Chapter 20: Heart Failure and Circulatory Shock Porth

What are the five major complications of severe shock?

1. Pulmonary injury 2. Acute renal failure 3. Gastrointestinal ulceration 4. Disseminated intravascular coagulation 5. Multiple organ dysfunction syndrome

What type of heart failure does the condition of ischemic heart disease produce?

Diastolic dysfunction

The rise in preload seen in systolic dysfunction is thought to be a compensatory mechanism to help maintain stroke volume via the _____ mechanism despite a drop in ejection fraction.

Frank-Starling

____ has been defined as a complex syndrome that results from any functional or structural disorder of the heart that results in decreased pumping.

Heart failure

Orthopnea

Shortness of breath when supine

What is the primary physiologic result of obstructive shock?

The primary physiologic result of obstructive shock is elevated right heart pressure due to impaired right ventricular function.

What are the common manifestations of heart failure? Why?

The signs and symptoms include shortness of breath and other respiratory manifestations, fatigue and limited exercise tolerance, fluid retention and edema, cachexia and malnutrition, and cyanosis. Persons with severe heart failure may exhibit diaphoresis and tachycardia. These signs are the result of decreased tissue perfusion and resultant hypoxia.

What are the signs and symptoms of heart failure?

The signs and symptoms of heart failure include shortness of breath and other respiratory manifestations, fatigue and limited exercise tolerance, fluid retention and edema, cachexia and malnutrition, and cyanosis. Persons with severe heart failure may exhibit diaphoresis and tachycardia.

With both systolic and diastolic ventricular dysfunction, _____ are usually able to maintain adequate resting cardiac function until the later stages of heart failure.

compensatory mechanisms

As venous distention progresses in right-sided heart failure, blood backs up in the ____ veins that drain into the inferior vena cava, and the liver becomes engorged.

hepatic

Hypovolemic shock

Caused by a decrease in blood volume

Cardiogenic shock

Caused by alteration in cardiac function

Distributive shock

Caused by excessive vasodilation with normal distribution of blood flow

Obstructive shock

Caused by obstruction of blood flow through the circulatory system

What type of heart failure does the condition of valvular insufficiency produce?

Systolic dysfunction

How is cardiac contractility regulated?

A number of factors determine cardiac contractiliy by altering the systolic Calcium 2+ levels. Catecholamines increase Calcium 2+ entry into the cell by phosphorylation of the Calcium 2+ channels via a cAMP-dependent protein kinase. Another mechanism that can modulate inotropy is the sodium ion (Na+)/Calcium + exchange pump and the ATPase dependent Calcium 2+ pump on the myocardial cell membrane. These pumps transport Calcium 2+ out o the cell, thereby preventing the cell from becoming overloaded with Calcium 2+. If Calcium 2+ extrusion is inhibited, the rise in intracellular Calcium 2+ can increase inotropy.

What are the physiologic signs and symptoms of cardiogenic shock?

A, C, E. Signs and symptoms of cardiogenic shock include indications of hypoperfusion with hypotension, although a preshock state of hypoperfusion may occur with a normal blood pressure. The lips, nail beds, and skin may become cyanotic because of stagnation of blood flow and increased extraction of oxygen from the hemoglobin as it passes through the capillary bed. Mean arterial and systolic blood pressures decrease due to poor stroke volume, and there is a narrow pulse pressure and near-normal diastolic blood pressure due to arterial vasoconstriction. Urine output decreases due to lower renal perfusion pressures and the increased release of aldosterone. Elevation of preload is reflected in a rise in CVP and pulmonary capillary wedge pressure. Neurologic changes, such as alterations in cognition or consciousness, may occur due to low cardiac output and poor cerebral perfusion.

Cardiac reserve

Ability to increase cardiac output during increased activity

_____ is the most dramatic symptom of acute heart failure syndromes.

Acute pulmonary edema

Often, the early signs of heart failure are silent. This is because of the many compensatory mechanisms of the cardiovascular system. Explain, briefly, how these mechanisms work and why in the end they only serve to make the heart failure worse.

