Dilated Cardiomyopathy Practicum

What is dilated cardiomyopathy?

Dilated cardiomyopathy, or DCM, is characterized by left ventricular dilation and LV systolic dysfunction that cannot be explained by abnormal loading conditions, such as hypertension or significant valvular heart disease.

What is the main functional problem in DCM?

The enlarged ventricle has decreased myocardial contractility, causing reduced systolic function, stroke volume, cardiac output, and ejection fraction.

Research and Preparation Before the Examination

What information should be reviewed before beginning the echocardiogram?

• The reason for the examination

• Previous echocardiograms

• Previous EF, chamber sizes, and valve findings

• ECG findings

• Chest X-ray results

• Cardiac MRI or catheterization results

• Laboratory or genetic-testing results

• History of coronary artery disease or previous myocardial infarction

• History of hypertension or valvular disease

• Previous pacemaker, ICD, or CRT placement

What clinical-history questions should be asked?

Heart-failure symptoms

Ask the patient:

• Are you experiencing shortness of breath?

• Does the shortness of breath worsen with activity?

• Do you have difficulty breathing while lying flat?

• Do you sleep with extra pillows or in a recliner?

• Do you wake up at night short of breath?

• Have you noticed swelling in your legs or abdomen?

• Have you experienced fatigue?

• Has your exercise tolerance decreased?

• Are you experiencing chest discomfort?

• Have you had palpitations?

• Have you experienced dizziness, low blood pressure, fainting, or cyanosis?

Questions that help determine the cause

Ask about:

• Recent viral illness or infection exposure

• Recent COVID-19 or possible myocarditis

• Current or recent pregnancy

• Whether symptoms began during the third trimester or within five months after delivery

• Family history of cardiomyopathy, heart failure, transplant, or sudden cardiac death

• Alcohol consumption and length of alcohol use

• Chemotherapy or other cardiotoxic medications

• Smoking

• Poor nutrition

• Metabolic or neuromuscular disorders

• Previous myocardial infarction or coronary artery disease

• History of arrhythmias

• History of LBBB

• History of chronic pacing

• History of hypertension

• History of significant valve disease

What physical findings may be present with left-sided heart failure?

• Normal-to-low blood pressure

• Tachycardia

• Pulsus alternans in severe LV failure

• Lung crackles caused by pulmonary edema

What physical findings may be present with right-sided heart failure?

• Elevated jugular venous pressure

• Hepatomegaly

• Peripheral edema

• Ascites

What additional diagnostic tests may support the examination?

ECG may demonstrate:

• Sinus tachycardia

• Nonspecific ST-T abnormalities

• Atrial arrhythmias or atrial fibrillation

• Ventricular arrhythmias

• LBBB

• Left atrial enlargement

Other testing may include:

• Genetic testing and laboratory testing

• Chest X-ray for cardiomegaly and pulmonary congestion

• Cardiac MRI for myocardial injury or inflammation

• Cardiac catheterization to evaluate for coronary artery disease

• Possible endomyocardial biopsy

• Exercise testing to determine the cause of exercise limitation

Appropriate Echocardiographic Protocol

A patient with suspected DCM should receive a complete transthoracic echocardiogram, not only limited images of the LV.

What should be evaluated in the parasternal long-axis view?

• LV internal dimensions

• LV wall thickness

• LV mass

• Global LV contractility

• Mitral valve motion and coaptation

• Functional mitral regurgitation

• EPSS

• Aortic root motion

• Timing of aortic valve closure

• Pericardial effusion

• Possible intracardiac device leads

What should be evaluated in parasternal short-axis views?

Evaluate:

• LV shape and spherical remodeling

• Global and regional wall motion

• RV size

• Septal motion

• Mechanical dyssynchrony

• Mitral valve anatomy

• Papillary-muscle position

• Possible thrombus when visible

Obtain short-axis views at the:

• Aortic valve level

• Mitral valve level

• Papillary-muscle level

• Apical level

What should be evaluated in the apical four-chamber view?

