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Cardio Week 4 > ICL 5.23: Hypertrophic Cardiomyopathy > Flashcards

ICL 5.23: Hypertrophic Cardiomyopathy Flashcards

1
Q

why is hypertrophic cardiomyopathy so important?

A

it’s the #1 cause of sudden cardiac death in athletes….

anomalous coronary arteries are the 2nd cause; they are NOT inherited

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2
Q

what is HCM?

A

a disease caused by any one of several gene mutations coding for the sarcomere

there is diversity in phenotypic expression and clinical course; so different genes have different malignancies

there’s over 1400 genetic mutations

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3
Q

what are the pathological changes seen in the heart in patients with HCM?

A
  1. LV outflow tract obstruction = murmur!
  2. diastolic dysfunction –> EF is usually just fine; it’s not a squeezing problem it’s just that the ventricle wall gets so thick there’s no space to fill and you can hear an S4
  3. myocardial ischemia –> coronary arteries are on the outside of the epicardium and the thicker the myocardium gets, the harder it is for the endocardium to get blood
  4. mitral regurgitation
  5. systolic dysfunction (end stage or burned out)
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4
Q

what is the epidemiology of HCM?

A

the amount of HCM is probably underestimated because a lot of times it’s clinically silent and gets missed

1:500 prevalent in the general population

peak incidence is in infants <1 years old

slight male predominance

higher in african american children than white/hispanic

most common cardiomyopathy!!

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5
Q

what are the 3 categories of symptoms seen with HCM?

A
  1. heart failure
  2. chest pain
  3. arrhythmias
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6
Q

what are the most common presenting symptoms of HCM? in order

A
  1. chest pain
  2. SOB
  3. palpitations/murmur
  4. presyncope/syncope
  5. poor feeding
  6. failure to thrive
  7. tachypnea
  8. easy fatigability
  9. suddenly cardiac arrest
  10. death
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7
Q

why does tachypnea develop with HCM?

A

tachypnea = abnormally rapid breathing

when you have ischemia/poor ventricular function, you develop an anion gap acidosis

you body fixed acidoses with tachypnea = compensatory respiratory alkalosis so you blow off CO2 to try and get your pH more balanced again

so people will confuse tachypnea for a respiratory problem when it could potentially be an ischemia issue

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8
Q

what is the most common symptom of HCM under 1 year old?

A

murmur is the most common!!

the most exhausting thing you can ask a kid to do is feed so if they’re taking longer or having to take breaks, maybe it’s a heart problem

may present with other signs and symptoms of heart failure like tachypnea, poor feeding and poor growth

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9
Q

what is Noonan HCM?

A

male Turner’s syndrome = excess nuchal skin, similar facial features

Noonan’s patients typically have HCM or branch pulmonary stenosis

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10
Q

Turner’s is associated with which cardiac abnormality?

A

coarctation of the aorta

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11
Q

what are the most common symptoms of HCM over 1 year of age?

A

most kids are asymptomatic but you could see:

  1. abdominal pain, decreased appetite, intolerance of food
  2. dyspnea on exertion
  3. fatigue
  4. atypical or angina
  5. presyncope/syncope particularly during or immediately following exertion*** they need a significant cardiac workup if this is the case; don’t say it’s dehydration
  6. palpitations
  7. sudden cardiac arrest
  8. death
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12
Q

why is there a murmur with HCM?describe the murmur seen with HCM?

A

LV outflow tract obstruction is due to a combination of septal hypertrophy and systolic anterior motion of mitral valve**

the degree of the murmur is based on the amount of time the mitral valve is in the outflow tract = subaortic obstruction

there will be a harsh ejection murmur usually loudest at the apex = LLSB – it may radiate to the axilla and base but rarely to the neck

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13
Q

what causes the murmur heard with HCM to increase or decrease?

A

INCREASES:
1. valsalva = decreased preload

  1. standing = decreased preload

decreased preload allows the mitral valve to clamp down and cause more obstruction

DECREASES
1. handgrip = increased afterload

  1. squatting = increased afterload and preload

if you increase preload or afterload, the mitral valve can’t close for as long and won’t cause as much obstruction

think of the song, a little bit louder now you stand up and a little bit softer now you squat down!

