Myocardial diseases - Internal medicine Flashcards
Definition of Dilated cardiomyopathy
DCM is a clinical diagnosis characterized by left ventricular or biventricular dilation and impaired contraction that is not explained by abnormal pathology such as valvular diseases.
Pathophysiology of Dilated cardiomyopathy
- Myocardial fibrosis induced systolic dysfunction leads to decreased ejection of blood and increasing of residual blood volume after each contraction. This increase in the pre-load will lead to compensatory dilatation and thinning of the left ventricle.
- Dilatation of the left ventricle leads to mitral annular dilatation and secondary mitral regurge which will increase the preload and induce more left ventricular dilatation.
- With time, such compensatory mechanism fails to compensate leading to pulmonary congestion and low cardiac output (clinical heart failure). Prolonged pulmonary congestion will induce pulmonary hypertension and right sided HF.
- In some cases, DCM affect both ventricles from the start causing biventricular failure.
Classification and Causes of Dilated cardiomyopathy (A++++++)
A * Ischemic dilated cardiomyopathy, caused by coronary artery disease (CAD)
B * Non-ischemic dilated cardiomyopathy, it is due to:
o 1ry
▪ Genetic predisposition
▪ Non genetic predisposition (potentially reversible)
* Myocarditis
* Pregnancy (Peripartum cardiomyopathy)
* Tachycardia (tachy-cardiomyopathy)
* Stress (stress cardiomyopathy)
▪ Mixed (both genetic and non-genetic predisposition)
o 2ry
a▪ Infectious:
-Viral e.g Hepatitis C, Covid19, Coxsackie B virus.
- Chaga’s disease (a tropical parasitic disease by Trypanosoma cruzi).
B▪ Collagen diseases e.g., Rheumatoid arthritis, systemic lupus erythematosus.
C▪ Endocrinal: Myxedema, DM, Acromegaly
D▪ Toxic e.g., Alcohol, chemotherapy, anabolic steroids.
Presentation of Dilated cardiomyopathy (B)
▪ The patient could be asymptomatic at early stages of DCM and accidentally discovered during pre-operative cardiac evaluation.
▪ The patient could present with gradual onset of isolated left ventricular failure or biventricular failure that will result in:
o Pulmonary congestion
o Low cardiac output
o Systemic congestion
▪ The first presentation of the patient could be acute heart failure and acute pulmonary edema on top of precipitating factors such as (pregnancy, atrial fibrillation, or severe chest infection)
▪ The patient could experience a symptom of complication such as irregular palpitations (due to AF) or hemiplegia (due to thromboembolism)
Management of Dilated cardiomyopathy (A+++++)
A Examination:
1: General signs (details in heart failure)
▪ Signs of pulmonary congestion
-Dyspnea, orthopnea, and paroxysmal nocturnal dyspnea
- Hemoptysis
- Cough
- Recurrent chest infection
▪ Signs of systemic congestion
-edema
-Dyspepsia
-Ascites
-Right hypochondrial pain
▪ Signs of complications (AF / stroke)
2: Local cardiac examination:
▪ Signs of left ventricular or biventricular dilatation
▪ Murmurs of secondary mitral regurge and tricuspid regurge
▪ Signs of pulmonary hypertension
B Investigations: the same for heart failure to detect left ventricular or biventricular dilatation and systolic dysfunction with pulmonary congestion
■ECG
■Chest X ray
■ Echocardiography
(All check for chamber enlargement )
■ Cardiac MRI
■Coronary angiography in patients with suspected ischemic heart diseases
■Laboratory investigations
- Brain natriuretic peptides (BNP)
- Kidney function tests
- Liver functions tests
- Iron indices to check for underlying iron deficiency
- Complete blood count
C Treatment (the same of heart failure):
1 Control of congestion: by diuretics
2 Start of disease modifying treatments: (ACEI/ARBS/ARNI, BB, MRA, and SGLT2i)
3 Lifestyle modification and controlling risk factors and precipitating factors
(same as HF)
4 Management of associated comorbidities (same as HF)
5 Interventional and surgical options (same as HF)
Definition of Restrictive Cardiomyopathy
- RCM a rare disease of the myocardium that is characterized by diastolic dysfunction and restrictive ventricular physiology (impaired filling) with subsequent diastolic heart failure, dilated both atria, and normal left ventricular systolic function.
Pathophysiology of Restrictive cardiomyopathy
- Myocardial fibrosis or infiltration leads to increase in myocardial stiffness and decrease in left ventricular compliance that will lead to impaired diastolic filling with subsequent low cardiac output and elevated left atrial pressure despite normal systolic function
- Increased left atrial pressure leads to
o pulmonary congestion and manifestations of left sided heart failure
o Atrial stretch induced atrial arrhythmias (commonly atrial fibrillation)
o Atrial dilatation induced secondary mitral regurgitation - Prolonged pulmonary congestion leads to development of pulmonary hypertension and right sided heart failure
- Myocardial fibrosis could affect both ventricles from the start resulting in biventricular diastolic heart failure with subsequent bi-atrial dilatation and secondary tricuspid and mitral regurgitation.
