A case report: An aortobifemoral bypass implant found during cadaver dissection promotes inquiry-based learning.

INTRODUCTION: An unusual vascular implant found during routine cadaver dissection influenced instructors and students to learn more about the underlying disease and the surgical technique used to treat this disorder triggering an inquiry-based learning. PRESENTATION OF CASE: This report describes a case of peripheral arterial disease (PAD) with an aortobifemoral arterial bypass implant that was never found before in any of the previously dissected cadavers at Gannon University. DISCUSSION: PAD develops due to impaired blood flow to the lower extremities that causes numbness, weakness, and lower leg pain. The treatments can aim to improve the long-term cardiovascular outcomes. If therapeutic medications do not improve outcomes of PAD, revascularization by endovascular repair or aortofemoral bypass grafting is considered.
CONCLUSION: We would like to note that accidental discoveries of pathologies or surgical procedures during routine cadaveric dissections present a unique possibility for inquiry-based learning among future healthcare providers.

Introduction

Gannon University has the luxury of teaching the future health care professionals about the human body through rigorous lecture and laboratory courses [1]. Cadaver-based human gross anatomy (HGA) is taught to undergraduate college students in pre-med, physical therapy, and physician assistant majors. Here students will be involved in dissecting their own cadavers as well as observing and learning structures within the prosected cadavers. The most difficult challenges about partaking in this course is memorizing the magnitude of information that is presented within lecture as well as structures within laboratory. Often times, in order to obtain a firm understanding of the material, pathologies discovered within the laboratory help solidify the material presented within lecture [2]. Here, we present a case of peripheral arterial disease, also commonly expressed as PAD, with an aortobifemoral arterial bypass implant that was never found before in any of the previously dissected cadavers at Gannon University HGA laboratory over the past 22 years. The work reported within this manuscript is in line with the SCARE criteria [3].

Peripheral arterial disease is a circulatory disorder which develops due to impaired blood flow most commonly to the lower extremities [4]. The symptoms of PAD include numbness, weakness, paleness, changes in skin (temperature, color) and lower leg pain. Although PAD is a slow occurring disease, the treatments via specialized physicians can aim to help improve the peripheral vasculature and circulation, and to improve the long-term cardiovascular outcomes. If medications do not improve outcomes of PAD, surgical revascularization by endovascular or aortofemoral bypass grafting is considered for those with critical limb ischemia or claudication symptoms.

Here, we present a case of PAD with aortobifemoral bypass implant that was unexpectedly found in a female cadaver during regular dissection which triggered curiosity and excitement among undergraduate students at our university. We previously never had come across similar vascular implants in dissected cadavers, nor did we know much about PAD; therefore, we used this case to promote inquiry-based learning among health professions students. The inquiry-based learning offers promise in supporting students to become thoughtful, motivated, collaborative and innovative learners capable of engaging in their own inquiries and prepare themselves for thriving in a professional world of constant change and competition [5].

We found that human gross anatomy teaching can become engaging if inquiry-based learning using clinical cases is incorporated in the curriculum to promote active-learning among undergraduate students [5]. It was our experience that finding pathologies or post-surgical implants in cadavers creates excitement and a unique inquiry-based learning experience in human gross anatomy courses which may not necessarily be possible in teaching human gross anatomy using digital cadavers.

Case presentation

An 80 year-old Caucasian female formalin-embalmed cadaver was used for educational purposes in Gannon University human gross anatomy laboratory. She was diagnosed with cardiovascular disease at the time of death. Following dissection of the retro-peritoneum and preparation of the abdominal aorta and its branches, an aortobifemoral arterial bypass implant was found (Fig. 1, Fig. 2). In an individual without any morphological variation, the abdominal aorta is a continuation of the thoracic aorta beginning at the level of the twelfth thoracic vertebra. The abdominal aorta runs along the left anterolateral aspect of the lumbar spine, and at approximately the fourth to fifth lumbar vertebrae level the common iliac arteries branch from the aortic bifurcation and extend downward and outward to the groin (Fig. 3). The inferior vena cava runs parallel to the right side of the abdominal aorta.

