11/14 Cardiomyopathies - Almendral Flashcards
cardiomyopathy
categories
disease of heart muscle in which muscle is structurally and functionally abnormal
- often genetic
- can be isolated or part of a systemic disease
- NOT due to CAD, HTN, or valve disease
five types/categories based on appearance and physiology:
- dilated CM
- hypertrophic CM
- restrictive CM
- arrhythmogenic RV CM
- unclassified
dilated CM
etiologies (6)
idiopathic
familial (genetic)
inflammatory
- infectious (viral)
- non infectious (connective tissue, peripartium, sarcoidosis)
toxins
- chronic alcohol
- chemotherapeutic
metabolic
- hypothyroidism
- chronic hypocalcemia
- chronic hypophosphatemia
neuromuscular
- muscular or myotonic dystrophy
causes of DCM: viral myocarditis
ex. Coxsackie grp B, parvovirus B19, adenovirus, others
immune mediated → leads to myocyte loss and fibrosis
- usually self limited but can lead to DCM
tx: supporting care, routine HF meds
causes of DCM: toxins
chronic alcohol consumption
- high consumption for several years → causes ox stress, apoptosis, impaired bioenergetics, decr myocardial protein synth
- reversible if early
chemotherapeutic agents
- anthracyclines (other agents also implicated)
- acute or chronic (cumulative dose dependent)
- effects: free radical formation, direct cell apoptosis
causes of DCM: peripartium CM
- HF toward end of pregnancy or in months after delivery without any identifiable cause
- multifactorial causes
- incr exidative stress
- impaired VGEF signaling
- altered prolactin processing
- tx: routine HF meds, bromocriptine is promising
over half recover in 6mo
causes of DCM: familial CM
up to 50% of CM previously termed ‘idiopathic CM’ is likely familiat
>40 gene mutations identified
- atudo dom: 90%
- X-linked, recessive: 10%
- variable penetrance, variable expressivity
tx of HF due to DCM
routine HF medications: diuretics, ACEI, ARB, beta blockers, aldosterone antagonists
1/3 improve spontaneously or with meds
hypertrophic CM
- hypertrophic obstructive CM
- idiopathic hypertrophic subaortic stenosis
genetic disease → myocardial disarray
- auto dom with variable penetrance
- due to mutations in one of several sarcomeric genes
- beta myosin heavy chain
- cardiac troponins
- myosin binding proteins
- titin, cardiac actin, myosin binding protein C
- incr collagen matrix with interstitial and replacement fibrosis
signs/symptoms
- asymmetric LVH (sometimes global)
- commonly presents in adolescence
- majority have few or no sx
- prone to arrhythmias due to fibrosis
- majority have normal lie expectancy
- most common cause of sudden cardiac death
HCM variants
most common?
asymmetric septal hypertrophy (90%)
LVOT obstruction in HCM
25% of hypertrophic CM patients have LVOT obstruction at rest
- worse with decr LV cavity size
- worse with incr contractility
in both cases, walls are coming closer and closer together → obstruction!
clinical presentation of HCM
dyspnea on exertion, SOB from diastolic HF
angina
syncope
- arrythmias
- exertional: wose obstruction with incr contractility
atrial fibrillation
VT/VF arrest (sudden cardiac death): young athletes
clinical findings of HCM
mild forms? could have normal findings
typical HF findings
S4: atrial contraction into stiff LV
if LVOT is present…
- systolic diamond shaped murmur LPSB (left posterior subdivisional block)
- apical holosystolic murmur from MR
when is hypertrophic CM LVOT obstruction worst?
- decr preload : dehydration
- decr afterload : vasodilator (alcohol, hot tub, PDE5 inhibitor)
- incr contractility : vigorous exercise
HCM diagnostic studies
EKG
- LVH, left atrial enlargement
- Q waves in inferior, lateral leads
- diffuse T wave inversions
- a fib, ventricular arrhythmias
echo
- ID and measurement of LVH
- determine presence of obstruction
- measure gradient
cath
- measure resting/provocable gradient
treatment of HCM
beta blockers
non-dihydropyridine Ca channel blockers (verapamil)
disopyramide (1a antiarrhythmic)
- reduce contractility → reduce obstruction → reduce oxygen demand
- decr ectopy
- decr HR → incr diastolic filling time
avoid diuretics, vasodilators
- dihydropyridine Ca channel blockers, ACEI/ARBs, nitro
refractory cases that are OBSTRUCTIVE:
- alcohol septal ablation
- septal myomectomy
AICD for high risk patients
pathophys of RCM
3 findings and their effects
- incr muscle stiffness → decr compliance
- incr filling pressures → incr systemic/pulmonary venous pressure
* usually affects both RV and LV! → R and L side volume overload - decr cavity size → decr SV → decr CO
also see congestion and low output failure
- usually R-sided (vs L-sided)
unclassified CM
1. LV non-compaction
- genetic: auto dom, but also cases that are recessive and X-linked
- results in arrested devpt of myocardial compaction during fetal growth
- see deep intra-trabecular recesses
- sx: heart failure, thromboembolism, VT/VF
2. stress-induced CM
- Takotsubo CM aka broken heart syndrome
- precipitated by emotional or physical stress
- see transient apical or mid-LV ballooning
- chest pain, diffuse T-wave insertions, + troponing
- LV fx normalizes over days or weeks
