Cardiomiopatia ipertrofica Flashcards
epidemiologia
-Second most common cardiomyopathy
- Obstructive type/hypertrophic obstructive cardiomyopathy (HOCM): ∼ 70% of cases (di cui 50 % a riposo e 50 % con Valsalva)
- Nonobstructive type: ∼ 30% of cases
Alongside myocarditis, HCM is one of the most frequent causes of sudden cardiac death in young patients, especially young athletes.
Eziologia , most common hereditary heart disease: 60–70% of HCM cases
-50% è familiare!
!NO inotropi positivi
Primary HOCM: a genetic condition characterized by otherwise unexplained left ventricular hypertrophy.
-Autosomal dominant inheritance with varying penetrance (familial occurrence in > 50% of cases)
Most commonly due to mutations in genes encoding myosin heavy chain → causes disorganized myocyte architecture characterized by myofibrillar disarray and fibrosis
Less commonly due to a mutation in cardiac sarcomeric proteins such as troponin and tropomyosin
Secondary HCM: associated with certain conditions
-chronic hypertension
-Friedreich ataxia
-Fabry disease ( deficit alpha galattosidasi A, con accumulo di ceramide nell’endotelio di molti vasi, nell’epitelio di diversi organi, nelle cellule muscolari lisce
-distesie, da neuropatia periferica piccole fibre
amieliniche, burning pain
-Anhidrosis or hypohidrosis
-Nonspecific gastrointestinal disturbances
-Angiokeratomas (tipico a livello dello scroto)
-Corneal clouding
-Cataract
-Late symptoms
-Cardiomyopathy
-Cerebrovascular lesions (TIA and stroke)
-Fabry nephropathy (glomerulosclerosi, che è la principale causa di morte in questi pazienti)
Treatment: enzyme replacement therapy with α-galactosidase A)
-Malattia di Pompe (glicogenosi)g
-Noonan syndrome
-amyloidosis
Pressure related hypertrophy: Cardiac hypertrophy is caused by chronic pressure and volume overload.
Chronic hypertension → increased afterload → increased myocardial wall tension → changes in myocardial gene expression → sarcomeres laid down in parallel → increased left ventricular thickness → decreased left ventricular size → diastolic dysfunction
Fisiopatologia
1.Obstructive type (HOCM):
Greater hypertrophy of interventricular septum compared with the LV wall → obstruction of LV outflow
- Concentric hypertrophy: increased LV wall thickness and decreased LV size, as sarcomeres are added in parallel, strain trasverso in eco
- Caused by an increase in afterload, which can be due to chronic hypertension (most common), aortic stenosis, and HOCM
! During systole:
Accelerated blood flow through ventricular outflow tract causes negative pressure (Venturi effect) → anterior leaflet of the mitral valve is drawn against the septum (systolic anterior motion, SAM) → ↑ outflow tract obstruction, a cui può associarsi una insufficienza mitralica
Ejection flow pushes against abnormally placed and elongated MV leaflets → creates drag forces on a portion of the mitral valve leaflets → the leaflets are dragged into the outflow tract → ↑ outflow tract obstruction
Questo spiega perchè l’ostruzione al flusso è AUMENTATA in tutte quelle condizioni che diminuiscono il precarico a differenza di tutti gli altri vizi valvolari: il flusso stesso può ridurre il grado di avvicinamento del setto interventricolare con il lembo anteriore della mitrale
-ortostatismo brusco
-nitrati (tutte le condizioni che riducono pre e post carico)
-Valsalva
-inotropi positivi
Invece nelle condizioni di aumentato precarico e post carico il soffio sistolico si RIDUCE : clinostatismo, elevazione degli arti o posizione accovacciata o fenilefrina. (sono gli stessi principi di trattamento di un tamponamento cardiaco o di un infarto miocardico destro)
-Increasing mitral regurgitation : Severe SAM of the anterior leaflet causes a gap between the mitral leaflets through which a regurgitant jet flows.
-Obstruction is exacerbated by factors that lead to increased heart contraction force and cardiac output :
1.Physical exercise/stress
2.Reduction of preload or afterload (es. Nitroglicerina)
: reduction of afterload increases the pressure
gradient over the obstruction. In this situation, blood
can only be ejected at higher pressures, requiring
the heart to contract even more strongly.
