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a Department of Thoracic and Cardiovascular Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China
b Department of Echocardiography, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China
Accepted for publication March 25, 2008.
* Address correspondence to Dr An, Department of Thoracic and Cardiovascular Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, People's Republic of China (Email: anqi8890{at}163.com).
| Abstract |
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Methods: Thirty patients who had nonmuscular ventricular septal defects underwent perventricular closure by minimally invasive technique without cardiopulmonary bypass. A subxiphoid minimally invasive incision was performed. Under the continuous guidance of transesophageal echocardiography, the free wall of the right ventricle was punctured and a guidewire was introduced into the left ventricle through the defect. A delivery sheath was advanced over the wire and through the defect into the left ventricle. The device was released.
Results: Closure was successful in 27 patients (90%). There was no mortality or atrioventricular block perioperatively or during the entire follow-up period. Three patients developed incomplete right bundle branch blocks and seven patients developed new trace or mild tricuspid regurgitation after the closure. The mean hospital stay was 3.6 ± 0.7 days (range, 3 to 5 days) and no patient needed any blood or blood products. Follow-up at 6 months showed that two of the three patients had persistent incomplete right bundle branch block and three of the seven patients had persistent closure-related trace or mild tricuspid regurgitation.
Conclusions: Perventricular device closure of isolated ventricular septal defects without cardiopulmonary bypass appeared to be safe and efficacious in selected young children. The outcomes of short-term follow-up are acceptable.
| Introduction |
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| Patients and Methods |
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Devices
All the occluder devices (Shanghai Shape Memory Alloy Corporation, Shanghai, China) are made of 0.004-inch Nitinol wire mesh. The wires are shaped to form two discs, with a short connecting waist. The device is self-expandable and fully retrievable to the point of release. The size of the device corresponds to its waist. There are two categories of device; one is concentric and the other one is eccentric. The flanges of the concentric device are measured 2 mm around the waist, on both the right and left ventricular sides. In an eccentric device, the flange of the left ventricular disc, which faces the aortic valve, is only 0.5 mm or 0 mm larger than the waist, while the flange of the disc which is on the opposite side of the aortic valve is 5 mm larger than the waist. The right ventricular disc of the eccentric device is the same as the concentric device (ie, 2 mm larger than the waist all around). A female screw is welded in the center of the right disc for attachment to the delivery cable and a metallic marker is welded to the edge of the larger flange on the left, to indicate the direction opposite the aortic valve (Fig 1).
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Follow-Up
A TTE and an electrocardiogram were routinely performed on all the patients at discharge and at 6 months follow-up as part of the study protocol. All the TTEs were done and interpreted by the same echocardiographer with specific attention to any new aortic or tricuspid valve regurgitation and residual shunt. Arrhythmia (if any) would be recorded. The end-diastolic diameter of the LV was measured only at discharge.
Statistics
Data are expressed as mean ± SD. Paired data of the end-diastolic diameter of the LV were analyzed using a 2-tailed paired t test. Values for p less than 0.05 were considered significant. Statistical significance was tested using SPSS 13.0 (SPSS Inc, Chicago, IL).
| Results |
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In the 27 successful cases, two PVSDs, whose upper edges were 1-mm and 1.5-mm away from the aortic valves, respectively, were both successfully closed by 0.5-mm eccentric devices. Both subarterial VSDs and a PVSD were successfully closed by 0-mm eccentric devices. The rest of the PVSDs were all closed by concentric devices. The mean size of the devices was 7.7 ± 1.8 mm (range, 4 to 12 mm). None of the eight preexisting tricuspid regurgitations worsened after the closures; in fact, two of them diminished from mild to trace immediately after the closures of the PVSDs. On the other hand, 7 patients with PVSDs developed new trace or mild tricuspid regurgitations, and 3 patients developed incomplete right bundle branch blocks (IRBBB) after the procedures in the operating room (OR).
At discharge, no new valvular problems or arrhythmia were observed; in fact, two of the seven closure-related tricuspid regurgitations (trace) and one IRBBB were found to have disappeared. No aortic incompetence was found. The mean end-diastolic diameter of the LV of 27 patients was 28.7 ± 2.6 mm (range, 25 to 35 mm), which was significantly smaller than that before the procedure (p < 0.05). Follow-up at 6 months with TTE revealed that another closure-related and two preexisting tricuspid regurgitations diminished in magnitude (from mild to trace). The two closure-related IRBBB remained and no aortic incompetence was observed. No AVB or residual shunt was found during the entire follow-up period.
