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Incidence of arrhythmias and ST-segment changes in elderly patients during barium enema studies
Clinical
communications
Incidence of arrhythmias and ST-segment changes elderly patients during barium enema studies William Charles Joel S. Robert Robert
in
R. Roeske, M.D. Higgins, M.D. Karliner, M.D. N. Berk, M.D. A. O’Rourke, M.D.
San Diego, Calif.
There is little information relative to the incidence of potentially serious cardiac arrhythmias and ST-segment alterations that may occur during barium enema x-ray studies. Further, the factors predisposing to such arrhythmias and repolarization abnormalities have not been adequately identified. The purpose of our study was to document the incidence of arrhythmias and significant ST-segment depression in an unselected older population of patients (over age 60), utilizing the continuous electrocardiographic (ECG) monitoring technique. In addition, we sought to examine the effects of glucagon on such ECG abnormalities, since this drug is often given to reduce gastrointestinal spasm and to identify the ECG and physiologic factors that are predictors of ECG abnormalities during the barium enema. Methods
Fifty-eight consecutive patients over the age of 60 (range, 60 to 98) who were having a routine barium enema examination were studied. Patients were prepared with laxatives the night before followed by cleansing enemas on the morning of the x-ray. Immediately before the barium enema a routine 12 lead ECG was performed. In addition, a resting 100 cycle rhythm strip was obtained and the cardiac rhythm was recorded during the Valsalva maneuver and its From the Cardiovascular Department of Radiology,
Division, University
This study wa8 supported Service Graduate Training
in part Grant
Reprint Medical
688
requests: Center,
Department of Medicine, and the of Califotnia, San Diego, Calif. by the United HE-05846-05.
States
Robert A. O’Rourke, M.D., University 225 W. Dickinson St., San Diego, Calif.
Public
Health
of California 92103.
recovery phase. The systemic arterial pressure also was measured in the supine and upright positions with a cuff sphygmomanometer. During the barium study, continuous ECG tape recordings were obtained with a Holter-Avionics Electrocardiorecorder, Model 350 F. An Avionics Millivolt Calibrator, Model 356A, permitted subsequent analysis of ST-segment changes. The patient was selected at random to (1) receive glucagon (1 mg. intravenously preceding the barium study) or (2) enter in a control group by a radiologist who had not seen the ECG data. The barium enema examination was performed in the usual fashion. During each phase of the test the presence or absence of symptoms was recorded. After the barium study, a repeat 12 lead ECG. was obtained. The cardiologist who interpreted the continuous ECG monitor tracings was not aware of the patient’s clinical diagnosis or whether or not glucagon had been given. “Positive” alterations in the continuous ECG were defined as: (1) New atria1 tachyarrhythmias which did not include ectopic atria1 rhythm or wandering atria1 pacemaker. Thus, atria1 arrhythmias considered to be significant were supraventricular tachycardia and atria1 fibrillation. (2) Any form of sinus arrest with an escape rhythm. (3) Premature ventricular contractions (PVC’s) occurring at a frequency of more than 7 per minute and 7 per 100 cycles, multifocal PVC’s within 8 seconds of each other, PVC’s in pairs, or ventricular tachycardia. Episodes of bigeminy, trigeminy, and quadrigeminy that did not satisfy the criteria of 7 PVC’s per minute were not considered to be a positive finding. (4) STsegment depression of greater than 1.0 mV.
December,
1975, Vol. 90, No. 6, pp. 688-694
Arrhythmias
VENTRICULAR TACHYCARDIA
RUN OF TWO PVCs
MULTIFOCAL PVCS
PVCS > 71 YIN AND 71100 CYCLES
and ST-segment
ATRIAL TACHYCARDIA
ESCAPE RHYTHMS
NEW ST OEPRESSION
Fig. 1. The incidence of new arrhythmias and ST-segment depression in 58 patients. described in the figure constituted a “positive” ECG response (see text).
persisting for 80 msec. during the continuous ECG monitor recording. However, if a repolarization abnormality was present on the patient’s resting ECG, or if the patient was receiving digitalis, then 2.0 mV. of additional ST-segment depression was required.‘, ? In addition, a total ectopic activity index, defined as the ratio of nonsinus beats per 100 cycles in the pre-barium enema rhythm strip, was calculated. A second ectopic activity index was derived from the 100 consecutive cycles containing the most frequent ectopic activity recorded during the continuous ECG monitor obtained at the time of the barium enema. A third ectopic activity index relating only to the number of PVC’s per 100 consecutive cycles was computed for both the rhythm strip and the continuous ECG monitor. Results ECG findings. Of the 58 patients studied, 27 had significant alterations in their ECG recordings as defined above. The incidence of new arrhythmias and ST-segment changes in the 58 patients is depicted in Fig. 1. Twenty-three patients had positive studies on the basis of the development of significant arrhythmias during the barium enema (Figs. 2 to 4). Four additional patients were considered to be positive because of new ST-segment changes (Fig. 5). In 16 of the 58 patients (28 per cent), the ECG was considered to be positive based on multiple criteria (Fig, 6). Thirty-one patients had negative studies, including three patients with atria1 arrhythmias that were present before the study and one patient
American
Heart
Journal
changes
POSITIVE BY YULTIPLE CRITERIA
Each
during
barium.
enema
POSITIVE BY ANY CRITERION
of the arrhythmias
who had both pre-existing atria1 fibrillation permanent transvenous pacemaker.
and a
Factors predictive of new arrhythmias.
