L6 Cardiac Failure, Cardiomyopathies, Myocarditis Flashcards
___________: The volume of blood pumped by the left ventricle in one heart beat.
Influenced by?
Stroke Volume: The volume of blood pumped by the left ventricle in one heart beat
SV is controlled/influenced by:
- Preload
- myocyte contractility
- afterload
- number and size of myocytes
- heart architecture
- synchronous function of the atrias and ventricles
- arrythmias will cause abnormal atrial/ventricular filling
__________: the volume of blood pumped by the heart in one minute
Cardiac Output: the volume of blood pumped by the heart in one minute
Cardiac Output (CO) = Stroke Volume (SV) x Heart Rate (HR)
The amount of ventricular stretch at the end of the diastole.
Preload: left ventricular end-diastolic pressure (LVEDP)
Amount of resistance the left ventricle must overcome to open the aortic valve and push the blood volume out into the systemic circulation
Afterload: AKA systemic vascular resistance (SVR)
State in which the heart is unable to pump blood at the required rate
CONGESTIVE CARDIAC FAILURE (CCF)
Causes of Congestive Heart Faiulre
-
Causes:
- Damaged myocardium
- severe ischemia/infarct
- Obstruction to flow
- Aortic stenosis (blockage)
- hypertension
- Regurgitant flow
- mitral or aortic valve regurgitation
- Cardiac conduction disorders (Heart block or arrhythmias)
- Damaged myocardium
Systolic vs. Diastolic Dysfunction contributing to Congestive Heart Failure
-
Systolic dysfunction: Forward direction failure
- insufficient blood volume is being pumped forward
- poor organ perfusion → Hypoxia
-
Diastolic dysfunction: Backward direction failure
- insufficient blood volume enters the ventricle during diastole
- Vascular congestion
- Pulmonary and peripheral Congestion
- Pulmonary and peripheral Edema (excess of watery fluid in the cavities or tissues)
- Pulmonary and peripheral Congestion
In most cases of heart failure, patients present with _______________.
In most cases of heart failure, patients present with combined both right and left-sided heart failure with the clinical and morphological features of each
Common Clinical Features of Left Sided Heart Failure?
-
Common Clinical Features of Left Sided Heart Failure:
- Dyspnea
- Orthopnea (shortness of breath while lying flat)
- Paroxysmal nocturnal dyspnea (PND) - dyspnea only at night
- Pulmonary Congestion/ Oedema (crackles/crepitation on chest auscultation)
Common Clinical Features of Right Sided Heart Failure?
-
Common Clinical Features of Right-Sided Heart Failure
- Peripheral Oedema (ankle -, leg, sacral oedema, due to increased hydrostatic pressure)
-
Pleural Effusion (Hydrothorax)
- Accumulation of excessive fluid in the pleural space that surrounds each lung
- Jugular venous distention and elevated jugular venous pulse
- Splanchnic congestion (Hepatosplenomegaly)
- Ascites- Abdominal Fluid accumulation
Adaptive Mechanisms to Heart Failure?
- Myocardial Hypertrophy
-
Frank-Starling mechanism:
- Increased preload (dilation) leads to increased contractility
- Increased volume stretches the myocardial wall causing more forceful contractions (Frank-Starling mechanism)
- Increases calcium sensitivity of myofibers
- Causes a greater number of actin-myosin cross-bridge formation
- Greater contractility => Increased stroke volume
- Increased volume stretches the myocardial wall causing more forceful contractions (Frank-Starling mechanism)
- Increased preload (dilation) leads to increased contractility
-
Neurohumoral systems activation:
- Release of norepinephrine/noradrenaline (increases HR and augments contractility)
- Renin-angiotensin-aldosterone system activation
- Release of atrial natriuretic peptide
Describe the Frank-Starling Mechanism?