Evaluate:

• LV and RV size

• LA and RA size

• Global LV systolic function

• Regional wall motion

• Mitral and tricuspid regurgitation

• Mitral inflow

• Mitral annular tissue Doppler

• TR velocity

• RV function

• Possible apical thrombus

• Mechanical dyssynchrony

Use an RV-focused apical four-chamber view for:

• RV basal and mid diameters

• RV length

• FAC

• TAPSE

• S′ velocity

• RV strain

What should be evaluated in the apical two-chamber view?

Evaluate:

• Anterior and inferior LV walls

• LV length

• Regional wall motion

• LV volumes

• Biplane ejection fraction

• Possible apical thrombus

What should be evaluated in the apical three- or five-chamber views?

• LVOT flow

• Aortic valve opening

• Mitral regurgitation

• LV mechanical timing

• Stroke volume

• Possible device-related findings

What should be evaluated in the subcostal view?

• IVC diameter

• Inspiratory collapse

• Estimated right atrial pressure

• Right-sided chamber enlargement

• Pericardial effusion

• Device leads when present

What measurements and Doppler recordings are particularly important?

Obtain:

• LV dimensions and wall thickness

• LV mass

• LV end-diastolic and end-systolic volumes

• Biplane EF

• Global longitudinal strain

• Fractional shortening

• Sphericity index

• LA volume index

• Pulmonary-vein Doppler

• Mitral inflow PW Doppler

• Mitral annular TDI

• E/e′

• TR CW Doppler

• IVC size and collapse

• RVSP

• RV dimensions and function

• MR and TR quantification when present

When should ultrasound-enhancing contrast be used?

Use Definity or another ultrasound-enhancing agent when:

• Endocardial definition is poor

• The LV apex is not clearly visualized

• An apical thrombus is suspected

• The EF is less than 30%

Sonographic Findings Using Appropriate Terminology What are the primary 2D findings of DCM?

• Dilated left ventricle

• Increased LV mass

• Spherical LV remodeling

• Severely or moderately reduced global LV systolic function

• Global LV hypokinesis

• Reduced EF

• Abnormal GLS

• Reduced fractional shortening

A strong description would be:

“The left ventricle is severely dilated with spherical remodeling and severe global hypokinesis, resulting in severely reduced LV systolic function.”

What is the expected wall-motion pattern in primary nonischemic DCM?

The typical pattern is:

“Global hypokinesis with uniformly reduced motion of all LV myocardial segments.”

Regional wall-motion abnormalities suggest a possible secondary cause rather than uncomplicated nonischemic DCM.

What secondary left-sided findings may be present?

• Mural or apical LV thrombus

• Spontaneous echo contrast, or “smoke”

• Ventricular dyssynchrony

• Abnormal septal motion from conduction delay

• LA enlargement

• Dilated mitral annulus

• Incomplete mitral-leaflet coaptation

• Mitral-leaflet tethering or tenting

• Functional mitral regurgitation

What right-sided findings may be present?

• RA enlargement

• RV enlargement

• Reduced RV systolic function

• Functional tricuspid regurgitation

• Pulmonary hypertension

• Dilated IVC

• Reduced inspiratory IVC collapse

What diastolic findings are expected?

DCM commonly demonstrates grade II or greater diastolic dysfunction.

Possible findings include:

• Abnormal mitral E/A ratio

• Reduced mitral annular e′ velocity

• Elevated E/e′

• Increased LA volume index

• Abnormal pulmonary-vein flow

• Increased LV filling pressure

• Increased LVEDP

What does spontaneous echo contrast indicate?

Spontaneous echo contrast represents temporary red-blood-cell aggregation caused by a low-flow state. It indicates blood stasis and raises concern for LV thrombus formation.

What M-mode findings may be present?

• EPSS greater than 6 mm

• Mitral-valve B-bump

• Decreased aortic-root motion

• Early aortic-valve closure

Important DCM Measurements

Ejection fraction

Global longitudinal strain

Fractional shortening

Sphericity index; A perfect sphere equals 1.

• A value below 1.5 is associated with poor prognosis.