Fig. 1

Photographic pictures of the abdominopelvic cavity and thigh showing aortic tree together with the aortobifemoral grafting: (A) Dissection illustrating the abdominal aorta and aortobifemoral implant within the area selected by the yellow box; (B) Higher magnification of the selected area in Fig. 1A. The entire length of the inverted Y-shaped aortobifemoral implant is marked with red asterisks, the blue arrow indicates the single end of the Y sewn on the aorta just below the branching of renal arteries, and the yellow arrows indicate the two split ends of the Y sewn below the blocked areas of the femoral arteries.

Fig. 2

Photographs of both ends of the Y-shaped aortobifemoral implant: (A) Higher magnification of the single end of the Y-shaped implant (Y) sewn on the aorta (asterisk) just below the branching of renal arteries; (B) Higher magnification of the split end of the Y-shaped aortobifemoral implant (Y) sewn below the blocked area of the left femoral artery (asterisk). Abbreviations: TA, thoracic aorta; AA, abdominal aorta; DIAPH, diaphragm; CT, coeliac trunk/artery; SMA, superior mesenteric artery; RA, renal artery; LK, left kidney; IL, site of the inguinal ligament; LEIA, left external iliac artery; LFA, left femoral artery; LFV, left femoral vein; LGSV, left great saphenous vein.

Fig. 3

Schematic drawings of aortobifemoral bypass grafting: (A) Normal aortic tree; (B) Schematic representation of Fig. 1A. End-to-side anastomosis for direct revascularization of the aortoiliac segment creates a bypass for blood to travel around the blocked sections of the diseased areas in the arteries.

The aortobifemoral arterial bypass implant found in the cadaver was made of synthetic material (most likely polytetrafluoroethyline or Dacron), and it extended between abdominal aorta and femoral arteries (Fig. 1, Fig. 3B). The part of abdominal aortic wall immediately distal to the renal arteries was found to be calcified. Similar to the aorta, the common iliac arteries also showed calcification (Fig. 3B), whereas, calcification in the walls of abdominal vena cava was not observed. Aortobifemoral bypass graft was constructed to provide straight-line flow to the femoral arteries and to preserve flow to the internal iliac, inferior mesenteric, and lumbar arteries. The synthetic implant was formed into a Y shape with the single end of the Y was sewn on the aorta just below the branching of renal arteries to create the proximal aortic anastomosis in end-to-side fashion (Figs. 2A and 3 B). The two split ends of the Y were sewn below the blocked areas of the femoral arteries (Figs. 2B ad 3 B). This created a bypass for blood to travel around the blocked section of the diseased areas in the arteries.

Discussion

Henri Marie Bouley, a pioneering French veterinarian and pathologist, first came across the condition of PAD as he was examining a horse [6]. Later, in 1846, Brodie discovered the first noted condition within humans [7]. The pathophysiology of PAD is developed via the atherosclerotic plaque development within the peripheral arteries. Location of plaques within the abdominal aorta is most prevalent at the bifurcation into the iliac vessels where the separation of vessels can lead to the increase in platelet aggregation resulting in subsequent atherogenesis and vascular stenosis [8].

According to epidemiology, it is estimated that greater than 200 million people are diagnosed with PAD worldwide, with symptoms ranging from asymptomatic to severe [9]. The risk of PAD greatly increases because of global trends in population ageing, the diabetes mellitus pandemic, and the spread of chronic kidney disease. Importantly, these risk factors often predispose a patient to more distal vessel involvement [10]. The clinical presentation of PAD can be classified into asymptomatic disease, intermittent claudication and limb-threatening ischemia, and the last two conditions are considered for revascularization [11]. The direct aortoiliac endovascular repair is performed in patients with claudication, whereas surgical vascular reconstruction using aortofemoral bypass grafts is performed more commonly on patients with limb-threatening ischemia [12]. Aortobifemoral bypass grafts are constructed between abdominal aorta and the femoral arteries to preserve flow to the lower extremities. As major vascular surgery, several complications can occur postoperatively [11]. In particular, if careful postoperative management including regular graft surveillance programs is not performed, it would lead to poor outcomes after surgery [13].

