Question 16
Compare the structure, function and coronary circulation of the right and left ventricles.
College Answer
The question sought information on the structure (anatomy), function (physiology) and vascular supply of the right and left ventricle. Good answers provided detail in each section e.g. values for ventricular pressure rather than simply stating “high- and low-pressure systems”. Many marks may be gained by a simple anatomical description & labelled PV loop for each ventricle. Many candidates focussed solely on the coronary circulation, to which only a proportion of the marks were allocated
Discussion
| Domain | Right ventricle | Left ventricle |
| Shape | Irregular; vaguely triangular | Conical |
| Valves | Tricuspid and pulmonic | Mitral and aortic |
| Thickness | Relatively thin: 2-5mm | Three times thicker: 7-11mm |
| Mass | ~ 26g | ~90g |
| Position in the chest | Right and anterior | Left and posterior |
| Blood supply | RCA and circumflex | LAD and circumflex |
From a functional point of view, the college asked to compare PV loops of the two ventricles, which might actually be insufficient (as it is hard to represent everything on the same diagram). Here is an optional diagram which emphasises the differences of the RV:
And here is a table which offers a summary of the differences:
| Domain | Right ventricle | Left ventricle |
| End-diastolic volume | Slightly higher than LV | Slightly lower than RV |
| End-systolic volume | Slightly higher than LV | Slightly lower than RV |
| Stroke volume | The same | The same |
| Systolic pressure | 25 mmHg | 120 mmHg |
| Diastolic pressure | 0 mmHg | 3-8 mmHg |
| ESPVR (contractility) | Lower | Higher |
| EDPVR (elastance) | Lower | Higher |
| Ea (Afterload) | Lower | Higher |
| Stroke work (PV loop area) | Lower | Higher |
References
Pasipoularides, Ares. "Right and left ventricular diastolic pressure–volume relations: a comprehensive review." Journal of cardiovascular translational research 6.2 (2013): 239-252.