**3. Attaching the holter monitor**

The Holter apparatus is a handheld device that runs tests and consists of an ECG recording unit that has conductors of electromagnetic waves coupled to the animal by adhesives or suction cups. The recording of the examination is decoded by a computer program that specifically allows the evaluation of cardiac rhythm throughout the recording period.

In order for the recorders to meet the standards required by the *American Heart Association*, they should be able to record undistorted signals of high and low frequency, between 0.05 and 100Hz. These systems are able to record the signal ST. The recording can be common on cassette or memory card (more usual today) that stores the fully digitized signals captured by the electrodes. The advantage of scanning equipment is to reduce the weight and size of the recorders and the elimination of mechanical parts such as motor and reduction system. The recording should be in two leads. Devices that record in three channels can replace the two channels monitors.

sign occurs, the device records the moments before, during and after the clinical signs which should be evaluated. The CER device is smaller and can be used for a week or more, but requires constant observation of the animal, although there are some devices that can

In humans, medicine is defined in three classes of indications to perform CE: Class I - there is a consensus that the CE is a useful tool and reliable examination, class II - CE is useful and reliable, but there was no consensus, class III – there is consensus that the CE is unnecessary. In all situations in which the role of CE is discussed, it should be taken in account the history and the physical examination of the patient, and the review of the usefulness of the test. The decision to conduct a CE examination and interpretation of their results cannot be

The major use of this examination in dogs and cats is to identify the type and degree of




In moments of bradycardia, usually myocytes specialized in electrical conduction, trigger stimulus that can result in repeated arrhythmias. Therefore, due to the fact that some arrhythmias begin in a moment of great parasympathetic stimulation, it is logical to think that in an examination that is performed for 24 hours, with the animal performing its daily activities, it would be superior to the classic ECG in which the animal is contained on a clinic table. However, the ECG provides a panoramic view of the heart in ten different views

The Holter apparatus is a handheld device that runs tests and consists of an ECG recording unit that has conductors of electromagnetic waves coupled to the animal by adhesives or suction cups. The recording of the examination is decoded by a computer program that specifically allows the evaluation of cardiac rhythm throughout the recording period.

In order for the recorders to meet the standards required by the *American Heart Association*, they should be able to record undistorted signals of high and low frequency, between 0.05 and 100Hz. These systems are able to record the signal ST. The recording can be common on cassette or memory card (more usual today) that stores the fully digitized signals captured by the electrodes. The advantage of scanning equipment is to reduce the weight and size of the recorders and the elimination of mechanical parts such as motor and reduction system. The recording should be in two leads. Devices that record in three channels can replace the


function as EC conventionally or as CER at the same time.

ataxia, even without previous history of heart disease.

breeds (mostly Doberman and Boxer).


(leads), not being replaced by the CE examination.

**3. Attaching the holter monitor** 

two channels monitors.

performed independently.

Being the main indications:

who had DCM.

cardiac arrhythmias.

The systems analysis should always allow classification of the forms of waves and broad interaction with the device analyst for corrections and to eliminate possible artifacts.

The two channels apparatus have five electrodes and the three channels have seven. When using two channels device, the electrodes are fixed to the skin on the chest of the animal, according to the Ware scheme (1998):

Channel 1 - White electrode (negative): the sixth right intercostal space, two fingers above the costochondral articulation;


Channel 2 - Brown electrode (negative): the sixth left intercostal space, two fingers above the costochondral articulation;


In equipment with four electrodes (Cardioflash® or Cardiolight®: www.cardios.com.br), the local standard ECG precordial examination can been adapted for CE as follows: position of red electrode in V2 place (sixth left intercostal space adjacent to the sternum), black in V4 (sixth left intercostal space in the costochondral junction location), orange electrode between black and red, and white electrode in the V1 position of conventional ECG (fifth right intercostal space near the sternum), as shown in figure 1.

Fig. 1. Left side of the figure - Animal with electrodes attached to the chest for the conduct of examination by equipment with four electrodes (See the text for more details). Note the shaved area with the setting of adhesives and the coupling of electrodes. Right side of the figure – Dog using cervical collar and being subjected to examination. Note that the device is packed in the side pocket of its waistcoat (arrows).

Continuous Electrocardiography in Dogs and Cats 145

Fig. 2. Graphics show the average of the mean HR at different times of day, observed in sedentary (S) and athlete (A) dogs of the German shepherd breed. Note that the two groups of dog exhibit the same trend to increase and decrease in mean HR over 24 hours, and lower

Monitoring with the CE for 24 hours is especially useful because it provides details of the patient's heart rhythm, the total number and type of abnormal complexes, as well as the specific time of the day when they occurred. The clinician can assess the animal's activities in the period of recording and correlate exam results with clinical signs manifested at every

The method of CE does the ECG recording for long periods and during the patient's daily activities. This allows us to observe spontaneous changes and those caused by activities or situations experienced by the patient's daily routine and, above all, make sure that the reported symptom related to whether or not an electrocardiographic changes. Symptoms that may be caused by changes in heart rhythm should occur often enough to be surprised while doing the recording of the ECG; however, the direct relationship is not always present

In the situation "a" it is impossible to establish any relationship and the examination should be repeated depending on the severity of the clinical suspicion, in "b", though symptoms do not occur, the type of arrhythmia observed may suggest a possible correlation with the sign mentioned above; in "c", discards the possibility of a relationship of symptoms with arrhythmia and another cause should be investigated, in "d", each case must be

The CE detects the same supraventricular arrhythmias than the ECG, however there are

heart rates were observed from three to six hours of the morning.

moment.

and can have situations like:

**4.3 Supraventricular arrhythmias** 

some considerations to be taken.

a. a) Without clinical signs and without arrhythmia b. b) Without clinical sign and with arrhythmia c. c) With clinical sign and without arrhythmia

d. d) With clinical sign and with arrhythmia, but no correlation.

individualized, because we have patients that fall in both "b" and "c".

**4.2 Indication of the CE to evaluate clinical signs related to arrhythmias** 

In the thoracic region, where the adhesive electrodes are positioned, there must be ample shaving, cleaning of the area with alcohol to remove the hair and skin oils. After the gel electrodes are fixed with adhesive tape, dry the skin (Figure 1) and it should be held with a protective bandage to prevent the electrodes to come off.

Later, you put on a denim jacket or something similar, which will remain on the animal during the exam. The CE device will be packaged in the side pocket of the jacket and the cables will remain protected (Figure 1).

There is the possibility of performing the examination without the use of waistcoat only conditioning the device with bandage. After placing the recording monitor, cervical or Elizabethan collar should be used to prevent dog bites and damages to the unit. In the literature, the use of cervical or Elizabethan collars did not influence the heart rate in healthy dogs (Cavalcanti et al., 2007). However, it is clear that some dogs tolerate the use of cervical collar better than the Elizabethan one.

The weight of the device and the size of the vest should be compatible with the size of the animal; cats should use smaller devices