3.Positive inotropic drugs (e.g., digoxin)
4.diuretici, idralazina
2.Nonobstructive type (33%) involves hypertrophy of the left (possibly also the right) ventricle resulting in:
Reduced diastolic compliance of the ventricle → reduced diastolic filling volume → reduced systolic output volume
Impaired cardiac contractility with reduced systolic output → reduced peripheral and myocardial perfusion (myocardial ischemia) → can cause disruption of electrical impulses → cardiac arrhythmia
Clinica
Symptoms: worsen with exercise, dehydration (riduce il precarico), and use of certain drugs (e.g., diuretics, hydralazine, ACEIs/ARBs, digoxin)
! Frequently asymptomatic (especially the nonobstructive type)
- Exertional dyspnea
- Angina pectoris
- Dizziness, lightheadedness, syncope
- Palpitations, cardiac arrhythmias
- Sudden cardiac death (particularly during or after intense physical activity)
Physical examination
- Systolic ejection murmur (crescendo-decrescendo)
- Increases with Valsalva maneuver, standing, inotropic drugs (e.g., digitalis)
-Decreases with:
Hand grip, squatting (aumenta il post carico), or passive leg elevation
Drugs that decrease cardiac contractility (e.g., beta blockers)
- Possible holosystolic murmur from mitral regurgitation
- Sustained apex beat
- S4 gallop (sovraccarico pressorio, onda a prominente in polso venoso giugulare)
- Paradoxical split of S2 (cioè si chiude prima la polmonare e dopo l’aortica, in espirazione non in inspirazione proprio perchè in inspirazione aumenta il precarico e diminuisce l’ostruzione. Si ricorda invece come tutti gli altri soffi associati ad altri vizi valvolari aumentino in inspirazione)
Pulsus bisferiens: LV outflow obstruction causes a sudden quick rise of the pulse followed by a slower longer rise (biphasic pulse). (lo ritrovimo anche nell’insufficienza aortica, mentre un polso parvus e tardo è tipico della stenosi aortica)
ECO
Findings
-Asymmetrically thickened left ventricular wall ≥ 15 mm (normalmente è 6-12 mm)
In obstructive type
-Asymmetrically thickened interventricular septum
-Systolic anterior motion: protrusion of the anterior mitral valve cusp towards the septum → dynamic obstruction of blood flow
! ↑ LVOT pressure gradient via doppler echocardiography (The gradient describes the difference in LV and aortic pressure. Values > 30 mm Hg are considered pathological. Some patients may have a pressure gradient > 50 mm Hg.)
-Provocation tests (see below) are obligatory if no obstruction is discernible at rest. (cioè è utile in quei soggetti che presentano la sintomatologia sotto sforzo)
ECG
- Can be normal!!
- Signs of left ventricular hypertrophy, “Sokolow-Lyon criteria”
- Possibly nonspecific ST-wave (sottoslivellamento) and/or T-wave changes (negative)
- Commonly in obstructive type: abnormally deep Q waves, particularly in the inferior (II, III, and aVF) and lateral (I, aVL, V4-6) leads
- Left bundle branch block (tipico roscontro anche della cardiomiopatia dilatativa)
- Ventricular tachycardia or atrial fibrillation
MRI
Cardiac MRI
- For evaluating ventricular morphology if echocardiographic results are ambiguous
- For detecting areas of fibrosis and necrosis
Cateterismo cardiaco
Cardiac catheterization including levocardiography.Shows increased diastolic filling pressure and an increased intraventricular pressure gradient.
Analisi genetica
Possibly genetic testing and/or pedigree analysis
Trattamento (Positive inotropic and afterload-reducing or preload-reducing drugs e.g., digitalis, glyceryl trinitrate, calcium channel blockers of the dihydropyridine class, ACEIs are contraindicated in patients with obstructive hypertrophic cardiomyopathy!)
- Medical therapy
- Beta blockers (first-line) or verapamil (second-line). La bradicardizzazioine favorisce il riempimento diastolico!
- Treat possible ventricular tachycardia or atrial fibrillation.
- Diuretics in nonobstructive HCM only
- Avoid diuretics in HOCM as well as digoxin and spironolactone in both types
- HOCM if symptoms persist despite nonsurgical treatment
- Cases of NYHA III/IV heart failure
- High-grade obstruction, gradiente transaortico (ventricolo-aortico) maggiore di 50 mmhg
Come agire?
- miomectomia settale (Morrow procedure)
- ablazione del setto con alchol (può causare blocchi di branca completi e richiedere successivo pacemaker)
- pacemaker cardiaco bicamerale (proposto anche in corso di cardiomiopatia dilatativa con LBBB)
ICD (in caso di forte rischio morte cardiaca improvvisa)
Le indicazioni sono le stesse per tutte le patologie cardiache che determinano importante insufficienza cardiaca con alterazione del FEVS (come cardiomiopatia dilatativa o AMI)
- FEVS minore del 35% con NYHA II/III e LBBB
- Main risk factors: sudden cardiac death in family medical history, documented non-persisting ventricular tachycardia, syncopes, hypotension on exertion (test da sforzo), thickness of left ventricle > 30 mm.
