Chapter 20 Heart Failure and Circulatory Shock Essentials of Pathophysiology Chapter 20 Heart Failure and Circulatory Shock

Pre Lecture Quiz True/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 Ventricular Contraction initiated Ventricular Relaxation Atrial Contraction initiated Papillary 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

High-output versus low-output failure Systolic or diastolic failure 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 Author: Please add title.

Control of Heart function Author: Please add title.

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 Blood Flow body Systolic: LV does not pump enough blood to body Body lacks blood right left heart heart Lungs fill with fluid Diastolic: LV does not accept enough blood from lungs lungs

Right-Sided Heart Failure Blood Flow Diastolic: RV does not accept enough blood from body body Body fills with blood right left heart heart Lungs do not oxygenate enough blood Systolic: RV does not pump enough blood to lungs lungs

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.

Heart fails to pump blood adequately 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

BP = CO x PR Blood Pressure 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? Cardiogenic Hypovolemic Distributive Septic

Answer 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 Allergen Mechanism of Type I Hypersensitivity Granules released: Histamine, acetylcholine, kinins, leukotrienes, and prostaglandins all cause vasodilation IgE attaches to mast cell Allergen attaches to IgE Mast cell degranulates

Anaphylaxis Systemic response to the inflammatory mediators released in type I hypersensitivity Histamine, acetylcholine, kinins, leukotrienes, and prostaglandins all cause vasodilation What will happen when arterioles vasodilate throughout the body? Acetylcholine, kinins, leukotrienes, and prostaglandins all can cause bronchoconstriction 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 Author: Please add title.

Gut Barrier Failure decreased perfusion of the gut bacterial bacteria and bacterial toxins escape endotoxins in blood and lymph inflammatory response inflammatory mediators in blood vasodilation and lymph

Septic Shock vasodilation decreased peripheral resistance decreased blood pressure SEPTIC SHOCK 40% mortality

The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome 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 inflammatory mediators vascular endothelial cells respond and: promote create produce more clot adhesive vasodilation formation molecules substances (NO) more WBCs move out into more the tissues and release more vasodilation inflammatory mediators (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)

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.” (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)

Septic Shock (cont.) “Third, administration of anti-endotoxin antibodies in large, clinical trials did not improve survival.” (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)

Question Which type of shock is the result of a severe allergic reaction? Cardiogenic Obstructive Anaphylactic Septic

Answer 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.

The main function of protein C is its anticoagulant property as an inhibitor of coagulation factors V and VIII 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!

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) pathways activated clots in platelets many and small clotting blood proteins vessels used up microinfarcts, bleeding ischemia 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 True Because 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.