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ORIGINAL ARTICLE
Year : 2022 | Volume
: 11
| Issue : 3 | Page : 59-65
Evaluation of aortic root dilation in adult patients after repair of tetralogy of Fallot
Mozhgan Parsaee1, Atieh Rezaeefar1, Zahra Khajali2, Hamideh Khesali1, Mohammad Bidkhori3, Abbas Soleimani4
1 Echocardiography Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
2 Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
3 Department of Epidemiology and Biostatics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
4 Department of Cardiology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran
Correspondence Address:
Dr. Atieh Rezaeefar
Echocardiography Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran
Iran
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/rcm.rcm_3_22
Background and Aim: Aortic root dilation is one of the common complications in patients with a history of tetralogy of Fallot total correction (TFTC). We evaluate the frequency of aortic root dilation in adult TFTC patients and analyze probable risk factors related to the dilated aortic root. Materials and Methods and Results: We reviewed echocardiography images of 146 adult TFTC patients who admitted at Rajaie Cardiovascular Medical and Research Center from 1383 to 1399 in an observational retrospective cohort study. Sinus of Valsalva (SOV) was measured in parasternal long-axis view. Aortic root dilation was determined by two definitions. When we adjusted SOV diameter for body surface area and sex, the frequency of aortic root dilation was 68%, with a mean SOV diameter of 3.5 ± 0.7 cm and when we used absolute diameter ≥4 cm for dilated SOV, 22% showed aortic root dilation. By multivariate logistic regression analysis, male sex (odds ratio (OR) = 3.47, P = 0.003), age at the time of TFTC (OR = 1.06, P = 0.009), and aortic regurgitation (OR = 3.97, P = 0.003) were associated with increased adds of dilated aortic root. Three patients underwent aortic surgery, including one case of type A aortic dissection. Conclusion: Although aortic root dilation was common, aneurysmal dilation and adverse events were not so frequent. Serial evaluation of all segments of the ascending aorta, including the aortic root, is important but not more frequent than previously suggested.
Keywords: Aortic dilation, aortic dissection, congenital heart disease, tetralogy of Fallot
Tetralogy of Fallot was recognized by these criteria:[1] nonrestrictive ventricular septal defect (VSD), obstruction at right ventricular outflow tract, overriding aorta, and right ventricle hypertrophy. Today, tetralogy of Fallot total correction (TFTC) is commonly done with acceptable surgical risk, and many of them reach adulthood.[2]
Aortic root dilation has been frequently observed in patients with TFTC, but little information about the aorta is available in these patients. Until now, there has not been any study on aortic enlargement in TFTC patients admitted to Rajaie hospital, so we decided to do research on these patients and evaluated the aortic root in adult TFTC patients.
Materials and MethodsWe prepared a list from all the adult patients (≥17 years old) admitted to Rajaie Cardiovascular Medical and Research Center with TFTC diagnosis from 1383 to Aban of 1399. It contained 475 patients. However due to limited time, we could only review the medical records and echocardiography data of 238 of them. We chose these patients from the top and bottom of the list alternatively, and assessed them in an observational retrospective cohort study. The study was approved by the ethical committee of Rajaie Cardiovascular Medical and Research Center (IR. RHC. REC.1400.012).
Patients with a diagnosis of Tetralogy of Fallot (TOF) who underwent total correction repair and had at least one transthoracic echocardiography (TTE), which was done after TFTC and when the patient was 17 years old or more, were eligible to include to the study. If echocardiography images were not available at PACS system or not suitable for aortic root sizing in accordance with American Society of Echocardiography (ASE) recommendations,[3] we exclude it from the study.
Hence, from the 238 patients, we reviewed their medical records, 92 patients could not achieve eligibility to enter the study. Thirty-six patients had no any echocardiography imaging data, 53 patients had no suitable echocardiography imaging for aortic sizing, and three patients underwent aortic valve surgery before 17 years old. At last, 146 patients entered the final analysis.
For each patient, the most complete echocardiography report with suitable echocardiography images in the PACS system was chosen. The size of sinus of Valsalva (SOV) was measured in the parasternal long-axis view from leading edge to leading edge. As all these images were not saved at the end of diastole (Peak QRS) so, the measurement was done regardless to the systolic or diastolic time. The maximal diameter of the SOV was measured. Aortic regurgitation (AR) and its severity (graded as trivial, mild, mild to moderate, moderate, moderate to severe, and severe) and residual VSD were obtained from the echocardiography report. We used normative data by Roman et al.[4] as the reference to define aortic root dilation, so the SOV diameter was indexed to the body surface area.
