Cardiomyopathy

BASIC Instructor & Provider Course, October 2008, Sydney. Registration deadline 27th September.
Click here for details

Dilated cardiomyopathy

Hypertrophic obstructive cardiomyopathy (HOCM)

Peripartum cardiomyopathy

Dilated cardiomyopathy

Pathophysiology

• impaired LV and/or RV systolic pump function leading to cardiac enlargement
• mural thrombi often present, particularly in LV apex

Pathology

• extensive area of interstitial and perivascular fibrois with minimal necrosis and cellular infiltration

• probably end result of myocardial damage due to a variety of toxic, metabolic or infective agents. None of these causes apparent in many patients
• in some patients may be the late sequel of acute viral myocarditis
• minority of patients have familial forms

• features of LVF and RVF
• arrhythmias
• some patients have LV dilatation for months or even years before becoming symptomatic
• vague chest pain may be present
• typical angina unusual and presence suggests concomitant IHD
• 3rd and 4th heart sounds common
• ± MR or TR
• diastolic murmurs, valvular calcification and severe hypertension reduce likelihood of cardiomyopathy
• systemic embolization common even in patients in sinus rhythm

• LV enlargement
• generalized cardiomegaly often seen. Sometimes due to concomitant pericardial effusion
• ± pulmonary venous hypertension, interstitial or alveolar oedema

• sinus tachycardia or AF
• ventricular arrhythmias
• LA enlargement
• diffuse non-specific ST-T wave abnormalities
• ± intraventricular conduction defects

• LV enlargement
• normal or minimally thickened or thinned LV walls
• pericardial effusion common

• may identify patients with dilated cardiomyopathy and concomitant myocarditis

• cardiac output does not increase normally with exercise
• LVEDP, LAP, PCWP elevated
• RVEDP and CVP also elevated when RVF develops
• angiography: dilated diffusely hypokinetic LV, often with some MR. Normal coronaries

• may be helpful in excluding conditions such as myocardial amyloid

• standard management of cardiac failure. ACE inhibitors improve survival
• anticoagulation in absence of contraindication
• avoid strenuous exercise
• some suggestion that cautious introduction of beta blockers may improve symptoms
• avoid anti-arrhythmics if possible because of pro-arrhythmic effects unless needed to treat symptomatic or serious arrhythmias

• patients who do not respond to medical therapy may benefit from dual chamber pacing with short AV interval with improvement in haemodynamics and symptoms
• benefits occur primarily in patients with prolonged PR interval
• results in reduced MR, increased LV filling and decreased ventricular wall stress
• should be considered as investigational at present

• consider for patients with advanced disease who are refractory to medical therapy and have no contraindications. (More on cardiac transplantation.)

Most patients deteriorate inexorably and the majority, particularly those > 55 years, die within 2 years of onset of symptoms. Death usually due to CCF or VT or bradyarrhythmia. Sudden death is a constant threat.

Hypertrophic cardiomyopathy

• hypertrophied muscle leads to diastolic dysfunction due to decreased ventricular compliance. Results primarily from an abnormality in calcium handling with attendant intracellular calcium overload
• heterogenous LVH, often with asymmetric septal hypertrophy: upper portion of septum is preferentially hypertrophied compared with posterobasal LV free wall
• dynamic LV outflow pressure gradient. Related to narrowing of subaortic area as a result of midsystolic apposition of anterior mitral valve leaflet against the hypertrophied septum (ie systolic anterior motion of mitral valve. Only 1/4 of patients have an outflow tract gradient
• three basic mechanisms are involved in production of dynamic pressure gradient: increased LV contractility (reduces LV systolic volume and increases ejection velocity of blood moving through the outflow tract, thus drawing the anterior leaflet against the septum as a result of reduced distending pressure), decreased preload (reduces further the size of the outflow tract) and decreased aortic impedance and pressure (increases velocity of flow through the subaortic area and also reduces LV systolic volume

• verapamil and diltiazem may reduce stiffness of ventricle, reduce elevated diastolic pressures, increase exercise tolerance and, in some cases, reduce the severity of outflow tract gradient

• has been used in some patients to decrease contractility and outflow gradient

• may be useful for patients refractory to medical therapy
• early results suggest that both symptoms and haemodynamic function can be improved if dual chamber pacing with short AV interval is used
• benefits thought to be due to reduced gradient across LV outflow tract. This is caused by pacing from the RV apex which creates a functional LBBB and paradoxical motion of interventricular septum

• myotomy or myectomy of hypertrophied septum may result in lasting symptomatic improvement in about 3/4 of operated patients
• mortality approx. 5%: limits operationto severely symptomatic patients with large pressure gradients who are unresponsive to medical management

• avoid drugs which increase contractility, or decrease afterload or preload
• endocarditis prophylaxis particularly in patients with resting obstruction and MR
• avoid strenous exercise in all patients regardless of symptoms: sudden death often occurs during or just after physical exertion

• natural history variable
• many patients demonstrate improvement or stabilization of symptoms with time
• AF common late in course of disease: onset may lead to an increase in symptoms
• major cause of mortality is sudden death. Predictors include age < 30 years, VT on Holter, marked ventricular hypertrophy, syncope and family history of sudden death
• no correlation between risk of sudden death and severity of symptoms or presence or severity of outflow gradient. Haemodynamic factors appear to play a role. Likely that most deaths are due to ventricular arrhythmias

Peripartum cardiomyopathy

Primary cardiac failure of uncertain cause during last month of pregnancy or first 6 months postpartum.

- rare
- higher incidence in older, multiparous women
- associated with pre-eclampsia, obesity, breast-feeding, multiple gestations

- presents with progressive signs and symptoms of CCF

- cardiomegaly, pulmonary venous congestion and pulmonary oedema on CXR
- Echo: atrial and ventricular enlargement and decreased ventricular function
- endomyocardial biopsy: degenerative changes including hypertrophy, fibrosis, lipid deposition

- conventional management of cardiac failure +/- shock
- ensure uterine displacement
- early delivery removes some cardiovascular stress from mother
- anti-coagulate after delivery: high incidence of embolic events

© Charles Gomersall July 1999

©Charles Gomersall, September, 2008 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
Copyright policy    Contributors