case 9 - chest pain Flashcards
Which blood vessels develop atherosclerotic plaques?
Elastic arteries, and large/medium muscular arteries
What is the pathophysiological process of the formation of atherosclerotic plaques?
1.) endothelial cell injury increases vascular permeability, platelet adhesion and leukocyte recruitment
2.) lipoproteins, particularly oxidised LDL, seep into arterial intima
3.) cytokines released, attracts monocytes which take up LDL forming foam cells.
4.) smooth muscle cells proliferate and deposit ECM, then become foam cells. T cells are recruited.
What are the key gross features of an atherosclerotic plaque?
Fibrous cap on media of artery, underlying lipid core/necrotic centre with lipids and inflammatory cells
Which type of lipoprotein is associated with the development of atherosclerotic plaques?
(oxidised) LDL
What is a myocardial infarction?
A cardiac event in which blood flow is obstructed to a region of myocardium, causing cell death.
What are the key stages in the development and progression of a myocardial infarction?
Atherosclerotic plaque development, plaque rupture/acute plaque change, coronary artery occlusion, ischaemia, infarction, inflammatory response, fibrosis
Why can acute plaque change cause an MI?
Exposure of the necrotic centre of plaque causes coagulation, forming a thombus that can occlude the vessel.
What is an infarction of the heart?
When ischemia of the myocardium causes permanent damage, causing necrosis of the issue and the release of troponins and inflammatory mediators into the blood stream.
What type of necrosis occurs at a myocardial infarct?
Coagulative necrosis
What process do MIs heal through?
Fibrosis - forms a collagenous, fibrous scar
What features of a patient history may suggest MI?
Smoking, hypercholesterolaemia, history of MI
What is the most significant symptom of MI?
Chest pain
How is MI chest pain often described?
Crushing pain, with radiation to the mandible and left arm
What are the symptoms associated with MI?
nausea, sweating, lightheadedness, tachycardia
What imaging techniques can be used to diagnose MI?
Coronary angiography, echocardiography
Which cardiac biomarkers indicate probable MI?
troponin (CTn1), creatine kinase-MB
What ECG changes are present in a STEMI?
Significant and persistent ST segment elevation or anterior ST segment depression
What ECG changes are present in a NSTEMI?
ST segment depression or T wave inversion
During exercise stress testing, what does ST segment depression indicate?
Reversible myocardial ischaemia
What are the ECG changes visible during symptomatic episodes of stable angina?
ST depression
What are the key differences between an episode of stable angina vs a myocardial infarction?
Myocardial infarction:
can come on at rest, lasts longer, not relieve by nitrate sprays, troponin.ck-mb positive, ST elevation
What are the non-modifiable risk factors for CVD?
Genetic predisposition, family history, increased age, male gender, history of CVD
What are the modifiable risk factors for CVD?
Smoking, hypertension, LDL cholesterol, sodium intake, Diabetes Mellitus type II, stress, alcoholism, physical inactivity, obesity, inflammation
What are the ways that hypertension increases the risk of CVD?
damage to endothelium causes plaques to form, increased resistance to pumping causes ventricular hypertrophy, increased risk of plaque rupture and embolism/MI, high pressure stretches arterial walls causing aneurysms
What is the immediate treatment for stable angina?
Vasodilator - usually glyceryl trinitrate sublingual spray for rapid symptoms relief
What are the short term/complication reducing treatments for stable angina?
Antiplatelet agent, e.g. low dose aspirin.
What are the long term management strategies for stable angina?
statin, antihypertensives, dietary changes, green prescription, exercise, smoking cessation.
What are the ratios of fuel sources used for cardiac metabolism in adults in a normal state?
70% carbohydrates, 30% lipid
What is fuel utilization in cardiac metabolism modulated by?
Substrate availability, hormones, oxygen availability, workload/exercise
Which hormones modulate fuel utilization in cardiac metabolism?
Insulin, glucagon
Which type of metabolism does the heart usually utilise?
Oxidative metabolism - citric acid cycle drives the electron transport chain
What is the main substrate of cardiac metabolism in the fed state?
Carbohydrates
What is the main substrate of cardiac metabolism in the fasting state?
Lipids/fatty acids
How does cardiac metabolism change in the ischemic heart?
Oxidative metabolism drops due to poor O2 supply, the heart relys of glycolysis (an anaerobic process using glucose)
What are some of the classes of medicines used to ease symptoms/prevent complications in the treatment of MI?
nitrates for vasodilation, opioids for pain, fibrinolytics to break down thrombi, antiemetic for nausea/vomiting, anticoagulants to prevent thrombus formation
What medicines are used to prevent further complications in MI treatment?
Statins, dual antiplatelet therapy
What is the key medicine used to alter disease progression following MI?
ACE inhibitors - an antihypertensive
What is the role of fibrinolytics in MI treatment?
Administered after MI diagnosis, help to break down clots/thrombi
What is the basic mechanism of action of fibrinolytics?
They facilitate the conversion of plasminogen to plasmin, which is an enzyme that helps to break down fibrin in clots.
Which fibrinolytic is typically used for MI treatment?
Tenecteplase
Which anticoagulant (LMWH) is typically used in MI treatment?
Enoxaparin
What are the trends in IHD mortality in NZ from the 1940s to present?
From 1940s to 1960s there was an upward trend is IHD, then afterwards there was a decline in mortality. This trend was observed in males and females, though males have a higher rate of mortality.
Which sex has a greater prevalence of IHD mortality?
Male
What are some of the reasons for declining IHD mortality since the 1960s?
treatment advances, emergency infrastructure, preventative medications, tobacco control, diet/exercise awareness, primary care screening
What is a green prescription?
A health intervention aimed at providing individuals/whanau with tools to improve their lifestyle and health.