Classification and causes of Restrictive cardiomyopathy (B)
- RCM without increased LV wall thickness
o Idiopathic RCM
o Endomyocardial fibrosis
o Radiation heart disease
o Iron overload cardiomyopathy - Infiltration RCM with increased LV wall thickness
o Amyloidosis
o Glycogen storage diseases (Fabry
disease)
Presentation of Restrictive cardiomyopathy (B)
▪ The patient could present with gradual onset of isolated left ventricular failure, biventricular failure, or in some times isolated right sided heart failure that will result in:
o Pulmonary congestion (left sided HF)
o Low cardiac output
o Systemic congestion (right side HF and biventricular failure)
▪ The patient could present with electrical complications such as atrial fibrillation that could precipitate acute heart failure as in the case scenario above
Management of Restrictive cardiomyopathy (B)
A Examination
1 General signs (details in heart failure)
▪ Signs of pulmonary congestion
▪ Signs of systemic congestion
▪ Signs of complications (AF / stroke)
2 Local cardiac examination:
▪ Absence of signs of ventricular dilatation
▪ Murmurs of secondary mitral regurge and tricuspid regurge
▪ Signs of pulmonary hypertension
B Investigations:
1 Laboratory investigations
▪ Brain natriuretic peptides (BNP) could differentiate between cardiac and non-cardiac dyspnea
2 ECG:
▪ Arrhythmia could be present (commonly atrial fibrillation)
▪ Atrial enlargement
3 Chest X ray:
▪ Heart field: atrial enlargement
▪ Lung field: pulmonary congestion or pleural effusion
4 Echocardiography: check for
▪ Small ventricular cavity with or without wall hypertrophy
▪ Normal systolic function
▪ Diastolic dysfunction
▪ Bi-atrial dilatation
▪ Secondary mitral and tricuspid regurge
▪ Pulmonary hypertension
5 Special investigations
▪ Cardiac MRI to determine the pathology of RCM as cardiac amyloidosis which is a treatable pathology nowadays.
▪ Myocardial biopsy in selected cases
C Treatment:
1 Control of congestion: by diuretics
2 Disease modifying anti-failure treatment:
▪ SGLT2i is recommended in patients with heart failure and preserved systolic function (HFpEF)
▪ ACEI/ ARBs / ARNI/ MRA use in HFpEF is of unclear benefit unless indicated for other reason as control of hypertension
3 Lifestyle modification and controlling risk factors and precipitating factors (same as HF)
4 Management of associated comorbidities (atrial fibrillation)
▪ Details in arrhythmia section
▪ Keep in mind that drugs preferred in RCM and AF are betablockers and Non DHP CaCBs
▪ Digoxin is not preferred with RCM as it could worsen diastolic dysfunction
▪ Don’t forget oral anticoagulation to protect against thromboembolic stroke
5 Specific treatment of cardiac pathology
▪ Refer for specialist centres all RCM cases for CMR evaluation to detect potentially treatable causes as cardiac amyloidosis and iron overload RCM.
Definition of Hypertrophic obstructive cardiomyopathy
- HOCM is idiopathic subaortic stenosis due to hypertrophy of the interventricular septum at the level of left ventricular outflow tract
- Such hypertrophy must be idiopathic not due to pressure overload or myocardial infiltration.
Pathophysiology of Hypertrophic obstructive cardiomyopathy
- HOCM is inherited disorder (autosomal dominant) involves genetic mutation of genes responsible for cardiac muscles
- This will lead to unexplained asymmetrical septal hypertrophy at the level of outflow tract which lead to dynamic left ventricular outflow obstruction
- Left ventricular outflow obstruction depend on left ventricular filling
o Good LV filling (during exercise with good venous return with lower limbs muscles contractions) will push the septum away from mitral valve which in turns decrease the left ventricular outflow obstruction
o Poor LV filling (after stopping the exercise and decrease in the venous return) will make the septum move towards the mitral valve with subsequent increase in left ventricular outflow obstruction
o That is why syncope of HOCM usually occurs after finishing exercise not during exercise. - Left ventricular obstruction is also caused by systolic anterior motion of anterior mitral valve leaflet (SAM) towards the interventricular septum due to venturi effect
- Left ventricular obstruction is responsible for most of syncopal attacks however ventricular arrhythmia is also responsible for considerable number of syncopal attacks
Classification of Hypertrophic cardiomyopathy (B)
- Basal hypertrophic cardiomyopathy (classic HOCM)
- Mid LV hypertrophic cardiomyopathy
- Apical LV hypertrophic cardiomyopathy
Presentation of Hypertrophic cardiomyopathy (B)
- HOCM is asymptomatic in early years of life
- Sudden cardiac death may be the first presentation. Therefore, being autosomal dominant, it is important to ask about family history of sudden death in young ages.
- The patient could present with syncopal attacks either related to
o Palpitations due to ventricular arrhythmia
o Left ventricular outflow obstruction due to decreased left ventricular filling for example with use vasodilators and post exercise.
Management of patients with Hypertrophic cardiomyopathy (Examination) (A+++)
Etiology: Autosomal dominant inherited disorder characterized by mutation in genes encoding myosin, troponin, and tropomyosin which result in disorganized dysfunctional myocardial hypertrophy.
1- General examination
o Mentality
o Vital signs:
▪ Jerky carotid pulse (rapid rise and rapid fall due to interruption of systolic flow of blood from left ventricle to aorta by left ventricular outflow obstruction)
o ABCD
o Regional
▪ Prominent a wave in neck veins in cases of concomitant right ventricular hypertrophy (contraction of right atrial against less compliant hypertrophied right ventricle cause increase in amplitude of a wave)
o Other system
2- Local examination
o Inspection and palpation
▪ Double apex beat due to felt powerful left atrial contraction against less compliant hypertrophied left ventricle
▪ Systolic thrill could be felt at lower sternal border corresponding to subaortic stenosis (left ventricular outflow obstruction)
o Auscultation
▪ Systolic murmur at the first or second aortic area that increase in intensity with maneuvers decreasing left ventricular filling as (standing)
