cardiomyopathy (see DM) Flashcards
what is a cardiomyopathy
a disorder in which heart muscle is structurally and functionally abnormal
what are the 2 common types of cardiomyopathies
hypertrophic cardiomyopathy; dilated cardiomyopathy
what are the 2 less common types of cardiomyopathies
arrythmogenic right ventricular cardiomyopathy; restrictive cardiomyopathy
what is hypertrophic cardiomyopathy
unexplained hypertrophy, most often affecting the wall between two ventricles; diastolic abnormality; usually asymmetrical (symmetrical may be due to AS/MR); bulges into LV overflow tract
what is dilated cardiomyopathy
stretching and weakening of the heart muscle, usually starts in the LV; systolic abnormality
what is arrythmogenic right ventricular cardiomyopathy
an inherited disease where fat and scar tissue (fibrofatty tissue) replace muscle in the right ventricle
what is restrictive cardiomyopathy
stiffening of the ventricle walls
what is the commonest cause of sudden cardiac death in <35yro
hypertrophic cardiomyopathy
what kind of dominance does HCM have
autosomal dominant mutations in genes that code for sarcomere components
brief pathophys of HCM
mutant peptides incorporated into sarcomere -> bad contraction -> hypertrophy to compensate
muscle cell organisation in HCM
disarray; hypertrophied
what is hypertrophic obstructuve cardiomyopathy (HOCM)
obstructive form of HCM where the outflow tract is blocked due to the anterior leaflet of the MV veing dragged over towards the lateral wall, blocking the outflow of blood from the LV; leads to MR and irregular/jumping pulse
myofibre disarray pathway to symptoms
myofibre disarray -> ventricular arrhythmias e.g. re-entry due to hypertrophic cells having diff electrical properties -> syncope, sudden death
LVH to symptom pathway (2)
- LVH ->impaired relaxation -> increased LVEDP -> SOB;
- LVH -> increased myocardial O2 demand -> chest pain
LV outflow obstruction to symptom pathway (3)
- obstruciton -> incr systolic pressure -> incr 02 myocardial demand -> chest pain;
- obstruciton -> mitral regurg -> SOB
- obstruciton -> failure to incr CO during exertion -> syncope
4 main parts to management of HCM
- education and reassurance;
- risk stratification for sudden cardiac death;
- management of symptoms and complications;
- family screening
when is an ICD recommended for HCM
of there has been a prior CVD event e.g. sustained VT
what drug is given for HCM
BBs or verapamil - decr HR and force of contraction -> incr diastolic filling time, decr myocardial O2 demand
what is mavacamten
a targeted inhibitor of cardiac myosin (reduces cross bridges) that improves symptoms in HOCM
what are 2 main complications o HCM and how are they managed
- AF - often poorly tolerated due to loss of atrial contribution to diastolic filling, anticoagulate, rate/rhythm control;
- HF - drugs or myomectomy improve symptoms, if refractory HF symptoms refer for transplant
what should be offered to first degree relatives
genetic counselling; cascade family screening; regular ECG and echo (if no mutation found)
4 compensatory mechs of dilated cardiomyopathy
neurohormonal activation; sympathetic nervse upregulated; ADH release; RAAS downreg
brief pathophys of dilated cardio myopathy (3)
- myocyte injury -> decr contractility -> decr SV -> incr ventricular filling pressure -> pulmonary congestion + systemic congestion;
- myocyte injury -> decr contractility -> decr SV -> LV dilation -> mitral regur -> LV dilation etc.
- myocyte injury -> decr contractility -> decr SV -> decr forward CO
6 main causes of DCM
- idiopathic
- genetic (familial, neuromuscular)
- inflammatory (infectious, non infectious)
- toxic
- metabolic
- tachy induces (arryhtmias)
