Life Support: Lecture 3:

Coronary Heart Disease

Chronic condition of plaque buildup (atherosclerosis) in the heart arteries

There is also acute coronary heart disease which is sudden acute events (like heart attack) caused by plaque rupturing or blocking blood flow

Atherosclerosis:

Cholesterol building up in the arteries forming plaque

• This causes the arteries to narrow and have reduced blood flow

Risk Factors for Coronary Heart Disease

Family History and Unhealthy Lifestyle (Bad diet and exercise which lead to high cholesterol)

Stable Angina:

Early Stage of CHD and it is caused by partially narrowed arteries

• In exercise narrow arteries don’t get enough blood to the heart muscle which leads to ischemia and is represented as chest pain

Ischemia

a critical condition where restricted blood flow to a tissue or organ causes a severe shortage of oxygen and nutrients (in this case heart muscle)

Unstable Angina

More severe than stable angina, now chest pain also occurs at rest due to narrower arteries and indicates that a heart attack may occur

Acute Myocardial Infarction:

Heart attack in which the coronary artery is blocked. If it becomes blocked no blood is ale to flow to the heart muscle (myocardium) (blood clot or plaque buildup)

How to Diagnose?

Chest Pain and Radiation of Pain to Left Arm and Jaw, Sweating, Nausea and Vomiting

Risk Factors of CHD:

Smoking, High BP (hypertension), High Cholesterol (hypercholesterolemia), diabetes, obesity, family history, CVD and pervious stable angina

Why do these factors cause for a risk of CHD?

These factors damage blood vessels which promotes atherosclerosis, or pre-existing coronary artery narrowing

Electrocardiogram:

Measures electrical activity of the heart using P, QRS and T waves. Electrodes (leads) are placed on the patient and reflects how electrical impulses travel through the heart

Troponin Test:

Assesses if there is troponin in the bloodstream. This is helpful as troponin is only released when the heart is damaged, and therefore this blood test can show if someone is having a silent heart attack (ECG would not detect this)

Ischemia and Infarction on ECG

Ischemia: Shows T wave inversion and ST depression

Treatment of CHD:

• Stent Placement: Adding a stent into the artery to open a narrowed or blocked artery (minimally invasive)

• Coronary Artery Bypass Grafting: Surgical procedure in which an artery of the legs or chest is used to create a new pathway for blood to reach the heart muscle

• Better Lifestyle and Medication

Aortic Dissection:

The aorta has a tear in one of its three layers (intima) and blood enters the vessel wall which creates a false lumen (extra channel that shouldn’t exist)

• This weakens the vessel and creates the risk of a rupture, this is dangerous as the aorta is a high pressure vessel and a rupture would cause massive internal bleeding reducing blood flow to organs

Type A Aortic Dissection:

Tear in the ascending aorta

• Type I: ascending and descending aorta

• Type II: only ascending aorta

Type A Aortic Dissection Treatment:

Immediate surgery is required, the part that is ruptured must be removed and replaces with a bypass tube

Type B Aortic Dissection:

Tear in the descending aorta

• A tear leads to impaired blood flow to the kidney, intestines and lower body

Treatment for Type B Aortic Dissection:

First blood pressure control and rest

Surgery only if complications occur

How to Diagnose Aortic Dissection?

• Acute severe pain in shoulder blades, chest or abdomen, Typical patient: man aged 60-70 years old

• Can cause shock

• Can be seen on a CT scan or echo

Atrial Fibrillation:

Multiple foci in the artia rapidly fire, therefore there is no sign pacemaker (SA Node) and atria does not contract properly it only fibrillates

The Effect of Atrial Fibrillation on Ventricles

The ventricles receive irregular signals as well and therefore leads to an irregular rhythm

• The ventricles do not fill properly with blood due to the irregular and fast rhythm and no effective atrial contractions occur

• ↓ Ventricular filling, ↓ Cardiac output, ↓ Blood flow to brain

How is Atrial Fibrillation represented on a ECG?

