taking a look under your skin! andrew scott. a human heart
Post on 27-Dec-2015
Embed Size (px)
Taking a Look Under Your Skin!Andrew Scott
A Human Heart
The HeartRight AtriumRight VentricleLeft AtriumLeft Ventricle
The Cardiac Cycle
The Coronary ArteriesThe heart is a big muscle so needs a blood supply to work.
It doesnt use the blood inside the heart it has its own blood vessels.
These arteries are called the coronary arteries and are very important.
Heart DiseasesUKs biggest killer40% of all deathswww.heartstats.org240,000PEOPLE DIE OF HEART DISEASE EVERY YEAR!!!!!
Coronary Artery Disease
Fat in your artery.
What happens to all that fat?It can cause chest pain ANGINA.It gets bigger and can stop the blood to the heart a HEART ATTACK.OR it can break off and:Get stuck on the way to the heart a HEART ATTACK.Get stuck in your lungs PULMONARY EMBOLISM.Get stuck in your brain a STROKE.
Imaging the Heart
X-Ray Contrast Angiography X-RAY All we see is ribs when we x-ray the heart.To see the heart and blood vesselswe inject iodine CONTRAST into a vein which absorbs x-rays like bone.Taking pictures of vessels like this is called ANGIOGRAPHY.
Angiography of the coronary arteriesFatWhat the coronary arteries would look likeNormalWith a plaqueWhat we see in x-ray contrast angiographyVessel wallBloodThin bit where disease isNormalWith a plaque
A real x-ray contrast angiography!
UltrasoundHigh frequency sound waves.Put small probe on skin between ribs.See valves and heart moving.
Which is best?X-ray Contrast AngiographyIs good for seeing coronary arteries.Uses ionising radiation.
Need to inject iodine contrast dye.
UltrasoundIs good for seeing the valves move.Uses high frequency sound waves.Need to look between the ribs.Both have their uses but neither is ideal.
Magnetic Resonance Imaging MRI
What can we get pictures of?
Back to the heart!
MRI Coronary Angiogram
Movies of the Heart
Slicing up the Body
TaggingWe can see how the different bits of the heart move.
Blood FlowBlack Blood flows in to the screen.White Blood flows out of the screen.
A Faulty ValveWatch for the jet of blood shooting backwards through the valve!
Contrast AgentIf we inject a gadolinium compound (contrast agent) the magnetic field is increased wherever the contrast agent goes.The increased magnetic field means that the radio wave comes back more quickly.
Vascular MRIAorta and Lungs
Pictures of the brain!
Pictures of your thoughts!When you use part of your brain, extra blood flows to that part of your brain with more oxygen.
Oxyhaemoglobin and deoxyhaemoglobin alter the magnetic field, changing how quick the radio waves come back.
A Multi-Disciplinary Team
Thank you for email@example.comAndrew ScottPhD Student (in Physics)Cardiovascular Magnetic Resonance UnitRoyal Brompton and Harefield NHS Trust.National Heart and Lung Institute, Imperial College.
Insert a cardiac MRI cine here. To impress.**This is the heart. Its a particularly interesting organ and Clinicians (Drs) and researchers like to look at and study it. To see it, obviously we can remove it from someone who has died and consented to use of their body for medical research but what about if we want to see a live heart?
Well get back to this, but first well look at the heart a bit more. This is a simplified diagram of what it does. Right atrium, right ventricle, left atrium, left ventricle.
What does it do?
The atria contract, then the tricuspid or mitral valves close to stop blood flowing backward. The ventricles contract and the pulmonary and aortic valves close and the tricuspid and mitral valves open again.
The valves have no muscle and are just flaps moved by the blood flow. The lubdup sound you hear through a stethoscope is the sound of the valves closing.
The blood from the body comes into the right atrium and out of the right ventricle to the lungs, where it collects oxygen molecules (turning deoxyheamoglobin into oxyheamoglobin) and then flows into the left atrium and out of the left ventricle, where it delivers oxygen to the rest of your organs.
