VTS: Cardiac emergencies and ECGs

Home

Get App

Create

3 layers of heart:
- 1. Epicardium - outside layer over myocardium
- 2. Myocardium - cardiac muscle
- 3. Endocardium - lines atrial/ventricular cavities
Right = __________ circulation

Systemic
Left = _____________ circulation

pulmonary
__⇾__⇾__⇾__⇾__⇾__⇾__⇾__⇾__⇾__⇾__

Cranial/caudal vena cava ⇾ R atrium ⇾ Tricuspid valve ⇾ R ventricle ⇾ pulmonary arteries ⇾ lungs ⇾ pulmonary vein ⇾ L atrium ⇾ mitral valve ⇾ Left ventricle ⇾ aorta
Wall between arteries

interatrial septum
wall between ventricles

interventricular septum
Majority of cardiac mass =
- L ventricle
- thick walled
Chordae tendineae

fibromuscular strands that help secure cardiac valves
Arteries
- 1. thick walled
- 2. have associated pulse
- 3. carry oxygenated blood from heart to body
capillaries
- 1. small exchange vessels
- 2. fluid passes from capillaries to tissue interstitium
- 3. some fluid moves back into capillaries
veins
- 1. thin walled
- 2. little to no pressure
- 3. carry deoxygenated blood back to heart
preload:

volume of blood in L ventricle just before it contracts
Major determinate of preload

systemic venous constriction or dilation
dilated vein affects preload how?

decreased blood in L ventricle, decreased preload
constricted vein affects preload how?

increased blood in L ventricle, increased preload
How does elasticity affect preload?

stiff/fibrotic myocardium causes decreased ventricular filling
Afterload

resistance to L ventricular ejection of blood at the point of peak tension in wall of ventricle
How does SVR affect afterload?
- Dilated vein = decreased resistance
- Constricted vein = increased resistance
Increasing HR may be from (6)
- 1. volume loss
- 2. pain
- 3. hypoxemia
- 4. hypocapnia
- 5. sepsis
- 6. decreased SVR
What HR will cause decreased CO

HR 2 times normal rate
Bradycardia causes (6)
- 1. high vagal tone
- 2. atrioventricular conduction disturbances
- 3. hyperkalemia
- 4. severe hypothermia
- 5. drugs
- 6. increased intracranial pressure
What BP is dorsal pedal palpated at

60 - 70 mm Hg
What BP is femoral palpated at

40 mm Hg
Pulse wave

difference between systolic & diastolic pressure
ECG

rate and rhythm of heart
Arterial blood pressure is a product of
- CO
- Vascular capacity
- Blood volume
How does body compensate when 1 part of arterial blood pressure suffers?
- Other 2 compensate
- Stimulated by adrenomedullary and neurohormonal stress reactions:
- Catecholamines, renin-angiotensin system
- Temporary
3 main types of BP monitoring
- Oscillometric
- Ultrasonic (doppler)
- Direct (arterial)
Hand-held pump for doppler bp

Sphygmomanometer
How to tell systolic/diastolic with ultrasound BP
- First pulse sound = systolic
- Change to "swishing" sound is diastolic
3 good locations for arterial catheter
- Dorsal metatarsal
- Ventral coccygeal
- Palmar metacarpal
When does oscillometric and ultrasonic BP have decreased accuracy
- Hypotension
- Tachycardia
Normal BP values
Systolic
Diastolic
MAP
- 100-160
- 60-110
- 80-120
- mmHg
Pulse pressure

difference between systolic and diastolic
3 main causes of hypotension
- hypovolemia
- poor cardiac output
- systemic vasodilation
Hypovolemia
- extracellular fluid deficits
- vascular volume deficits
Poor cardiac output
- myocardial failure
- valvular dz
- pericardial tamponade
- severe brady/tachycardia
- arrhythmias
Systemic vasodilation
- Sepsis
- anaphylaxis
- vasodilatory drugs
What BP requires immediate tx
- Systolic <80
- MAP <60
Hypertension - what MAP can cause problems

