CHAPTER 20 HEART FAILURE AND CIRCULATORY SHOCK Essentials of Pathophysiology.

CHAPTER 20

HEART FAILURE AND CIRCULATORY SHOCK

CHAPTER 20

HEART FAILURE AND CIRCULATORY SHOCK

Essentials of Pathophysiology

PRE LECTURE QUIZTrue/False Decreased cardiac output will lead to an increase in

renal blood flow and glomerular filtration rate. The endothelins are potent vasodilators that are

released from the endothelial cells throughout the circulation.

Myocardial hypertrophy is a long-term mechanism by which the heart compensates for increased workload.

Afterload represents the force that the contracting heart must generate to eject blood from the filled heart.

Five major complications of severe shock are acute respiratory distress syndrome, acute renal failure, gastrointestinal ulceration, disseminated intravascular coagulation, and multiple organ dysfunction syndrome.

F

F

T

T

T

PRE LECTURE QUIZ In __________ heart failure, blood backs up in the

systemic circulation, causing peripheral edema and congestion of the abdominal organs.

The most common cause of ____________ shock is myocardial infarction.

Examples of conditions that cause __________ shock include loss of whole blood (e.g., hemorrhage), plasma loss (e.g., severe burns), or extracellular fluid (e.g., gastrointestinal fluids lost in vomiting or diarrhea).

An increase in __________ rate is an early sign of shock.

A life-threatening condition, acute __________ edema is the most dramatic symptom of left heart failure and is characterized by capillary fluid moving into the alveoli.

cardiogenic

heart

hypovolemic

pulmonary

right

STANDARD ECG WAVEFORM

Atrial Contraction initiated

Ventricular Contraction initiated Ventricular

RelaxationPapillary Muscle

Relaxation

ST segment can indicate ischemia or infarction

ST SEGMENT ELEVATION

ST Depression

With a 12 lead ECG certain leads can be connected to each other to reverse the R wave and accentuate the ST Elevation

CORORNARY OCCLUSION

total occlusion of the proximal segment of left

anterior descending artery, and

severe disease involving the proximal segment of

the obtuse marginal branch

Angiogram

TYPES OF HEART FAILURE

High-output versus low-output failure Is cardiac output high or low?

Systolic or diastolic failure Is the heart failing to pump out enough

blood, or failing to accept enough blood from the body and lungs?

Right-sided or left-sided failure Is the right or left side of the heart

failing?

MANIFESTATIONS OF HEART FAILURE

Effects of impaired pumping

Effects of decreased renal blood flow RAA pathway

Effects of the sympathetic nervous system

Angioplasty CABG

MANIFESTATIONS OF HEART FAILURE

Orthopnea: Straight Breathing, ie. Must be

straight upright, or difficult breathing occurs

CONTROL OF HEART FUNCTION

SCENARIO:

Mr. M has heart failure and he complains of severe shortness of breath, and has fluid in his lungs. He has tachycardia, increased diastolic blood pressure, pale moist skin, and says he feels weak, dizzy, and anxious all the time.

Question:Which of these signs and symptoms are due to decreased renal blood flow?

Which are due to the sympathetic nervous system? Which side of his heart do you think is failing?

LEFT-SIDED HEART FAILURE

Systolic: LV does not pump enough blood to body

Diastolic: LV does not accept enough blood from lungs

Body lacks blood

Lungs fill with fluid

right heart

lungs

left heart

body

Blood Flow

RIGHT-SIDED HEART FAILURE

Systolic: RV does not pump enough blood to lungs

Diastolic: RV does not accept enough blood from body

Body fills with blood

Lungs do not oxygenate enough blood

right heart

lungs

left heart

body

Blood Flow

PULMONARY EDEMA

Capillary fluid moves into alveoli Lung becomes stiffer Harder to inhale Less gas exchange in alveoli Crackles Frothy pink sputum

Hemoglobin not completely oxygenated

QUESTION

Tell whether the following statement is true or false:

The characteristic pink sputum produced is pulmonary edema is tinged with blood.

