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					Changing P wave polarity. Intermittent posterior internodal conduction.
Z Abedin and A R Geraci Chest 1976;70;792-795 DOI 10.1378/chest.70.6.792

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CHEST is the official journal of the American College of Chest Physicians. It has been published monthly since 1935. Copyright 1976 by the American College of Chest Physicians, 3300 Dundee Road, Northbrook, IL 60062. All rights reserved. No part of this article or PDF may be reproduced or distributed without the prior written permission of the copyright holder. (http://www.chestjournal.org/site/misc/reprints.xhtml) ISSN:0012-3692

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heart catheter. Br Heart J 35 335-642, 1973 6 Steele P, Davies H: The Swan-Ganz catheter in the cardiac laboratory. Br Heart J 35:647850, 1973 7 Jones SM, Miller GAH: Catheterization of the pulmonary artery in transposition of the peat arteries using a SwanGanz flow-directed catheter. Br Heart J 35:298-300, 1973 8 Kelly DT, Krovek LJ, Rowe RD: Double-Lumen flotation catheter for uses in complex congenital cardiao anomalies. Circulation 44: 910-913, 1971 9 Stranger P, Heymann MA, Hoffman JL, et al: Use of the Swan-Ganz catheter in cardiac catheterization of infants and children. Am Heart J 83:744754, 1972 10 Lapin ES, Mumy JA: Hemoptysis with flowdirected cardiac catheterization. JAMA 220: 1246, 1972 11 Chun GMH, Ellestad MH: Perforation of the pulmonary artery by Swan-Ganz catheter. N Engl J Med 284:10411042,1971 12 Golden MS, Pinder T Jr, Anderson WT, et al: Fatal pulmonary hemorrhage complicating use of a flow-directed balloon-tipped catheter in a patient receiving anticoagulant therapy. Am J Cardiol32:865-867, 1973 13 Geha DG, Davis NJ, Lappas DG: Persistent atrial arrhythmias associated with placement of a Swan-Ganz catheter. Anesthesiology 39:651653, 1973 14 Lipp H, O'Donoghue K, Resnekov L: Intracardiac knotting of a flowdirected balloon catheter. N Engl J Med 2 4 ,1971 8: m 15 Yorra FH, Oblath R, Juffe H, et al: Massive thrombosis associated with use of the Swan-Ganz catheter. Chest 65:682884,1974 16 Abernathy WS: Complete heart block caused by the Swan-Ganz catheter. Chest 65:349, 1974

spread in wave-like fashion from the sinoatrial node. Although Lewis was aware of the earlier work suggesting specialized internodal connections, his experiments did not prove a functional role for these pathways, which led him to believe they were not of electrophysiologic significance. Descriptions of rhythms associated with abnormal Pwave morphology were based on the wave-spreading theory proposed by Lewis;l however, this concept could not be substantiated by intracardiac pacing studies which translocated the pacing site but did not produce the expected P wave morphology based on the classic ~ wave-spread t h e ~ r y .Recent studies have considered the role of the specialized intra-atrial pathways and their functional significance in the production of normal and abnormal P wave morphologies.3 Spontaneous changes in P wave polarity have not been studied by intracardiac recordings in the intact human subject. The present case demonstrates changes in P wave polarity without any change in heart rate, suggesting an intermittent change in the internodal conduction rather than translocation of the pacing site.

Changing P Wave polarity*
Intermittent Posterior Internodal Conduction
Zainul Abedin, M.D.,Oa and Anthony R. Ceraci, M.D., F.C.C.P.t

A 65-year-old white woman was admitted for evaluation of retrosternal distress on exertion and an "abnormal" ECG. The rekosternal distress was relieved with rest. The blood pressure was 130/70 mrn Hg, and the pulse was 64 beats per minute and regular. There was a systolic ejection click and a grade 2 systolio ejection murmur. Findings from the remainder of the physical examination were normal. A chest xray film was unremarkable. The ECG showed a normal QRS pattern with no resting ST segment or T wave abnormalities ( Fig 1) . Spontaneous changes in P-wave morphology were observed without change in the bmic rate or P-R! interval. Studies of the altering P wave morphology were then performed.

