Right Atrial Stimulation

Transcription

1 Right trial Stimulation. 1n The Treatment of Supraventriular Tahyarrhythmias SYNOPSIS Pervenous eletrial stimulation of the right atrium was suessful in onverting 15 episodes of supraventriular tahyarrhythmia in 9 of 15 patients. This inluded 13 onversions of atrial flutter, one eah of atrial tahyardia and juntional tahyardia. The proedure was performed at the bedside, without ompliation', using intraardia eletrography to diret atheter position. Indiret evidene from this series supports all three proposed mehanisms for the onversion of atrial flutter by atrial stimulation: 1) interruption of a re-entry iruit, 2) introdution of an impulse in the atrial vulnerable period reating atrial fibrillation, and 3) overdrive suppression of a rapid firing etopi fous. The method has ertain advantages over C ardioversion: 1) there is less potential for serious post-onversion arrhythmias, 2) serum enzyme profiles are not altered, 3) onomitant digitalis therapy is possible, and 4) ontinuous intraardia eletrographi monitoring IS available w1th the potential for repeated onversions.. The development of intraardia eletrography has simplified the d1agnos1s of supraventriular tahyarrhythmias.' 2 However, only reently has the strategially plaed wire been used, not only for diagnosis but for the treatment of these arrhythmias In this report right atrial stimulation, using onventional and high rate paemakers will be desribed as a method for terminating supraventriular tahyarrhythmias as a bedside proedure. The mehanism of onversion of atrial flutter by atrial stimulation will be disussed in light of our results. Finally, atrial stimulation is proposed as an alternative method for the treatment of supraventriular arrhythmias. William C. Owens, M..,** and. Louise Kremkau, M..*** *From the ivision of Cardiology, epartment of Mediine University of Oregon Medial Shool Portland, Oregon **Oregon Heart ssoiation Researh Fellow ***ssistant Professor of Mediine Supported in part by a Program Projet Grant of the U.S. Publi Health Servie (HL-06336) Reprint requests: William C. Owens, M.. ivision of Cardiology University of Oregon Medial Shool 3181 S.W. Sam Jakson Park Road Portland, Oregon MTHOS N MTRILS Conversion of supraventriular arrhythmias by atrial stimulation was attempted in fifteen patients. Thirteen patients had atrial flutter, one patient had V juntional tahyardia and one patient had paroxysmal atrial tahyardia with variable V blok. In every patient the arrhythmia was thought to be of less than 72 hours duration. flow direted platinum tipped atheter* was passed to the high right atrium via a sublavian or arm vein. The atheter was positioned using intraardia eletrography without fluorosopy. portable hest film was obtained to guarantee that there was no looping of the wire in the right atrium. 18 JOURNL OF XTR-CORPORL TCHNOLOGY See Us at ooths 47 & 48-

2 TL 1 Charateristis of High Frequeny Paemaker Constant urrent squarewave llowable load: 0 to 1,000 ohms resistive or omplex impedane Output urrent: adjustable from 0 to 20 milliamps Pulse width: 1 milliseond Pulse rate: adjustable between 60 and 600 pulses per minute The high frequeny paemaker was designed and onstruted by Mr. William Temple of the Veterans dministration Hospital, Portland, Oregon. Figure 1: Conversion of atrial flutter diretly to sinus rhythm using slow right atrial stimulation. Lead II (panel ) and the right atrial eletrogram (panel ) demonstrate the rapid regular atrial ativity with a 4:1 V blok. In panel C stimulation is begun and after the fourth impulse*, a non-onduted "P" wave follows-. fter a juntional esape beat, paemaker indued atrial rhythm ours and sinus rhythm ontinues after the paer is turned off (panel ). The proedure was arried out at the bedside and preautions were taken to protet the patient from another eletrial soure that ould inadvertently ause ventriular fibrillation. C ardioverter and resusitation art were