Case 6 - HOCM

Question 1

What is the anatomic abnormalities in HOCM patients?

Answer 1

Anatomy

• asymmetric septal hypertrophy 2/2 disorganized mass of hypertrophied myocardial cells
• LV outflow tract obstruction
  
  • systolic anterior motion (SAM) of anterior leaflet of mitral valve approximates hypertrophied septum during systole
• MR
  
  • SAM during systole leads to MR (leaflets do not coapt)
• LVH
  
  • approximation of anterior leaflet of mitral valve with hypertrophied septum = sub-aortic obstruction
  • result - inc LV pressure chamber - > inc LV wall tension –> LVH (Laplace law)
• LV diastolic dysfunciton (2/2 LVH)

Question 2

what are your HD goals for HOCM patients?

Answer 2

Goal:

• Distend LV during systole -> does not allow anterior leaflet to approx with septum = reduces degree of outflow obstruction

1) HR - Slow, Rhythm = Normal

• adequate time for LV filling, inc LVEDP
• LVH -> diastolic dysfunction -> rely on atrial kick
• indicate - BB

2) Preload - High

• inc LVEDP, inc LVEDV - distends ventricle
• indicate - IVF

3) afterload - HIGH

• increased transmural pressure distends the LVOT during systole -> reduces degree of obstruction
• less blood leaves ventricle, keep its distended
• indicate - phenylephrine

4) contractility - Decreased

• indicate - volatile anes, halothane, high dose BB

Question 3

What monitors would you consider for HOCM patients?

Answer 3

1) EKG
* HR, rhythm, ischemia
2) pre-induction arterial line

• beat to beat blood pressure monitoring
• avoid hypotension with induction
• avoid tachycardia during laryngoscopy

3) TEE

• can use when needed
• assess ventricular loading conditions
• asses obstruction

Question 4

How will you induce this patient?

Answer 4

Anesthetic considerations:

• HR - Slow, regular rhythm
• Preload - High
• afterload - high
  
  • increases transmural pressure between aorta and LV which distends the LVOT during systole (distension of LVOT = reduces degree of obstruction)
• contractility - low

Induction:

avoid hypotension and tachycardia during induction

• BZD - amnesia
• Opiod - blunt symp reflex with laryngoscopy and intubation (avoid tachy)
• lidocaine - blunt airway reflex and symp response to laryngoscopy and intubation (avoid tachy)
• etomidate - HD stable
  
  • avoid propofol - dec preload, dec SVR
  • avoid ketamine - tachy
• Sux or ROc
  
  • avoid panc - Tachy
• Have pressors nearby to tx hypotension

Intubation

• gentle PPV, inc intrathoracic pressure leads to dec preload
• intubate when patient is deep (avoid cardiovascular response to laryngoscopy and intubation)

Question 5

what is your anesthesia mainteance in HOCM pts?

Answer 5

• HR - Slow, regular rhythm
• Preload - High
• afterload - high
  
  • increases transmural pressure between aorta and LV which distends the LVOT during systole (distension of LVOT = reduces degree of obstruction)
• contractility - low

Mainteance

• Inhaled anes - Sevo
  
  • myocardial depression, dec SVR to a lesser extent than iso
• avoid opioids with histamine release (morphine)
  
  • dec preload
• fentanyl - fast on, slows HR due to vagotonic effect

Question 6

HOCM patient is pregnant, how would you manage this patient?

Answer 6

• same HD goals apply as nonpregnant patients
• pregnant pts may not be on BB due to assoc with IUGR
• fetal heart monitoring
• left uterine displacement
• hypotension - use phenylephrine
  
  • avoid ephedrine -> inc contract and inc HR can worsen HOCM outflow obstruction