Atrial Fibrillation and Heart Failure Flashcards
What is the coagulation cascade?
extrinsic pathway
intrinsic pathway
common pathway
What is the extrinsic pathway?
it is activated when there is external injury that results in blood loss to the vascular system.
What is the intrinsic pathway?
it is activated when there is internal injury within the vascular system.
What is the common pathway?
this is where the extrinsic and intrinsic pathway meet to form a clot
What is PT/INR and what does it measure?
prothrombin time and international normalised ratio.
INR calculated from PT level - used to measure in patients taking warfarin
measures extrinsic and common pathways
What clotting factors does PT/INR assess?
I, II, V, X (clotting factors of the common pathways), and factor VII (clotting factor of the extrinsic pathway)
What does the PT/INR tell us?
how fast prothrombin turns into thrombin
What does a high PT time indicate?
High results mean the patient has a prolonged time forming a clot:
clotting disorders, vitamin k deficiency, types of cancers, liver disease, or the patient is taking an anticoagulant
What is aPTT?
activated partial thromboplastin time
assesses intrinsic and common pathways
What clotting factors does aPTT assess?
clotting factors: I, II, V, X (clotting factors of the common pathways), and XII, XI, IX, VIII (clotting factors of the intrinsic pathway)
prekallikrein, high molecular weight kallikrein
Differential diagnosis of a chesty cough?
viral infection, pneumonia, COPD
Differential diagnosis of heart racing?
anxiety, dysrhythmia (atrial fibrillation, superventricular tachycardia)
Recommended alchohol intake?
<10 units a week
ECG indications for atrial fibrillation?
absent P wave
irregular RR interval
What is atrial fibrillation?
most common atrial tachyarrhythmia.
It is caused by abnormal and irregular heart rhythm in which electrical signals are generated chaotically throughout the upper chambers (atria) of the heart.
Which is more concerning - AF or VF?
Ventricular arrhythmia is more concerning - life threatening. Very strictly managed in hospital setting. AF can be managed in a community setting.
Symptoms of AF?
- Your heart rate is usually a lot faster than normal.
- Your heartbeat is irregular - that is, an abnormal heart rhythm (an arrhythmia).
- The force of each heartbeat can vary in intensity. AF can be asymptomatic.
Common symptoms includes; palpitation, chest discomfort, dizziness, syncope, shortness of breath, lethargy.
Cardiac causes of AF?
- ischaemic heart disease
- rheumatic heart disease
- hypertension
- sick sinus syndrome
- pre-excitation syndromes
less common:
- cardiomyopathy
- pericardial disease
- atrial septal defect
- atrial myxoma
Non cardiac causes of AF?
- acute infection (e.g., pneumonia)
- electrolyte depletion
- lung carcinoma
- intrathoracic pathology e.g, pleural effusion
- pulmonary embolism
- thyrotoxicosis
Management of AF
- Rate control using beta blocker or calcium channel blocker
- Rhythm control using electrical and/or pharmacological approach or ablation
- Stroke Prevention
- Treating underlying cause
Most common complication of AF?
stroke
Why does AF cause stroke risk?
AF causes blood to stagnate in the atria because it is only partially ejected (trying to beat 5x a second). Stagnation causes clotting which when the heart properly beats can go off into the bloodstream.
How can stroke be prevented in AF?
anticoagulant e.g. warfarin
left atrial appendage occlusion device implanted surgically in patients who can’t take anticoagulants.
What is thrombosis?
Thrombosis is the formation of potentially deadly blood clots that blocks blood supply.
Types of arterial clots and conditions from this?
- Stroke (>24 hr symtoms) and TIA (mini stroke symptoms <24hrs)
- Myocardial infarction
- peripheral arterial clot - gangrene
Types of venous clots and conditions from this?
- pulmonary embolism
- deep vein thrombosis
What is Virchows triad?
3 main factors which can lead to clot formation
SHE
stasis of venous circulation
hypercoagulability
endothelial damage
Causes of the three factors of virchows triad?
stasis: immobility, varicose veins, heart failure..
hypercoagulability: cancer, sepsis, HRT etc. can be acquired or hereditary reasons
- primary polycytemia - RBC malignancy, genetic component JAK 2 mutations
- secondary polycytemia - can be caused by high altitudes, oxygen sats in blood are low
endothelial damage: surgery, trauma, PICC lines
endothelial dysfunction: smoking, hypertension
Why does endothelium damage cause clots?
Von willebrand factor released - platelets stick to it and release more factors leading to clot formation
How does warfarin work?
acts to inhibit vitamin K cycle and vitamin K dependent clotting factors in liver
works on factors X and II
Factor Xa inhibitors
rivaroxaban
apixaban
Factors IIa inhibitors
dabigatran
Stroke risk assessment
CHADVASC
congestive heart failure
hypertension
age >75
diabetes mellitus
stroke/TE
vascular disease
age 65-74
sex
Bleeding risk assessment
HAS-BLED
hypertension
abnormal renal/liver function
smoke
bleeding
labile inr
elderly
drugs/alcohol
Which patients can factor 10a inhibitors not be given in and what should be given instead?
patients with metallic heart valves
warfarin
Heart Failure
inability of the heart to pump blood around the body
Causes of heart failure
- Coronary Artery Disease
- Hypertension
- Valvular Heart Disease
- Alcoholism
- Viral Infection
- Diabetes
- Congenital Heart Disease
- Others: Obesity, Obstructive Sleep Apnea, Smoking, Idiopathic
ejection fraction
stroke volume/ end diastolic volume
Echocardiogram
checks how heart’s chambers and valves are pumping blood through the heartq
diastolic dysfunction occurs when ….
heart fills to much
class 1 HF
Cardiac disease, but no symptoms and no limitation in ordinary physical activity, e.g. no shortness of breath when walking, climbing stairs etc.
class 2 HF
Mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity.
class 3 HF
Marked limitation in activity due to symptoms, even during less- than-ordinary activity, e.g. walking short distances (20–100 m).
Comfortable only at rest.
class 4 HF
Severe limitations. Experiences symptoms even while at rest.
Mostly bedbound patients.
