Stemi & CABG Questions & Answers PDF

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Stemi & CABG Questions & Answers...

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STEMI & CABG Questions & Answers 1. What does STEMI stand for? ST elevation myocardial infarction

2. What is a STEMI? A serious type of heart attack during which one of the hearts major arteries, the coronary artery, is blocked.

3. What is the difference between a NSTEMI and a STEMI? a NSTEMI can be less serious than a STEMI because the supply of blood to the heart may be only partially, rather than completely blocked. As a result, a smaller section of the heart, may be damaged.

4. What artery becomes blocked in a STEMI? The coronary artery

5. How is an ST elevation detected and what is measured? 12- lead ECG which measures the electrical activity of the heart. Should be done within 10 minutes of being admitted to hospital 6. On and ECG, what do the waves show? P wave atrial depolarisation (initiates contraction of the atrial musculature) PR interval begins at the start of the P wave and ends at the beginning of the Q wave, it represents the time taken for electrical activity to move between the atria and ventricles QRS complex depolarisation of the ventricles ST segment starts at the end of the S wave and ends at the beginning of the T wave, isoelectric line that represents the time between depolarisation and repolarisation of the ventricles T wave ventricular repolarisation (resorting of the resting state) 7. What are the clinical presentations of a STEMI?  Intense chest pain – may radiate to the neck, arms and jaw  Nausea or vomiting  Sweating  Substernal heaviness  Arrythmias  Shortness of breath  Hypertension  Light headed

8. List some risk factors of STEMI, modifiable and genetics Modification  Smoking  Alcohol  Overweight/ obesity  Poor diet  Dyslipidaemia poor cholesterol  Sedentary lifestyle  Diabetes

Genetics  Age (65+)  Men/post-menopausal women  South East Asia  African American  Diabetes type 1

9. What is disease associated with STEMI that causes the thickening of the artery walls? Atherosclerosis

10.

How would you diagnose a heart attack?  ECG  Echocardiogram  Angiogram  Troponin test

11.

What are the side effects of MI?  Arrythmias  Tachycardia  Reduced SV  Reduced CO

12.

Explain the process of Atherosclerosis  Structure: 1. Tunica intima; simple, squamous epithelium – reduces friction 2. Tunica media; smooth muscle, supports the artery & allows vasoconstriction/dilation 3. Tunica externa  The endothelium of the artery wall becomes damaged due to microscopic tears in the tunica intima.  LDL’s that circulate in the blood are small enough to bury into the tunica intima and its underlying smooth muscle.  During the formation of an atheroma, the blood monocytes are recruited and transmigrate across the endothelial layer and into the intima - Here they proliferate, differentiate into macrophages and take up lipoproteins and differentiate into foam cells.  Some foam cells die by apoptosis, creating a lipid rich necrosing nucleus in the centre of the atherosclerotic plaque.  The plaque will continue to grow and consequently reduce the blood flow  Obstruction leads to the narrowing of the artery, which, if a clot is formed and wedged in the artery - Cells will be deprived of oxygen and nutrients and will eventually die

13.

Explain the pathophysiology of an MI  Common blockage following the rupture of an atherosclerotic plaque leading to the formation of a blood clot (coronary thrombosis) - Can be a complete or partial occlusion - Causes tissues to be ischaemic or hypoxic  Without sufficient oxygen, tissues will die  Damaged tissue is comprised of a core surrounded by a border zone of tissue that can fully recover, however, the hypoxic tissue within may be a site for arrythmias.  Collateral blood flow is an important factor in determining the size of the blood clot and the severity of tissue damage  Infarcted tissue does not generate force during systole therefore altering systolic and diastolic function - Disrupts electrical impulses of the heart  There is slow blood flow in the coronary artery - As if the heart is beating too fast or the BP is very high then the demand for oxygen is higher than the supply  Each coronary artery supplies a different part of the heart – depending on the location and the amount of heart muscle involved will determine the level of malfunction - This can cause the hearts ability to pump to alter, causing fatally abnormal heart beats – CARDIAC ARRYTHMIAS

14.

List some medical management for STEMI  ACE inhibitors- lower BP  Beta Blockers- lower BP and HR  GNT spray helps to treat angina  Anticoagulants- prevent fibrin clot formation  Antiplatelets- inhibit platelet formation  Calcium channel blockers- vasodilator  Surgery CABG  Percutaneous coronary intervention angioplasty and stent

15. What is a coronary angioplasty (PCI) A non-surgical procedure that uses a catheter to place a small structure called a stent to open up blood vessels in the heart that have been narrowed by atherosclerosis. Refers to both the process angiogram to assess artery patency, Balloon Angioplasty to crush Atherosclerotic plaques and or insertion of metal mesh stent. Stents may be ‘bare metal’ or ‘drug eluting’. PCI is usually performed immediately after diagnostic coronary angiogram in STMEI  A catheter is inserted into the blood vessels either in the groin or in the arm.  Using a special type of X-ray called fluoroscopy, the catheter is threaded through the blood vessels into the heart where the coronary artery is narrowed.  When the tip is in place, a balloon tip covered with a stent is inflated.  The balloon tip compresses the plaque and expands the stent.  Once the plaque is compressed and the stent is in place, the balloon is deflated and withdrawn.  The stent stays in the artery, holding it open.