-
Frank –Starling mechanism:
- Increased preload (dilation) leads to increased contractility
-
STARLING’S LAW: Stroke volume of heartincreasesin response to anincreasein the volume of blood filling the heart at the end of diastole
- The increased volume stretches the myocardial wall causing more forceful contractions (Frank-Starling mechanism)
- Increases calcium sensitivity of myofibers
- Causes greater number of actin-myosin cross bridge formation
- Greater contractility => Increased stroke volume
- The increased volume stretches the myocardial wall causing more forceful contractions (Frank-Starling mechanism)
STARLING’S LAW: Stroke volume of heart ________ in response to an ________ in the volume of blood filling the heart at the end of _______
STARLING’S LAW: Stroke volume of heartincreasesin response to anincreasein the volume of blood filling the heart at the end ofdiastole
Distal effects of left cardiac failure are seen most prominently in ______
Clinical Symptoms?
-
Lungs:
- Backward/retrograde pressure from left heart/pulmonary vein
- Perivascular transudate (discharge)
- Widening of institution space
- Edema fluid enters alveolar sacs
- Pleural effusion
-
Clinical signs & symptoms of above:
- Dyspnoea
- Cough
- Orthopnoea (shortness of breath when laying down)
- paroxysmal nocturnal dyspnoea
Left sided heart failure effects seen in _______________ due to lack of forward push/decreased cardiac output
-
Kidneys:
- Deceased renal perfusion→ Activation of renin-angiotensin-aldosterone system →induces water/salt retention
- → expansion of the blood volume and the interstitial fluid volume
- promotes pulmonary congestion/oedema!
-
Brain:
- Changes seen in severe/advance state:
- decreased cerebral perfusion
- cerebral hypoxia
- confusion
- Changes seen in severe/advance state:
Right Sided Cardiac Failure is also known as _________
Right-Sided Cardiac Failure is also known as ‘Venous Congestion Syndrome’
left-sided cardiac failure tends to cause right-sided cardiac failure → increased pulmonary circulation pressure causes increased right heart pressure
Rights sided Cardiac failure is associated with what kind of congestion?
Symptoms?
Minimal pulmonary congestion (and thus minimal respiratory symptoms) but massive systemic congestion
Symptoms:
-
Liver/portal system:
- Slight increase in size/weight of liver to congestion of the liver tissue.
- Surface looks like Nutmeg
- Spleen:
- Increased size, feels tense, marked sinusoidal dilatation.
-
Subcutaneous tissues:
- Peripheral oedema/swelling
- especially lower limb (ankles/pre-tibial area) sacral region
- Pleural & pericardial effusions
- Ascites: Fluid within abdominal/peritoneal cavity
_____________: Manifests due to the right ventricle being burdened by pressure due to increased resistance of the pulmonary circulation. Leads to right ventricular _______ and ____
Pure Right Sided Cardiac Failure –COR PULMONALE**: Manifests due to the right ventricle being burdened by pressure due to increased resistance of the pulmonary circulation. Leads to right ventricular **dilation** and **hypertrophy
________________;
- Massive pulmonary embolism
- right ventricle cannot pump blood into the occluded pulmonary arteries
- right ventricle dilates until it can’t contract
- Immediate cause of death in massive PE.
Acute Cor Pulmonale:
- Massive pulmonary embolism
- right ventricle cannot pump blood into the occluded pulmonary arteries
- right ventricle dilates until it can’t contract
- Immediate cause of death in massive PE.
________________:
- Due to chronic severe pulmonary hypertension.
- Disorders?
Chronic Cor Pulmonale:
- Due to chronic severe pulmonary hypertension.
- Disorders include:
- COPD
- emphysema
- Pulmonary interstitial fibrosis
- PE
- Pulmonary arteritis
- cystic fibrosis
- neuromuscular disorders affecting chest movement
- disorders inducing pulmonary vascular constriction
Primary vs. Secondary Cardiomyopathy
Cardiomyopathy: Disease of heart muscle
- Primary: congenital or no known cause)
- Secondary: have known causes, i.e. ischemic, hypertension).
Characteristics/Causes of Dilated Cardiomyopathy?
CHARACTERISTICS
- Most common cardiomyopathy
- Characterized by cardiac hypertrophy, dilatation, and CONTRACTILE/SYSTOLIC DYSFUNCTION
- Stasis: Mural thrombi: Source for systemic thrombo-emboli
- Valves are anatomically normal but dilation of ventricle can lead to mitral regurgitation as valves too far to properly close
CAUSES:
- Idiopathic
- Myocarditis
- Alcohol
- Pregnancy/Peripartum: Occurs in third trimester or post-partum.
