Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from British Heart Journal, 1970, 32, 46. Supraventricular tachycardia with AV block
Nabil El-Sherif From the Cardiology Department, Kasr El-Aini Faculty of Medicine, Cairo University, Egypt, U.A.R.
It is extremely difficult, even impossible - except in rare instances - to differentiate cases of par- oxysmal atrial tachycardia with block from A V junctional tachycardia with forward block but free retrograde conduction to the atria. These cases are collectively termed supraventricular tachy- cardia with block. The arrhythmia is not uncormmon and an incidence of I in 360 electrocardio- grams was found in the last 6-year period. Supraventricular tachycardia with block has a dynamic nature, and because it dependsprimarily on the electrocardiogram for its recognition a critical review of the salient cardiographic features is given. However, not uncommonly it needs to be differentiatedfrom a long list of other disorders of the heart beat. The relation of the arrhythmia to other atrial disorders is discussed, and the presence of supraventricular tachycardia with latent block is mentioned. Of the present series, 82 per cent were found to be precipitated by means that deplete body potas- siun in a digitalized patient suffering usually from an advanced cardiac disease. This group has a serious prognosis With 22 per cent mortality, but rapid intervention by discontinuing digitalis and diuretic measures and the administration of potassium and other antiarrhythmic drugs are usually effective. In I8 per cent of cases digitalis could not be blamed for the arrhythmia, and this group has a better prognosis, and digitalis may be beneficial in controlling the ventricular rate if heart failure is present. http://heart.bmj.com/ Though disorders of impulse formation and junctional tachycardia with forward conduc- impulse conduction are usually treated separ- tion disturbance in the presence of a normal ately in papers on the electrocardiogram they retrograde conduction to the atria. This type often show mutual dependence. Usually when resembles cases of paroxysmal atrial tachy- a rhythm disturbance comprises both dis- cardia with block except perhaps for the direc- orders the prognosis is less favourable. This tion of atrial activation, as judged by the in- is exemplified by cases of paroxysmal atrial scription of inverted P waves in diaphrag- tachycardia with AV block, long recognized matic surface leads. However, recently we on September 23, 2021 by guest. Protected copyright. as a serious complication of digitalis over- have learned to depend less on the direction dosage. Though the first description of a case of the P wave as an indication of the site of was that of Lewis (I909), few cases had been impulse formation. Inverted P waves have described until 1943 when two large series been seen in experimentally induced low atrial were published by Barker et al. and Decherd, extrasystoles and tachycardias (Prinzmetal et Herrmann, and Schwab. More recently, al., I952), while experimentally produced paroxysmal atrial tachycardia with block has retrograde atrial activation may produce, become more frequently described, and its against the rule, upright P waves in diaphrag- relation to digitalis overdosage was clarified matic surface leads (Moore et al., I967). by the extensive work of Lown and Levine (I958). However, much emphasis on the sub- In the presence of a single ectopic supraven- ject has obscured the fact that AV junctional tricular systole it may be possible to differen- tachycardia with or without block is an even tiate atrial from AV junctional origin, depend- more frequent manifestation of digitalis over- ing largely on the temporal relation between dosage (Pick, Langendorf, and Katz, I96I; the P and QRS. The situation becomes more Soffer, I96I; Castellanos and Lemberg, I963). difficult in the presence of paroxysmal tachy- At least 5 different types of AV junctional cardias initiated in the atria or AV junctional tachycardia with block have been described tissue. These are usually considered together (Pick et al., I96I); one of these is a case of AV under the term of paroxysmal supraventricu- lar tachycardia, since their clinical manifesta- Received I9 May 1969. tions and their response to exercise, carotid Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from Supraventricular tachycardia with AV block 47 sinus compression, and drugs are usually records showing supraventricular tachycardia with identical (Friedberg, I966). It