Mt Elizabeth Hospital, 3 Mount Elizabeth #14-13, Mt Elizabeth Medical Centre, S228510
Electrocardiogram (ECG or EKG) at Cadence Heart

Ambulatory Blood Pressure (ABP) Monitoring

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What is ABP monitoring?

Ambulatory Blood Pressure monitoring is the non-invasive, 24-hour monitoring of a patient’s systolic and diastolic blood pressure. 

  • Systolic blood pressure refers to the pressure in the arteries when your heart contracts.
  • Diastolic blood pressure refers to the pressure in arteries when your heart relaxes.

If the measurement is 120 systolic and 80 diastolic, the monitor should display “120/80 mmHg”.

As its name suggests, patients are required to wear a belt or strap with a blood pressure monitor. This is attached to a cuff placed on the patient’s non-dominant arm.

The device takes blood pressure measurements for a 24-hour period while the patient goes about their daily activities. These measurements are then collected, processed and evaluated by the doctor.

What does ABP monitoring detect?

ABP monitoring can detect:

  • High blood pressure (Hypertension)
  • Low blood pressure (Hypotension)
  • The potential for cardiovascular events, mortality, or end-organ disease
  • The effects of drugs on blood pressure
  • The potential for worsening of renal issues in patients with chronic kidney disease (CKD), or the potential for cardiovascular events in patients with CKD

Why is ABP monitoring important?

ABP allows your cardiologist to get a more accurate picture of your blood pressure patterns at different times of the day. 

For example, it shows your cardiologist how your blood pressure dips at night. Additionally, a one-off blood pressure measurement would not be enough to determine the type of hypertension you may have or to help discern whether certain treatments or medications are working.

Why is measuring your blood pressure important?

Measuring your blood pressure is a good indicator of whether you suffer from hypertension or hypotension. 

Hypertension

Most underlying conditions related to blood pressure often go undiscovered until it is too late. An example would be hypertension, the “silent killer”. Hypertension refers to high blood pressure.

“SILENT”

  • Hypertension may show no symptoms until the patient has a stroke or heart attack.
  • Symptoms such as headaches or giddiness only surface in rarer, severe cases of hypertension. 
    • Even then, such symptoms are often inconclusive and may be mistaken for signs of other conditions, allowing hypertension to go unnoticed.

“KILLER”

  • Hypertension increases the risk of getting cardiovascular events like, coronary artery disease, heart attack and heart rhythm disorders like atrial fibrillation.  
    • Hypertension causes tears in arterial walls which heal to form scar tissue. This allows the easier build-up of cholesterol and fat in arteries. 
    • That build-up causes arterial walls to be narrower and less elastic, forcing the heart to work harder to pump blood to the rest of the body 
    • Higher workload leads to thicker heart muscles, enlarging the heart. 
    • The heart becomes unable to pump blood that well, resulting in heart failure.
  • Hypertension also causes end-organ disease or organ failure in the heart, brain and kidney.
    • Organ failure occurs when blood vessels leading to or in those organs, harden or become damaged due to chronic high blood pressure. T

Only through blood pressure monitoring  can hypertension be reliably diagnosed. 

Hypotension

Conversely, hypotension refers to low blood pressure, or hypotension. 

  • Asymptomatic hypotension does not impact a person's life and is not a cause for concern
  • Symptomatic hypotension can cause dizziness, fatigue, nausea, fainting spells and even depression.
    • Without fainting spells, the rest of the symptoms will be insufficient to diagnose someone with hypotension. 
    • Without a diagnosis, symptoms will persist even after taking over-the-counter prescriptions, which decreases the quality of life one has.

Hypotension is most reliably diagnosed by measuring blood pressure as well. 

Hence, patients need to undergo blood pressure testing to correctly identify any underlying conditions such as hypertension and hypotension. This will help patients receive the proper treatment they need to get better and live life to the fullest.

What is the difference between Ambulatory, Home and Office Blood Pressure Monitoring?

Doctor taking patient's blood pressure

The table below shows a quick comparison between Ambulatory, Home and Office Blood Pressure monitoring.

Types of monitoringMethodologyAdvantagesWeaknesses
Ambulatory Blood Pressure (ABP) MonitoringBlood pressure is measured at regular intervals over 24 hoursABP can detect  Variability in blood pressure at night, which indicates risk for cardiovascular disease.
ABP is also able to detect: Whitecoat hypertension Masked hypertension, Blood pressure variability  Hypotension Organ damage
ABP is  More inconvenient for the patient compared to HBP and OBP monitoring as the device needs to be worn for 24 hours. 
The most costly
Home Blood Pressure (HBP) MonitoringThe blood pressure is recorded by the patient themselves, once in the morning and the evening for 4-7 days. Each recording should contain two consecutive blood pressure measurements, at least 1 minute apart, with the patient seated.HBPM can detect  Whitecoat hypertension Masked hypertension, Blood pressure variability Organ damage Hypotension
HBP monitoring is less costly than ABP monitoring.
HBPM is  unable to detect changes in blood pressure at night.
less accuracy on average, as the patient has to take the measurements themselves. 
Office Blood Pressure (OBP) Monitoring Patients visit the doctor to get their blood pressure taken by an automated or non-automated oscillometric sphygmomanometer.OBP monitoring can detect: Hypotension Hypertension Organ damage 

OBP monitoring is less costly than both HBP and ABP monitoring as well as more convenient for the patient
OBP monitoring is Unable to detect Whitecoat hypertension, masked hypertension.
  A less accurate predictor of cardiovascular events and other target organ damage. 

This will affect the effectiveness of treatments given as well as the accuracy of diagnosis.  

