11.4.2 Acute valvular insufficiency

 

 Massive and sudden valve leakage leads to a cascade of complications: ventricular dilatation, LV failure, tachycardia, hypotension, cardiogenic shock and pulmonary oedema. There are many common causes [2].

 The clinical picture is one of cardiogenic shock, along with chest pain in case of dissection or fever in case of endocarditis. The patient is tachycardic, hypotensive, dyspnoeic and tachypnoeic. The echocardiographic criteria for severity do not apply well to these highly unstable situations where the regurgitant volume changes easily as a function of SAR, preload or contractility. Because the pressure regime is low and the regurgitant orifice is large, the V_max of the insufficiency jet is greatly reduced; the extent of the colour jet underestimates the size of the regurgitant volume. However, the width of the jet at its origin (vena contracta) remains a reliable criterion for quantifying the lesion. CT or MRI may provide more accurate images if echocardiography is incomplete. Catheterisation is not useful; only coronary angiography may be necessary if the patient has had an ischaemic MI and has coronary symptoms. Treatment is primarily surgical, with medical treatment (vasodilators, inotropes, IPPV) only as stabilisation phase. Intra-aortic balloon pump (IABP) is very useful in MI but contraindicated in AI. 

 

 

Although compliant, the LA cannot accommodate the increase in volume caused by MI because it is not dilated; its pressure rises, a "v" wave of ≥ 30 mmHg is seen on the PCWP curve, and pulmonary oedema develops rapidly. The left ventricle experiences a large volume overload as part of the stroke volume only flows back and forth between the LV and the LA. The presence of a severe MI during an episode of acute coronary ischaemia is a major factor in mortality regardless of treatment; if surgical revascularisation is indicated, simultaneous correction of the MI improves the prognosis [1]. Whenever possible, mitral valve repair is always preferable to valve replacement, except in cases of complex pathology where the operative time is excessively long [2].

 

 

The left ventricle also experiences massive volume overload, but at a much higher pressure as it is filled by aortic pressure during each diastole. Cardiogenic shock lowers systolic pressure, so differential pressure is not a criterion of severity in acute aortic insufficiency. The sudden rise in LV diastolic pressure causes premature closure of the mitral valve; the LA empties poorly into the LV and PCWP underestimates true LV end-diastolic pressure. Myocardial ischaemia is common because coronary perfusion pressure is greatly reduced: aortic diastolic pressure is low and left intraventricular pressure is high.  

 

 

Acute valvular insufficiency

Etiologies:  - AI: endocarditis, A dissection, trauma - MI: abutment/cordage rupture, endocarditis, LV decompensation (functional MI), akinesia   Acute (ischaemic MI) - Prosthesis: blocked winglets, tears, paravalvular leakage   Compared with a long-standing deficiency, an acute deficiency is characterised by - Lack of adaptation and remodelling - Severe ventricular failure - Emergency surgery   The echocardiographic criteria for chronic regurgitation are poorly applicable. Due to cardiogenic shock and arterial hypotension, the extent of the colour jet and its Vmax are greatly reduced.