Electrocardiogram analysis of the normal unanesthetized green peafowl (Pavo muticus)

Normal Electrocardiographic Pattern in Conscious Healthy Domestic Geese (Anser anser)

The aim of this study was to describe the reference intervals of electrocardiographic patterns and values in conscious healthy domestic geese (Anser anser). Standard bipolar and augmented unipolar limb lead electrocardiograms with a direct writing electrocardiograph were recorded in 14 domestic geese. The durations of PR interval, QRS complex, ST and QT intervals, the net of the QRS complex, and the P and T amplitudes were determined at 50 mm/s and at 1 cm = 1 mV. The polarity waveform was examined. The mean electrical axis in the frontal plane was determined in leads II and III. Data are expressed as means and standard deviations. The mean (SD) heart rate was 153.8 (22.4) beats/min. The QRS complex was mainly negative in leads II and III; it was positive in the augmented vector right, augmented vector left, and augmented vector foot leads. The T wave was positive in leads II, III, and the augmented vector foot lead and was negative in the augmented vector right and left leads. The mean electrical axis ranged between -30° to -140°. Electrocardiogram recordings were well tolerated by the geese. The reference intervals provided here can be used to assist in the interpretation of electrocardiographic patterns in geese.

High heart rate associated early repolarization causes J-waves in both zebra finch and mouse

High heart rates are a feature of small endothermic—or warm‐blooded—mammals and birds. In small mammals, the QT interval is short, and local ventricular recordings reveal early repolarization that coincides with the J‐wave on the ECG, a positive deflection following the QRS complex. Early repolarization contributes to short QT‐intervals thereby enabling brief cardiac cycles and high heart rates. We therefore hypothesized high hearts rates associate with early repolarization and J‐waves on the ECG of endothermic birds. We tested this hypothesis by comparing isolated hearts of zebra finches and mice and recorded pseudo‐ECGs and optical action potentials (zebra finch, n = 8; mouse, n = 8). In both species, heart rate exceeded 300 beats per min, and total ventricular activation was fast (QRS < 10 ms). Ventricular activation progressed from the left to the right ventricle in zebra finch, whereas it progressed from apex‐to‐base in mouse. In both species, the early repolarization front followed the activation front, causing a positive J‐wave in the pseudo‐ECG. Inhibition of early repolarization by 4‐aminopyridine reduced J‐wave amplitude in both species. Action potential duration was similar between ventricles in zebra finch, whereas in mouse the left ventricular action potential was longer. Accordingly, late repolarization had opposite directions in zebra finch (left‐right) and mouse (right‐left). This caused a similar direction for the zebra finch J‐wave and T‐wave, whereas in the mouse they were discordant. Our findings demonstrate that early repolarization and the associated J‐wave may have evolved by convergence in association with high heart rates.

ELECTROCARDIOGRAM ANALYSIS OF THE GOLDEN ( CHRYSOLOPHUS PICTUS) AND SILVER ( LOPHURA NYCTHEMERA) PHEASANTS

The aim of this study was to describe normal electrocardiogram patterns and values in two species of conscious pheasants (golden and silver). The standard bipolar and augmented unipolar limb leads electrocardiograms were recorded in the birds. The wave forms were analyzed in all leads at 50 mm/sec and at 10 mm = 1 mV to determine PR, QRS, ST, and QT durations and P, net QRS complex, and T amplitudes. The polarity of each wave form was tabulated in all leads. The mean electrical axis for the frontal plane, calculated using leads II and III, was mostly negative in two species (-43 ± 28.0° in golden and -92 ± 10.0° in silver pheasant). The P wave was predominantly positive in most of the leads. The pattern of wave forms of the QRS complexes were different (Rs, QS, rS, R, RS, QR, qR). The T wave was almost positive in leads I, II, III, and aVF. The heart rates of the birds were mean (± SD) of 320 ± 36 beats/min (golden) and 314 ± 31 beats/min (silver). Description of normal electrocardiogram parameters will facilitate a better understanding of electrocardiogram changes of unhealthy birds.

