Dr Tan Ju Le, Consultant, Department of Cardiology shared with The New Paper on dextrocardia, a rare heart condition, where the heart is on the right side of the chest instead of the left.
When teacher Cheng Boon Wah, 33, goes for check-ups, doctors invariably tell him everything is fine after putting their stethoscopes to the left side of his chest.
But, after he tells them to listen to the right side of his chest, heart murmurs can be detected.
And when electrocardiograms are done on him, he tells nurses to place the devices on the right side of his chest.
That's because Mr Cheng's heart is found on the right - or rather, wrong - side of his body.
Mr Cheng suffers from a rare congenital condition called dextrocardia, where the heart is in the right side of the chest, instead of the left.
Dr Tan Ju Le, a consultant at the National Heart Centre Singapore (NHCS), where Mr Cheng is a patient, says it is estimated the condition affects 1 in 12,000 pregnancies worldwide.
At the NHCS, there are eight dextrocardia cases, including Mr Cheng.
It is not known what causes the condition.
Dr Tan said the condition is usually detected through clinical examinations or chest X-rays, and it is usually accompanied by other heart defects like holes in the heart, blocked arteries and small or absent heart chambers.
In Mr Cheng's case, his heart has only one pumping chamber instead of the usual two. This causes insufficient blood flow to the lungs and inadequate oxygen supply to the body.
He said: 'Because of this, I can't engage in vigorous exercises. I can jog but once I go faster, I start panting.'
Mr Cheng has had three operations on his heart, with the most recent one done to seal off an enlarged atrium from the pumping chamber as it could cause a turbulent flow of blood and blood clots.
The other two operations were done to replace one of the atria with a conduit to reduce the mixing of oxygenated and de-oxygenated blood, and to improve the efficiency of blood flow through the arteries.
Mr Cheng's condition got him exempted from physical education lessons in school, and National Service. But he was no sluggard.
'I still took part in games like basketball and did light jogging. I kind of felt left out because I like sports like cycling, basketball and street soccer.'
He needs to go for check-ups at the NHC every three months to check his blood flow, heart and liver functions and the effectiveness of the drugs he takes.
Said Mr Cheng, who is single: 'My body tends to store water as my heart doesn't pump as well so I have to take two diuretics to make me urinate more.
'Otherwise, my legs and liver will become bloated due to water retention. It's not painful but it's difficult to move around because you feel quite stiff in the region.
'My liver has to be checked because long-term medication is generally not good for the liver.'
Going for dental check-ups also requires him to be cautious as dentists have to give him antibiotics to prevent infections.
Mr Cheng always goes to the National Dental Centre (NDC), which is a stone's throw from the NHC, to clean his teeth.
He explained: 'Scaling usually results in bleeding gums and cardiac patients are more prone to infections as their immunity is lower. Going to NDC to clean my teeth is a better option because if there are any problems, the NHC doctors can always come by.'
Mr Cheng, the eldest of three children, claims he has never grumbled, though he is the only one in his family who has not enjoyed good health. None of his relatives have heart problems, he said.
He said: 'I have the chance to live a normal life. I felt teaching was my calling and I've never looked back.
'Of course, there are times when I wondered what I could have done if I had a normal heart. If I had a regular heart, I'd be a pilot because I'd love the experience of flying a plane.'
First detected in 17th century
The first known case of a right-side heart in a man was reported in 1606 by Italian anatomist Girolamo Fabrici.
This was followed by a case recorded in 1643 by Italian surgeon Marco Severino.
Two more reports were lodged in the same century - one of which occurred in the French Queen, Marie de Medici (1573-1642).
In 1650, the congenital problem was found in a man executed for the murder of the Duke of Beaufort.
Until the 1800s, when medical equipment became more advanced, dextrocardia was usually discovered only during autopsies.
Today, with an array of X-rays, electrocardiogram and angiography, detecting the heart's position and any associated cardiac defects has been made relatively simple and accurate, dispelling the mystique that once surrounded right-side hearts.
Source: The New Paper © Singapore Press Holdings Limited. Permission required for reproduction.