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Case 3: Anat. Path. Cardiac failure - Coggle Diagram
Case 3: Anat. Path. Cardiac failure
Essential Functions
Outline the essential functions of the Heart
The essential functions of the heart is to:
Cover the metabolic needs of the tissue
To receive all the blood coming back from the tissue
The Pressure-Volume Loop
Describe the purpose of the Pressure-Volume Loop
Pressure-Volume loop represent the relationship between Ventricular Pressure and Volume
The pressure-volume loop is important in understanding the normal cardiac physiology
Explain the Pressure-Volume Loop
Pressure-Volume loop consists of 4 phases:
D-A Phase
Which involves the filling of the Ventricle
A-B Phase
Which involves the Isovolumic contraction of the ventricle
B-C Phase
Which involves the ejection of the blood
C-D Phase
Which involves the Isovolumic relaxation of the Ventricle
Cardiac Output
Outline the Cardiac Output and the factors affecting Cardiac Output
Cardiac Output = Heart rate x Stroke Volume
Heart Rate is controlled by the Autonomic Nervous System
Stroke Volume is controlled by:
Preload
Afterload
Contractility
Define Preload
Preload is the volume of blood in the ventricle at the end of Diastole.
Define Afterload
Afterload is the pressure which the heart has to work against or overcome in order to eject blood.
Changes in any of the factors affecting Heart Rate and Stroke Volume can lead to changes in the Cardiac Output which in turn can affect delivery of blood to the tissues
And if changes are long standing it can lead to Cardiac Failure
Cardiac Failure
Define Cardiac Failure
Cardiac Failure is when the heart is unable to pump blood at a rate sufficient to meet the metabolic needs or requirements of tissues
This result from any structural or functional cardiac disorder, impairing ability of the ventricles to fill with blood or eject blood.
Congestive Cardiac Failure complicates all forms of cardiac disease
In Cardiac failure there is a marked reduction in ejection fraction
Meaning that is that the fraction of end diastolic blood volume ejected from the ventricle during each systolic contraction is less than 40%
Preload
Define Preload
Preload is the volume of blood or fluid present in the ventricles at the end of Diastole
List the Disorders of Preload
Valvular abnormalities such as Mitral Stenosis
Constrictive Pericarditis
Increased Heart Rate
Outline the disorders of Preload
Valvular abnormalities such Mitral Stenosis
In Mitral stenosis, blood CONNOT properly move from the Left atrium into the Left ventricle due to the decreased Valve Luminal Diameter
Therefore, there is excessive blood in the Left atrium and very little blood entering into the Left Ventricle
This directly decreases the Preload on the heart
Constrictive Pericarditis
In Constrictive Pericarditis, the Pericardium is Fibrotic and effectively squeezes down on the heart
This prevents proper Atrial filling
If not enough blood is entering the Left atrium, there will not be enough blood entering the Left Ventricle
Thus decreasing Preload on the heart
Increased Heart Rate
The Atria fill in Diastole
If the heart is beating rapidly there is little time for the Atria and then the Ventricles to fill properly
This decreases the preload on the heart
Contractility
Contractility controls the Stroke Volume of the heart and thus controls the Cardiac Output
Disorders of Contractility
List the disorders of Contractility
Ischaemia/Infarction
Myocarditis
Arrhythmia
Amyloid
Outline the disorders of contractility
Ischaemia/ Infarction
Ischaemic/Infarcted myocytes either do NOT contract properly or do NOT contract at all
This will heavily impact the Heart's Systolic ability depending on the extent of the infarcted area
Myocarditis
Myocarditis is the inflammation of the Heart muscle
Inflammation of the heart muscle can affect cardiac myocyte contraction
Arrhythmias
In order for the heart to contract in a smooth rhythmical manner there needs to be proper cardiac conduction
Normal cardiac conductions is from the Sinoatrial node to the Atrioventricular node, through the Bundle of His and then Left and Right Bundle Branches
An abnormality or short circuit anywhere along the Conduction System will result in abnormal Conduction known as Arrhythmia
And therefore Abnormal Contractility
Amyloid
Amyloid is the accumulation of misfolded proteins in the heart which prevent the cardiac myocytes from contracting normally
Afterload
Define Afterload
Afterload is the pressure that the heart has to overcome in order to eject blood.
List the disorders of Afterload
Increased Arterial Resistance
Valvular abnormalities such Aortic Stenosis
Other disorders
Outline the Disorders of Afterload
Disorders of Afterload
Increased Arterial Resistance
Increased Arterial Resistance is when there is increased pressure in the systemic vessels (Arteries) directly after the Aorta
This may be due to Luminal Narrowing such as:
Atherosclerotic plaque narrowing the arterial lumen
Vasoconstriction
Aortic coarctation
Therefore, Increased Arterial Resistance increases Afterload
Valvular abnormalities such Aortic Stenosis
A valvular abnormality causing a pressure overloaded state such as Aortic stenosis causes an increase in Afterload
This is due to the increased pressure that needs to be generated in order to eject blood from the Left ventricle through a Narrow Aortic Valve
Other conditions that may contribute include:
High Output States: Pregnancy, Anaemia, Sepsis, Beriberi due to Thiamine deficiency
Cardiac tumours such as Atrial Myxoma
Causes of Congestive Cardiac Failure
List the most common causes of Congestive Cardiac Failure
The most common causes of congestive cardiac failure are:
Systemic Hypertension
Ischaemic Heart Disease
Valvular Heart Disease
Chronic Lung Disease
Clinical Classification of Cardiac failure
Outline the Clinical Classification of Heart/ Cardiac Failure
Heart/ Cardiac Failure can be classified according to 4 main branches:
Based on the Course of the Disease
Based on Location
Based on Output
Based on Impaired Function
These 4 main branches have further sub-branches that follow:
Based on the Course of the Disease
Acute Cardiac Failure
Chronic Cardiac Failure
Based on the location
Left-sided cardiac Failure
Right-sided cardiac Failure
Biventricular cardiac Failure
Based on Output
Low-Output Cardiac Failure
High-Output Cardiac Failure
Based on Impaired Function
Systolic Failure
Diastolic Failure
Classification: High-Output Cardiac Failure vs Low-Output Cardiac Failure
Differentiate between High-Output Cardiac Failure and Low-Output Cardiac Failure
High-Output Cardiac Failure
In High-Output Cardiac Failure, the cardiac output is higher then normal due to increased peripheral/metabolic demand that increases the myocardial oxygen demand
When the heart cannot cope with the Cardiac stress then activation of compensation mechanisms lead to:
Volume expansion &
Further Cardiac Stress
High-Output Cardiac failure occurs in the following conditions:
Hyperthyroidism
Beriberi
Pregnancy
Severe anaemia
Low-Output Cardiac Failure
In Low-Output Cardiac Failure, there is a low cardiac output, this is most commonly caused by depressed ejection fraction.
Low-Output Cardiac Failure occurs in the following conditions:
Dilated cardiomyopathy
Chronic Hypertension
Valvular Heart Disease
Compensatory/Adaptive Mechanisms of Cardiac failure
List the Compensatory/Adaptive mechanisms of Cardiac Failure
Compensatory/Adaptive mechanisms of Cardiac Failure:
Activation of the Sympathetic Nervous System
Activation of the RAA (Renin-Angiotensin-Aldosterone) system
Ventricular Hypertrophy and/or Dilation
Signs and Symptoms of Left Cardiac Failure
Signs and Symptoms of Left-Sided Cardiac Failure occur above the Diaphragm
List the Signs and Symptoms of Left-Sided Heart Failure
Fatigue
Confusion
Restlessness
Cyanosis
Orthopnea
Exertional Dyspnea
Tachycardia
Pulmonary Congestion/ Pulmonary Oedema resulting in
Coughing
Crackles
Wheezing
Blood tinged sputum
Tachypnea
Elevated Pulmonary Capillary Wedge Pressure
Paroxysmal Nocturnal Dyspnea
Outline Pulmonary Oedema due to Left-sided Cardiac Failure
Pulmonary Oedema due to Left-sided Cardiac Failure occurs when the pressure in the Atrium is lower than the pressure in the Aorta
Causing the blood to track back into the Lungs
Pulmonary Oedema begins with an increased filtration through the loose junctions of the Pulmonary capillaries
As the Intracellular pressure increases, normally tight junctions between the alveolar cells, permit alveolar flooding to occur
Resulting in a displaced Apex beat due to Cardiomegaly resulting in crepitations in the Lungs
