Surgery - Anesthetic With Heart Disease

Front 1

Anesthetic considerations for a cardiac patient

Back 1

-the safest anesthetic approach to an animal with heart disease is to make a diagnosis
-understand the pathophysiology of the specific cardiac disorder
-determine the progression of the disease in the patient
-understand the normal compensatory responses to the disorder
-choose a protocol that will support rather than decompensate the patient

Front 2

Goals in evaluating your patient prior to anesthesia

Back 2

-presenting complaint
-determine general health status
-discern the progression of heart disease
-current medications and response to them

Front 3

Questions asked to owners regarding:

Back 3

-exercise intolerance
-activity level
-coughing
-current meds

Front 4

How to evaluate a patient's status to determine their ability to safely undergo general anesthesia for dentistry

Back 4

-CBC and biochem
-radiographs

Front 5

Signs to look for during complete physical exam that are commonly associated with heart disease

Back 5

-pallor, cyanosis, slow capillary refill
-weak peripheral pulse
-jugular venous pulse
-edema, ascites, depression
-cough, increased work of breathing

Front 6

Signs to listen for on auscultation

Back 6

-murmurs or abnormal heart sounds
-irregular rhythms
-pulse deficits
-abnormal lung sounds (crackles?---> pulmonary edema)
-percussion for fluid accumulation

Front 7

Minimum data base
-for cardiac patient

Back 7

-CBC
-Serum biochem
-thoracic radiographs

Front 8

Additional data you may want to collect for certain cardiac cases

Back 8

-ECG
-urinalysis
-BP
-SpO2
-arterial blood gas analysis
-heartworm test
-serum thyroid hormone level

Front 9

Essential tool of the cardiologist

Back 9

-ECG

Front 10

ECG
-uses

Back 10

-diagnosis of specific cardiac or vascular anatomic disorders
-evaluation of chamber enlargement and chamber volume
-assessment of heart function

Front 11

Doppler echo
-uses

Back 11

-ID of regurgitant flow
-quantification of pressure gradient across valves

Front 12

Establishing patient risk
-use

Back 12

-helpful to clarify degree of compromise of patient prior to anesthesia

Front 13

ASA classifications of risk

Back 13

I) normal healthy patient
II) mild systemic disease
III) severe systemic disease limiting activity, but not incapacitating
IV) incapacitating systemic disease that is a constant threat to life
V) moribund patient not expected to live 24 hrs

Front 14

CBC
-what to look for

Back 14

-signs of systemic infection
-hematocrit
-total protein
-platelets

Front 15

Serum chemistry
-what to look for

Back 15

-impaired renal or hepatic function in geriatric animal prior to anesthesia

Front 16

If a radiograph is showing left atrial and ventricular enlargement, what is the most likely diagnosis?

Back 16

-chronic valvular disease with mitral insufficiency

Front 17

Questions to ask when you have a likely diagnosis of the heart condition

Back 17

-what is the pathophysiology of the disease?
-how does the animal adapt to the condition?
-what is the risk of anesthesia

Front 18

Effects of mitral valve insufficiency on the heart

Back 18

-chronic volume overload -----> ventricular dilation
-stroke volume is divided into forward and regurgitant flow
-no period of isovolumetric contraction in LV

Front 19

Isovolumetric contraction
-define

Back 19

-when the mitral valve and aortic valve should both be closed to build up some pressure in the ventricle

Front 20

Effect of volume overload

Back 20

-eccentric hypertrophy
-dilation of the ventricle in systole
-normal wall thickness
-systolic function usually ok
-LV wall motion during systole may appear hyperdynamic

Front 21

Why are animals with mitral insufficiency asymptomatic for long periods

Back 21

-afterload is low
-oxygen demand is low
-LVEDP does not increase (no isovolumetric period ---> no increase in wall pressure)

Front 22

Volume of regurgitant flow in mitral insufficiency

Back 22

function of:
-size of mitral valve orifice
-time of flow
-pressure gradient across the mitral valve

Front 23

Regurgitant orafice size is a function of:

Back 23

-left ventricle size

Front 24

Mitral insufficiency
-goal of anesthesia

Back 24

-promote forward flow
-reduce regurgitation

Front 25

Mitral insufficiency
-dynamic factors that increase regurgitant volume

Back 25

Increases in preload
-avoid bradycardia
-avoid IV fluid overload

Increases in afterload
-avoid vasoconstriction

Decreases in contractility
-avoid decreases in sympathetic tone

Front 26

Drug that are ok for vasodilation in mitral valve insufficiency

Back 26

-acepromazine (low dose) with an opioid (analgesia)
-benzodiazepine with opioid
-opioids alone as premed

Front 27

Drug contraindicated for mitral valve insufficiency

-why?

Back 27

-Alpha-2 agonists

-vasoconstriction----> reflex bradycardia
-sympatholytic

Front 28

Drug to consider if bradycardia occurs

Back 28

-atropine

Front 29

Inhalant anesthetics that are vasodilators

Back 29

-isoflurane
-sevoflurane

Front 30

Fluid therapy of patient with cardiac conditions

Back 30

-5 mL/kg/hr or less for maintenance during anesthesia

-base on prior chest radiograph evaluation of pulmonary circulation

Front 31

Reason why local nerve blocks may be a good choice in patients with cardiac problems

Back 31

-removes pain stimulation ----> lighter anesthetic needed

Front 32

Cardiac conditions that constitute major risk

Back 32

-decompensated CHF
-high-grade AV block
-symptomatic ventricular arrhythmias
-supraventricular arrhythmias with uncontrolled rate
-severe valvular disease (pulmonic/aortic stenosis)

Front 33

Principles for the higher risk cardiac patient
-hydration status

Back 33

-insure effective circulating blood volume
-provide adequate preload
-anesthesia usually results in decreased vascular tone, cardiac output
-correct hypoproteinemia

Front 34

Principle for higher risk cardiac patient
-optimizing oxygen-carrying capacity

Back 34

-insure adequate oxygenation (PaO2 = 100 mmHg, SpO2 > 95%)
-insure adequate hemoglobin (PCV > 20%)
-insure adequate cardiac output (SBP > 90 mmHg)

Front 35

Principles for higher risk cardiac patients
-correct arrhythmias

Back 35

-stable rhythm to maximize CO
-correct underlying acid-base/electrolyte disorder
-choice of antiarrhythmic therapy

Front 36

Principles for higher risk cardiac patients
-treat if there is evidence of:

Back 36

-pulmonary edema (diuretics)
-pleural effusion
-pericardial effusion
-pneumothorax

Front 37

Principles for higher risk cardiac patient
-continue administration of current heart medications up to the point of anesthesia if:

Back 37

-the therapy has improved patient condition
-the therapy helps provide hemodynamic or metabolic stability
-acute discontinuation of drug could result in adverse effect

Front 38

Drug you may want to discontinue before anesthesia

Back 38

-Beta-blocker

-negative ionotrope
-hard to deal with accompanied by anesthesia

Front 39

How to choose the correct anesthetic drugs in a cardiac patient

Back 39

-CV disease requires careful choice, titration to effect, balanced approach
-choices based on best understanding of physiologic consequences of the state of cardiac dysfunction