Brain magnetic resonance imaging before and after percutaneous mitral balloon commissurotomy

Brain "embolism" detected by magnetic resonance imaging during percutaneous mitral balloon commissurotomy

PURPOSE

The common finding of thrombi between the bifoil balloons when they were extracted after mitral dilation prompted us to look for evidence of minor brain embolisms using the sensitive technique of BMRI (brain magnetic resonance T2-weighted imaging).

METHODS

BMRI was performed within 48 hr before and after a percutaneous mitral balloon commissurotomy (PMBC) in each of the 63 patients in this study.

RESULTS

There was evidence (hyperintensity foci: HI) of a previous asymptomatic brain embolism in 38 of 63 patients before PMBC and a new HI appeared in 18 of 63 patients after the procedure. New HI signals were found exclusively in the white matter in 8 of 18 patients and in only 3 of 18 were HI signs larger than 1 cm. One patient, with an HI signal > 1 cm in the thalamus and another < 1 cm in the brain stem, presented diplopia accompanied by other minor clinical signs. The differences in HI rate among four subgroups (1, older vs younger than 43 years; 2, sinus rhythm vs atrial fibrillation; 3, echo score < 8 vs > 8; 4, patients from western countries vs the others) were not statistically significant, probably because the number of patients in each subgroup was low. Patients in atrial fibrillation had slightly more (not significant) HI before PMBC (15/20, 75%) than patients in sinus rhythm (23/43, 53%), but after PMBC their HI frequencies were similar (atrial fibrillation: 5/20, 25%; sinus rhythm: 13/43, 30%).

CONCLUSION

Brain microembolism is frequent during PMBC, but is often anatomically limited and free from clinical signs in most cases. Brain embolism seems to be related mainly to the procedure itself and not the features of the patient.

Balloon valvuloplasty for mitral stenosis

Balloon mitral valvuloplasty (BMV) for mitral stenosis is a procedure that has evolved significantly since its introduction by Inoue et al. in 1984. This article reviews currently used techniques, advantages, and limitations as well as outcomes in comparison with surgical procedures. Included is a review of imaging techniques that facilitate BMV, such as transesophageal echocardiography and the recently developed tri-dimensional transthoracic echocardiography and intracardiac echocardiography. In a separate section, the application of BMV in specific clinical situations, such as in patients with multivalvular disease, during pregnancy, in children, in the presence of thrombi, and in patients with bioprostheses, is discussed.

Contrast echoes detected during percutaneous mitral balloon commissurotomy with Inoue balloons and their relation to cerebral microembolic signals

The aim of this study was to find out the mechanism of genesis of contrast echoes detected with echocardiography during percutaneous mitral balloon commissurotomy (PMBC) procedures with Inoue balloons and to assess their association with cerebral microembolic signals with transcranial Doppler examinations. Ten Inoue balloons (Toray Instruments) were used in 10 patients (mean age 36 +/- 10 years). In all patients transesophageal echocardiographies with a multiplane 5 MHz probe were performed immediately before and during the PMBC procedure. None of the patients had left atrial thrombus during the PMBC. All of the balloons were inflated within the left atriums and left ventricles and were tested in saline to see whether there was a visible air leak after the PMBC procedures. Transcranial Doppler examinations were done with 2 MHz probes from the middle cerebral artery. Contrast echoes were detected in all patients during inflation and/or deflation, independent of the intracardiac sites. After a few cardiac cycles there was a very intense shower of microembolic signals detected with the transcranial Doppler examination, which persisted for all inflations and/or deflations. All balloons yielded visible air leaks from the two small holes at the waist of the balloons in saline. There were a few contrast echoes recorded in some of the patients during the exchange of equipment, and one patient had a transient neurologic and coronary ischemic event following the introduction of the stretcher tube of the Inoue balloon. Intracardiac contrast echoes and transcranial microembolic signals during the PMBC procedure were detected in all PMBC procedures and were due to air that was entrapped between the two latex layers of the Inoue balloons and air introduced from outside during the exchange of the equipment.

Rapid onset and dissipation of left atrial spontaneous echo contrast during percutaneous balloon mitral valvotomy

BACKGROUND

Thromboembolism after percutaneous balloon mitral valvotomy (PBMV) has been attributed to dislodement of preexisting thrombus during transseptal puncture and instrumentation of the left atrium. The occurrence of thromboembolic events after PBMV in the absence of demonstrable left atrial thrombus before PBMV suggests that thrombus might form during the procedure. Spontaneous echo contrast (SEC) is a swirling pattern of blood echogenicity that is a marker of blood stasis in the left atrium. Exacerbation of left atrial SEC during PBMV may be indicative of an increased thromboembolic risk.

METHODS

Transesophageal echocardiography was performed during PBMV in 20 patients with mitral stenosis. Grades of severity of left atrial SEC [0 (nil) to 4+ (severe)] were allocated before and after each balloon inflation.

RESULTS

Before PBMV, SEC was present in 17 patients. New SEC or increased severity of SEC was observed during 49 of 56 balloon inflations. SEC was unchanged after six deflations, decreased after 14 deflations, and disappeared after 36 deflations. The mean times to onset and dissipation of SEC after balloon inflation and deflation were 3.1+/-1.5 and 3.9+/-1.6 seconds, respectively. After successful PBMV, SEC was unchanged in three patients, decreased in one, and resolved in 13.

CONCLUSIONS

SEC is a dynamic and acutely reversible phenomenon that is highly sensitive to changes in left atrial hemodynamic conditions. Left atrial blood stasis induced by balloon inflation may promote thrombogenesis during PBMV.

Percutaneous balloon mitral valvuloplasty

Percutaneous balloon mitral valvuloplasty, first performed by Inoue in 1982, was a rational progression from 4 decades of experience with the blunt surgical dilatation technique of closed mitral commissurotomy. As with surgical commissurotomy, balloon valvuloplasty relieves mitral stenosis by the splitting of fused commissures. A series of studies have shown that balloon valvuloplasty achieves excellent acute hemodynamic results in close to 90% of patients, with a typical 100% increase in mitral valve area. Over the past 15 years since Inoue's first patient, a number of other techniques have been introduced and largely discarded in favor of the original approach. Advances have occurred along the lines of improved noninvasive assessment of mitral valve disease, which have allowed better case selection and prediction of outcome. Follow-up series have shown sustained improvement, with modest rates of complications and restenosis. Comparative studies have shown that balloon valvuloplasty is as effective and safe as surgical commissurotomy, and is a cost-effective procedure of first choice in ideal patients.