in Ruminants

div epub:type=”chapter” role=”doc-chapter”>



© Springer Nature Singapore Pte Ltd. 2020
J. VarshneyElectrocardiography in Veterinary Medicinehttps://doi.org/10.1007/978-981-15-3699-1_18


18. Electrocardiography in Ruminants



J. P. Varshney1 


(1)
Veterinary Medicine, Shri Surat Panjarapole Prerit Nandini Veterinary Hospital, Surat, Gujarat, India

 



18.1 Electrocardiography


Though electrocardiography is routinely employed for monitoring cardiac rhythm, rate, conduction disturbances, and size of the chambers of the heart in man, dogs, and cats, its use in ruminants is restricted to monitoring of heart rate and rhythm only. Detection of cardiomyopathy from electrocardiogram is not feasible in ruminants (cows, buffaloes, sheep, goat) and other hoofed mammals (pigs and horses) due to deep penetration of Purkinje fibers from endocardium to epicardium and cross-fiber bridges and depolarization and repolarization occurring over multiple minor fronts at a time. Nevertheless, identification of arrhythmias and conduction disturbances is of immense clinical value in ruminants also. Early detection of arrhythmias of severe nature and electrolyte imbalance might enable large animal practitioners to take appropriate remedial measures and to assess an accurate prognosis of ailing animals.


The generation of electrocardiogram in ruminants is due to depolarization and repolarization of cardiac muscle fibers similar to canines and felines. The wave of depolarization begins in sinoatrial node (SA node) and passes through atrium producing “P” wave and reaches to AV node. The delay in conduction at AV node results into P-R segment. Then depolarization of ventricles occurs producing “QRS” complex followed by isoelectric period, i.e., S-T segment. This is followed by repolarization of the heart represented by “T” wave. The values of amplitude and duration of complexes and intervals in ruminants vary from that of dogs and cats.


Positioning of animals: The animals (cow, buffalo, goat, sheep, mithun) are kept standing on a rubber mat, and the sites for applying alligator clips are prepared by shaving and cleaning with alcohol. Gel is applied liberally on the areas of attachment of electrodes.


Placement of electrodes and recording of ECG: Traditional lead system in large animals was based on Einthoven’s triangle using standard bipolar limb leads and augmented unipolar limb leads as in case of humans, dogs, and cats. In this lead system, ECG wave forms are affected by the variations in limb position, and complexes are small. Other lead system, i.e., base-apex lead system, where such variations of limb positioning have less impact, is more appropriate in large animals. In base-apex lead system, the right arm electrode is attached to the neck in the left jugular furrow two third down in the neck, left arm electrode is placed over the apex of the heart just behind the left elbow, and earth electrode (right hind leg electrode) is attached at wither (Figs. 18.1, 18.2, 18.3, 18.4, and 18.5). Electrocardiogram is recorded in a calm and quite surroundings using electrocardiographic machine at a paper speed of 25 mm per second and amplitude of 1 mV per 10 mm. The recording is done in lead I. In hexaxial lead system, forearm electrodes are attached at anterior aspect of respective olecranon on medial side of the elbow joint, and hind limb electrodes are placed on medial aspect of respective stifle joint (Fig. 18.6) similar to canines.



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig1_HTML.jpg

Fig. 18.1

Placement of electrodes in buffalo calf (base-apex system)



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig2_HTML.jpg

Fig. 18.2

Placement of electrodes in cow calf (base-apex system)



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig3_HTML.png

Fig. 18.3

Placement of electrodes in sheep (base-apex system)



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig4_HTML.png

Fig. 18.4

Placement of electrodes in goat (base-apex system)



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig5_HTML.jpg

Fig. 18.5

Placement of electrodes in mithun (base-apex system) (Courtesy Dr. Akhalesh Kumar)



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig6_HTML.jpg

Fig. 18.6

Placement of electrodes in buffalo calf (hexaxial system)


18.1.1 Electrocardiogram in Buffalo and Cow Calves


Electrocardiogram of ruminants is having “P,” “QRS,” and “T” complexes, P-R interval, S-T interval, Q-T interval, and R-R intervals (Fig. 18.7) as also seen in other animals. But “QRS” complex in ruminants is predominantly negative in the form of “rS” (Figs. 18.8 and 18.13) or “QS” (Figs. 18.9 and 18.14), and the “T” wave is either positive (Fig. 18.9), negative (Fig. 18.10), or biphasic. “P” waves may be either round, peaked, or slightly isoelectric in configuration.


Complexes are significantly (P < 0.05) large in lead I of base-apex (Fig. 18.11) than those of lead II of hexaxial lead (Fig. 18.12) system.