Statistical analysis
Categorical variables were presented with frequencies and percentages, and comparison was made by Chi-square test. Continuous data were summarized as mean ± standard deviation and comparing were performed using the Independent Samples t-test. Predictors of aortic root dilation were assessed in univariate and multivariate logistic regression models. All reported P values are two-sided and P < 0.05 was considered statistically significant. Analysis was performed using IBM SPSS Statistics for windows, version 24.0. Armonk, NY: IBM Corp. NY, USA.
ResultsWe retrospectively studied 146 TFTC patients with 87 (59.6%) males. The mean age at the time of echocardiography was 22.91 ± 7.11 years. 47 (32.2%) of patients underwent palliative shunt surgery at the mean age of 3.39 ± 3.37 years.
Patient characteristics according to aortic root dilation status based on Roman et al.'s reference,[4] adjusted for age and BSA, are presented in [Table 1].
Table 1: Patients' characteristics according to aortic root dilation based on Roman et al. referenceUsing this definition, aortic root dilation was present in 99 (67.8%) patients with a mean SOV diameter of 3.53 ± 0.77 cm. Patients with dilated root were older at the time of TTE and more likely to be male. They were older at TFTC time and aortic valve regurgitation was more common in this group. We could find the interventricular septal defect (VSD) size before TFTC at the pre-pump intraoperative transesophageal echocardiography report in 82 patients. Patients with dilated aortic root had larger primary VSD before corrective surgery.
The prevalence of aortic root dilation differed based on the definition used. When we used absolute diameter ≥ 4 cm for dilated SOV, 32 (21.91%) patients showed dilated aortic root with mean SOV diameter 4.48 ± 1.04 cm, and mean indexed SOV by BSA 2.60 ± 0.58 cm/m2[Table 2]. By this definition, besides the variables such as older age at the time of TTE and at TFTC time, larger primary VSD size, being male and aortic valve regurgitation, which showed significant P value according to the previous definition, longer duration of the palliative shunt (time between shunt surgery and corrective surgery), residual VSD and more than mild AR were more common in dilated root group (based an absolute diameter) with statistically meaningful value (P < 0.05).
Four patients had aneurismal SOV dilation (1.5 times more than the upper limit of the normal range), with a mean SOV diameter of 6.11 ± 2.63 cm [Table 3]. These patients with aneurysmal SOV trended toward higher pulmonary atresia (P = 0.20).
Variables associated with aortic root dilation based on both definitions are demonstrated in [Table 4], [Table 5], [Table 6]. Male sex and age at the time of TFTC are independently associated with dilated aortic root by both definitions. AR only showed a significant multivariate association with aortic dilation defined by Roman et al.'s references.[4]
Table 4: Variables associated with aortic root dilation in univariate analysis
Table 5: Variables associated with aortic root dilation (based on Roman et al. reference) in multivariate analysis
Table 6: Variables associated with aortic root dilation (sinus of Valsalva ≥4 cm) in multivariate analysisIn 238 medical records, we studied first, 6 (2.5%) patients underwent aortic surgical intervention that include aortic valve replacement in three patients, aortic valve repair combined with reduction ascending aortoplasty in one patient and aortic root replacement in another patient. We also had one case of type A aortic dissection, who underwent Bentall surgery [Table 7]. Two patients (33%) died in hospital before discharge (patients number 5 and 6) and the rest four patients discharged in good condition.
