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Electrovectorcardiographic changes after proximal right coronary artery venous bypass graft and distal gas endarterectomy
Ektrovectorcardiographic Changes After Proximal Right Coronary Artery Venous Bypass Graft and Distal Gas Endatterectomy
ALBERT0
BENCHIMOL,
MD,
FACC
STEVEN D. PROMISLOFF. MD KENNETH B. DESSER, MD
Phoenix. Arizona
Serial electrocardiograms and vectorcardiograms were obtained from 10 consecutive patients who underwent combined proximal right aortocoronary saphenous vein bypass graft implantation and distal right coronary gas endarterectomy. Nine of these subjects manifested postoperative eiectrovectorcardiographic changes of acute inferior wail myocardiai infarction. Only 1 of 13 other patients who were subjected to right bypass graft implantation without gas endarterectomy had similar findings. Ail 9 patients who were subjected to gas endarterectomy and who manifested postoperative patterns of infarction had a clinically uncomplicated postoperative course and were discharged on the 10th to 12th postoperative day. it is concluded that postoperative eiectrovectorcardiographic evidence of acute inferior wail infarction is prevalent in patients subjected to combined proximal right aortocoronary bypass graft implantation and distal right coronary gas endarterectomy. These changes may be based on physical consequences of the gas endarterectomy.
Surgical approaches currently utilized for the direct treatment of right coronary artery disease include aortocoronary saphenous vein bypass, l total coronary artery gas endarterectomy2m4 and a combina5*s No specific electrocardiographic changes tion of these techniques. have been noted after these procedures. Reconstruction of the occluded left anterior descending artery by means of proximal vein bypass grafting and distal gas endarterectomy has recently been described.7 This latter operation has also been applied to the occluded a higher early postoperative paright coronary artery, s-9 providing tency rate than the 70 percent figure cited for total gas endarterectomy. g This paper describes postoperative electrovectorcardiographic changes associated with the combined proximal right coronary artery bypass and distal gas endarterectomy procedure. Nine of 10 subjects so treated manifested postoperative cardiographic signs of recent inferior wall myocardial infarction. From the Institute for Cardiovascular Diseases, Good Samaritan Hospital, Phoenix, Ark. This study was supported in part by the Nichols’ Memorial Fund. Manuscript received January 20, 1972; revised manuscript received March 21, 1972; accepted April 18, 1972.
Address for reprints: Albert0 Benchimol, MD, Good Samaritan Hospital, 1033 East McDowell Rd., Phoenix, Ark. 85006.
466
October 1972
Material
and Methods
Group I consisted of 10 consecutive patients with symptomatic coronary artery disease who underwent combined distal right coronary gas endarterectomy and proximal right aortocoronary artery saphenous vein bypass graft procedures between March 16 and August 19, 1971. In addition, 5 of these patients also had left circumflex or anterior descending artery aortocoronary graft implants. One patient died at operation and was excluded from the study. The patients were all male; their ages ranged from 49 to 62 years (mean 55 years).
The American Journal of CARDIOLOGY
Volume 30
ELECTROCARDIOGRAM
AFTER DISTAL
Group II consisted of !13 consecutive patients who had operative procedures exclusive of coronary gas endarterectomy for symptomatic coronary artery disease. These patients underwent right aortocoronary artery saphenous vein bypass, alone or in combination with aortocoronary saphenous vein bypass to the left anterior descending or left circumflex arteries, between February 19, 1970 and May 6, 1971. The degree and extent of coronary artery disease in this group of patients was similar to that of subjects in Group I. One patient died at operation and was excluded from the study. All patients in group II were male; their ages ranged from 37 to 58 years (mean 48 years). All preoperative diagnoses were based on complete left and right heart catheterization, selective coronary cineangiographic studies, left ventriculograms, indicator-dilution curves and hemodynamic indexes that define ventricular function. The operations were performed under halothane-morphine anesthesia with cardiopulmonary bypass. The technique utilized at our institution for combined distal gas endarterectomy and proximal aortocoronary saphenous vein bypass is similar to that described by Urschel et al.9 Electrocardiogralits were recorded with a Burdick model EK-4 direct-writing electrocardiograph at paper speeds of 25 mm/set. Vectorcardiograms in the 3 plane projections were recorded in the supine position using the Frank lead system.lO The fourth intercostal space was used for placement of the chest electrodes as suggested by Langner et al.rl for the supine position. The vectorcardiograms were recorded with a DR-8 Electronics for Medicine light-beam oscilloscopic photographic recorder using a vectorcardiographic channel (model VET-6). Still and timed vectorcardiograms (running loops) were taken in the frontal, left sagittal and horizontal planes according to previously described techniques.12Js Electrocardiograms were obtained in all patients on the day before and on several successive days after the operation. Vectorcardiograms were obtained preoperatively
PRE-OP.
1 e -1O
/ -co
P
of Postoperative
Electrovectorcardiographic
Group
I
Group I I
IlO.
IlO.
%
%
Inferior wall MI, acute Inferior wall MI, possible reinfarction Inferior wall MI, total
6*
60
1
8
3
30
0
0
9
90
1
8
No changes or ST-T segment changes only
1
10
12
92
*One patient also had acute infarction. Ml = myocardial infarction.
anteroseptal
wall myocardial
from all but 1 patient, who was studied at another hospital. Postoperative vectorcardiograms were available for review in all but 3 patients in group II. These tracings were obtained on the second or third postoperative day in the majority of patients. In no instance were the postoperative vectorcardiograms recorded more than 60 days after the operation, and in no case did the electrocardiographic QRS patterns recorded simultaneously with the postoperative vectorcardiograms differ substantially from those of electrocardiograms taken during the immediate postoperative period. Serial postoperative serum enzyme levels (glutamic oxaloacetic transaminase [SGOT], glutamic pyruvic transaminase [SGPT], lactic dehydrogenase [LDH], creatine
4
. ‘2%
Comparison Changes
+ 20 f
ET AL.
I
POST-OR
‘O.:.:‘”
‘\
TABLE
GAS ENDARTERECTOMY-BENCHIMOL
7/20/71
P LOOP fl ml”.
4
CORONARY
’
;0-
:+--G-+
-
-P
7/30(71 Y-
LOOP
-
I
10A
,,30
\ .
Id
, *,- -::
FP
FIGURE l.Vectorcardiog~rams and electrocardiograms obtained from a 50 year old man who underwent combined proximal right aortocoronary bypass graft implantation, distal right coronary gas endarterectomy and left.anterior descending aortocoronary bypass. FP = frontal plane; HP =: horizontal plane; SP = sagittal plane. The preoperative records (left) show evidence of an old anteroseptal myocardial infarction. Postoperative records (right) demonstrate a recent inferior wall myocardial infarction. Note the change in rotation of the frontal and sagittal plane vectorcardiographic QRS loops from counterclockwise to clockwise. There are prominent superiorly directed QRS vectors, and deep Q waves in leads II, III and aVF of the electrocardiogram, all indicative of a recent inferior wall infarction.
October 1972
The American Journal of CARDIOLOGY
Volume 30
467
ELECTROCARDIOGRAM
AFTER DISTAL
PRE-OP.
CORONARY
GAS ENDARTERECTOMY-BENCHIMOL
8/8/71
POST.
ET AL.
OP.
8/11/71
FIGURE 2. Vectorcardiograms and electrocardiogram8 recorded from a 53 year old man who underwent proximal right aortocoronary bypass graft implantation and distal right coronary gas endarterectomy. The preoperative records (left) show nonspecific S-T segment and T wave changes. Postoperative records (right) reveal changes compatible’ with a recent inferior wall myocardial infarction. Note the postoperative Q waves in leads II, III and aVF. In the postoperative vectorcardiogram there are prominent superiorly directed QRS vectors in the frontal and left sagittal planes. Also note the change in rotation of the frontal and sagittal QRS loops from “figure-ofeight” (preoperative) to clockwise (postoperative). PRE-OP.
E/l0
POST-OP.
/71 P LOOP
e/13/71
P LOOP w
% In”.
u
Y
ml”.
phosphokinase [CPK]) were available for review in 7 patients in group I.
c_ p_ > 10 0
FP
FP
Results
\
c
’
HP
,’
I
’
/
,*’ lmv.
50
QRS ’
’
1 mv. II
I
Ill
-aVR
-J-r-Vl
8YL
aVF
v3
V6
-.--
V3
V6
Vl
FIGURE 3. Vectorcardiograms and electrocardiograms recorded from a 60 year old man who underwent combined proximal right aortocoronary bypass graft implantation and distal right coronary gas endarterectomy. The preoperative records (left) show nonspecific S-T segment and T wave changes. Postoperative records (right) reveal changes compatible with an acute inferior wall myocardial infarction. Note the postoperative appearance of prominent superiorly oriented initial QRS vector forces in the frontal and left sagittal loops of the vectorcardiogram, and the development of Q waves in leads I I, II I and aVF of the electrocardiogram.
468
October 1972
The American
Journal of CARDIOLOGY
A summary of the postoperative electrocardiographic and vectorcardiographic changes in both groups is presented in Table I. Group I: Of the 10 patients in this group who underwent combined distal right coronary gas endarterectomy and proximal right aortocoronary saphenous vein bypass procedures, 6 had preoperative electrocardiograms that did not demonstrate inferior wall myocardial infarction. However, in the early postoperative period, all 6 patients manifested electrocardiographic evidence of an acute inferior wall infarction (Fig. 1 to 3). Three of the remaining 4 patients, with preoperative electrocardiographic evidence of old inferior wall myocardial infarction, manifested postoperative changes compatible with reinfarction of the inferior wall. We considered this latter diagnosis to be present on the electrocardiogram when a preoperative qR pattern in 2 of the 3 inferior leads (II, III, aVF) changed to QS and was associated with appropriate abnormalities of the T waves and S-T segments, including a “current of injury” pattern (Fig. 4). On the vectorcardiogram a pattern of reinfarction was considered to be present when there was significant superior displacement of initial 25 msec QRS forces in the frontal and left sagittal planes compared with the preoperative records (Fig. 5). One patient, with normal preoperative electrocardiograms, manifested no QRS changes postoperatively. Group II: The 13 patients in this group all underwent right aortocoronary bypass graft implantation. In addition, 6 subjects had left aortocoronary bypass grafts and 1 underwent a Vineberg internal mammary artery procedure. Postoperatively, only 1 patient showed electrocardiographic changes consistent with acute inferior wall myocardial infarction
Volume 30
ELECTROCARDIOGRAM
AFTER DISTAL
CORONARY
GAS ENDARTERECTOMY-BENCHIMOL
PRE-OP 3124171
PRE-OP 8/16/71
POST-QP
POS T-OP 3/26/71
ET AL.
417171
8/18/71
FIGURE 4. Electrocardiograms recorded from a 56 year old man who underwent combined proximal right aortocoronary saphenous vein bypass graft implantation, distal right coronary gas endarterectomy, and aortocoronary saphenous vein bypass graft to the left circumflex coronary artery. The preoperative tracing (upper panel) is consistent with an old inferior wall myocardial infarction. There are Q waves present in leads II, I II, and aVF. The postoperative record (lower panel) shows evidence of reinfarction of the inferior wail myocardium. Note the OS pattern now present in lead I I I, the deepened Q wave in aVF, and the significant loss of R wave voltage in all 3 inferior leads.
PRE.OP.
FIGURE 6. Electrocardiograms recorded from a 46 year old man who underwent right and left anterior descending aortocoronary saphenous vein bypass graft implantation. The preoperative tracing (left) shows left axis deviation of minor degree. The postoperative records (middle and right) show evolution of an acute inferior wall myocardial infarction, with development of deep Q waves and loss of initial R wave voltage in leads II, III and aVF.
POST -09
2/9/?1
20
i-
l/L9/71 4
‘.
P LOOP
)
!4 mr.
‘t-0
aVF
FIGURE 5. Electrocardiograms and vectorcardiograms recorded from a 56 year old man who underwent combined proximal right aortocoronary saphenous vein bypass graft implantation, distal right coronary gas endarterectomy and aortocoronary saphenous vein bypass to the left anterior descending coronary artery. The preoperative tracings (left) are consistent with an old inferior wall myocardial infarction. The postoperative records (right) show changes of reinfarction of the inferior wall. Note the total loss of R wave voltage and development of a QS pattern in leads II and aVF of the postoperative electrocardiogram. Note also that postoperatively there is further superior displacement of the initial vectorcardiographic forces in the frontal and left sagittal planes (initial vectors oriented superiorly for 34 msec preoperatively, for 56 msec postoperatively). The rotation of the left sagittal QRS loop changes from counterclockwise to clockwise.
(Fig. 6). No other patient in this group had significant QRS changes indicative of acute infarction or reinfarction. However, 1 patient did manifest postoperative electrocardiographic changes compatible with transient left posterior hemiblock and right bundle branch blockl” (Fig. 7). Clinical course: ‘The 9 patients in group I who exhibited postoperative electrocardiographic changes
compatible with a recent inferior wall infarction had a relatively uncomplicated postoperative course; none had chest pain suggestive of angina pectoris or acute myocardial infarction. All 9 patients were discharged from the hospital 10 to 12 days after the operation. The remaining patient manifested isolated S-T segment and T wave changes after the operation. On
October 1972
The American
Journal of CARDIOLOGY
Volume 30
469
ELECTROCARDIOGRAM
PRE-OP
AFTER DISTAL
CORONARY
GAS ENDARTERECTOMY-BENCHIMOL
POST-OP 12/4/70
12/6/70
ET AL.
onary arteries 2 to 3 months after operation. Of these, 4 had patent right aortocoronary grafts. In 4 of 5 patients, prior 80 to 90 percent obstructive lesions in the right coronary artery progressed to complete occlusion. Discussion
FIGURE 7. Electrocardiograms from a 55 year old man who underwent right aortocoronary saphenous vein bypass graft implantation. A preoperative electrocardiogram (12/l /70) shows nonspecific ST-T changes and a ventricular extrasystole. On the first postoperative day (12/4/70) there are atrial premature beats, right axis deviation, a prominent R wave in lead aVR, rsR’ in lead VI and broad S waves in lead Vg, all suggestive of combined left posterior hemiblock and right bundle branch block. On 12/6/70 the QRS complexes do not significantly differ from those recorded on 12 /I 170.
the third postoperative day he experienced chest pain identical with his preoperative angina1 pain and different from his chest wall incisional pain. His symptoms progressed, and on the 12th postoperative day he was subjected to bypass graft angiographic studies which revealed total occlusion of the right bypass graft at its origin. Enzyme data: Serum GOT, GPT, LDH and CPK values were available for review in 7 patients in group I for at least 2 consecutive postoperative days. All but 1 of these patients manifested a postoperative pattern of inferior wall myocardial infarction. The serum LDH and CPK values were significantly increased in 6 patients. One subject had normal LDH and only minimally increased CPK. SGOT was transiently increased in 5 patients, including a single subject who did not have an infarction pattern on the electrocardiogram. Only 2 subjects had isolated SGOT levels above 100 units. SGPT remained normal in all patients. Follow-up: Five of the 9 patients in group I with a pattern of inferior wall myocardial infarction returned for angiographic study of their grafts and cor-
479
October 1972
The American
Journal of CARDIOLOGY
Electrocardiographic abnormalities resembling those of myocardial infarction, including abnormal Q waves, have been reported in association with open heart surgery.ls Such abnormalities are attributed to cross-clamping of the aorta, institution of cardiopulmonary bypass, perfusion of the coronary arteries with cooled blood, and localized abnormalities of electrolytes and membrane potentials.ls Supporting the thesis that these electrocardiographic alterations are not due to myocardial necrosis is their transient nature and immediate reversal when cardiopulmonary bypass is discontinued. Electrovectorcardiographic findings of inferior wall infarction described here were noted 12 to 24 hours after right coronary gas endarterectomy and generally followed an evolutionary course. Furthermore, the changes persisted for 2 to 3 months postoperatively in those patients who had follow-up electrocardiograms. Although several studies have dealt with coronary gas endarterectomy, there are no descriptions of specific postoperative electrovectorcardiographic abnormalities, including those of myocardial infarction, associated with this surgical procedure.2*4-7 Hultgren et a1.16 recently described acute myocardial infarction in 17 of a mixed group of 50 patients undergoing coronary gas endarterectomy (2 patients), bypass graft implantation (17 pateints) or Vineberg procedures (31 patients). However, no mention was made of the incidence or location of infarction in the 2 subjects who had gas endarterectomy. Of major importance are the clinical implications of electrovectorcardiographic patterns consistent with inferior wall myocardial infarction in our series of patients after right coronary artery gas endarterectomy. Many clinical observations lend support to the proposition that these subjects did not experience transmural myocardial infarction. All patients did well in the immediate postoperative period, and were free of angina pectoris and pain suggestive of infarction. However, lack of classic pain has been documented in patients with postoperative myocardial infarction following both general and open heart operative procedures. 17-lg It is significant that our 9 patients were also free of major arrhythmias, left ventricular failure and hypotension, especially after the 12th postoperative hour. The available postoperative enzyme data are nondiagnostic. Evaluation of serum enzymes after myocardial revascularization is, at best, difficult.16*1g,20 A significant elevation of serum LDH and CPK levels was noted in almost all patients and can be ascribed to the traumatic effects of operation and electrocoagulation upon the chest wall musculature. A previous study has demonstrated significant eleva-
Volume 30
ELECTROCARDIOGRAM
AFTER DISTAL
tion of LDH levels in 37 of 40 patients undergoing cardiac surgery, only ll of whom (37 percent) had any other substantiating evidence of myocardial infarction.20 Other investigatorsl’j have recently demonstrated abnormal SGOT and LDH levels in a significant number of patients who underwent aortocoronary bypass implantation and whose postoperative electrocardiograms did not show a pattern of acute infarction. However, this same group16 found markedly abnormal enzyme values in a vast majority of patients with electrocardiographic evidence of acute myocardial infarction after myocardial revascularization procedures. SGOT levels were transiently elevated above 50 units in 5 of our patients (including 1 subject who did not demonstrate the pattern of inferior wall infarction), and above 100 units in 2 subjects in group I. This elevation of SGOT level may have also been consequent to surgically induced myocardial trauma. Increased levels of SGOT have been previously reported in a series of patients immediately following cardiac surgery, with levels greater than 100 units unrelated to myocardial infarction. lQ It is unlikely that progression of the proximal right coronary obstruction to 100 percent occlusion noted in 4 of 5 patients on recatheterization was based on postoperative coronary thrombosis. Similar occlusion
CORONARY
GAS ENDARTERECTOMY-BENCHIMOL
ET AL.
has been noted before in postoperative patients who underwent saphenous vein bypass alone and has been attributed to the natural course of coronary atherosclerosis or hydraulic effects of the graft, or both.ll Explanation of electrocardiographic pattern of infarction: It is difficult to state with absolute con-
fidence whether these patients sustained inferior wall myocardial infarction. There are 2 possibilities: (1) Mechanical effects of the distal gas endarterectomy may have altered the inferior myocardium in such a manner as to effect these electrovectorcardiographic abnormalities; or (2) these 9 subjects may have had myocardial infarction as a direct consequence of distal gas endarterectomy despite an uneventful postoperative course. If the former explanation is correct, difficulties may arise in the diagnosis of myocardial infarction after gas endarterectomy. If the latter proposition is valid, the significance of such postoperative infarction must be reassessed; both possibilities warrant future clinicopathologic correlation. Acknowledgment We acknowledge the technical assistance of Linda Barton, Nancy Copeland, RN, Mike Dennis, Larry Kuriger, Carole Crevier, Coleen Tallent and Sydney Peebles. The cardiac surgery was performed William Cornell.
by Drs. Lee Brown and
References 1. Favaloro RG: Saphenous vein graft in the surgical treatment of coronary artery disease. J Thorac Cardiovasc Surg 58:178-185, 1969 2. Kaplitt MJ, Robinson G: Appraisal and reappraisal of cardiac therapy. Amer Heart J 81:136-140,197l 3. Kaplitt MJ, Philips P, Pate1 B, et al: Coronary gas endarterectomy. JAM A 215:913-915, 1971 4. Sawyer PN, Kaplitf M, Sobel S, et al: Experimental and clinical experience with coronary gas endarterectomy. Arch Surg (Chicago) 95:736-742, 1967 5. Urschel HC, Jr, Rarruk MA, Nathan MJ, et al: Combined gas (CO?) endarterectomy and vein bypass graft for patients with coronary artery disease. Ann Thorac Surg 10:119-131.1970 6. Urschel HC Jr, Razzuk MA. Miller ER, et al: Vein bypass graft and carbon dioxide gas endarterectomy for coronary artery occlusive disease. JAM A 210:1725-l 728, 1969 7. Urschel HC, Razzuk MA: Reconstruction of the left anterior descending coronary artery. JAMA 218:141-143, 1971 8. Sawyer PN: Direct revascularization with coronary gas endarterectomy. Med 70:1995-1998, New York J 1970 9. Urschel HC, Razzuk MA, Wood RE, et al: Distal CO2 coronary artery endarterectomy and proximal vein bypass graft (abstr). Circulation 42: suppl2:235, 1971 10. Frank E: An accurate, clinically practical system for spatial vectorcardiography. Circulation 13:737-749. 1956 11. Langner P Jr, Okada RH, Moore SR, et al: Comparison of four orthogonal systems of vectorcardiography. Circulation 17~46-54.1958 12. Selvester RH, Haywood W, Griggs DE: The timed vectorcardiogram: a useful clinical tool (as applied to the study of
1,500 subjects). Dis Chest 47:170-l 78, 1965 13. Benchimol A. Pedraza A: The timed Frank vectorcardiogram in the diagnosis of cardiac arrhythmias. J Electrocardiol 2:363-372. 1969 14. Rosenbaum MB, Elizari MV, Lazzari JO: Los Hemobloqueos. Buenos Aires, Paidos. 1968, p 392-395 15. Klein HO, Gross H, Rubin IL: Transient electrocardiographic changes simulating myocardial infarction during open heart surgery. Amer Heart J 79:463-470, 1970 16. Huitgren H, Masahisa M, Buck W. et al: lschemic myocardial injury during coronary artery surgery. Amer Heart J 82:624-631,197l 17. Chamberlain DA, Edmonds-Seal J: Effects of surgery under general anesthesia on the electrocardiogram in ischemic heart disease and hypertension. Brit Med J 2:784787,1964 18. Favaloro RG, Effler DB, Groves LK: Myocardial revascularization by internal mammary artery implant procedures. J Thorac Cardiovasc Surg 54:359-370. 1967 19. Burton H, Greenberg BH, McCallister BD, et al: Serum glutamic oxaloacetic transaminase and electrocardiographic changes after myocardial revascularization procedures in patients with coronary artery disease. Amer J Cardiol 26:135-142.1970 20. Diethrlch EB, Liddicoat JE, Alessi FJ, et al: Serum enzyme and electrocardiographic changes immediately following myocardial revascularization. Ann Thorac Surg 5:195-203. 1968 21. Aldridge HE, Trimble AS: Progression of proximal coronary artery lesions to total occlusion after aorto-coronary saphenous vein bypass grafting. J Thorac Cardiovasc Surg 62:711,197l
October 1972
The American
Journal of CARDIOLOGY
Volume 30
471
ALBERT0
BENCHIMOL,
MD,
FACC
STEVEN D. PROMISLOFF. MD KENNETH B. DESSER, MD
Phoenix. Arizona
Serial electrocardiograms and vectorcardiograms were obtained from 10 consecutive patients who underwent combined proximal right aortocoronary saphenous vein bypass graft implantation and distal right coronary gas endarterectomy. Nine of these subjects manifested postoperative eiectrovectorcardiographic changes of acute inferior wail myocardiai infarction. Only 1 of 13 other patients who were subjected to right bypass graft implantation without gas endarterectomy had similar findings. Ail 9 patients who were subjected to gas endarterectomy and who manifested postoperative patterns of infarction had a clinically uncomplicated postoperative course and were discharged on the 10th to 12th postoperative day. it is concluded that postoperative eiectrovectorcardiographic evidence of acute inferior wail infarction is prevalent in patients subjected to combined proximal right aortocoronary bypass graft implantation and distal right coronary gas endarterectomy. These changes may be based on physical consequences of the gas endarterectomy.
Surgical approaches currently utilized for the direct treatment of right coronary artery disease include aortocoronary saphenous vein bypass, l total coronary artery gas endarterectomy2m4 and a combina5*s No specific electrocardiographic changes tion of these techniques. have been noted after these procedures. Reconstruction of the occluded left anterior descending artery by means of proximal vein bypass grafting and distal gas endarterectomy has recently been described.7 This latter operation has also been applied to the occluded a higher early postoperative paright coronary artery, s-9 providing tency rate than the 70 percent figure cited for total gas endarterectomy. g This paper describes postoperative electrovectorcardiographic changes associated with the combined proximal right coronary artery bypass and distal gas endarterectomy procedure. Nine of 10 subjects so treated manifested postoperative cardiographic signs of recent inferior wall myocardial infarction. From the Institute for Cardiovascular Diseases, Good Samaritan Hospital, Phoenix, Ark. This study was supported in part by the Nichols’ Memorial Fund. Manuscript received January 20, 1972; revised manuscript received March 21, 1972; accepted April 18, 1972.
Address for reprints: Albert0 Benchimol, MD, Good Samaritan Hospital, 1033 East McDowell Rd., Phoenix, Ark. 85006.
466
October 1972
Material
and Methods
Group I consisted of 10 consecutive patients with symptomatic coronary artery disease who underwent combined distal right coronary gas endarterectomy and proximal right aortocoronary artery saphenous vein bypass graft procedures between March 16 and August 19, 1971. In addition, 5 of these patients also had left circumflex or anterior descending artery aortocoronary graft implants. One patient died at operation and was excluded from the study. The patients were all male; their ages ranged from 49 to 62 years (mean 55 years).