16.

What is the surgical procedure used to treat a STEMI? Coronary Artery Bypass Graft (CABG)

17. What is Coronary artery bypass surgery? Direct bypass of the atherosclerotic section of coronary artery Allows blood to flow from proximal to distal via grafting of another artery from above to below CABG surgery may also be indicated over PCI for relief of disabling symptoms in younger and potentially more active patients.

18. What are the two main types of graft used? 1. Arterial  internal mammary artery/ Internal thoracic artery and radial artery 2. Venous  great saphenous vein 19.

Explain why the internal mammary artery may be used  It branches off the ascending aspects of the aorta and supplies a lot of the skin, some of the pectoral muscles and some of the internal viscera and pleura from the chest  Best option to take  Less chance of failure/re-blocking  70-75% patent after 10 years  Don’t need to take the whole artery – quite flexible; take a section and suture it back up You don’t want to take an artery that is full of atherosclerosis - Sometimes be wary and look at the patency before we harvest

20.

Explain why the great saphenous vein may be used  It is harvested from the inside portion of the lower leg  We turn it around because the valves need to be the opposite way around as it is a vein and it is going in place of an artery so the blood needs to be prevented from going the wrong way.  Grafted above and below the incision  Higher failure rate – less pliable, less able to constrict and relax which means they tend to get higher pressures in them therefore there is more of a chance of secondary problems It will only be used if the internal mammary artery and radial artery cannot be used  Due to the lower part of the leg having a fairly substantial venous supply, this will not cause significant problems in the long term but in the short term has the potential to cause a DVT

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Why is a CABG done and what benefit does it allow the patient? To restore blood flow to the cardiac muscle Alleviation of: - SOB; heart muscle is better perfused now - Angina; heart will now receive enough blood - Improved exercise tolerance

- Improved QoL - Reduced dependence on others - Reduced risk of further MI - Possibly return to employment 22. Explain the procedure of CABG Surgery is performed under general anaesthesia (usually a median sternotomy, with the heart arrested on cardiopulmonary bypass) Surgery usually lasts 3 to 6 hours but it may take longer depending on how many blood vessels are being attached A blood vessel is taken from another part of the body It is attached to the coronary artery above and below the narrowed area or blockage this new blood vessel is known as a graft

23. What are some physiotherapy interventions for CABG patients Cardiac rehab Early post-operative mobilisation Exercise prescription/ supervision  effective in reducing postoperative pulmonary complications and returning to preoperative functional capacity

24.

What is the typical surgery procedure done for a CABG?  Median sternotomy - Incision through the centre of the sternum from the manubrium to the xiphisternum to provide access to the anterior chest cavity and the heart - “Gold standard” for a CABG - It is a large incision but largely avoids cutting through muscles largely aside from pectoral aponeurosis

25.

What are the contraindications for a CABG  The lungs get deflated during surgery therefore may cause atelectasis, an increased risk of post-op pulmonary complications and retained secretions  Risk of “post-pump syndrome” – when the patient wakes up with an effectively different personality - Confused - Agitated - Don’t follow instructions well  Small emboli and small air bubbles caused by a passage of blood through the bypass pump

26.

What are the main coronary arteries affected during an MI?  Left anterior descending artery – more severe  Left circumflex artery – more severe  Right coronary artery – if there is a blockage here you can generally stent it

27.

What are troponin levels and how do they relate to an MI? c-Troponin T and c-Troponin I are specific cardiac structural proteins. If there is myocyte injury Troponin will be released.

A group of proteins that help regulate the contractions of the heart and skeletal muscles  Troponin C binds calcium and transports troponin, I so that muscles can contract  Troponin T binds troponin proteins to muscle fibres  Troponin levels are usually so low that standard blood tests are unable to detect them It is important not to interpret and elevated high sensitivity Troponin in isolation, it only indicates an  MI if the clinical presentation also supports this diagnosis.  Normal troponin levels (hs Troponin T 30 ng/l) 28.

State the CABG pre-operative tests  Cardiac catheterisation - Angiogram - Angioplasty/stent  Ultrasound  Chest x-ray  ECG  Dental check  Blood tests  Nasal throat swabs  Respiratory function  Thallium scan  Gastroscopy - To check for duodenal ulceration  Blood sugar levels - Diabetics...