So, perhaps this exact table has never appeared in the past papers, but there have been numerous questions which have asked the candidate to manage a haemodynamically unstable cardiac surgical patient. And in these questions, inevitably the candidate must discuss the manner in which they would approach the contractility, preload, afterload, and so forth. It is therefore important to consider these variables. An analogous chapter exists in the cardiology section, and applies this framework to the management of heart failure in the ICU.
Variable | Determinant | Interventions |
Preload |
Venous return (MSFP -RAP) / SVR |
|
Diastolic filling time |
|
|
Atrial contribution to diastolic filling |
|
|
Ventricular compliance |
|
|
Afterload |
Ventricular size |
|
Ventricular volume |
||
Chamber radius |
||
Wall thickness |
|
|
SVR |
|
|
Aortic valve resistance |
|
|
Aortic compliance |
|
|
Contractility |
Metabolic substrate |
|
Coordination of depolarisation |
|
|
Functional muscle mass |
|
|
Autonomic tone |
|
|
Hormonal contribution |
|
|
Electrolyte gradients |
|
Norton, James M. "Toward consistent definitions for preload and afterload."Advances in physiology education 25.1 (2001): 53-61.
ROTHE, CARL. "Toward consistent definitions for preload and afterload—revisited." Advances in physiology education 27.1 (2003): 44-45.
Noble, M. I. "Problems in the definition of contractility in terms of myocardial mechanics." European journal of cardiology 1.2 (1973): 209-216.
Solaro, R. John. "Regulation of cardiac contractility." Colloquium Series on Integrated Systems Physiology: From Molecule to Function. Vol. 3. No. 3. Morgan & Claypool Life Sciences, 2011.
Penefsky, Zia J. "The determinants of contractility in the heart." Comparative Biochemistry and Physiology Part A: Physiology 109.1 (1994): 1-22.