Age. Table I shows the appearance of significant alterations in the ECG recording as a function of age distribution by decade. In general, more positive tests occurred in the older patients (p < 0.05, x2 analysis); however, the marked variation in each age group suggested the need for more specific predictive factors. Resting ECG. The finding of any ectopic activity on the baseline ECG exhibited a statistically significant association with new ventricular arrhythmias (p < 0.001, x2 analysis, Table II); however, ectopic activity on the resting ECG was not a predictor of new ST-segment depression. Only 7 of 44 patients (16 per c’ent) had ectopic beats on the 12 lead ECG obtained after the barium enema when none was present on the initial record. Conversely, all of the patients with ectopic beats on the initial ECG also demonstrated ectopic activity on the ECG obtained after the barium enema. Seventeen of 18 patients with a ventricular ectopic index of 1 or more determined on 100 cycle rhythm strip recorded prior to the barium enema subsequently exhibited ventricular arrhythmias as contrasted with only four patients who developed ventricular ectopia among 40 patients with a baseline ventricular ectopic index of zero (pt0.001, Table II, Fig. 7). Of 31 pat,ients with a total ectopic activity index of zero prior to the barium enema, only three had a significant ventricular arrhythmia during the barium enema. Thus, as a predictor of a negative ECG during the
689
Roeeke
Fig. 2. ECG recordings from two different patients who developed atria1 arrhythmias during the barium enema are illustrated. Panel A, Paroxysmal atria1 tachycardia. Panel B, Paroxysmal atria1 fibrillation.
Fig. 3. Panel A, Sinus rhythm is interrupted by a PVC, which is followed by a junctional escape rhythm for three beats that is terminated by an ectopic atria1 rhythm. Panel B, Atrioventricular dissociation with a wide QRS complex that may represent either a junctional focus or an accelerated ventricular rhythm.
Fig. 4. Panel A, Multifocal PVC’s occurring within 2 seconds. Panel B, Ventricular the barium enema. The patient was asymptomatic.
690
tachycardia occurring during
December,
1975, Vol. 90, No. 6
Arrhythmias
Fig. 5. enema. barium
and ST-segment changes during barium enema
Panel A, Normal Panel B, Significant enema.
The
ST segments are present during the 100 cycle rhythm strip obtained prior to the barium ST-segment depression associated with a heart rate of 94 beats per minute during the patient had no chest pain during the study.
Fig. 6. Panels A throrcgh D are from the same patient who met including supraventricular and ventricular premature contractions, sinus arrest followed by junctional escape beats.
barium enema, this observation is highly significant (pt0.001, Table II). Fig. 7 depicts the relation of a ventricular ectopic activity index of 1 or more on the rhythm strip before the barium enema to the occurrence of significant ventricular arrhythmias during the barium enema. These data indicate that the presence of even one PVC on a resting 100 cycle rhythm strip has a highly significant predictive
American Heart Journal
multiple criteria for a positive ECG response, multifocal PVC’s. two PVC’s in a row. and
value. Conversely, the lack of any PVC’s on such a rhythm strip correlates with the absence of significant ventricular ectopic activity during the barium enema. Of the 40 patients with a pre-barium enema ventricular ectopic activity index of zero, 21 developed PVC’s but did not meet our criteria for significant ventricular ectopic activity. The other 15 patients exhibited no ventricular ectopic
691
Roeske et al.
I. Age distribution
Table
of patients
ECG findings* “Negative” enema “Positive” enema V only A only ST only V + any
ECG ECG
60-69 70-79 80-89 90-99
during during
barium barium
19
6
5
1
6
8
13
0
2 0 2 2
1 1 2 4
1 1 0
-
other
criterion
II.
Arrhythmias
during barium True positive
ECG findings*
False negative
11
-
ST = new ST“negative” ECG
enema Significance (x2 test)
Baseline ECG V only V+A V+A+ST
with
any
ectopic activity 12/14 9144 13/14 10/44 13/14 14/44
Ectopic activity V only
index
of 1 or more 17/18
PVC/100 4/40
Ectopic activity V only V+A V+A+ST
index
of zero on the 100 cycle 3/31 18/27 3/31 20127 4/31 23/27
p < 0.001 p < 0.001 p < 0.001 cycles p < 0.001 rhythm strip p < 0.001
p<
0.001
p < 0.001
*PVC = premature ventricular contraction; V = ventricular arrhythmia; A = atria1 arrhythmia; ST = new ST-segment depression; p = probability. True positive = ratio of patients with positive ECG findings (see text) on the continuous ECG tape during the barium enema to patients exhibiting ectopic activity on the baseline ECG or rhythm strip. False negative = ratio of patients with positive ECG findings on the continuous ECG tape monitor to patients exhibiting no significant ectopic activity on the baseline ECG or rhythm strip.
