Sacramento Heart Center | B Pro APulse CASP

Q & A for Arterial Pulse Waveform
for BPro® A-PULSE CASP
Introduction:
A-PULSE CASP is a revolutionary product patented by
HealthSTATS International Pte Ltd available through
My PulseWave for Integrative Medicine screening. It is
able to measure accurately the Central Aortic Systolic
Pressure (CASP), which is the blood pressure at the root
of the aorta. It is the only device which can be used in
common clinical setting. CASP has been shown in many

recent studies as an important determinant for strokes
and CVS events. It has been validated via invasive
study and achieved an accuracy (co-relation) R= 0.9917
independently. A-PULSE CASP is FDA and CE MDD
approved. It is also being used in large drug trials by
Pharmaceutical companies. A-PULSE CASP is now
available through the Synergy Worldwide network.

1. What is arterial pulse
waveform?
When the left ventricle ejects blood into the
aorta in systole, the perturbation generates
a wave that initially travels through the
arteries from the heart towards the arterial
tree.
Pulse waveform has 2 components.
1. Forward traveling wave when the left
ventricle contracts and
2. Reflected wave returning back from the
peripheral.
3. Diagrammatic Representation of a
Radial Arterial Pulse Wave
Figure 1. Diagrammatic Representation of a Radial Arterial Pulse
Wave

This is the blood pressure at the root of the
aorta or the largest artery in the body, as the
blood is being pumped out of the heart. This
pressure is called Central Aortic Systolic
Pressure or CASP. CASP has been shown
to be an important factor in the relation to
strokes and cardiovascular events, more so
than the brachial pressure, or the pressure at
the arm commonly.

Figure 2. Radial Wave Pressure

BPro®

2. What is CASP (Central
Aortic Systolic Pressure)?

Q & A For Arterial Pulse Waveform

3. How to measure CASP?
3.1 Invasive method
This is direct measurement and has been considered as the most accurate method. To perform the measurement, a
catheter must be inserted into the aortic root from brachial or femoral artery, which is obviously an invasive method
and could result in complications (Fig. 3). This invasive method of measuring CASP is not available in clinical setting.
However, A-PULSE CASP can be used in clinic and the accuracy has been validated against this invasive method, the
result is R= 0.9917 (co-relation).

3.2 Non-invasive method
HealthSTATS (HS) invented a device named BPro® which is able to capture radial pressure waveforms. Furthermore,
HS developed a proprietary formula to derive central aortic systolic pressure (CASP) from the calibrated radial
Figure 3. Direct measurepressure waveform (Fig. 4).
ment of CAP using catheter

4. What is augmentation index?

Figure 4. Non-invasive measurement of CASP using HealthSTATS BPro® device and APULSE software.
The difference between the second and first systolic peaks expressed as a percentage of the pulse pressure.

5. What is the arterial compliance?
The ability of an artery to increase the volume in response to a given increase in blood pressure is called compliance.

6. What is pulse wave velocity?
PWV is the speed at which the pressure waveform travels (wave propagation) along the aorta and large arteries, during
each cardiac cycle.

7. What is applanation tonometry?
The principle of applanation tonometry is that the force acting on the plunger is proportional to the pressure in the
artery when where the artery surface is flattened.

8. How does CASP help hypertension diagnosis and treatment in primary care?

PAGE 2

To evaluate CASP in primary care, we must establish the normal range of CASP. Besides, guidelines of hypertension
management should be redesigned based on the stratification of CASP. More and more epidemic clinical studies need
to be done to consolidate the normal range of CASP for different races. BPro® and A-PULSE CASP can be used to
fulfill this task.

Sample Waveform of different age groups
19 years old
For a normal young person, where the arteries are generally compliant, the slow traveling reflected wave from the
peripheral occurs during diastole, thus enhancing perfusion of the coronary arteries.

Figure 5. Sample waveform of a 19 year old

47 years old
With age, the arteries stiffen. Pulse wave velocity increases and the reflected wave now travels faster and at a higher
amplitude, and occurs during systole. This has the effect of prolonging the systolic phase (increasing left ventricular
workload and oxygen requirements) but a compromise in coronary artery perfusion

Figure 6. Sample waveform of a 47 year old.

82 years old
In the elderly, further arterial stiffening causes the reflected wave to return much faster and at much higher amplitude;
and coincide very close to the systolic peak, resulting in an augmented wave. The heart now needs to contract even
harder (to overcome the oncoming reflected wave) and for a longer period. At the same time, coronary artery perfusion
is further compromised.

Figure 7. Sample waveform of an 82 year old.


