Page 21 - Journal of Structural Heart Disease Volume 5, Issue 6

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Original Scientific Article
When using the retrograde approach, the right disc has to be completely open on the right side of the VSD so when it is pulled gently towards the left side, the full occlusion of the right orifice is performed. Later on, the waist and left disc are deployed within the aneurysm, with no differences regarding residual shunt between both approaches.
The patent foramen ovale (PFO) allows reaching through the mitral valve, the left ventricle and cathe- terizing mid-ventricular and apical VSDs from the cav- ity. Caution must be placed during the procedure in order to avoid injuries to the mitral valve. The guides must be covered with the catheter at all times and the placement of the sheath through the mitral valve must be done carefully.
Smaller devices contain compact mesh, compare to the larger ones. The PTFE membrane is needed in- side the larger occluders to facilitate the closure.
The MFO devices come in different sizes, where the greater diameter of the waist goes from 5 to 14mm and the disc from 10 to 18 mm, enabling the closure of VSDs from 3 mm to 12 mm. To select the adequate device size, the Company suggests that the right waist should exceed the maximum right diameter of the VSD by at least 2 mm. Occasionally the right disc, contributes to the occlusion avoiding the oversize of the device.
In our analysis, the cohort of patients showed that when comparing the right waist of the device with the echocardiographic measurement of the right ori- fice of the VSD, the mean of the diameters was almost equal. The same result was showed when comparing the left waist of the device with the left diameter of the defect. The result of the analysis of the cohort of patients showed, that the size of the discs had a signif- icant difference with the left waist, which established a linear relationship between the left diameter of the VSD and the size of the discs. The discs device was 4 mm larger than the left orifice of the VSD, concluding that the required size of the disc using the diameter of the left orifice of the VSD should have an additional 4 mm.
Another relevant observation during the analysis for the closure of the perimembranous defects was that the size of the device was ruled by the diameter of the aneurysm, as it had to be placed inside to avoid
the AV block, to perform the complete occlusion of the right orifices, sometimes more than one.
The perimembranous VSDs without aneurysm is difficult to be treated with MFO [15-19] since the symmetrical discs might injure the Aortic sigmoids. Eccentric devices can be used for these types of de- fects where the left disc does not reach the aortic sig- moid valve [22].
Base on our experience, the alternative treatment was able to be offered to patients with very low weight, greater than 2,500 kg [7, 26-28], serious life risk, and did not comply with any requirement need- ed for other treatments. This group of patients mani- fests heart failure and acute pulmonary edema due to large defects, greater than 5 mm. Babies with a severe left to right shunt are often symptomatic with failure to thrive and can die from heart failure and respira- tory compromise if the medical treatment is insuffi- cient and the closure is delayed. Only patients with mid-ventricular and apical VSD can benefit from MFO for endovascular closure. Patients with high muscu- lar and perimembranous VSDs, especially in patients under 1 year of age, will not be recommended for clo- sure due to the high risk for complete AV block [12]. The low-profile and flexibility of the delivery system is well tolerated by the venous system that allows the crossing through the foramen ovale to LV avoiding the puncture of the arterial, common complication in young children. This is the main reason why Nag- eswara [26] and Zartner [27] already proposed avoid- ing arterial puncture in young children.
The postoperative residual VSDs range has been reported between 5 and 25% [30] if reoperation is decided, complications can arise [31]. When residual VSDs are greater than 3 mm and associated with QP / QS over 1.5 / 1, they need to be closed [32, 33]. Base on the information mention before, the endovascu- lar treatment is a suitable option. In our experience, two patients had a residual postoperative VSD and re- quired endovascular closure with no complications in the follow-up. Both patients had post-surgical com- plete right bundle branch block, so they underwent Holter prior to the procedure that did not show any other type of severe arrhythmia that contraindicated the device occlusion, and they did not present com- plete AV block during follow-up.
Damsky Barbosa J. et al.
VSD Closure with KONAR-MFO