activity during the x-ray study. Conversely, among the 21 patients who developed significant ventricular arrhythmias during the barium study, only three satisfied the criteria for significant ventricular ectopic activity on the resting rhythm strip as well. In each case these patients developed multiple positive criteria (atria1 arrhythmias, complex ventricular arrhythmias, ventricular escape beats) during the barium enema. Prior heart disease. Twenty-seven of 58 patients had a history of pre-existing organic cardiac disease. All 27 patients either were receiving cardiac medications (digitalis, diuretics, antiarrhythmic or beta-blocking agents), or had findings of left ventricular enlargement by either ECG or x-ray. Whether such clinically evident
+c
-C +BE
692
-BE
+c +BE
*V = ventricular arrhythmia; A = atria1 arrhythmia; segment depression. For definition of “positive” and findings, see text.
Table
-C
-BE -
IO
Fig. 7. A comparison of the presence (+) or absence (-) of PVC’s on the control 100 cycle rhythm strip (C) with the presence (+ ) or absence (-) of ventricular arrhythmias during the barium enema (BE).
heart disease was present or absent had no predictive value. Thus, 15 of 27 patients with a history of heart disease developed significant ECG abnormalities during the barium enema compared with 12 of 31 patients without a history of cardiac disease (p >0.30). Seventeen of 58 patients were receiving a digitalis preparation at the time of this study. Nine of these 17 patients exhibited positive ECG findings during the barium enema contrasted to 18 of 41 patients who were not receiving digitalis (p>O.70). Effect of glucagon. Thirty randomly chosen patients received 1 mg. of glucagon intravenously to reduce intestinal spasm. Ten of the 30 patients receiving glucagon developed ventricular arrhythmias as compared to 11 of 28 patients who did not receive the drug (p>O.70). The incidence of atria1 arrhythmias and ST-segment changes also did not differ between the two groups. Postural hypotension. Fourteen of 54 patients had a decrease of greater than 30 mm. Hg of systolic arterial pressure upon assuming the erect position, or a systolic blood pressure of less than 90 mm. Hg while standing. Eleven of 14 patients with this finding compared with 15 of 40 patients without this finding developed significant ECG changes during the barium enema when all criteria were considered (pt0.01). December,
1975, Vol. 90, No. 6
Arrhythmias
Additional correlations. Five patients who exhibited escape rhythms during the barium enema all had significant ventricular arrhythmias during the barium enema as well. These five patients were all receiving digitalis. In these five individuals, the Valsalva maneuver performed prior to the barium enema failed to produce an escape rhythm. However, in two of the 58 patients studied, sinus pauses with ventricular or junctional escape beats occurred following the Valsalva maneuver. Both of these patients had no significant arrhythmias or ST-segment depression during the barium enema. Multifocal PVC’s occurring within 8 seconds of each other were observed only in patients who met the general criteria for significant ventricular arrhythmias as well. Five of these patients were not receiving cardiac medications and did not have a prior history of cardiac disease. Discussion
Previous studies have suggested that ECG abnormalities are more frequently encountered during a barium enema x-ray study in patients over the age of 60 and in patients with documented heart disease. Utilizing radioelectrocardiography, Eastwood” reported that 16 of 95 patients in all age groups exhibited potentially dangerous arrhythmias such as frequent or coupled premature ventricular contractions, transient sinus arrest, atrioventricular block, new ST-segment depression, or bundle branch block. However, in his series, 13 of 56 patients over age 60 accounted for 81 per cent of these arrhythmias. The remaining 44 patients showed only minor abnormalities such as premature atria1 contractions and rare unifocal PVC’s. Berman and associates4 studied 62 randomly chosen patients, 33 of whom were over the age of 60. Ten patients exhibited significant ECG changes, including six with STsegment depression and four with arrhythmias. All 10 of these patients were over age 60, and all had a prior history of cardiac disease. Using direct ECG monitoring, Stemple and Montgomery” studied 38 patients (average age 69 years), of whom eight developed premature contractions during all phases of the barium enema; however, they reported no sustained arrhythmias. Nevertheless, they observed ST-segment alterations in half of the patients but did not comment on the magnitude of these changes. Because earlier work indicated that a higher incidence of arrhythmias would be found in older American Heart Journal
and ST-segment changes during barium enema
patients, we confined our study to consecutive patients over the age of 60. The continuous ECG monitoring technique has the advantage over previously employed methods because the arrhythmias are recorded and stored, permitting later analysis of the record. Use of this methodology may explain the higher incidence of dangerous arrhythmias observed in our study compared with previous reports in which direct on-line visualization of the ECG was utilized. With the latter technique, it is possible that the maneuvers employed during the barium enema were influenced by the arrhythmias observed, whereas in our study the radiologist was unaware of the occurrence of serious arrhythmias. Nevertheless, all patients tolerated the x-ray examination well and no cardiac symptoms were noted during the barium study. Thus, it is likely that despite the high incidence of potentially dangerous arrhythmias, catastrophes, such as ventricular fibrillation, sudden death or myocardial infarction, are very unusual events. Our criteria for the definition of serious ventricular arrhythmias were derived from studies in which continuous ECG monitoring was employed in the study of patients after acute myocardial infarction.“, i In 160 such patients, Kotler and associates” reported a sixfold increase in the mortality rate due to sudden death among patients who demonstrated significant ventricular arrhythmias on the continuous tape recording. Because we did not study a homogeneous group of patients, i.e., subjects with proved coronary artery disease, we employed criteria requiring 7 PVC’s per 100 cycles or more, rather than 1 PVC per 500 cycles, in order to score a test positive by the PVC response alone. Otherwise, our other criteria are similar to those previously described by Crawford and associates,; who reported that a combination of 12 hour continuous ECG monitoring, the resting ECG, and a treadmill exercise test yielded a 46 per cent incidence of positive ECG findings in postinfarction patients. In our patients, continuous ECG monitoring during a barium enema (usually a 10 to 45 minute time period) revealed that 47 per cent had positive ECG findings despite the fact that only 8 of our 58 patients (14 per cent) had a previous documented acute myocardial infarction. Whether the patients in our study who had positive ECG findings are at increased risk for sudden death, as noted in previous studies,” * “’ requires further investigation. 693
Roeeke
et al.
