Preassessment of Heart Disease

Angina Classification
Predictors of increased cardiac risk
Risk stratification of non-cardiac surgical procedures.
Further assessment
Drugs pre-op
Pacemakers

Angina Classification
(Canadian Cardiovascular Society)

Class 0
No angina

Class I
'No angina on ordinary physical activity'
- angina on rapid, strenous prolonged exertion.

Class II
'Slight limitation to ordinary activity'
- walking two blocks
- climbing >1 flight of stairs
- physical activity in cold, after eating.

Class III
'Marked limitation of ordinary activity'
- pain occurs on ordinary activity

Class IV
'Can't carry out any physical activity'
- angina even at rest.

Predictors of Increased Peri-op Cardiovascular Risk
(American College of Cardiology)

Note the risk is increased with abdominal and thoracic surgery
- and is related to length of operation.

Major
Recent MI
- 7-30 days
- and evidence of important ischaemic risk (by symptoms or non-invasive study)
- any MI in the last 6 months should preclude elective surgery
Class III or IV angina
Decompensated CHF
High-grade AV block
Symptomatic ventricular arrythmias with underlying heard disease
Supraventricular arrhythmia and uncontrolled ventricular rate
Severe valvular disease

Intermediate
Class I or II angina
Prior MI
- or pathological Q-waves
Compensated / prior CHF
Diabetes mellitus

Minor
Advanced age
Abnormal ECG
- LBBB, ST abN, LVH
Rhythm other than sinus
- eg AF
Low functional capcity
- eg can't climb flight of stairs with a shopping bag
Prior stroke
Uncontrolled HTN

Chance of Reinfarction
60% if procedure <3-weeks post MI
27% if <3 months post MI
11% chance if 3-6 months post MI

Risk of Procedures
(American College of Cardiology)

High risk
(Reported >5%)
Emergency major operations
- esp in elderly
Aortic / other major vascular
Peripheral vascular
Prolonged surgery
- with large fluid shifts
- or large blood loss

Intermediate risk
(Reported risk <5%)
Carotid endarterectomy
Head / neck procedures
Intraperitoneal
Intrathoracic
Orthopaedic
Prostatic

Low risk
(Reported <1%)
- do not generally require further pre-op cardiac testing.
Endoscopic procedures
Superficial procedures
Cataract procedures
Breast procedures

Further Assessment
(Duke Activity Status Index)
(American Heart Association Exercise Standards)


Major Risk Pts
All patients should have full cardiovascular evaluation

Intermediate Risk Pts
Further risk statified according to functional capacity
- ie metabolic equivalent levels (METs)
Excellent: >7 METs
Moderate: 4-7 METs
- further evaluation if high-risk procedure
Poor: <4 METs
- all get further evaluation

1 METs
-3 METs
Can you take care of yourself?
Eat, dress, use toilet?
Walk indoors around house?
Walk a block or two at 3-5 km/h
Do light work around house

4 METs-9METs
Climb a flight of stairs
Walk up a hill
Walk on ground at 6.4km/hr
Run a short way
Heavy work around house
Moderate recreational activities eg dancing, bowling, doubles tennis.

10 METs
Strenous sports

Low risk pts
Non-cardiac surgery is generally safe regardless of type.

Drugs

All cardiac drugs should be continued up to and including the day of operation.
--> and recommenced at the earliest opportunity post-operatively.
- except aspirin or warfarin obviously.
Continue hypertensives including on morning of operation.

Pacemakers

There are two-types:
- fixed demand (simple)
- demand (complex)
Vital to be aware that diathermy can inhibit the demand type
- less likely to interfere with the simple type.
If you are in any doubt contact a cardiologist.

Notes
- Any pt with a pacemaker requiring surgery should have a recent cardiology review to ensure it is functioning correctly.
- Use short rather than long bursts of diathermy
- The earthing pad should be placed on the leg - ie as far from the pacemaker as possible.
- Bipolar is safer than unipolar
- Avoid using diathermy near the pacemaker
- Always monitor with ECG.