Case 10: Sade A.

Cardiomyopathy (CM): Description

Heart muscle disorders

CM: Types

1. Dilated (DCM)

2. Hypertrophic (HCM)

3. Restrictive (RCM)

DCM: Description

Enlarged LV

Diastolic Function: Normal

Systolic Function: Decreased

HCM: Description

Thick ventricular wall

• Concentric hypertrophy not from pressure overload

Diastolic Function: Decreased

• Increased LV filling pressure

Systolic Function: Normal

RCM: Description

Stiff myocardium from fibrosis and infiltrative processes

Diastolic Function: Decreased

Systolic Function: Normal

DCM: Etiology

Primary: Idiopathic

Genetic abnormalities

Inflammatory myocarditis

Cocaine

DCM: Pathogenesis

Genetic:

1. Gene mutations cause abnormal proteins = Insufficient function

2. Compensatory myocardial stretch to increase CO = LV dilation + Decreased contractility = Alter force generation and transmission = Decrease SV and CO

• Cell death

• Start in LV, progress to RV

Acquired: Drugs suppress cardiac contractility and activate neurohormonal systems

DCM: Treatment

Treat underlying cause

• HF:

  • Diuretics

  • Beta-blockers

  • Ca2+ channel blockers (CCBs)

  • Angiotensin-Converting Enzyme Inhibitors (ACEIs)

  • Angiotensin Receptor Blockers (ARBs)

  • Limit Na+ intake

• Reduce alcohol

Manage complications

• HF

• Thromboembolic events: Anticoagulants

• Severe:

  • AICD

  • Heart transplant

HCM: Etiology

Dominant autosomal mutations change myofilament protein production

HCM: Pathogenesis

1. Ischemia = Scarring = Asymmetric interventricular septum hypertrophy

2. Hypertrophy = Decrease compliance + diastolic relaxation

• No Obstruction: Increase outflow pressure (no block)

• Obstruction: Systolic anterior motion (SAM) or mitral valve leaflets (dynamic)

  • From high flow producing Venturi forces (low pressure) = Pull in leaflets

  • Block outflow tract

HCM: Treatment

Lifestyle changes: Avoid activities causing vasodilation (high temp, exercise)

AICD: Prevent sudden cardiac death

Pharmacological: Reduce heart contraction and HR

• Beta-blockers (first-line)

• Nondihydropyridine CCBs (second-line)

• AVOID DIURETICS

Septal reduction:

• Surgery

• Ablation

RCM: Etiology

Myocyte infiltration (amyloidosis depositing amyloid fibrils)

Abnormal storage in myocytes

Fibrosis

Idiopathic

RCM: Pathogenesis

1. Infiltration/fibrosis = Decrease LV compliance (elasticity) = Increase diastolic pressure + Decrease diastolic filling

2. Cause:

• Increased systemic and pulmonary venous pressure (venous congestion)

• Decreased SV and CO

RCM: Treatment

Difficult to treat (limited options, high mortality)

Treat underlying cause (HF)

Severe: Heart transplant

• Cannot undergo = Palliative care

Compare and Contrast CM: Ventricular Chamber Size

DCM: Increased

HCM: Normal/decreased

RCM: Normal/decreased

Compare and Contrast CM: Ventricular Wall Changes

DCM: No hypertrophy

HCM: Hypertrophic (asymmetric)

RCM: Fibrotic and infiltrated myocardium

Compare and Contrast CM: Etiology

DCM: Genetic, inflammation (myocarditis)

HCM: Genetic

RCM: Genetic (amyloidosis)

Compare and Contrast CM: Symptoms

DCM:

• Dyspnea

• Fatigue

• Weakness

• Orthopnea

• PND

HCM:

• Dyspnea

• Angina

• Syncope

RCM:

• Dyspnea

• Fatigue

Compare and Contrast CM: Physical Exam

DCM:

• S3

• Pulmonary crackles

• RV failure: Peripheral edema, hepatomegaly, high JVP

• Systolic murmur (AV valve regurg)

HCM:

• S4

• Obstruction: Systolic murmur (mitral regurg)

RCM:

• RV failure

Compare and Contrast CM: Systolic Contraction

DCM: Decreased

HCM: Normal/increased

RCM: Normal

Compare and Contrast CM: Diastolic Relaxation

DCM: Normal

HCM: Decreased (assess with Doppler)

RCM: Decreased (assess with Doppler)

Compare and Contrast CM: Atrial Size

DCM: Increased (decompensated)

HCM: Increased

RCM: Increased

Compare and Contrast CM: Cardiac Size on CXR

DCM: Enlarged

HCM: Normal/enlarged

RCM: Normal

Compare and Contrast CM: Echo

DCM:

• Dilated

• Poor LV contraction

HCM:

• LV hypertrophy (septal)

• Systolic anterior mitral valve movement + regurg

RCM:

