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Hypothesis and Background: A high prevalence of downwardly sloping type 3 Aortic Arch (AA) in elderly humans with Left Ventricular Hypertrophy (LVH) led us to hypothesize that Major Aortic Arch Branches (MAAB) acting through the AA and ascending Aorta are pivotal in subtending the heart in its anatomic position. Based on established commonality in comparative anatomy of terrestrial mammals we tested our hypothesis in the even-toed ungulate model. Methods and Results: We observed 5 animals (2 sheep and 3 goats) at a licensed abattoir as they were being dressed, in a requested order. In vertical orientation, midline incision bisecting the entire chest and anterior abdominal wall was made and after retracting the ribs the heart was visualized. In stepwise fashion: abdominal organs, diaphragm, lungs and Vertebropericardial Ligaments (VPL) were removed; in all animals, the heart maintained its position in the thorax after the above steps. Subsequently, Sternopericardial Ligaments (SPL) were transected and the heart still maintained its position. Only after ascending aorta was severed just above the Aortic valve, did the heart lose its position and drop down to the pelvis. Conclusion: In even-toed ungulate animal model, MAAB acting through AA and ascending aorta are pivotal in subtending the heart in its usual anatomic position. Invoking basic principles of comparative anatomy it would be safe to extrapolate that same may run true in humans. Indirect evidence of above in humans may reside in a high prevalence of downwardly sloping type 3 AA in elderly with LVH.

The study was conducted in 12 adult female buffaloes suffering from diaphragmatic hernia (DH). The animals were randomly divided in 2 groups of 6 each. DH was repaired under general anaesthesia using glycopyrrholatexylazine-butorphanol-thiopentone maintained with isoflurane and sevoflurane in group TI and TS, respectively. Clinical and behavioural parameters were observed during herniorrhaphy while physiological, haematological and biochemical parameters were recorded at different intervals (before rumenotomy, before premedication, 5 min after thiopentone injection, at 15 min and 30 min of inhalant anaesthesia, at recovery and at 24 h of recovery). No significant difference was seen in sedation, muscle relaxation and analgesia scores between the groups. The respiratory rate was less depressed and corneal reflex was mostly intact during maintenance in TS group. Recovery and standing with ataxia in TS group was significantly earlier than TI group. There was no significant difference in haematological and blood biochemical parameters between the groups. The results indicated that sevoflurane is a better maintenance agent than isoflurane for maintenance of general anaesthesia in buffaloes undergoing DH.