Ruptured Papillary Muscle

•     Acute mitral regurgitation secondary to rupture of papillary muscle:

1.      Trauma

2.      Acute MI

3.      Myocardial abscess

•     Partial or total rupture of a papillary muscle is a rare but often fatal complication of transmural MI

•     Rupture of posteromedial papillary muscle occurs more commonly then rupture of anterolateral papillary muscle

•     Papillary muscle dysfunction occurs in approximately 40% of patients who sustain a posterior septal MI & in 20% of patients with an anterior septal MI

•     Inferior wall infarction can lead to rupture of the posteromedial papillary muscle [= posterior papillary muscle of mitral valve]

•     Anterolateral MI can lead to rupture of anterolateral papillary muscle [= anterior papillary muscle of mitral valve]

•     Rupture of right ventricular papillary muscles is rare

•     Unlike rupture of the ventricular septum which occurs with large infarcts, papillary muscle rupture occurs with a relatively small infarction in approx 50% cases

      therefore  may be seen in modest coronary artery disease

•     In a small number of patients, rupture of more than one cardiac structure occurs [left ventricular wall, interventricular septum, papillary muscles]

Haemodynamic consequences of each type of rupture

initial hear a new holosystolic murmur followed by development of increasing severe heart failure

a) Tricuspid valve

Rupture of right ventricular papillary muscle —>

- massive tricuspid regurgitation

- right ventricular failure

b) Mitral valve

• Note appearance of mitral regurgitation post cardiac failure post MI c.f. mitral regurgitation post papillary muscle rupture

§         Complete transection of left ventricular papillary muscle —>  sudden massive mitral regurgitation - not compatible with life

• Rupture of a portion of mitral valve —> severe mitral regurgitation - more common

·        Acute mitral regurgitation often leads to pulmonary oedema & cardiogenic shock. As opposed to chronic MR (in which a large & compliant left ventricle is present), when acute MR occurs, there is a small non compliant left atrium. Therefore regurgitation of a a given volume of blood into the small atrium produces higher LA & PA pressures then it does in a chronic situation. Severe biventricular failure is common.

Surgery

1] Timing

• Operation should not be delayed in patients with a correctable who require pharmacological &/or IABP support as such patients may develop a serious complication:

-         infection

-         ARDS

-         extension of infarct

-         renal failure

§         However if the patient remains stable after weaning of pharmacological &/or IABP support postponement of surgical repair for 2-4 weeks may allow for some healing of the infarct

• Surgical repair may include insertion of prosthetic valve usual with CABG

2] Surgical

·        Mitral valve replacement should be performed without delay

·        Temporising therapy is of limited therapy

·        Rapid MVR yields good results although the risks are high

3] Anaesthetic

·      Avoid slow HR, high SVR & excessive preload as well exacerbate regurgitation

·      Hypocapnia & avoidance of NO can help to reduce high PA pressures