is now becom- block were studied. In a total of 23,500 electro- ing extremely difficult, even impossible - ex- cardiograms 66 cases were found. Most of them in a instances as will be seen later - were studied and personally followed. In the few cept few instances where personal contact was lacking, to differentiate cases of atrial tachycardia with thorough review of the clinical and laboratory AV block from cases of AV junctional tachy- data was obtained. During the study, emphasis cardia with forward block and normal retro- was placed on the type of heart disease present grade conduction, simply because of loss of and details of the therapeutic measures employed, the fixed temporal relation between the P and especially the digitalis and diuretic regimen. The QRS, while the direction of the P wave offers onset and offset of the arrhythmia were recorded little help. The present work finds that such when possible. The course, duration, number of differentiation is in fact unwarranted, since the attacks, and measures instituted in the treatment aetiology, clinical picture, salient electrocar- were all included in the study. The electrocardio- grams were analysed for atrial and ventricular diographic features, and management are rates, configuration of the atrial complexes, PP practically the same. These cases can be col- cycles, type ofAV block, cardiographic manifesta- lectively termed supraventricular tachycardia tions of digitalis toxicity, and other associated with complete atrial capture and forward AV rhythm disturbances. block or simply supraventricular tachycardia with block. It should be emphasized here that Results other types of AV junctional tachycardia with block showing complete or incomplete AV Pertinent data in the 66 cases that fulfilled the dissociation, where the atria are basically con- diagnosis of supraventricular tachycardia with trolled by the sinus rhythm or atrial fibrilla- block are summarized in Tables 1-3. The ages tion, are not included in the term, since these cases present sufficiently characteristic elec- trocardiographic patterns of their own. FIG. I Supraventricular tachycardia with block showing varying degree of AV block. Material and methods Note that the multiple ectopic P waves in The electrocardiograms at Kasr El-Aini, Cairo record B arise from the same ectopic centre that later on discharges repeatedly. All records
University Hospitals, in the 6-year period from http://heart.bmj.com/ January i962 to January i968 were reviewed, and were obtained in one sitting. on September 23, 2021 by guest. Protected copyright.
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..-.:.. I ~~~...... k II -, r---,. r .._v-_i*'~~~~~~~~~~~~~~~~~~~~~~~. I Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from 48 Nabil El-Sherif of the patients ranged widely from i8 to 75 TABLE i Aetiological diagnosis in 66 cases years, with a mean of 38 years. More than half of supraventricular tachycardia with block of them were in an advanced stage of conges- tive failure. Digitalis was regarded as the Aetiology No. of patients aetiological factor in the development of the arrhythmia in 82 per cent, using the criteria Digitalis-induced Arrhythmia unrelatec of Lown, Wyatt, and Levine (I960). Clinical arrhythmia to digitalis signs of digitalis toxicity were usually lacking; Men Women Men Women however, electrocardiographic signs in the form of multifocal ventricular premature sys- Rheumatic heart disease 17 9 I 3 toles, ST, and T changes were frequently re- Hypertension 4 2 I I Coronary heart disease 7 I 4 corded. Usually, these patients were on a Cor pulmonale 6 2 maintenance dose of digitalis, and the arrhyth- Cardiomyopathy 2 2 mia developed after measures leading to ex- Atrial septal defect (post-operative) - I cessive loss of body potassium, usually an in- Chronic renal failure 2 - - tensive diuretic therapy. Total 38 i6 7 5 During the period of observation i2 pa- tients died, and all were cases of digitalis- (54) (I2) induced supraventricular tachycardia with block. However, out of these only 4 patients had died in spite of active measures for treat- ment of the arrhythmia. TABLE 2 Electrocardiographic characteristics in supraventricular tachycardia with block Discussion
