Special Functions; Screening For Atrial Fibrillation During Blood Pressure Measurement; About Atrial Fibrillation; Central Blood Pressure Parameters - Microlife WatchBP Office Instruction Manual

Special Functions

Screening for atrial fibrillation during blood pressure measurement

The device is designed to screen for atrial fibrillation during blood pressure measurements
(optional) with high accuracy: a sensitivity of 98% and a specificity value of 92%*. If atrial
fibrillation is detected this will be shown in the report.

Verberk et al. Screening for atrial fibrillation with automated blood pressure measurement: Research evidence and practice
recommendations. Int J Cardiol 2016: 465–473.

About Atrial Fibrillation

Atrial fibrillation is a common heart rhythm problem and a common cause of major strokes.
It affects 8% of those 65 years and older and about 20% of all strokes are caused by atrial
fibrillation. Atrial fibrillation is a rhythm problem that can last from a few minutes, to days or
weeks and even years. Atrial fibrillation can lead to the formation of blood clots in the heart.
These clots can break off and flow to the brain causing stroke. One sign of atrial fibrillation is
palpitations. However, many people have no symptoms and therefore may remain undetected
whereas diagnosing atrial fibrillation early followed by adequate treatment can largely reduce
the chance of getting a stroke.

Central blood pressure parameters

The device is designed to assess central blood pressure parameters (optional).
Central blood pressure is the pressure in the ascending aorta, the largest artery that originates
from the left ventricular of the heart and from where oxygen is distributed to all parts of the body
through the systemic circulation. Central Systolic Blood Pressure and Central Pulse Pressure
provided by this monitor are determined directly through pulse volume plethysmography
(PVP) waveform analysis. Central Diastolic Blood Pressure by this monitor is calculated by
subtraction of Central Systolic Blood Pressure and Central Pulse Pressure.

How is central blood pressure measured?

The device measures brachial systolic and diastolic blood pressure as usual. However, where
the cuff normally totally deflates after the blood pressure measurement, the cuff now stops
deflating at approximately 60 mmHg cuff pressure to keep a stable pressure on the brachial
artery for approximately 10 seconds which is needed to acquire brachial pulse volume
plethysmography (PVP) waveforms (pulse volume recording). During these 10 seconds
approximately 10 PVP waveforms are recorded from which one average PVP waveform is
determined and analyzed. From the average PVP waveform, some characteristic points
(parameters) are identified that are directly related to arterial compliance (stiffness) and wave
reflections. With these parameters and previously measured peripheral (regular) blood
pressure the central systolic blood pressure value and the central pulse pressure value are
1
then determined
.
The time that is needed to determine the central blood pressure value may vary among
patients; i.e. with faster heart rate, less time is required for collecting the number of required
PVP waveforms. It is very important to keep the arm still during the time the PVP waveforms
are collected.
12