Week 5 - Cardiology Flashcards
What is a clinical trial?
The evaluation of a new therapeutic intervention (i.e. drug, device, procedure) in human volunteers.
Describe the pathway of an action potential as it passes throughout the heart.
SA node>atrial muscle>AV node>common bundle>bundle branches>purkinje fibers>ventricular muscle.
A normal QRS axis is -30 to +90 degrees. How can you tell if there is a normal QRS axis on an ECG?
There should be a positive deflection in leads I and II.
A right axis deviation is +80 to +180 degrees. How can you tell if there is a right deviation on an ECG?
Predominantly negative deflection in leads I and aVL.
A left axis deviation is -30 to -90 degrees. How can you tell if there is a left axis deviation on an ECG?
Predominantly negative deflection in leads II and aVF.
Which leads on an ECG show the electrical activity from the anterior aspect of the heart?
Chest leads V1-V4
Which leads on an ECG show information about the electrical activity from the lateral aspect of the heart?
Chest leads V5 and V6 and limb leads I and aVL.
Which leads on an ECG show information about the electrical activity from the inferior aspect of the heart?
Limb leads II, III and aVF.
What is the difference between a STEMI and an NSTEMI?
A STEMI is caused by complete block of coronary flow.
An NSTEMI is caused by partial block of coronary flow.
Sometimes you can have ST elevation but it is not a myocardial infarction. How would you be sure that it is an MI?
If there is ST elevation in the anterior leads and reciprocal ST depression in the inferior leads.
What does a chest X-ray allow you to visualise on the heart?
Cardiac silhouette - size and position of the heart Great vessels Pulmonary vessels Pulmonary Oedema Pleural effusions
What can an echo doppler show you that a normal echo wouldn’t?
Flow of blood through the heart.
What is a transoesophageal and transthoracic echo?
Transoesophageal is when an ultrasound probe is placed down the throat and the heart is view through the oesophagus.
Transthoracic is when the probe is placed on the chest.
What can be assessed on an echocardiogram?
Heart structure and function, valves, pericardial assessment and inducable ischaemia.
What are the pros and cons of an echocardiogram?
Pros - cheap, available, no radiation, portable.
Cons - requires good acoustic window (good place to place probe for best image), user dependent.
What is the aim of functional stress testing?
Induce ischaemia by increasing the workload of the heart.
How is nuclear perfusion imaging performed? What does is allow you to assess?
Patient takes radioactive tracer and scanned using PET or SPECT, shows perfusion of the heart.
Assess ischaemia and ejection fraction.
What is ejection fraction?
The percentage of blood that is pumped into circulation with each ventricular contraction.
What are the pros and cons of nuclear perfusion imaging?
Pros - availability
Cons - radiation, no structural assessment
What is cardiac CT useful for?
Detecting coronary artery calcium which is a risk for CHD and also studying coronary anomalies i.e. single coronary artery.
What does cardiac CT allow you to visualise? What are its pros and cons?
Coronary artery anatomy and great vessel anatomy.
Pros - good ‘rule out’ for CAD, low risk
Cons - radiation dose, requires low heart rate, no functional assessment of ischaemia.
What is coronary angiography? What does it show?
Catheter inserted into femoral or radial artery and contrast medium injected in and X-ray imaged taken. Shows narrowing of coronary artery.
What are the indications for invasive angiography?
Ischaemia, primary PCI, valve assessment, assessment of ventricular pressure.
What are the pros and cons of invasive angiography?
Pros - gold standard, option for intervention during same procedure, availability.
Cons - radiation, risks - CVA, MI, contrast reaction, bleeding.
What are the indication for cardiac MRI (CMR)?
Assessment of structure and function, perfusion/stress, assessment of great vessels, tissue characterisation.
What are the pros and cons of CMR?
Pros - No radiation, reproducable, gold standard for LV assessment.
Cons - cost, availability, claustrophobia, pacemakers/valve replacement contraindicate
Define heart failure.
Failure of the heart to pump blood at a sufficient rate to meet the metabolic requirements of the tissues - caused by an abnormality of cardiac function and with adequate cardiac filling pressure.
What are the clinical features of heart failure?
Breathlessness, effort intolerance, fluid retention.
What causes of heart failure are common in the UK?