Electrocardiographic features Rate/mim. <100 101-120 121-150 151-200 201-250 > 250 P Wave There is a definite, yet sometimes Atrial I 3 8 29 20 5 slight, change in the contour of the P wave Ventricular 39 24 3 - from the basic sinus P wave. This is particu- Type of AV block: 2: I 48 larly seen in records showing either the onset Wenckebach 2I http://heart.bmj.com/ or offset of the arrhythmia (Fig. i and 2). The complete 3 P waves were upright though sometimes varying 34 diminutive in the diaphragmatic surface leads Contour of P wave in diaphragmatic surface leads: in 76 per cent and inverted in 24 per cent of positive (sometimes diminutive) 50 the cases (Fig. 3). Though the contour of the negative i6 P wave is in no way a sure sign of the site of origin of the ectopic discharge, it seems from this work that supraventricular tachycardia on September 23, 2021 by guest. Protected copyright. with block arises much more frequently from the upper part of the atria near the sino-atrial TABLE 3 Therapeutic considerations in supra- node than from the lower atrial region and the ventricular tachycardia with block adjacent AV junctional tissue. As early as 1943, Barker et al. reported negative P waves in one-sixth of Therapeutic measure No. of No. of their cases of paroxysmal cases successful atrial tachycardia with block. Lown and reversions Levine (1958) stated that the site of origin of the ectopic focus in paroxysmal atrial tachy- Digitalis-induced arrhythmia cardia with block was potassium by mouth I0 8 most commonly in the potassium intravenously i8 17 upper part of the atrium near the sino-atrial procainamide 6 5 node. This criterion of positive P wave in antazohne 2 2 diaphragmatic surface leads was, however, phenytoin 2 2 rigidly followed in later descriptions of tachy- propranolol 4 4 cardia with block (Goldberg et al., i960), Total 42 38 probably actively excluding cases with nega- tive P waves on the basis of their presumed Arrhythmias unrelated to digitalis AV junctional procainamide 4 4 origin. On the other hand, some propranolol 2 2 authors included all cases with negative P digitalis 6 4 waves under the heterogeneous group of AV Total 12 10 junctional tachycardia with block (Pick et al., Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from Supraventrictilar tachycardia with AV block 49
I96I; Castellanos and Lemberg, I963). As already mentioned, the contour of the P wave is not a sure sign of the site of origin of the ectopic discharge. A positive P wave may arise eVR from retrograde activation of the atria and a negative P wave may arise not in the AV junc- tional tissue but in the lower part of the atria. Y | . ..-F--AIf9,...,---Ai -.. It is only in one condition that we become reasonably sure that the negative P wave arises from AV junctional tissue; this is seen in Fig. VL _ E t L 4 which shows an ectopic centre of discharge with an intrinsic rate of 200 beats a minute that sometimes shows 2: I exit block. When the centre discharges freely at a rate of 200, aVF ^9 there is a 2: I AV block, and we are faced with < {r ¢A Wf !1Am.n a supraventricular tachycardia with block v.t .u where it is impossible to tell whether the site of origin is in the lower atrial or AV junctional Vi I I 11- regions. when a 2:I exit block i i i I i J i I However, 4 .., -{ develops we get an arrhythmia similar to what i... has been termed 'non-paroxysmal nodal tachycardia' by Pick and Dominguez (I957). V3 Here the AV junctional origin could be sug- gested depending on the temporal relation of the P following the QRS. In fact, exit block of an AV junctional ectopic centre, as shown here, is rare. We have found only 3 reported cases of a similar condition, where exit block was shown in cases of paroxysmal atrial tachy- cardia (Calviino, Azan, and Castellanos, I957; Phibbs, I963; Dressler, Jonas, and Javier, http://heart.bmj.com/ 1966). Cases of AV junctional arrhythmia 5 3 5 * I I described as showing exit block (Pick et al., r I96I; Castellanos and Lemberg, I963; Pick and Langendorf, I968) are in fact wrongly named. All these cases are associated with atrial fibrillation, and usually a complete block exists between the fibrillating atria and the AV junctional centre, while what is called FIG. 2 The dynamic nature of the arrhyth- on September 23, 2021 by guest. Protected copyright. an exit block represents simply a form of for- mia was fully shown during the routine ward block of a varying degree and does not recording of the electrocardiogram by a deserve the term of exit block as classically technician. The whole procedure usually took 3-4 minutes during which several short. understood. paroxysms of supraventricular tachycardia Atrial rate The rate of discharge of the with varying degree of AV block were recorded, ectopic pacemaker in supraventricular