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)

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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