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Hypertrophic cardiomyopathy
Dipin.s
Junior resident
Internal medicine
• Autosomal dominant disease of the heart
muscle, characterized by a small left ventricular
cavity and marked hypertrophy of the
myocardium with myofibril disarray.
• Overall prevalence is 1:500 to 1:1000
• Disease of the myofilaments, with alteration in
structure and function
• Most common cause of sudden cardiac death in
young people.
• Asymmetric septal hypertrophy (ASH)
• Idiopathic hypertrophic subaortic stenosis
(IHSS)
• Muscle subaortic stenosis
• Hypertrophic obstructive cardiomyopathy
(HOCM).
Etiology
• Most common genetic cardiovascular disease
• Mutation in genes encoding proteins of the
cardiac sarcomere myofilaments
• Beta-myosin heavy chain, myosin-binding protein
C, cardiac troponin T and I,alpha -tropomyosin,
actin, titin, and myosin light chains
• Other genes outside of the sarcomere
myofilaments have also been recently implicated
• Deletions, insertions, missense, and splice site
mutations.
• Hypothesis is that sarcomeric dysfunction
leads to compensatory hypertrophy.
pathology
• Asymmetrical hypertrophy with a small LV
cavity
• Mural endocardium thickened by fibrous
tissue
• Elongation of chordae and ant. displacement
of the hypertrophied papillary muscles
• LA is usually dilated
Histology
• Short runs of severely hypertrophied fibers
interrupted by connective tissue
• Large and bizarre nuclei and fibrosis , with
degenerating muscle fibers.
• Whorling of muscle fibers is characteristic of
HCM
Pathophysiology
Diastolic dysfunction
• Impaired ventricular relaxation and chamber
stiffness
• Compensatory increase in late diastolic filling by
atrial systole.
• During exercise or any other type of
catecholamine stimulation, diastolic filling period
decreases as well as myocardial ischemia occurs
• Leads to severe diastolic dysfunction- dyspnoea
LVOT obstruction
• Multifactorial
• During systolic contraction the hypertrophied
basal septum encroaches to the outflow tract
• Mitral leaflets are pulled in by the venturi
force
• In midcavitary region hypertrophied pappillary
muscles pressing against septum may cause
obstruction
• LVOT obstruction is dynamic
• Increased myocardial contractility, decreased
ventricular volume, or decreased afterload
----increases
Myocardial ischaemia
• Supply-demand mismatch
• compromised coronary blood flow to the LV
myocardium -- abnormally small and partially
obliterated intramural coronary arteries
Autonomic dysfunction
• Either a failure of systolic blood pressure to
rise >20 mmHg or a fall in systolic blood
pressure during excercise.
• Speculated that there is high degree of
abnormal autonomic tone in HCM
• Assoc. with poor prognosis
Mitral regurgitation
• Secondary phenomenon due to systolic
anterior motion of leaflets due to LVOT
obstruction
• During mid and late systole- jet directed post.
and laterally
Clinical presentation
• Most are asymptomatic
• Dyspnoea-diastolic dysfunction and elevated
LV filling pressures
• Angina – epicardial coronary disease may be
absent
• Syncope or presyncope- LV baroreceptors
causes reflex vasodilatation
• Atrial fibrillation occurs more in elderly
Physical examination
• Carotid pulse- spike and dome pattern
rapid rise (percussion wave)
midsystolic drop
secondary wave (tidal wave)
• Jugular venous pressue- usually normal;
sometimes prominent a wave (hypertrophy
and lack of compliant RV and powerful Rt
atrial contraction)
• Apical impulse- forceful, sustained, diffuse
double or triple apical impulse
(outward thrust of ventricular contraction,
a presystolic accentuated atrial contraction, and
expansion of early diastolic filling)
• Cardiac sounds- usually split sometimes
paradoxically split
S4 if severe hypertrophy
• Murmurs =crescendo–decrescendo murmur
located primarily at the left sternal border.
(usually ends before S2)
• May radiate to the base or apex, but seldom
radiation to the carotid arteries.
• Any condition which increases the LVOT
outflow gradient – more obstruction –
murmur is louder longer and peak late in
systole
LVOT obstruction and systolic murmur
increased by……….