Various indices captured by A-PULSE CASP
Systolic & Diastolic Pressure
The systolic pressure (SBP) is the peak pressure in the arteries
when the heart contracts while the diastolic pressure (DBP) is
the lowest pressure when the heart relaxes.

Pulse Pressure (PP)
PP is the difference between the systolic and diastolic pressure.
Normal PP in the brachial artery is approximately 40mmHg.
Increase PP may be due to several reasons, e.g. exercise
(temporary increase), anemia, Hyperthyroidism, arterial
stiffening (usually about 50-60 years)6.

Figure 8. SBP is the peak pressure while DBP is
the lowest pressure.

Central Aortic Systolic Pressure
(CASP)
Studies have shown that central pressure better represents
the load imposed on the coronary and cerebral arteries and
hence is more strongly related to vascular hypertrophy, extent
of atherosclerosis and cardiovascular events than brachial
pressure10-12.

Radial Augmentation Pressure (rAP) &
Radial Augmentation Index (rAI)

Figure 9. PP is the difference between the maximum and minimum pressures.

rAI is defined as augmented pressure as a percentage of pulse
pressure. It is also influenced by factors such as age and
gender. rAP is defined as the difference between 1st [SBP1]
and 2nd [SBP2] systolic peaks.

Peak Relative Time
It is the relative time between the 2 peaks. [T1-T2] In older
individuals (> 60), pulse pressure amplification (from central
SBP to peripheral SBP) is diminished as a consequence of
increased arterial stiffness and the early return of reflected
waves in the central arteries. Therefore, the relative timing of
the pressure waves merging (forward-backward traveling) may
be regarded as the third principal parameter that defines central
BP28. A higher peak relative time indicated that the degree of
arterial stiffness has increased.

Figure 10. CASP derived from proprietary formula
in A-Pulse™ CASP

Mean Arterial Pressure (MAP)

PAGE 4

Mean arterial pressure is the mean perfusion pressure
throughout the cardiac cycle. It is also the strongest
predictor for stroke and cerebrovascular mortality
as it also indicates the perfusion pressure of cerebral
circulation16.
Normal MAP should be 95±15mmHg. However, it is also
dependent on:

•

Age- older people tends to have higher MAP;

•

Sex- men have a wider deviation;

•

Ethnic group- so far, all data are available from the
western population. No data is available yet for the
Asian population.

BPro® Arterial Pulse Waveform
When the heart contracts a volume of blood is squeezed
into the Aorta causing it to stretch to accommodate this
new blood volume. Then as the vessel walls return to
normal, blood is pushed from the Aorta through the
arteries. This process of expansion and returning to
normal repeats with each beat of the heart as blood travels
through your arteries.
If you imagine for a moment that your blood was a strand
of pearls being pulled through a much smaller rubber
tube, then you will be able to think of circulation not as
a series of single beats but as a wave pattern of blood
flow. This simplified version of the complex process of
circulation does not take into account many aspects of
fluid dynamics; however, it does illustrate the two points
that I wish to discuss further which are wave patterns and
the importance of arterial elasticity.
Have you ever stood at the edge of a lake in the morning
when the water is calm and then toss a stone into the lake
just to watch the waves that are formed? If you have,
then you have seen the concentric circles that are formed
which travel away from the point where the stone entered
the water. If we exclude the effects of fluid dynamics as
we did earlier, then these waves would travel unchanged
to the other side of the lake. If these waves encountered
a rock or log along the way then they would bend around
the obstruction, thus altering the wave pattern, but still
would continue to the far shore. Now in our arteries
these rocks and logs represent build-ups inside the lining
of the artery or a stiffening of the artery wall which are
precursors to Atherosclerosis and Arteriosclerosis. By
analyzing the alterations of a Pulse Wave one can glean a
tremendous amount of information about the health and
elasticity of an individual’s arterial system.
The analysis of the pulse wave consists of measuring the
relationship between the forward traveling waves created
by the contraction of the heart and reflected waves that
travel back towards the heart created by resistance of the
arteries. These two wave forms overlap each other to
form the pulse wave. As an individual looses elasticity

