5. Acute myocardial infarct

Question 1

You are asked to assess a 55-year-old male patient for an open reduction
and internal fixation of a wrist fracture.

He gives a history of acute myocardial infarction (AMI) 4 years ago, but does not remember which
tablets he is on.

He gives no recent history of chest pain, his previous AMI was painless.

A routine pre-operative ECG has been done.

What does it show?

Answer 1

The findings on this ECG are:

Rate: 50 bpm (300/6)

Rhythm: Normal sinus rhythm with borderline first-degree heart block.
The PR interval is just over five small squares.

Axis: + 45 degrees (see atrial flutter question for method).

P waves: Normal.

QRS: Normal.

ST: ST elevation in leads II, III and aVF in keeping with acute
inferior myocardial infarction. There is ST elevation in V6
suggesting lateral involvement. There are reciprocal ST
changes in V1–V3.

T waves: There is T wave inversion in V1–V3.

In summary, the ECG shows an acute inferior (infero-lateral) myocardial
infarction.

Question 2

What medication would you expect the patient to be on?

Answer 2

2017 ESC Guidelines

The following interventions are beneficial in the majority of patients with NSTEMI or unstable angina who have undergone early interventions:

*Beta blockers.

*Statins.

*Aggressive management of recurrent myocardial ischemia or reinfarction.

*Aspirin and P2Y12 receptor blocker therapy is indicated in all patients after NSTEMI for at least one month and up to a year, irrespective of whether revascularization or stenting occurs.

*Angiotensin converting enzyme inhibitors in most patients.

Question 3

What are the anaesthetic implications of these drugs?

Answer 3

1. Aspirin
   Potential to increase bleeding.
   Usually stopped 7 days before
   surgery with high risk of bleeding
2. Clopidogrel
   Increases bleeding risk and is best stopped at least 7 days
   before surgery and peripheral or central nerve blockade
3. ACEI
   Increase the incidence of hypotension during induction of
   general anaesthesia. Some authors suggest omitting the day
   before surgery
4. Betablockers
   While they may increase the risk of bradycardia, beta-blockers
   have been shown to reduce cardiac mortality post-non-cardiac
   surgery in patients with, and at risk of ischaemic heart disease
   (Mangano et al., 1996). This is thought to be via their
   favourable effects on cardiac oxygen demand and by
   attenuation of the stress response.
5. Diuretics
   May result in hypovolaemia and electrolyte disturbance
6. Statins
   May have cardio-protective properties, but further research is
   needed to assess efficacy.

Question 4

How would you assess this patient?

Answer 4

Perform an ABC assessment of the patient and take a history.

Airway: Administer oxygen via reservoir bag at 15 litres per minute

Breathing: Look, listen and feel. Looking for signs of left ventricular failure

Circulation: Look, listen and feel. Check HR, BP, JVP, capillary refill, heart
sounds and urine output assessing for signs of cardiac insufficiency

History:

Question 5

History:

Answer 5

Symptoms that may suggest time of recent AMI –
chest pain, jaw pain, arm pain, SOB, nausea, sweating.

Symptoms of cardiac failure and functional limitation –
SOB, orthopnoea, PND, swelling.

Previous cardiac history.

Risk factors for AMI –
smoking, hypertension, diabetes,
hypercholesterolaemia, obesity, and family history.

Previous medical history.

Drug history and allergies.

Anaesthetic history.

Question 6

What are the symptoms and signs of R heart failure?

Answer 6

Right heart failure symptoms:

Fatigue
SOB
Nausea
Swelling

Right heart failure signs:

Raised JVP
Hepatic engorgement
Pitting oedema
Ascites and pleural effusions
Third heart sound
Tricuspid regurgitation (dilation of ventricle).

Question 7

What are the symptoms and signs of L heart failure?

Answer 7

Left heart failure symptoms:

Fatigue
Exertional dyspnoea
Orthopnoea
Paroxysmal nocturnal dyspnoea
Respiratory distress if pulmonary oedema.

Left heart failure signs:

Cardiomegaly with displaced apex
Third or fourth heart sounds
Mitral regurgitation
Basal crackles
Frank pulmonary oedema.

Congestive heart failure occurs when right ventricular failure occurs, secondary
to left ventricular failure. It will present as a combination of the above.

Question 8

NYHA classification of cardiovascular disease

Answer 8

Class Patient symptoms

Class I (Mild)
No limitation of physical activity. Ordinary physical
activity does not cause undue fatigue, palpitation, or
dyspnoea (shortness of breath).

Class II
(Mild) Slight limitation of physical activity.
Comfortable at rest, but ordinary physical activity results in fatigue,
palpitation, or dyspnoea.

Class III
(Moderate)
Marked limitation of physical activity. Comfortable at rest,
but less than ordinary activity causes fatigue,
palpitation, or dyspnoea.

Class IV
(Severe)
Unable to carry out any physical activity without discomfort.
Symptoms of cardiac insufficiency at rest.
If any physical activity is undertaken, discomfort is increased.