Lesson 2 DILATED CARDIOMYOPATHY ETIOLOGY AND PATHOPHYSIOLOGY

WHAT IS DILATED CARDIOMYOPATHY? what is it Characterized by and cannot be explained by what, name two examples of abnormal loading conditions?

Dilated cardiomyopathy: “Characterized by LV dilation and LV systolic dysfunction that cannot be explained by abnormal loading conditions.” •

Hypertension •

Valvular heart disease

The definition is basically saying:

DCM is when the LV becomes enlarged and weak WITHOUT another condition causing extra pressure or volume stress on the heart.

So your teacher is saying:

• If the LV is dilated because of long-term hypertension

• Or because of valvular disease

…then technically the dilation may not be considered “primary” dilated cardiomyopathy, because there is another reason the heart got overloaded.

Simple breakdown:

• Hypertension = pressure overload
  The LV has to pump against high blood pressure for years → eventually weakens and dilates.

• Valvular heart disease = pressure or volume overload
  Example:

  • Aortic stenosis → pressure overload

  • Mitral regurgitation → volume overload

These conditions “load” the ventricle abnormally.

So when doctors diagnose true DCM, they try to make sure the LV dysfunction is not simply explained by:

• chronic hypertension

• severe valve disease

That’s why those were listed under the definition slide.

A super simple way to think about it:

Condition	Why LV dilates
Primary DCM	Heart muscle disease itself
Hypertension	Heart working against high pressure
Valve disease	Heart overloaded with pressure or blood volume

So the phrase:

“cannot be explained by abnormal loading conditions”

basically means:

“the weak, enlarged LV is not just from high BP or valve problems.”

That distinction is important clinically because DCM is a primary myocardial disease, not just a response to increased workload.

what classification is DCM in?

Primary cardiomyopathies, mixed ( can be both genetic and acquired)

what is the Idiopathic ETIOLOGY, and what is the % of cases?

Idiopathic – 50% of cases •

A disease of no known cause •

Not relating to any other disease process

what is the familial etiology and what % of the cases?

1. due too

2. what is more common

3. can be what or what

Familial – 25% of cases

• Hereditary •

Typically, autosomal dominant is more common •

can be recessive or X-linked

the etiology of the known causes of what % of the cases?

Known causes- 25% of cases

name 5 KNOWN CAUSES OF DCM

Infectious (viral, bacterial, fungal)

Immunologic (after vacation)

Metabolic/nutritional (transplant like the liver or kidney and can cause DCM b/c of regection)

Neuromuscular disorders (Muscular dystrophy)

Toxic (alcohol, cocaine use, chemothearpy agents)

EPIDEMIOLOGY:

The estimate for age-adjusted prevalence of DCM in the U.S. was _____cases over _______people

The estimate for age-adjusted prevalence of DCM in the U.S. was 36 cases over 100,000 people

It means that, after adjusting for differences in age between populations, about 36 out of every 100,000 people in the United States have dilated cardiomyopathy (DCM)

EPIDEMIOLOGY:

Updated estimate suggested a higher prevalence showing DCM ____ in ____individuals

Updated estimate suggested a higher prevalence showing DCM 1 in 250 individuals

EPIDEMIOLOGY:

If there is not clinically identifiable cause

what % of patients have a _____reason?

Over how many genes have been linked to DCM

25%-35% of patients have a genetic reason •

Over 50 genes have been linked to DCM

Sometimes doctors cannot find a clear reason WHY someone has dilated cardiomyopathy (DCM). But even when there is no obvious cause, genetics may still be responsible.

more than 50 different genes

that can lead to dilated cardiomyopathy.

Epidemiology means the study of incidence, distribution, and possible control of diseases

how common is DILATED CARDIOMYOPATHY?

The most common cardiomyopathy

Dilated cardiomyopathy is the what number most common cause of heart failure?

3rd most common cause of heart failure

Dilated cardiomyopathy is the most frequent cause of what?

Most frequent cause of heart transplant

H&P, name 6 (History and Physical)

Recent pregnancy

• Infection exposure •

Heart failure history? Symptoms? (SOB, swelling etc.) •

Palpitations •

Cyanosis •

Low blood pressure

CLINICAL PRESENTATION • Signs and symptoms name 6

Fatigue •

Decreased exercise tolerance •

Dyspnea (SOB)

• Orthopnea • (SOB while lying flat)

Paroxysmal nocturnal dyspnea • (SOB while sleeping)

Chest discomfort

PHYSICAL EXAMINATION- EVIDENCE OF LEFT HEART FAILURE name 4

Normal to low BP •

Pulsus alternans (severe left ventricular failure) (strong heart beat and next is small, heart rhytm doesn’t change, changes the strength if the heart beat tells us LV HF, can see this on EKG)

