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 25-28 September, 2018 | Singapore
The ends of the wire are brought across the cranial aspect of the tibia in a “figure of 8” pattern and then passed under the straight patellar tendon before being twisted tight. As for cerclage wire twisting technique, is important to insure that the two wire ends are correctly twisted around each other and not one around the other to form a “skip knot.”
As the wire is tightened its proximal loop engages on the protruding ends of the Kirschner wires. Each K. wire is than bent and cut leaving a hook of about 5 mm long that is rotated to fit snugly against the tibial tuberosity and insertion of the straight patellar tendon.
Although theoretically a twist should be placed in each side of the “figure of eight” to achieve uniform tension in the wire, adequate tightening is achieved with a single twist on just one side particularly in short tension band constructs.
A. Boswood1
1Royal Veterinary College, Clinical Science and Services, London, United Kingdom
How do we record an EKG and what gives rise to the observed impulses?
The diagnostic electrocardiogram (ECG or EKG) is recorded by the placement of electrodes at various points on a patient’s skin surface and then comparing the potentials recorded at those sites either with the potential recorded at another site (in the case of bipolar leads) or with a derived potential that is meant to represent the “average” potential of the patient in the case of unipolar leads.
In canine and feline patients the electrodes are usually placed on the limbs and the three main leads that are recorded are the limb leads that make up Einthoven’s triangle. Lead I is derived by comparing the potential between the two forelimbs, lead II by comparing the potential at the right forelimb with that of the left hindlimb and lead III by comparing the potential of the left forelimb with that of the left hindlimb. The deflections displayed in all leads are a consequence of the intrinsic electrical activity of the heart. They represent the potential differences created by the depolarisation and repolarisation of the heart and
by carefully characterising the different components of these deflections we can determine if the depolarisation and repolarisation are normal and indirectly derive some information about the size of the heart chambers and the metabolic status of the patient.
Normal depolarisation is initiated at the sino-atrial node and leads to a normal sequence of activation of atrial and then ventricular myocardial tissue. Potential differences between different parts of the heart are generated due to the transmembrane ionic fluxes that occur during depolarisation of the heart.
The pattern of depolarisation that happens under normal circumstances is initiated at the sino-atrial node. The wave of depolarisation initiated here is propagated throughout the remainder of the myocardium by rapid conduction through the specialised conducting tissues. The wave
is carried between atria and ventricles through the atrioventricular node. The normal pattern on an EKG is
· P-wave representing the atrial depolarisation
· PQ interval representing the delay in conduction between atria and ventricles caused by the slow con- duction at the AV node.
· QRS complex caused by depolarisation of the ventri- cles.
· T-wave caused by repolarisation of the ventricles.
   Fig 2:
Suggested Readings:
Roe SC.Mechanical comparison of cerclage wires:Introduction of the double- wrap/loop and loop/twist types, Vet Surg, 26:310-316,1997.
MacLaughlin RM. Internal fixation: Intramedullary pins, cerclage wires and interlocking nailes.Vet Clin North Am 29:1097-1116,1999.
AO Principles of Fracture Management in the Dog and Cat - Ann L Johnson John EF Houlton Rico Vannini
Thieme - 2005 by AO Publishing, Switzerland, Clavadelerstrasse, CH-7270 Davos Platz Distribution by Georg Thieme Verlag, R

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