- Genetic
Most Common Cardiomyopathy?
Dialated
Characteristics/Causes/Signs of Hypertrophic Obstructive Cardiomyopathy
Characteristics
- Typically septal/left ventricular hypertrophy
- Characterized by impaired ventricular compliance & impaired diastolic filling = DIASTOLIC DYSFUNCTION
- associated with severe disease & high incidence of sudden death.
Cause:
-
Genetic: About 50% cases are familial autosomal dominant,
- beta-myosin heavy chain gene mutation
- Clinical/morphologic/prognostic features vary greatly
Signs
- Exertional dyspnea: Due to decreased cardiac output & secondary increase in pulmonary pressure
- Harsh systolic ejection murmur: ventricular outflow tract obstruction
- Angina type pain
Major problems:
· Atrial fibrillation with mural thrombi formation (risk of systemic emboli)
· cardiac failure
· arrhythmias
Characteristics/Causes of Restrive Cardiomyopathy
- Decrease in ventricular compliance → impaired ventricular filling during diastole → DIASTOLIC DYSFUNCTION.
- Contractile function not affected
- The relaxation of the heart muscle is abnormal
-
CAUSES:
- Primary/idiopathic
- Secondary to Radiation treatment (myocardial fibrosis)
- Amyloidosis (deposition of amyloid in the myocardium),
- Sarcoidosis (non-caeseating granulomas in the myocardium),
- Metastatic tumour
- Loeffler endomyocarditis (endomyocardial fibrosis & eosionophilia & large mural thrombi)
-
Gross Pathology:
- Ventricles are NOT dilated
- Myocardium is FIRM & STIFF
- Both Atrial cavities are dilated
Primary Cardiomyopathies (4)
Primary cardiomyopathies include:
1. Dilated
2. Hypertrophic Obstructive (HOCM)
3. Restrictive
4. Arythmogenic right ventricular dysplasia (ARVD); Fibro-fatty infiltrate of right ventricle with interstitial fibrosis. Genetic basis
What is MYOCARDITIS?
- A primary inflammatory process of myocardium
- Can occur at any age
Causes of Myocarditis?
-
INFECTIOUS: Most common cause
- Viruses (majority of cases) with infants
- Frequently implicated viruses are Coxsackie A & B, ECHO virus, influenza A & B
- Occurs days/weeks after a primary viral infection elsewhere, such as an upper RTI
-
Mechanisms of myocyte damage:
- Direct viral cytotoxicity
- The virus induces cell-mediated immune reaction that attacks myocytes harboring virus/viral antigens
- immunosuppressed susceptible to bacteria, fungi, protozoa
- Viruses (majority of cases) with infants
-
IMMUNE-MEDIATED REACTIONS:
- Post streptococcal infections/Rheumatic fever
- Drugs/Medications
- hypersensitivity reaction to a drug {penicillin)
- direct drug toxicity to the heart {e.g. doxorubicin}
- PHYSICAL AGENTS: Radiation
-
SARCOIDOSIS
- disease involving abnormal collections of inflammatory cells that form lumps known as granulomata
Signs/Symptoms of Myocarditis?
- Vary from extremes of asymptomatic to sudden onset of Cardiac Failure
- Shortness of Breath
- Palpitations
- Fatigue
- Precordial discomfort
- mild fever (if cause is infectious)
- Patients can recover without any long term sequelae
- sudden death also possible due to
- Arrhythmia
- CCF (from dilated cardiomyopathy)
Gold Standard of Myocarditis Diagnosis?
Endomyocardial biopsy is the gold standard to diagnose myocarditis
- Myocarditis is a focal disease so four to five biopsy samples must be obtained from more than one area of the right ventricular (RV) septum
For a diagnosis of myocarditis both _____________ and _________ need to be present. _____________ is also an indicator
For a diagnosis of myocarditis, both inflammatory cells & myocyte necrosis are needed to be present.
Tropinin is a sign of myocardial injury
______ is a sign of myocardial injury
Tropinin is a sign of myocardial injury