Tachycardia •

Lung crackles (pulmonary edema)

PHYSICAL EXAMINATION- EVIDENCE OF RIGHT HEART FAILURE name 4

Hepatomegaly (enlarged liver)

Elevated JVP • (Elevated jugular venous pressure (JVP) indicates increased pressure in the right atrium and venous system,)

Peripheral edema •’ (swelling in the legs,)

Ascites (abnormal buildup of fluid in the abdominal cavity)

EKG name 6 and describe the p - wave

Sinus tachycardia •

Nonspecific ST-T wave abnormalities •

Atrial arrythmias or atrial fibrillation •

Ventricular arrythmias

• LBBB******

• Left atrial enlargement*****

the p-wave is long / the duration or width of the p wave is increased and the amplitude of the p wave is not increased

CARDIAC AUSCULTATION

1. paradoxical splitting of the second heart sound with _____

2. Accentuated pulmonary component of the 2nd heart sound of what present?

3. s_ and s_ with ventricular ______

4. systolic murmurs of what?

Paradoxical splitting of the second heart sound with LBBB

• Accentuated pulmonary component of the 2nd heart sound of pulmonary HTN is present •

S3 with ventricular decompensation •

S4 •

Systolic murmurs of mitral and tricuspid regurgitation

Paradoxical = occurring in the opposite or unexpected way from normal.

LBBB stands for Left Bundle Branch Block.

It means the electrical signal is delayed or blocked in the left bundle branch, so the left ventricle gets activated later than normal.

Normally:

• Electrical impulse travels:

  • AV node → Bundle of His → Right & Left bundle branches

• Both ventricles contract almost together.

With LBBB:

• The right ventricle activates first

• The left ventricle activates late

• This causes the ventricles to beat out of sync.

Ventricular decompensation means the ventricle can no longer compensate well enough to maintain normal heart function.

In other words:

The heart muscle has become too weak or overstretched, and the compensatory mechanisms are starting to fail.

Normally, the second heart sound (S2) is:

• A2 = aortic valve closes first

• P2 = pulmonic valve closes second

During inspiration, they split a little:

“dub … dub”

With LBBB (Left Bundle Branch Block), the electrical signal gets delayed to the left ventricle.

That means:

• the LV contracts later

• the aortic valve closes later than normal

So now:

• P2 happens first

• A2 happens second

This reversed order is called paradoxical splitting.

explain the purposse for Genetic Testing/Labs

(guides what or identifies what?)

Guides treatment or identifies risk

Chest X ray, what do you see

Cardiomegaly, pulmonary congestion

Cardiac Magnetic Resonance Imaging (MRI), used to assess what?

May be used to assess myocardial injury or inflammation

Cardiac Catheterization, evaluate for the presence of what? and what may be considered

Evaluate for the presence of CAD •

Endomyocardial biopsy may be considered

Exercise testing, may help to determine the cause of what?

May help determine the cause of exercise limitation

SYSTOLIC FUNCTION IN DCM

what are the determinants of ventricular function?

SYSTOLIC DYSFUNCTION, decreased in what 3 things, b/c of the decrease in ____ and ____ what does it cause?

what does it increases (name 4) and cause?

what happens to the LVEDP, LAP, pulmonary capillary pressure- leads to what?

Decreased myocardial contractility

Decreases cardiac output and SV

Because of a decrease in CO and SV…

Causes hypoperfusion to the organs

Increases in ESV, EDV, increased LVEDP/LAP

Pulmonary congestion

Hypoperfusion to the organs is a critical medical condition where blood flow is reduced or restricted, leading to insufficient delivery of oxygen, glucose, and nutrients to tissues.

what are the steps in LV dysfunction

what happens to the volume, pressure, myocardium, contractility, CO - what does it lead to, ESV, EDV- leads to what ? and what is the EF

what 3 things VARIABLES DECREASED IN DCM?

Ejection fraction

Stroke volume

Cardiac output

(variables” just means the measurements/values that change in DCM.

So when the slide says “Variables decreased in DCM,” it means these important heart function numbers go down in dilated cardiomyopathy:

1. Ejection fraction decreases
The LV is weak, so it pumps out a smaller percentage of blood.

2. Stroke volume decreases
Each heartbeat pumps out less blood than normal.

3. Cardiac output decreases
Because stroke volume is lower, the total blood pumped to the body per minute can decrease.

Your slide lists these three as decreased in DCM: ejection fraction, stroke volume, and cardiac output.

Simple way:

Variable = measurable thing.
In DCM, the measurable things that decrease are EF, SV, and CO because the LV is dilated and weak.

