W5 MC Flashcards
Common patients admitted to ICU? Provide one exampe
Orthopaedic (eg MVA)
Neurological (eg Stroke/TBI)
Cardiac (eg CABG, MCI, heart failure)
Respiratory (COPD, bronchiectasis, CF)
The pumping action of the heart occurs via…
A very rapid process which requires synchronised movement of different structures of the heart (ie valves close, electrical conductivity)
Role of the heart
Pumping blood (oxygenated) throughout the body
Also…delivers waste products eg C02 back to the lungs to be removed
Electrical conductivity is governed by….
SA (sinus atrial) node and purkinje fibres (fire 60-100 times per minute ie number of times the heart beats)
The electrical conductivity of the heart ensures what in the heart contracts first? What does this allow?
The electrical conductivity of the heart ensures that the atria contract first, allowing blood flow into the ventricles, via the opening and closing of valves.
What are the two heart valves?
Tricuspid & bicuspid
The opening and closing of the valves is well timed to prevent….
Prevents early leaking of blood into the ventricles and prevent back flow of blood back into the atria.
What is the myocardium? What is it comprised of? Where is it thicker?
Muscular layer of the heart wall. Comprised of cardiac muscle and is much thicker in the ventricles
Contraction of what pushes blood throughout the body?
The myocardium
What is the heart also covered by?
A fluid-filled sac (pericardial sac)
Pericardial fluid is found between….
The two thin layers of pericardium
What is the two layers of the pericardium?
Inner layer that covers the heart (visceral pericardium/epicardium)
Another layer which attaches the heart to the chest wall (parietal pericardium)
What happens at the right atrium?
Receives deoxygenated blood from the body via SVC, IVC and coronary sinus
What happens at the right ventricle?
Receives deoxygenated blood from the right atrium via right atrioventricular orifice and sends it to lungs via pulmonary trunk
What happens at the left atrium?
Receives oxygenated blood from the lungs via pulmonary veins
What happens at the left ventricle?
Receives oxygenated blood from left atrium via left atrioventricular orifice and sends it to body via aorta
What are 5 ways of measuring cardiac function?
Heart rate
Stroke volume
Cardiac output
Mean arterial pressure
Systemic vascular resistance
What is normal Mean Arterial Pressure?
80-100mmHGg
What is normal cardiac output?
5-6L
What is normal stroke volume?
50-100mls
Heart rate what is it determined by?
Determined by signals from the sinoatrial node, which automatically depolarizes at an intrinsic rate of 60 to 100 times each minute.
What is stroke volume?
The volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction.
What is cardiac output?
The amount of blood pumped by the heart each minute and is the mechanism whereby blood flows around the body, blood flow to the brain and other vital organs
What is mean arterial pressure? What is it influenced by?
The average arterial pressure throughout one cardiac cycle (systole, and diastole).
MAP is influenced by cardiac output and systemic vascular resistance.
What is systemic vascular resistance?
Relates to diameter of blood vessels (small diameter = ↑ resistance) and viscosity of blood (increased viscosity (hematocrit) = ↑ resistance)
What is myocarditis?
Acute cardiac presentation
Myocardium (heart muscle) becomes inflamed (can be focal or diffuse inflammation)
Commonly caused by viral infections but also can be due to autoimmune response
What is pericarditis? How does it present?
Acute cardiac presentation
The pericardium (lining of the heart) becomes inflamed
Presents as chest pain due to rubbing of inflamed lining
What is ischaemic heart disease also known as?
Coronary artery disease (CAD) or coronary heart disease (CHD).
What is ischaemic heart disease/CAD/CHD?
- Inadequate blood supply to the heart due to a blockage in the blood vessels which supply it.
- Narrowing can be cause by a clot/embolism, however, is most frequently caused by atherosclerosis.
Ischaemic heart disease: what is atherosclerosis?
- Atherosclerosis is the build-up of plaque inside the blood vessels
Ischaemic heart disease includes…
- Includes Acute Myocardial Infarctions (AMI) (STEMI & NSTEMI) and angina (unstable & stable).
CHD is the ….. cause of death in Australia (for both indigenous & non-Indigenous)
How many Australians does it impact?
Leading cause of death
Impacts 600,000 Australians
CHD is implicated in how many deaths?
1 in 5
ABTSI are …. more likely to experience a coronary event?
- ABTSI people are 3x more likely to experience a major coronary event & with higher case fatality.
Top 5 causes of death Male vs Female
Male
1. CHD
2. Dementia
3. Lung cancer
4. Cerebrovascular disease
5. COPD
Female
1. Dementia
2. CHD
3. Cerebrovascular
4. Lung cancer
5. COPD
What is angina pectoris?
- Form of ischaemic heart disease
- Discomfort experienced when the heart muscle is deprived of 02
Note: patients can have silent ischemia ie experience episodes without pain
How is stable angina relieved?
- Stable angina is relieved promptly with rest or by taking nitroglycerin
Note: unstable angina is not relieved with rest
Where is discomfort present in angina pectoris & what can aggravate it?
- Discomfort above the waist & may be experienced in the chest, jaw, shoulder, back, or arms (can replicate heart attack symptoms)
- Typically aggravated by exertion or emotional stress
Acute myocardial infarction is a form of…. also known as?
Ischaemic heart disease
A heart attack
What happens in an acute myocardial infarction?
- Caused by decreased or complete cessation of blood flow to a portion of the myocardium (heart muscle)
Symptoms of AMI?
- Chest pain- retrosternal and may be described as pressure of heaviness. Usually > 20 mins, not affected by positional changes or movement
- Referred pain down arm, mandibular pain or epigastric discomfort.
- Can present as dyspnea or fatigue and be accompanied by sweating, nausea, abdominal pain and syncope (also reflux, epigastric pain?)
- Presentations are considered a medical emergency.
- Can vary in presentation- can be mild and present as palpitations or be quite dramatic and cause cardiac arrest.
What symptom do women commonly experience in an AMI that men do not?
- Nausea, feeling light-headed or unusually tired
How can infarcts be classsified?
Can be classified according to:
* Anatomical location of the left ventricle involved: eg: anterior, posterior, circumferential
* Degree of thickness of the ventricular wall involved:
- Transmural (full thickness)
- Subendendocardial (only part of the myocardial wall)
What does transmural mean in regards to an AMI?
Full thickness (in related to the degree of the ventricular wall present in AMI)
What does subendendocardial mean in regards to an AMI?
Only part of the myocardial wall
Criteria for acute, evolving or recent MI
- Typical rise &/or fall of biochemical markers of myocardial necrosis (troponin) with at least one of the following:
- Ischemic symptoms
- ECG changes indicative of new ischemia (new ST elevation or new/presumed to be new LBBB)
- Development of pathological Q waves in the ECG
- Imaging of new loss of viable myocardium or new Reginal Wall Motion Abnormality
Common ECG finding for cardiac patients?
ST segment can either elevate or depress in MCI patients. ECG will demonstrate that there is a complete loss of sinus rhythm during a myocardial infarction. There is still activity from the SA node which causes electrical impulses to be recorded but there is absolutely no structure to these.
Complications of MI
- Sudden death - Usually within hours; from ventricular tachycardia (VT)
- Arrhythmias - First few days; due to changed blood flow and conduction
- Persistent pain - 12 hours to a few days; from extension of infarct
- Heart Failure - variable time frame; from ventricular dysfunction.
- Cardiomyopathy.
- Mitral valve incompetence – first few days; from papillary muscle dysfunction
- Ventricular aneurysm - 4 weeks or more; stretching of new scar tissue
- Pericarditis - 2 to 4 days
- Transmural infarct with inflammation of the pericardium
DAP HMM VPT
What causes sudden death after an AMI?
Ventricular tachycardia
How is ischaemic heart disease diagnosed?
Cardia* Cardiac stress test (community outpatient – if someone is stable enough to do. Progressively increases in intensity eg incline). Monitoring blood pressure, ECG, etc
* Coronary angiogram to assess for any blockages in the main vessels
What is percutaneous coronary intervention?
- A group of minimally invasive procedures used to unclog blocked coronary arteries & restore blood flow to ischemic areas
More info:
* Is the treatment choice for acute presentations
* Performed at cardiological centres of excellence -? Accessibility
* Catheter inserted through femoral or radial arteries
* Very few contraindications
* Can be done even if cardiogenic shock up to 12–36 h after infarction
* Not ideal for multiple vessel disease or in patients with diabetes - CABG has better outcomes
In a percutaneous coronary intervention where is the catheter inserted?
Femoral or radial arteries
What are the two main types of percutaneous coronary interventions?
-Coronary angioplasty balloon: using a catheter a balloon is expanded in the artery which compresses the plaque to the wall (balloon is then removed?)
- Coronary angioplasty with drug eluting or bare-metal stent: stent widened artery to maintain artery width and plaque compressed against wall (stays in?)
What is the risk of recurrence (plaque) after coronary angioplasty balloon & angioplasty with stent?
- 30% risk of recurrence after coronary angioplasty balloon
- 15% restenosis rate for coronary angioplasty with stent (drops to 10% when stent is combined with medication)
Common arteries requiring angiogram balloon/stent?
Circumflex artery
Anterior descending artery (left)
Immediate hospital care for cardiac conditions?
- Cardiac monitoring/Coronary Care Unit- 12 lead ECG
- Oxygen (6-8L via facemask)- indicated for hypoxemia
- Pain relief e.g. morphine
- Nitrates- Sublingual glyceryl trinitrate (GTN)
- Administer antiplatelet agents (clopidogrel or ticagrelor)
- Venous access
- Straight to the lab for angio+/- stent
- Beta-blockers
- Treatment of acute pulmonary oedema (if present)