Spontaneous changes of P-wave polarity without change in heart rate were noted on the r e d q electrocardiogram of a w e n t admitted because of chest pain. Intracardiac and His bnndle electrograms were compatible with a seqnence of activation horn high to low right atrium with both positive and negative P waves in lead aVR. The decrease in the P-His interval d positive P waves in lead aVR b consistent with selective conduction via the posterior internodal pathway.

Results were recorded on photographic paper on a ref corder (Electronics for Medicine DR 8 ) at a paper speed o 150 mm/sec with 0.1 second time lines. A standard tripolar His-bundle catheter3 was positioned across the tricuspid valve. A No. 4.5 French pacing catheters was inserted into the right atrium and coronary sinus from the right antecubital vein. Pacing and recording were performed with the pacing catheter, and recordings were obtained from the His bundle catheter in the usual fashion.
RESULTS

T

he P wave polarity in the normal surface electrocardiogram is generally positive in frontal-plane leads other than lead aVR. Deviations of the P-wave axis from the normal have been ascribed to translocation of the pacing site to areas remote from the sinoatrial node. This approach resulted from the original studies of Sir Thomas Lewis,' who proposed that atrial activation 'From the Department of Medicine, the Toledo Hospital and the Medical College of Ohio, Toledo. ''Resident in Medicine. +AssistantClinical Professor o Medicine. f Reprint requests: Dr. Geraci, 3939 Monroe, Tokdo 43606

With normal P wave polarity the P-His (P-H) interval was 129 msec, and the His-ventricle (H-V) time was 42 msec (Fig 2 and 3 ) . The values were similar in leads aVR and aVF, except for a slightly longer P-H interval due to earlier appreciation of the P wave activity in lead aVF. When positive P waves occurred in lead aVR, the PH interval shortened to 102 msec (Fig 4 ) . The H-V interval was unchanged. The sequence of activation was 3U.S. Catheter Corp., Glen Falls, NY. §Cordis Corp., Miami, Fla.

792 ABEDIN, GERACI

CHEST, 70: 6, DECEMBER, 1976

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FIGURE ElectromwdCgram. Sp0ntme-0~~ 1 . changes in P wave polarity ocau without change he& rate or P-Rinterval ( strips are continuous).

~I I

from high to low right atrium (LRA)at all times (Fig 3 and 4). The following measurements were obtained from the e1ectrogram.s with positive and negative P waves in lead aVR (Fig 3 and 4): P-LRA interval, 37 msec with negative P waves vs 60 msec with positive P waves; LRAH interval, 91 msec with negative P waves vs 42 msec with positive P waves; H-V interval, 42 msec both with negative and with positive P waves; and total P-V interval, 170 msec with negative P waves vs 144 msec with positive P waves.

Negative P waves in leads other than lead aVR can

occur by mechanisms such as exit of the sinus nodal
impulse via a different route than normal, conduction block in the specialized internodal pathways or actual translocation of the pacing site4 to the coronary sinus,.to the atrionodal junction, or to the left a t r i ~ m Trans.~ location of the pacing site (ectopic atrial pacemaker) is probably not the mechanism for the P wave changes seen in the present case. It is unlikely that an ectopic pacing site would possess an intrinsic rate similar to that of the sinus node. In addition, an ectopic atrial pacing site (be it coronary sinus, atrionodal junction, or left atrium) is associated with retrograde activation of the
F'ICURE 2. Lead aVR, coronary sinus electrode ( CS ) ,and HG bundle electrogram ( HBE ) . Normal negative P wave occurs in lead aVR; lower right atrial spike occurs before coronary sinus activity. CS is probably recording posterior left atrial activity and not potential at ostia of coronary sinus.

CHEST, 70: 6, DECEMBER, 1976

CHAN61N6 P WAVE POLARITY 793

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f

right atrial activity occurs before low ri&t atrial activity. P-H and H-V intervals are normal. right atrium when recorded with two or more intra-atrial electrodes. The sequence of activation observed proceeded from high to low right atrial recording sites at all times, irrespective of the P wave polarity in the frontal plane. This sequence of activation would be unlikely with an ectopic focus in one of the aforementioned locations unless the ectopic site was situated in the superior aspect of the right atrium. Theoretically, an ectopic atrial focus could be present, but this would suggest that both pacing sites are mutually protected6 and that a shift in the pacing focus occurs without a change in the heart rate. It is unlikely that two pacing sites can exist with identical rates and yet possess entrance block and provide mutual protection. Translocation of the pacing site is probably not the mechanism of the observed P wave changes. The presence of specialized pathways of atrial conduction and their influence on P-wave polarity has received experimental attention and may provide an explanation for the present observati~ns.T*~ Presumably, conduction occurs over the anterior internodal pathway in the normal state.O Conduction via the posterior internodal pathway may occur if conduction fails in the anterior or middle pathway. Failure to conduct may be due to structural disease in the usual pathway, but

Hs bundle electrogram ( HBE ) . With negative P waves, high i

FIGURE Lead aVR, bipolar high right atrium (HRA), and 3.