tachy- sometimes initiated by a premature atrial cardia with block shows a wide range. The systole (VI). highest rate recorded in this series was 295 beats a minute and the lowest rate in which the ectopic centre was still dominant was 72 atrial flutter at the high rate levels, and be- (Fig. 5). This is quite a slow rate for an ectopic tween it and sinus tachycardia or even normal atrial focus, and can only be explained by sinus rhythm at the low rate levels; this makes assuming a certain degree of depression of the it hazardous to depend solely on the atrial sino-atrial node. Rates as high as 400 (Simon- rate for their differentiation. son and Berman, I95I) and as low as io6 (Lown et al., I960) have been reported. How- PP interval In one-third of our cases the ever, in 86 per cent of the present series the PP cycles varied in their duration, the varia- atrial rate ranged between I20-250. It appears tion ranging from o-oI to 0X22 of a second that there is a significant overlap between (Fig. 6 and 7B). Half of the cases of Lown supraventricular tachycardia with block and et al. (I96o) showed variations of up to o0i2 4 Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from So Nabil El-Sherif , ¢, r r > : j
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FIG. 3 Supraventricular tachycardia with block showing inverted P waves in diaphragmatic surface leads. The blocked P waves are barely discernible; however, carotid sinus compression (CSC) gives rise to an increased degree of AV block and the atrial mechanism can easily be shown. s; http://heart.bmj.com/
of a second. This phenomenon has various tachycardia with block and atrial flutter can explanations: a commonly acceptable view be made by the presence of isoelectric inter- is the negative chronotropic effect of the ven- vals between P waves. On the other hand, tricular systole (Rosenbaum and Lepeschkin, Lown et al. (I960) think that rapid paroxys- I955). Classical paroxysmal supraventricular mal atrial tachycardia with block and slow atrial on tachycardia and flutter, the other flutter usually retains the PP baseline charac- on September 23, 2021 by guest. Protected copyright. hand, are characterized by a regular PP cycle teristics. In our experience it is only the second length. half of this view that holds true. While it is practically always possible in the presence of PP baseline An isoelectric baseline of o0o4 atrial rates below 200 to differentiate supra- sec. or more in every lead including the oeso- ventricular tachycardia with block from atrial phageal leads is considered a sine qua non in flutter, it is quite possible that above this rate supraventricular tachycardia with block, while - and especially above 250 beats a minute - the atrial flutter is characterized by an undulating decision concerning the presence or absence baseline in one or more leads. Prinzmetal et al. of an isoelectric interval may be difficult to (i95i) suggested that the undulating appear- make. There is always the subject of inter- ance of atrial flutter was due to the combina- individual and intraindividual variations in tion of ectopic P waves and the oppositely interpretation (Prinzmetal et al., I952; Ep- directed Ta waves. The more rapid the atrial stein et al., I96I; Caceres, I963). rate, the larger the Ta wave. Rosner (I964) suggested that it was possible for paroxysmal A V response All types of AV block from first atrial tachycardia with block associated with degree to complete were recorded, and in very fast atrial rates to show continuous base- many cases there was a shift from one type to line activity as a result of atrial repolarization another (Fig. i and 2). The predominant type becoming electrically more prominent. Ken- of AV heart block was, however, second de- namer and Prinzmetal (I954) have denied that gree AV block, frequently as sustained 2:1 the differentiation between paroxysmal atrial block with the sporadic Wenckebach's phe- Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from Supraventricular tachycardia with AV block i