Adaptive responses: 1. Frank-Starling mechanisms: increases inotropy but eventually increases metabolic demand of cardiac tissue. 2. Activation of the sympathetic nervous system: increase inotropy, but increases wall tension and metabolic demand. 3. The renin-angiotensin-aldosterone mechanisms: increases blood volume and maintains cardiac output, but eventually increases wall tension. 4. Natriuretic peptides: inhibit sympathetic and renal compensation and decrease work of heart, but inactivation results in decreased cardiac output. 5. Myocardial hypertrophy and remodeling: cardiomyocyte hypertrophy and increased inotropy, but increase demands more oxygen and increases metabolic needs.

_____ is associated with impaired left ventricular filling that is due to changes in myocardial relaxation and compliance.

Aging

Cardiac output

Amount of blood the ventricles eject each minute

Circulatory shock

An acute failure of the circulatory system to supply the peripheral tissues and organs of the body with an adequate blood supply

Cyanosis

Bluish discoloration of the skin

Cardiac asthma

Bronchospasm due to congestion of the bronchial mucosa

____ can be expressed as the product of the heart rate and stroke volume.

Cardiac output

_____ can be described as an acute failure of the circulatory system to supply the peripheral tissues and organs of the body with an adequate blood supply, resulting in cellular hypoxia.

Circulatory Shock

Pulmonary congestion

Common sign of left ventricular failure

Inotropy

Contractile performance of the heart

When an acute event occurs and the circulatory system can no longer provide the body with adequate perfusion of its tissues and organs, cellular hypoxia occurs and the body goes into shock. What are the causes of shock in the human body?

Decrease in mean arterial pressures, increased urine output related to increased renal perfusion, hypercapnic lips and nail beds, increased extraction of oxygen from hemoglobin. Shock is a not a specific disease but a syndrome that can occur in the course of many life-threatening traumatic conditions or disease states. It can be caused by an alteration in cardiac function (cardiogenic shock), a decrease in blood volume (hypovolemic shock), excessive vasodilation with maldistribution of blood flow (distributive shock), or obstruction of blood flow through the circulatory system (obstructive shock).

What effect does diuretic therapy have on heart failure?

Diuretics promote the excretion of fluid and help to sustain cardiac output and tissue perfusion by reducing preload and allowing the heart to operate at a more optimal part of the Frank-Starling curve.

____ is the percentage of blood pumped out of the ventricles with each contraction.

Ejection fraction

Systolic dysfunction

Ejection fraction less than 40%

High-output failure

Failure that is caused by an excessive need for cardiac output

Neurogenic shock, or spinal shock, is a phenomenon caused by the inability of the vasomotor center in the brain stem to control blood vessel tone through the sympathetic outflow to the blood vessels. In neurogenic shock, what happens to the heart rate and the skin?

Heart rate slower than normal; skin warm and dry. In contrast, to other shock states due to the loss of blood volume or impaired cardiac function, the heart rate in neurogenic shock often is slower than normal, and the skin is dry and warm. This type of distributive shock is rare and usually transitory.

What type of heart failure does the condition of Paget disease produce?

High-output failure

_____ is an uncommon type of heart failure that is caused by an excessive need for cardiac output.

High-output failure

Circulatory failure

Hypoperfusion of organs and tissues

_____ shock is characterized by diminished blood volume such that there is inadequate filling of the vascular compartment.

Hypovolemia

What are the cellular consequences of shock?

In severe shock, cellular metabolic processes are essentially anaerobic because of the decreased availability of oxygen. Excess amounts of lactic acid accumulate in the cellular and extracellular compartment, and limited amounts of ATP are produced and normal cell function cannot be maintained. The sodium-potassium membrane pump is impaired, resulting in cellular edema and an increase in the permeability of cell membranes. Mitochondrial activity becomes severely depressed and lysosomal membranes may rupture, resulting in the release of enzymes that cause further intracellular destruction. This is followed by cell death and the release of intracellular contents into the extracellular spaces. The destruction of the cell membrane activates the arachidonic acid cascade, release of inflammatory mediators, and production of oxygen free radicals that extend cellular damage.

_____ is caused by disorders that impair the pumping ability of the heart, such as ischemic heart disease and cardiomyopathy.

Low-output failure

Dyspnea

Labored breathing

Anaphylactic shock is the most severe form of systemic allergic reaction. Immunologically medicated substances are released into the blood, causing vasodilation and an increase in capillary permeability. What physiologic response often accompany the vascular response in anaphylaxis?

