The arterial pulse is one of the most basic and important signs in medicine. Since ancient times, it has been closely associated with physicians and the practice of medicine. In fact, Pulse Wave Analysis (PWA) can provide valuable insights into cardiovascular health by examining the pulse waveform. Therefore, it’s important to understand exactly what a pulse wave is.
What is a pulse wave?
A pulse wave is created when the heart pumps blood into the central and peripheral arteries during the contraction phase, known as ventricular systole. This action causes a sudden increase in blood pressure. Since this pressure change starts at the heart and travels through the arterial system, pulse waves carry a wealth of clinical information about the cardiovascular system’s function and condition.
Pulse Wave Analysis – An overview
Pulse wave analysis (PWA) is a sophisticated technique employed to first measure peripheral pressure waveforms and then allows for the precise calculation of central pressure waves. Consequently, it provides physicians with critical parameters such as the augmentation index and central blood pressure, which are essential for evaluating cardiovascular health.
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What is Augmentation Index?
In fact, the Augmentation Index (AIx) is an indirect, rather than a direct, measure of arterial stiffness. AIx is less time-consuming and easier to measure than Pulse Wave Velocity (PWV). Additionally, unlike PWV, AIx can be adjusted more easily and quickly by medication in people with hypertension.
During systole, each pulse pressure waveform shows two peaks. Augmentation Pressure is calculated by analyzing these two peaks: the first peak is caused by blood being pumped from the heart, and the second peak is due to the reflected wave from resistance in smaller arteries. Augmentation Pressure measures how much the reflected wave adds to the initial pressure wave.
It should be noted that the Augmentation Index (AIx) has the advantage of being a dimensionless and relative measure, meaning it can be calculated from waveforms without the need for calibration.
Understanding the Augmentation Index:
The Aortic Augmentation Index (AIx) primarily reflects the resistance in the small arteries and arterioles in the periphery. This resistance is influenced by the production of nitric oxide (NO) by the endothelial cells lining the blood vessels. A normal AIx value for the aorta is considered to be below 33%. This means that if the AIx value is higher than 33%, it may indicate indirect increased arterial stiffness or higher peripheral resistance.
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What is Central Systolic Blood Pressure?
Central systolic blood pressure (SBPao) is the pressure in the aorta that carries blood from your heart. This pressure affects important organs like your heart, brain, and kidneys. In fact, central systolic blood pressure is more important than peripheral pressures for understanding and predicting cardiovascular disease.
How to manage and treat central blood pressure?
Central and peripheral blood pressure values can differ significantly, influencing treatment approaches. Central blood pressure is especially valuable in diagnosing isolated systolic hypertension in young individuals, where it can clarify whether elevated peripheral readings are benign or indicative of early arterial stiffening.
As we move farther from the aorta, blood pressure tends to increase. Central systolic blood pressure is usually lower than peripheral systolic pressure, often by about 10 mmHg, and is normally below 140 mmHg. Understanding these differences is important for accurately diagnosing and effectively managing hypertension.
For instance, beta blockers were less effective than calcium channel blockers, ACE inhibitors, AT1 antagonists, or diuretics in reducing central aortic systolic blood pressure. This finding may lend support to recent studies that question the efficacy of beta blockers as the optimal treatment for uncomplicated hypertension.
Pulse wave analysis measurement device
As discussed, pulse wave analysis is crucial for assessing cardiovascular health. This technique helps in determining how effectively the cardiovascular system is functioning. There are NOT several devices available on the market that use non-invasive methods and can reliably measure central blood pressure and augmentation index.
Among these devices, the Arteriograph is considered the gold standard. It is widely recognized and used in clinical settings for pulse wave analysis due to its accuracy and reliability. The Arteriograph’s ability to provide consistent and precise measurements makes it a valuable tool for diagnosing and managing cardiovascular conditions.