The 100 most cited papers on total anomalous pulmonary venous connection: a bibliometric analysis

In this study, we identified the most cited papers on TAPVC and also summarized the characteristics of highly cited articles. The lists of the most cited papers demonstrated the history and development on TAPVC. To our knowledge, this is the first study on the most cited articles in the field of TAPVC. This list of 100 most cited papers is of substantial importance for several reasons. Authors can learn about the research hotspots and shape their research interests. This list can serve as an education tool for residents and directors so that they can be familiar with the classic papers on TAPVC [4]. Journal editors and reviewers can identify potential highly cited papers with a prior knowledge of typical characteristics of such papers when they evaluate submitted manuscripts. Clinicians can apply important findings to the clinical practice, therefore patients may obtain better outcomes.

The most cited paper on the list, which described 93 autopsied cases with TAPVC, was written by Delisle et al. in 1976 [5].This manuscript found that TAPVC was failure of development of the common pulmonary vein with collaterals between the lungs and the systemic veins. TAPVC was a rapidly fatal disease and the age at death was influenced by obstruction of the anomalous venous pathway. TAPVC could almost always be corrected by surgery according to the anatomy. This paper emphasized diagnostic and surgical considerations in TAPVC. The second most cited article, which presented the clinical and physiologic observations of 75 pediatric patients with TAPVC, was written by Gathman et al. in 1970 [6].The authors proposed an approach to managing TAPVC. Patients with pulmonary venous obstruction should undergo early surgery. Patients with pulmonary hypertension without pulmonary venous obstruction should receive medical intervention. If pulmonary hypertension was not present and particularly if there was a significant gradient across the right ventricular out flow tract, medical treatment might to be recommended until operation could be performed.

The oldest paper on the list, which described three patients with TAPVC, was written by Parsons et al. in 1952 [7].At that time, the anastomosis of pulmonary veins to the appendage was feasible only in the experimental animal. The authors proposed that it should be possible to correct anomalous pulmonary veins by transplantation of pulmonary veins in man. This paper laid the foundation for the surgical repair of TAPVC. The latest paper on the list, which explored the potential genetic abnormalities in patients with TAPVC through next-generation sequencing, was written by Shi et al. in 2018 [8]. This study identified SNAI1, HMGA2 and VAV2 as novel candidate genes associated with TAPVC and provided novel insights into pulmonary vein development. This paper is helpful to understand the pathogenesis of TAPVC.

Interestingly, one of the 100 most cited papers which ranked 21 was published by our team in Circulation. [9] This multi-institutional study used a large cohort of patients (768 patients) to assess the impact of current management strategies on the outcomes of TAPVC. This study found that contemporary outcomes after surgical repair for TAPVC were acceptable. This study examined risk factors associated with outcomes and suggested that computed tomography angiography plays an important role in the preoperative morphological evaluation of TAPVC and is useful in preoperative surgical planning. This study also found that compared with the conventional repair, the sutureless technique could reduce the restenosis rate in patients with preoperative pulmonary venous obstruction (PVO) and that no statistical difference was found in patients without preoperative PVO. Our team is dedicated to the study of TAPVC and has published some related articles recently.

Compared with bibliometric analyses in other specialties, the number of citations of the 100 most cited papers on TAPVC is much lower. The highest cited paper in a bibliometric analysis on mitral valve surgery received 1348 citations with a mean (range) citation of 248 (148–1348). [10] The highest cited paper in a bibliometric analysis on minimally-invasive cardiac surgery received 414 citations with a median (range) citation of 101 (51–414). [11] It might indicate that a lower degree of research activity within TAPVC in comparison to more established fields.

Our analysis found that the 100 most cited articles were published in 24 journals. A total of 79 articles were published in only 10 cardiovascular specialty journals. This shows a trend of publishing influential papers in specialty journals compared with non-specialty journals. Our findings supported the application of Bradford’s law, a bibliometric concept put forward by Brookes and Siegelman [12, 13]. The main idea behind Bradford’s law is that researchers obtain citations from a few core journals in their specialized field. When researchers deviate from core journals, the citations and impact fall. This trend makes most highly cited papers come from a few professional journals.