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14
Q

what physical exam findings will you see with HCM?

A
  1. murmur
  2. mitral regurgitation
  3. S3 or S4
  4. paradoxic splitting of S2
  5. brisk and bifid arterial pulses
  6. diffuse LV apical impulse on palpation
  7. parasternal lift
  8. signs of CHF = pulmonary congestion, peripheral edema, JVD
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15
Q

how do you diagnose HCM?

A
  1. clinical suspicion*
  2. echo**
  3. EKG*
  4. genetic testing
  5. additional testing = Holter, exercise stress test, cardiac MRI, catheterization
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16
Q

what is a Holter test?

A

assess for arrhythmias, part of routine surveillance

used to diagnose HCM

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17
Q

how are EKGs used in the diagnosis of HCM?

A

they’re sensitive but NOT specific!!

you might see:
1. prominent Q waves in the inferior and lateral leads

  1. enlarged P waves in II
  2. left axis deviation
  3. inverted T waves in lateral leads

Seattle Criteria for HCM can be associated with PVCs and WPW

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18
Q

what is the easy way to tell if there’s an axis deviation?

A

put your left thumb up to lead I and right up to lead aVf

if I is positive and aVf is negative then it’s left axis deviation

if I is negative and aVf is positive then it’s right axis deviation

19
Q

do we do EKG screenings for HCM?

A

no because it’s sensitive but not specific so you’re gonna get a lot of false positives

we’ve been trying to come up with something to find specifically HCM but we aren’t there yet

20
Q

what is the gold standard for diagnosing HCM?

A

echo!!

you’re looking for:

  1. unexplained increased wall thickness
  2. systolic anterior motion of the mitral valve
  3. LVOT obstruction is dynamic = it changes based on exercise

when you exercise, diastole shortens and for someone with a diastolic function issue like in HCM, this is really bad because you’re shortening filling the ventricles and decreasing preload which allows the mitral valve to clamp down for longer and cause more obstruction

21
Q

how do you differentiate HCM form an athletic heart?

A
  1. HCM has an unusual pattern of LC hypertrophy
  2. the LV cavity is huge in athletes so that they can accommodate blood and their EDV is huge; they don’t have a diastolic issue – HCM has a tiny LV cavity!!
  3. HCM will have left atrial enlargement because atrial hypertrophy doesn’t happen well
  4. HCM have low VO2 which basically means HCM won’t do well on an exercise test
22
Q

why do we care about the thickness of the heart wall?

A

patients with a thickness more than 3 cm have very increased rates of sudden death

so wall thickness is a risk factor for sudden death!

23
Q

what is the genetic abnormality that causes HCM? inheritance?

A

autosomal dominant

there’s 15 ones that cause over 1400 mutations but the main ones are B-myosin heavy chain and myosin binding protein C

they have variable expressivity and penetrance though

24
Q

what conditions are associated with HCM?

A
  1. Fabry disease
  2. Noonan syndrome
  3. Pompe disease
  4. Fatty Acid Oxidation Deficiency
  5. Mitochondrial dysfunction
25
Q

what is Fabry disease?

A

alpha galactosidase A deficiency

x-linked

treated with enzyme replacement

highly associated with HCM

26
Q

what is Noonan syndrome?

A

characterized by dysmorphism, short status and CHD

highly associated with HCM

27
Q

what is Pompe disease?

A

acid maltase deficiency = excess glycogen

autosomal recessive

poor muscle tone

highly associated with HCM

28
Q

who should you screen for HCM?

A

first degree relatives of patients diagnosed with HCM

screen every 12 months by echo and then every 5 years after age 21

29
Q

what types of arrhythmias are associated with HCM?

A

may have both atrial and ventricular arrhythmias! this is what kills people with HCM!!

they’re mainly age related though; babies don’t have arrhythmias

  1. non-sustained ventricular tachycardia = 3+ PVCs = significant increased risk of sudden cardiac death
  2. SVT
  3. bradyarrhythmias

pharmacologic treatment is aimed at symptoms/improved functional capacity/slow disease progression; NOT prevention of arrhythmias

30
Q

which factors predispose you to having arrhythmias in HCM?

