MI complications (from Acute coronary syndromes) Flashcards
There are 2 types of MI complications that are immediately life threatening
What are they?
Mechanical complications - structural
Ventricular arrhythmic complications - functional
Aside from mechanical complications & VA complications, what complication can arise from MI?
LV thrombus
less threatening but still needs treated
What is meant by mechanical complications of MI?
Tearing or rupture of infarcted myocardium.
15% of all AMI deaths
3 main complications:
- Free Wall Rupture - 10-12%
- Papillary Muscle Rupture - 1-2%
- Rupture of IVS (VSD) - 1-2%
What is a free wall rupture?
Type of mechanical complication of MI, where the wall of the heart tears
85% occur in the first week and 1/3 in first 24 hours
LAD territory most common, but always at the edge of the infarcted area.
Leads to haemopericardium & acute tamponade
What is the outcome of free wall rupture?
Sudden EMD death unless adhesions or false aneurysm contain pericardial effusion
If possible urgent echo, pericardiocentesis and drainage with pigtail catheter.
If survives initial episode immediate surgery but rare.
Who is most at risk of a free wall rupture?
More common in:
Elderly
Females
Hypertensive
Anterior MI
What is a Septal wall rupture?
Type of mechanical complication, when the intraventricular septum tears
Anterior MI = Apical septal rupture
Inferior MI = Basal septal rupture
Most patients have multi-vessel Coronary artery disease
What is a papillary muslce rupture?
Mechanical complication in which the papillary muscles controlling the heart valves tear
Type of MI determines which one is ruptured:
- Inferior MI (PDA) - post/med muscle
- Ant/lat MI (LAD Cx) - ant/lat muscle
What is the prognosis of papillary muscle rupture?
Nae good
Complete trans-section is incompatible with life
Mortality high with medical Rx:
- 33% die immediately
- 50% die 24hrs
- Only 6% live > 2 months
What 2 mechanical complications can occur together?
Papillary muscle rupture & Septal rupture
Sudden major haemodynamic compromise
Generally happens within a week of MI
What are the symptoms of Papillary muscle & septal rupture?
Symptoms:
- Sudden severe breathlessness (MVR)
- Autonomic activation eg sweating, nausea & vomiting
- Chest pain
What are the signs of papillary muscle & septal rupture?
Shock, tachycardia, pulmonary oedema
Harsh systolic murmur:
- Septal rupture at left septa edge = right chest murmur
- Mitral valve muscle rupture = back murmur (may be absent)
Right parasternal heave
Palpable thrill
Elevated JVP
How would you differentiate between Septal rupture & Papillary muscle rupture?
Papillary muscle rupture:
- tends to cause more SOB & oedema (Mitral valve)
- Inferior MI
Septal rupture:
- JVP more elevated
- Anterior MI
What are the investigations for mechanical complications of MI?
Echo
Right catheter
Left catheter
What would you look for an echo that would indicate mechanical complications of MI?
Prolapsing mitral leaflet +/- chunk of muscle.
Broad MR jet into normal sized LA.
Septal rupture (VSD) - easily missed.
RV size, function and pressure is a strong predictor of outcome with septal rupture (VSD)
What would mechanical complications of MI show on a right heart catheter?
Step up in O2 sats with septal rupture (VSD)
Confirms Diagnosis and quantifies shunt
Large v waves on wedge with acute MR
What is the purpose of investigating mechanical complications of MI with a left heart catheter?
Establish coronary anatomy
Better localisation of pathology
How is papillary muscle rupture and septal rupture managed?
Medical management only temporary:
1) I.V. Nitrates if SBP > 90mmhg
2) Inotropes if SBP < 90mmhg
3) IABP (balloon pump):
- Reduce afterload
- Augment DBP
Call cardiac surgeons
How is papillary muscle rupture & septal rupture surgically treated?
Mitral valves are usually replaced rather than repaired.
Septal rupture = repair with pericardial or synthetic patch.
Coronary artery bypass if needed & possible.
If survive acute episode long term prognosis is good.
What are the types of Ventricular arrhythmic complications?
Ventricular tachycardia (VT)
Ventricular fibrillation (VF)
What is Ventricular tachycardia?
Broad complex, regular, generally rapid tachycardia.
Initiated by ventricular premature beat, sustained by re-entry loop
What is ventricular fibrillation?
Irregular, ineffectual ventricular fibrillating activity
Multiple wavelets of electrical activity
Following an MI, when can Ventricular tachycardia occur?
Can occur at any time after an MI
What causes ventricular tachycardia?
The effects of the MI:
- VT may be driven by ischaemia and/or myocardial damage from the MI
Is ventricular tachycardia always symptomatic?
No
In some, it can be haemodynamically tolerated, despite the poor ventricular function
If a patient has sustained Ventricular tachycardia, what must be done?
If sustained, urgent cardioversion required, usually electrically but also possible by amiodarone or pacing.
Medical therapy +/- implantable cardioverter-defibrillator (ICD) with anti-tachycardia pacing
How would Ventricular fibrillation show up on an ECG/EKG?
P-waves and QRS complexes are not present
Heart rhythm is highly irregular
The heart rate is not defined (without QRS complexes)
Why is ventricular fibrillation a medical emergency?
Can deteriorate into V-fib arrest (asystole)
What type of MI is more likely to lead to a LV thrombus?
Apical/antero-apical MI
With resulting significant LV dysfunction
How long does it take after an MI before an LV thrombus occurs?
Seen after 48 hours
This is why early echos done in CCU should be repeated if above infarct pattern
What medication is given to those with an LV thrombus?
Warfarin (anti-coagulant) for 6/12