ANSWER

True

In pulmonary edema, the alveolar capillary membrane is damaged, and blood from the capillaries moves into the alveoli. The blood from the capillaries causes the sputum (produced from the lower respiratory tract) to appear pink or light red.

CARDIOGENIC SHOCK

Heart fails to pump blood adequately

Decreased cardiac output lowers BP

Sympathetic system responds

Vasoconstriction increases resistance to blood flow

Increased workload on heart worsens heart failure

TYPES OF SHOCK

Cardiogenic

Hypovolemic

Obstructive

Distributive

Septic

BLOOD PRESSURE

BP = CO x PR

Which of the following affect CO, and which affect PR? Why? Blood volume Heart rate Vasoconstriction Angiotensin II Aldosterone Epinephrine Histamine

SCENARIO:

Mr. M was injured in a motorcycle accident.

On his arrival at the hospital he presented with bleeding from the right leg, restlessness, pallor, sweating, elevated heart rate, weak pulse, rapid breathing, and lack of bowel sounds; his blood pressure was slightly elevated

Question: What has happened to this patient’s:

Stroke volume Cardiac output Sympathetic nervous system

SCENARIO (CONT.)

Although he was given 6 units of blood, Mr. M got worse

He became lethargic and his blood pressure began to fall; he still had no bowel sounds or urine production

Question: The intern ordered epinephrine, and

Mr. M’s blood pressure increased. Why?

Later, you overhear the resident telling the intern that was not the best treatment. Why not, if it raised Mr. M’s blood pressure?

SCENARIO (CONT.)

Mr. M’s blood pressure went up a bit

He has been moved out of the ICU

Question:

His chart says you should do a 24-hour urine collection. Why?

SCENARIO (CONT.)

Mr. M appears to be improving

He sleeps quite a lot, but his blood pressure has remained stable; he had a little urine production; and he did not eat his supper

Checking on him in the evening, you notice that he is slightly flushed, his respiration rate is a little high, and his temperature is elevated

Question:

What is happening to his peripheral resistance?

What do you expect his heart rate to be like? Why?

DISTRIBUTIVE OR VASODILATORY SHOCK

Blood vessels dilate

There is not enough blood to fill the circulatory system

Blood flow decreases

Less blood is returned to the heart

Less blood is circulated to the body

QUESTION

Which type of shock is caused by low blood volume?

a. Cardiogenic

b. Hypovolemic

c. Distributive

d. Septic

ANSWER

b. Hypovolemic

Hypo (low) volemia (blood volume) occurs when a patient has lost blood due to trauma, surgery, or third space fluid loss.

CAUSES OF DISTRIBUTIVE SHOCK

Decreased sympathetic activity: neurogenic Brain or spine injury; anesthetics;

insulin shock; emotion Vasodilator substances in blood

Type I hypersensitivity (anaphylactic shock)

Inflammatory response to infection (sepsis)

Vessel damage from severe hypovolemia

MECHANISM OF TYPE I HYPERSENSITIVITY

Mast cell

Mast cell degranulates

IgE attaches to mast cell

Allergen attaches to IgE

Allergen

Granules released: Histamine,

acetylcholine, kinins, leukotrienes, and prostaglandins all cause vasodilation

ANAPHYLAXIS

Systemic response to the inflammatory mediators released in type I hypersensitivity

Histamine, acetylcholine, kinins, leukotrienes, and prostaglandins all cause vasodilation

º What will happen when arterioles vasodilate throughout the body?

Acetylcholine, kinins, leukotrienes, and prostaglandins all can cause bronchoconstriction

º What will happen when the bronchioles constrict?

SEPSIS OR SYSTEMIC INFLAMMATORY RESPONSE SYNDROME (SIRS)

Inflammatory mediators released into the circulation Tumor necrosis factor Interleukins Prostaglandins

Cause systemic signs of inflammation Fever and increased respiration,

respiratory alkalosis, vasodilation, warm flushed skin

Activate inflammatory pathways Coagulation, complement

SEPSIS OR SYSTEMIC INFLAMMATORY RESPONSE SYNDROME (SIRS) (CONT.)

Discussion:

Why is septic shock called distributive?

In the later phases of septic shock, blood volume decreases. What part of the inflammatory process explains this?

