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Chapter 18: Arrhythmias and Other Electrocardiographic Abnormalities 251
nans (Maisenbacher and Adin 2006) or transient third- Blömström-Lundqvist C, et al. ACC/AHA/ESC guidelines for the
degree AV block (Kellum and Stepien 2006) in cats, but management of patients with supraventricular arrhythmias—
J/Osborn waves have not been described. executive summary: A report of the American College of
Cardiology/American Heart Association task force on practice
guidelines and the European Society of Cardiology Committee for
U Wave Practice Guidelines and Policy Conferences (Writing Committee
to Develop Guidelines for the Management of Patients with
A very small wave following the T wave, notably in cases
Supraventricular Arrhythmias). Circulation 2003;108:1871–1909.
of severe hypokalemia, is called the U wave. It is noted Boothe HW, Clark DR, Merton DA. Cardiovascular effects of rapid
very infrequently in cats (Atkins 1991) even with severe infusion of crystalloid in the hypovolaemic cat. J Small An Pract
hypokalemia, perhaps at least in part due to the small 1985;26:477–489.
amplitude of feline ECG deflections in general. Aberrant Boyden PA, Tilley LP, Albala A, Liu SK, Fenoglio JJ, Wit AL.
repolarization of Purkinje fibers, the long action poten- Mechanisms for atrial arrhythmias associated with cardiomy-
tial of midmyocardial (M) cells, or delayed repolariza- opathy: A study of feline hearts with primary myocardial disease.
Circulation 1984;69:1036–1047.
tion in areas of the ventricle that undergo late mechanical Bright JM, Martin JM, Mama K. A retrospective evaluation of trans-
relaxation are mechanisms that have been proposed to thoracic biphasic electrical cardioversion for atrial fibrillation in
explain its existence (Mirvis and Goldberger 2008). dogs. J Vet Cardiol 2005;7:85–96.
Clinically in the cat, identification of U waves should The Cardiac Arrhythmia Suppression Trial II Investigators. Effect of
simply prompt confirmation of hypokalemia and appro- the antiarrhythmic agent moricizine on survival after myocardial
infarction. N Engl J Med 1992;327:227–233.
priate treatment of the electrolyte deficit. Costello MF, Drobatz KJ, Aronson LR, King LG. Underlying cause, Arrhythmias
pathophysiologic abnormalities, and response to treatment in cats
T Wave Alternans with septic peritonitis: 51 cases (1990–2001). J Am Vet Med Assoc
Abnormal ventricular repolarization may manifest as an 2004;225:897–902.
alteration in the appearance of the T wave. In one cat, Côté E. Electrocardiography and cardiac arrhythmias. In: Textbook
of Veterinary Internal Medicine, 7th ed., Ettinger SJ, Feldman
profound hypothermia (32°C [91°F]) produced marked EC, eds. St. Louis, Saunders Elsevier, 2010, 1159–1187.
prolongation of the QT interval (320 msec, compared to Côté E, Charuvastra E, Richter K. Event-based cardiac monitoring in
200 msec when the cat was subsequently normother- small animal practice. Comp Cont Ed Pract Vet 1999;21:1025–1033.
mic) and T wave alternans—a pattern of alternating tall Côté E, Harpster NK. Feline cardiac arrhythmias. In: Kirk’s Current
and wide versus narrow and short T waves (Maisenbacher Veterinary Therapy XIV, Bonagura JD, Twedt DC, eds. St. Louis,
Saunders Elsevier, 2009, 731–739.
and Adin 2006). These ECG abnormalities resolved with Côté E, Harpster NK, Laste NJ, MacDonald KA, Kittleson MD, Bond
correction of hypothermia. T wave alternans also has BR, Barrett KA, Ettinger SJ, Atkins CE. Atrial fibrillation in cats:
been documented in experimental cats undergoing elec- 50 cases (1979–2002). J Am Vet Med Assoc 2004;225:256–260.
trical stimulation of the stellate ganglion (Schwartz and Côté E, Jaeger R. Ventricular tachyarrhythmias in 106 cats: associated
Malliani 1975). T wave alternans, and more recently, structural cardiac disorders. J Vet Intern Med 2008;22:
1444–1446.
microvolt T wave alternans, is a negative prognostic Côté E, Laste NJ. Transvenous cardiac pacing. Clin Tech Small An
indicator in humans with coronary artery disease Pract 2000;15:165–176.
(greater risk of sudden cardiac death), but such an asso- Côté E, Manning AM, Emerson D, Laste NJ, Malakoff RL, Harpster
ciation is not recognized in the cat. NK. Assessment of the prevalence of heart murmurs in overtly
healthy cats. J Am Vet Med Assoc 2004;225:384–388.
REFERENCES Delacrétaz E. Supraventricular tachycardia. N Engl J Med
2006;354:1039–1051.
Boldface font indicates key references. DiBartola SP, Autran de Morais H. Disorders of potassium: hypoka-
Abbott JA. Heart rate and heart rate variability of healthy cats in home lemia and hyperkalemia. In: Fluid, Electrolyte, and Acid-Base
and hospital environments. J Fel Med Surg 2005;7:195–202. Disorders in Small Animal Practice, 3rd ed. St. Louis, Saunders,
Alings AM, Bouman LN. Electrophysiology of the ageing rabbit and 2006, 91–121.
cat sinoatrial node—A comparative study. Eur Heart J 1993;14: Diepstra G, Gonyea W, Mitchell JH. Cardiovascular response to static
1278–1288. exercise during selective autonomic blockade in the conscious cat.
Atkins CE. The role of noncardiac disease in the development and Circ Res 1980;47:530–535.
precipitation of heart failure. Vet Clin North Am Small An Pract Drobatz K, Hughes D. Concentration of ionized calcium in plasma
1991;21:1035–1080. from cats with urethral obstruction. J Am Vet Med Assoc
Atkins CE, Côté E, de Francesco TC, Maggio F, Davidson MG. 1997;211:1392–1395.
Prognosis in feline heartworm infection: Comparison to other Echt DS, Liebson PR, Mitchell LB, Peters RW, Obias-Manno D, Barker
cardiovascular diseases (abstract). Proceedings of the American AH, et al. Mortality and morbidity in patients receiving encainide,
Heartworm Society Symposium. Dallas, TX, 2001. flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial.
Berne RM. Cardiac nucleosides in hypoxia: Possible role in regulation N Engl J Med 1991;324:781–788.
of coronary blood flow. Am J Physiol 1963;204:317–322. Ettinger PO, Regan TJ, Oldewurtel HA. Hyperkalemia, cardiac con-
Berry CR, Lombard CW. ECG of the month. J Am Vet Med Assoc duction, and the electrocardiogram: A review. Am Heart J
1986;189:1542–1543. 1974:88:360.