The present case of PAD with aortobifemoral bypass implant was the first case found at the human gross anatomy laboratory at Gannon University within past 22 years, and this finding triggered curiosity within the classroom. Clinicians have been suggesting that anatomy teaching should be more closely integrated with clinical teaching and that anatomy education must contribute to the development of professionalism-related competencies [14]. Here, we attempted to inculcate inquiry-based learning that promotes clinical reasoning skills among students [5]. We used this unexpected finding during dissection as a stepping stone for generating group processes. Inquiry-based learning is one such strategy that promotes students to actively and increasingly independently investigate questions and problems that are related to their interests or future professions [5]. This learning strategy emphasizes the development of skills that extend beyond the confines of the classroom. Medical professionals of all expertise believe that cadaveric dissections complemented with other innovative learning methods lay strong foundation critical to development of clinical skills [15].

The use of human cadavers as an educational tool started in the 16th or 17th century; however, once considered a cornerstone of medical education, the practicality and usefulness of cadavers as an educational tool is under large scrutiny and heavy debate at present [16]. With the advancement in digital technology, the use of cadavers is largely believed to become obsolete [17]. Digital technology is becoming a popular and budget-friendly alternative to cadaver dissections [17]. This development ultimately raises the question as to whether we should continue teaching anatomy by dissection. Indeed, during the last two decades, several universities in the US and the UK have moved from a cadaver-oriented to a cadaver-less anatomy [18]. Despite this, many academic institutions still continue to use the human cadavers in the classroom [19]. Supporters for the use of cadavers argue that students will miss out on seeing natural anatomical variations that exist in human bodies, and students may also lose the emotional impact of working with a cadaver, commonly seen as a clinician's first patient, that provides great details about the complex human body structures with or without any existing pathology [15,20]. At our university, quite often, the undergraduate students have an intrinsic fear of studying human gross anatomy due to the vast material that needs to be memorized passively; however, any finding of an anomaly among cadavers clearly ignites curiosity and engagement among students and promotes inquiry-based active learning. It allows the instructors and teaching assistants to provide additional information about the anomalies and pathologies seen, and we incorporate this material in course assessments.

Conclusion

The main aim of the present study was to demonstrate how to inculcate inquiry-based learning among students learning human gross anatomy. During the dissections, the first-hand experience in finding pathologies or post-surgical implants in cadavers creates a unique learning experience and excitement in human gross anatomy courses which may not necessarily be available in digital cadavers. The case of PAD with aortobifemoral bypass implant presented here was the first case found in the human gross anatomy laboratory at Gannon University. We used this case to promote inquiry-based learning among students.

Smoking, hypertension, hypercholesterolemia and/or other abnormalities are responsible for the development of PAD in most cases. The general prognosis of PAD is positive as long as the individual actively pursues lifestyle modifications to reduce risk factors. The treatment for PAD often times can be noninvasive depending on the severity and progression of the disease; however, as the symptoms progress to more severe complications, revascularization surgery is implemented to reduce the complications of PAD.

Funding

.

Ethical approval

This study is exempt from ethnical approval in Gannon University

Consent

Written, informed consent was taken from the cadaver-donating institution, the Wright State Anatomical Gift program and the Booneshaft School of Medicine for the permission to report this case study. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Author contribution

Zachary P. Gotham: Investigation, Writing - original draft preparation, Reviewing and Editing

Rachel S. Tanilli: Investigation, Writing – Reviewing and Editing

Olivia M. Wirfel: Methodology, Writing – Reviewing and Editing

Prasad S. Dalvi: Investigation, Conceptualization, Methodology, Supervision and Project Administration, Writing, Reviewing, Editing, Validation

Registration of research studies

1. Name of the registry: Not applicable

2. Unique identifying number or registration ID: Not applicable

3. Hyperlink to your specific registration (must be publicly accessible and will be checked): Not applicable

Guarantor

Prasad S. Dalvi, MD, PhD,

Zurn Science Center, Room 250

109 University Square

Erie, PA 16541, USA

Phone: +1-814-871-5963

Email: dalvi001@gannon.edu

Fax: +1-814-871-5319

Provenance and peer review

Not commissioned, externally peer-reviewed

Declaration of Competing Interest

No conflict of interest to disclose.