Considering the fact that the journal impact factor is calculated based on the number of citations, the journal impact factor should be positively correlated with the status of citations. But the results of previous bibliometric papers on different specialties have not been consistent in this relationship. Some studies demonstrated that the journal impact factor was positively correlated with the number of the most cited papers and citations [14], while some others did not [11]. The correlation between journal impact factor and the status of citations on TAPVC was weak in our study. Our study did not support the well-known law that the most cited articles are often published in journals with high impact factor, which in turn contribute to the high impact factor of these journals. The possible reason is that compared with other specialities, TAPVC is still a very new field of interest and currently in its infancy. The weak relationship may be due to a lack of time, and will strengthen as the field develops and time passes.

All the 100 articles except one were published in English and only 18 papers originated from non-English speaking countries. It demonstrated the dominance of English in the scientific community. The majority of highly cited papers were from the USA. This phenomenon also exists in other disciplines which indicates the leadership of the USA in the scientific community. It may be due to the large population of researchers and sufficient financial support for scientific research in USA. However, there could be many other potential factors that lead to the dominance of USA. There is a tendency that American authors cite native papers and American journals accept papers from native authors [15, 16]. It is generally accepted that scientific research output depends on the national economy [17]. But the results of previous bibliometric papers on different specialties have not been consistent in this relationship. Some bibliometric papers found a significantly positive correlation between GDP per capita and the status of citations [18], while some other bibliometric papers could not [19]. The correlation between the GDP per capita and the number of the 100 most cited papers on TAPVC was weak in our study. This may be explained by the limited number of papers and countries, government policy, the level of research and medical infrastructure, research funding, the culture around research, research and development, the number of universities and research institutions [20].

Clinical research bridges the gap between basic science and clinical practice. Our analysis demonstrated that the vast majority of papers on TAPVC were clinical studies. Similar with previous studies, there is lack of papers with high level of evidence. Randomized controlled trial (RCT) tops the evidence pyramid and facilitates the application of research findings to clinical practice decisions [21]. However, RCT-based study does not exist on TAPVC. The likely reason is that TAPVC can only be treated with surgical repair and RCT in surgery may be difficult to achieve. Another reason may be that new findings are usually initially published as observational studies, and still receive the attention of the researchers. The list of the most cited papers shows some hot topics in TAPVC research. Surgery is the most popular topic in the list as surgical repair is the only effective treatment. Diagnosis of TAPVC remains controversial. Therefore, radiology is another hot topic in the field of TAPVC.

Fund support is a great boost to medical research. In our study, 31 papers reported funding support from public foundations. However, our review showed that no research projects received grants from commercial resource. Although commercial support is debated because of the susceptibility to various kinds of biases, it has played a critical role in the research process. A remarkable thing should be considered that some old papers might not have fully reported their financial conflicts.

We also demonstrated that the majority (84 papers) of the most cited articles were published after 1970. Our finding is also verified in other bibliometric analyses [4, 14]. The body of literature has flourished tremendously and great progress has been made in recent years in the field of TAPVC, and clinicians tend to rely on the latest literatures, which may explain this phenomenon. There were no papers published before 1950 in the list which indicates that old papers have limited value in modern times. However, it is important to realize that this trend could be influenced by multiple issues. Limitations in the database for indexing older literatures, lack of online resources, and the tendency to publish papers in the form of textbooks in the early times may contribute to this trend.

Although we have tried to reduce potential biases, some limitations were inevitable and inherent to citation analysis. First, citation analysis is not a perfect method to measure the impact of an article on the scientific community. Citation analysis is not a measure of the quality of an article, but rather the recognition. In other words, the number of citations an article receives does not accurately reflect its importance. Second, The overall number of citations an article is cited used as a measure of impact will favor older articles and omit important articles from the past 10 years [22]. The number of citations an article receives depends on its publication year, since citations accrue over time. Third, there is a snowball effect in citations due to adherence to scientific paradigms [23]. Some authors tend to cite certain articles, simply because they have been cited for many times rather than for their importance. Fourth, the bibliometric phenomenon, termed “obliteration by incorporation” is also a confounder. Some pioneering studies are assimilated into current knowledge and no longer cited. These important works may be underestimated with respect to the impact on the scientific community. Fifth, authors do not necessarily cite the articles that have influenced them most. Citing is a complex process with many motives and are strongly affected by self-citation, in-house citation, citing high-impact journals and review articles, and national or language preferences [24, 25]. Last, we performed the citation analysis with only one of the many available databases. No database is considered superior, and the number of citations an article receives varies greatly across different databases [26‐28]. It is possible that many articles that were not included on our list may be included if we use other databases for citation analysis.