COMPENSATORY MECHANISMS, how does the heart compenstate to maintain CO? name 3

Ventricular remodeling •

LV enlargement •

Frank starling relationship

COMPENSATORY MECHANISM: VENTRICULAR REMODELING:

when you hear ventricular remodeling what are the 4 things you should be thinking of and name two things that increase in DCM for a compensatory mechanism? (think of walls too)

Size, shape, structure, function

• LV mass

• LV enlargement

(Eccentric LVH, normal to thin walls - leads to cardiomegaly)

The more blood in, will =

^ causes what ?

producung what compensating for what function?

The more blood in, will = more blood out

LV ENLARGEMENT

Producing a higher stroke volume compensating for decreased systolic function

COMPENSATORY MECHANISMS: FRANK STARLING LAW

increase in what leads to stronger ____ and greater ____

increase in LVEDP leads to stronger contraction and greater SV

(when systolic function or contractility decreases in DCM the volume and the LVEDP will increase to help maintain that SV)

-point A normal, normal pressures, normal SV

• point B shows a decrease in EF, if pressures and volumes arent increase the SV is very reduce and thats what point B is showing

• point C shows a pt with cardiac remodeling done by increaing the pressures and volumes, the SV will increase for a little bit, mechanism works but eventually fails

WHY DIASTOLIC DYSFUNCTION OCCURS IN DCM, list two

LV dilation increases wall stress

Volume overload stretches the LV beyond optimal

LV dilation increases wall stress

the ventricle becomes what size and what shape?

what reduces diastolic compliance?

the LV fills at what pressures? (high or low)

The ventricle becomes large and spherical •

High wall stress reduces diastolic compliance •

The LV fills at higher pressures

Volume overload stretches the LV beyond optimal

what is going on with the preload?

what compensation becomes ineffective?

what does it result in?

Chronic preload elevation •

Frank-starling compensation becomes ineffective •

Results in LVEDP

Results in LVEDP”

LVEDP =
Left Ventricular End-Diastolic Pressure

That means:

pressure inside the LV at the END of filling.

Because:

• too much blood stays in the LV

• the LV is dilated and stiff

• blood backs up

the filling pressure rises.

So:

LVEDP increases.

---

Simple Flow of What Happens

DCM → weak squeeze → blood stays in LV → preload increases → LV stretches too much → Frank-Starling stops helping → LV pressure rises (LVEDP ↑)

2025 ASE DIASTOLOGY ASSESSMENT IN DCM name 6

Mitral E/A ratio

Mitral TDI- relaxation velocity • - thats what it determines (DCM usally has a reduce septal and lateral e ‘ )

E/e’ ratio- estimates filling pressure • ( elavted filling pressures in DCM)

LA volume index (LAVi)- chronic pressure burden (huge LA)

• LA strain

TR (most likely will see in DCM) (b/c of the annulus being streatched)

in early DCM you may see imparied relaxtion, LV becomes more stiff and the LA pressure rise there might be psedu - normal or retricted filling pattern correlates with advanced HF

LA size is important, progonsis valve b/c LA size contribtes to the SV and dialation can change the SV, pt with LAE are prone to hospitalization and mortaility

what are primary cardiomyopathis?

inflammatory (myocarditis)

peripartum

what are secondary cardiomyopathis?

1. toxicity, drugs, heavy metals, chemical agents

2. consequence of cancer therapy

(Pathological myocardial involment as part to many systemic or multiple organ disorders that can lead to CV issues)

INFLAMMATORY (MYOCARDITIS) CARDIOMYOPATHY

________Cardiomyopathy presenting as DCM

AHA classification: is what?

Viral myocarditis can trigger what reaction that causes _______ damage to the ______?

___responsible overlap with that of DCM etiology

may be what?

can it be reversible ?if so how

Primary Cardiomyopathy presenting as DCM •

AHA classification: Acquired •

Viral myocarditis can trigger an autoimmune reaction that causes immunologic damage to the myocardium •

(commonly known as autoimmune myocarditis or inflammatory cardiomyopathy, occurs when the body's immune system mistakenly attacks its own heart muscle.)

Agents responsible overlap with that of DCM etiology •

(The things that CAUSE myocarditis are often the SAME things that can CAUSE DCM.)^^^^

May be acute or chronic •

May be reversible (medications, lifestyle changes etc.)

Acquired” means the condition is considered non-genetic (non-hereditary) and develops later because of something that happens to the person.

In DCM, an immunologic cause means:

the body’s immune system damages the heart muscle.