DiscussionAlthough in patients with TFTC, the right heart pathology is dominant, aortic dilation is commonly found. The prevalence of dilated aortic root in TFTC patients varies significantly in the literature, mostly because of different definitions used for dilated aorta in different studies. In our study, aortic root dilation is common in TFTC patients in adulthood, we showed a prevalence of 68% for aortic root dilation when we used Roman et al.'s reference[4] This finding is similar to the results of two studies, in which the definition of dilated aorta was the same as ours.[5],[6] we also used an absolute threshold of 4 cm to define dilated aortic root. Based on this definition, 22% of adult TFTC patients in our study showed dilated aortic roots. We found SOV diameter ≥4.5 cm in 4.7% and ≥5 cm in 1.3% of our patients. This prevalence is near to the findings of a study which showed 28.9% of their adult TFTC patients had aortic root diameter ≥4 cm[7] and the other study with a prevalence of 39% for SOV ≥4 cm in their adults TFTC patients.[2]
As some guidelines use absolute aortic diameter in their recommendations, this definition can have practical advantages. For example, according to the American College of Cardiology/American Heart Association thoracic aorta guideline,[8] annual aortic imaging study is reasonable in all patients with aortic diameter between 3.5 and 4.4 cm and every 6 months for patients with aortic diameter of 4.5–5.4 cm, noting there is some exceptions in patients with bicuspid aortic valve or other genetically mediated disorders. Although the risk of dissection is low in patients with aortic diameter <4 cm, 40% of patients with the diagnosis of dissection had aortic diameter <5 cm.[9]
In our study, AR was seen in 76% of the patients and the prevalence of more than mild AR was 22%. Eight percent of patients had moderate or more AR. The prevalence of significant AR in two studies on TFTC patients is similar to ours. In one study, moderate or more AR was seen in 3.5% of their patients[7] and in the other study,[2] 8% of patients showed moderate or more AR. Some mechanisms were described for aortic valve regurgitation in TFTC patients. The most important one is aortic enlargement, the other causes are aortic cusps distortion due to turbulent blood flow of overriding aorta, injury to the aortic valve during VSD repair or even fibrosis of the VSD patch itself can make injury on the aortic valve and cause AR.[10]
Although aortic dilation and aortic valve regurgitation are common in TFTC patients, aortic intervention is infrequently done on them.
For example, in one study, only 3% of patients underwent aortic surgeries,[2] or the other study showed only 15 aortic surgical interventions were done on 453 adult TFTC patients.[6] In our study, surgical aortic interventions were done on six patients (2.5%), but only three of them were in adulthood at the time of aortic surgery [Table 7]. Among these six patients who finally underwent aortic surgery, two patients died before discharge. In general, aortic operations in TFTC patients are not risk-free. In one multi-center study during 42 years, only 0.5% of TFTC patients underwent aortic surgeries, including surgery on the aortic valve, aortic root, and ascending aorta,[10] but 14% of them died early after aortic operations. They found ascending aorta dilation is related to higher mortality.
We had one case of aortic dissection type A among our patients. It was actually an incidental finding in a TFTC patient with no symptoms during routine follow-up. Except one study on 18353 TFTC patients that reported ascending aorta dissection was seen at 0.06% of their patients,[11] till now, in the other studies on TFTC patients, we could not find any prevalence of aortic dissection in this group of patients and only aortic dissection was reported in five TFTC patients as case reports.[12],[13],[14],[15],[16]
According to the rarity of aortic dissection in TFTC patients comparing to the other aortopathies such as bicuspid aortic valve, Marfan disease, Ehler's-Danlos and Loeys–Dietz syndrome[17] and high surgical risk of aortic operation in TFTC patients, determining a clear guideline for approaching to aortic dilation in these patients seems to be necessary. Utilizing bicuspid aortic valve or degenerative aortopathies guidelines for TFTC people can cause overtreatment in these patients, and although aortic interventions may be done with low surgical risk in high experience centers, these surgeries in TFTC patients with a history of multiple sternotomies can be problematic and also it must be noted that TFTC patients may need further surgeries in future too.
In patients with aortopathies associated with connective tissues disorders, when the aorta diameter reaches to more than 5 cm, risk of dissection or rupture increases.[18] Although there is no defined threshold for aortic surgery in TFTC patients, in the absence of a family history of aortic dissection or aortic aneurysm, aortic growth rate more than 1 cm per year and progressive AR (more than mild), some experts recommend that it can be possible to delay surgery till the aorta exceeds 5.5 cm.[1],[12]
Another important question in TFTC patients which has not been addressed yet is decision making for prophylactic aortic surgery at the time of surgical pulmonic valve replacement to avoid one additional open-heart surgery in future. Some factors such as the family history of aortic dissection or patient body surface area might be helpful in surgical planning.
On the other side, missing the patients at high risk for aortic dissection would be catastrophic, so optimal management of aortic dilation in TFTC patients is very important. Today, in contrast to many available information and recommendations about right heart pathologies in TFTC patients, there is little evidence-based information for managing aortic dilation in these patients.
As our study was a retrospective cohort and all levels of ascending aorta were not measured in each echocardiography study, and lack of suitable images with acceptable quality for measurement of ascending aorta in many patients, finally we decided to measure only SOV, so we did not have any information about the other segments of ascending aorta.
