Anatomical evaluation of a novel echocardiography based tricuspid valve classification in 60 hearts from body donors.

OBJECTIVES: This study aimed to provide comprehensive morphological descriptions of the morphology of the tricuspid valve and to evaluate if a novel echocardiography-based tricuspid valve nomenclature can also be understood anatomically. METHODS: Tricuspid valves of 60 non-embalmed human body donors without a medical history of pathologies or macroscopic malformations of the heart were included. Length, height and surface area of leaflets were measured. The valves were morphologically classified according to a novel echocardiography-based classification, in which 6 types are distinguished: classic 3-leaflet configuration, bicuspid valves, valves with 1 leaflet split into 2 scallops or leaflets and valves with 2 leaflets divided into 2 scallops or leaflets. RESULTS: We found a true 3-leaflet configuration in only 19 (31.7%) of valves. Five (8.3%) had a 2-leaflet configuration with a fused anterior and posterior leaflet. Of those, 3 had a divided septal leaflet. Four valves (6.7%) had a divided anterior leaflet, 17 (28.3%) had a divided posterior leaflet, 6 (10%) had a divided septal leaflet and 9 (15.0%) had 2 leaflets divided. Overall, 39 (65%) of valves have at least 1 leaflet that is divided. In 22 (36.7%) specimens, the leaflet was divided into true leaflets, and in 17 (28.3%) specimens, the leaflet was divided into scallops. In addition, we could identify 9 (15%) valves having 1 leaflet divided not only in 2 but 3 scallops or leaflets. CONCLUSIONS: This study provides further anatomical insight for the significant variability in the morphology of the tricuspid valve. By updating the understanding of its morphological characteristics, this study equips clinicians with valuable insights to effectively advance surgical and interventional treatment of tricuspid valves.

[Anatomical Identification and Possibilities of Transfer of the Masseteric Nerve for Facial Reanimation]. / Anatomische Auffindbarkeit und Möglichkeiten des Transfers des Nervus massetericus zur Gesichtsreanimation.

BACKGROUND: The masseteric nerve (MN) is often used as a donor nerve for facial reanimation. In addition to already established techniques, MN transfer is rapidly gaining importance, mainly due to the single-stage approach of the procedure and its reconstructive potential. This anatomical study and the associated questionnaire study aimed to evaluate the established methods for identification of the MN and its suitability for direct nerve transfer as well as to assess the importance of MN transfer in the daily clinical routine. MATERIAL AND METHODOLOGY: Bilateral dissection of 25 fresh-frozen head specimens (n=50; 13 female, 12 male) was performed with accompanying measurement of the MN. In a questionnaire study conducted at established centres for facial surgery in German-speaking countries, clinical experience data of MN transfer was collected using the SurveyMonkey software. The data obtained was statistically analysed using Microsoft Excel and presented in numerical tables and boxplots. RESULTS: Using anatomical landmarks such as the zygomatic arch and the mandibular notch for orientation, the MN was found in 100% of cases. Its average length from the emerging point below the zygomatic arch towards its entry into the masseter muscle was measured to be 22 mm and was the length available for nerve transposition. Tension-free coaptation of the MN with the zygomatic branch was possible in 94% of cases. The questionnaire showed that the MN is considered an important donor nerve for motor nerve transfers and that MN transfer is now largely established as a standard procedure. DISCUSSION: In accordance with previously published studies, the MN was reliably found at the height of the mandibular notch and, in the vast majority of cases, was suitable for tension-free coaptation with the zygomatic branch. Differences to the existing literature, however, can be seen in the length of the nerve available for nerve transposition and the frequency of its division into several branches before entering the masseter muscle. In German-speaking countries, Cross-Face Nerve Grafting (CFNG) is still the preferred method for facial reanimation surgery. However, MN transfer is also well established by now, both as an alternative and a supplement to other techniques, possibly due to its low donor site morbidity and short time to regeneration.

Characterization, number, and spatial organization of nerve fibers in the human cervical vagus nerve and its superior cardiac branch.

BACKGROUND: Electrical stimulation of the vagus nerve (VN) is a therapy for epilepsy, obesity, depression, and heart diseases. However, whole nerve stimulation leads to side effects. We examined the neuroanatomy of the mid-cervical segment of the human VN and its superior cardiac branch to gain insight into the side effects of VN stimulation and aid in developing targeted stimulation strategies. METHODS: Nerve specimens were harvested from eight human body donors, then subjected to immunofluorescence and semiautomated quantification to determine the signature, quantity, and spatial distribution of different axonal categories. RESULTS: The right and left cervical VN (cVN) contained a total of 25,489 ± 2781 and 23,286 ± 3164 fibers, respectively. Two-thirds of the fibers were unmyelinated and one-third were myelinated. About three-quarters of the fibers in the right and left cVN were sensory (73.9 ± 7.5 % versus 72.4 ± 5.6 %), while 13.2 ± 1.8 % versus 13.3 ± 3.0 % were special visceromotor and parasympathetic, and 13 ± 5.9 % versus 14.3 ± 4.0 % were sympathetic. Special visceromotor and parasympathetic fibers formed clusters. The superior cardiac branches comprised parasympathetic, vagal sensory, and sympathetic fibers with the left cardiac branch containing more sympathetic fibers than the right (62.7 ± 5.4 % versus 19.8 ± 13.3 %), and 50 % of the left branch contained sensory and sympathetic fibers only. CONCLUSION: The study indicates that selective stimulation of vagal sensory and motor fibers is possible. However, it also highlights the potential risk of activating sympathetic fibers in the superior cardiac branch, especially on the left side.