The mechanism of arrhythmia production and ST-segment depression may be explained in a variety of ways. The preparation of the patient for the barium enema involves a procedure which often produces dehydration. Thus, many patients showed definite postural blood pressure changes. Our data suggest that such alterations in systemic arterial pressure are an important factor predictive of subsequent arrhythmias and STThese blood pressure segment depression. changes seem to occur independently of ventricular premature beats or other ectopic activity present on the resting tracing. Further, dehydration, fear, and pain during the procedure likely stimulate catecholamine release which increases the heart rate and frequency of ectopic beats. New ST-segment depression (which often correlated with postural blood pressure alterations) usually occurred at heart rates greater than 140 beats/minute, again suggesting catecholamine stimulation. The effect of evacuation of the barium and of distention of the colon had little influence on our results. In this connection, a controlled Valsalva maneuver produced significant ECG changes in only two patients, both of whom had no ECG abnormalities during the barium enema. In the age group studied, a prior history of cardiac disease was not associated with a positive ECG during the barium enema. Nearly half of the patients without a history of heart disease still had positive ECG findings by our criteria. Certainly, it is possible that the barium enema may provide a stress to the patients in this age group with latent cardiac disease that approaches the treadmill test in the production of arrhythmias. Conversely, patients with cardiac disease, under more controlled medical management, may have been in a better state of cardiovascular compensation prior to the barium enema. A 1 mg. intravenous dose of glucagon had no effect on the incidence of arrhythmias or ST-segment changes, suggesting that gastrointestinal spasm plays little or no role in the production of ECG abnormalities. In summary, this study indicates that the physician who requests a barium enema examination should take certain precautions to identify patients at high risk for potentially serious cardiac arrhythmias. The patient over age 60, with a prior cardiac history, pre-existing ectopic
694
beats on a resting ECG, and significant postural changes in systolic systemic arterial pressure, should be considered at risk for such arrhythmias during a barium enema. As an additional measure, a 100 cycle rhythm strip obtained on the morning of the barium enema increases predictive reliability, since the patient with no ectopic beats on the 100 cycle rhythm strip and no postural blood pressure changes is unlikely to develop ECG changes during the barium enema, despite other abnormalities on ECG or a history of cardiac disease. Once the patient at risk has been identified, the physician should consider the possibilities of further cardiac evaluation, antiarrhythmic drug therapy, and ECG monitoring during the barium enema. In addition, the radiologist should be alerted to the possible occurrence of arrhythmias and repolarization abnormalities during the procedure. We wish to thank Ms. Lynn their technical assistance.
Gorum
and Mr.
Dan
Haas
for
REFERENCES 1.
2.
3. 4.
5.
6.
7.
8.
9.
10.
