A BLOODY history involving both Roman and Christian rituals formed the tradition of leaving romantic notes for your beloved on Valentine’s Day. While the brain and hormones are mainly responsible for your feelings of romance and love, it’s your heart that is sent a flutter when that special person walks in the room.
What sort of a job does the heart actually do?
The average human heart only weighs 300 grams. The circulating blood volume in an average size adult is 4-5 litres. Every day, your heart beats about 100,000 times, sending more than 7,000 litres of blood surging through your body. Although it’s no bigger than your fist, your heart has the mighty job of keeping blood flowing through almost 100,000 km of blood vessels that feed your organs and tissues.
Why do we link love with the heart and that fluttering feeling?
The heart has a lot of nerve fibres that control heart rate and stretch, but which are also linked into the sympathetic system – the part of your nervous system linked with reactions and some emotional responses. Some people do feel their heart fluttering. Actually, we all have extra heartbeats: it’s just that some people feel them and some people don’t. The term ‘palpitations’ describes the sense of awareness of your heart beating. The overwhelming majority of people we see in the clinic for heart palpitations don’t have a clinical problem.
Can you literally ‘break your heart?’
Yes. If you have a large enough heart attack, you can actually rupture the heart. In the past, for someone who’d had a large heart attack we’d simply put him or her in hospital, and because the damaged, mushy heart muscle made the heart weak it could actually rupture. If this happens the outcome became very bad, very quickly. But these days if you get chest pains and you call the ambulance and they bring you to the hospital, we know that one of your arteries is blocked. We try and open that artery up as quickly as possible by giving you powerful clot-busting drugs, or taking you to the catheter lab. Here we use a balloon to open the artery up and put a stent in the artery. This approach has been shown to minimise the amount of heart muscle damage, which translates to less patients have heart failure, less patients having nasty heart rhythms and less patients dying. That whole approach is now why people can walk out of hospital four to five days after a heart attack. This has been one of the great success stories of medicine in the last 40 years.
You can also have a ruptured heart through trauma, although fortunately in Australia we don’t see a lot of that.
When does the human heart form?
It starts to form in the first few weeks after fertilisation. The development of the heart is interesting, because it really just forms as a tube. It moves out of the chest, and then back in, and it twists and hollows out and then forms chambers and valves. You need a lot of things to go right in exactly the right sequence. I’m always amazed how often it happens right. It may be because a lot of the ‘not happening right’ you just never know about, for example due to miscarriage.
Is the heart always in exactly the same place?
It’s fascinating how often medical drama TV shows put the chest X-ray up and the heart’s on the wrong side. It’s a condition called dextrocardia and is very rare, very rare. I have seen it occasionally.
When did the first heart transplant take place?
The first heart transplant was performed in the late 1960s in South Africa. Transplanting a heart mechanically is really not that difficult: it’s simply a matter of plumbing – connecting all the pipes up. What the field really encountered quickly was the problem of tissue rejection. While the surgical capability was there, we needed all the other support to catch up and be able to facilitate it. An enormous amount of work started in the 1970s on anti-rejection drugs. Now it’s a much more common procedure, but we still have a shortage of transplant organs. That’s now the single biggest problem, that we still have people sitting on waiting lists.
What is it that allows you to understand the heart so well?
We’ve been really lucky in our field that we’ve been able to use imaging to look at the beating heart, for example through ultrasound and MRI scans. You can watch a beating heart inside a chest. We’ve learnt an enormous amount about the physiology and the mechanics and the anatomy of the heart, which has enabled us to take our knowledge gained through autopsies and animal experiments and laboratory work to a whole new level. It’s been really exciting.
Here at SAHMRI we’re going to open a human imaging pod later this year on campus. This will extend our imaging capacity for clinical work, and we’ll be able to do a lot more high-end research projects and trials here. This will complement the new hospital being built next door and the cyclotron that we use to create new tracing materials.
What’s hot in heart research right now?
There is an enormous amount of interest in how we can fix heart valves without a big cut down the chest and undergoing bypass and all those types of things. There are a lot of people who need valve repair or replacement but they’re actually too sick to have surgery – this whole field started as a way to help these people. Some techniques are now in the trial stage.
There is also a huge amount of excitement about developing devices and interventions for heart rhythm problems and developing new drugs to control cholesterol. Also, heart failure is still a major focus. Heart failure is already the largest consumer of public health expense in the country, and in an aging population it’s going to become more and more common.
Ironically, one of the most exciting areas of development is actually back in the context of weight loss and health. Here at SAHMRI we’ve just done some research which shows that if you just target those major lifestyle risk factors really well - such as losing weight - this actually has a huge benefit in terms of managing cardiac arrhythmia, even an existing condition.
What sort of heart research do you do at SAHMRI?
We have a number of areas that we focus on. We are interested in disorders of blood vessels – that is, what actually causes heart attacks and strokes, and how we can diagnose and prevent these from happening. We also look at heart structure and function, focussing on the imaging of the heart and heart failure. Our researchers investigate heart rhythm disorders, working in the laboratory with cells, but also all the way through to the clinic and clinical trials. Ultimately we will also do health systems research, where we will look beyond the trials to see how these proven therapies are actually being used out there in practice. We want to do work that changes real health outcomes.
SAHRMI is running a Valentine’s Day research funding program. For more information, see www.sahmriwindows.com