CHF
Left Ventricular Outflow Obstruction
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Left Ventricular Outflow Obstruction
, Left Ventricular Outflow Tract Obstruction, LVOTO
See Also
Cardiogenic Shock
Pathophysiology
Left Ventricular Outflow Obstruction (LVOTO) occurs with conditions that impair left ventricular filling
LVOTO results in decreased
Stroke Volume
,
Cardiac Output
and
Cardiogenic Shock
Secondary
Mitral Regurgitation
may occur as the mitral valve is pulled toward obstruction
May increase left atrial pressures and result in
Acute Pulmonary Edema
Causes
Critically ill patients
Hypovolemia
leads to narrowing of the left ventricular outflow tract
Tachycardia
leads to decreased diastolic filling (decreased time in diastole)
Hypertrophic Cardiomyopathy
(
HOCM
)
Abnormally thickened
Myocardium
and abnormal mitral valve movement impair filling
Subaortic Stenosis
Bicuspid Aortic Valve stenosis
Supravalvular
Aortic Stenosis
(SVAS)
Rare condition, associated with Williams Syndrome (most common), as well as
Familial Hypercholesterolemia
Aortic Coarctation
Hyperdynamic left ventricle
Systolic anterior motion of the mitral valve (SAM)
May complicate Mitral valve regurgitation or
Mitral Valve Prolapse
Mitral valve lodges in the left ventricular outflow tract resulting in mechanical obstruction
Findings
Presentations
Cardiogenic Shock
Syncope
or
Near Syncope
Hypotension
Clinical Clues
Tachycardic, hypotensive patients who worsen with
Vasopressor
s or inotropes (due to increased
Tachycardia
)
Cardiogenic Shock
that worsens with
Diuretic
s and
Nitroglycerin
Differential Diagnosis
See
Cardiogenic Shock
Imaging
Echocardiogram
(
PLAX View
)
Left ventricle hyperdynamic and small
Myocardium
or septum may be thickened (
Cardiomyopathy
)
Mitral Regurgitation
may be present
Color Doppler Ultrasound
Mitral valve motion in systole
Measurements consistent with Left Ventricular Outflow Obstruction (LVOTO)
Left ventricle diastolic diameter <2.2 cm
Continuous-Wave Doppler (CWD) with high-velocity, late-peak
LVOT gradient >30 mmHg
Management
Acute Emergent
Early, emergent cardiology
Consultation
Stabilize
Hypotension
Intravenous Fluid
s
Expand left ventricle with
Preload
Slows
Heart Rate
, increasing diastolic filling time
Vasopressor
s
Peripheral
Vasoconstrictor
s (e.g.
Vasopressin
,
Phenylephrine
) are preferred
Avoid inotropes (increase
Heart Rate
and contractility) that worsen obstruction
Manage Tachydysrhythmias
Synchronized Cardioversion
for
Atrial Fibrillation with Rapid Ventricular Rate
Consider
Esmolol
to slow
Tachycardia
s
Other measures
Avoid initial diuresis (decreases
Preload
)
Resources
Left Ventricular Outflow Obstruction (Internet Book of
Critical Care
, Dr. Farkas)
https://emcrit.org/ibcc/lvoto/
Left Ventricular Outflow Obstruction (StatPearls)
https://www.ncbi.nlm.nih.gov/books/NBK470446/
References
DeMeester and Swaminathan (2024) EM:Rap, 9/2/2024
Mallemat and Swaminathan (2024) Crit Bits: Left Ventricular Outflow Obstruction, EM:Rap 11/11/2024
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