immediately available. The paing wire was usually left in plae following onversion for monitoring up to 72 hours. ll the patients had reeived therapeuti doses of digitalis. Initial stimulation was performed with a onventional paemaker** and in later ases with a speially designed high frequeny paemaker (Table 1 ). In all instanes stimulation was begun at a slow rate, impulses/min and low amperage (2m), while observing the surfae Lead II for ventriular apture. The rate was advaned slowly with onstant monitoring for hanges in rhythm. Subsequently the amperage was inreased to m. The average length of time for the proedure was thirty minutes, with a range of fifteen minutes to one and a half hours. In most instanes existing entral venous pressure atheters in the sublavian vein served as immediate avenues for the plaement of the stimulating wire, however anteubital basili veins and external jugular veins were also satisfatory in some ases. Tehnial problems arose in two patients in whom delays of about thirty minutes were experiened in obtaining a suitable venous route. There was one forty minute delay when diffiulty in positioning the atheter in the right atrium ourred. **Medtroni emand Paemaker 5840 L : ; i; it I MONITOR L i '... -~~ I 1i Hi:! ~ ; iii! i... i ~ i i i i....i.cc I I.. i~i i 1 ""':. i:ij( ' lliii...,;; I 'i,:., TIT ; ; i!il ij, i''. I >>2 I '''.. "' '"..,. I li,j i ll!iii! llll : 1[1/![ji lr 1 i b' j ~ If lf w r:j..!ih,, 1.r iii If i!l'l -H (::! w " [ I! I iii.. 'I[,. ll' 1 I I>' r Iii! I'" <;I i 'I 1i I I ti I " I i!i I'... [II ii :; ji I lit I.::J 1!. I ::!: I tltt.., iili!iii 'I,: ase I I""' 1[1' l'f:l::ll Ill. = mt:...'l"' 11n.II "" i.e' 2 ';;; i!j'!!,,. I Iii I I!!.. :r... iii :~ ; ~ It ii iir I 'V:II if... '" "'... :ili? ii 1 :1; IL ii1.. <i! :... L22 <>TIMU L, TION RTI;FCT iii!i::; ii... <I. t:, :TUTilf:'i II II I llil '.!Tf!!! 1 1- 'IV! I> i. I ' l~ ill - j ll 1+1. l t '~!' l;~ II' jl.:. i' t G 'lksl :il+ ". ;... SUMMR/

3 RSULTS 1 n a total of 15 patients there were 15 suessfu I onversions in 9 patients. Table 2 lists the pertinent data of the suessful onversions. In five patients atrial flutter was onverted diretly to sinus rhythm. Figure 1 is representative of two of these patients (ases 1 and 2) in whom the stimulating rate was slow, around 80/min. Prior to atrial stimulation in ase 2, C ardioversion at 50 watts seonds had produed atrial fibrillation, whih spontaneously reverted bak to atrial flutter. ~low atrial stimulation was suessful in extmguishing the flutter and establishing sinus rhythm. Rapid atrial stimulation at a rate of 600/min suessfully onverted the other three patients to sinus rhythm (ases 4, 7 and 9). One episode of atrial flutter was onverted to transient atrial fibrillation (ase 3). Figure 2 demonstrates slow right atrial stimulation, whih hanges the rhythm. to atrial fibrillation followed by spontaneous onvers1on to sinus rhythm in 15 minutes. One patient, with mitral stenosis and an enlarged left atrium (ase 6), was onverted from a~rial.flutter. to atrial fibrillation three times with rapid atnal st1mulat1on (fig. 3). ah episode of atrial flutter was assoiated with a rapid ventriular rate whih was diffiult to ontrol with digitalis. Rapid atrial stimulation, faster than the flutter rate (around 400/min), produed atrial apture. Figure 2: Lead 11 (panel ) and t.he right atri.al eletrogram (panel ) demonstrate atnal flutter w1th 2:1. V blok. Right atrial stimulation (panel C) onverts th1s to atrial fibrillation (panel ). Sinus rhythm ourred after 15 minutes and 0.2 mg ouabain. If the paemaker was slowed or turned off at this point, atrial flutter returned. When the rate was inreased to 600, atrial fibrillation developed with slowing of the ventriular rate. The patient was maintained in atrial fibrillation after adjustment of antiarrhythmia drugs. V juntional tahyardia was diagnosed by right atrial eletrography as seen in Figure 4 (ase 5). Slow right atrial stimulation