Cohn, P. F., Vokonas, P. S., Herman, M. V., and Gorlin, R.: Postexercise electrocardiograms, Circulation 43:648, 1971. Bartel, A. G., Behar, V. S., Peter, R. H., Orgain, E. S., and Kong, Y.: Graded exercise stress tests. in angiographically documented coronary artery disease, Circulation 49:348, 1974. Eastwood, G. L.: ECG abnormalities associated with the barium enema, J. A. M. A. 219:719, 1972. Berman, C. Z., Jacobs, M. G., and Bernstein, A.: Hazards of the barium enema examination as studied by electrocardiographic telemetry: A preliminary report, J. Am. Geriatr. Sot. 13:672, 1965. Stemple, J., and Montgomery, C.: Nonspecific electrocardiographic abnormalities: The EKG during the barium enema procedure, Marquette Mad. Rev. 27:20, 1961. Kotler, M. N., Tabatznik, B., Mower, M. M., and Tominaga, S.: Prognostic significance of ventricular ectopic beats with respect to sudden death in the late postinfarction period, Circulation 47:959, 1973. Crawford, M., O’Rourke, R. A., Ramakrishna, N., Henning, H., and Ross, J.: Comparative effectiveness of exercise testing and continuous monitoring for detecting arrhythmias in patients with previous myocardial infarction, Circulation 50:301, 1974. Chiang, B. N., Perlman, L. V., Ostrander, L. D., Jr., and Epstein, F. H.: Relationship of premature systoles to coronary heart disease and sudden death in the Tecumseh epidemiologic study, Ann. Intern. Med. 70:1159, 1969. Prognostic importance of premature beats following myocardial infarction. Experience in the coronary drug project, J. A. M. A. 223:1116, 1973. Moss, A. J., DeCamille, J., Engstrom, F., Hoffman, W., Odoroff, C., and Davis, H.: The posthosfiital phase of myocardial infarction. Identification of patients with increased mortality risk, Circulation 49:460, 1974.
December,
1975, Vol. 90, No. ‘j
communications
Incidence of arrhythmias and ST-segment changes elderly patients during barium enema studies William Charles Joel S. Robert Robert
in
R. Roeske, M.D. Higgins, M.D. Karliner, M.D. N. Berk, M.D. A. O’Rourke, M.D.
San Diego, Calif.
There is little information relative to the incidence of potentially serious cardiac arrhythmias and ST-segment alterations that may occur during barium enema x-ray studies. Further, the factors predisposing to such arrhythmias and repolarization abnormalities have not been adequately identified. The purpose of our study was to document the incidence of arrhythmias and significant ST-segment depression in an unselected older population of patients (over age 60), utilizing the continuous electrocardiographic (ECG) monitoring technique. In addition, we sought to examine the effects of glucagon on such ECG abnormalities, since this drug is often given to reduce gastrointestinal spasm and to identify the ECG and physiologic factors that are predictors of ECG abnormalities during the barium enema. Methods
Fifty-eight consecutive patients over the age of 60 (range, 60 to 98) who were having a routine barium enema examination were studied. Patients were prepared with laxatives the night before followed by cleansing enemas on the morning of the x-ray. Immediately before the barium enema a routine 12 lead ECG was performed. In addition, a resting 100 cycle rhythm strip was obtained and the cardiac rhythm was recorded during the Valsalva maneuver and its From the Cardiovascular Department of Radiology,
Division, University
This study wa8 supported Service Graduate Training
in part Grant
Reprint Medical
688
requests: Center,
Department of Medicine, and the of Califotnia, San Diego, Calif. by the United HE-05846-05.
States
Robert A. O’Rourke, M.D., University 225 W. Dickinson St., San Diego, Calif.
Public
Health
of California 92103.
recovery phase. The systemic arterial pressure also was measured in the supine and upright positions with a cuff sphygmomanometer. During the barium study, continuous ECG tape recordings were obtained with a Holter-Avionics Electrocardiorecorder, Model 350 F. An Avionics Millivolt Calibrator, Model 356A, permitted subsequent analysis of ST-segment changes. The patient was selected at random to (1) receive glucagon (1 mg. intravenously preceding the barium study) or (2) enter in a control group by a radiologist who had not seen the ECG data. The barium enema examination was performed in the usual fashion. During each phase of the test the presence or absence of symptoms was recorded. After the barium study, a repeat 12 lead ECG. was obtained. The cardiologist who interpreted the continuous ECG monitor tracings was not aware of the patient’s clinical diagnosis or whether or not glucagon had been given. “Positive” alterations in the continuous ECG were defined as: (1) New atria1 tachyarrhythmias which did not include ectopic atria1 rhythm or wandering atria1 pacemaker. Thus, atria1 arrhythmias considered to be significant were supraventricular tachycardia and atria1 fibrillation. (2) Any form of sinus arrest with an escape rhythm. (3) Premature ventricular contractions (PVC’s) occurring at a frequency of more than 7 per minute and 7 per 100 cycles, multifocal PVC’s within 8 seconds of each other, PVC’s in pairs, or ventricular tachycardia. Episodes of bigeminy, trigeminy, and quadrigeminy that did not satisfy the criteria of 7 PVC’s per minute were not considered to be a positive finding. (4) STsegment depression of greater than 1.0 mV.
