60 Fun Facts About Heart

How many chambers does the human heart have?

The upper two are the atria and the lower two the ventricles; fish get by with two and most reptiles with three.

What are the two upper chambers of the heart called?

The word is Latin for an entrance hall, which is roughly what they are: blood arrives there before being passed down to the pumping chambers below.

Roughly how much does an adult human heart weigh?

That is about the weight of a large orange, and it is famously about the size of the owner's clenched fist.

What is the normal range for an adult's resting heart rate?

Fitness pushes the number down: an ultra-trained endurance athlete can tick over at 37 or 38 beats a minute.

Which structure acts as the heart's own natural pacemaker, setting the normal sinus rhythm?

It sits in the wall of the right atrium and would fire about 100 times a minute if the nervous system did not rein it in to a resting 70 or so.

Which chamber of the heart has by far the thickest muscular wall?

The right side only has to push blood next door to the lungs; the left has to drive it out to the toes and back.

What is the name of the sac that surrounds the heart?

Inflammation of it is pericarditis, which classically produces chest pain that eases when the patient sits up and leans forward.

The wall of muscle that separates the heart's two lower pumping chambers from each other is called what?

A hole in it at birth is a ventricular septal defect, the most common congenital heart defect and one that often closes on its own.

The myocardium, the middle layer of the heart wall, is made of which type of tissue?

It is striped like the muscle in your arm but works without conscious control like the muscle in your gut, a combination found nowhere else in the body.

Which of these sits between the right atrium and the right ventricle?

As the name says it has three flaps; its partner on the left side has only two, which is why that one is also called the bicuspid valve.

Because it has two cusps, the mitral valve is also known by what name?

The name mitral comes from its resemblance to a bishop's mitre.

Roughly how long after conception does the embryonic human heart begin to beat?

That is around five weeks after the last menstrual period, often before the pregnancy has been confirmed.

Which parasympathetic nerve, named from the Latin for wandering, acts to slow the heart rate?

Its name means wandering, and stimulating it hard enough (a sudden fright, straining, or bearing down) can drop the heart rate enough to make someone faint.

What is a resting adult heart's average cardiac output, i.e. blood pumped per minute?

That works out at roughly 7,000 litres a day, enough to fill a small road tanker, from an organ the size of a fist.

What is the largest artery in the human body, carrying blood out of the heart's main pumping chamber?

In an adult it is roughly the diameter of a garden hose where it leaves the heart.

The 'lub' of the heart's 'lub-dub' sound is caused by the closing of which pair?

The 'dub' that follows is the aortic and pulmonary valves snapping shut as the ventricles finish contracting.

A heart murmur is a sound produced by what?

Many murmurs are harmless, especially in children, but some point to a leaking or narrowed valve.

The stethoscope was invented in 1816 by René Laennec in which country?

The first one was a simple wooden tube; Laennec came up with it because he was uncomfortable pressing his ear directly to a female patient's chest.

Which English physician first fully described blood circulation in his 1628 book De Motu Cordis?

The book ran to just 72 pages and was dedicated to King Charles I, whose personal physician he was.

Which Dutch physiologist's 1903 string galvanometer made precise ECGs possible, winning a 1924 Nobel?

The letters P, Q, R, S and T that label the waves on every ECG trace today come from his notation.

On an ECG trace, the QRS complex represents the electrical depolarization of which part of the heart?

The smaller P wave before it is the atria firing, and the T wave after it is the ventricles resetting for the next beat.

In 1929 Werner Forssmann performed the first human cardiac catheterization. On whom?

He threaded a tube up a vein in his own forearm into his heart, walked to the X-ray room to prove it, was sacked for it, and shared a Nobel Prize for it in 1956.

In which city did Christiaan Barnard perform the first human heart transplant in 1967?

The patient, grocer Louis Washkansky, lived 18 days and died of pneumonia; Barnard's second patient survived more than 18 months.

At which university's hospital did Norman Shumway perform the first US adult heart transplant in 1968?

Shumway had spent a decade developing the technique in dogs; Barnard, who had studied his methods, beat him to a human patient by a month.

Roughly how many heart transplants are performed worldwide each year?

The number is limited by donors, not demand; the 1983 arrival of the anti-rejection drug cyclosporine is what turned the operation from an experiment into routine care.

The first fully implantable pacemaker was fitted in October 1958 in which country?

The patient, Arne Larsson, went through 26 pacemakers and died in 2001 aged 86, outliving both the surgeon and the inventor.

What was the permanent artificial heart Barney Clark received in December 1982 called?

Clark lived 112 days tethered to a 400-pound pneumatic drive console.

In a coronary bypass operation, which vessel from the leg is most commonly harvested to use as the graft?

Arteries such as the internal mammary stay open longer, but the leg vein is long, easy to reach and the leg manages without it.

Cardiovascular disease is the top killer worldwide. Roughly how many deaths did it cause in 2015?

That was just under a third of all deaths on Earth that year, and it is estimated that up to 90 percent of cardiovascular disease is preventable.

Which is the only continent where cardiovascular disease is NOT the leading cause of death?

Infectious diseases still claim more lives there, though heart disease is climbing fast as diets and cities change.

A heart attack is known medically by what term?