CAD (MI) Hypertension Idiopathic Toxins (i.e. alcohol/chemotherapy) Genetic
What are causes of heart failure that are less common in the UK?
Valve disease, infections (i.e. virus/chaga’s), congenital heart disease, metabolic (i.e. haemochromatosis), pericardial disease (i.e. TB), endocardial disease.
What are the 4 main types of heart failure?
HF-REF (systolic HF)
HF-PEF (diastolic HF)
Chronic (congestive)
Acute (decompensated)
What is the differences between HF-REF and HF-PEF?
HF-REF - patients usually younger, male, coronary aetiology.
HF-PEF - patients usually older, female, hypertensive aetiology
Describe chronic and acute heart failure.
Chronic - present for a period of time, may become acute or have been acute.
Acute - admission to hospital, worsening of chronic or new onset.
Describe briefly in 5 steps the pathophysiology of heart failure.
- Myocardial injury
- Left ventricular systolic dysfunction
- Perceived reduction in ciruculating volume and pressure.
- Neurohumeral activation i.e. RAAS, SNS, natriuretic peptides.
- Systemic vasoconstriction, renal sodium and water retention.
What are the symptoms of heart failure?
Dyspnoea (sometimes when lying flat + at night) and cough
Ankle swelling (+abdomen/legs)
Fatigue
What are the clinical signs of heart failure?
Peripheral oedema (ankles, legs, sacrum, abdomen) Elevated JVP Third heart sound Displaced apex beat (cardiomegaly) Pulmonary oedema (lung crackles) Pleural effusion
The New York Heart Association (NYHA) have a functional classification of heart failure. Briefly describe patient function in the 4 different classes.
I - no symptoms and no limitation in ordinary physical activity.
II - mild symptoms (i.e. breath shortness/angina) and slight limitation during normal activity.
III - Marked limitation due to symptoms, even during very light activity. Only comfortable at rest.
IV - Severe limitations, symptoms even at rest, mostly bedbound.
What investigations for heart failure would be done for every patient with heart failure?
Blood chemistry (U&Es, Cr, urea, LFTs, urate) Haematology - (Hb, RCW) Natriuretic peptides (BNP, NT-proBNP) CXR Echocardiogram ECG
What investigations would be done only in selected patients?
Coronary angiography Exercise test Ambulatory ECG monitoring Myocardial biopsy Genetic testing
What is used to treat acute heart failure treated?
How do these methods work?
Bilevel or continuous airway pressure - peload reduction
Dobutamine, dopamine, milronone - increased inotropy (strength of heart contractions)
Furosemide - natriuesis
Nitrates, morphine - venodilation
Nirates, nitroprusside, dobutamine - arterial vasodilation
Ultrafiltration - aqual natriuesis
What treatment would be required for acute heart failure in a patient with the warm and dry profile?
Adjustment of oral medication
What treatment would you consider for acute heart failure in a patient with the cold and dry profile?
Fluid challenge + inotropic agent
What treatment would be required for acute heart failure in a patient with the warm and wet profile?
Diuretics, vasodilators, ultrafiltration.
What treatment would be required for acute heart failure in a patient with the cold and wet profile?
Diuretics, vasodilators, inotropic agents, vasopressor, consider mechanical circulatory response.
What are the symptoms of MI?
Chest pain, back pain, jaw pain, indigestion, sweatiness/clamminess, SOB, potentially none
What are the clinical signs of MI?
Tachycardia, distressed patient, heart failure (crackles, raised JVP), shock, arrhythmia, none.
What is troponin and what does it mark?
Part of the cardiac myocyte, presence in blood stream is a marker of cardiac necrosis.
What are the 5 different types of MI?
1 - due to primary coronary event 2 - oxygen supply/demand imbalance 3 - sudden cardiac death with possible symptoms of ischaemia 4 - MI associated with stenting 5 - MI associated with CABG
What are some of the non-coronary causes of elevated troponin? (think type 2 MI and chronic causes)
Congestive heart failure, tachyarrhythmias, hypertension, hypotension, sepsis, PE
Renal failure, infiltrative cardiomyopathies i.e. amyloidosis
What could ST depression in the anterior leads indicate? Why is this?
Posterior wall infarct.
Because anterior leads are directly opposite any current generated in posterior wall so posterior ST elevation = anterior ST depression.