Cardiovascular Physiology, Cardiac Cycle and Haemodynamic Regulation — WACS Viva & Clinical Scenarios (Physiology and Applied Physiology)

Exam-style cardiovascular physiology, cardiac cycle and haemodynamic regulation viva scenarios with examiner probes and model answers for ANAESTHESIA…

Scenarios covered

• SCENARIO 1: Draw a fully annotated Left Ventricular Pressure-Volume Loop. Define stroke volume, end-diastolic volume, end-systolic volume, and ejection fraction. Illustrate on separate diagrams the specific changes produced by: (a) an isolated increase in preload, (b) an isolated increase in afterload, and (c) an isolated increase in myocardial contractility.
• SCENARIO 2: A 28-year-old male involved in a road traffic crash presents with severe pelvic trauma and hypovolaemic shock (BP 80/50 mmHg, HR 135 bpm). Draw and explain Guyton cardiac output and venous return curves on a single set of axes. Detail the concept of Mean Systemic Filling Pressure (MSFP) and explain how acute haemorrhage, fluid resuscitation, and sympathetic activation alter these curves.
• SCENARIO 3: Compare and contrast the electrophysiology of a ventricular myocardial action potential with that of a sinoatrial node pacemaker cell. Detail the underlying ionic currents, phases, threshold potentials, and absolute versus relative refractory periods, including the physiological mechanisms of chronotropic and inotropic modulation by the autonomic nervous system.
• SCENARIO 4: Describe the physiological determinants of coronary blood flow to the left and right ventricles. Explain why the subendocardium of the left ventricle is uniquely susceptible to ischaemia during periods of tachycardia and hypotension, defining the coronary perfusion pressure equation and metabolic autoregulation.
• SCENARIO 5: Describe the normal central venous pressure (CVP) and jugular venous pulse (JVP) waveform. Define the mechanical events corresponding to the a, c, and v waves and the x, x-prime, and y descents. Describe how this waveform is altered in atrial fibrillation, tricuspid regurgitation, and cardiac tamponade.