• Normal systolic contraction

• Increased echogenicity (infiltration)

DCM: PV Loop Changes

Increased ESV: Enlarged LV = Increased LV volume

Increased EDV (Preload): Decreased contractility = Decreased SV and CO

Increased Afterload: RAS activation = Increase pressure against LV

Less Steep ESPVR: Decreased contractilty

• High volume changes = Low pressure changes

Increased Ventricular Filling Pressure: Decreased compliance + Increased LV size

HCM: PV Loop Changes

Normal/Decreased ESV: No systolic dysfunction

Decreased EDV (Preload): LV hypertrophy = Decreased compliance + volume = Decreased SV and CO

Increased Afterload: In LV outflow obstruction

Steep EDPVR: Increased LV stiffness from hypertrophy = Decreased compliance + Diastolic function

• Low volume changes = High pressure changes

RCM: PV Loop Changes

Normal/Increased ESV: No systolic function changes

Normal/Decreased EDV (Preload): Decreased LV compliance (no dilation) = Decreased filling

Steep EDPVR: Increased LV stiffness = Decreased compliance

• Low volume changes = High pressure changes

Diastolic HF: Description

In Alessandra W.

HF from low ventricular compliance (HFpEF)

• Increased filling pressure

• Abnormal relaxation

• Increased ventricle stiffness

Diastolic HF: Epidemiology/Etiology

Hypertension (most common)

CAD

HCM

Diastolic HF: Pathogenesis

1. Decreased LV compliance

• LV hypertrophy + stiffening = Poor LV relaxation

2. LV diastolic dysfunction = Low CO + Normal EF (no increase with stress)

• Increased diastolic pressure = Decreased LV filling

Diastolic HF: Investigations

Echo (TTE) + doppler

ECG

Blood test

Natriuretic peptide biomarkers

Diastolic HF: Echo + Doppler

Diastolic dysfunction

LV hypertrophy

Diastolic HF: ECG

LV hypertrophy

• Wide QRS

• High R peak

• Deep S peak

• ST elevation

Diastolic HF: Blood Test

CBC

Electrolytes

TSH

Diastolic HF: Natriuretic Peptide Biomarkers

Increased

• B-type natriuretic peptide (BNP)

• N-terminal prohormone of B-type natriuretic peptide (NT-proBNP)

Diastolic HF: Clinical Presentation

Pulmonary edema

• Dyspnea on exertion

• Tachypnea

Hypertension

Irregular pulse (atrial fib)

S3 and S4

Diastolic HF: Treatment/Management

Prevent volume overload and maintain filling pressures

• Healthy diet

• Increased exercise

• RAS inhibitors (ARBS, angiotensin receptor-reprilysin inhibitors (ARNIs))

• Diuretics (lower dose)

• SGLT2 inhibitors

Atrial Fib leading to HF

Loss of coordinated atrial contraction

Structural remodelling

Increased LA pressure and volume

Loss of Coordinated Atrial Contraction

Decrease ventricular filling = Decrease CO = HF

Chronic: LV systolic dysfunction + Dilation = Worsen HF

Structural Remodelling

Atrial and ventricular fibrosis = Decreased ventricular compliance + Contractility = HF

Increased LA Pressure and Volume

Increased pressure + volume = Increased atrium size + Pulmonary venous pressure = Worsen HF

Troponin (Tn)

Regulatory protein in muscle cells controlling interaction between myosin and actin

Released from normal cell turnover

Serum Tn Elevation

Indicate cardiomyocyte injury

Serum Tn Elevation Mechanism

1. Cardiomyocyte injury = Disrupt sarcoplasma membrane = Tn leak from intracellular compartment into circulation

2. Prolonged myofibril degradation = Prolonged Tn release

B-Type/Brain Natriuretic Peptide (BNP)

Biomarker produced by ventricular myocardium under hemodynamic stress

Cause vasodilation (decrease BP) and Na+/water excretion (decrease volume)

Serum BNP Elevation

Indicate volume/pressure overload (HF)

ProBNP (prohormone) → BNP + N-terminal proBNP (NT-proBNP)

• Normal BNP: < 100 pg/mL

• Normal NT-proBNP: < 300 pg/mL

Correlated with severity

Serum BNP Elevation Mechanism

1. Myocardial wall tension/stretch = Activate mechano-ion channels = Increase Ca2+ influx

2. Activate BNP gene transcription + translation = Secrete proBNP

3. ProBNP cleave into BNP and NT-proBNP → Circulation

Hypertrophy Types

Concentric

Eccentric

Concentric Hypertrophy

Thickening myocytes in parallel = Increased wall thickness without proportional chamber dilation (decrease wall stress)

From chronic pressure overload

• Ex: Hypertension, valve stenosis

Eccentric Hypertrophy

Elongating myocytes in series = Increased wall thickness with proportional chamber dilation

From chronic volume overload

• Ex: Regurg