in their arteries the reflected resistance waves increase
in intensity, further altering the pulse wave and these
changes can be measured.
There are primarily two different ways that you can noninvasively measure pulse waves. The first is to measure
the movement of the artery walls and the second is to
measure the flow of blood through the artery and then
from those measurements, estimate the movement of the
artery wall. Research facilities and hospitals generally
utilize technologies that specifically measure the artery
walls because it is through this type of measurement that
the greatest level of precision and accuracy is obtained.
I have always incorporated the highest level of testing
equipment available in our institute, because I closely
monitor the arterial elasticity of our patients. I need the
assurance that changes in the test results of a patient
are due to treatments and not fluctuations in the testing
equipment.
Other technologies that measure blood flow and then
extrapolate arterial wall movement are still valuable
tools because they provide information of the health and
elasticity of arteries; they are just prone to fluctuations
in test results. These fluctuations result from the rapidly
changing environment that exists inside our capillaries.
The most exciting thing I have seen with these type of
devices recently is the advances in the computer industry
which have shrunken the size of this technology to that of
a wristwatch and inexpensive enough for commercial use.
I believe that once more people become aware of the
importance of arterial elasticity and have access to testing
that only then will we have a chance at impacting the
staggering statistics of cardiovascular disease in positive
and meaningful way.
Daniel Austin, RN
High Desert Heart Institute
Victorville, CA

A Pulse CASP
SBP- Systolic Blood Pressure
The blood pressure when the heart is contracting. It
is specifically the maximum arterial pressure during
contraction of the left ventricle of the heart. The time at
which ventricular contraction occurs is called systole.

In a blood pressure reading, the systolic pressure is
typically the first number recorded. For example,
with a blood pressure of 120/80 (“120 over 80”), the
systolic pressure is 120. By “120” is meant 120 mm Hg
(millimeters of mercury).


DBP- Diastolic Blood Pressure
The diastolic pressure is specifically the minimum arterial
pressure during relaxation and dilatation of the ventricles
of the heart when the ventricles fill with blood.

In a blood pressure reading, the diastolic pressure is
typically the second number recorded. For example, with
a blood pressure of 120/80 (“120 over 80”), the diastolic
pressure is 80. By “80” is meant 80 mm Hg (millimeters
of mercury).

PP- Pulse Pressure
Blood pressure measurements include both a systolic
and a diastolic reading. These two readings are taken
at opposite ends of the cardiac cycle and are a person’s
highest and lowest blood pressure levels. The difference
between these two extremes is called the pulse pressure,
and represents the force that your heart generates each
time it contracts.

a person with a pulse pressure of 40 has normal blood
pressure. Consider these examples:

Equal Pulse Pressure Doesn’t Mean Equal Risk:

Clearly, a blood pressure of 140/100 is much different
than 120/80. These examples demonstrate that pulse
pressure, by itself, can’t be used to make treatment
decisions when other information is unavailable.

A person with normal blood pressure (120/80) will have a
pulse pressure of 40 (120-80). But that doesn’t mean that

•

Systolic Pressure = 120; Diastolic Pressure = 80;
Pulse Pressure = 120-80 = 40

•

Systolic Pressure = 140; Diastolic Pressure = 100;
Pulse Pressure = 140-100 = 40

MAP2- Mean Arterial Pressure
Based on the time weighted average of blood flow. MAP
is considered to be the perfusion pressure seen by organs
in the body. It is believed that a MAP that is greater than
60 mmHg is enough to sustain the organs of the average
person.

If the MAP falls significantly below this number for an
appreciable time, the end organ will not get enough blood
flow, and will become ischemic.

PR- Pulse Rate
CASP: Derived Central Aortic Systolic Blood Pressured
This value provides a non-invasive assessment of central
aortic blood pressure. Higher than normal values of
central aortic systolic blood pressure impact the organs of
the body and over time can cause organ damage. Normal
Ranges are from 106.0 to 119.5 over the age range of

Children age 10+ and adults:
Well-conditioned athletes:

60–100
40–60

20 years old to 90 years old. See attachment #1 for age
range details.

PAGE 6

rAI: Radial Augmentation Index
This is the index that compares the amplitude of the
reflected wave from arteries to the amplitude of the
forward traveling wave of blood flow created by the
contraction of the heart. This value is a percentage of the
reflected wave to the height of the forward wave pattern.
Lower numbers here indicate more elastic and pliable
arteries.

rAP: This is the blood pressure at the height of the
reflected wave pattern. Lower values here are better.
This is a measure of cardiac after-load and the efficiency
of the cardiovascular system.
PRT: This is the relative time interval between
the Systolic Blood Pressure peak and the reflected
augmentation peak.

Note: When the reflected wave comes back lower in amplitude and later in time then the arteries have a greater amount of arterial elasticity. Higher reflective waves
that rebound in shorter time intervals indicate stiff and less elastic arteries.

Sacramento Heart Center | B Pro APulse CASP

Recomendados

Recomendados

Mais conteúdo relacionado

Último

Último (20)

Destaque

Destaque (20)

Sacramento Heart Center | B Pro APulse CASP