onverted this rhythm to regular sinus rhythm after a brief episode of paker-indued V dissoiation. One patient had several supraventriular tahyarrhythmias (ase 8). He initially had paroxysmal atrial tayardia with varying first and seond degree V blok, as shown in Figure 5. The initial impression was that the arrhythmia was digitalis-indued. Rapid atrial stimulation initially onverted the PT to atrial fibrillation with slowing of the ventriular rate. dditional digitalis was given and the rhythm hanged to atrial flutter. Further atrial stimulation onverted the atrial flutter to atrial fibrillation four times, and digitalis was given to slow the ventriular rate to around 100. Sinus rhythm ensued two hours later. In 6 patients, all of whom had atrial flutter, right atrial stimulation was unsuessful in hanging the rhythm. No differene in diagnosis, mediation or tehnique distinguished these patients from those who had suessful onversions. In the suessful onversions, the rhythm was usually altered within the first two to three minutes of stimulation and there were no instanes in whih prolonged stimulation altered the rhythm. ll of the onversions ourred at less than 5 rn. ase 3 'F '....,..,...,... QRS I t : I~!. I. :'1 l.,.: Ia ' : : ~.... r -,~-:...,., '" :'.... I. : :: 1'1 : IT j:;;; ~ ""C ~ I " '""~'--' l I'.. ' 24 JOURNL OF XTR-CORPORL TCHNOLOGY

4 -~ - o II 8 Figure 3: Lead II (panel ) and right atrial eletrogram show atrial flutter with 2:1 V blok. Panel C demonstrates rapid stimulation with atrial apture in the first portion and onversion to atrial fibrillation in the later portion. oth rapid stimulation and atrial fibrillation (panel C, & ) demonstrate slowing of the ventriular rate. ISCUSSION The treatment of atrial flutter has traditionally entered around drug therapy and diret urrent ardiaversion. Cardioversion, however, is not without signifiant ompliations and side effets, espeially in the digitalized patient.'2, 3 In treating atrial flutter with digitalis, high doses are often required to slow the ventriular rate. While propranolol may be benefiial in slowing the ventriular rate, the myoardial depressant effets of the drug may be undesirable. trial stimulation offers several advantages over diret urrent ardioversion for the treatment of supraventriular tahyarrhythmias. No anesthesia or sedation is neessary and disomfort is onfined to venapunture. There is less potential for serious post-onversion arrhythmias sine the ventriualr myoardium is not diretly depolarized by the stimulus. igitalis withdrawal is not neessary to onversion and no serious post-onversion arrhythmias have been enountered. 3 _,, Continuous monitoring is available if the wire is left in position and there is the potential for repeated onversion. There is no distortion of the serum enzyme profile in monitoring for aute myoardial infartion.' 4 isadvantages of atrial stimulation inlude tehnial problems assoiated with vein entry and atheter manipulation whih oasionally may be time onsuming. Perutaneous sublavian atheterization is not without some risk, however in many of the patients in our series a entral venous atheter had previously been plaed for monitoring of pressure. trial stimulation in the small number of series in the literature is less effetive than diret urrent ardioversion. Our suess rate is onsistent with that reported in the literature ::tr : r'\ ii N;/;a ~li.iil: i;ji " I \0 ;;;,;:;. :;;: ;::;i;:;: ;: ase 6 ;::; :::::.1:::: ::i: 111.1! i ::: :'Jill:::::::.. :'' ~ :-,:, 11 r: r 'In' ii1 nil~ 'i... ::.. :I j :: iui i HI l! i l l' I i ll i ~~uj :::: :::: ::: 1.. :1 I r m:,,. :H: ::'' :::: '',, ::: ::: ~::; :1 i'li:!i. ::: :::: iii iii::: H lip ill. ttltt1tttttttt1ttt!tttj,f. i i'... : ;; : :... I :: :::: :;F ~;;: Ui: :;:: :;:; :::: :::; :o:: ;: t TJ!t.:t. i t i t t ~ j :,::.:.:::: "" ::::,... SUMMR/

