High temperatures and chronic diseases: The silent risks of summer for the heart and brain

Summer brings with it longer days, sun, sea and relaxation – but also specific health challenges, especially for people living with chronic diseases. As temperatures rise, so does the strain on the heart, blood vessels and the entire circulatory system. Heart attacks and strokes are more common during heat waves, and the number of hospitalizations for chronic patients increases significantly.

What happens to the body in extreme heat?

When the outside temperature is high, the body activates cooling mechanisms to maintain the internal temperature around 37 °C. A key role in this is played by blood vessels , which dilate (a process known as vasodilation ) to allow greater blood flow to the skin and increased evaporation of sweat.

This physiological response has a number of consequences, especially in chronic patients:

• Lowering blood pressure : Dilation of blood vessels leads to a decrease in peripheral resistance, which can lower arterial pressure. In people who are already taking antihypertensive medications or have a tendency to hypotension, this can cause weakness, dizziness, and even collapse.
• Dehydration and blood thickening : Sweating causes loss of water and electrolytes. If fluid intake is not adequately replaced, blood becomes thicker and viscosity increases, which increases the risk of thrombosis – the formation of clots that can block blood vessels in the brain (stroke) or heart (heart attack).
• Fluid retention in the lower extremities : Dilation of the veins and poor blood return from the legs lead to swelling of the legs and ankles, which is a common summer complaint. In people with heart failure, this can be a sign of worsening.
• Additional strain on the heart : Although blood pressure may drop, the heart must work harder to ensure blood flow to vital organs. This can cause deterioration of heart function, the appearance of arrhythmias, or recurrent angina.

Why is the risk of heart attack and stroke increasing?

In the summer, especially during heat waves, the number of hospital admissions due to cardiovascular incidents increases . Elderly people, those with already diagnosed heart or cerebrovascular diseases, and patients with diabetes and kidney disease are particularly at risk.

Heart attack (myocardial infarction)

It occurs when a clot forms in one of the coronary arteries and cuts off blood flow to the heart muscle. Heat, thick blood, and dehydration increase the chance of such clots. Typical symptoms include:

• severe pain or pressure in the chest,
• sweating,
• difficulty breathing,
• nausea or dizziness.

Stroke (cerebrovascular accident)

It is most often caused by a blockage of an artery in the brain by a clot (ischemic stroke), less commonly by a ruptured blood vessel (hemorrhagic stroke). Heat increases the risk through a combination of dehydration, increased blood viscosity, and changes in blood pressure. Symptoms include:

• sudden weakness of the face, arm or leg (especially on one side),
• speech disorder,
• confusion,
• loss of balance or vision.

Can hyperbaric oxygenation play a preventive role?

At our clinic, we use hyperbaric oxygen therapy (HBOT) as part of an integrative approach to cardiovascular diseases and neurological rehabilitation. HBOT involves inhaling 100% oxygen in a hyperbaric chamber at elevated pressure, which allows for significantly higher oxygen saturation in the bloodstream and better tissue oxygenation.

Although not a primary means of preventing heart attack or stroke, HBOT can contribute to improving microcirculation , reducing oxidative stress and inflammation, which has a positive long-term effect in people with increased cardiovascular risk.

Several studies confirm these benefits:

• Thom SR et al., published in the Journal of Applied Physiology , indicates anti-inflammatory and endothelial benefits of HBOT in individuals with vascular dysfunction.
  https://journals.physiology.org/doi/full/10.1152/japplphysiol.00248.2005
• Heyboer M et al., ( Undersea and Hyperbaric Medicine Journal ), highlight the prevention of oxidative tissue damage and stimulation of vascular angiogenesis in stroke survivors.
  https://www.uhms.org/resources/research.html
• Boussi-Gross R et al., in an Israeli study, report improvements in cognitive function and cerebral perfusion in patients who have had a stroke.
  https://pubmed.ncbi.nlm.nih.gov/23379675/

It is important to emphasize: HBOT is not used acutely in the event of a heart attack or stroke, but rather as part of ongoing care and prevention of complications, with prior medical assessment.

Preventive measures: how to reduce risk during heatwaves

Although we cannot avoid heat, it is possible to reduce its harmful effects on the heart and blood vessels. It is crucial to maintain adequate hydration , avoid exposure to the sun during the hottest part of the day (11 am–5 pm), wear light and breathable clothing, and stay in cool areas whenever possible. People taking medication for blood pressure, heart disease, or blood clotting should regularly measure their blood pressure and pulse , and consult their doctor in a timely manner about possible adjustments to their therapy. If you notice symptoms such as unusual weakness, headache, chest pressure, slurred speech, or facial numbness, you should seek medical attention immediately . In an integrative approach to prevention, supportive therapy such as hyperbaric oxygenation may also be considered for individual patients to strengthen microcirculation and blood vessel resistance.

In conditions of increasingly frequent heat waves, prevention is no longer a choice, but an everyday necessity.

Note: This content is for informational purposes only and does not constitute medical advice or replace consultation with a professional healthcare professional.