Did you know?


Your heart is about the size of two fists and weighs 10 ounces, or slightly less than a can of soda. Each valve—the parts that open and close to allow blood to flow in and out—is about the size of a half-dollar.

Dr Johan Janssen MD, PhD, FRACP, FCSANZ

  • Fun Facts
    Dr Janssen’s nickname is, ‘Flying Dutchman’.
  • Languages spoken
    English, Dutch, French, German

Dr Janssen received his medical degree from Maastricht University in 1980 and became a cardiologist under Professor Hein Wellens in 1985. He specialised in Interventional Cardiology (stenting) and Electrophysiology (treating abnormal rhythms).

Later, Dr Janssen then worked as an associate professor in cardiology in the Netherlands, both in Maastricht and Rotterdam. After working in the Kingdom of Saudi Arabia, he moved with his family to Perth, Western Australia where he joined Western Cardiology as a partner in 2005.

Dr Janssen consults at St John of God Midland Public Hospital as well as providing consultations and inpatient care at St John of God Subiaco Hospital. He also runs weekly clinics in Kalgoorlie and monthly clinics in Geraldton. He provides teaching for medical students in rural areas (Rural Medical School UWA and Notre Dame) as well as at SJG Subiaco Hospital. He is based in Western Cardiology in Joondalup.

Understanding your heart

Six Important Things About Your Heart

Adult heart beats about 10,000 times each day 01.

Do the math, and that’s at least about one beat per second, or 60 to 100 times per minute, according to American Heart Association.

Age and fitness level affect your heart rate 02.

Generally, as children grow or adults get fitter, the heart rates gets slower.

Heart disease isn’t only the number one killer of men, it’s also the top killer of women 03.

Your heart doesn’t care if you’re from Mars or Venus.

Dr Janssens Consulting Services

04. Want to know how big your heart is? Make a fist.

Heart size depends on the size of the person as well as the condition of their heart. Generally speaking, a healthy heart is about the size of the person’s fist.

05. Your heart rate drops while you sleep.

At night, it’s common for heart rates to drop below 60bpm.

06. Heart attack symptoms are different for men and women.

Although heart disease is an equal opportunity killer, symptoms of heart attack show up differently in men versus women.