Pathophysiology 1 - Chapter 19

What defines heart failure?

Inability of heart to maintain sufficient cardiac output to meet metabolic demands of tissues and organs

Heart failure (HF) is a potential consequence of

Most cardiac disorders

True or False: Mortality for HF is high, 50% of patients die within 5 years of diagnosis

True

Most common cause of HF?

• myocardial ischemia (CHD) followed by

• hypertension

• dilated cardiomyopathy

What does HF result from?

Impaired ability of myocardial fibers to contract, relax, or both

Symptoms of fluid overload sometimes are described as

congestive heart failure in HF patients

When it comes to Systolic Dysfunction with low ejection fraction, what is reduced contractility evidenced by?

low ejection fraction (EF) and reduced muscular contraction during ventricular systole

What is a common etiology of Systolic Dysfunction with low ejection fraction?

Myocardial infarction

What are less common causes of Systolic Dysfunction with low ejection fraction?

heart defects, valve disorders, respiratory diseases, anemia

Diastolic Dysfunction with preserved Ejection Fraction is a disorder of

Myocardial relaxation

• Left ventricle is excessively noncompliant and does not fill effectively

What is the hallmark of diastolic dysfunction with preserved ejection fraction?

Patients exhibits low cardiac output, congestion, and edema formation with normal ejection fraction

What is increased preload defined as?

A compensatory mechanism that enhances the ability of the myocardium to contract more forcefully.

Current management of HF directed toward reducing the harmful consequences of these compensatory responses:

• increased heart rate and contractility (though SNS activation)

• increased preload

• myocardial hypertrophy

HF impacts afterload on which ventricle?

the left ventricle - it increases

Clinical presentation depends on which ventricle (left or right or both)

is failing to pump blood adequately

Forward effects of HF

inadequate ability to push the blood forward by the pumping ventricle (cardiac output)

Backwards effects of HF

Congestion of blood behind the pumping ventricle

Left-sided HF causes what type of edema?

pulmonary edema

Right-sided HF causes what type of edema?

systemic edema

Biventricular HF causes what type of edema?

pulmonary and systemic edema

Left HF is most often associated with

Left ventricular infarction

Right HF is associated with

Right ventricular infarction

True or False: Biventricular heart failure is most often the result of primary left ventricular failure that has progressed to right sided heart HF

True

Describe biventricular HF

• cardiac output is reduced

• pulmonary congestion (due to LHF)

• systemic venous congestion (due to RHF)

True or False: Beta blockers inhibit SNS effects

True

What are dysrhythmias significant for?

• For indicating an underlying pathophysiologic disorder

• For impairing normal cardiac output

What are factors that cause dysrhythmia?

Hypoxia, electrolyte imbalance, trauma, inflammation, and drugs

What are dysrhythmias?

Also called arrhythmias, abnormality of the cardiac rhythm of impulse generation or conduction

Three major types of dysrhythmias

• abnormal rates of sinus rhythm

• electrical impulse generation from abnormal sites (ectopic)

• disturbances in conduction pathways

Describe normal sinus rhythm

• Starts in the SA node and follows the normal pathway

• P wave precedes every QRS complex

• PR, QRS, QT intervals are of normal duration

Impulse from the SA node goes through the atria, AV node, His/Purkinje system, and ventricular myocardium depolarizes or repolarizes?

Depolarizes

Electrical depolarization of the heart leads to

atrial and then ventricular muscle contraction

Tachycardia

Fast heart rate

Bradycardia

Slow heart rate

Sinus arrythmia

a degree of variability in the heart rate

Sinus arrest

Flat trace for a period of few seconds (dead tbh)

True or False: Escape rhythms are associated with low cardiac output

True

Describe escape rhythms

• heart misses beats

• originates in AV node

• poorly tolerated

• no P wave

Junctional escape rhythm rate

59/min

Ventricular escape rhythm rate

33/min

Atrial flutter

• Atrial rate of 240/350 beats/min

• Ventricular rate may be regular or irregular

• Patients usually have underlying heart disease

Atrial fibrillation

• completely disorganized and irregular atrial rhythm

• allows blood to become stagnant in the atria and may lead to formation of thrombi

• patients are given anticoagulant drugs

Ventricular tachycardia

• often associated with myocardial ischemia

• rapid rate (>100 beats/min)

• loss of consciousness

• death if not managed quickly

Ventricular fibrillation

• rapid uncoordinated ventricular quivering

• loss of consciousness

• death if not managed quickly