As seen from the table, ABP and HBP monitoring provide more prognostic value than OBP as they are better able to predict how likely conditions, such as cardiovascular disease, will occur. Both HBP and ABP monitoring are also more accurate in detecting target organ damage as compared to OBP monitoring.

Which is better, HBP or ABP monitoring?

Guy taking his own blood pressure

There is no “better” means of measuring blood pressure. However, one may be more suited to diagnose your condition than the other. 

HBP monitoring measures blood pressure variability twice a day, while ABP monitoring measures blood pressure variability of the patient for 24 hours, including at night. Studies have shown that nighttime measuring of blood pressure variability provides a more accurate prediction of cardiovascular events occurring compared to daytime measuring. Thus, using ABP monitoring leads to a more accurate diagnosis and medication being provided in more effective dosages than HBP monitoring. 

Hence, while all three can detect similar issues, ABP and HBP monitoring are more comprehensive than OBP monitoring, with Ambulatory Blood Pressure monitoring being the most accurate predictor of future heart issues.

What is Whitecoat and Masked Hypertension?

Two notable subtypes of hypertension include: 

Whitecoat hypertension

When a patient is in the clinic, their blood pressure readings may be higher as compared to when they are in other settings, leading to inaccurate diagnosis of hypertension. 

Masked hypertension

Conversely, when the patient is in the clinic,  they may not have high blood pressure reading. However, when they are out of the clinic, their blood pressure is high as a result of stress at work or sleep apnea. This may lead to a misdiagnosis of no hypertension, when there in fact, is. 

These two subtypes are best detected using Ambulatory Blood Pressure Monitoring as compared to Home Blood Pressure and Office Blood Pressure monitoring.

What do the Blood Pressure readings mean?

During the test, some might be puzzled over the numbers appearing on the blood pressure monitor and how to interpret them. 

For adults (aged 18 years and older), hypertension occurs when the systolic blood pressure is >140 mmHg or when diastolic blood pressure is >90 mmHg. 

Hypotension, on the other hand, occurs when the systolic blood pressure is less than 100/60 mmHg.

The larger number or the number at a higher position usually is the systolic pressure, while the number below is usually the diastolic blood pressure. 

For the ranges of blood pressure (BP) relating to specific stages of hypertension, please refer to the chart below:

Categories for Blood Pressure Levels in Adults (Aged 18 and older)


Blood Pressure (BP)  Level (mmHg)
CategorySystolic
Diastolic




Normal BP<120and<80
High-Normal BP130or80-89
High BP>140or>90
Stage 1 Hypertension140-159or90-99
Stage 2 Hypertension160or100
Isolated Systolic Hypertension*>140and<90


Data is taken from Healthhub Singapore
*When the systolic and diastolic BP fall under different categories, the higher categories apply

After interpreting the BP readings, this is what you can expect from your doctor:

Normal BP

No treatment necessary. However, it is still important you maintain your blood pressure, especially as you age

High-normal BP

This indicates you may be at risk of developing hypertension. Medication might not be necessary but the doctor might advise you on lifestyle changes to help lower your blood pressure

Hypertensive

Any reading above Stage 1 Hypertension means you are hypertensive. Your doctor may recommend medication and lifestyle changes to help lower blood pressure

Who is ABP monitoring for?

Your cardiologist will generally recommend Ambulatory Blood Pressure monitoring if you have: 

  • Known hypertension
  • A “high-normal” blood pressure
  • Difficulty controlling blood pressure with medication.
  • Blood pressure changes due to other drugs.
  • Changes in prescription medications that may impact blood pressure
  • Fainting episodes or hypotension

How can I prepare for ABP monitoring?

You may want to shower before ABP monitoring as it is best to avoid water during this time, and there is no need to fast. In fact, you should eat as you normally would. Other steps you can take are to:

  • Wear short-sleeved, loose-fitting clothes 
  • Continue to take prescribed medications unless otherwise instructed by your cardiologist

What can I expect during ABP monitoring?

To get a more accurate reading:

  • Try to be seated and keep the blood pressure cuff at heart level when the machine starts to measure your blood pressure.
  • Keep your arm straight when the device is taking blood pressure measurements.
  • Make sure there are no kinks or twists in the tube between the cuff and machine.
  • Take note of significant daily activities like when waking up, sleeping, taking medication and light exercise.

What should I avoid during an ABP monitoring period?

  • Water-based activities, including showering
  • Removing the device at any point in time
  • Dropping the devices
  • Strenuous activity
  • Operating heavy machinery
  • Using electric blankets to sleep

Some slight discomfort may be experienced when the blood pressure cuff inflates. You may also experience slight itchiness under the cuff. If this discomfort becomes intolerable, do inform your cardiologist instead of tampering with or removing the device.

Summary

Happy couple

Hopefully, we’ve helped you better understand ambulatory blood pressure monitoring. Decisions regarding your medical treatment should not be done alone, so if you have any needs or concerns, please contact your cardiologist for further discussion. 

Dr Devinder Singh

Senior Consultant Cardiologist &
Cardiac Electrophysiologist

Dr Devinder Singh is the Medical Director of Cadence Heart Centre. He is an experienced Senior Consultant Cardiologist & Cardiac Electrophysiologist with over 20 years of clinical experience.

His expertise lies in clinical cardiology, cardiac rhythm disorders (arrhythmia), cardiac pacing (including cardiac resynchronisation therapy) and cardiac magnetic resonance imaging. He performs electrophysiology studies and radiofrequency ablation of cardiac arrhythmias, and is well versed in pacemaker and defibrillator insertions.

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