Cardiomyopathy Flashcards
What can cardiomyopathies cause?
Heart failure, arrhythmia, or maybe asymptomatic
What are some forms of cardiomyopathies?
- Dilated
- Hypertrophic
- Restrictive
- Arrythmogenic RV
5 LV non-compaction
T or F: Arrhythmogenic right ventricular cardiomyopathy is genetically distinct from other myopathies
T: Arrhythmogenic right ventricular cardiomyopathy appears to be a genetically distinct category, although its clinical phenotype cannot always be easily distinguished from that of dilated cardiomyopathy.
What is impaired in dilated cardiomyopathy?
Impaired contraction of one or both ventricles
LV ejection fraction < 40%
What is dilated cardiomyopathy a result of?
Results from myocyte death and replacement fibrosis from mutations that reduces heart contractility
T or F: coronary arteries are implicated in DC?
F
What are some causes of DC?
- Idiopathic: most common, often genetic (>40 disease genes–abnormalities of cytoskeletal/contractile proteins)
Peripartum cardiomyopathy - Inflammatory/infectious
Viral myocarditis, HIV, Chagas’ disease, Lyme disease
Rheumatic heart disease
Connective tissue diseases (systemic lupus erythematosus) - Toxic/metabolic
Alcohol, cocaine, anabolic steroids
Adriamycin (and other chemotherapy)
Diabetes, thyroid disorders - Neuromuscular disorders
- Tachycardia-induced
- Infiltrative
Hemochromatosis—iron deposition
Sarcoidosis
What are some symptoms of DC?
- Shortness of breath because of high LV diastolic pressure
- Fatigue because of decreased cardiac output
- Peripheral edema because of increased RA pressure
- Occasionally angina because of increased LV wall tension which results in increased myocardial oxygen demand
- Syncope and palpitations because of arrhythmias
What are some physical exam findings of DC?
Tachycardia, BP may be low
Enlarged apical impulse
JVP may be elevated
Third heart sound (volume overload)
Murmur of mitral regurgitation may be present
Dilated LV with lack of coaptation of mitral leaflets results in functional (secondary) mitral regurgitation
What is the most accurate diagnostic tool for DC and what does it show?
Cardiac MRI
Tissue characterization: edema, fibrosis, infarction
What can an electrocardiogram show for DC?
Dilated, spherical left ventricle with ejection fraction < 40%
What does an ECG tell about DC?
Left ventricular hypertrophy
Conduction abnormalities
What are some complications of DC?
Arrhythmias:
- Atrial fibrillation/flutter (distension of left atrium because of increased LA pressure)
- Ventricular (ventricular fibrillation and ventricular tachycardia)
Mitral regurgitation (secondary to increased LV sphericity)
LV thrombus and stroke
Progressive heart failure
What is the therapy for DC?
Life prolonging therapies:
- ACE inhibitors or ARBs
- Beta-blockers
- Spironolactone
- Valsartan/sacubitril (Entresto)
Diuretics as necessary for fluid retention
Cardiac resynchronization if left bundle branch block, EF <35% and NYHA class II-IV
LV assist device or cardiac transplant if NYHA class III-I
What happens to the heart in hypertrophic cardiomyopathy?
Left ventricular hypertrophy with myocardial fiber disarray (wall thickness > 15 mm) and interstitial fibrosis:
- Asymmetric septal hypertrophy most common (septal/posterior wall thickness > 1.5)
- Concentric hypertrophy
- Apical hypertrophy
What is the molecular cause of HC?
Disease of the sarcomere: Abnormalities in beta-myosin heavy chain, troponin T, tropomyosin
T or F: in HC the intramural vessels’ lumen become narrowed and may exhibit ischemia
T
Why is there a LVOT obstruction during systole in HC?
As blood flow accelerates through the narrowed
LV outflow tract, Venturi forces pull the anterior
mitral leaflet into the LVOT and create a dynamic
LVOT obstruction and mitral regurgitation
(loud systolic murmur)
T or F: EF is reduced in HC
False: higher than 50%
What’s diastolic dysfunction?
Decreased relaxation
Increased stiffness
What are symptoms of HC?
- Angina: Inadequate coronary arterial blood supply for degree of hypertrophy
- Dyspnea: High LV diastolic pressure because of impaired LV relaxation and increased stiffness
- Syncope: Arrhythmias or hypotension
- Sudden cardiac death: Ventricular fibrillation
- -> May be asymptomatic (caught via imaging)
What are some physical exam signs of HC?
Spike and dome carotid pulse
- Fourth heart sound (increased filling with atrial contraction because of decreased LV relaxation)
- Triple ripple apical impulse (two systolic impulses and palpable S4)
- Systolic ejection murmur from LV outflow tract obstruction
- Louder murmur if decreased preload (e.g. standing from a squatting position)
- Murmur of mitral regurgitation
How to do diagnose HC?
- Echocardiogram shows left ventricular hypertrophy in the absence of hypertension or aortic stenosis
- Cardiac MRI: Degree of fibrosis predicts arrhythmias
- ECG: Usually abnormal
- –> Left ventricular hypertrophy
- Family history going back 3 generations/genetic testing
What’s a variant of HC?
Apical hypertrophy
What usually results in apical hypertrophy?
May lead to LV apical aneurysm
Ventricular tachycardia
Thrombus formation and stroke
What characteristic is found on the ECG for apical hypertrophy?
Giant negative T waves
How to manage HC?
Improve symptoms:
- Dynamic LVOT obstruction
- –> Medical therapy: Beta-blockers, verapamil, disopyramide
- –> Surgery: septal myomectomy or septal alcohol ablation
Prevent death from ventricular arrhythmias with implantable defibrillator if: very thick septum (>30 mm) ventricular tachycardia unexplained syncope family history Drop in BP with exercise
Is restrictive cardiomyopathy common?
NO
What happens RC?
- Stiff ventricles because of fibrosis or infiltrative disorder
- Normal systolic function
- Severe diastolic dysfunction
What kind of dysfunction occurs in RC?
With diastolic dysfunction, the LV fills at a lower volume and higher pressure
What are the causes of RC?
1) Amyloidosis: abnormal protein deposition in myocardium—may be associated with multiple myeloma or ATTR (transthyretin amyloid)
2) Endocardial fibroelastosis
3) Hypereosinophilic syndrome
What are some signs and symptoms?
Increased LV/RV diastolic pressures:
- Jugular venous distension
- Hepatomegaly
- Ascites
- Edema (peripheral and pulmonary)
Low cardiac output:
Weakness
Fatigue
What are the management practices for RC?
Diuretics—judicious use to prevent hypotension
Avoid vasodilators
Treatment of underlying systemic condition
Occasionally, cardiac transplant
What causes Arrhythmogenic RV cardiomyopathy?
Often due to mutations in cell adhesion genes –5 genes which encode for desmosomal proteins
What happens in Arrhythmogenic RV cardiomyopathy?
Fibro-fatty infiltration of RV free wall:
- Regional RV dysfunction
- Ventricular arrhythmias, right heart failure
What occurs in LV non-compaction?
Intrauterine arrest of LV compaction of trabecula muscles
What may happen in LV non-compaction?
LV systolic dysfunction, arrhythmias and thromboemboli
