Cardiology Flashcards
What is the diastolic phase of the cardiac cycle?
Heart chamber is in a state of relaxation and fills with blood
What is the systolic phase of the cardiac cycle?
The heart chambers contract and pumps blood to body via the arteries
What valves close in S1
Mitral and tricuspid
What are the three shunts in fetal circulation?
Foramen ovale
Ductus arteriosus
Ductus venosus
What do the fetal shunts become in the adult structure?
Foramen ovale - Fossa Ovalis
Ductus anteriosis- Ligamentum Arteriosum
Ductus Venosus - Ligamentum Venosus
What is the mechanism of action of aspirin?
(Anti-platelet)
Cox-1 inhibitor
Inhibits the production of tromboxane A2
What is the mechanism of action of Clopidogrel?
Inhibits ADP-mediated platelet activation
Irreversibly inhibits binding if ADP to the purine receptor on platelets
Complications of acute MI
Ischemic (angina, re-infarction)
Mechanical (heart failure, cardiogenic shock)
Arrhythmic (atrial or ventricular arrhythmia, SA or AV node dysfunction)
Embolic (CNS or peripheral)
Inflammatory (pericarditis)
Sudden cardiac death
Where to auscultate for the Aortic valve?
Medial end of the 2nd right intercostal space
Where to auscultate for the Pulmonary valve
Medial end of the second left intercostal space
Where to auscultate for the Tricuspid valve?
4th intercostal space at the lower left sternal border
Where to auscultate for the Mitral valve?
5th left intercostal space at the mid- clavicular line
What does JVP determine?
whether right atrial pressure is high or normal
What cardiac disease impacts electricity of the heart
Arrhythmia
What happens to vessel walls in hypertension?
Can damage arteries, making them less elastic.
Arterial walls thicken as a response to wall stress
Where do the coronary arteries originate from?
The root of the aorta
The left main coronary artery divides into
1) the left anterior descending artery
2) the circumflex artery
Where does the right coronary artery supply blood to?
The right ventricle, the right atrium, the SA node, AV node
What is cardiac output?
The amount of blood pumped by the heart in a minute
What are the determinants of cardiac output?
Heart rate, contractility, preload, and afterload
How do you measure Ejection Fraction (EJ)?
Stroke volume over End diastolic volume
Which valves close when the ventricles contract?
Mitral and tricuspid
Layers of the heart
Endocardium
Myocardium
Epicardium
What is the pericardium?
fibro-serous sac that encloses the heart and the roots of the great vessels
What is the definition of myocardial infarction?
Death of cardiac tissue (myocardial necrosis)
What is the definition of angina?
Chest pain or discomfort due to inadequate supply of oxygen to the heart
Defining factors for stable angina?
1) Constricting discomfort in the front of the chest/ neck/ shoulders/ arms
2) it is precipitated by physical exertion
3) Relieved by rest or GTN spray in 5 minutes
ECG definition of a STEMI
STEMI = >1mm ST elevation in at least 2 consecutive limb leads
Or >2mm ST elevation in at least 2 consecutive precordial leads
Or new onset left-bundle branch block
What is cardiac preload?
The force that stretches the cardiac myocytes prior to contraction. It is the volume of blood in ventricles at end of diastole
What is cardiac afterload?
Pressure or resistance the left ventricle has to overcome to eject blood (squeeze)
Valves on left hand side of heart?
Aortic (AV) and mitral (SL)
Chronic management of patient after MI
-Aspirin
-Second antiplatelet – Clopidogrel, prasugrel or ticagrelor
-B-blocker – slows HR and decreases risk of arrhythmia
-ACE inhibitor – decrease LV dilation reducing preload
-Statin
Acute management of MI
MONA
Morphine –> given for pain relief (+ metoclopramide antiemetic)
Oxygen –> given if SpO2 is below 94%
Nitrates –> GTN given to vasodilate veins and reduce preload on the heart
Aspirin –> loading dose of 300mg given
Describe the coronary artery territories on an ECG
Leads I , aVL , V5 , V6 (Lateral Territory )=> Circumflex artery
Leads II, III, aVF (Inferior Territory) => Usually Right Coronary Artery but Left Circumflex artery in ‘left dominant’
Lead V1-V4 (Anterior Territory) => LAD artery
Diagnosis of STEMI
ECG: ST elevation (>1-2 mm in at least two contiguous leads)
Or new LBBB
Troponin: Raised
Management of STEMI
- Within 120 minutes -> Emergency Coronary Angiography +/- PCI
- If no PCI in 2 hours, fibrinolytic agent => Coronary Angiography +/- PCI in 2-24 hours after fibrinolysis.
- DAPT
- Anti thrombotic agents
What is Coronary Angiography
Insertion of a catheter via the femoral artery or radial artery.
The catheter passed to the coronary artery vessels with x-rays for guidance and contrast dye is injected to allow visualisation of the coronary artery.
Balloon catheter can be inserted to open up a blockage and a stent can be inserted into the blocked artery.
Ischemia Vs Infarction
Ischemia: blood flow decreased (results in hypoxia -> insufficient oxygen)
Infarction: blood flow cut off (results in necrosis)
Risks of coronary angiography
Bleeding
Infection
Stroke
Haematoma
Contrast-induced nephropathy (CIN)
Myocardial infarction
Hypotension
Arrhythmias
Underlying mechanism of action of Beta blockers?
Decrease HR and contractility therefore decreasing oxygen demand of heart.
Contributes to electrical stability.
Underlying mechanism of morphine in treatment of ACS
Reduces myocardial oxygen demands by decreasing chest pain and anxiety