5 Figure 4: Initial CG and the high superior vena ava eletrogram (panel ) show a regular supraventriular rhythm. In the right atrial eletrogram (panel ), the atrial spike is seen buried in the QRS, typial of V juntional tahyardia. Slow right atrial stimulation (panel C) onverted this arrhythmia to sinus rhythm (panel ) after a brief episode of paemaker indued V dissoiation. The greatest danger with this proedure is inadvertent paing of the right ventrile, whih ould ause serious ventriular arrhythmias. lthough fluorosopi positioning of the wire would be ideal, ritially ill patients may often experiene unneessary delay in preparation for fluorosopy equipment and personnel. urate positioning of the atheter in the right atrium is provided by the intraardia eletrogram. portable hest film is used to verify the atheter position. Stimulation is begun at a slow rate wathing for inadvertent right ventriular apture. arold has desribed three possible mehanisms for the termination of atrial flutter by atrial stimulation. 3 The first mehanism is that of interruption of a reentry iruit. urrer 15 and arold 16 have reported various supraventriular tahyarrhythmias whih an be initiated and terminated with a single impulse.impulses delivered to the atrium at a rate less than its intrinsi rate may fall at an appropriate time to blok a re-entry iruit, interrupt the arrhythmia and establish sinus rhythm. The onversion of atrial flutter diretly to sinus rhythm in two ases in our series with slow atrial stimulation is ompatable with this thesis. The proposed mehanism is the introdution of a single impulse in the atrial vulnerable period, produing an unstable rhythm suh as atrial fibrillation. In one patient of our series atrial fibrillation ourred with slow right atrial stimulation whih subsequently onverted to sinus rhythm, without further intervention. The third mehanism is overdrive suppression of a single, rapid-firing etopi fous. It would seem unlikely that slow atrial stimulation ould suppress or hange a rapid-firing etopi fous, however impulses at a rate higher than the intrinsi atrial rate ould overtake and suppress a rapid-firing fous. In one patient in our series (ase 6). atrial apture was evident at rates faster than the intrinsi atrial rate, however if the stimulation was stopped or slowed the flutter returned ase 5 i; H~1 1 : :...,,,~.. t::, >ill lj : L J:;..: : ::. :' :;;... I I J ' I '.. ' I :'- I.. k ". I 1:. Ill H N!; INITIL (ont.) 26 JOURNL OF XTR-CORPORL TCHNOLOGY

6 Figure 5: Initial GG, Lead II (panel ) shows the regular tahyarrhythmia in a patient taking 0.25 mg digoxin per day. The right atrial eletrogram (panel ) shows atrial tahyardia with first and seond degree V blok after 0.2 mg ouabain. Right atrial stimulation was arried out as digitalis exess was onsidered to be the etiology of the arrhythmia. However, following onversion to atrial fibrillation (panel C) the ventriular rate was rapid. The patient spontaneously onverted to atrial flutter (panel ) and rapid stimulation hanged the rhythm to atrial fibrillation four times. igitalis was given to slow the ventriular rate to 100. Sinus rhythm ourred in two hours. immediately. This is onsistent with a single rapidfiring fous whih ould be suppressed temporarily during faster stimulation. Rapid atrial stimulation may offer an advantage over onventional slow stimulation by inreasing the numerial possibility of a single impulse interrupting a re-entry iruit or falling in the atrial vulnerable period. In two patients in our series rapid atrial stimulation produed atrial fibrillation and in one of these patients, it was observed to be definitely dependent on the high rate stimulation (ase 6). In the three patients in whom atrial fibrillation was indued by atrial stimulation, two onverted to sinus rhythm without further intervention and in all ases the ventriular rate was redued during atrial fibrillation. The slowing of the ventriular rate with onset of atrial fibrillation or during rapid atrial stimulation due to onealed ondution in the V onduting system. The refratory period of the V nodal tissue