December,
1975, Vol. 90, No. 6, pp. 688-694
Arrhythmias
VENTRICULAR TACHYCARDIA
RUN OF TWO PVCs
MULTIFOCAL PVCS
PVCS > 71 YIN AND 71100 CYCLES
and ST-segment
ATRIAL TACHYCARDIA
ESCAPE RHYTHMS
NEW ST OEPRESSION
Fig. 1. The incidence of new arrhythmias and ST-segment depression in 58 patients. described in the figure constituted a “positive” ECG response (see text).
persisting for 80 msec. during the continuous ECG monitor recording. However, if a repolarization abnormality was present on the patient’s resting ECG, or if the patient was receiving digitalis, then 2.0 mV. of additional ST-segment depression was required.‘, ? In addition, a total ectopic activity index, defined as the ratio of nonsinus beats per 100 cycles in the pre-barium enema rhythm strip, was calculated. A second ectopic activity index was derived from the 100 consecutive cycles containing the most frequent ectopic activity recorded during the continuous ECG monitor obtained at the time of the barium enema. A third ectopic activity index relating only to the number of PVC’s per 100 consecutive cycles was computed for both the rhythm strip and the continuous ECG monitor. Results ECG findings. Of the 58 patients studied, 27 had significant alterations in their ECG recordings as defined above. The incidence of new arrhythmias and ST-segment changes in the 58 patients is depicted in Fig. 1. Twenty-three patients had positive studies on the basis of the development of significant arrhythmias during the barium enema (Figs. 2 to 4). Four additional patients were considered to be positive because of new ST-segment changes (Fig. 5). In 16 of the 58 patients (28 per cent), the ECG was considered to be positive based on multiple criteria (Fig, 6). Thirty-one patients had negative studies, including three patients with atria1 arrhythmias that were present before the study and one patient
American
Heart
Journal
changes
POSITIVE BY YULTIPLE CRITERIA
Each
during
barium.
enema
POSITIVE BY ANY CRITERION
of the arrhythmias
who had both pre-existing atria1 fibrillation permanent transvenous pacemaker.
and a
Factors predictive of new arrhythmias.
Age. Table I shows the appearance of significant alterations in the ECG recording as a function of age distribution by decade. In general, more positive tests occurred in the older patients (p < 0.05, x2 analysis); however, the marked variation in each age group suggested the need for more specific predictive factors. Resting ECG. The finding of any ectopic activity on the baseline ECG exhibited a statistically significant association with new ventricular arrhythmias (p < 0.001, x2 analysis, Table II); however, ectopic activity on the resting ECG was not a predictor of new ST-segment depression. Only 7 of 44 patients (16 per c’ent) had ectopic beats on the 12 lead ECG obtained after the barium enema when none was present on the initial record. Conversely, all of the patients with ectopic beats on the initial ECG also demonstrated ectopic activity on the ECG obtained after the barium enema. Seventeen of 18 patients with a ventricular ectopic index of 1 or more determined on 100 cycle rhythm strip recorded prior to the barium enema subsequently exhibited ventricular arrhythmias as contrasted with only four patients who developed ventricular ectopia among 40 patients with a baseline ventricular ectopic index of zero (pt0.001, Table II, Fig. 7). Of 31 pat,ients with a total ectopic activity index of zero prior to the barium enema, only three had a significant ventricular arrhythmia during the barium enema. Thus, as a predictor of a negative ECG during the
689
Roeeke
Fig. 2. ECG recordings from two different patients who developed atria1 arrhythmias during the barium enema are illustrated. Panel A, Paroxysmal atria1 tachycardia. Panel B, Paroxysmal atria1 fibrillation.
Fig. 3. Panel A, Sinus rhythm is interrupted by a PVC, which is followed by a junctional escape rhythm for three beats that is terminated by an ectopic atria1 rhythm. Panel B, Atrioventricular dissociation with a wide QRS complex that may represent either a junctional focus or an accelerated ventricular rhythm.
Fig. 4. Panel A, Multifocal PVC’s occurring within 2 seconds. Panel B, Ventricular the barium enema. The patient was asymptomatic.
690
tachycardia occurring during
December,
1975, Vol. 90, No. 6
Arrhythmias
Fig. 5. enema. barium
and ST-segment changes during barium enema
Panel A, Normal Panel B, Significant enema.
The
ST segments are present during the 100 cycle rhythm strip obtained prior to the barium ST-segment depression associated with a heart rate of 94 beats per minute during the patient had no chest pain during the study.
Fig. 6. Panels A throrcgh D are from the same patient who met including supraventricular and ventricular premature contractions, sinus arrest followed by junctional escape beats.
barium enema, this observation is highly significant (pt0.001, Table II). Fig. 7 depicts the relation of a ventricular ectopic activity index of 1 or more on the rhythm strip before the barium enema to the occurrence of significant ventricular arrhythmias during the barium enema. These data indicate that the presence of even one PVC on a resting 100 cycle rhythm strip has a highly significant predictive
American Heart Journal
multiple criteria for a positive ECG response, multifocal PVC’s. two PVC’s in a row. and
value. Conversely, the lack of any PVC’s on such a rhythm strip correlates with the absence of significant ventricular ectopic activity during the barium enema. Of the 40 patients with a pre-barium enema ventricular ectopic activity index of zero, 21 developed PVC’s but did not meet our criteria for significant ventricular ectopic activity. The other 15 patients exhibited no ventricular ectopic
691
Roeske et al.
I. Age distribution
Table
of patients
ECG findings* “Negative” enema “Positive” enema V only A only ST only V + any
ECG ECG
60-69 70-79 80-89 90-99
during during
barium barium
19
6
5
1
6
8
13
0
2 0 2 2
1 1 2 4
1 1 0
-
other
criterion
II.