No regular P waves, and irregular signals lead to irregular rhythm on the ECG (tachycardia)

Symptoms of Atrial Fibrillation:

• Dizziness, Collapsing, Tachycardia (leads to cardiac fatigue and heart failure → tachcardia-induced cardiomyopathy) and Palpitations

• High BP (hypertension)

Treatment for Atrial Fibrillations:

• Anticoagulants: In AF blood clots start to form due to blood pooling from irregular heartbeats and it also increases the risk of a stroke, Anticoagulants are used to prevent blood clots from forming and a stroke occurring

• Medication: Rate/Rhythm control to lower the heart rate allowing for ventricular filling

• Cardioversion: Electrical and Chemical

  • Electrical: two pads placed on chest and a shock is delivered to reset the heart to SA Node

  • Chemical: Use of antiarrhythmic drugs to convert rhythm back to sinus rhythm

• Ablation: Insert a catheter into the heart and burn the spots that are signalling incorrectly so it goes back to sinus rhythm

Cardiac Tamponade

Drastic drop in BP due to blood, fluid or pus filling up the pericardial sac surrounding the heart preventing it from filling properly

Science behind Cardiac Temponade:

After there is trauma to the heart, the pericardial sac fills up leading to the narrowing of the ventricles (and heart chambers)

• This means that the heart cannot fill up properly in diastole leading to the blood being backed up into the veins (shown as bulging neck veins) (↓ Filling → ↓ stroke volume → ↓ cardiac output)

• Since there is less blood pumped it leads to hypotension

Symptoms of Cardiac Temponade:

• hypotension which causes tachycardia, leads to shock, respiratory distress

• Occurs due to trauma in heart (stabing)

• Muffles Heart Sounds in Stethoscope, Hypotension, Bulging Neck Veins

How to measure Cardiac Temponade:

Cardiac Ultrasound, X-ray on chest, ECG and CT-scan

Treatment of Cardiac Temponade:

• Pericardiocentesis: An ultrasound-guided needle insertion used to remove fluid/blood from the pericardial sac to relieve pressure

• Resuscitative Thoracotomy: Opening the chest wall to gain access to the heart to control bleeding and relieve temponade

Heart Failure (Decompensatio Cordis)

Failure of the pump function of the heart leading to pulmonary edema

Pulmonary Edema:

condition characterized by excess fluid buildup in the lung's air sacs (alveoli), causing severe breathing difficulty and potential respiratory failure

Astma Cardiale:

severe breathing difficulty and potential respiratory failure

Causes of Heart Failure:

heart attack, hypertension, valve abnormalities, medication (chemotherapy), anemia and infection of the heart

Anemia:

occurs when your body lacks enough healthy red blood cells or hemoglobin to carry adequate oxygen to its tissues

Symptoms of Heart Failure:

Weight gain due to fluid retention and shortness of breath (usually at night when you lie down) due to the fluids, and fatigue, high BP (hypertension) and high respiratory rate (tachypnea)

How can you test for Heart Failure:

Blood test, and X-ray of the chest

• Normal lungs: dark (air-filled)

• Edema: white (fluid-filled)

Treatment for Heart Failure:

• Oxygen Therapy: High pressure in the hope that fluid is removed from lungs back into circulation, then eliminated via kidneys

• Continuous Positive Airway Pressure (CPAP): Applies positive pressure, helps to keep alveoli open and push fluid out of alveoli back into circulation

• Medication: Nitroglycerin and Diuretics:

  • Nitroglycerin: Opens blood vessels which reduces BP and fluid leakage (leads to vasodilation)

  • Diuretics: Removes excess fluids from the body, so blood volume decreases and therefore pressure which reduces pulmonary edema

..

..