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig7_HTML.jpg

Fig. 18.7

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of a 1-year-old calf showing complexes, duration, and intervals. QRS complex is QS type and predominantly negative



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig8_HTML.png

Fig. 18.8

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of Surti buffalo calf showing “rS”-type QRS pattern



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig9_HTML.png

Fig. 18.9

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of Surti buffalo calf showing “QS”-type QRS pattern and positive T wave



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig10_HTML.png

Fig. 18.10

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of a Holstein crossbred calf showing negative “T” wave



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig11_HTML.png

Fig. 18.11

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of Surti buffalo calf. Note the size of “P,” “QRS,” and “T” waves



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig12_HTML.png

Fig. 18.12

Electrocardiogram (hex axial lead system, lead II, speed 25 mm/s, and sensitivity of 1.0) of the same Surti buffalo calf (Fig. 252) employing hexaxial lead system (lead II). Note the size of the complexes. The size of “P,” “QRS,” and “T” is smaller as compared to that of base-apex lead system (Fig. 18.11)



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig13_HTML.png

Fig. 18.13

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of Holstein crossbred calf showing “rS”-type QRS pattern and + ve “T” wave



../images/489736_1_En_18_Chapter/489736_1_En_18_Fig14_HTML.png

Fig. 18.14

Electrocardiogram (base-apex lead I, speed 25 mm/s, and sensitivity of 1.0) of Holstein crossbred calf showing “QS” type QRS pattern


18.2 Electrocardiographic Indices in Buffaloes


Values of electrocardiographic indices in healthy Surti buffalo calves are given in Table 18.1. Mean values of heart rate, “P” amplitude, “P” durations, “R” segment, “P-R” interval, “QRS” amplitude, “QRS” duration, “S-T segments” amplitude, “T” duration, “Q-T” interval, and “R-R” interval in buffaloes have been reported as 90.39 ± 3.44 bpm, 0.195 ± 0.010 mV, 0.0513 ± 0.0014 s, 0.11 ± 0.0558 s, 0.166 ± 0.056 s, 0.877 ± 0.062 mV, 0.051 ± 0.0017 s, 0.167 ± 0.034 s, 0.278 ± 0.043 mV, 0.065 ± 0.027 s, 0.278 ± 0.043 s, and 0.278 ± 0.043 s, respectively (Varshney et al. 2013).





Table 18.1

Electrocardiographic indices in Surti buffalo calves (Base-apex lead system)











































































ECG indices


Range


Mean ± S.E.


Median


Heart rate (bpm)


90–130


90.39 ± 3.44


90.0


P amplitude (mV)


0.1–0.35


0.195 ± 0.010


00.20


P duration (s)


0.04–0.07


0.0513 ± 0.0014


00.05


P-R segment (s)


0.011–0.16


0.11 ± 0.0558


00.12


P-R interval (s)


0.061–0.24


0.166 ± 0.056


00.165


QRS amplitude (mV)


0.45–1.750


0.877 ± 0.062


00.70


QRS duration (s)


0.04–00.08


0.051 ± 0.0017


00.05


ST segment (s)


0.08–0.36


0.167 ± 0.034


00.165


T amplitude (mV)


0.10–1.00


0.278 ± 0.043


00.020


T duration (s)


0.04–0.10


0. 0.065 ± 0.027


00.06


Q-T interval


0.20–0.50


0.284 ± 0.087


00.28


R-R interval (s)


0.40–1.36


0.671 ± 0.041


00.64


18.3 Electrocardiographic Indices in Holstein Crossbreds


Values of electrocardiographic indices in healthy Holstein crossbred calves are given in Table 18.2. Mean values for heart rate, “P” amplitude, “P” durations, “R” segment, “P-R” interval, “QRS” amplitude, “QRS” duration, “S-T segments” amplitude, “T” duration, “Q-T” interval, and “R-R” interval have been reported as 85.2 ± 4.23 bpm, 0.234 ± 0.031 mV, 0.05 ± 0.0024 s, 0.125 ± 0.025 s, 0.884 ± 0.06 mV, 0.054 ± 0.0001 s, 0.182 ± 0.038 s, 0.318 ± 0.088 mV, 0.069 ± 0.0037 s, and 0.308 ± 0.0017 s, respectively (Varshney 2018c). Electrocardiographic complexes in buffaloes and cows are almost of similar pattern.





Table 18.2

Electrocardiographic indices in Holstein crossbred calves (Base-apex lead system)

































































ECG indices


Range


Mean ± S.E.


Median


Heart rate (BPM)


60.0–140.0


85.2 ± 4.23


80.0


P amplitude (mV)


0.10–0.30


0.234 ± 0.031


00.2


P duration (s)


0.04–0.08


0.05 ± 0.002


0.02


P-R interval (s)


0.08–0.18


0.125 ± 0.025


0.12


S amplitude (mV)


0.20–1.70


0.884 ± 0.06


0.90


QRS duration (s)


0.04–0.08


0.054 ± 0.0001


0.06


S-T segment (s)


0.12–0.28


0.182 ± 0.038


0.20


T amplitude (mV)


0.1–0.6


0.318 ± 0.088


0.30


T duration (s)


0.04–0.12


0.069 ± 0.0037


0.08


Q-T interval (s)


0.24–0.39


0.308 ± 0.0017


0.32

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Jul 17, 2021 | Posted by in INTERNAL MEDICINE | Comments Off on in Ruminants

Full access? Get Clinical Tree

Get Clinical Tree app for offline access