Cardiac Pathology Flashcards
What gross histological change correlates with white blood cells’ (WBCs) invasion into cardiac tissue during the first week after an MI?
- yellow pallor
- dark discolouration
- white scar
- red border around yellow border
The yellow pallor is indicative of inflammation characterised by neutrophils and macrophages within the myocardium. In the first 24 hours after an MI, there is dark discolouration due to coagulative necrosis. During the first week, there is inflammation signified by the yellow pallor. After which (1 to 3 weeks), granulation tissue emerges marked by a red border entering from edge of infarct. Months after, white scar forms- this is due to fibrosis.
What is the key complication in the first 24 hours of an MI?
- fibrinous pericarditis
- coronary artery aneurysm
- arrhythmia
- mitral insufficiency
Arrhythmia is the key complication in the first 4 to 24hrs after a myocardial infarction. Coagulative necrosis is occurring (pyknosis, karyorrhexis, karyolysis). This necrosis can damage the heart’s conduction system resulting in arrhythmias
What are the characteristics of stable angina?
- Chest pain that occurs with exertion and/or emotional stress
- severe and crushing chest pain (>20 mins)
- chest pain that occurs at rest
- bradycardia
Stable angina is a type of ischaemic heart disease which is due to atherosclerosis of coronary arteries. The reduced blood supply cannot meet the demand of the myocardium during exertion which results in reversible injury to the myocytes. It presents as chest pain (<20mins) that radiates to the left arm or jaw, dyspnoea and diaphoresis. Symptoms are relieved by rest or glyceryl trinitrate (GTN).
What are the classic signs of a cardiac tamponade?
- hypotension, muffled heart sounds, increased jugular venous distension (JVD)
- tachycardia, dyspnoea, fever
- Bradycardia, weakness in arms, diaphoresis
- Hypertension, palpitations, chest pain
The classic signs of cardiac tamponade are known as Beck’s triad which includes hypotension, muffled heart sounds and increased JVD. Cardiac tamponade is a pathological compression of the heart caused by excess fluid in the pericardial sac. Cardiac output is reduced as the myocardium cannot contract efficiently leading to hypotension. The accumulation of fluid in the pericardial sac has an insulating effect leading to the heart sounds becoming muffled. JVD is increased as a result of increased venous pressure due to the backflow of blood into veins which is due to the reduced cardiac output.
What heart condition is Turner’s syndrome associated with?
- tricuspid atresia
- truncus arteriosus
- coarctation of the aorta
- patent ductus arteriosus
coarctation of the aorta
Turner’s syndrome is a sex chromosome disorder of female sexual development (45, XO). Symptoms include short stature, ovarian dysgenesis, lymphatic defects, cystic hygroma, webbed neck and lymphoedema. In respect to cardiac pathology, it is most commonly associated with preductal coarctation of the aorta which causes hypertension in upper extremities and weak pulses in the lower extremities.
Which of the following conditions is Marfan’s syndrome most commonly associated with?
- endocarditis
- restrictive cardiomyopathy
- arrhythmia
- aortic dissection
Aortic dissection begins as an intimal tear which then allows for blood to pass through the weakened media of the aortic wall. The most common cause of aortic dissection is hypertension but it can also be caused by connective tissue diseases such as Marfan’s syndrome and Ehlers-Danlos syndrome. Marfan’s syndrome is caused by a gene mutation in FBN1 on chromosome 15 leading to a defect in fibrillin (a glycoprotein that forms a sheath around elastin). It causes cystic medial necrosis of the media which is due to fragmentation of elastic laminae with an accumulation of myxoid material in aortic media leading to aortic dissection. Other cardiac pathology associations include aortic valve incompetence and mitral valve prolapse. Other findings of the syndrome are tall stature with long extremities, hypermobile joints, pectus excavatum, arachnodactyly and upward/temporal subluxation of lenses.
What is the most commonly involved coronary artery in myocardial infarction (MI)?
- Right coronary Artery (RCA)
- Left anterior descending artery (LAD)
- left circumflex artery (LCA)
- posterior descending artery (PDA)
The LAD is the most commonly involved artery in MI. It leads to the infarction of the anterior wall and anterior septum of the left ventricle (LV). Order of coronary artery involvement: LAD>RCA>Circumflex.
An ECG is performed and reveals a progressively increasing PR interval and dropping of QRS complexes at regular intervals. Which of the following is the most likely diagnosis?
- Second-degree heart block (Mobitz type 2)
- hyperkalaemia
- Second-degree heart block (Mobitz type 1)
- First-degree heart block
Second-degree heart block (Mobitz type 1) is a disease of the atrioventricular node. Typical ECG findings include progressive prolongation of the PR-interval with associated regular dropping of QRS complexes.
A patient is noted to have an abnormally shortened PR-interval on their ECG. Which of the following is the most likely cause?
- Wolff-Parkinson-White (WPW) syndrome
- left bundle branch block
- Right bundle branch block
- Atrioventricular nodal fibrosis
a short PR-interval indicates abnormally short conduction time between the atria and ventricles. This is typically caused by the presence of an accessory pathway between the atria and ventricles. WPW syndrome is an example of this kind of disorder. In WPW syndrome, an accessory pathway known as the bundle of Kent is present. Most individuals are asymptomatic, however, there is a risk of sudden death without treatment.