Laryngeal edema. Anaphylaxis is a clinical syndrome that represents the most severe form of systemic allergic reaction. Anaphylactic shock results from an immunologically mediated reaction in which vasodilator substances such as histamines are released into the blood. The vascular response in anaphylaxis is often accompanied by life-threatening laryngeal edema and bronchospasm, circulatory collapse, contraction of gastrointestinal and uterine smooth muscle, and urticaria (hives) or angioedema.

What type of heart failure does the condition of acute myocardial infarction produce?

Left ventricular dysfunction

_____ is the most common cause of right ventricular failure.

Left ventricular failure

What type of heart failure does the condition of cardiomyopathy produce?

Low-output failure

The pathogenesis of multiorgan dysfunction syndrome (MODS) is not clear understood at this time. Supportive management is currently the focus of treatment in this disorder. What is not a major risk factor in MODS? a. Advanced age b. Alcohol abuse c. Respiratory dysfunction d. Infarcted bowel

Major risk factors for the development of MODS are severe trauma, sepsis, prolonged periods of hypotension, hepatic dysfunction, infarcted bowel, advanced age, and alcohol abuse. Respiratory dysfunction is not a major risk factor in MODS.

____ dyspnea is a sudden attack of dyspnea that occurs during sleep.

Paroxysmal nocturnal

Cheyne-Stokes respiration

Periodic breathing characterized by gradual increase in depth followed by a decrease resulting in apnea

Endothelins

Potent vasoconstrictors

Sepsis is growing in incidence in the United States. Its pathogenesis includes neturophil activation, which kills microorganisms. Neutrophils also injure the endothelium, releasing mediators that increase vascular permeability. What else to neutrophils do in sepsis?

Releases nitric oxide. Although activated neutrophils kill microorganisms, they also injure the endothelium by releasing mediators that increase vascular permeability. In addition, activated endothelial cells release nitric oxide, a potent vasodilator that acts as a key mediator of septic shock.

Cor pulmonale

Right heart failure occurs in response to chronic pulmonary disease

What type of heart failure does the condition of aoritc or mitral stenosis produce?

Right ventricular dysfunction

_____ heart defects are the most common cause of heart failure in children.

Structural

What is the primary cause of heart failure in infants and children?

Structural (congenital) heart defects are the most common cause of heart failure in children.

An important factor in the mortality of severe shock is acute renal failure. What is the degree of renal damage related to in shock?

The degree of renal damage in shock is related to the severity and duration of shock.

Afterload

The force that the contracting heart muscle must generate to eject blood from the filled heart

Ascites

Transudation of fluid into the peritoneal cavity

Hydrothorax

Transudation of fluid into the pleural caviity

In hypovolemic shock the main purpose of treatment is correcting or controlling the underlying cause of the hypovolemia and improving the perfusion of the tissues and organs of the body. Which of the following treatments is NOT a primary form of therapy for hypovolemic shock? a. Surgery b. Administration of intravenous fluids and blood. c. Vasoconstrictive drugs d. Infusion of blood and blood products.

Vasoconstrictive drugs. The treatment of hypovolemic shock is directed toward correcting or controlling the underlying cause and improving tissue perfusion. Ongoing loss of blood must be corrected, such as in surgery. Oxygen is administered to increase oxygen delivery to the tissues. Medications usually are administered intravenously. In hypovolemic shock, the goal of treatment is to restore vascular volume. This can be accomplished through intravenous administration of fluids and blood. The crystalloids (e.g. isotonic saline and Ringer's lactate) are readily available and effective, at least temporarily. Plasma volume expanders (e.g. pentastarch and colloidal albumin) have a high molecular weight, do not necessitate blood typing, and remain in the vascular space for longer periods than crystalloids, such as dextrose and saline. Blood or blood products (packed or frozen red blood cells) are administered based on hematocrit and hemodynamic findings. Fluids and blood are best administered based on volume indicators such as CVP and urine output. Vasoactive medications are agents capable of constricting or dilating blood vessels. Considerable controversy exits about the advantages or disadvantages related to the use of these drugs. As a general rule, vasoconstrictor agents are not used as a primary form of therapy in hypovolemic shock and may be detrimental. These agents are only given when volume deficits have been corrected but hypotension persists.

_____ shock is characterized by loss of blood vessel tone, enlargement of the vascular compartment, and displacement of the vascular volume away from the heart and central circulation.