TYPES OF SHOCK

GUT BARRIER FAILUREdecreased perfusion of the gut

bacteria and toxins escape

inflammatory response

bacterial endotoxins

in blood and lymph

inflammatory mediators in blood

and lymphvasodilation

SEPTIC SHOCK

vasodilation

decreased peripheral resistance

decreased blood pressure

SEPTIC SHOCK40% mortality

SEPTIC SHOCK Also called systemic

inflammatory response syndrome (SIRS)

Inflammatory mediators also increase the metabolic rate of tissues, so they need more oxygen

The role of the endothelium in severe sepsis and multiple organ

dysfunction syndrome

(Aird, W. C. [2003.] The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome. Blood 101[10],3765-3777. Retrieved February 10, 2004, from http://www.blood journal.org/cgi/content/full/101/10/3765.0)

inflammatory mediators

vascular endothelial cells respond and:

promote clot

formation

create adhesive molecules

more WBCs move out into the tissues and release more

inflammatory mediators

produce more vasodilation

substances (NO)

more vasodilation

The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome

SEPTIC SHOCK (CONT.)

“Despite the prompt implementation of appropriate antibiotic therapy, sepsis mortality remains high, in the range of 28% to 50%.”


“Second, patients with culture-positive and culture-negative sepsis or septic shock have comparable mortality rates.”

SEPTIC SHOCK (CONT.)

“Third, administration of anti-endotoxin antibodies in large, clinical trials did not improve survival.”


QUESTION

Which type of shock is the result of a severe allergic reaction?

a. Cardiogenic

b. Obstructive

c. Anaphylactic

d. Septic

ANSWER

c. Anaphylactic

Anaphylactic shock is caused when inflammatory mediators are released (type I hypersensitivity reaction). The mediators include histamine, acetylcholine, kinins, leukotrienes, and prostaglandins, all of which cause vasodilation.

ACTIVATED PROTEIN C

Drotrecogin alpha - a recombinant form of human activated protein C that has anti-thrombotic, anti-inflammatory, and profibrinolytic properties - a treatment for severe sepsis

Blocks clotting

Blocks inflammation

Increases survival of the most seriously ill sepsis patients

May cause bleeding!

The main function of protein C is its anticoagulant property as an inhibitor

of coagulation factors V and VIII

COMPLICATIONS OF SHOCK

Scenario: A doctor has been called in to treat Mr. M

and has started him on fluid and antibiotics

You are warned to watch him carefully for any signs of respiratory distress

Question: Why would blood pressure

imbalances cause respiratory distress?

COMPLICATIONS OF SHOCK (CONT.)

Acute respiratory distress syndrome

Acute renal failure

Gastrointestinal complications

Disseminated intravascular coagulation

Multiple organ dysfunction syndrome

ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)

Exudate enters alveoli Blocks gas exchange Makes inhaling more difficult

Neutrophils enter alveoli Release inflammatory

mediators Release proteolytic enzymes

ACUTE RENAL FAILURE (ARF)

Renal vasoconstriction cuts off urine production Acute renal failure

Continued vasoconstriction cuts off renal oxygen supply

Renal tubular cells die Acute tubular necrosis

DISSEMINATED INTRAVASCULAR COAGULATION (DIC) coagulation

pathways activated

clots in many small blood vessels

microinfarcts, ischemia

platelets and

clotting proteins used up

bleeding problems

MULTIPLE ORGAN DYSFUNCTION SYNDROME (MODS)

The most frequent cause of death in the noncoronary intensive care unit

Mortality rates vary from 30% to 100%

Mechanism not known

QUESTION

Tell whether the following statement is true or false:

Treatment for ARDS often includes breathing assistance using mechanical ventilation.

ANSWER

TrueBecause alveoli are filled with exudate

and blood that has leaked from the capillary, the surface area available for gas exchange is greatly reduced. Most patients will require ventilatory support until the process reverses. ARDS has a high mortality rate because it is difficult to ventilate these patients.

CHAPTER 20 HEART FAILURE AND CIRCULATORY SHOCK Essentials of Pathophysiology.

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