FIGURE Lead aVR, bipolar high right atrium ( HRA), and 4. His bundle electrogram ( HBE). With spontaneous change o f p wave polarity, high right atrialpotential pre& low u t atrial spike of HBE, consistent with activatim from high to low right a ~ u m presence of upright P waves in lead aML in Note shorter P-H inkwal

'

decremental conduction or unidirectional block could also have favored conduction via the posterior internodal tract. The longer P-LRA interval noted with upright P waves in lead aVR is most likely due to the longer length of the posterior internodal tract. The shorter P-Hinterval is a result of a decrease in the LRA-H interval. This decrease in LRA-H interval could be a result of conduction over the paranodal tract, to which all three tracts contribute fibers, or a result of entry of the posterior tract into the lower portion of the atrioventricular node."J The changes in the P-LRA and LRA-H intervals with positive P waves in lead aVR (Fig 3) suggest that conduction is occurring via the posterior internodal pathway. To produce two distinct P-wave morphologies, two pathways must be conducting intermittently. Although the potential for reentrant rhythms is possible with two functioning pathways, none has occurred to date. The subtle changes in the QRS morphology that occur with changes in atrial depolarizationn also suggest different pathways of conduction in the present case. This unique opportunity to record spontaneous atrial activity suggests that P wave polarity and morphology may have limited usefulness as predictors of the site of origin of atrial impulse formation.lZ

194 ABEDIW, GERACI

CHEST, 70: 6, DECEMBER, 1976
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REFERENCES
1 Lewis T: Lectures on the Heart. New York, Paul B Hoeber Co, 1915, pp 3-31 2 Waldo AL, Vitikainen KJ, Kaiser GA, et al: The P wave and P-R interval: Effect of the site of origin of atrial depolarization. Circulation 42: 653-671, 1970 3 James TN, Sherf L: Specialized tissue and preferential conduction in the atria of the heart. Am J Cardiol28:414427, 1971 4 Brody DA, Woolsey MD, Arzbaecher RC: Application of computer technique to the detection and analysis of spontaneous P wave variations. Circulation 36:359-371, 1967 5 Harris BC, Shaver JA, Gray S, et al: Left atrial rhythm: Experimental production in man. Circulation 37:10001014,1968 6 Schamroth L: Sinus parasystole. Am J Cardiol20:434-436, 1967

7 Emberson JW, Challice CE: Studies on the impulse conducting pathways in the atrium of mammalian heart. Am Heart J 79:653-687,1970 8 James TN: The connecting pathways between the SA node and AV node and between the right and left atrium in the human heart. Am Heart J 66:498-508,1963 9 Cohen J, Sherf D: Complete interatrial and intra-atrial block ( atrial dissociation). Am Heart J 70:23-24, 1965 10 Lipman BS, Massie E, Kleiger RE: Clinical Scalar Electrocardiography (6th ed). Chicago, Year Book Medical Publishers, 1972, pp 5-10 11 Sherf L James TN: QRS abnormalities in AV block: , Variations and their significance. In Schlant RC, Hurst JW ( eds ) : Advances in Electrocardiography. New York, Grune and Stratton, Inc, 1972 12 MacLean WA, Karp RB, Kouchoukos NT, et al: P waves during ectopic atrial rhythms in man. Circulation 52:426434,1975

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1977 Annual Meeting of the American Thoracic Society Invitation for American Thoracic Society Annual Meeting Abstracts
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CHEST, 70: 6, DECEMBER, 1976

CHANGING P WAVE POLARITY 795

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Changing P wave polarity. Intermittent posterior internodal conduction. Z Abedin and A R Geraci Chest 1976;70; 792-795 DOI 10.1378/chest.70.6.792 This information is current as of August 23, 2009
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