Factors determining LIMA Flow
OVERVIEW
- Flow = pressure gradient/resistance x diastolic time
- Multiple factors affecting LIMA flow: — anatomy — demand — physiology — drugs
ANATOMICAL
- kinking of graft
- stitching of graft
- narrowing of anastomosis
- external obstruction by distended heart or pericardial tamponade
DEMAND
- heart rate
- wall tension
- contractility
PHYSIOLOGICAL
- blood pressure gradient (coronary perfusion pressure = arterial diastolic pressure – LVEDP)
- diastolic filling time and pressure
- resistance in graft (atherosclerosis, vasospasm, clot)
- run off due to distal disease
- venous pressure
- viscosity of blood (SIRS response, Hb)
- hypoxia causing local vasodilation
- autonomic tone
- vessel closure as perfusion pressure falls
- coronary-subclavian steal syndrome
DRUGS
- vasodilation (GTN)
- vasopressors (noradrenaline)
- inotropes (milrinone -> increased wall tension and contractility)
- IABP (increases coronary artery blood flow and myocardial work)
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC