Cardiac CPGs Flashcards
ACS definition
A spectrum of conditions
ranging from unstable angina to NSTEACS to STEMI, which all share common pathophysiology of a disrupted atherosclerotic lesion, followed by superimposed thrombus formation.
ACS signs and symptoms
L) sided chest pressure nausea and vomiting SOB pale and diaphoretic pain radiating to jaw, neck, back anxiety hT (R infarct) HT (L infarct) ST segment elevation or depression t wave inversion in NSTEACS pathological q waves
Pathophysiology of Atherosclerosis in relation to ACS
- irritant/injury - toxins, hyperlipidaemia, HT
- endothelial dysfunction causing breakdown of cells
- LDL infiltrates tunica intima
- macrophages follow, ingesting LDLs creating foam cells (dead macrophages) - accumulation of LDL and foam cells called a fatty streak
- smooth muscle cells from tunica media migrate into tunica intima
- SMCs make fibrous cap over fatty streak (Fat Cap) which further disrupts endothelium. Contains collagen and elastin proteins
- SMCs put Ca2+ into endothelium causing hardened arteries
- inflammatory substances breakdown collagen and weaken the cap
- rupture of plaque exposes contents to blood
- initiates clotting cascade
- thrombus formation - reduces arterial size and blood flow
- ischaemia/infarct to distal point of occlusion.
Clotting cascade - intrinsic pathway
in blood, occurs when Hageman Factor XII (12) comes into contact with damaged vasculature
Clotting cascade - extrinsic pathway
owing to release of tissue protein Tissue Factor III from damaged tissue into circulating blood
Clotting cascade
Prothrombinase (with ca)
prothrombin converts to thrombin, converting
Fibrinogen to fibrin (soluble)
with help of fibrin stabilising factor (Factor XIII)
becomes a
Stablisied Fibrin clot (insoluble)
What causes pain in ACS?
buildup of waste products (lactic acid) generated as the o2 starved cells switch from aerobic to anaerobic metabolism
Why do we not give GTN to a right ventricular/inferior infarct with BP <160?
Right ventricle is preload dependent because the muscle is small. It needs good preload to stretch ventricle to activate Starling’s Law. Take away pre-load and reduce contractility results in reduced CO
Whe no Aspirin in psychostim OD?
increased risk of CVA results from vasospasm not thrombosis as SBP greater than 160
Why no GTN in HR over 150
decreased fill time causes disproportionate drop in BP if preload reduced
Why no GTN in bradycardia
HR already low, GTN will take away SV therefore CO will be poor
Tachycardia (narrow complex) definition
A group of tachyarrhythmias greater than 100bpm that originate from above the ventricles or bundle of his
Causes of SVT
drugs hyperthyroidism conduction abnormality caffeine emotional stress cocaine abuse heart failure WPW
SVT signs and symptoms
regular rapid greater than 100 narrow qrs palpitations dizzy SOB, crackles chest pain hT
SVT patho - AVRT
Involves AV node conduction and an accessory pathway outside the AV node. It is triggered by a PAC that activates the ventricles via the AV node before reactivating the AV node via an accessory pathway, forming a re-entry circuit.
Valsalva patho
- bearing down increases intra-thoracic pressure
- Venous return is decreased, decreasing BP
- baroreceptors detect drop in BP
- sympathetic compensation increases HR and causes peripheral vasoconstriction
- Pressure is released
- sudden increase in venous return and cardiac output as ITP returns to normal
- barorececeptors detect increase
- parasympathetic innervation occurs via vagus nerve causing interruption of re-entry circuit
Pulmonary oedema definition
Leakage of fluid from pulmonary circuit and interstitium into alveoli of lungs due to imbalance between: capillary hydrostatic and oncotic pressure, lymphatic drainage and alveolar permeabillity
Causes of APO
cardiogenic - CCF/LVF, AMI
non-cardiogenic - drowning, toxic inhalation, high altitude, fluid overload, anaphylaxis, renal disease, sepsis
Signs and symptoms of APO vs infective
hx of APO, CCF, cardiac meds, bilateral, fine crackles, tachy, SOB, poor perfusion
Infective: course crackles, febrile, sepsis, cough, hx of infection, antibiotics, unilateral, chest pain, sputum
Patho of APO
- LVF/CCF
- decreased ejection fraction/stroke volume
- increased left ventricular end diastolic volume
- increased left ventricular pressure
- increased left atrial pressure
- increased pressure in pulmonary circulation
- increased pulmonary capillary hydrostatic pressure
- hydrostatic pressure exceeds oncotic pressure
- fluid shift into lung tissue and alveoli
- loss of surfactant
- alveoli collapse
- reduced surface area for gas exchange
- increase WOB
- hypoxia
- inadequate perfusion