pressure simultaneously with cfPWV, as mean arterial pressure is a critical determinant of arterial stiffness 1
• Use calipers for distance measurements, particularly in overweight/obese patients 1

Risk Thresholds for Perioperative Assessment

A cfPWV threshold of >10 m/s indicates significantly elevated cardiovascular risk in middle-aged and older adults. 1 This threshold was adjusted from the original 12 m/s to account for the 0.8 distance correction factor 1.

Risk Stratification Algorithm

• cfPWV ≤10 m/s: Standard perioperative cardiovascular risk
• cfPWV >10 m/s: Elevated risk requiring enhanced monitoring and potentially modified anesthetic management 1
• In hemodialysis patients specifically, cfPWV >10 m/s independently predicts both cardiovascular and all-cause mortality 3

Clinical Applications in Anesthesia

Preoperative Risk Assessment

cfPWV substantively reclassifies cardiovascular risk in intermediate-risk patients, with net reclassification improvement of 10.8% when patients with cfPWV ≥10 m/s are moved to higher risk categories. 4 This reclassification is particularly valuable for:

• Patients with hypertension undergoing major surgery 1
• Diabetic patients (who show greater differences between aortic and carotid stiffness) 1
• Patients with established cardiovascular disease 1

Hemodynamic Implications

Increased arterial stiffness causes widening of pulse pressure, increased blood pressure lability, and impaired baroreceptor sensitivity—all critical considerations for intraoperative hemodynamic management. 1 A stiffened vasculature is less able to buffer short-term alterations in cardiac output during anesthesia 1.

Alternative Measurement Methods

Brachial-Ankle PWV (baPWV)

While baPWV correlates with cfPWV (r = 0.73) and shows similar associations with cardiovascular risk factors, it measures both elastic and muscular arteries, making interpretation ambiguous for true aortic stiffness assessment. 1, 5 The conversion formula is: cfPWV = 0.833 × baPWV + 2.333 1.

• baPWV values are approximately 20% higher than cfPWV 5
• More commonly used in Asian populations 1
• Less anatomically relevant than cfPWV for assessing central aortic properties 1

Estimated PWV (ePWV)

ePWV calculated from age and mean blood pressure alone can predict cardiovascular events independently of traditional risk scores, though direct cfPWV measurement remains preferable when available. 4 The mean difference between ePWV and measured cfPWV is only -0.3% (95% CI -15% to 17%) 4.

Common Pitfalls to Avoid

• Never use direct carotid-to-femoral distance without the 0.8 correction factor—this overestimates PWV by approximately 30% 1
• Avoid single-site cuff-based devices claiming to measure PWV from brachial pressure alone—these use flawed assumptions about uniform arterial tubes and cannot physically measure true PWV 1
• Do not rely on augmentation index as a surrogate for arterial stiffness—it is a poor measure of wave reflection compared to direct PWV measurement 1
• Account for obesity and arterial tortuosity—body surface measurements may not represent true arterial path length in these patients 1

Integration with Cardiovascular Risk Scores

cfPWV adds independent predictive value beyond both SCORE and Framingham risk scores, indicating that traditional risk scores underestimate the complex impact of age and blood pressure on arterial stiffness. 4 This is particularly relevant because cfPWV shows relatively modest correlation with standard risk factors other than age and blood pressure 1.