Preoperative diagnosis of acquired valvular disease

Low-Gradient Severe Mitral Stenosis: Hemodynamic Profiles, Clinical Characteristics, and Outcomes

Background Optimal management of patients with severe mitral stenosis ( MS ) and low transmitral gradient is incompletely understood. Methods and Results We examined 101 consecutive patients with severe rheumatic MS (mitral valve area ≤1.5 cm²) who underwent balloon valvuloplasty. Low gradient was defined as mean transmitral gradient <10 mm Hg and low flow as stroke volume index ≤35 mL/m² by echocardiography. Symptoms and mortality data were collected. Systolic, diastolic, and arterial function were characterized by measuring left ventricular (LV) end-systolic elastance, LV stiffness constant (β), diastolic capacitance (predicted LV end-diastolic volume at a common LV filling pressure of 30 mm Hg), and effective arterial elastance. Low gradient (<10 mm Hg) was present in 55 patients, including low flow/low gradient in 11 and normal flow/low gradient in 44 patients, and high gradient was present in 46 patients. Participants with low-flow/low-gradient (LG) MS were older with higher rates of atrial fibrillation (64%) and subvalvular thickening, higher afterload, and decreased LV compliance with lower ejection fraction (57±10% versus 65±4% versus 63±6%, P=0.002) but similar end-systolic elastance compared with patients with normal-flow/ LG and high-gradient MS . The normal-flow/ LG group had larger mitral valve area and lower left atrial pressure by catheterization, as well as favorable long-term outcomes compared with the low-flow/ LG and high-gradient MS group. A total of 40% of patients with LG MS had no symptomatic benefit from valvuloplasty compared with 18% of patients with high-gradient MS ( P=0.02). Conclusions Presence of low gradient in patients with severe MS was associated with lesser symptomatic benefit from valvuloplasty. In the subset with low stroke volume index, this may be related to independent ventricular-vascular uncoupling, decreased LV compliance, and high prevalence of atrial fibrillation in addition to intrinsic MS .

Severely symptomatic mitral stenosis with a low gradient: a case for low-technology medicine

We have observed a group of patients with mitral valve disease and severe symptoms but also with low transmitral gradients and normal cardiac outputs who defy the traditional hemodynamic explanation of mitral stenosis. We performed a 10-year retrospective chart review of all mitral valve replacements at our institution to further characterize this population. The study group consisted of 16 of 132 patients (12%) with symptomatically severe (New York Heart Association [NYHA] class 3.3 +/- 0.5) mitral stenosis but a low (< 10 mm Hg) transmitral gradient, a normal cardiac output (4.8 +/- 1.2 L/min), and a preserved valve area (1.6 +/- 0.4 cm2). Sixteen patients were randomly chosen from the remaining group to serve as a comparison population. Study patients were noted to have less atrial fibrillation, lower wedge and mean pulmonary artery pressures, and a higher incidence of subvalvular disease identified at the time of surgery than did the comparison population. Left ventricular end-diastolic pressure and cardiac output did not differ. Study patients did well with surgery and reported an excellent functional benefit. We believe that this subgroup of patients with mitral valve disease is important, may be missed by using conventional criteria of valve area to determine timing of surgical intervention, and may have their symptoms primarily because of subvalvular disease. Further and perhaps most important, this group illustrates the ongoing need for careful clinical assessment skills and judgement in the face of ever-increasing technology.

The Syndrome of Severe Mitral Regurgitation with Normal Left Atrial Pressure

It has been generally thought that significant elevations of the left atrial and pulmonary vascular pressures occur in patients with mitral regurgitation of sufficient severity to produce serious disability and gross enlargement of the left atrium. Ten patients with severe mitral regurgitation have been encountered in whom gross left atrial enlargement was accompanied by normal left atrial and pulmonary artery pressures. These patients ranged in age from 8 to 49 years, all were in functional classes III or IV, and the average duration of symptoms was 7.3 years. Nine patients had rheumatic mitral regurgitation while one had a congenital lesion. Atrial fibrillation and the physical findings of pure mitral regurgitation were present in all patients, as was striking left atrial enlargement on their roentgenograms. Left atrial pressure, determined by left heart catheterization, averaged 9.1 mm. Hg and did not exceed 12 mm. Hg in any patient, and the V wave was not particularly prominent. The cardiac index was markedly depressed and averaged 2.0 L./min./M. 2 B.S.A.

The observed discrepancy between left atrial size and pressure must reflect a disturbance in the compliance of the left atrial wall. It is suggested that long-standing mitral regurgitation may modify the mechanical characteristics of the atrial wall and that the presence of a normal left atrial pressure must not be assumed to exclude the presence of severe mitral regurgitation. The manner in which variations in left atrial compliance affect the clinical picture of mitral regurgitation and the selection of patients for operative intervention are discussed.