Shock:

a reduction in systemic perfusion causing inadequate tissue oxygen delivery to meet demand, resulting in anaerobic metabolism and the formation of lactic acid

Tissue Hypoxia:

tissues receive inadequate oxygen, preventing proper cellular respiration and ATP production

• In shock this lactate accumulation is pathological due to tissue hypoxia

Reversible vs Irreversible Lactate Production

• In the beginning phase it is reversible, but can rapidly turn irreversible and turn into organ damage/dysfunction, cell death and death

• During physical exercise you also produce lactate but this is physiological and can therefore be reversed (not pathological)

What is oxygen delivery dependant on

Cardiac Output x Hemoglobin x Oxygen Saturation

• Cardiac Output: Stroke Volume x Heart Rate

• Hemoglobin: Found in red blood cells and carries/delivers oxygen

• Oxygen Saturation: Percentage of hemoglobin that is bound to oxygen

Pneumonia:

• When the alveoli fills up with pus and fluid so it impairs gas exchange, therefore there is a low oxygen saturation

  • CO is high, but Hb is normal and SaO2 is low

What are the different types of Shock?

• Hypovolemic (Hemorrhagic and Non-Hemorrhagic)

• Obstructive

• Distributive

• Cardiogenic

Symptoms of All Shock

• Tachycardia: ↓ cardiac output or ↓ volume so the body compensates with increasing heart rate

• Hypotension: due to loss of blood or sepsis (response due to infection)

• Pale, White and Clammy skin

• Confusion: Not enough oxygen to the brain

• Lactic acidosis and oliguria

• Fast and weak pulse, Fast and shallow breathing

Stages of Shock

Initial, Compensated, Decompensated/Progressive and Refractory

What is the Initial Stage of Shock

Mean arterial pressure decreased less than 10 mmHg. Compensation is effective. No visible changes. The first stage of shock is hard to detect

What is the Compensated Stage of Shock

Body’s primary goal is to maintain blood flow to heart and brain through vasoconstriction (release of epinephrine) and shunting blood to vital organs. Anaerobic metabolism begins to occur. The body maintains perfusion by decreased peripheral blood flow, tachycardia to maintain cardiac output, tachypnea. Distal pulses become weak skin will present as pale, cool, and diaphoretic, and blood pressure initially seems normal. Capillary refill is delayed. Normal BP does NOT rule out shock as the heart rate increases before BP drops

Perfusion:

the delivery of oxygen-rich blood and nutrients to the body's tissues and organs via the circulatory or lymphatic systems

Decompensated/Progressive Stage of Shock

Inability of the body to sustain adequate perfusion. As hypoxia develops the patient becomes confused and disoriented; as blood pressure decreases, distal pulses become difficult to locate. Patient presents with flat neck veins, pale, cool, clammy skin, hypotension, and oliguria (reduced kidney perfusion)

Hypoxia:

dangerous condition where your body, or a part of it, doesn't receive enough oxygen to function properly, and therefore sending someone into a confused state

Refractory/Irreversible Stage of Shock

Impending death as the body is no longer able to adjust for the extreme blood loss; tissue perfusion is negligible, allowing for cellular necrosis due to lack of adequate oxygen tension. Heart function continues to decline becoming slow and irregular; multi-system organ failure occurs.

Diagnosis Through Imaging

Usually can just be diagnosed through symptoms however we can test for lactic acidosis (through inadequate tissue oxygenation by lab studies)

• >4 mmol/L

Overall Treatment Goals for Shock:

• Maximise cardiac output (fluids, blood, vasopressors) and increase oxygenation (intubation or non invasive ventilation)

• Oxygen delivery is needed to increase Cardiac output (CO), Hemoglobin (Hb) and Oxygen saturation (SaO₂) and decrease agitation, fever and work of breathing

What is Hypovolemic Hemorrhagic Shock?

Acute hemorrhage causing rapid reduction in blood volume (red blood cell mass and plasma)

• ↓ Blood volume → ↓ cardiac output → ↓ oxygen delivery

Causes of HHS?

