Pulmonary Impedance and Wave Reflections in Adults with Mitral Stenosis: Immediate and Follow-Up Effects of Balloon Valvuloplasty.

Abstract

Purpose: We compared adults with mitral stenosis (MS) to 8 controls (CONT) to see how pulmonary impedance and wave reflections differ at baseline and after balloon valvuloplasty.

Methods: We separated the MS patients into groups according to mean pulmonary artery pressure: moderate (MOD; ≤ 26 mmHg, n = 21) and high (HIGH; > 26 mmHg, n = 33). We made baseline high-fidelity measurements in all patients, in the MS groups after vasodilation with nitroprusside, immediately and 4 months after balloon valvuloplasty.

Results: Comparing MOD vs CONT, using the Kruskal-Wallis test with Bonferroni correction, reveals evidence for higher baseline input resistance (R) (489 vs 205 dyne-sec/cm⁵, P = 0.07); first harmonic of impedance modulus (Z₁) (97.3 vs 27.6 dyne-sec/cm⁵, P = 0.01); first zero crossing of impedance phase angle (F₀) (4.49° vs 2.19°, P = 0.02) but no difference in wave reflection index (P_b/P_f). Baseline HIGH vs CONT comparisons reveal stronger evidence and larger differences than MOD for R (995 vs 205, P < 0.001); Z₁ (151 vs 27.6, P < 0.001); F₀ (5.25 vs 2.19, P < 0.001); as well as P_b/P_f (0.69 vs 0.42, P < 0.001). Responses to nitroprusside and valvuloplasty are also greater in the HIGH than MOD, but the HIGH parameters still differ from the CONT. Four months after valvuloplasty there is evidence for reverse remodeling in both groups. Further analyses reveal that sinus rhythm and younger age are potentially important factors for remodeling.

Conclusion: MS causes alterations in pulmonary hemodynamics that differ according to pressure levels. These changes are only partially reversed immediately after valvuloplasty. There is evidence for reverse remodeling 4 months afterwards.