Left atrial volume index

RVSP

• Normal: 34 mmHg or less

• Mild pulmonary hypertension: 35–49 mmHg

• Moderate: 50–69 mmHg

• Severe: 70 mmHg or greater

Common RV-function measurements

• FAC: normal greater than 35%

• TAPSE: normal greater than 1.7 cm

• TDI S′: normal greater than 9.5 cm/s

• RV strain: slide uses an absolute normal value greater than 20%

Hemodynamics and How They Aid the Diagnosis

What begins the hemodynamic problem in DCM?

The primary problem is decreased myocardial contractility.

Decreased contractility causes:

↓SV→↓CO→systemic hypoperfusion

The principal variables decreased in DCM are:

• Ejection fraction

• Stroke volume

• Cardiac output

What happens to ventricular volumes?

Because the LV cannot eject normally:

• End-systolic volume increases.

• Blood remains in the ventricle after systole.

• End-diastolic volume increases during the next filling cycle.

• LV preload and wall stress increase.

• The LV progressively dilates

What happens to filling pressures?

The enlarged and poorly functioning LV develops:

• Increased LVEDP

• Increased left atrial pressure

• Increased pulmonary venous pressure

• Pulmonary congestion

• Pulmonary edema

• Possible secondary pulmonary hypertension

These hemodynamics explain symptoms such as:

• Dyspnea

• Orthopnea

• Paroxysmal nocturnal dyspnea

• Lung crackles

How does Frank-Starling compensation initially help?

LV enlargement allows the myocardial fibers to stretch, temporarily increasing stroke volume through the Frank-Starling mechanism.

However, with continued dilation:

• The fibers become overstretched.

• The compensation becomes ineffective.

• LV wall stress increases.

• The ventricle becomes spherical.

• Systolic and diastolic function worsen.

Why does diastolic dysfunction develop?

LV dilation and high wall stress reduce ventricular compliance. The ventricle must then fill at increasingly high pressures.

This produces:

• Increased LVEDP

• Elevated E/e′

• LA enlargement

• Pulmonary venous congestion

• Grade II or greater diastolic dysfunction

How does functional mitral regurgitation develop?

LV remodeling causes:

• Mitral-annular dilation

• Papillary-muscle displacement

• Leaflet tethering or tenting

• Incomplete leaflet coaptation

This creates secondary or functional MR. The MR adds further volume overload to the LV and LA.

How does right-heart dysfunction develop?

Increased left-sided and pulmonary pressures may lead to:

• Pulmonary hypertension

• Increased RV afterload

• RV enlargement

• Reduced RV systolic function

• RA enlargement

• Tricuspid-annular dilation

• Functional TR

• Increased systemic venous pressure

• Dilated IVC and reduced collapse

These hemodynamics explain peripheral edema, ascites, elevated JVP, and hepatomegaly.

How does dyssynchrony affect cardiac output?

LV dilation and conduction abnormalities, especially LBBB, cause different myocardial segments to contract at different times.

This produces:

• Inefficient LV contraction

• Abnormal septal motion

• Delayed lateral-wall contraction

• Reduced stroke volume

• Worsened LV performance

Why is thrombus formation a concern?

Severe LV dysfunction creates a low-flow state, particularly at the apex.

Low flow leads to:

• Spontaneous echo contrast

• Blood stasis

• Mural or apical thrombus

• Risk of embolization

Image Critique and Technical Improvements

How should an apical image be critiqued before measuring EF?

Check whether:

• The true LV apex is visualized.

• The LV is not foreshortened.

• The endocardial borders are clearly defined.

• The entire LV is included.

• Depth is not excessive.

• Sector width is narrow enough to maintain frame rate.

• The image is obtained during a stable cardiac cycle.

Technical improvement: Reposition the transducer more laterally or inferiorly until the true apex and the longest LV length are visualized.

What should be corrected if the endocardial border is poorly visualized?

• Adjust overall gain.

• Adjust time-gain compensation.

• Reduce unnecessary depth.

• Optimize focus at the LV level.

• Use harmonic imaging.

• Administer contrast when the apex or at least two contiguous LV segments cannot be identified

How should Simpson’s biplane tracing be improved?

• Trace at true end-diastole and end-systole.

• Trace the compacted endocardial border.