Pathology of Left Heart Failure
Outline the Pathology of Left-Sided Cardiac Failure in the Lungs
In the lungs, Left-Sided Cardiac Failure causes the following:
Pulmonary Oedema
Pulmonary Congestion
Alveolar Fluid Accumulation
Outline the Macroscopy of Pulmonary Oedema due to Left-Sided Cardiac Failure
Lungs are enlarged
Frothy secretions on cut surface of the Lungs
Outline the microscopy of Pulmonary Oedema due to Left-Sided Cardiac Failure
Caption:
Transudate in Alveolar Lumen
Dilated capillaries in Alveolar wall
Thickened Alveolar wall with Dilated Capillaries and Interstitial edema
Numerous Hemosiderin Laden Macrophages called Siderophages
Also known as Cardiac Failure cells
Macrophages contain a Hemosiderin Pigment
Located within the Alveoli
And are produced in patients with Left-Sided Cardiac failure
Outline the Pathology of Left-Sided Cardiac Failure in the Heart
In Left-Sided Cardiac Failure, the heart may show features of:
Macroscopy: Cardiac Hypertrophy/ Dilation of variable degrees
Microscopy: Myocyte hypertrophy and Interstitial Fibrosis
Signs and Symptoms of Right-Sided Cardiac Failure (Cor Pulmonale)
Signs and Symptoms of Right-Sided Cardiac Failure occur below the Diaphragm
List the Signs and Symptoms of Right-Sided Cardiac Failure
Fatigue
Increases Peripheral Venous Pressure
Ascites
Enlarged Spleen and Liver
Pitting Edema
Weight Gain
Distended Jugular veins
May be secondary to chronic pulmonary problems
Anorexia and Complaints of GI Distress
Cor Pulmonale (Right-Sided Cardiac failure)
Outline the Cor Pulmonale
Cor Pulmonale is the Hypertrophy of the Right Ventricle resulting from a Primary Respiratory Disease affecting the structure and/or function of the Lung
In Cor Pulmonale the Right Ventricle is Hypertrophic or Dilated
Cor Pulmonale is most commonly due to Chronic Obstructive Pulmonary Disease (COPD)
Outline the effects of Chronic Obstructive Pulmonary Disease
COPD causes a normal cardiac output to be pumped in a smaller number of vessels
Therefore, most of the vessels are destroyed as part of the Pulmonary Disease
Causing an increased pressure in the remaining vessels
Also Hypoxia causes reflex vasoconstriction with worsening of increased pressure.
The Pathology of Right-Sided Cardiac Failure
Outline the Pathology of Right-Sided Cardiac Failure
Right-Sided Cardiac failure may be associated with:
Pitting Oedema
Congestive Splenomegaly
In the Liver and Portal system it may be associated with Congestive Hepatomegaly
The Cut Surface of the Liver will have a Nutmeg Appearance (Nutmeg Liver)
This may result in Cardiac Cirrhosis
Mode of Death associated with Cardiac Failure
Outline the Mode of Death associated with Cardiac Failure
Arrhythmias
Myocardial Infarction
Metabolic Disturbances
Thromboembolism
With or Without superadded infections
Explain oedema with respect to cardiac failure. Include the role of the lymphatic system
Peripheral oedema is an abnormal accumulation of fluid under the skin or within body cavities causing swelling of the area or indentations on firm palpitations
Increased venous hydrostatic pressure causes a transudative process in which fluid is pushed out of vessels into the interstitium
It is normally seen in the context of right heart failure.
There are a few factors contributing to this:
Increased plasma volume: Decreased cardiac output in either left or right heart failure leads to renal hypoperfusion. In response to this the renin-angiotensin-aldosterone system is activated.
This leads to the retention of salt and water which in turn leads to increased Venous and capillary hydrostatic pressure
Raised venous pressure: Ventricular dysfunction leads to increased end systolic/end-diastolic pressures
These pressures are transmitted back to the atrium and then to the venous system which increases venous and capillary hydrostatic pressure.
Increased hydrostatic pressure forces fluid out of venous vessels into the surrounding tissues which causes swelling.
The lymphatic system is unable to keep up with the task of reabsorbing additional interstitial fluid and oedema develops.
