Cardiac Disorders Flashcards
Define stenosis.
STENOSIS = narrowed valve e.g. aortic stenosis produces murmur in rapid ejection phase
What causes the sound of a heart murmur?
Laminar flow usually produces no sound. Abnormal flow causes turbulent blood which produces sound.
Define incompetence.
INCOMPETENCE = valve not closing properly, causing backward flow of blood (REGURGITATION)
What are the acyanotic congenital heart defects?
Patent ductus arteriosus Patent foramen ovale Atrial septal defects (left -> right shunt) Ventricular septal defects (left -> right shunt) Aortic stenosis Pulmonary stenosis Coarctation of aorta Mitral stenosis
What are the cyanotic congenital heart defects? What is required?
Tetralogy of Fallot
Tricuspid atresia
Transposition of great arteries
Hypoplastic left heart
Right -> left shunt AND distal obstruction required (pressure normally lower in the right than the left)
Describe patent ductus arteriosus.
Ductus arteriosus fails to close (fibrose?)
Deoxygenated blood from pulmonary trunk mixes with oxygenated blood in aorta
Left-sided heart failure (+pulmonary vascular disease -> Eisenmenger’s syndrome)
Treat by ligation
Describe patent foramen ovale.
Foramen ovale fails to close at birth
Usually clinical silent as the higher atrial pressure functionally closes the valve
BUT it can allow a venous embolism to reach the systemic circulation (paradoxical embolism)
Describe atrial septal defects.
Left —> right (blood from left returned to lungs instead of going to body)
e.g. ostium primum/secundum atrial defect (inadequate formation of/excessive resorption of), sinus venosus defect
Increased pulmonary blood flow —–> right ventricular overload ———> pulmonary hypertension ———-> right heart failure
Eisenmenger’s syndrome may result
Describe ventricular septal defects.
Left —-> right (blood from left returned to lungs instead of going to the body)
Most commonly in membranous portion of interventricular septum
Left ventricle volume overload ——–> pulmonary venous congestion ——–> pulmonary hypertension
Describe aortic stenosis.
Obstructed aortic valve ——> increased left ventricular pressure ——–> hypertrophy of left ventricle ———-> increased pulmonary artery pressure ——> increased cardiac output ——> heart failure
Describe pulmonary stenosis.
Can be valve, outflow, or branch
Increased RV pressure -> right ventricular hypertrophy -> right-sided heart failure
Describe coarctation of the aorta.
Narrowing of aortic lumen around ligamentum arteriosum —–> increased afterload of left ventricle —–> left ventricular hypertrophy —–> heart failure (shortly after birth)
Normal perfusion of head and upper limbs (supplied before narrowing) but poor perfusion to the rest of the body
Weak delayed femoral pulses and upper body hypertension
Common in Turner syndrome (XO)
Describe mitral stenosis.
Increased left atrial pressure —-> transudation of fluid into lung interstitium ——-> pulmonary hypertension ——–> increased jugular venous pressure ——–> ascites & liver congestion
Describe tetralogy of Fallot.
Outflow of interventricular septum too far anterior and cephalad ->
Ventricular septal defect + overriding aorta (receives blood from both ventricles) + pulmonary stenosis + right ventricular hypertrophy
Pulmonary stenosis —–> increased resistance in bloodflow to lungs —–> right ventricular hypertrophy (compensatory; also due to VSD reducing pressure in ventricle)
Right -> left shunt (deoxygenated blood bypasses lungs -> cyanosis)
Describe tricuspid atresia.
Lack of development of tricuspid valve
No inlet into right ventricle
Complete right -> left shunt required to return blood to right atrium
(e.g. atrial septal defect, patent foramen ovale) + shunt allowing blood flow into the lungs required (e.g. ventricular septal defect, patent ductus arteriosus)
Describe transposition of the great arteries.
Two unconnected, parallel circulations
Right ventricle connected to aorta, left ventricle connected to pulmonary trunk
Not compatible with life unless there is a shunt
Describe hypoplastic left heart.
Left ventricle and ascending aorta fail to develop
Patent ductus arteriosus + patent foramen ovale/atrial septal defect required
What is Eisenmengen’s syndrome?
Chronic Left -> right shunt initially
Severe pulmonary vascular obstruction -> vascular remodelling (due to the lungs activating) occurs until shunt reverses
Right -> left shunt (thereby becomes cyanotic)
Define arrhythmia. What conditions encompass arrhythmia?
ARRHYTHMIA = abnormality of heart rate or rhythm
- bradycardia (HR no atrial contraction)
- tachycardia (HR>100bpm; ventricular or supraventricular)
- ventricular fibrillation (uncoordinated ventricular depolarisation -> no ventricular contraction)
What are some of the causes of arrhythmias?
- ectopic pacemaker activity
- afterdepolarisations
- re-entry loops
Describe ectopic pacemaker activity.
Damaged area of myocardium becomes depolarised and spontaneously active
Ischaemia activates latent pacemaker region which dominates SAN
Describe afterdepolarisations.
Abnormal depolarisation following the AP
Early: more likely if AP is prolonged (longer QT)
Delayed: more likely if [Ca2+]i is high
Describe re-entry loops.
Accessory conduction pathways:
Connects ventricular myocardium rather than the Purkinjie fibres
- conducts faster than the AVN (P-R interval is shortened)
- slow spread through ventricles + concurrent AVN conduction = wide QRS complex with “slurred” initial upstroke (delta wave)
Unidirectional block:
Complete block = no arrhythmia
Incomplete block = excitation takes long route and spreads the wrong way through the damaged area - circus of excitation produced
note: several small re-entry loops in the atria (due to damage e.g. mitral valve stenosis) causes AF
What is Wolff-Parkinson-White syndrome?
Accessory conduction pathway causing supraventricular/ventricular tachycardia
- conducts faster than the AVN (P-R interval is shortened)
- slow spread through ventricles + concurrent AVN conduction = wide QRS complex with “slurred” initial upstroke (delta wave)
Common cause of sudden death in adults
