Heart failure & circulatory shock Flashcards
What is heart failure?
Heart Failure is a clinical syndrome that occurs when the heart is unable to pump adequate blood to meet the metabolic demands of the body
Who is at greater risk for heart failure?
Primarily the elderly Vessel stiffness ASHD Hypercholesterolemia Hyperlipedemia Decreased estrogen production for women
Evolution of Our Understanding of HF
CHF as a disorder of excessive sodium & water retention (cardio-renal model)
CHF as a hemodynamic disorder (reduced CO or AL)
HF as a neurohormonal model
What is preload?
“End -diastolic volume”
Determined by venous return to the heart
What is afterload?
Amount of force needed to eject filled heart
Determined by SVR and ventricular wall tension
Contractility
Performance of cardiac muscle
What is systolic heart failure and its causes?
- Impaired ejection of blood
- Presence of S&S of HF with an EF
Ejection Fraction (EF)
The % of blood ejected from the LV during systole
Normal EF = 55-70%
If the LV has 100ml @ end-diastole, and the stroke volume is 70ml (leaving 30ml still in the LV after systole), then….
70/100 = 70%
What is diastolic heart failure & and its causes?
Who is at risk?
- Impaired filling during diastole
- Presence of signs and symptoms of HF in the absence of systolic dysfunction (LVEF > 40%)
Myocardium is “stiff” (and often hypertrophied) and does not relax normally after contraction
Causes - Impaired ventricular stretch pericardial effusion, pericarditis, amyloidosis)
- Increased wall thickness hypertrophy, myopathy)
- Delayed diastolic relaxation (aging, CAD)
Aggravated by tachycardia
At Risk: women, obesity, HTN, DM
Left-side heart failure (LV dysfunction)
- Decreased CO
- Pulmonary congestion
LV Dysfunction Manifestations (CNS, CVS, Renal)
- Decreased CO
CNS - Fatigue, weakness, confusion, dizziness (worsens over day)
CVS - Hypotension, angina, tachycardia, palpitations, pallor, weak peripheral pulses, cool extremities, S3/S4
Renal - Oliguria (daytime d/t gravity)
LV Dysfunction Manifestations (pulmonary congestion)
- SOB (initially during exertion/orthopnea/PND)
- Cough, “cardiac asthma” (worse at night)
- Inspiratory crackles/expiratory wheezes
- Tachypnea
- Frothy/pink sputum (pulmonary edema) fluid overload in the alveoli
Right sided failure (RV dysfunction)
-systemic congestion
RV Dysfunction Manifestations
> Systemic Congestion
- JVD/elevated CVP
- Enlarged liver and spleen
- Dependent edema
- Ascites
- Polyuria @ night
- Weight gain
- Hepatojugular reflux (HJR) – push down on liver to see if fluid in jugular vein changes
- BP changes (elevated or decreased)
Compensatory Mechanisms in HF (Frank-Starling Mechanism & Sympathetic Nervous System)
> Frank-Starling Mechanism
+ Increased ED volume (preload) will increase stroke volume
- Stretch increases wall tension, increasing oxygen requirements
> Sympathetic Nervous System
+ Increase in circulating catecholamines increase HR, contractility, PVR, SV, CO
- Increased workload
Compensatory Mechanisms in HF (Renin-Angiotension-Aldosterone System)
+ Increased concentration of renin, angiotensin ll, & aldosterone d/t decreased renal perfusion
Increased preload, increased workload
Compensatory Mechanisms in HF (Natriuretic Peptide (ANP & BNP))
+ Released in response to stretch, pressure, fluid overload (promote diuresis)
Decreases preload decreases CO