Fifteen Flashcards
What is the cause of hypertrophic cardiomyopathy? What 4 genes are usually involved?
- 100% genetic cause !!
- Familial in ~ 55% of cases with autosomal dominant transmission
- Mutations in one of 4 genes encoding proteins of cardiac
sarcomere account for majority of familial cases:
- -MHC
- cardiac troponin T
- myosin binding protein C
- -tropomyosin
Remainder are spontaneous mutations.
What are the pathologic manifesations of HCM?
Myocyte hypertrophy, interstitial fibrosis, myocyte disarray, and small vessel disease.
Generally, at least 1/3 of myocardium is involved.
What causes the left ventricular hypertrophy? What are the different kinds? What kind of dysfunciton is there?
Not due to pressure overload (phenotypically and genetically different).
Hypertrophy is variable in severity and location:
Asymmetric septal hypertrophy (most common)
Symmetric (non-obstructive)
apical hypertrophy
- Vigorous systolic function, but impaired diastolic function
- impaired relaxation of ventricles
- elevated diastolic pressures
What is HOCM? What symptoms are there and where do they come from?
Dynamic LV outflow tract obstruction (may be present at rest or exertion in ~ 33%) – IF SO, WE CALL HOCM!!! – no longer just HCM
o SAM (systolic anterior motion of mitral valve)
o LVOT Obstruction–> LVOT gradient > incr. wall stress > incr. MVO2 >ischemia/angina
o incr. LVOT gradient: incr. HR (reduced DFP), decr. preload (LVEDV), decr. afterload(BP).
o decr. LVOT gradient: incr. BP (Afterload), incr. LVEDV(preload)
- Symptoms of dyspnea and angina more related to diastolic dysfunction or increased myocardial demand from severe hypertrophy than to outflow tract obstruction.
- Syncope from LVOT obstruction !! (failure to increase CO during exercise or after vasodilatory stress)
or arrhythmia [especially atrial fibrillation]. Need to make sure not ventricular arrhythmia though….
What are some symptoms of myocyte hypertrophy and what do they lead to? Same question for dynamic LV Outflow obstruction?
Hypertrophy: myofibers in disarray–>ventr. arrhythmias=syncope or sudden death. Also LVH leads to impaired relaxation leading to increased LVEDP leading to dyspnea. LVH also leads to increased MVO2 which leads to angina.
Obstruction leads to increased systolic pressure which leads to increased MVO2 leading to angina. It also leads to MR which leaeds to dyspnea. It also leads to a failure to increase CO with exertion leading to syncope.
What are some signs for HOCM in the physical exam? What is the murmur like? How does it change with valsalva maneuver, squatting, and standing compared to AS?
Physical Exam in HOCM
- Bisferiens (double) pulse
- S4 gallop
- Crescendo-Descrescendo systolic ejection murmur that changes with certain maneuvers
HOCM vs. Valvular Aortic Stenosis Intensity of murmur
HOCM (AS is opposite on all 3 maneuvers)
Valsalva (decr. preload, decr. afterload)-increase murmur
Squatting (incr. preload, incr. afterload) Decr. murmur
Standing ( decr. preload,decr. afterload) incr. murmur
- Holosystolic apical b
blowing murmur of mitral
regurgitation
How does the magnitude of hypertrophy related to risk of death?
It is directly correlated to risk of sudden death. Even without symptoms, extreme hypertrophy greately increases risk.
What are some adverse predictors with HOCM?
Predictors of adverse prognosis:
Early age of diagnosis
Familial form with sudden death in 1st degree relative [often has mutation of beta-MHC gene]
History of syncope
Ischemia/chest pain on exertion
Presence of ventricular arrhythmias on ambulatory monitor
How is HOCM treated?
- Beta-blockers, calcium channel blockers, disopyramide
- AVOID DIURETICS/VOLUME DEPLETION – worsens obstruction and gradient
- Alcohol Septal Ablation
- Surgical myectomy
- Implantable defibrillator
What is restrictive cardiomyopathy? Describe the pathophys a little.
Hallmark is impaired ventricular filling with preserved systolic function from FIBROSIS/SCARRING or INFILTRATION BY SYSTEMIC DISEASE
– Systolic dysfunction is common in end-stage RCM; otherwise systolic function usually preserved.
– Physiologically the LV fills to its normal end-diastolic volume only at elevated LVEDP (very non-compliant).
–Secondary diastolic HF may exhibit restrictive physiology but ARE NOT TRUE RESTRICTIVE CARDIOMYOPATHIES. Secondary ventricular hypertrophy and fibrosis due to excessive pre-load
(renal failure) or after-load (HTN).
How do patients present with RCM and what are some symptoms?
Patients present with congestion and low output symptoms (CHF!!!!):
More right-sided failure symptoms than in systolic heart failure.
- Exercise intolerance (tachycardia compromises ventricular filling)
- Dyspnea
- PND
- Orthopnea
- Fatigue
- Edema
- Ascites
- Angina
What are some important causes of RCM?
Idiopathic CM, Amyloidosis, Sarcoidosis, some LSDs, Hemochromatosis, Endomyocardial fibrosis, etc.
Decribe primary and secondary amyloidosis.
Primary-Deposition of amyloid fibrils. Immunoglobulin light chains (AL)-Multiple myeloma. Heart failure is one of the most common cuases of death in this disease.
Secondary-Deposition of proteins other than immunoglobulin: Chronic inflammatory processes (AA protein): rheum. athr.; Familial/Hereditary-Transthyretin (AD); Senile-transthyretin in elderly, benign.
What is sarcoidosis? What effects does it have in RCM?
Autoimmune-mediated infiltration of inflammatory non caseating granulomas.
Restrictive diastolic filling, conduction system disease (heart block), and ventricular arrythmias
Hemochromatosis
Excess iron deposition leading to heart enlargement and failure (RCM)