• A reduction in LV cavity volume and pressure
( less preload)
• A decrease in systemic vascular resistance /
arterial pressure ( less after load )
• An increase in LV contractility
• Converse is also true
Anterior Mitral
Leaflet
Myocardial Contractility
Exercise
Cathecolamines
Digitalis
Ventricular Volume
Valsalva
Standing
Nitroglycerine
Tachycardia
Gradient / Murmur
Per Arterial Pressure
Methoxamine
Sustained Handgrip
Passive Leg Raise
BV Expansion
Gradient / Murmur
ECG
•
•
•
•
Abnormal in 90-95 % patients
LVH
LAE
Deep and narrow q waves in inferolateral
leads
• Diminished R waves in lateral precordial leads
• Large negative precordial T waves
• Left axis deviation
• No ECG finding is predictive of future events
• Tall R and deep S waves weakly corelated with
magnitude of LV hypertrophy
•
•
•
•
SVT 46%
PVCs 43%
Non sustained VT 26%
AF can occur in 25-30% of elderly
Chest X-Ray
• Mild to moderate enlargement of the cardiac
silhouette.
• The left ventricular contour is rounded
consistent with concentric LVH.
• Enlargement of the left atrium
• Right-sided chambers are usually normal.
Echocardiography
• Gold standard for the diagnosis of HCM
• Increased wall thickness in the absence of other
etiology
• Septum>=1.3 times LV post.free wall
• Subaortic Gradient > 30mm Hg ( rest)
>50(provocation)
• Vigorous motion of post. Free wall with reduced septal
excursion
• Avg. LV wall thickness in HCM is 20- 22mm
• ECG and echo has to be correlated.
• Low voltages in ECG in the presence of increased wall
thickness is seen in infiltrative disorder
• Small LV cavity/ Septal immobility
• Primary tool for defining the presence and
severity of LVO tract obstruction
• Systolic anterior motion of mitral valve
• Presence and severity of MR
(laterally and posteriorly directed jet in mid to
late systole)
Cardiac MRI
• Subaortic gradient >30 is a determinant of
heart failure but risk of sudden death
• Elderly patients are not targeted for risk
stratification(SCD is uncommon and survival to
old age itself suggests low risk)
• Beta myosin heavy chain and trop T mutations
are assoc. with higher risk for premature
death.
Management
Prevention of SCD
• ICD implantation – as primary prevention
following cardiac arrest
-as secondary prevention if
one or more high risk factors
• Empirical pharmacological therapy with
amiodarone is now obsolete
Medical treatment
Heart failure
• Beta blockers (slows heart rate, reduce force of LV
contraction, augments ventricular filling and
relaxation, decreases myocardial O2 demand,
blunts outflow gradient triggered by sympathetic
activity)
• Verapamil (improves LV relaxation and filling)
• Disopyramide
• End stage failure –ACE ,ARBs, ICD to prevent SCD
• Atrial fibrillation- most common sustained
arrhythmia in HCM
• Paroxysmal AF occurs in 20%
• Increases with age and is related to LA dilatation
• Acute decompensation- cardioversion
• Amiodarone prevents reccurences
• Rate control with beta blockers or verapamil
• Started on anticoagulation
Diuretics……………..
• Can be use alone judiciously or with
betablockers / verapamil to lessen pulmonary
congestion
Non medical treatment
Surgery
• Severe drug refractory heart failure symptoms
• Severe functional disability (NYHA class III , IV)
• Associated with LV outflow obstruction at rest
or with physiological exercise (>50mm
gradient)
• Transaortic ventricular septal myectomy
(morrow procedure)-small portion from basal
septum
Alcohol ablation
• 96-98 % ethanol (1-3 ml)introduced into major septal
perforator vessel
• Necrosis and permanent MI in proximal septum is
created
• Thinning and reduced excursion of septum, Outflow
tract enlarges- reduction of subaortic obstruction and
MR
• alternative treatment strategy for selected patients—
(advanced age, significant comorbidity and increased
operative risk, without access to expert surgical
centers, or pt.against surgical intervention)
Alcohol ablation
• Dual chamber pacing – no definite evidence
Infective endocarditis
• Vegetations most commonly seen on anterior
mitral leaflet or septal endocardium at the site
of mitral valve–septum contact
• standard antimicrobial prophylaxis is
indicated prior to dental or surgical
procedures
Thank you