Page 246 - Feline Cardiology
P. 246

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.
   241   242   243   244   245   246   247   248   249   250   251