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FIG. 4 Supraventricular tachycardia with exit block and double supraventricular tachycardias. Record A shows the development of AVjunctional tachycardia with inverted P waves in lead II after the QRS complexes simulating terminal S waves. Record B shows the release of a 2:I exit block giving rise to a supraventricular tachycardia with A V block; this is continued in record C. Record D shows a short paroxysm of tachycardia from the same atrial focus giving premature atrial systoles marked X above. on September 23, 2021 by guest. Protected copyright. nomenon. Vagal stimulation and carotid sinus mentioned during the discussion of the PP compression usually increase the degree of baseline characteristics. Four patients in the AV block but have no effect on the atrial rate present series have shown an increase in the (Fig. 3 and 8). In a few instances pseudo- rate of discharge of the ectopic supraventricu- bigeminy was shown (Fig. 8). This uncom- lar focus, with loss of the isoelectric baseline mon type of AV conduction was originally characteristics, either shortly after successful described in atrial flutter (Basoain-Santander, therapeutic reversion of supraventricular Pick, and Langendorf, 1950) but was not tachycardia with block (Fig. 7c) or in the wake previously reported in supraventricular tachy- of increase of the digitalis dosage and inten- cardia with block. It is explained by the pre- sive diuretic therapy (Fig. 5). Whether these sence of two levels of block in the AV junc- cases represent instances of rapid supra- tional tissue, a 2:I conduction ratio in the ventricular tachycardia with block or atrial upper region of the AV junction, and a 3:2 flutter is difficult to tell. Rosner (I964) called conduction ratio in the lower region. those cases, consisting primarily of rapid atrial activity but without any special appearance of Supraventricular tachycardia with block the baseline or atrial wave form, 'atrial tachy- and other atrial arrhythmias systole with block', and this has been taken The relation between supraventricular tachy- to favour the view that there is a continuum cardia with block and atrial flutter has been between supraventricular tachycardia and Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from 52 Nail El-Sherif
A V. tsc _VIB--A ~ CS 2 Vi r 3 - Th reors une B .'sho suraenriulr tahcri wit AV blc an-te seune of poasu infusion ..Nt... tha thX|;e siu rhth bea to sho in th fis hal of reor at a http://heart.bmj.com/ rate which is higher than that of the ectopic centre in the second half of the record. The ectopic centre was still dominant at a rate of 72 a minute (record 6). Record C was obtained shortly before the death of the patient, who was again under digitalis; it shows an atrial rate of 250 a minute and no PP isoelectric intervals. on September 23, 2021 by guest. Protected copyright. atrial flutter, with an intermediate zone that digitalis-induced atrial flutter is a rarity defies exact differentiation. The present work (Delman and Stein, 1964). cannotVI prove or disprove this view. However, The mechanism preceding the onset of weFI.thinkRecordthat in thesehwscasessupraventriuathe establishmenttacyadawithsupraventricularlatI FIG. 6 Supraventricular tachycardia with bloch showing variable PP cycle lengths. t.. t ... 4S s43!4342142 41J'bt61 ~47501447 5 7147[474247 424I.4|1I55 AQ'49 !52'~4515 50 i;4848482!48! 47,414 44444243i$2'.43, X42:6It6 1454 Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from Supraventricular tachycardia with A V block 53 -. :1 :. .. !:.-;.... I , AA -- 1- . -~~~~~~~t U1 LoL iL uA. k 1- i h .wF. 1w.. V~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~------ ~~~~~Ilr¼tnhj KiLI*....~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ILK~~... 4 -4~~~~~~~~~~~~~~~~ FI.Spavnticlr acycriawih lckan aralflttrRcodAtaken.on adisinhoesnu hyhmad ulioclvenrclrpeauessoe.Rcr obtained4days later when the patient~-A-.wasiiaiedsoeurvnriua-ahcriul withblock and varying~~~~~...... PPccelnts.h etiua rm tr ytlshdicesdi http://heart.bmj.com/ FIG. 8 Supraventricular tachycardia showingltwo levelsroflAfVblock..Viacshowsaaformo o psedobigemionyshwhedsnsreythemlongdRcylifclsarenotrdoublerthemshortRRycycles. Thiscouldbe exinedbyocassumaring the presene ofgts2TlevelstofcblocrithemAtuVjunctionealtissue.sdi nubrI ihodn iiai n h diitaino oalVRasu rsoe h snsryh on September 23, 2021 by guest. Protected copyright. a VI I I~~~~~~~~~ aVF& YIb~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I0a csc ...... Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from 54 Nabil El-Sherif Vi~~~~~~~~~~~~~~~~~~~~~~~~~~ B 1. - 248 244, 1+-. ~~486=243x 2 (cont): 244 246 - FIG. 9 Supraventricular tachycardia with block on top of chronic atrial fibrillation. Record A shows the development of supraventricular tachycardia with block in a patient known to have chronic atrial fibrillation. Withholding digitalis and the administration of propranolol resulted in re-establishment of atrial fibrillation (record B). It is interesting to observe that propranolol failed to abolish the ventricular parasystolic focus present but slowed down its intrinsic rhythm. FB represents fusion beats. rhythm, this was not our experience where re- by an increase in atrial rate with an alteration was in P wave and differs from establishment of atrial fibrillation noticed contour, supra- http://heart.bmj.com/ after control of the arrhythmia (Fig. 9). ventricular tachycardia with overt block in It is to be stressed here that when supraven- that the PP interval is normal and that AV tricular tachycardia with block develops on block is induced only by carotid sinus com- top of atrial fibrillation, the atria stop fibrillat- pression (Bernstein and Stanzler, 1966) ing and begin to contract rhythmically in re- and/or digitalization. This arrhythmia was sponse to the ectopic focus. This differs from originally described by Lown and Levine the admittedly more frequent manifestation (i958) as a stage during the evolution and of digitalis where enhancement of an recession of paroxysmal atrial tachycardia with toxidcity on September 23, 2021 by guest. Protected copyright. AV junctional pacemaker develops while an block. However, this period as described by area of block between the fibriltngara and Lown and Levine (i958) was brief, which the-~ectopic centre is present. could be explained by the rapid nature of the The occurrence of 2 supraventricular pace- experiments undertaken (Bemnstein and Stanz- makers competing for the atria was occasion- ler, 1966). It is possible for this stage to be ally observed as a transient phenomenon dur- prolonged if there is a gradual digitalis over- ing the evolution of the arrhythmia (Fig. 4). dosage or potassiumn depletion. One of these Usually one of the pacemakers is ill sustained, patients was noticed by Lown and Levine and this may explain why this phenomenon (i958), and 2 more cases were later described of 2 supraventricular pacemakers both cap- (Bernstein and Stanzler, 1966). One of our turing the atria was rarely recorded (Chung cases helped to show classically this type of and Thomas, 1965). This differs from the arrhythmia (Fig. 5). This was a case of coron- more frequent situation of double AV junc- ary heart disease receiving combined digitalis tional pacemakers, the upper one capturing and diuretic therapy for congestive failure, the atria while the lower one controls the ven- but the heart rate failed to slow down. An tricles, producing a complete or incomplete electrocardiogram recorded one week after atrioventricular dissociation (Pick et al., i96i; admission showed an atrial rate Of Io5 a Castellanos and Lemberg, i963). minute and a change in the contour of the P Lastly, the presence of a supraventricular wave which was difficult to explain. A trial to tachycardia with latent AV block was rarely slow down the heart rate by carotid sinus mentioned. This arrhythmia is characterized compression gave rise to AV block with little Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from Supraventricular tachycardia with AV block 55 effect on the atrial rate. The significance of Prognosis these changes was not grasped at that time, The prognosis in digitalis-induced paroxys- and more digitalis was given. However, mal atrial tachycardia with block was con- clinical irregularity was observed in the pulse sidered serious. The reported mortality rate and an electrocardiogram I0 days later showed varied from 28 per cent (Freiermuth and Jick, supraventricular tachycardia with AV block 1958) tO 58 per cent (Nadas, Rudolph, and and an atrial rate of I90 a minute. The contour Reinhold, I953). This is undoubtedly related of the P waves was the same as that observed to the underlying serious heart disease (Lown in the previous record which was now correct- et al., I960). It seems unlikely that the ly interpreted as showing supraventricular arrhythmia itself is directly detrimental to the tachycardia with latent block. When digitalis cardiac function and cardiac output (Gold- was stopped and K infusion started the atrial berg et al., I960). In the present series the rate regressed and sinus rhythm was estab- mortality in the digitalis-induced supraven- lished. It was interesting to observe that the tricular tachycardia with block was relatively ectopic centre remained dominant at an atrial high (22%). However, most of the cases died rate of 72/min. either because the arrhythmia was not sus- Apparently these cases are relatively