Discussion
Since the classification of Rastelli, CAVSD is a congenital anomaly, the anatomy of which is well known and operated with very successful outcomes with the contribution of developing technology and surgical techniques. Coexisting additional anomalies do not affect the outcomes with low morbidity and mortality. Andrew et al. stated that there was no difference between a single patch or a two-patch in terms of residual lesion or valve regurgitation in trisomy 21 cases.12İxe et al. reported the optimal surgical time as 3-6 months in among their patients to who have been operated 92% by TPT and 2.2% the single-patch technique. Besides they have observed that Down syndrome was not a risk factor for reoperation.13 On the other hand, Tumanyan at al compared 214 patients with only CAVSD to 163 patients with concomitant Down syndrome. They have applied the TPT to 75.4% and the single-patch technique to 24.6%. Although the researcher could not find a difference in terms of the repair technique, he stated that the additional morbidity of Down syndrome patients compared to patients without this accompanying disorder, affected the recovery period and life expectancy.14 In our cases, as can be seen from the table, the coexistence of additional cardiac anomalies and Down syndrome (65%) is quite common. However, like other anomalies, trisomy 21 did not cause additional morbidity and mortality, which revealed statistical significance.
CAVSD malformations are patients with AV junction defect and a common single complete AV valve.15-16 In CAVSD, the increased flow due to a large defect may increase pulmonary pressure very early.1 This does not cause problems due to high pulmonary resistance in the first 3 months. Full correction surgery in the early period prevents pulmonary vascular disease. In this sense, CAVSD repair should be performed in an average of 4 months. Bakhtiari and Rudid Takacs reported an operation time in the 3.8 months on average in their series.17 In our series, the fact that there were 23(%41) patients who have right ventricle outflow truct stenosis and pulmonary banding due to additional anomalies. Mean and median age of these patients are 17 and 33 months respectively. Nevertheless, almost all of our patients came from abroad and from regions where early diagnosis-treatment remained insufficient caused the our median operation timing to be the 7,5 months in MSP and the 14 months in TPT, and the mean average was the 9 months. However, there were no serious problems related to pulmonary hypertension, and just 4 of 6 patients who had undergone pulmonary banding before required NO2inhalation.
Transthoracic echocardiography or even perinatal echocardiography is sufficient for diagnosis. Cohen GA reported that intraoperative transesophageal echocardiography (TEE) would be highly an instructive guiding and beneficial examination during CAVSD repair as in all congenital heart disease surgeries.18 Approximately 35% of our cases were performed under guidance of intraoperative TEE. Cardiac catheterization, magnetic resonance imaging, and computerized tomography should be performed at an advanced age to measure pulmonary pressure reversibility or if evaluation for additional anomaly is required.
The MSP has been used more frequently in the last decade, in addition to the conventional single-patch and TPT that have been used in the past.8
In this retrospective study, 66% of the cases were operated with MSP technique, while 34% were operated with the TPT. The conventional single-patch technique was not preferred in our center like in many centers. In our series, the VSD diameter was found to be smaller and ACC and CPB times were found to be shorter in the MSP technique. Li et al. compared the MSP and TPT in terms of many parameters (VSD diameter, CPB-ACC time, mortality, reoperation). As in our series, the VSD diameter was smaller and the CBP and ACC times were shorter in MSP, and there was no significant difference in other parameters.(19) Jeong IS and Pan G found only CPB and ACC time and hence ischemia time shorter in the use of a modified single patch, while they found other parameters to be similar.20-21
In the study, short CPB and ACC time did not create a significant difference in the intubation time, duration of intensive care and hospitalization, in accordance with the literature. Moreover, the amount of drainage was significantly higher in TPT, but there was no significant difference in the use of blood products. This is also compatible with our institutional policy that we use restricted blood-blood products for drainages not causing clinical and hemodynamic deteriotaion.22
The late outcomes of the both tecniques were analysed in the literature, there was no statistically significant difference.23The most important factor affecting the late period outcomes is the incidence of reoperations. Ginde S et al. followed 198 patients for an average of 17.2 years and found LAVV regurgitation as the most common cause of reoperation. In this series, the 30-year no-reoperation rate is 78%, while the 10-year rate is 88%.24 Prifti and Massimo stated that left LAVV malfunctions during the primary repair of CAVSD were important risk factor for reoperations.25In our study where we compared TPT and MSP, performed mostly, moderate-severe LAVV regurgitation was observed statistically significantly less in the MSP group in the postoperative early and middle period. The reduced three-dimensional calculations in the MSP technique, the number of patches and the easy applicability of the technique cause this result. Graham Nunn reported 1.6% mortality and 2.3% residual VSD in 128 patients in whom he applied MSP in his series, while he did not report valve regurgitation in these patients. In the mean time he observed late-stage LAVV regurgitation to be 0% and LVOTO to be 2.3% in 46 patients to whom he applied a two-patch.8 LVOTO was not observed in any of our groups.
When the two techniques are compared conventionally, reoperation rates emerge as the most important difference. LVOTO is not observed in the MSP, whereas reoperation rates can increase up to 15% due to LVOTO in the TPT. Mortality rates are 1.2% in the MSP and 3.5% in the TPT. Reoperation rates due to the AV valve are 2.2% and 7.2%, and pacemaker rates are 0.4% and 1.9%, respectively.26-27 In our series, while there was no difference in terms of mortality and pacemaker implantation, our overall pacemaker average was observed to be above the average indicated in the literature (4%). While the AV block risk was 2-2.5% in general in the TPT, it is between 0-1% in many series in which the MSP is applied.26
The most common cause of reoperation after additional AV valve repair is recurrent LAVV regurgitation (9-17%).28-29 However, as can be seen from the above-mentioned rates, the reoperation rates (2.2%) are quite low in the MSP. Some studies have stated that the most important cause of left ventricular AV valve regurgitation is annular dilatation, which is related to the operation timing.30-31 In addition to its ease to perform between 2-4 months, reduces reoperation rates. Delayed surgical timing and LAVV insufficiency are regarded as important risk factors for reoperation.13 Although LAVV insuffiency as a cause of reoparation was more frequent in our series, both could not be identified as a risk factors in our study. However, this result may have been obtained with the positive effect of the MSP technique applied at a high rate of 66% on LAVV insufficiency in our series. Alhough our patients operation timing was later that the recommended time in the literature, no difference was found in long terms of reoperation and mortality when the two techniques were compared.
The most significant advantage of the MSP technique is eliminating complications that may occur due to the dimensions of this patch by not placing a VSD patch. The non-splitting of the valve prevents tissue loss from the valves, thus eliminating another technical cause that may contribute to AV valve regurgitation. The mortality in reoperations due to left AV valve residual defect and other reoperation causes is about 9.8%.26 The rate of LVOTO is usually 4.2%. While Geoffrion et al. presented this rate as 0.6% in their series, the rate was reported to be 0 % in Nunn’s series in the MSP technique.26-27
In conclusion, when the modified single-patch technique is compared with the two-patch technique in this series, the CPB-ACC time is shorter in favor of MSP, the VSD is smaller in accordance with the nature of the technique, LAVV regurgitation is less, and, accordingly, the risk of AV valve reoperation is lower. Therefore MSP technique may be prefeferred in patients with suitable VSD diameter and localization in CAVSD.