• Exclude papillary muscles and trabeculations from the LV cavity.

• Do not trace through the mitral annulus incorrectly.

• Confirm that the apical four- and two-chamber views are not foreshortened.

How should a suspected apical thrombus be evaluated?

• Obtain multiple apical views.

• Use a focused apical view.

• Reduce gain if excessive gain creates false echoes.

• Increase gain carefully if the cavity is too dark.

• Confirm that the mass is visible in more than one plane.

• Use contrast when the apex is poorly defined or EF is below 30%.

How should MR or TR spectral Doppler be improved?

• Align the CW Doppler cursor parallel to the jet.

• Use multiple acoustic windows.

• Record a complete, dense spectral envelope.

• Avoid measuring an incomplete or poorly aligned signal.

• Adjust the velocity scale and baseline appropriately.

• Use color Doppler first to determine the jet direction.

How should RV measurements be improved?

• Use an RV-focused apical four-chamber view.

• Avoid foreshortening the RV.

• Ensure the RV free wall and apex are included.

• Place the M-mode cursor correctly for TAPSE.

• Place the TDI sample at the lateral tricuspid annulus for S′.

• Trace the RV endocardium accurately for FAC.

How should IVC imaging be improved?

• Use a clear subcostal long-axis view.

• Avoid an oblique IVC measurement.

• Observe the IVC during respiration.

• Document both diameter and inspiratory collapse.

• Do not estimate RAP from IVC size alone.

How should GLS acquisition be improved?

• Avoid foreshortened apical views.

• Include the entire myocardium.

• Optimize frame rate.

• Ensure the software correctly tracks every segment.

• Manually correct poor tracking before accepting the result.

Plausible Diagnosis and Differentials

Dilated cardiomyopathy with global LV systolic dysfunction.

The diagnosis is supported by:

• LV dilation

• Spherical remodeling

• Global hypokinesis

• Reduced EF, GLS, and fractional shortening

• Increased LV volumes

• Functional MR

• Possible chamber enlargement

• Elevated filling pressures

• Possible RV dysfunction and pulmonary hypertension

What abnormal loading conditions must be excluded?

Primary DCM should not be diagnosed when the LV dilation and dysfunction are adequately explained by:

• Chronic hypertension

• Significant valvular heart disease

What are the principal differentials?

Ischemic cardiomyopathy or previous MI with remodeling

Consider this when:

• Regional wall-motion abnormalities follow a coronary distribution.

• Some segments are affected more severely than others.

• The patient has CAD or previous MI.

Primary nonischemic DCM more commonly demonstrates uniform global hypokinesis.

Alcoholic cardiomyopathy

Consider this when:

• There is significant long-term alcohol use.

• Other causes are not identified.

• LV function improves after alcohol cessation.

Chemotherapy-induced cardiomyopathy

Consider this when:

• There is current or previous exposure to cardiotoxic chemotherapy.

• LV dysfunction occurs during treatment or years later.

• GLS becomes abnormal before a major decrease in EF.

What medications are used for DCM?

Diuretics

• Increase urine production

• Reduce excess fluid

• Help reduce congestion and edema

ACE inhibitors

• Alter the RAAS system

• Decrease vascular resistance

• Decrease systolic blood pressure

• Reduce LV workload and afterload

Beta blockers

• Block the effects of epinephrine

• Reduce heart rate

• Reduce blood pressure

• Reduce myocardial workload

Anticoagulants

• Help prevent blood-clot formation

• May be important when severe LV dysfunction, low flow, atrial fibrillation, spontaneous echo contrast, or thrombus is present

Antiarrhythmic medications

• Used to treat or control arrhythmias

What implantable devices may be used?

Pacemaker

• Prevents the heart rate from becoming too slow

• Treats bradycardia or heart block

• May pace the atrium, ventricle, or both

ICD

• Detects ventricular tachycardia and ventricular fibrillation

• Provides antitachycardia pacing

• Delivers a shock when necessary

• Helps prevent sudden cardiac death

• Commonly used in patients with a low EF or previous cardiac arrest

Cardiac resynchronization therapy

CRT is a specialized pacemaker used for mechanical dyssynchrony.

