HF Patho

Question 1

Heart Failure Definition

Answer 1

• Signs and symptoms of intravascular and interstitial volume overload resulting in symptoms of SOB and/or edema
• Manifestations of inadequate tissue perfusion resulting in symptoms of fatigue and/or poor exercise tolerance

Question 2

Cardiac Output

Answer 2

HR * SV

• Normal: 5-8 L/min
• SV = EDV - ESV
• HR: depends on SNS and PNS
• SV: depends on preload, afterload, and contractility

Question 3

Preload

Answer 3

• Left ventricular end-diastolic pressure (LVEDP)

- Measured as pulmonary capillary wedge pressure (PCWP)

Question 4

Afterload

Answer 4

-Systemic vascular resistance (SVR)

Question 5

Contractility

Answer 5

• Ability of contractile elements to interact and shorten against a load
• (+)/(-) inotropy

Question 6

Blood Pressure

Answer 6

CO * TPR

Question 7

LVEF

Answer 7

• Left ventricular ejection fraction
• SV/EDV
• Normal: 50-70%
• Requires objective measure of systolic function (ECHO, RNV, cardiac catheterization)

Question 8

Angiotensin II Elevation in HF

Answer 8

• Myocyte hypertrophy => remodeling, myocardial dysfunction
• Increased PAI-I levels => thrombosis
• Increased proximal Na+ reabsorption => Increased ECF volume, pulmonary/peripheral edema
• Increased thirst => dilutional hyponatremia
• Increased pituitary AVP release => vasoconstriction, water retention
• Increased pre-synaptic NE release => tachycardia, arrhythmia, myocyte toxicity
• Renal efferent arteriole vasoconstriction => decreased renal blood flow
• Increased adrenal aldosterone release =>increased distal tubular Na+ reabsorption, myocardial fibrosis
• Vascular smooth muscle contraction => increased cardiac afterload
• Vascular smooth muscle hypertrophy: decreased vascular compliance, atherosclerosis

Question 9

Hemodynamic Effects of Aldosterone in HF

Answer 9

• Retention of Na+ and water
• Increased plasma fluid volume
• Elevated BP

Question 10

Non-Hemodynamic Effects of Aldosterone in HF

Answer 10

• Myocardial and vascular fibrosis
• Impaired arterial compliance
• Baroreceptor dysfunction
• Sympathetic activation
• Excretion of K+ and Mg++
• Elevated ANP
• Parasympathetic inhibition

Question 11

SNS Activation in HF

Answer 11

• Increased HR: arrhythmias, impaired diastolic filling, increased myocardial energy demand
• Vasoconstriction: increased afterload
• Increased plasma renin activity: increased preload
• Direct toxic effects of NE: Apoptosis
• Desensitization to catecholamines
• Myocardial remodeling

Question 12

Vasopressin (AVP)

Answer 12

• Antidiuretic hormone (ADH)
• Regulates extracellular fluid volume by affecting renal handling of water
• AVP acts on renal collecting duct via V2 receptor to promote free water absorption
• Results in increased BV, CO, and arterial pressure
• AVP also acts on V1a receptors on vascular smooth muscle promoting vasoconstriction

Question 13

BNP

Answer 13

• One of four human natriuretic peptides (ANP, BNP, CNP, and DNP)
• Released from ventricles in response to ventricular stretching from volume overload
• Promotes diuresis, natriuresis, and vasodilation
• Metabolized by neutral endopeptidase
• Used diagnostically to rule out HF and potentially can be used to guide therapy