A diagram where the blood flowsFrom http://en.wikipedia.org/wiki/Image:Humhrt2.jpg imageFrom http://www.fi.edu/learn/heart/enrichment/gallery.html diagram
From http://www.imcpl.org/kids/guides/health/circulatorysystem.html Circulatory system. **Play this movie in a new window.
Explain briefly why we have valves.**What can go wrong with the heart?
Lots heart disease kills around 238,000 people/year. The UKs biggest killer.
The most common thing is coronary artery disease. This is where the saturated fats you eat in burgers, crisps, cheese, butter, bacon sandwiches, chocolate, fried chips, gets stuck in the blood vessels that feed the heart. If you smoke, do little exercise or drink lots of alcohol this becomes more likely.
The heart, like any other muscle needs a supply of oxygen and it has its own set of blood vessels, called the coronary arteries and coronary veins, which supply and return the blood.
This is what happens to parts of your blood vessels after years of eating these saturated fats! Bits of these plaques as we call them, can break off and get stuck in your tiny coronary arteries and cause a heart attack. Alternatively, they can get stuck in your brain and cause a stroke or in your lungs and cause a pulmonary embolism. Either way its pretty bad news.
In a heart attack, the blood cant get to the heart and the bit of heart muscle supplied by the blocked artery can stop working or even die!
If you get really big plaques in your coronary arteries that stop some of the blood from reaching the heart, it can cause really bad chest pains, known as angina.
Other problems with the heart include birth defects, known as congenital heart disease. This might be a bit of the heart that didnt grow or a something that grew in slightly the wrong place or shape.
There are other diseases that can affect the heart including Thalassemia, a problem with the oxygen carrying heamoglobin in the blood, the treatment for which can cause Iron to collect in the heart and also some cancers affect the heart.Different heart diseases, including: congenital, cardiomyopathy, tumours, coronary heart disease.***You can also have a problem in your genes a birth defect congenital heart disease.
And some other diseases can affect the heart.*****Dilated cardiomyopathy means that the heart has dilated (expanded is too fat, but not from eating to much).*Can anyone tell me how we can see someone's heart without ripping open their chest? This might be to study how it works or to see if something is wrong with it.
We can use an x-ray, but if we do it like we would for broken bones all we would see would be the bones around the body. So we inject some dye made of Iodine into the blood vessels. If we want to look for blockages in the coronary arteries we put a wire into a vein in the leg and push it up through the body and the heart to the coronary arteries. We inject the iodine and look for a narrowed artery.
We can use a special x-ray known as a CT or CAT scan which produces slices through the body. Again we need to use the iodine dye.
Alternatively we can use ultrasound like we would for babies in the womb. We would use this to look for mis-shapen hearts or broken valves.
We can inject a different kind of dye which is radioactive and we can trace with a special camera called a gamma camera in a field of techniques known as nuclear medicine.
Alternatively we can use an MRI scan which well talk about more.
The problem with nuclear medicine is that it uses potentially unhealthy radiation which can increase your risk of developing cancer as do the first two techniques which use x-rays. The iodine dye used with the x-ray techniques can also be harmful to the kidneys in some cases.
Ultrasound doesnt use harmful dyes or radiation but the images can often be a bit crap..., and we cant see through the ribs with it so we have to look between them.
The various modalities and what they are used for.European Journal of Cardio-Thoracic Surgery Volume 32, Issue 3, September 2007, Page 532
*What it is very briefly and why it is so good.
This is an MRI scanner, we have 2 of these at the Royal Brompton and one in a trailer so we can tow it to other places if need be.
They also use them in other hospitals for looking at other parts of the body, often the brain.
You lie on the bed and you have a thing like a mat strapped around your chest for a heart scan. You are inside the narrow tunnel for around an hour for most scans. If you are very claustrophobic you cant have the scan or if you are too fat! In America they have larger scanners for really fat people. Here we have to use scanners designed for horses.
The scanner is very noisy, and you need to wear earplugs or special headphones while you are in their. The scan doesnt hurt at all, you can listen to music in the headphones and you and the person doing the scan can t