Congestive Heart Failure Part 1 Flashcards
Epidemiology of Heart Failure
In 2007 the AHA estimated 5.7 million people in the US and 23 million world wide have heart failure.
Risk increases with age, coronary heart disease, cigarette smoking, HTN, Obesity, Diabetes, Valvular Heart Disease, Race (68% vs 49% in African Americans compared to Caucasians)
Causes of Heart Failure (4)
Ischemic Heart Disease 40% Dilated Cardiomyopathy 32% Primary Valvular Disease 12 % Hypertensive Heart Disease 11% Other 5%
Developing Countries causes of HF (6)
Rheumatic Fever Valvular 8% Peripartum Cardiomyopathy Idiopathic Cardiomyopathy 28% Hypertension 33% Ischemic Heart Disease 9%
Action Potential
The creation of the the action potential in one area results in the creation of another action potential in the adjacent area, and repeats.
Linear propagation occurs because the myocytes along muscle fibers are electrically continuous.
For the above two reasons the action potential results in a “wave.”
Muscle Contraction
Tropomyosin physically blocks the interaction between the thick and thin filaments
Three types on troponin I, T and C
C binds calcium which allows the thick and thin filaments to interact.
I inhibits the ATPase of actomycin and helps calcium bind to C
T attaches the troponin complex to actin and tropomyosin, blocks the actin-myosin binding site at rest
Calcium in HF
Ca is found in the sarcoplasmic reticulum
Low pH decreases the ability for calcium to bind to troponin C resulting in decreased contractions.
Heart failure
Calcium influx results in decreased efflux from the SR, resulting in decreased contractile strength and poor relaxation
Normal Left Ventricular Pressure-Volume Relationship
When thinking about this, think of a spring.
Volume enters the LV and at the end of diastole the LV fibers are stretched.
This Stretch is determined by the resting force, myocardial compliance, and how much filling from the L atria. This distension force is PRELOAD.
CONTRACTILITY is the force generated by the myocardium
AFTERLOAD the resistance the LV works against during systole.
Frank Starling relationship
EDV (preload) vs SV (CO + HR)
Improve the preload and the SV will improve (to a point)
Afterload
The resistance that ventricle meets during systole.
In a nml heart the SV changes minimally to changes in afterload.
In the failing heart these changes are enhanced.
Contractility
The ability for each myocyte to contract ( a function of calcium)
Definition of Heart Failure
Clinical syndrome of the inability of the heart to keep up with the demands on it and, specifically, failure of the heart to pump blood with normal efficiency
Two types of HF that can effect both the left side and the right side
Systolic
Diastolic
Systolic Dysfunction (2)
Decreased myocardial contractility.
Think of the spring where the coils are too far pulled apart and they lost there “springiness.”
Issues with Systolic Dysfunction (5)
Decreased contractility results in decreased SV which results in decreased CO.
Neurohormone response to increase contractility and HR to maintain homeostasis.
Kidneys hold onto sodium resulting on water retention and volume expansion to maintain preload
Calcium looses its affinity of troponin C in vitro possibly from muscle stretch at the sarcomere level.
Cardiac myocyte is nml diameter and increased in length. (no change in LV wall thickness and increased in LV volume)
Diastolic Dysfunction
Diastolic Heart Failure is when the pt has clinical signs of heart failure in the setting of normal ejection fraction.
Problems with Diastolic Dysfunction (7)
SV is preserved but an increase in end diastolic pressure, resulting from decreased compliance to receive a certain amount of volume.
Generally a concentric pattern of LV remolding and a hypertrophic process characterized by
A normal or near nml EDV
Increased Wall Thickness
An increased ratio of myocardial mass to cavity volume
An increased ratio of wall thickness to chamber radius
Cardiac myocyte is thickened with no change in length. (change in LV wall thickness and no change in LV volume)
Neurohumoral Response (3)
Body compensates for decreased CO in order to maintain homeostasis by:
Maintain systemic vasoconstriction
Increase contractility and HR by improving volume expansion.
Different Pathways of Neurohumoral Response
Renin-angiotensin-aldosterone system
Angiotensin II increases sodium reabsorption and causes systemic and renal vasoconstriction and can cause pathological remodeling
Antidiuretic hormone (volume expansion)
Atrial Natriuretic Peptide (vasodilator)
Nitric oxide (vasodilator)
Endothelin (vasoconstrictor)
Sympathetic nervous system
Catecholamines
Norepinephrine (improve contractility, vasoconstriction and HR)
Can lead to myocyte pathological remodeling
Complications of Neurohumoral Response (4)
Elevated Diastolic pressure to the atria and pulmonary/systemic venous circulations resulting in pulmonary congestion and edema
Increased afterload in an attempt to vasocontsrict the peripheral systemic system.
Catecholamines used to increase contractility and HR increase risk for coronary ischemia.
Catecholamines and Angiotensin II promote apoptosis of myocytes.
Right Sided Heart Failure
Known as Cor Pulmonale when cause by pulmonary HTN that is associated with lung disease, primary pulmonary HTN, OSA, or chest wall abnormalities (kyphoscoliosis)
L side failure can “spill over” into the R sided but it is NOT called Cor Pulmonale.
Manifestations of Right Sided Heart Failure (8)
Slow and progressive unless PE DOE Fatigue Syncope Exertional angina Anorexia Hepatomegaly JVD Split S2
Right Sided Failure Treatment (7)
Treat the underlying cause Pulmonary HTN PE COPD OSA L sided failure
No Digoxin as it has no evidence that it helps and may have deleterious effects
If in cardiogenic shock attempt IV inotropic agents (dobutamine and milrione)
Cardiomyopathy
are heterogeneous group of diseases of the myocardium associated with mechanical and/or electrical dysfunction that usually (but not invariably) exhibit inappropriate ventricular hypertrophy or dilatation and are due to a variety of causes that frequently are genetic, either are confined to the heart or are a part of generalized systemic disorders, often leading to cardiovascular death or progressive heart failure related disability.”
5 classes based on anatomy and physiology for Cardiomyopathy
Dilated Hypertrophic Restrictive Arrhythmogenic Right Ventricular Unclassified
2 Types of Cardiomyopathy
Primary
Genetic or acquired
Secondary
When other organ systems are involved
Based on specific cardiac or systemic disorders for Cardiomyopathy (7)
Ischemic Valvular HTN Inflammatory Metabolic Toxic Genetic
