RT Book, Section
A1 Michaud, Gregory F.
A1 Stevenson, William G.
A2 Jameson, J. Larry
A2 Fauci, Anthony S.
A2 Kasper, Dennis L.
A2 Hauser, Stephen L.
A2 Longo, Dan L.
A2 Loscalzo, Joseph
SR Print(0)
ID 1155973579
T1 Common Atrial Flutter, Macroreentrant, and Multifocal Atrial Tachycardias
T2 Harrison's Principles of Internal Medicine, 20e
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781259644016
LK accessmedicine.mhmedical.com/content.aspx?aid=1155973579
RD 2024/04/19
AB Macroreentrant  atrial  tachycardia  is  due  to  a  large  reentry  circuit,  often  associated  with  areas  of  scar  in  the  atria.  Common  or  typical  right  atrial  flutter  is  due  to  a  circuit  that  revolves  around  the  tricuspid  valve  annulus,  bounded  anteriorly  by  the  annulus  and  posteriorly  by  functional  conduction  block  in  the  crista  terminalis.  The  wavefront  passes  between  the  inferior  vena  cava  and  the  tricuspid  valve  annulus,  known  as  the  sub-Eustachian  or  cavotricuspid  isthmus,  where  it  is  susceptible  to  interruption  by  catheter  ablation.  Thus,  common  atrial  flutter  is  also  known  as  cavotricuspid  isthmus-dependent  atrial  flutter.  This  circuit  most  commonly  revolves  in  a  counterclockwise  direction  (as  viewed  looking  toward  the  tricuspid  annulus  from  the  ventricular  apex),  which  produces  the  characteristic  negative  sawtooth  flutter  waves  in  leads  II,  III,  and  aVF  and  positive  P  waves  in  lead  V1(Fig.  245-1).  When  the  direction  is  reversed,  clockwise  rotation  produces  the  opposite  P-wave  vector  in  those  leads.  The  atrial  rate  is  typically  240–300  beats/min  but  may  be  slower  in  the  presence  of  atrial  disease  or  antiarrhythmic  drugs.  It  often  conducts  to  the  ventricles  with  2:1  AV  block,  creating  a  regular  tachycardia  at  150  beats/min,  with  p  waves  that  may  be  difficult  to  discern.  Maneuvers  that  increase  AV  nodal  block  will  typically  expose  flutter  waves,  allowing  diagnosis.