|Year : 2022 | Volume
| Issue : 3 | Page : 140-146
The angiographic study of right ventricular outflow tract and pulmonary artery anatomy in tetralogy of Fallot
Anusha Buchade, Usha M K Sastry, M Jayranganath, Bharath Adaligere Parshwanath
Department of Pediatric Cardiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India
|Date of Submission||16-Sep-2022|
|Date of Acceptance||31-Oct-2022|
|Date of Web Publication||14-Dec-2022|
Department of Pediatric Cardiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru - 560 069, Karnataka
Source of Support: None, Conflict of Interest: None
Objective: The objective of the study is to determine various anatomic variations in the pulmonary vasculature and associated cardiac defects in patients with tetralogy of Fallot (TOF).
Methods: This was a cross-sectional descriptive study conducted at Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bangalore from January 2009 to December 2017. A total of 100 patients irrespective of age and gender, who were subjected to cardiac catheterization were enrolled in the study which included all age groups. Measurement of pulmonary valve annulus, main pulmonary artery, right pulmonary artery (RPA), left pulmonary artery (LPA), and descending aorta was taken and corresponding z scores were calculated. McGoon ratio and Nakata index were also calculated.
Results: The age group in our study varied from 9 months to 49 years of age. Male-to-female gender ratio was 3:2. All patients had subvalvar (infundibular) stenosis and 82% of patients had stenosis at the valvar level. Seven patients had discrete stenosis, another seven patients had disconnection of RPA or LPA and six patients had supravalvar stenosis in the form of diffuse hypoplasia of one of the pulmonary arteries (PA). Significant communicating major aortopulmonary collaterals arteries (MAPCAs) were seen in 5% of patients and 16% of the patients had a persistent patent ductus arteriosus (PDA). Persistent left superior vena cava was present in 9 patients and 13% of the patients had coronary anomalies.
Conclusion: Subvalvular stenosis, confluence of PA, discrete, disconnected, and diffuse stenosis of LPA and RPA were the most common PA abnormalities found in patients with TOF. Significant-associated cardiac lesions including communicating MAPCA, PDA, and coronary anomaly were more commonly observed in these patients.
Keywords: Cardiac catheterization, pulmonary artery, tetralogy of Fallot
|How to cite this article:|
Buchade A, K Sastry UM, Jayranganath M, Parshwanath BA. The angiographic study of right ventricular outflow tract and pulmonary artery anatomy in tetralogy of Fallot. Heart India 2022;10:140-6
|How to cite this URL:|
Buchade A, K Sastry UM, Jayranganath M, Parshwanath BA. The angiographic study of right ventricular outflow tract and pulmonary artery anatomy in tetralogy of Fallot. Heart India [serial online] 2022 [cited 2023 Feb 2];10:140-6. Available from: https://www.heartindia.net/text.asp?2022/10/3/140/363544
| Introduction|| |
Tetralogy of Fallot (TOF) is a form of congenital anomaly characterized by pulmonary stenosis, an interventricular defect, biventricular aortal origin, and right ventricular (RV) hypertrophy. It is the most common cyanotic congenital heart disease; affecting 3–5 in 10,000 live births making 7%–10% of congenital defects.
About 50% of children with TOF died in the first few years of life due to a lack of surgical interventions, and few patients with TOF reach adulthood with an average life expectancy of 30 years. Nowadays, almost all the children born with this disease in all its variants can expect to live with the help of surgical repair and reach adult life. Intracardiac repair of tetralogy was first introduced by Lillehei et al. 1955. However, the age of receiving cardiac surgery to repair TOF has been slowly lessened with some units encouraging surgery at diagnosis, even within the early days of life.
Proper identification of pulmonary artery (PA) anatomy and associated variations is important for appropriate surgical planning. There have been many studies describing the variations in PA anatomy and associated anomalies across the world;,,, however, this was an attempt to look into the plethora of data available from our institution which operates TOF in big numbers. The objective of this study was to determine various anatomic variations in the pulmonary vasculature and associated cardiac defects in patients with TOF.
| Methods|| |
This cross-sectional descriptive study was conducted between January 2009 and December 2017 in the Department of Cardiology, at Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bangalore. After approval from the institutional ethics committee, written informed consent was obtained from all the patients before enrolment.
All patients irrespective of age and sex with a diagnosis of TOF subjected to cardiac catheterization were included in the study. Patients with post-BT shunt undergoing cardiac catheterization for further repair, TOF with pulmonary atresia, and TOF with absent pulmonary valve (PV) were excluded.
