Complication of MI: Acute mitral regurgitation
Authors: Victória Silva Reviewers: Juliette Hall, Raafi Ali *Angela Kealey * MD at time of publication
S3
Indicates rapid overfilling of ventricle
S1 S2 S3
Calcified plaque formation (atherosclerosis**) commonly in the posterior descending artery
Plaque ruptures
Exposed plaque contentsàPlatelet adhesion and aggregation
Artery becomes partially or completely occluded
Mitral Regurgitation**
(Back flow of blood from left ventricle to left atrium during systole)
↑ Left atrial pressure
Blood from left atrium backs up into pulmonary venous system
↑ Pulmonary venous pressure
↑ Hydrostatic pressure in alveolar capillaries
↑ Fluid leak from alveolar capillaries to interstitium (pulmonary edema**)
↓ Gas exchange
Attempt at
physiologic compensation à ↑ Respiratory rate
Tachypnea
Holosystolic murmur
Heard loudest over the mitral valve (5th intercostal space, mid-clavicular line), with radiation to the axilla
↑ Volume of blood to left ventricle during diastole
↓ Blood supply to the portion of the ventricle that supports the papillary muscle à↓ Muscle movement
Left ventricle dysfunction
↓ Blood supply to the posterior medial papillary muscle
Cell death (myocardial infarction)
Papillary muscle ischemia (muscle is intact but cannot contract)
↑ Blood in right atriumà↑ Blood in superior vena cava
↑ Blood in internal jugular vein
↑ Jugular venous pressure (JVP)
Redistribution of interstitial fluid when lying flat (reduced effect of gravity)
↓ Forward blood flow from left ventricle to aorta
↓ Stroke volume (SV)
↓ Cardiac output (CO) CO = SV x HR (heart rate)
Sympathetic nervous system attempts to physiologically compensate
↑ Heart rate
Tachycardia
↓ Blood pressure (BP) because BP = CO X SVR (systemic vascular resistance)
Cardiogenic shock**
Papillary muscle rupture
Papillary muscle unable to provide adequate tension on mitral valve
Mitral valve unable to stay closed during systole
Orthopnea
Difficulty breathing
Dyspnea
Paroxysmal nocturnal dyspnea
**See corresponding Calgary Guide slides for more details
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published November 25, 2023 on www.thecalgaryguide.com