LV Aneurysm

Definition

i) Paradoxical (dyskinetic) systolic expansion of a portion of the ventricular wall

ii) A localised dilatation or saccular protrusion in the wall of the left ventricle, occurring most often after a myocardial infarction.

iii) Scar tissue is formed in response to the inflammatory changes of the myocardium — this tissue weakens the myocardium allowing its walls to bulge outward when the ventricle contracts.

Incidence:

i) Common — 12-15% Post massive (transmural) myocardial infarction

ii) Rare — Young persons with bizarre type of cardiomyopathy

Post MI:

i) Usually [80%] affects anterior wall & apex of left ventricle

§ region supplied by [occluded] left anterior descending coronary a.

§ most are true aneurysms

iii) Aneurysm of posterior left ventricle

§ occurs rarely [5-10%] even post a massive infarct here

§ 50% are false aneurysms

Types

I] ANATOMIC (little functional effect)

i) True aneurysm

— protrudes during both diastole & systole

— has a mouth that is ≥ maximal diameter of aneurysm

— aneurysm wall was originally part of ventricular wall

— composed of fibrous tissue ± residual myocardial cells

— may contain thrombus

— never ruptures once healed

ii) False aneurysm

— protrudes during both diastole & systole

— has a mouth that is < maximal diameter of aneurysm

— aneurysm wall is composed of parietal pericardium and thrombus

— almost always contain thrombus [source of emboli]

— often ruptures

— represents a myocardial rupture site

II] FUNCTIONAL

i) Functional left ventricular aneurysm

— protrudes during systole but not during diastole

— composed of fibrous tissue ± residual myocardial cells

Complications

1) Mitral Incompetence

• Aneurysm of posterior left ventricle

• as post wall of LV supports papillary muscle & chordae tendinae of mitral valve —> mitral incompetence

2) Cardiac failure

• 50% with mod erate or large aneurysms present with symptoms of heart failure ± angina

3) Mural rupture—> tamponade &/or cardiogenic shock

· Pericardial tamponade is the initial problem

· Should initially augment preload & drain effusion (pericardicentesis)

· Surgeon debrides & reconstructs the ventricular wall often using pericardial graft

· The mitral wall is closely inspected for function

· Weaning from CPB requires careful titration of vasodilator & inotropic drugs to minimise ventricular wall tension which can damage the repair while maintaining adequate systemic perfusion

4) Arrhythmias

• A typical sign of the ventricular aneurysm is a recurrent ventricular arrhythmia that does not respond to antiarrhythmic drugs
• 15% have symptoms related to ventricular arrhythmias

5) Embolic source

• 50% of patients with aneurysms have thrombosis
• Embolic events occur infrequently, tending to occur within the initial 4 — 6 months after infarction

6) Miscellaneous

• Angina pectoris may no longer be present because the pain receptors on the anterior wall are destroyed along with the myocardium itself
• 75% of patients with aneurysms have multivessel coronary artery disease
• 25% have symptoms of severe angina alone