Patients were kept nil per oral with intravenous (IV) fluids for 6 h before the estimated time of procedure. Every patient was given an injection ceftriaxone 50 mg/kg 1 h before the procedure. Patients were subjected to cardiac catheterization under local anesthesia and sedation. Effective sedation and analgesia were maintained during the procedure, using midazolam and ketamine. Right femoral arterial and right femoral venous access were obtained using Selinger's technique. Anticoagulation was maintained during the procedure by administering IV heparin with a dose calculated at 100 IU/kg. Angiograms in standard views were taken. The right ventriculogram was done in anteroposterior (AP) view, with slight cranial angulation to define right PA (RPA) and left anterior oblique (LAO) cranial view to define left PA (LPA) if required. Left ventriculogram was done in LAO cranial view to look for additional ventricular septal defect (VSD). Aortic root angiogram was done in LAO view to delineate coronary artery. Selective cannulation of the coronary artery was done when root angiogram views were less clear. Aortic arch and descending aortogram were done in AP view to look for major aortopulmonary collaterals arteries (MAPCAs) and patent ductus arteriosus (PDA). Selective cannulation of each collateral was performed if significant. Selective angiograms of aortic branch vessels were taken to look for collaterals from branch vessels. The left innominate vein shoot in AP view taken to look for the persistence of left superior vena cava. Angiograms carefully viewed for the presence of doming of PV, on being present was considered stenotic PV. The arterial diameter was measured at the level of the pulmonary annulus, main PA (MPA), RPA, and LPA just before branching and descending aorta at the level of diaphragm.
“Z” scores of PV annulus diameter, main PA, right and left PA were noted. Any “z” score falling below 2 was considered hypoplastic.
McGoon's ratio was calculated by dividing the sum of the diameters of RPA (at the level of crossing the lateral margin of vertebral column on angiogram) and LPA (just proximal to its upper lobe branch), divided by the diameter of aorta at the level above the diaphragm ([DRPA/DDTAO]+[DLPA/DDTAO]). The normal value is 2.1. A ratio above 1.2 is associated with acceptable postoperative RV systolic pressure in TOF. VSD closure is deferred in patients with ratio below 0.8 at the time of repair or they underwent aortopulmonary shunt procedure as the first stage.
Nakata PA index is calculated from the diameter of PAs measured immediately proximal to the origin of upper lobe branches of the respective branch PAs. The sum of the cross-sectional area (CSA) of right and left PAs is divided by the body surface area (BSA) of the patient (Nakata index = CSA of RPA [mm2] + CSA of LPA [mm2]/BSA [m2]). A Nakata index of >150 mm2/m2 is acceptable for complete repair without a prior palliative shunt.
The outcome variables were angiographic findings (various associated lesions and anatomic variations) and their percentages were calculated. Since this was a descriptive diagnostic study, no test of significance was determined.
| Results|| |
A total of 100 patients with TOF were included in this study. There were 60 males and 40 females. The age of presentation was 9 months to 49 years and the mean age was 10 years. Three children underwent angiography at the age of 9 months. Majority of the patients had room air saturation in the range of 70%–90% and 63% of the patients has a BSA of <0.9 m2. Subvalvar obstruction in the form of infundibular stenosis [Figure 1]a and [Figure 1]b was present in all the cases. Valvar obstruction at the level of PV and supravalvar obstruction was seen in 83% and 17% of patients, respectively [Table 1].
|Figure 1: (a and b) RV angiogram of infundibular stenosis in AP. RV: Right ventricular, AP: Anteroposterior|
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|Table 1: Pulmonary artery abnormalities in patients with tetralogy of Fallot|
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Patients were evaluated for the presence of pulmonary valvular obstruction in the form of the presence of doming of valve leaflets [Figure 2]a and [Figure 2]b and pulmonary annular measurements. Annulus measurement was taken in every patient and the corresponding “z” score was < -2 in 14% of the patients. The diameter of the main PA was measured and corresponding “z” scores were < -2 in 26% of the patients. Similarly, the diameter of right and left PA was measured and corresponding “z” scores were < -2 in 2% and 3% of patients, respectively. In 4% of the patients, LPA was disconnected from MPA. Two patients had absent LPA.
|Figure 2: RVOT angiogram showing doming of PVs in (a) LAO cranial and (b) AP view. RVOT: Right ventricular outflow tract, PVs: Pulmonary valve, LAO: Left anterior oblique, AP: Anteroposterior|
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Confluent branch PA was found in 94% of the patients with TOF, however, six patients did not have confluence because of the absence of one of the branch pulmonary arteries [Figure 3]. Discreet stenoses at different levels were found in seven patients. Four patients had discrete stenosis of LPA, two at the level of insertion of ductus, one more distally, one at the origin of LPA with the absence of ductus. Three patients had discrete stenosis of RPA, at the origin, at the ostium, and at the level just before branching. Disconnection of one of the branch pulmonary arteries was found in seven patients. In four of the cases, the hilar LPA was present [Figure 4]a and [Figure 4]b, two patients had absent LPA with the left lung supplied by the collaterals from descending aorta. Another patient had absent RPA with a vertical duct continuing as RPA. Diffusely stenotic branch PA [Figure 5] was found in a total of six patients. Four of those patients had diffusely stenotic LPA, three of those patients had ductus, one joining MPA, and the other two inserting at the origin of LPA. One patient had abruptly cut off LPA distally. Two patients had diffuse stenosis of RPA.
