J Thorac Cardiovasc Surg 1995;110:856-0859
© 1995 Mosby, Inc.
Transventricular mitral valve dilator: An improved design concept
Ajay Kaul, MCH,
Susmit Bhattacharya, MS,
Shirish Borker, MS,
A. M. Patwardhan, MS, MS,
A. P. Chaukar, MB, MS,
A. D. Abhyankar, MD, DM
Bombay, India
From L.T.M.M. College and L.T.M.G. Hospital, Sion, Bombay, India.
The concept of dilatation of stenotic valves was first put forward by Samways in 1898. The Tubbs Logan dilator (M/s All India Surgical Manufacturing Co., Bombay, India) came into use in the 1950s to allow the surgeon to treat rheumatic mitral stenosis much more easily.
The advent of sophisticated catheterization laboratory techniques and the development of a percutaneous balloon mitral valve dilator minimized the surgical trauma of treatment of mitral stenosis. The balloon mitral valve dilator, whether of the Inoue (Toray Industries, Inc., Tokyo, Japan) or Mansfield type, is an adequate mitral valve dilator as shown by several authors.
1-5 A study by Pateland associates 6 concluded that the balloon was a superior dilator compared with the Tubbs dilator, whereas another study showed similar results with both. 7
In our hospital percutaneous balloon mitral valvuloplasty and transventricular closed mitral valvotomy are performed regularly. We have observed that the gradients across the mitral valve fall to 3 to 5 mm Hg after balloon dilatation but remain between 7 and 10 mm Hg after a Tubbs dilatation. However, these values occurred in different sets of patients under different conditions and it was difficult to arrive at a conclusion regarding efficacy of each of the dilators.
We therefore wanted to do a comparative study in the same set of patients under the same conditions. We introduced the Inoue balloon dilator through the transventricular route and positioned the balloon across the mitral valve with a finger in the left atrium exactly as we do with the Tubbs dilator. Inflation was done by an assistant.
Twelve patients with mitral stenosis were chosen at random (Table I). The echocardiographic findings in these patients are summarized in Table II. They were divided into two groups. In group I (n = 5), valves were first dilated with a balloon introduced through the left ventricle. After complete dilatation we tried using a Tubbs dilator to see whether there were any changes. In group II (n = 7) the sequence was reversed. The maximum dilatation by a Tubbs dilator was assessed on the operating table by palpation of the valve as is routinely done. The maximum dilatation of the balloon was done according to the height of the patient, as specified. The adequacy of release of the mitral valve was assessed by finger palpation of the mitral valve apparatus and by simultaneous pressure recordings of the left atrium and the left ventricle. The end-diastolic gradient across the mitral valve was calculated from recordings of mean left atrial pressure (LAP) and left ventricular end-diastolic pressure (LVEDP).
The results are summarized in Table III and IV. The data were subjected to paired t test. There was no significant difference between the two groups with reference to predilatation LVEDP, LAP, or the predilatation gradient (LAP-LVEDP). Hence we compared the residual gradient after Tubbs dilatation (group II) and balloon dilatation (group I). The residual gradient after Tubbs dilatation (group II) was significantly higher than that after balloon dilatation (group I). It also follows that balloon dilatation after Tubbs dilatation (group II) significantly reduced the residual gradient, whereas Tubbs dilatation after balloon dilatation (group I) did not significantly reduce the gradient. Representative pressure tracings from the two groups are shown in Figs. 1 and 2.
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Fig. 1.A, Pressure recordings before mitral valve dilatation. B, Pressure recordings after balloon dilatation of mitral valve. LVP, Left ventricular pressure.
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On finger palpation, the mitral valve apparatus was extremely well opened after balloon dilatation in terms of commissural and subvalvular release (group I). Subsequent Tubbs dilatation did not improve the results. The commissural and subvalvular release were also thought to be better after the subsequent balloon dilatation (group II). However, this is a subjective evaluation.
This study has led us to believe that the balloon with its circumferential dilatation and radial stretching capabilities might be a better valve dilator. On the basis of this hypothesis we have been trying to manufacture a transventricular balloon dilator. The work is still in its infancy but initial trials have encouraged us to move forward. We hope to publish more data in the future.
Acknowledgments
We acknowledge the assistance of David C. Naftel, PhD, Department of Surgery, Division of Cardiothoracic Surgery, University of Alabama, Birmingham.
Footnotes
J THORAC CARDIOVASC SURG 1995;110:856-9 
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