It:

• Coordinates ventricular contraction

• Improves contractile efficiency

• Improves LV performance

• May be the final device treatment before an LVAD or transplant

What advanced mechanical treatments may be used?

Mechanical support may include:

• IABP

• VA-ECMO

• TandemHeart

• Impella

• RVAD

• LVAD

• Biventricular support

VADs are used to:

• Restore cardiac output

• Reduce filling pressures

• Improve oxygen delivery

When is heart transplantation considered?

Heart transplantation is reserved for patients with end-stage heart failure who remain symptomatic despite medical and device therapy.

Management What is the first goal of management?

Determine whether the DCM is:

• Idiopathic

• Familial or genetic

• Infectious or inflammatory

• Peripartum

• Alcohol-related

• Chemotherapy-related

• Ischemic

• Pacing- or LBBB-induced

• Related to another known condition

What should be followed on serial echocardiograms?

Monitor:

• LV size and remodeling

• LV mass

• EF

• GLS

• Fractional shortening

• Diastolic function and filling pressures

• LA volume

• MR severity

• RV size and systolic function

• TR severity

• RVSP

• IVC size and collapse

• Spontaneous echo contrast or thrombus

• Mechanical dyssynchrony

• Response to medication or CRT

What additional issues should be monitored?

• Worsening heart-failure symptoms

• Fluid overload

• Low blood pressure

• Atrial or ventricular arrhythmias

• LBBB or widening QRS

• Thrombus formation

• Pulmonary hypertension

• Progressive RV failure

• Need for ICD or CRT

• Need for mechanical circulatory support

• Need for heart transplantation

How is a potentially reversible cause managed?

Management should address the cause when known:

• Alcohol cessation for alcoholic cardiomyopathy

• Monitoring and treatment following myocarditis

• Pregnancy-related follow-up for peripartum cardiomyopathy

• Serial strain and EF assessment with cardiotoxic chemotherapy

• Treatment of ischemic disease when present

• Device evaluation for pacing-induced dysfunction

What is the overall prognosis of DCM?

The prognosis is variable and depends on:

• Cause

• Severity of LV dysfunction

• Presence of RV dysfunction

• Response to treatment

• Arrhythmias

• Dyssynchrony

• Pulmonary hypertension

• Thrombus

• Whether the condition is reversible

Which forms may be reversible?

The slides identify possible reversibility with:

• Myocarditis

• Peripartum cardiomyopathy

• Alcoholic cardiomyopathy after alcohol cessation

• Some toxic or treatment-related forms when the cause is removed

What sonographic finding is associated with poor prognosis?

A sphericity index below 1.5 is associated with poor prognosis.

What electrical finding is associated with worse outcomes?

A wide QRS or LBBB is associated with:

• Worse LV function

• Mechanical dyssynchrony

• Less efficient contraction

• Worse outcomes

What findings make the prognosis more guarded?

• Severely reduced EF

• Progressive LV dilation

• Marked spherical remodeling

• Severe diastolic dysfunction

• Significant functional MR or TR

• Pulmonary hypertension

• RV failure

• Biventricular failure

• Ventricular arrhythmias

• LV thrombus

• Cardiogenic shock

• Need for LVAD or transplant

A good practicum statement is:

The prognosis is guarded because the patient has severe LV dilation and systolic dysfunction with elevated filling pressures and secondary valvular regurgitation. Prognosis depends on the underlying cause, response to medical or device therapy, and the presence of arrhythmias, pulmonary hypertension, or right-heart failure.”

or

The examination demonstrates a severely dilated, spherically remodeled left ventricle with severe global hypokinesis and severely reduced LV systolic function. There is associated elevated LV filling pressure, left atrial enlargement, mitral-annular dilation with functional mitral regurgitation, and evidence of a low-flow state. These findings are most consistent with dilated cardiomyopathy. Ischemic cardiomyopathy, myocarditis, pacing- or LBBB-induced cardiomyopathy, peripartum cardiomyopathy, alcoholic cardiomyopathy, and chemotherapy-related cardiotoxicity should be considered based on the clinical history.