Blood Pressure & Cardiovascular Physiology

Australia has made real progress in cardiovascular disease, but heart and blood-vessel conditions still create a major burden. Blood pressure is one of the most important measurements in that story. The useful question is not only 'Is the number high?' but also 'What physiological pattern is producing it - and what else should be measured?'

Primary source: Australian Institute of Health and Welfare, Australia's health 2026.

The Australian picture

Cardiovascular disease is a broad term covering conditions of the heart and blood vessels, including coronary heart disease, stroke, heart failure, atrial fibrillation and peripheral arterial disease. In Australia's health 2026, cardiovascular diseases were the fourth-largest disease group by burden, accounting for 12% of total disease burden in 2024.[1]

There has also been substantial progress. Coronary heart disease deaths fell by 18% between 2015 and 2024, from 19,926 to 16,326. AIHW attributes broader declines in cardiovascular deaths to improvements in detection, prevention and care, together with declines in tobacco smoking, high blood pressure and high cholesterol.[1]

The lesson is important for Physiology First: risk does not sit in one number. AIHW points to Heart Health Checks and the earlier identification and management of high blood pressure, cholesterol, blood glucose and smoking. In 2024-25, almost 113 million prescriptions for cardiovascular medicines were dispensed through the PBS - 34% of all PBS prescriptions.[1]

Blood pressure is a measurement, not a diagnosis of cause

Blood pressure describes the pressure of circulating blood against the walls of the arteries. It rises and falls naturally through the day with activity, posture, stress and other influences. High blood pressure becomes a concern when the pressure is persistently elevated, because it increases the risk of heart attack, stroke and other cardiovascular problems.[2]

Most people with high blood pressure do not have one single identifiable cause. Healthdirect describes this as essential or primary hypertension. In a smaller group, high blood pressure is secondary to an identifiable condition or exposure such as kidney disease, narrowing of the arteries to the kidneys, certain hormonal conditions, medicines or drugs, sleep apnoea, or complications of pregnancy.[3]

That distinction matters. Treating the blood pressure number can be essential and lifesaving, but understanding the surrounding physiology can help identify what else needs attention.

What physiology can sit behind a high reading?

1. Blood-vessel tone and stiffness. Arteries can be more constricted or less elastic. Ageing, smoking, metabolic disease and vascular damage can all affect how easily blood moves through the circulation. The tighter or stiffer the vascular system, the more pressure the heart may need to generate.

2. Kidney function, sodium and fluid balance. The kidneys regulate salt, water and several hormones involved in blood-pressure control. Kidney Health Australia emphasises that the relationship runs both ways: high blood pressure can damage the kidneys, and kidney damage can in turn raise blood pressure.[4]

3. The renin-angiotensin-aldosterone system. This hormone system helps regulate blood-vessel constriction, sodium retention and circulating volume. Several common blood-pressure medicines act on this pathway. If the system is overactive because of an underlying condition, pressure can remain elevated.

4. Sympathetic nervous-system drive. Stress, pain, poor sleep, stimulants and other factors can increase sympathetic activity - the "fight or flight" side of the nervous system - raising heart rate and vascular tone. A temporary rise is normal; persistent activation may contribute to a higher pressure pattern.

5. Metabolic health and body composition. Excess abdominal fat, diabetes, inactivity and related metabolic changes frequently cluster with high blood pressure. These factors do not explain every case, but they can form part of the same cardiovascular-risk pattern.[1][5]

6. Sleep-disordered breathing. Untreated obstructive sleep apnoea is associated with high blood pressure and a higher risk of arrhythmias, coronary heart disease, heart failure and stroke. Snoring, witnessed breathing pauses, morning headaches or marked daytime sleepiness are reasons to discuss sleep assessment with a health professional.[6]

What is worth measuring?

The aim is not to order every test available. It is to confirm the blood-pressure pattern and then build enough context to understand cardiovascular and kidney risk. Depending on the person's history and clinical assessment, useful information may include:

Measure it properly before interpreting it

Blood pressure is unusually sensitive to how it is measured. The Heart Foundation recommends sitting quietly for five minutes, keeping the back and arm supported, placing both feet flat on the floor and taking two readings about a minute apart. Home monitoring can provide a better picture than one isolated clinic result, and 24-hour ambulatory monitoring can show how pressure changes across the day and night.[2][7]

This is a core Physiology First principle: poor measurement creates poor conclusions. Before asking why a number is high, first make sure the number is real and reproducible.

Treat the whole risk pattern, not just the number

The Heart Foundation's Heart Health Check is built around this idea. It combines blood pressure with cholesterol, blood sugar, smoking status, medicines, medical history and family history to estimate cardiovascular risk and guide a management plan.[5]

Blood-pressure medicine may be an important part of that plan. A Physiology First approach is not an argument against medication and should never be used to stop or alter prescribed treatment without medical advice. The better question is whether the treatment plan is controlling the pressure while also addressing the person's broader cardiovascular, kidney, metabolic, sleep and lifestyle risks.

Questions worth asking

• Is my blood pressure consistently high, or have we confirmed it with home or 24-hour measurements?
• What was my blood pressure before treatment, and what is it now?
• Have my kidney function, sodium and potassium been checked?
• Do my glucose, cholesterol, waist measurement and blood pressure point to a broader metabolic-risk pattern?
• Do I have symptoms or risk factors for obstructive sleep apnoea?
• Could any medicines, anti-inflammatory drugs, stimulants, alcohol, smoking/vaping or supplements be contributing?
• Is there anything in my age, family history, kidney history or pattern of hypertension that suggests a secondary cause should be investigated?
• What are we going to re-measure, and when, to know whether the plan is working?

When professional assessment matters

Persistently high blood pressure deserves medical assessment even when a person feels well, because hypertension is often silent. Very high readings, chest pain, sudden shortness of breath, neurological symptoms, fainting or other acute symptoms require prompt medical attention. Investigation is particularly important when blood pressure is difficult to control, appears unusually early, is accompanied by kidney abnormalities or low potassium, or there are symptoms suggesting sleep apnoea or another secondary cause.[3][4]

The Physiology First takeaway

Blood pressure is one of the most useful measurements in preventive health - but it is still a measurement. It can reflect vascular tone, kidney and fluid balance, nervous-system activity, metabolic health, sleep, ageing, medicines and, in some people, an identifiable secondary condition.

KNOW → MEASURE → UNDERSTAND → CONNECT → QUESTION → OPTIMISE → RE-MEASURE

That is the role of the Physiology First lens: confirm the measurement, connect it to the wider physiology, treat risk appropriately and then measure again. The purpose is not to replace medical care, but to make the questions around that care better.

BETTER HEALTH THROUGH BETTER FOUNDATIONS

All articles