External (trauma) or internal bleeding (abdominal aortic aneurysm, GI sources, blunt trauma, fractures, arterial or venous injury, ectopic pregnancy)

• High Risk leeding Areas: Thorax, Abdomen, Pelvis and Upper Legs (Femur)

Treatment for HHS:

• Volume Resusitation (isotonic fluid to increase volume)

• Blood Transfusion

• If BP is low and actively bleeding (90/60) you want to go to a lower BP than normal because then the body has just enough blood flow to work normally (100/60 rather than 120/80). This prevents further bleeding and dislodging clots

What is Non Hemorrhagic Hypovolemic Shock:

There is no bleeding but loss of fluids (diarrhea or dehydration) 9 Non-hemorrhagic hypovolemic shock arises when volume intake is insufficient to make up for volume losses)

• ↓ Plasma volume → ↓ Cardiac output → ↓ oxygen delivery

What are the Causes of NHHS

• Inadequate fluid intake (tea and toast)

• Excessive output: renal diuresis (diabetes insipidus), gastro-intestinal losses, Insensible losses (skin, respiratory), third space (burns, pancreatitis, peritonitis)

• Metabolic derangements (hyperglycemia, inborn error of metabolism)

How can it be diagnosed as NHHS?

• Sodium levels are elevated,

• Hemoglobin/hematocrit are elevated due to hemoconcentration

• Creatinine is elevated (renal function is decreased)

Treatment for NHHS:

• Oxygenation and Ventilation

• Isotonic fluid resusitation

What is Cardiogenic Shock

Characterized by reduced cardiac output (heart cannot pump enough blood) resulting in decreased oxygen delivery to the tissues

• ↓ Cardiac output → ↓ oxygen delivery despite normal volume

What are the Causes of Cardiogenic Shock?

• Myocardial Infarction that is due to ischemia

How can Cardiogenic Shock be Diagnosed in Hospitals:

• Clinical: chest pain, shortness of breath, syncope, oliguria, altered mental status, hypotension, tachy-or bradycardia, peripheral edema.

• ECG: ischemia or arrhythmias

• Chest-X-ray: pulmonary congestion

• Laboratory: elevated troponin levels

Treatment for Cardiogenic SHock

• Ensure adequate oxygenation and ventilation

• early revascularization with PCI (remove plaque), coronary bypass surgery, or thrombolytics ( dissolve blood clots)

What is Obstructive Shock?

ccurs when extra cardiac obstruction impedes cardiac filling (reduces preload) or impairs cardiac output (increased afterload).

Causes of Obstructive Shock

• Cardiac Temponade

• Pulmonary Embolism: Blood clot trapped in the artery restricting oxygen and blood flow

• Tension pneumothorax: Air is trapped in the chest so it compresses lungs and great veins (vena cava) due to increase in intrathoracic pressure

Symptoms of Obstructive Shock

• Jugular Vein Distention: neck veins popping out

• Blood clots in the veins

Treatment for Obstrucitve Shock:

• Pericardiocentesis (Tamponade) → drain excess fluid from the pericardium

• Relief of tension (Pneumothorax)

• Thrombolysis (Pulmonary Embolism) → clot breakdown

What is Distributive shock:

a medical emergency where severe blood vessel dilation (vasodilation) and leaky capillaries cause a dangerous drop in blood pressure

• therefore blood "spreads out” and does not reach organs effectively

  • eg. Anaphylactic and Septic shock

Causes of Distributive Shock

• Sepsis

• Anaphlaxis

• Hypothermia: Rapid external heat causes the peripheral blood vessels to open up suddenly, sending this cold, acidic blood back into the core circulation, overloading the already strained heart.

• Neurogenic shock

Pulmonary Embolism

• Part of Obstructive Shock

• It comes from a blood clot in one of the pulmonary arteries in the lungs causing restriction of blood flow/shortness of breath

Hypovolemic Shock Symptoms (End):

Low BP, High Pulse, High Respiratory Rate, Vasoconstriction, Pale and Cold

Cardiogenic Shock Symptoms (End):

Low BP, High and Weak Pulse, High Respiratory Rate, Vasoconstriction, Pale and Cold

Obstructive Shock Symptoms (End):

Low BP, Vasoconstriction, High Pulse, High Respiratory Rate, Pale and Cold

Distributive Shock:

Vasodilation, High or Low BP, High or Low Pulse Rate, High or Low Respiratory Rate, Normal/Red and Warm