Cardiomyopathies

Question 1

Hypertrophic Cardiomyopathy (HCM)

or HOCM (70% are obstructive)

Answer 1

CURRENT pp. 247-251

essentials of diagnosis:

• dyspnea, CP, syncope
• though LV outflow gradient is classic, sxs are primarily related to distolic dysfunction
• echocardiogram is diagnostic
• increased risk of sudden death (most common cause of sudden death in athletes)

Diagnostic features:

• genetic mutation (inherited autosomal dominant) OR sporadic occurence
  
  • mutation of genes that code for myosin heavy chains regulating Ca handling
• myocardial fiber disarray
• asymmetric LV hypertrophy
• LV outflow obstruction
  
  • (LV outflow tract is narrowed during systole due to hypertrophic septum and systolic anterior motion of the mitral valve) (obstruction worsened by factors that increase myocardial contractility (ie sympathetic stim, digoxin, postextrasystolic beat) or that decreased LV filling (ie Valsalva manuever, peripheral vasodilators))
  • amount of obstruction is preload and afterload dependent and can vary frmo day to day)

HCM noted when there is LV hypertrophy unrelated to any pressure of vol overlead (ie no underlying cause).

Hypertrophy reduces LV systolic stress, increases EF, and can result in an “empty ventricle” at end of systole.

consequence = elevated LV diastolic pressures not systolc

LV usually more involved than RV and atria are frequently significantly enlarged

Epidemiology:

• pt usually present in early adulthood, sxs anifest around puberty
• healthy appearing young men
• can occur in elderly

S:

• dyspnea and chest pain
• syncope also common
  
  • typically postexertional, when diastolic filling diminshes and outflow obstruction increases due to residual circulating catecholamines
• arrhythmias are important problem (A-fib and ventricular [sudden death in athletes may occur after extraordinary exertion])

O:

• PE: bisferiens carotid pulse, triple apical impulse (due to prominent atrial filling wave and early and late systolic impulses), and loud S4
  
  • JVP may reveal prominent a wave due to reduced RV compliance
  • loud systolic murmur (in cases with outflow obstruction) along LSB that increases with upright position or Valsalva and decreases with squatting
    
    • *murmur helps distinguish b/n aortic stenosis, since in HOCM, reducing LV vol increases obstruction and murmur intensity where in aortic stenosis, reducing stroke vol across valve decreases the murmur (milk jug)

A/P:

• ECG (25% are normal); exaggerated septal Q waves may mimic MI
• Chest XR often unimpressive
• echocardiogram is diagnostic: revealing asymmetric LVH, systolic anterior motion of the mitral valve, early closing followed by reopening of aortic valve, small and hypercontractile LV, delayed relaxation and filling of LV during diastole
  
  • septum usually 1.3-1.5cm times thickness of posterior wall; septal motion reduced
  • doppler sounds reveal turbulent flow and dynamic gradient in LV outflow tract and commonly mitral regurg
  • 80% of patients show abnormalities in diastolic filling patterns
• Cardiac MRI confirms hypertrophy and contrast can reveal evidence of scar at junction of RV attachment to septum
• Cardiac Cath confirms DX and defines presence of CAD or not
• exercise studies recommended to assess for ventricular arrythmias and to document BP response
• TX:
  
  • Beta blockers should be initial drug in sx pts, especially when dynamic outflow obstruction is noted on echo (resulting slower HR assists w/ diastolic filling of stiff LV)
  • Ca channel blockers (verapamil especially) effective in sx pts (effect due to improved diastolic function but vasodilating actions can also increase outflow obstruuction and cause hypotension)
  • Disopyramide (not first line tx usually in addn, or to treat arrythmias)
  • Diuretics (freq necessary due to high diastolic pressure and PCWP)
  • implantable defibrillator (in pts with ventricular arrythmias and fam h/o sudden cardiac death on exercise)
  • septal myotomy/myectomy and nonsurgical septal ablation to reduce dynamis systolic LV outflow obstruction
  • refer to cardiologist! esp when have syncope, difficult to manage, or have high-risk features

**FYI***

Valsalva

phase 1: aortic compression => increase aortic P, low HR [reflex bradycardia]

phase 2: venal caval compression =>decreased VR=>decreased CO and aortic pressure, HR increases

phase 3: breathing resumes, no more aortic compression=> transient decrease aortic pressure and HR increase further

phase 4: VR increases, fast increase in COand increase in aortic pressure

Question 2

Dilated Cardiomyopathy

Answer 2

essentials of DX:

• sxs and signs of HF
• echo confirms LV dilation, thinning, and global dysfunction
• severity of RV dysfunction critical for long term

etiology:

• idiopathic
• ischemic: multiple infarcts
• toxins =
  
  • EtOH, uremia, adrimycin, Co
• major catecholamine d/c
• myocarditis* (viral)
• postpartum/peripartum
• doxorubicin (anticancer drug, cumulative cardiotoxicity)
• genetic dzs
• metabolic - DM, Beriberi
• arrythmogenic RV Dysplasia
• amyloidosis

pathology:
* genetic factors =>
* altered immune system => viral infection => myocarditis
* DNA mutation => altered myocardial function
* ventricles are markedly dilated
* heart appears to have flabby or thinned myocardium that is partially replaced w/ fibrous tissue
* **LV volume = decreased **
* EF = low
* diastolic failure

clinical manifestations:

• S:
  
  • L or biventricular HF (dyspnea most commonly) (wet [low CO-congestion] and cool [high PCWP-hypoperfusion])
• O:
  
  • cardiomegaly
  • S3
  • elevated JVP
  • **rales **
  • in severe HF = Cheyne-Stokes breathing, pulsus alternans, pallor, and cyanosis
    
    • clinical signs of HF:
      
      • pallor, cyanosis
      • tachycardia
      • tachypnea
      • distended neck veins
      • BP may be low
      • precordial heave
      • edema, ascites
      • hepatomegaly
    • auscultatory clinical signs of HF:
      
      • inspiratory rales
      • S3 and/or S4
      • holosystolic murmur
        
        • mitral regurg
        • tricuspid regurg

TX:

• diuretics
• inotropes = digoxin, dobutamine, milrinone (IV)
• ACE inhibitors
• ARBs
• Hydralazine/Nitrates (vasodilate)

Question 3

Tako-Tsubo Cardiomyopathy

Answer 3

etiology:

• LV apical ballooning following high catecholamine stress and d/c
• follows a stressful event ie hypoglycemia, lightning strikes, earthquakes, postventricular tachycardia, EtOH w/drawal, postop, hyperthyroidism, after stroke, following emotional stress
• “broken heart syndrome”

pathology:
* catecholamine release

clinical manifestations:

• S:
  
  • similar to acute coronary syndrome
  • typical angina
  • dyspnea
  • syncope is rare (arrythmias are not

TX:

• immediate therapy similar to MI
• long-term therapy if LV dysfunction persists
• ASA, beta-blockers, ACE inhibs until LV fully recovers

Question 4

Restrictive Cardiomyopathy

Question 5

Cardiomyopathies

Answer 5

• primarily affecting myocardium
• ass w/ major causes of heart disease ie:
  
  • ischemic heart disease
  • HTN
  • pericardial dz
  • valvular dz
  • congenital defects
• many causes are idiopathic