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
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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
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Systolic dysfunction: Forward direction failure
- insufficient blood volume is being pumped forward
- poor organ perfusion → Hypoxia
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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?
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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)
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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?
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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?
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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
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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: