Effectiveness of percutaneous mechanical mitral commissurotomy using the metallic commissurotome in patients with restenosis after balloon or previous surgical commissurotomy

Percutaneous transmitral commissurotomy in juvenile mitral stenosis—comparison of long term results of Inoue balloon technique and metallic commissurotomy

OBJECTIVES

To compare the immediate and long term results of percutaneous mitral valvotomy using metallic commissurotome and Inoue balloon in juvenile mitral stenosis.

BACKGROUND

Inoue balloon technique for mitral commissurotomy (IBMC) is well established and carried out worldwide in the treatment of juvenile mitral stenosis. Percutaneous mitral metallic commissurotomy (PMMC) is reported to be a cheaper and effective alternative to balloon mitral commissurotomy.

METHODS

Thirty-three patients aged less than 20 years, who underwent PMMC, were compared with 33 age and sex matched control patients who underwent IBMC. Success of valvotomy, procedure related complications, and follow-up events of the two techniques were compared.

RESULTS

Basal echocardiographic and hemodynamic data were similar in both groups. Procedural success was similar in both groups, 31/33. Complications like cardiac tamponade and mitral regurgitation (requiring or not requiring mitral valve replacement) were similar in both groups. On follow-up of more than 3 years, both groups had comparable hemodynamic parameters and restenosis rates.

CONCLUSIONS

Both IBMC and PMMC are successful in providing relief from severe juvenile mitral stenosis in terms of gain in valve area and reduction in transmitral gradient. Both techniques have similar procedural success and complication rates. The long term follow-up results are comparable at follow-up of more than 3 years.

The clinical and hemodynamic results of mitral balloon valvuloplasty for patients with mitral stenosis complicated by severe pulmonary hypertension

BACKGROUND

Percutaneous balloon mitral valvuloplasty (PBMV) has become the procedure of choice for isolated, uncomplicated mitral stenosis (MS) with favorable morphology and may be a useful method for surgical high-risk conditions such as advanced age, the presence of severe tricuspid regurgitation, New York Heart Association (NYHA) class IV at presentation, and severe pulmonary hypertension (PH). The development of PH is a common and important sequela in patients with advanced mitral stenosis and is associated with hemodynamic and clinical decompensation. However, the influence of PBMV on patients with severe PH has seldom been evaluated. Our objective was to probe into the immediate and long-term effects of PBMV on patients with MS complicated by severe PH and to predict the factors that determine the prognosis of patients with severe PH.

METHODS

We included 44 patients with MS complicated by severe PH (systolic pulmonary pressure >80 mm Hg, group S) and 67 patients with MS complicated by mild PH (systolic pulmonary pressure <50 mm Hg, group M) in this study and we compared their immediate and late results after a follow-up period of 24 months after PBMV.

RESULTS

Compared with group M, patients in group S were older, presented more frequently with NYHA III-IV class, valvular echo score >or=8, and more severe tricuspid regurgitation, and had a bigger left atrial diameter before PBMV. The successful rate and the incidence of severe complications from the PBMV procedure were similar in both groups. There were more cases of post-PBMV mitral valve area >or=1.5 cm(2) in group M than in group S, and the average mitral valve area in group M was somewhat larger than that of group S. After PBMV, NYHA class obviously improved in both groups, but there were more patients with NYHA<or=class II in group M than in group S at discharge. During the 24-month follow-up, 7 patients (10.5%) in group M and 11 (25.0%) in group S developed cardiac events (p<0.1). Cumulative event-free survival was 89.6% in group M and 75.0% in group S (p>0.05). NYHA class I or II was present for 80.6% in group M and 59.1% in group S (p<0.10).

RESULTS

PBMV is a safe and effective procedure for patients with severe PH. It can remarkably improve clinical outcomes, although hemodynamic effects of PBMV on this subgroup are not complete. Pre-existing older age, more severe valvular lesion and tricuspid regurgitation, worse cardiac function, and bigger left atrial size in patients with severe PH may be important risk factors for the poor hemodynamic outcomes of PBMV.

Percutaneous Valve Replacement: Current State and Future Prospects

Percutaneous valve implantation is the development of a foldable heart valve that can be mounted on an expandable stent delivered percutaneously through standard catheter-based techniques and implanted within a diseased valve annulus. In cases with severe aortic stenosis, the diseased valve has to be pre-dilated. To perform a true replacement the diseased valve has to be ablated and removed. In this article, we review the development of percutaneous valve replacement technology and discuss future prospects in this field.

Effect of electrical stimulus parameters on the development and propagation of action potentials in short excitable fibres

Intracellular action potentials (IAPs) produced by short fibres in response to their electrical stimulation were analysed. IAPs were calculated on the basis of the Hodgkin-Huxley (1952) model by the method described by Joyner et al. (1978). Principal differences were found in processes of activation of short (semilength L less than 5 lambda) and long fibres under near-threshold stimulation. The shorter the fibre, the lower was the threshold value (Ithr). Dependence of the latency on the stimulus strength (Ist) was substantially non-linear and was affected by the fibre length. Both fibre length and stimulus strength influenced the IAP amplitude, the instantaneous propagation velocity (IPV) and the site of the first origin of the IAP (and, consequently, excitability of the short fibre membrane). With L less than or equal to 2 lambda and Ithr less than or equal to Ist less than or equal to 1.1Ithr, IPV could reach either very high values (so that all the fibre membrane fired practically simultaneously) or even negative values. The latter corresponded to the first origin of the propagated IAP, not at the site of stimulation but at the fibre termination or at a midpoint. The characters of all the above dependencies were unchanged irrespective of the manner of approaching threshold (variation of stimulus duration or its strength). Reasons for differences in processes of activation of short and long fibres are discussed in terms of electrical load and latency. Applications of the results to explain an increased jitter, velocity recovery function and velocity-diameter relationship are also discussed.