Except for a one-year-old boy, who was mechanically ventilated for 2 hours after the procedure, all the patients were extubated in the OR. No children needed any blood or blood product transfusion at any time. The mean hospital stay was 3.6 ± 0.7 days (range, 3 to 5 days).
| Comment |
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Compared with the conventional VSD repair, the unequivocal advantage of PVDC lies in the avoidance of CPB. The deleterious effects of CPB in pediatric patients, especially on brain development, have been well-documented [13, 14]. A more recent study [15] also showed that avoiding CPB in children might decrease postoperative morbidity and mortality. In addition, the PVDC requires a much shorter operating time and hospital stay. It also markedly reduces, if not eliminates altogether, the need for blood and blood product transfusion. In our series, we performed the PVDC through a subxiphoid minimally invasive incision, which allows the direct extension of the same incision to a full sternotomy in the event that conversion to CPB is needed.
Unlike muscular VSDs, the perimembranous and subarterial VSDs lie much closer to the conductive tissues and aortic valve; therefore, AVB and aortic incompetence are potential complications for PVDC. Similar to the results reported previously [9–11], there was no AVB in our series. This compares favorably with the reported incidence of complete AVB after transcatheter device closure of VSDs [6]. This might be due to the fact that during PVDC the sheath carrying the device approaches the plane of the defect at a more or less perpendicular angle; thus minimizing if not avoiding compression with subsequent trauma to the tricuspid annulus, where the atrioventricular node is located. Transcatheter device closure, on the other hand, necessitates the passage of the cable with the device through the tricuspid annulus to reach the defect; thus potential damage to the atrioventricular node. Three patients in our series developed IRBBB after PVDC. One possible reason might be the edema of the adjacent tissues caused by the friction between the tissue and the device. This may explain why one IRBBB disappeared at discharge without any treatment when the tissue edema may have subsided. The possible injury of the conductive tissues located at the inferoposterior aspect of the defect caused by the guidewire or the device itself might also be another reason. However, the incidence of arrhythmia in our series compared favorably with that reported by transcatheter treatment [16].
Amin and colleagues [10] concluded in their experiment that an eccentric device might have better success rate than a concentric device. In our study, however, all the concentric devices (22 of 22) completed the closures without any aortic insufficiency, whereas only five out of eight eccentric devices were deployed successfully. The concentric devices were used for all VSDs whose upper edges were more than 2 mm from the aortic valve. When the distance was between 1 and 2 mm, an eccentric device with a 0.5-mm flange on the aortic side was used, and a device without an edge (0 mm) on that side would be used if the distance was less than 1 mm. The success rates of these three different devices were 100%, 67%, and 60%, respectively. We feel strongly that the choice of the device used should be based on the distance between the upper edge of the defect and the aortic valve. The only residual shunt after deployment of an eccentric device occurred in a 0-mm device with which we attempted to close a relatively large defect (8.5 mm). We failed to close another two defects because of aortic insufficiencies; even eccentric devices (0 mm) were deployed. We speculate that there might be mild aortic prolapses that were not detected by the preprocedural TEE, and the regurgitations might be caused by the devices compressing on the already prolapsed aortic valve leaflets making them more incompetent. This would suggest that PVSDs or subarterial VSDs associated with even mild aortic prolapse should not be considered for PVDC. Otherwise, clinically significant aortic regurgitation might occur.
The occurrence of seven new tricuspid regurgitations after the closures of PVSDs did not seem to have any relationship with the presence or absence of septal aneurysms because only two out of the seven patients who developed new tricuspid regurgitations had septal aneurysms. Rather, the new tricuspid regurgitations might very well be caused by the newly deployed device, which might have distorted the subvalvular apparatus. Two preexisting tricuspid regurgitations diminished from mild to trace in the OR after PVDC. The possible explanation for this occurrence is that part of the regurgitant stream coming from the LV was immediately stopped after deployment of the device. At 6-month follow-up, one procedure-related and two preexisting tricuspid regurgitations further diminished in magnitude. This is most likely due to the fact that with successful PVDC the RV is no longer subjected to chronic volume overload. As the RV volume decreases with time, as documented by our follow-up TTE, so does the diameter of the dilated tricuspid annulus, rendering the tricuspid valve more competent.
In summary, the PVDC of isolated VSDs without CPB appeared to be safe and efficacious in a select group of young children, with acceptable short-term outcomes. However, further studies and long-term follow-up are necessary to evaluate the natural course of the closure-related tricuspid regurgitations and the long-term effect of the device on the left ventricular outflow tract and the aortic valve before PVDC can be recommended as an acceptable alternative to the treatment of isolated VSDs.
| Acknowledgments |
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| References |
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