A
  1. myocardial hypertrophy
  2. myocyte diarray
  3. myocardial fibrosis
  4. myocardial ischemia
  5. autonomic disturbance
31
Q

what are the risk factors for sudden cardiac death?

A
  1. family history of SCD
  2. unexplained syncope
  3. non-sustained ventricular tachycardia = >3 beats at >120 bmp
  4. massive LV hypertrophy >30 mm
  5. abnormal BP response to exercise; failure to increase SBP by at least 20 mmHg or fall >20 mmHg from peak exercise BP

2-3 risk factors puts you at a seriously high risk for SCD and you NEED an ICD = internal cardiac defibrillator

once you get older stroke and heart failure can also kill you but in the younger ages, SCD is what’s gonna kill you

32
Q

what is the criteria that would mean you need an ICD?

A
  1. 2+ risk factors for SCD
  2. h/o sudden cardiac arrest
  3. end stage HCM; LVEF <50%
  4. LV apical aneurysm
33
Q

what are the possible high-risk features for SCD?

A
  1. young age at diagnosis
  2. increased LVOT gradient
  3. myocardial ischemia
  4. genotype = troponin T and B-myosin heavy chain genes appear particularly malignant
  5. indicible arrhythmias

these all have really poor data and we aren’t actually sure if they put you at increased risk for SCD

34
Q

what is the treatment algorithm for HCM?

A
  1. high risk of SCD = ICD!!!
  2. if they have HF symptoms give verapamil, B-blockers or disopyramide to slow down HR and increase diastolic filling time
  3. if no symptoms of HCM, don’t give drugs
  4. if they have Afib, give anticoagulants and potentially cardioversion
  5. if they’re in end stage HF then give drugs to reduce after load like ACEI, ARBS, digoxin, BB, spironolactone

BB reduce risk of death after MI

35
Q

what patient population do you NOT give beta blockers to?

A

diabetics

BB mask the signs and symptoms of hypoglycemia!

also don’t give to COPD and asthma patients

don’t give to pheochromocytoma either

36
Q

what are the cons of ICDs?

A

25% experience an inappropriate ICD discharge

6-14% have complications like fracture, dislodgment or over sensing

it will shock anyone touching you too….

37
Q

which drugs are used to treat HCM?

A
  1. B-blockers = metoprolol, atenolol, propranolol
  2. non-dihydropyridine calcium channel blockers = verapamil
  3. ranolazine
  4. cautious use of diuretics because they’re preload dependent so if you’re in overt CHF then you have to give diuretics but otherwise don’t give them because diuretics decrease preload in patients who are preload dependent
38
Q

if you have pericarditis, JVD, muffled heart sounds and HTN, would you give a diuretic?

A

no

because they’re preload dependent because they have JVD = HF

39
Q

what’s the MOA behind the drugs given to treat HCM?

A
  1. negative inotropes to reduce LVOTO
  2. BB and CCB slow HR and prolong diastole which increases ventricular filling
  3. BB reduce angina symptoms by decreasing myocardial oxygen demand
  4. CCB may reduce angina symptoms by improving microvascular function
40
Q

what are the nonpharmacologic treatment options of left ventricular outflow tract obstruction?

A
  1. surgical myectomy of septal tissue and fix mitral valve
  2. alcohol ablation

used if pharmacologic therapy failures and HF symptoms persist despite maximal doses

both have similar efficacy but the need for a pacemaker after is higher in alcohol ablation

41
Q

what is alcohol ablation?

A

go in with a catheter through the coronary artery and burn and destroy tissue

just be careful about heart block

42
Q

what are the sports restrictions of HCM?

A

you can’t play if you’re diagnosed with HCM!!!

43
Q

an 18 year old male with HCM comes to the clinic for chest pain and tachycardia. he reports that he’s been drinking 5 energy drinks a day over the last few weeks. on exam he’s noted to have a heart rate of 130. what effect would you expect his tachycardia to have on his murmur?

A

the increased HR would lead to decreased preload making the murmur louder

44
Q

what is the most common cause of death from HCM?

A

underlying myocardial disarray and fibrosis causing a ventricular arrhythmias leading to loss of cardiac function

this is sudden cardiac death basically!

Cardio Week 4 (16 decks)

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