Cardio 3 Flashcards
What is the definition of heart failure?
clinical syndrome with symptoms/signs caused by a structural or functional cardiac abnormality AND confirmed by elevated natriuretic peptide levels or evidence of pulmonary or systemic congestion
What is the equation for cardiac output?
CO = HR x SV
What is cardiac output?
the volume of blood in liters pumped form ventricles per minute
What is the cardiac output goal?
maintenance of adequate tissue perfusion
The MAP equation is __
MAP = __ diastole + __ systole
MAP = SV x HR x SVR
2/3 diastole
1/3 systole
Heart rate is affected by:
Autonomic innervation
Hormone regulation
Fitness level
Age
Stroke volume is affected by:
Preload
Afterload
Contractility
Heart size (gender)
Fitness level
Age
Preload:
“stretch”
Volume of blood inside ventricles during diastole
Quantify: left ventricle end-diastolic volume (LVEDV or EDV
Afterload:
“squeeze”
esistance ventricles must overcome to force blood into systemic circulation
Quantify: systemic vascular resistance (SVR), pulmonary vascular resistance (PVR), end-systolic volume (ESV)
Contractility:
“strength”
Contraction of the myocardium through the actin-myosin cross bridge cycle
Quantify: ejection fraction (EF)
EF = (EDV - ESV) / EDV : stroke volume
Preload is affected by:
Heart rate
Ventricle compliance
Atrial contraction
Venous/aortic pressure
Total blood volume
Afterload is affected by:
Aortic pressure
Systemic vascular resistance
Ventricle wall thickness
Ventricle radius
Contractility is affected by:
Sympathetic nervous system
Heart rate
Ca2+
Rhythm
What is an average cardiac output for an adult male?
CO = HR x SV
70 bpm x (70ml/1000)
= 4.9 L/min
(4-8 L/min)
LVEDP is a surrogate for __
EDV
Decrease in after load or an increase in contractility leads to a HIGHER/LOWER SV
Higher SV
Increase in after load or decrease in contractility leads to a HIGHER/LOWER SV
Lower SV
CVP is the __ pressure
right atrial pressure
LVEDV is the __ pressure
Pulmonary-Capillary Wedge pressure
What can impact intracardiac pressures?
Heart failure (hypervolemia)
Pulmonary arterial hypertension
Pleural effusion
Cardiac tamponade
Hypovolemia
Shock
HFrEF is due to __ failure
systolic (heart contraction)
HFpEF is due to __ fialure
diastolic (heart relaxation)
HFrEF is due to:
Loss of __
__ ventricles
__ dysfunction
Loss of intrinsic contractility
Overstretched: weak and thin ventricles
Pumping (systolic) dysfunction
HFpEF is due to:
Failure of __
__ ventricles
Reduced __
__ dysfunction
Failure of ventricles to relax properly
Thick and stiff ventricles
Reduced ventricle volume in diastole
Filling (diastolic) dysfunction
Classification of heart failure is based on the ejection fraction of the __
left ventricle
What are the three classifications and LVEF levels of heart failure?
HFrEF: </=40%
HFmrEF: 41-49%
HFpEF: >/=50%
What is cardiomyopathy?
An acquired or inherited disease of the myocardium associated with mechanical or electrical disfunction, leading to an enlarged/rigid heart muscle
In hypertrophic cardiomyopathy, ventricles become __
larger and thicker
In dilated cardiomyopathy, ventricles become __
weaker and larger
In restrictive cardiomyopathy, ventricles __
stiffen, but do not thicken
In left ventricular non-compaction, the LV becomes __
thick/spongy
In arrythmogenic right ventricular dysplasia __ leads to arrhythmias
fibrous tissue
What are examples of Primary non-ischemic cardiomyopathies?
Genetic:
HCM
Congenital heart defect
Ion channel disorders
ARVC/D
LVNC
Acquired:
Peripartum
Takotsubo
Inflammatory (myocarditis)
Arrhythmias
Mixed:
DCM
Restrictive
What are ischemic cardiomyopathy examples?
CAD
ACS
What are examples of secondary non-ischemic cardiomyopathies?
Infiltrative
Neuro-muscular
Obesity
Hypertension
Toxicity
Auto-immune
Anemia
Endocrine
Electrolyte imbalance
Chronic lung disease
Cardiac tumor
Inflammatory
CKD
Pericardial disease
VHD
What are the most common etiologies of HFrEF?
CAD/ACS
Hypertension
What is the most common etiology if HFpEF?
Hypertension
What is involved in the pathophysiology of HFrEF?
SNS: neurohormonal activation
Frank-Starling mechanism
RAAS: neurohormonal activation
Ventricular hypertrophy and remodeling
Compensatory mechanisms in heart failure are initiated by __
acute reductions in blood pressure or reduced renal perfusion (due to low CO)
What is the purpose of the compensatory mechanisms in heart failure?
To provide short-term support to maintain circulatory homeostasis
Long activation of heart failure compensatory mechanisms results in __
functional, structural, biochemical, and molecular changes in the heart
Further stress results in deterioration of ventricular function
What neurohormones are involved in the SNS activation leading to heart failure? What effects to they precipitate?
NE: tachycardia, vasoconstriction, contractility
AVP: vasoconstriction, water retention
Renin: vasoconstriction, water retention
What is the result of SNS activation leading to heart failure?
Decrease in CO causes unloading of baroreceptors, which decrease parasympathetic tone
Increase in sympathetic tone which releases NE, renin, and AVP
Decrease in Beta1 receptor sensitivity, reduces stimulation over time
What are the results of cardiomyocyte contraction in heart failure?
Increase in HR, decrease in diastole time, increase in intracellular Ca2+
Increase in actin-myosin interaction, increase in rate of contraction
Decrease in lusitropy (ability to relax)
Creates greater filament interaction during systole (force), increased wall tension
Which neurohormones are involved in the RAAS activation that leads to heart failure? What are their effects?
Angiotensin II: Na and water retention, stimulates aldosterone release
Aldosterone: Sodium and water retention, cardiac fibrosis
What is the Kallikrein-kinin system?
Cross talks with RAAS to cause vasodilation
Bradykinin increases release of other vasodilatory molecules
What are the types of natriuretic peptides?
Atrial NP: high affinity, short half-life
Brain or B-type: lower affinity but longer half-life
N-terminal: biologically inactive, longest half-life
What is the purpose of natriuretic peptides in response to volume overload?
To promote natriuresis/diuresis and inhibit RAAS and SNS
Chronic activation of hemodynamic and neurohormonal compensatory responses leads to __ (ventricular remodeling).
Eccentric hypertrophy
Change in ventricle composition
Oxidative stress and inflammatory cytokines
Altered myocardial contraction
Alterations in geometry
What is the benefit of increased preload volume (Frank-Sterling) response?
Increased stroke volume (CO)