In the other studies,[2] it was shown that in some patients' aortic dilation may be happened only at ascending aorta with no evidence of dilation in the aortic root, so evaluation of the entire aorta is mandatory.
Considering the guidelines of aortopathies,[8],[19] it is logical to evaluate all segments of the ascending aorta, including the aortic root on a yearly basis in TFTC patients with a progressive increase in aortic diameter.
Several risk factors were considered for aortic dilation in TFTC patients in the literature.[5],[6],[7],[20] Some of these risk factors include male sex, right aortic arch, history of palliative shunt, pulmonary atresia, older age at the time of TFTC, residual VSD, and aortic valve regurgitation. Our multivariate analysis showed male sex, age at the time of TFTC and AR were independently associated with the dilated aortic root. Residual VSD and longer time from the palliative shunt to correction has a significant association with SOV ≥4 cm in univariate analysis (P = 0.04 and 0.02, respectively). When the analysis was performed by independent sample t-test, primary VSD size was significantly larger in dilated aortic root group than normal size group with P < 0.05.
Only in patients with aneurysmal SOV, we noticed a trend toward a higher prevalence of pulmonary atresia (P = 0.2).
In the study of Mongeon et al.,[7] male sex was the only independent factor associated with aortic root dilation. Pulmonary atresia and moderate or severe AR showed association with dilated aorta based on observed to expected aortic root dimension >1.5 in univariate analysis.
In Nagy et al.'s study,[2] pulmonary atresia, residual VSD, and AR were associated with dilated aortic root by multivariate logistic regression analysis, however the authors were uncertain about the clinical significance of pulmonary atresia because none of the patients underwent aortic surgery had pulmonary atresia.
There are two main hypotheses for aortic dilation in TFTC patients. The first is chronic right to left shunt from infancy to complete TOF repair, which causes overflow and hemodynamic stress on the aorta and finally aortic dilation. Many variables such as older age at the time of TFTC, residual VSD, history of palliative shunts, longer duration of shunt (time between palliative shunt surgery and corrective surgery) and AR are considered to cause aortic dilation at least theoretically by this way.[20],[21] The other hypothesis is that TOF patients may have an aortopathy by itself. Histologic abnormalities such as fragmentation of elastic lamella, medionecrosis, muscle disarray and fibrosis were seen in a significant percent of TFTC patients even at infancy.[22],[23],[24]
Considering the first hypothesis based on the volume overload effect on the aortic size, we expect patients with pulmonary atresia showed larger aortic size, but our results did not show any significant association between pulmonary atresia and dilated aorta. Although in patients with aneurysmal SOV, there was a trend toward a higher frequency of pulmonary atresia, it must be mentioned that the analysis was limited by the low prevalence of aneurysmal SOV in our study. Age at the time of TFTC was an independent risk factor in our study. Being older at TFTC time and longer duration between shunt operation and TFTC have been suggested as risk factors for aortic root dilation in the other studies too.[20],[25]
Our study was retrospective and we only could reassess the limited number of echocardiography images which had standard criteria based on ASE recommendations.[3] Although, at the beginning of the study, we had decided to measure the tubular portion of ascending aorta too, the number of eligible cases was not enough to address this goal, so our data confined to SOV diameter. A relatively small sample size was the other limit in our study. All patients with a history of TFTC surgery were not archived as TFTC or TOF patients in our center and due to limited time, we could not peruse all the available medical records. Therefore, measuring all levels of ascending aorta according to ASE criteria, and saving them in the PACS (picture archiving and communication system) and emphasizing on recording patients' weight, height, blood pressure and heart rhythm at each echocardiography report could be very helpful in future researches.
Although in our study, the frequency of aortic root dilation was about 68% in TFTC patients, SOV equal or more than 4.5 cm only found in <5%.
The only independent risk factors for dilated aortic root in this study include male sex, age at TFTC time and AR. We only found one case of aortic dissection among our patients. It seems despite the high prevalence of dilated aortic root in this population, but the adverse events are not so common, but it is still logical to evaluate all segments of ascending aorta on a yearly basis in TFTC patients with progressive aortic dilation.
Ethical clearance
The study was approved by the research and ethics committee of Rajaie Cardiovascular Medical and research Center with the ethical code of IR.RHC.REC.1400.012.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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