Infarction means tissue death from lost blood supply, and the muscle downstream of a blocked artery starts dying within minutes.

Which over-the-counter drug is recommended for a suspected heart attack because it stops platelets clumping?

Its active ingredient descends from willow bark, used as a remedy for at least 2,400 years before Bayer put the name on it in 1899.

Which blood test marker is considered the best indicator that heart muscle has been damaged?

It is a protein that leaks out of dying heart cells, and modern high-sensitivity tests can pick it up within a couple of hours of a heart attack.

Compared with men, women having a heart attack more often present without which classic symptom?

Fatigue, jaw or neck discomfort and nausea are more common in women, which is one reason their heart attacks are more often missed.

Which British physician first clinically described angina in 1768?

Nitroglycerin, the same compound used in dynamite, has been slipped under the tongue to relieve it since 1879.

Roughly what percentage of people who suffer a cardiac arrest outside hospital survive?

Survival roughly doubles when a bystander starts CPR immediately, and every minute without a shock cuts the odds further.

Which two chaotic heart rhythms are most commonly recorded at the moment of a cardiac arrest?

These are the 'shockable' rhythms a defibrillator is designed to reset; a flatline, despite what television shows, is not.

Under the 2020 CPR guidelines, at what rate should an adult's chest be pressed?

Compressions should also be 5 to 6 centimetres deep, which is harder work than most people expect and often cracks a rib.

Which Bee Gees song does the American Heart Association suggest to keep time for CPR?

It runs at 104 beats per minute; Queen's 'Another One Bites the Dust' has the right tempo too, but a worse title for the occasion.

In standard CPR, what is the recommended ratio of chest compressions to rescue breaths?

Untrained bystanders are now told to skip the breaths entirely and just keep pressing, since interruptions cost more than the extra oxygen gains.

Which two blood-pressure readings define stage 2 hypertension?

The first number is the pressure while the heart squeezes and the second while it rests between beats; the cuff to measure it was invented by Scipione Riva-Rocci in 1896.

Which cholesterol particle is popularly called 'bad cholesterol' because it deposits in artery walls?

About 80 percent of the cholesterol in your body is made by your own liver and intestines rather than eaten.

How much moderate aerobic activity per week does the World Health Organization recommend for adults?

That is a brisk 30-minute walk five days a week, or 75 minutes of something vigorous enough to make talking hard.

What is the most common serious abnormal heart rhythm, affecting over 33 million people worldwide?

The upper chambers quiver instead of beating, blood pools and clots, and a clot that escapes to the brain causes a stroke, which is why patients are put on blood thinners.

In the stroke-recognition mnemonic FAST, what does the letter T stand for?

The other letters are face drooping, arm weakness and speech difficulty; about 87 percent of strokes are caused by a blockage rather than a bleed.

Which animal has the largest heart ever recorded, one specimen weighing about 180 kilograms?

On a deep dive its heart rate can fall to two beats a minute, then climb to 37 when it surfaces to breathe.

How many hearts does an octopus have?

One pumps blood round the body and two smaller ones push it through the gills; the blood itself is blue because it carries oxygen with copper rather than iron.

Roughly how much blood pressure must a giraffe's heart generate compared with a human's, to reach its brain?

The heart doing that work weighs around 11 kilograms and is about 60 centimetres long.

The fastest heart rate ever measured in a bird, 1,260 beats a minute, was recorded in which group?

At night the same bird can drop into torpor and let its heart rate fall to a small fraction of that to save energy.

On which date each year does the World Heart Federation hold World Heart Day?

In the United States, February is designated American Heart Month by federal law and marked with a national 'wear red' day.

The first known, if disputed, romantic heart symbol appears in a 1250s manuscript of which French romance?

Sceptics point out that the object the kneeling lover holds up may simply be a pear, which is what the poem is named after.

Roughly how many times does a human heart beat over an average lifetime?

The everyday shortcut for your maximum safe heart rate, 220 minus your age, was devised in 1970 and is famously rough for anyone over 40.

In the fetal heart, what is the opening between the atria that closes soon after birth called?

Within seconds after birth a flap called the septum primum closes it, leaving a depression called the fossa ovalis.

Which specialised fibres carry the electrical signal through the ventricles to the heart muscle?

The signal runs from the AV node down the bundle of His and its branches before reaching them.

Which 13th-century physician first described pulmonary circulation, contradicting Galen?

His 1242 commentary on Avicenna's Canon said blood passed through the lungs rather than through pores in the septum.

Which Japanese researcher discovered the atrioventricular node, publishing in 1906?

His find prompted Arthur Keith and Martin Flack to hunt for similar tissue, and they found the sinoatrial node months later.

Ancient Egyptians believed the heart was weighed against the feather of which goddess?

A heart heavier than the feather was devoured by the monster Ammit; a balanced scale meant a just life.

Adult amphibians and most reptiles have a heart with how many chambers?

Two atria feed a single ventricle, so blood for the lungs and body mixes to some degree.

Which people practised heart-extraction as their most common form of human sacrifice?

They believed the heart was both the seat of the individual and a fragment of the Sun's heat.

Roughly how long ago did the heart first evolve, in fish?

A fish heart is usually described as two-chambered, one atrium receiving blood and one ventricle pumping it.