Arrhythmias
during barium True positive
ECG findings*
False negative
11
-
ST = new ST“negative” ECG
enema Significance (x2 test)
Baseline ECG V only V+A V+A+ST
with
any
ectopic activity 12/14 9144 13/14 10/44 13/14 14/44
Ectopic activity V only
index
of 1 or more 17/18
PVC/100 4/40
Ectopic activity V only V+A V+A+ST
index
of zero on the 100 cycle 3/31 18/27 3/31 20127 4/31 23/27
p < 0.001 p < 0.001 p < 0.001 cycles p < 0.001 rhythm strip p < 0.001
p<
0.001
p < 0.001
*PVC = premature ventricular contraction; V = ventricular arrhythmia; A = atria1 arrhythmia; ST = new ST-segment depression; p = probability. True positive = ratio of patients with positive ECG findings (see text) on the continuous ECG tape during the barium enema to patients exhibiting ectopic activity on the baseline ECG or rhythm strip. False negative = ratio of patients with positive ECG findings on the continuous ECG tape monitor to patients exhibiting no significant ectopic activity on the baseline ECG or rhythm strip.
activity during the x-ray study. Conversely, among the 21 patients who developed significant ventricular arrhythmias during the barium study, only three satisfied the criteria for significant ventricular ectopic activity on the resting rhythm strip as well. In each case these patients developed multiple positive criteria (atria1 arrhythmias, complex ventricular arrhythmias, ventricular escape beats) during the barium enema. Prior heart disease. Twenty-seven of 58 patients had a history of pre-existing organic cardiac disease. All 27 patients either were receiving cardiac medications (digitalis, diuretics, antiarrhythmic or beta-blocking agents), or had findings of left ventricular enlargement by either ECG or x-ray. Whether such clinically evident
+c
-C +BE
692
-BE
+c +BE
*V = ventricular arrhythmia; A = atria1 arrhythmia; segment depression. For definition of “positive” and findings, see text.
Table
-C
-BE -
IO
Fig. 7. A comparison of the presence (+) or absence (-) of PVC’s on the control 100 cycle rhythm strip (C) with the presence (+ ) or absence (-) of ventricular arrhythmias during the barium enema (BE).
heart disease was present or absent had no predictive value. Thus, 15 of 27 patients with a history of heart disease developed significant ECG abnormalities during the barium enema compared with 12 of 31 patients without a history of cardiac disease (p >0.30). Seventeen of 58 patients were receiving a digitalis preparation at the time of this study. Nine of these 17 patients exhibited positive ECG findings during the barium enema contrasted to 18 of 41 patients who were not receiving digitalis (p>O.70). Effect of glucagon. Thirty randomly chosen patients received 1 mg. of glucagon intravenously to reduce intestinal spasm. Ten of the 30 patients receiving glucagon developed ventricular arrhythmias as compared to 11 of 28 patients who did not receive the drug (p>O.70). The incidence of atria1 arrhythmias and ST-segment changes also did not differ between the two groups. Postural hypotension. Fourteen of 54 patients had a decrease of greater than 30 mm. Hg of systolic arterial pressure upon assuming the erect position, or a systolic blood pressure of less than 90 mm. Hg while standing. Eleven of 14 patients with this finding compared with 15 of 40 patients without this finding developed significant ECG changes during the barium enema when all criteria were considered (pt0.01). December,
1975, Vol. 90, No. 6
Arrhythmias
Additional correlations. Five patients who exhibited escape rhythms during the barium enema all had significant ventricular arrhythmias during the barium enema as well. These five patients were all receiving digitalis. In these five individuals, the Valsalva maneuver performed prior to the barium enema failed to produce an escape rhythm. However, in two of the 58 patients studied, sinus pauses with ventricular or junctional escape beats occurred following the Valsalva maneuver. Both of these patients had no significant arrhythmias or ST-segment depression during the barium enema. Multifocal PVC’s occurring within 8 seconds of each other were observed only in patients who met the general criteria for significant ventricular arrhythmias as well. Five of these patients were not receiving cardiac medications and did not have a prior history of cardiac disease. Discussion
Previous studies have suggested that ECG abnormalities are more frequently encountered during a barium enema x-ray study in patients over the age of 60 and in patients with documented heart disease. Utilizing radioelectrocardiography, Eastwood” reported that 16 of 95 patients in all age groups exhibited potentially dangerous arrhythmias such as frequent or coupled premature ventricular contractions, transient sinus arrest, atrioventricular block, new ST-segment depression, or bundle branch block. However, in his series, 13 of 56 patients over age 60 accounted for 81 per cent of these arrhythmias. The remaining 44 patients showed only minor abnormalities such as premature atria1 contractions and rare unifocal PVC’s. Berman and associates4 studied 62 randomly chosen patients, 33 of whom were over the age of 60. Ten patients exhibited significant ECG changes, including six with STsegment depression and four with arrhythmias. All 10 of these patients were over age 60, and all had a prior history of cardiac disease. Using direct ECG monitoring, Stemple and Montgomery” studied 38 patients (average age 69 years), of whom eight developed premature contractions during all phases of the barium enema; however, they reported no sustained arrhythmias. Nevertheless, they observed ST-segment alterations in half of the patients but did not comment on the magnitude of these changes. Because earlier work indicated that a higher incidence of arrhythmias would be found in older American Heart Journal