rare; pected, and therefore no specific management however, recognition of their occasional rela- was undertaken, or because it was misdiag- tion to a lesser degree of digitalis toxicity is nosed, usually as atrial flutter, and digitalis important so that the more serious conse- was continued. Therefore, out of 42 cases of quences of further digitalis administration or the digitalis-induced arrhythmia receiving of potassium loss can be avoided. specific treatment, only 4 died during the period of observation (9%). On the other hand, the prognosis was excellent in the minor group unrelated to digitalis, with no single Diagnosis fatality during the observation period. As a rule, the diagnosis of supraventricular tachycardia with block depends essentially on Therapy the electrocardiogram, but even the tracing When the arrhythmia is due to digitalis, with- is sometimes missed or confused with other holding the drug may suffice by itself, but http://heart.bmj.com/ arrhythmias. This is probably the result of frequently a potassium-losing state is present the dynamic nature of the arrhythmia, and and potassium has to be given. There are in hence the varying phases that it may assume general two main routes for severe potassium in its development or recession. The main depletion, namely intestinal and renal, of difficulty will arise from failure of recognition which the renal loss through the indiscrimin- of the atrial activity either because these are ate use of diuretics is the most important. diminutive in the conventional leads taken But even potassium loss through haemodia- or because of superimposition of some or all lysis has sometimes been implicated (Lown on September 23, 2021 by guest. Protected copyright. of atrial waves on the QRS-T complexes. et al., I953). Either the oral or intravenous This difficulty will be accentuated in the routes may be chosen. Usually the atrial rate presence of a varying degree of AV block. shows gradual slowing before reversion to Sinus rhythm, sinus tachycardia, paroxysmal sinus rhythm and sometimes I: i conduction, supraventricular tachycardia, atrial flutter, with paradoxical increase of the ventricular atrial fibrillation, and ventricular tachycardia rate (Fig. 5). If potassium is contraindicated may enter into the differential diagnosis at or ineffective, other antiarrhythmic drugs can one time or another. be used. Procainamide, antazoline, phenytoin, Though the use of carotid sinus compres- and propranilol have all been tried with suc- sion or right chest leads is sometimes highly cess in the present series (Table 3). A case effective in the diagnosis by clarifying the report of the successful use of DC shock after atrial mechanism, the best way of unravelling failure of other measures was given by Cor- the atrial activity is by the oesophageal win, Klein, and Friedberg (I963). electrode (El Sherif, El-Ramli, and Sorour, On the other hand, when the arrhythmia is I969), (Fig. 4). unrelated to digitalis the various antiarrhyth- No essential electrocardiographic differ- mic drugs can be tried. More important is the ences were found between cases of digitalis- fact that digitalis can be successfully used. induced supraventricular tachycardia with The aim of digitalization is usually the con- block and those unrelated to digitalis. This trol of heart failure and/or the rapid ventricu- contrasts with previous claims (Oram, Resne- lar rate. Digitalis was given to 6 patients in kov, and Davies, I96o). the present series, and in all of them it suc- Br Heart J: first published as 10.1136/hrt.32.1.46 on 1 January 1970. Downloaded from 56 Nabil El-Sherif cessfully controlled the failure and slowed the Goldberg, L. M., Bristow, J. D., Parker, B. M., and Ritzmann, L. W. (I960). Paroxysmal atrial tachy- ventricular response. The arrhythmia was cardia with atrioventricular block; its frequent seen to disappear after the control of failure association with chronic pulmonary disease. Circu- in 4 of them while they were still under digi- lation, 21, 499. talis. The beneficial role of digitalis in Kennamer, R., and Prinzmetal, M. (1954). The cardiac atrial with block not arrhythmias. New England J7ournal of Medicine, paroxysmal tachycardia 250, 509. induced by digitalis was observed as early as Lewis, T. (I909). Paroxysmal tachycardia. Heart, I, 43. 