|Figure 3: RV angiogram in LAO cranial view showing nonconfluent branch PAs with disconnected LPA. RV: Right ventricular, LAO: Left anterior oblique, PAs: Pulmonary artery|
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|Figure 4: (a and b) RV angiogram in LAO cranial view showing diffuse stenosis of RPA AP view showing pulmonary vein wedge injection unveiling the presence of hilar LPA. RV: Right ventricular, LAO: Left anterior oblique, RPA: Right pulmonary artery, AP: Anteroposterior, LPA: Left pulmonary artery|
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|Figure 5: RV angiogram in LAO cranial view showing diffuse stenosis of RPA. RV: Right ventricular, LAO: Left anterior oblique, RPA: Right pulmonary artery|
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Communicating and noncommunicating MAPCAs were present in 5% and 39% of cases respectively [Table 2]. MAPCAs from aortic arch branches were found in 12% of patients. PDA was present in 16% of cases. Additional VSD was present in only three patients which were mid-muscular in region. Right-sided aortic arch [Figure 6] was found in 20% of the patient.
|Table 2: Associated cardiac lesions found in patients with tetralogy of Fallot|
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A total of 13% of the patients had coronary anomalies [Figure 7] and [Figure 8] including a single coronary artery from the left sinus giving rise to left anterior descending (LAD), left circumflex artery (LCX), right coronary artery (RCA), RCA crossing right ventricular outflow tract (RVOT) (9%), LAD arising from right sinus and crossing RVOT (2%), and collaterals from LCX to the right lung and dilated and tortuous (1% each). Calculated McGoon's ratio showed that 46% of the patients had ratio >2.1 [Table 3]. Nakata's index represented that majority of patients (67%) had value more than 300 [Table 4]. Rare anomalies such as dextrocardia with situs inversus and right infundibular stenosis [Figure 9] and another patient with aortopulmonary window [Figure 10] were noted.
|Figure 6: Ascending aortogram in AP view showing right-sided aortic arch. AP: Anteroposterior|
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|Figure 7: Left coronary angiogram in LAO caudal view showing single coronary artery from left sinus giving rise to LAD, RCA, and LCX. LAO: Left anterior oblique, LAD: Left anterior descending artery, RCA: Right coronary artery|
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|Figure 8: Left coronary angiogram in RAO cranial view showing collateral from LCX supplying right hilum. RAO: Right anterior oblique|
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|Figure 9: RV angiogram in AP view showing dextrocardia with situs inversus with opacification of both aorta and PA with right infundibular stenosis. RV: Right ventricular, AP: Anteroposterior, PA: Pulmonary artery|
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|Table 4: Nakata's index distribution among patients with tetralogy of Fallot|
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|Figure 10: Ascending aortogram in AP view showing simultaneous opacification of PA suggestive of AP window later confirmed by CT. AP: Anteroposterior, PA: Pulmonary artery, CT: Computed tomography|
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| Discussion|| |
TOF is the commonest cyanotic congenital heart defect. Angiographic evaluation of the pulmonary arterial anatomy in TOF is essential first of all to identify the size of the pulmonary arteries. Thereafter, it is equally important to identify the severity of pulmonary arterial stenosis to assess their functional consequences following definitive repair.
In this study, the mean age of patients undergoing cardiac catheterization for evaluation of TOF was 10 years. A study was conducted on 1486 consecutive patients with TOF to determine coronary anomaly and the median age in their study was 3.5 years (range: 1 month to 51 years). Saeed et al. in their collection of 216 patients showed the mean age of presentation, relatively older with majority between 1 and 5 years of age. The mean age group is skewed toward higher age group which is atypical of presentation in TOF in our study because there was a significant contribution to our study population from the age group above 17 years.
Subvalvular stenosis in the form of infundibular stenosis was present in all the patients. A similar finding was observed in previous Indian stud. A study done by Sheikh et al., reported that isolated LPA stenosis (n = 60, 10.4%) and supravalvular stenosis as common abnormalities in patients with TOF.
