Ophidian Cardiology—A Review

EFFECT OF BODY POSITION ON ECHOCARDIOGRAPHIC PARAMETERS IN PRAIRIE RATTLESNAKES (CROTALUS VIRIDIS)

Echocardiography is a noninvasive diagnostic tool that can provide instantaneous information about cardiac function, but it is uncommonly used by veterinarians to assess reptilian patients. Echocardiograms were performed on 14 clinically healthy, adult prairie rattlesnakes (Crotalus viridis), and cardiac measurements were taken in a horizontal and vertical position. Cardiac parameters including ventricular volume in systole and diastole, as well as the diameter of the left atrium, pulmonary artery, and paired left and right aortic arches were obtained. No evidence of cardiac disease was noted in any of the study animals. Males had a greater percentage of ventricular volume change (VVC) than females in the vertical position (P = 0.043). The percentage of ventricular volume change was significantly lower in the horizontal compared with the vertical position (P = 0.032) and was not different by sex. For the short-axis views, the right atrial diameter and short-axis ventricular area in diastole and systole were significantly smaller in snakes in the vertical compared with the horizontal position. This study is the first to obtain echocardiographic measurements in North American vipers and adds to the understanding of techniques used to evaluate the cardiac function of these species.

Two-dimensional and doppler echocardiographic evaluation in twenty-one healthy Python regius

Echocardiographic evaluation is a diagnostic tool for the in vivo diagnosis of heart diseases. Specific and unique anatomical characteristics of the ophidian heart such as the single ventricular cavity, a tubular sinus venosus opening into the right atrium, the presence of three arterial trunks and extreme mobility in the coelomic cavity during the cardiac cycle directly affect echocardiographic examination. Twenty‐one awake, healthy ball pythons (Python regius) were analysed based on guidelines for performing echocardiographic examinations. Imaging in the sagittal plane demonstrated the caudal vena cava, sinus venosus valve (SVV) and right atrium and the various portions of the ventricle, horizontal septum, left aortic arch and pulmonary artery. Transverse imaging depicted the spatial relationship of the left and right aortic arches, the pulmonary artery and the horizontal septum. Basic knowledge of cardiac blood flow in reptiles is necessary to understand the echocardiographic anatomy. The flow of the arterial trunks and SVV was analysed using pulsed‐wave Doppler based on the approach used for humans and companion mammals. The walls and diameters of the cavum arteriosum, cavum venosum and cavum pulmonale were also evaluated. This study should improve the veterinarian's knowledge of ophidian heart basal physiology and contribute to the development of cardiology in reptiles.

Comparison of three ECG machines for electrocardiography in green iguanas (Iguana iguana)

The aim of the study was to compare the heart rate, QRS interval, and R wave amplitude across three electrocardiogram models, and assess the ability of each of them to provide electrocardiograms (ECG) for clinical interpretation. The three electrocardiogram models included ECG Seiva Praktik Veterinary, CardioStore ECG and AliveCor Veterinary Heart Monitor. The data were collected from twelve healthy adult captive green iguanas (Iguana iguana) monitored under a manual restraint at a room temperature of 22.6-28.0 °C. The ECGs using the Seiva Praktik and CardioStore ECG veterinary electrocardiography were performed with standard 4 lead ECG recordings. The AliveCor Veterinary Heart Monitor was placed (with the use of gel) directly on the lateral body wall. The mean heart rate was 42 ± 8 beats/min (CardioStore), 50 ± 11 beats/min (Seiva Praktik Veterinary), and 51 ± 9 beats/min (AliveCor Veterinary Heart Monitor). No significant difference in the heart rate was observed. A significant difference (P < 0.05) in the QRS duration was observed between the CardioStore and AliveCor Veterinary Heart Monitor. Significant differences (P < 0.01) in the R wave amplitude were detected between the CardioStore and AliveCor Veterinary Heart Monitor and between the Seiva Praktik Veterinary and AliveCor Veterinary Heart Monitor. The ECGs produced by the Seiva Praktik VVeeterinary and CardioStore machines were interpretable at 100%, while those produced by the AliveCor Veterinary Heart Monitor were interpretable at 66%. Seiva Praktik Veterinary is most appropriately used as an anaesthesia monitoring tool. AliveCor Veterinary Heart Monitor could be used as an additional diagnostic tool, but the results should be ideally confirmed with a standard ECG machine. Seiva Praktik Veterinary is the most appropriate tool for monitoring the ECG within the anaesthesia, while CardioStore might be most appropriately used as an advanced diagnostic tool by virtue of its software assistance. The ECGs obtained with AliveCor Veterinary Heart Monitor should be confirmed using a standard ECG machine.

Standardisation of electrocardiographic examination in corn snakes (Pantherophis guttatus)

INTRODUCTION

Corn snakes are a very common pet reptile species, yet there is an absence of evidence-based literature standardising collection of ECG or detailing ECG deflection morphology in the normal animal. The authors describe a well-tolerated, reproducible technique and detail the cardiac cycle in terms of lead 2 equivalent waveforms and intervals.

ANIMALS

29 adult corn snakes.

MATERIALS AND METHODS

This prospective study evaluated, under species-appropriate, standardised conditions, a technique for producing standard six-lead ECG tracings. Lead 2 equivalent cardiac cycles were described in detail and statistically analysed for sex, weight, length, heart rate and mean electrical axis.

RESULTS

High-quality tracings demonstrated common ECG characteristics for this species, including no Q, S or SV waves, prolonged PR and RT intervals, rhythmic oscillation of the baseline, short TP segments, and a right displaced mean electrical axis. An influence of sex, weight or length on heart rate and mean electrical axis was not identified.

CONCLUSIONS

To the authors' knowledge, this is the first study to describe a standardised technique for recording ECG in significant numbers of normal corn snakes. Ranges have been provided that may be of diagnostic value or form the basis for future development of reference intervals for this species.

Technological Advances in Exotic Pet Anesthesia and Analgesia

Even when performed by skilled operators, locating the nerves can be challenging in small exotic pets; in such cases, the use of an electrical nerve stimulator may be useful to confirm the correct identification of the target nerve. Exotic animal anesthesia and analgesia have dramatically progressed over the past decade and continue to do so as more research and technologies develop. Technological advancements such as airway devices, endoscopic intubation techniques, positive intermittent pressure ventilators, and invasive and noninvasive blood pressure monitors have played a significant role in improving patient safety and the anesthetic outcomes of exotic animals.