Vasoldilatory

Preload

Volume or loading conditions of the ventricle at the end of diastole

Why is it advisable to test cardiac function during exercise (stress) rather than at rest?

With both systolic and diastolic ventricular dysfunction, compensatory mechanisms are usually able to maintain adequate resting cardiac function until the later stages of heart failure. Therefore, cardiac function measured at rest is a poor clinical indicator of the extent of cardiac impairment because cardiac output may be relatively normal at rest.

How does diastolic dysfunction produce the typical signs and symptoms that characterize the condition?

With diastolic dysfunction, blood is unable to move freely into the left ventricle, causing an increase in intraventricular pressure at any given volume. The elevated pressures are transferred backward from the left ventricle into the atria and pulmonary venous system causing a decrease in lung compliance, which increases the work of breathing and evokes symptoms of dyspnea. Cardiac output is decreased because of a decrease in the volume (preload) available for adequate cardiac output. Inadequate cardiac output during exercise may lead to fatigue of the legs and the accessory muscles of respiration.

A gradual or rapid change in heart failure signs and symptoms resulting in a need for urgent therapy is defined as _____ syndrome.

acute heart failure

In acute or severe left-sided failure, cardiac output may fall to levels that are insufficient for providing the ____ with adequate oxygen.

brain

Measurements of ______ are recommended to confirm the diagnosis of heart failure to evaluate the severity of left ventricular compromise and estimate the prognosis, and predict future cardiac events such as sudden death, and to evaluate the effectiveness of treatment.

brain natriuretic peptide (BNP)

Among the conditions that cause diastolic dysfunction are those that ______ the ventricle (e.g. pericardial effusion, constrictive pericarditis), those that ____ wall thickness and reduce chamber size (e.g. myocardial hypertrophy, hypertrophic cardiomyopathy), and those that ____ diastolic relaxation (e.g. aging, ischemic heart disease).

compress, increase, delay

Systolic dysfunction commonly results from conditions that impair the ____ performance of the heart (e.g. ischemic heart disease and cardiomyopathy), produce a ______ (e.g. valvular insufficiency and anemia), or generate a _____ (e.g. hypertension and valvular stenosis) on the heart.

contractile, volume overload, pressure overload

Among the most common causes of heart failure are _____, ______, dilated cardiomyopathy, and ____ heart disease.

coronary artery disease, hypertension, valvular

In systolic ventricular dysfunction, myocardial contracility is impaired, leading to a _____ in the ejection fraction and cardiac output.

decrease

In _____ dysfunction, cardiac output is compromised by the abnormal filling of the ventricle.

diastolic

Anaphylactic shock results from an _____ mediated reaction in which vasodilator substances such as histamine are released into the blood.

immunologically

Endurance athletes have ____ cardiac reserves.

large

The most common causes of _____ ventricular dysfunction are acute myocardial infarction and cardiomyopathy.

left

Beta-adrenergic receptor blocking drugs are used to decrease _____ dysfunction associated with activation of the sympathetic nervous system.

left ventricular

The development of _____ constitutes one of the principle mechanisms by which the heart compensates for an increase in workload.

myocardial hypertrophy

The most common cause of cardiogenic shock is _____.

myocardial infarction

A defect in the vasomotor center in the brain stem or the sympathetic outflow to the blood vessels is known as ______.

neurogenic shock

Diastolic ventricular dysfunction is characterized by a _____ ejection fraction but impaired diastolic ventricular relaxation leading to a decrease in ventricular filling, which ultimately causes a decrease in preload, stroke volume, and cardiac output.

normal

Central cyanosis is caused by conditions that impair _____ of the arterial blood.

oxygenation

A major effect of right-sided heart failure is the development of ______.

peripheral edema

Ascites is a common manifestation associated with _____ ventricular failure and long-standing elevation of systemic venous pressures.

right

Heart failure can be classified according to the _____ of the heart that is primarily affected.

side

The _____ is a function of preload, afterload, and myocardial contractility.

stroke volume

The heart rate is regulated by a balance between the activity of the _____ nervous system, which produces an increase in heart rate, and the ____ nervous system, which slows it down.

sympathetic, parasympathetic

Diastolic dysfunction can be aggravated by _____ and can be improved by a reduction in heart rate.

tachycardia

In persons with ventricular dysfunction, sudden death is caused most commonly by ____ tachycardia or fibrillation.

ventricular