MAP >140
What can hypertension cause
- retinal detachment
- hemorrhage
- increased ICP
- excessive afterload
2 equations for MAP

MAP = [ (2 x diastolic) + systolic] / 3

MAP = diastolic + (systolic - diastolic)
CVP

central venous pressure
CVP is affected by
- Intravascular volume
- venous tone and compliance
- intrathoracic pressure
- cardiac function
Primary indication of CVP monitoring
- Assessing fluid therapy w/
- renal dz
- pulmonary dz
- cardiac dz
- septic shock
Normal CVP
- 0-5 ccH20
- OR
- 0-3 mmHg
What does CVP monitoring rely on

Trends
Causes of increased CVP
- 1. volume overload
- 2. pleural/pericardial effusion
- 3. pulmonary edema
- 4. pulmonary thromboembolism
- 5. pneumothorax
- 6. pulmonary hypertension
When placing CVP catheter, where is it placed
- Long jugular cath
- tip just cranial to heart
COP
- colloid oncotic pressure
- measures holding pattern of fluids in vascular compartment
decreased COP causes

third spacing
causes of decreased COP
- hypoproteinemia
- increased capillary permeability
What is a good indicator of COP

Refractometer - TP
What TP is a good indicator for colloid use

<3.5 mg/dl
When colloids are being used, what is a good assessment tool for COP
- Refractometer/TP can be skewed
- Colloid osmometer better assessment
Normal COP colloid osmometer

18-25 mmHg
What colloid osmometer reading indicates the use of coloids

<15 mmgh
What colloid osmometer reading usually indicates third spacing

single digits
lactic acidosis

inadequate tissue oxygenation associated with impaired perfusion
Major sources of lactate
- skeletal muscle
- GI tract
Normal lactate

<1.0 mmol/L
Common causes of lactic acidosis
- hypovolemia
- thromboembolism
What electrolytes affect the heart
- K
- Ca
- Mg
- Na
What electrolytes are important for cardiac function
- Ca
- Mg
- Na
heart failure
- heart that pumps inadequate volume of blood to all tissues of body
- Causes inadequate tissue perfusion
- NOT a diagnostic indicator of underlying cause
Clinical signs of heart failure
- +/-
- congestion
- poor peripheral perfusion
- systemic hypotension
CHF
- congestive heart failure
- more specific than heart failure
- impaired cardiac function resulting in increased venous and capillary pressures
CHF leads to (with increased venous and capillary pressure)

organs congested with blood or edematous fluid
3 types of CHF
- R ventricular failure
- L ventricular failure
- Biventricular failure
R ventricular CHF

result of decreased CO and systemic hypertension
Common clinical signs of R CHF
- weakness
- exercise intolerance
- syncope
Common PE findings R CHF
- pallor
- jugular venous distension and pulsation
- enlargement of liver or spleen (congestion)
- tachypnea
- peritoneal or pleural effusion
Diagnostic for R CHF
- CVP (increase)
- Rads -
- +/-
- ascites
- cardiomegally
- pleural effusion
Left ventricular CHF
- similar hx to R CHF
- +/-
- cough
- orthopnea
- hemoptysis
- oliguria
hemoptysis

coughing up blood
PE findings L CHF
- +/-
- abnormal cardiac rhythm
- heart murmur
- auscultable lung crackles
- cyanosis
common diagnostics L CHF
- ekg
- rads
- arterial BP
- general blood profile
Common EKG findings L CHF

=/- arrythmias due to myocardial ischemia or atrial enlargment
common rad findings L CHF
- often pulmonary edema
- or pleural effusion in cats
- +- cardiomegally
arterial bp L CHF

often decreased
common blood panel changes L CHF
- pre-renal azotemia
- hypoproteinemia
- mild-mod increased LES
Biventricular CHF
- combination of L/R CHF signs
- along with +/- arterial thromboembolism
- cachexia

Author

anubis_star

357949

Card Set

VTS: Cardiac emergencies and ECGs

Description

Updated

2022-04-11T02:56:34Z

Show Answers