is prolonged due to the inreased number of impulses reahing it. y inreasing the refratory period, fewer impulses are ompletely transmitted to the ventriles. Gosslein 17 found more onsistent suess using alternating urrent to onvert supraventriular tahyarrhythmias to atrial fibrillation. method of plaing an appropriately timed impulse to the atrium, as desribed by Haft 18, may produe a higher perentage of onversion to atrial fibrillation. s demonstrated in our series and others ' ' 9 & 11 atrial fibrillation is often an unstable rhythm and will often spontaneously onvert to sinus rhythm. trial stimulation in the onversion of supraventriular tahyarrhythmias is a new method that needs further linial trials and elaboration to judge its effetiveness. It offers an alternative method to the treatment of supraventriular tahyarrhythmias and has ertain advantages to the traditional avenues of treatment. ase 8 -~ i 'l.f'l'' 1 :! I I q:: II I; 11 1 II ;:r I J:r'l1 1: II ' II :, Iii IF.: r: 1 1:' "' l!i I I r I i l I I F II I) J il~ i r: IV i ill ~~~ I -1 - I - Iii 1 I' li SUMMR/

7 TL 2 Patients with Suessful Conversions Case ge/sex iagnoses Initial rrhythmia Final Rhythm Stimulation Rate (ppm)/m 77M Ishemi heart disease, periarditis trial flutter sinus 85/3 2 23M Mitral stenosis trial flutter sinus 80/ M Septi shok, adrenal insuffiieny trial flutter sinus 130/ M ute myoardial infartion, shok trial flutter sinus 600/ M ute myoardial infartion with V juntional sinus 95/2 ongestive heart failure tahyardia 6 49 M Mitral stenosis trial flutter atrial fibrillation 600/2 (3 times) 7 70 F Post-op abdominal aorti aneurysm, trial flutter sinus 600/4 ishemi heart disease 8 25M orti insuffiieny PT with blok sinus 600/2 & trial flutter 9 70 M Chroni obstrutive pulmonary disease, trial flutter sinus 600/4 pneumonia, ishemi heart disease 1. Friesen W: Right atrial eletrography. perutaneous, transvenous, bedside tehnique. Northwest Med 67: , Kimball JT, Killip T: simple bedside method for transvenous intraardia paing. mer Heart J 70:35-39, arold S, Linhart J: Reent advanes in the treatment of etopi tahyardias by eletrial paing. mer J. Cardiel 25: , Gulotta S, ronson : Cardioversion of atrial tahyardia and flutter by atrial stimulation. mer J Cardiel 40: , Haft J, Kosowsky, Lau S, et al: Termination of atrial flutter by rapid eletrial paing of the atrium. mer J Cardiel 20: , Hunt N, Cobb F, Waxman M, et al: Conversion of supraventriular tahyardias with atrial stimulation. Cirulation 38: , Lister J, Cohen L, Vernstein W, et al: Treatment of supraventriular tahyardia by atrial stimulation. Cirulation 38: , Massumi R, Kristin, Tawakkol ; Termination of reiproating tahyardia by atrial stimulation. Cirulation 36: , Zeft H, Cobb F, Waxman M, et al: Right atrial stimulation in the treatment of atrial flutter. nn Intern Med 70: , esanis RW: iagnosti and therapeuti uses of atrial paing. Cirulation 43: , Zipes P; The ontribution of artifiial paemaking to understanding the pathogenesis of arrhythmias. mer J Cardiel 28: , Rabbino M, Likoff, W, reifus LS; Compliations and limitations of diret-urrent ountershok. JM 190: , Kleiger R, Lown : Cardioversion and digitalis. Cirulation 33: , Kontinnen, Hupli V, Louhija, et al: Origin of elevated serum enzyme ativities after diret-urrent ountershok. New ng J Med 281: , urrer, Shoo R, Wellens H: The role of premature beats in the initiation and the termination of supraventriular tahyardia in the Wolff-Parkinson-White Syndrome. Cirulation 36: , arold S, Linhart J, Samet P, et al: Supraventriular tahyardia initiated and terminated by a single eletrial stimulus. mer J Cardiel 24:37-41, RFRNCS 17. Gosselin, Gulotta S, Keller W, t al: Treatment of supraventriular tahyardias by alternating urrent stimulation of the right atrium. Cirulation (suppl Ill) , Haft J, Lau S, Stein, et al: trial fibrillation produed by atrial stimulation. Cirulation 37:70-74, New Rays of Hope for ll Hearts 28 JOURNL OF XTR-CORPORL TCHNOLOGY