Sometimes this happens after:

• a viral infection

• inflammation

• an autoimmune reaction

Example:
A virus infects the heart → immune system attacks the virus → sometimes it accidentally attacks the myocardium too → heart muscle becomes weak and dilated.

Your slide mentions:

“Viral myocarditis can trigger an autoimmune reaction that causes immunologic damage to the myocardium.”

Simple flashcard:
Immunologic
= caused by or related to the immune system damaging tissue.

• Agents responsible = the causes (viruses, toxins, infections, etc.)

• overlap = are shared/similar

• DCM etiology = causes of dilated cardiomyopathy

So your teacher is saying:

Many causes of myocarditis are also causes of DCM.

Example:

• Viral infection → myocarditis → heart muscle damage → can eventually lead to DCM

• Alcohol/toxins → direct heart damage → DCM

• Autoimmune inflammation → myocarditis and DCM

Person gets sick with a virus.

Like:

• flu

• COVID

• bad infection

---

Step 2:

The immune system attacks the infection.

Normally this helps.

BUT sometimes:

• the immune system also attacks the HEART muscle accidentally.

---

Step 3:

The heart muscle becomes inflamed.

Inflammation damages the myocardium.

Now the heart may:

• weaken

• enlarge

• pump poorly

This can look like:

dilated cardiomyopathy (DCM)

---

Why Does It Become DCM?

When inflammation damages the muscle:

• contractility decreases

• EF drops

• LV enlarges

So the patient develops:

• systolic dysfunction

• dilated ventricle

which is why myocarditis can PRESENT as DCM.

ETIOLOGY (CAUSE) of INFLAMMATORY (MYOCARDITIS) CARDIOMYOPATHY, name 3 which one is the most common?

CASE STUDY 35 yo F

Diagnosed with covid- 19 2/2021

Arrived at the hospital with respiratory failure

Echo performed 3/2021

whats the Diagnosis-?

Diagnosis- myocarditis and multisystem inflammatory syndrome secondary to covid-19

PERI/POSTPARTUM CARDIOMYOPATHY

Primary or secondary? Cardiomyopathy presenting as DCM •

AHA classification: what is it

explain what it is and the cause

• Peripartum = around the time of delivery

• Postpartum = after delivery

• Primary Cardiomyopathy presenting as DCM

AHA classification: acquired

Dilated form of cardiomyopathy

• Idiopathic

PERI/POSTPARTUM CARDIOMYOPATHY

when during pregnancy?

may occur in what women age’s?

most common after what age ?

what may be this be from?

is this reversible ?

Late in the 3rd trimester OR in the First 5 months after pregnancy •

May occur in childbearing women of any age •

Most common after age 30 •

May be from the stress of pregnancy (idiopathic cause) •

Reversible DCM

PERI/POSTPARTUM CARDIOMYOPATHY

what are the Risk factors? name 8

Obesity •

h/o other CV disorders • '

Certain medications •

Smoking •

Alcoholism •

Multiple pregnancies •

African American descent •

Poor nourishment

ALCOHOLIC CARDIOMYOPATHY

AHA classification: what is it?

due to what condition that involes what?

its from what? can this be reversible ?

consuming what per day and how many days risks developing what ?

AHA classification: Secondary •

Due to a systemic condition that involves the myocardium

• Toxicity •

May be reversible •

Consuming 6 drinks of alcohol per day > 5 days, risks developing asymptomatic DCM

Simple Way to Think About It Primary cardiomyopathy:

Problem starts mainly in the heart itself.

Secondary cardiomyopathy:

Something ELSE in the body damages the heart.

The heart problem is happening because of another disease or condition affecting the whole body.

Systemic condition = a disease/problem affecting the body overall.
Myocardium = heart muscle.

So:

“Due to a systemic condition that involves the myocardium” means:
A body-wide condition is affecting/damaging the heart muscle, causing cardiomyopathy.

CASE STUDY

09/2021- 36 yo M arrived to ED with LE edema

Hx drinking 30 pk beers/night from age 16 Viral panel negative

Follow up echo 1.5 years later after drinking cessation

ALCOHOLIC CARDIOMYOPATHY

CHEMOTHERAPY CARDIOTOXIC AGENTS, some chemotherapeutic drugs may be what?

may occur when?

follow up every how many if what agent is utilized ?

what is very important to use/ check for this pt

Some chemotherapeutic drugs may be cardiotoxic

May occur during or even years after treatment

Follow up every 3 months if cardiotoxic agent is utilized (STRAIN)

(LV strain - predicts LV function and EF and important to check)

In DCM, cardiotoxic injury can weaken the myocardium so the ventricle dilates and systolic function decreases.

Simple definition:

Cardiotoxic = harmful to the heart muscle or heart function.