and ST-segment changes during barium enema
patients, we confined our study to consecutive patients over the age of 60. The continuous ECG monitoring technique has the advantage over previously employed methods because the arrhythmias are recorded and stored, permitting later analysis of the record. Use of this methodology may explain the higher incidence of dangerous arrhythmias observed in our study compared with previous reports in which direct on-line visualization of the ECG was utilized. With the latter technique, it is possible that the maneuvers employed during the barium enema were influenced by the arrhythmias observed, whereas in our study the radiologist was unaware of the occurrence of serious arrhythmias. Nevertheless, all patients tolerated the x-ray examination well and no cardiac symptoms were noted during the barium study. Thus, it is likely that despite the high incidence of potentially dangerous arrhythmias, catastrophes, such as ventricular fibrillation, sudden death or myocardial infarction, are very unusual events. Our criteria for the definition of serious ventricular arrhythmias were derived from studies in which continuous ECG monitoring was employed in the study of patients after acute myocardial infarction.“, i In 160 such patients, Kotler and associates” reported a sixfold increase in the mortality rate due to sudden death among patients who demonstrated significant ventricular arrhythmias on the continuous tape recording. Because we did not study a homogeneous group of patients, i.e., subjects with proved coronary artery disease, we employed criteria requiring 7 PVC’s per 100 cycles or more, rather than 1 PVC per 500 cycles, in order to score a test positive by the PVC response alone. Otherwise, our other criteria are similar to those previously described by Crawford and associates,; who reported that a combination of 12 hour continuous ECG monitoring, the resting ECG, and a treadmill exercise test yielded a 46 per cent incidence of positive ECG findings in postinfarction patients. In our patients, continuous ECG monitoring during a barium enema (usually a 10 to 45 minute time period) revealed that 47 per cent had positive ECG findings despite the fact that only 8 of our 58 patients (14 per cent) had a previous documented acute myocardial infarction. Whether the patients in our study who had positive ECG findings are at increased risk for sudden death, as noted in previous studies,” * “’ requires further investigation. 693
Roeeke
et al.
The mechanism of arrhythmia production and ST-segment depression may be explained in a variety of ways. The preparation of the patient for the barium enema involves a procedure which often produces dehydration. Thus, many patients showed definite postural blood pressure changes. Our data suggest that such alterations in systemic arterial pressure are an important factor predictive of subsequent arrhythmias and STThese blood pressure segment depression. changes seem to occur independently of ventricular premature beats or other ectopic activity present on the resting tracing. Further, dehydration, fear, and pain during the procedure likely stimulate catecholamine release which increases the heart rate and frequency of ectopic beats. New ST-segment depression (which often correlated with postural blood pressure alterations) usually occurred at heart rates greater than 140 beats/minute, again suggesting catecholamine stimulation. The effect of evacuation of the barium and of distention of the colon had little influence on our results. In this connection, a controlled Valsalva maneuver produced significant ECG changes in only two patients, both of whom had no ECG abnormalities during the barium enema. In the age group studied, a prior history of cardiac disease was not associated with a positive ECG during the barium enema. Nearly half of the patients without a history of heart disease still had positive ECG findings by our criteria. Certainly, it is possible that the barium enema may provide a stress to the patients in this age group with latent cardiac disease that approaches the treadmill test in the production of arrhythmias. Conversely, patients with cardiac disease, under more controlled medical management, may have been in a better state of cardiovascular compensation prior to the barium enema. A 1 mg. intravenous dose of glucagon had no effect on the incidence of arrhythmias or ST-segment changes, suggesting that gastrointestinal spasm plays little or no role in the production of ECG abnormalities. In summary, this study indicates that the physician who requests a barium enema examination should take certain precautions to identify patients at high risk for potentially serious cardiac arrhythmias. The patient over age 60, with a prior cardiac history, pre-existing ectopic
694
beats on a resting ECG, and significant postural changes in systolic systemic arterial pressure, should be considered at risk for such arrhythmias during a barium enema. As an additional measure, a 100 cycle rhythm strip obtained on the morning of the barium enema increases predictive reliability, since the patient with no ectopic beats on the 100 cycle rhythm strip and no postural blood pressure changes is unlikely to develop ECG changes during the barium enema, despite other abnormalities on ECG or a history of cardiac disease. Once the patient at risk has been identified, the physician should consider the possibilities of further cardiac evaluation, antiarrhythmic drug therapy, and ECG monitoring during the barium enema. In addition, the radiologist should be alerted to the possible occurrence of arrhythmias and repolarization abnormalities during the procedure. We wish to thank Ms. Lynn their technical assistance.
Gorum
and Mr.
Dan
Haas
for
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1975, Vol. 90, No. ‘j