Analysis of the Normal Electrocardiogram in Wild Rooks ( Corvus frugilegus )

To describe the normal electrocardiographic (ECG) patterns and values in unanesthetized rooks ( Corvus frugilegus ), standard bipolar (I, II, and III) and augmented unipolar limb (aVR, aVL, and aVF) lead ECGs were recorded from 10 clinically healthy wild rooks. Wave forms were analyzed in all leads at 50 mm/s and at 10 mm = 1 mV to determine PR, QRS, ST, and QT durations; the net QRS complex; and P and T amplitudes. The polarity of each waveform was tabulated in all leads. The mean electrical axis (MEA) for the frontal plane was counted by using leads II and III. The mean heart rate was 340 ± 18 beats/min. The P wave was mainly positive in the most leads. The dominant pattern of waveforms of the QRS complexes was QS in leads II, III, and aVF, whereas in leads aVR and aVL, the patterns were rS and R, respectively. The T wave was positive in leads II, III, aVF, and aVL and negative in lead aVR. The mean of the heart MEA was -93 ± 2.2. Interpretation of the ECG values and patterns in rooks may facilitate a better realization of ECG changes of abnormalities in this species.

Normal electrocardiogram patterns and values in Muscovy ducks (Cairina moschata)

To describe normal electrocardiographic parameters in conscious Muscovy ducks (Cairina moschata), standard bipolar (I, II, and III) and augmented unipolar limb (aVR, aVL, and aVF) lead electrocardiograms were recorded in 10 clinically healthy birds. Wave forms were analyzed in all leads at 50 mm/s and at 10 mm= 1 mV to determine PR, QRS, ST, QT durations; the net QRS complex; and P and T amplitudes. The polarity of each waveform was tabulated in all leads. The mean electrical axis (MEA) for the frontal plane was calculated by using leads II and III. The mean (SEM) heart rate calculated from lead II was 146.6 - 6.8 beats/min. The P wave was predominantly positive in all leads. The dominant pattern of waveforms of the QRS complexes was rS in leads II, III, and aVF, whereas, in leads aVR, and aVL, the pattern was R. The T wave was positive in leads II, III, and aVF and was negative in leads aVR and aVL. The mean (SEM) of the heart MEA was -91.2 2 1.8. The electrocardiographic values and patterns tabulated in these clinically normal Muscovy ducks should provide a means of comparison to aid in the diagnosis of pathologic abnormalities in this species.

Normal electrocardiogram of the laughing dove (Spilopelia senegalensis)

The aim of this study was to describe the normal electrocardiographic patterns and values in conscious laughing dove (Spilopelia senegalensis). The standard bipolar (I, II, and III) and augmented unipolar limb (aVR, aVL, and aVF) leads' electrocardiographs were recorded in 10 clinically healthy laughing doves. The wave forms were analyzed in all leads at 50 mm/sec and at 10 mm = 1 mV to determine PR, QRS, ST, and QT durations, the net QRS complex, and P and T amplitudes. The polarity of each waveform was tabulated in all leads. The mean electrical axis (MEA) for the frontal plane was calculated using standard bipolar leads II and III. The mean heart rate (calculated from the lead II) was 357 +/- 12.5 beats/min. The P wave was positive in all leads except for the aVR lead. The dominant pattern of waveforms for the QRS complexes was rS in leads II, III, aVR, and aVF, whereas in leads I and aVL, the patterns were R and Rs, respectively. The T wave was positive in leads II, III, aVF and negative in leads I, aVR, and aVL. The average value of the heart MEA was -89.7 +/- 1.30 degrees. The electrocardiogram values and patterns tabulated in these clinically normal laughing doves provide a means of comparison to aid in the diagnosis of pathologic abnormalities in this species.