Disorders of Cardiac Function

Question 1

What are the symptoms of Pericarditis?

Answer 1

Sharp pain, increasing with movement, pericardial rub, widespread ST elevation & PR depression

Question 2

What is Pulsus Paradoxus?

Answer 2

Exaggeration of normal variation in arterial pulse volume with respiration (eg Carotid weak or absent in inhalation and strong on exhalation). Indicative of cardiac tamponade.

Question 3

What is the pathophyisology of Constrictive Pericarditis?

Answer 3

Fixed CO due to scar tissued pericardium following Pericarditis

Question 4

What is the pathophysiology of Rheumatic Heart Disease?

Answer 4

Complication of immune-mediated response to group A streptococcal throat infection. Can cause mitral valve stenosis after 10+ years.

Question 5

What is stenosis?

Answer 5

A narrowing orafice or damaged valve leaves leads to failure of valve to fully open & increased pre-valve workload.

Question 6

What is regurgitation?

Answer 6

Failure of valve of fully close, sometimes caused by valve prolapse, allowing back flow of fluid.

Question 7

Describe Phase 4 of the myocyte action potential

Answer 7

Resting. -90mV. 3Na⁺/2K⁺-ATPase pump actively transporting Na⁺ out and K⁺ into the cell.

Question 8

Describe Phase 0 of the myocyte action potential

Answer 8

Rapid depolarisation. Rapid influx of Na⁺ due to opening of fast Na+ channels at depolarisation threshold of -70mV.

Question 9

Describe Phase 1 of the myocyte action potential

Answer 9

Initial repolarisation. Fast Na+ channels close. Small decrease in polarity due to efflux of K⁺ via slow K⁺ channels and influx of Cl⁻

Question 10

Describe Phase 2 of the myocyte action potential

Answer 10

Plateau phase. K⁺ efflux slowly increasing balanced by Ca²⁺

Question 11

Describe Phase 3 of the myocyte action potential

Answer 11

Rapid repolarisation. Ca²⁺ close, unbalanced K⁺ efflux opens rapid K⁺ channels.

Question 12

What are the ECG signs for Brugada Syndrome?

Answer 12

V1-V3 ST elevation & RBBB