In the present study, 82% of the cases had stenosis at the valvular level. All the PVs which showed evidence of doming on angiogram were grouped as stenotic irrespective of their annular measurement. In the current era, the valve-sparing surgery has been pushing its boundaries to include valves with “z” score of < “-4.” In this study, the lowest recorded PV “z” score was -3.59.
The third category was to define supravalvular stenosis either in the form of main PA stenosis or branch PA stenosis. In the current study, 17% had supravalvular stenosis. However, previous studies reported a comparatively higher prevalence of supravalvular stenosis in the range of 18%–38.9%.,,
The main PA “z” score revealed 26% of the values falling below 2. Discrete type of branch PA stenosis was found in 7% of the cases. Harikrishnan et al. noted that a prevalence of discrete pulmonary stenosis was as high as 29%. Further analysis showed that the presence of persistent PDA was found in 32/97 patients. Among the patients with PDA, the incidence of discrete stenosis was 25/32 (78%). Another study by Moon-Grady et al. who studied 700 infants with some form of RVOT obstruction out of which 373 patients had TOF, reported ductus-associated discrete PA stenosis of only 5% which is in contrast with the study mentioned above. Saeed et al. reported LPA stenosis in 32.14% of patients followed by MPA hypoplasia (21.43%).
PDA was present in 16% of patients in the present study. Saeed et al., reported 6% incidence of PDA. Sarawagi et al. reported 22.6% incidence of PDA. Harikrishnan et al. found a very high incidence of 32% of PDA whereas Sheikh et al. reported very low incidence of 5.4%.
Communicating MAPCAs were present in only 5% of our patients, and noncommunicating MAPCAs in 39% of patients. MAPCAs from arch vessels were seen in 16% of the patients. Saeed et al. had shown 1.8% of the incidence of MAPCAs. Similarly, Harikrishnan et al. recorded very low incidence of 1%.
Additional VSD was present in 3% of patients. Saeed et al. also recorded a low incidence of 5.5% of additional VSD. Sheikh et al. recorded 5.4% of additional VSD.
We recorded a 20% incidence of right-sided aortic arch in our patients. A similar prevalence of the right aortic arch was reported in previous studies (10%–23%).,,
In the present study, coronary anomalies were present in 13% of patients. Gupta et al. patients found a coronary abnormality in 104 patients (7%), Saeed et al. and Sheikh et al. reported a prevalence of 4.6% and 4.9%, respectively. However, in the present study, we found a different pattern compared to previous studies. In our study, a single coronary artery from left coronary sinus giving rise to LAD, LCX, and RCA, with RCA crossing RVOT was the most common anomaly.
An average value of McGoon ratio of 2.1 was noted in normal subjects. A ratio above 1.2 is associated with acceptable postoperative RV systolic pressure in TOF. Ratio below 0.8 is deemed inadequate for complete repair of PA-VSD. VSD closure is deferred in such patients at the time of repair or they underwent aortopulmonary shunt procedure as the first stage. In these patients, we found that 7% of the patients had a ratio of <0.8, and 46% of patients had a ratio of >1.2. However, this ratio tends to overestimate the adequacy of the size of PAs since this is derived using the diameter of descending thoracic aorta at the level of diaphragm which is frequently smaller in patients with PA-VSD.
In this study, more than 80% of patients had Nakata index of >150 mm2/m2. A Nakata index of >150 mm2/m2 is acceptable for complete repair without prior palliative shunt. While Nakata index is widely used in preoperative assessment of the adequacy of pulmonary vascular bed, it is not useful in patients with multifocal pulmonary blood supply, who are evaluated for single-stage repair of PA-VSD.
| Conclusions|| |
Subvalvular stenosis, confluence of PA, discrete, disconnected, and diffuse stenosis of LPA and RPA was the most common PA abnormalities found in patients with TOF. Significant associated cardiac lesions including noncommunicating MAPCA, PDA, and coronary anomaly were more commonly observed in these patients. Furthermore, detailed information on the anatomical variations are helpful for proper planning of surgery and also in risk stratification, prognostication, and outcome of surgery.
What is already known?
In the current era, every patient with TOF with access to cardiovascular surgery is amenable to repair. This, however, requires a proper identification of PA anatomy and associated variations for appropriate surgical planning.
What does this study add?
There have been many studies describing the variations in PA anatomy and associated anomalies across the world; however, this is an attempt to look into the plethora of data available from our institution which operates TOF in big numbers.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
The study was approved by the institutional ethics committee.
All authors contributed to design and conduct of the study, data collection, analysis and interpretation. AB wrote the manuscript. MKU, MJ and BAP critically reviewed and revised the manuscript. All authors provided the final approval for the manuscript to be published.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2], [Table 3], [Table 4]