1943 by Barker et al., and was later stressed Lown, B., and Levine, H. D. (I958). Atrial Arrhyth- by Morgan and Breneman (I962). mias, Digitalis and Potassium. Landsberger Medical Books, New York. -, Wyatt, N. F., Crocker, A. T., Goodale, W. T., and Levine, S. A. (1953). Interrelationship of digitalis References and potassium in auricular tachycardia with block. Barker, P. S., Wilson, F. N., Johnston, F. D., and American Heart Journal, 45, 589. Wishart, S. W. (I943). Auricular paroxysmal tachy- -,- , and Levine, H. D. (I960). Paroxysmal cardia with auriculoventricular block. American atrial tachycardia with block. Circulation, 21, I29. Heart Journal, 25, 765. Moore, E. N., Jomain, S. L., Stuckey, J. H., Buchanan, Basoain-Santander, M., Pick, A., and Langendorf, R. J. W., and Hoffman, B. F. (1967). Studies on ecto- (I950). AV conduction in auricular flutter. Circu- pic atrial rhythms in dogs. American Journal of lation, 2, 604. Cardiology, I9, 676. Bernstein, R. B., and Stanzler, R. M. (1966). Paroxys- Morgan, W. L., and Breneman, G. M. (I962). Atrial mal atrial tachycardia with latent block. Archives tachycardia with block treated with digitalis. of Internal Medicine, II8, 154. Circulation, 25, 787. Caceres, C. A. (I963). A basis for observer variation in Nadas, A. S., Rudolph, A. M., and Reinhold, J. D. L. electrocardiographic interpretation. Prog,ress in (I953). The use of digitalis in infants and children. Cardiovascular Disease, 5, 521. A clinical study of patients in congestive heart Calvinlo, J. M., Azan, L., and Castellanos, A., Jr. failure. New England Journal of Medicine, 248, 98. (I957). Paroxysmal tachycardia with 2: i exit block. Oram, S., Resnekov, L., and Davies, P. (I960). Digi- American Heart Journal, 54, 444. talis as a cause of paroxysmal atrial tachycardia with Castellanos, A., Jr., and Lemberg, J. (I963). The rela- atrioventricular block. British Medical Journal, 2, tionship between digitalis and A-V nodal tachy- 1402. cardia with block. American Heart_Journal, 66, 605. Phibbs, B. (I963). Paroxysmal atrial tachycardia with Chung, K. Y., and Thomas, J. (I965). Unusual form block around the ectopic pacemaker. Circulation, of digitalis-induced double atrial tachycardia. 28, 949. American Heart Journal, 70, 394. Pick, A., and Dominguez, P. (I957). Nonparoxysmal Corwin, N. D., Klein, M. J., and Friedberg, C. K. A-V nodal tachycardia. Circulation, I6, I022. (I963). Countershock conversion of digitalis- , and Langendorf, R. (I968). Recent advances in http://heart.bmj.com/ associated paroxysmal atrial tachycardia with block. the differential diagnosis ofA-V junctional arrhyth- American Heart Journal, 66, 804. mias. American Heart_Journal, 76, 553. Decherd, G. M., Jr., Herrmann, G. R., and Schwab, - , - , and Katz, L. N. (I96I). A-V nodal tachy- E. H. (1943). Paroxysmal supraventricular tachy- cardia with block. Circulation, 24, 12. cardia with A-V block. American Heart_Journal, z6, Prin7metal, M., Corday, E., Brill, I. C., Oblath, R. W., 446. and Kruger, H. E. (1952). The Auricular Arrhyth- Delman, A. J., and Stein, E. (1964). Atrial flutter mias. Charles C. Thomas, Springfield, Illnois. secondary to digitalis toxicity. Report of 3 cases -, Oblath, R. W., Kruger, H. E., Brill, I. C., and review of the literature. Circulation, 29, 593. Fields, J., Kennamer, R., Osborne, J. A., Smith, Dressler, W., Jonas, S., and Javier, R. (I966). Paroxys- L. A., Sellers, A. L., Flieg, W., and Finston, E. on September 23, 2021 by guest. Protected copyright. mal atrial tachycardia with exit block. Circulation, (195i). Auricular flutter. American_Journal ofMedi- 34, 752. cine, II, 410. El Sherif, N., El-Ramli, Z., and Sorour, A. H. (I969). Rosenbaum, M. B., and Lepeschkin, E. (I955). The Oesophageal electrocardiography in the study of effect of ventricular systole on auricular rhythm in cardiac arrhythmias. British HeartJournal, 31, 414. atrioventricular block. Circulation, II, 240. Epstein, F. H., Doyle, J. T., Pollack, A. A., Pollack, Rosner, S. W. (I964). Atrial tachysystole with block. H., Robb, G. P., and Simonson, E. (I96I). Obser- Circulation, 29, 614. ver interpretation of electrocardiograms. Journal of Simonson, E., and Berman, R. (I95I). Differentiation the American Medical Association, 175, 847. between paroxysmal auricular tachycardia with par- Freiermuth, L. J., and Jick, S. (1958). Paroxysmal tial A-V block and auricular flutter. American Heart atrial tachycardia with atrioventricular block. Journal, 42, 387. American Journal of Cardiology, I, 584. Soffer, A. (I961). The changing clinical picture of Friedberg, C. K. (I966). Diseases of the Heart, 3rd ed. digitalis intoxication. Archives of Internal Medicine, W. B. Saunders, Philadelphia and London. 107, 68I.