The American Journal of CARDIOLOGY
Volume 30
ELECTROCARDIOGRAM
AFTER DISTAL
Group II consisted of !13 consecutive patients who had operative procedures exclusive of coronary gas endarterectomy for symptomatic coronary artery disease. These patients underwent right aortocoronary artery saphenous vein bypass, alone or in combination with aortocoronary saphenous vein bypass to the left anterior descending or left circumflex arteries, between February 19, 1970 and May 6, 1971. The degree and extent of coronary artery disease in this group of patients was similar to that of subjects in Group I. One patient died at operation and was excluded from the study. All patients in group II were male; their ages ranged from 37 to 58 years (mean 48 years). All preoperative diagnoses were based on complete left and right heart catheterization, selective coronary cineangiographic studies, left ventriculograms, indicator-dilution curves and hemodynamic indexes that define ventricular function. The operations were performed under halothane-morphine anesthesia with cardiopulmonary bypass. The technique utilized at our institution for combined distal gas endarterectomy and proximal aortocoronary saphenous vein bypass is similar to that described by Urschel et al.9 Electrocardiogralits were recorded with a Burdick model EK-4 direct-writing electrocardiograph at paper speeds of 25 mm/set. Vectorcardiograms in the 3 plane projections were recorded in the supine position using the Frank lead system.lO The fourth intercostal space was used for placement of the chest electrodes as suggested by Langner et al.rl for the supine position. The vectorcardiograms were recorded with a DR-8 Electronics for Medicine light-beam oscilloscopic photographic recorder using a vectorcardiographic channel (model VET-6). Still and timed vectorcardiograms (running loops) were taken in the frontal, left sagittal and horizontal planes according to previously described techniques.12Js Electrocardiograms were obtained in all patients on the day before and on several successive days after the operation. Vectorcardiograms were obtained preoperatively
PRE-OP.
1 e -1O
/ -co
P
of Postoperative
Electrovectorcardiographic
Group
I
Group I I
IlO.
IlO.
%
%
Inferior wall MI, acute Inferior wall MI, possible reinfarction Inferior wall MI, total
6*
60
1
8
3
30
0
0
9
90
1
8
No changes or ST-T segment changes only
1
10
12
92
*One patient also had acute infarction. Ml = myocardial infarction.
anteroseptal
wall myocardial
from all but 1 patient, who was studied at another hospital. Postoperative vectorcardiograms were available for review in all but 3 patients in group II. These tracings were obtained on the second or third postoperative day in the majority of patients. In no instance were the postoperative vectorcardiograms recorded more than 60 days after the operation, and in no case did the electrocardiographic QRS patterns recorded simultaneously with the postoperative vectorcardiograms differ substantially from those of electrocardiograms taken during the immediate postoperative period. Serial postoperative serum enzyme levels (glutamic oxaloacetic transaminase [SGOT], glutamic pyruvic transaminase [SGPT], lactic dehydrogenase [LDH], creatine
4
. ‘2%
Comparison Changes
+ 20 f
ET AL.
I
POST-OR
‘O.:.:‘”
‘\
TABLE
GAS ENDARTERECTOMY-BENCHIMOL
7/20/71
P LOOP fl ml”.
4
CORONARY
’
;0-
:+--G-+
-
-P
7/30(71 Y-
LOOP
-
I
10A
,,30
\ .
Id
, *,- -::
FP
FIGURE l.Vectorcardiog~rams and electrocardiograms obtained from a 50 year old man who underwent combined proximal right aortocoronary bypass graft implantation, distal right coronary gas endarterectomy and left.anterior descending aortocoronary bypass. FP = frontal plane; HP =: horizontal plane; SP = sagittal plane. The preoperative records (left) show evidence of an old anteroseptal myocardial infarction. Postoperative records (right) demonstrate a recent inferior wall myocardial infarction. Note the change in rotation of the frontal and sagittal plane vectorcardiographic QRS loops from counterclockwise to clockwise. There are prominent superiorly directed QRS vectors, and deep Q waves in leads II, III and aVF of the electrocardiogram, all indicative of a recent inferior wall infarction.
October 1972
The American Journal of CARDIOLOGY
Volume 30
467
ELECTROCARDIOGRAM
AFTER DISTAL
PRE-OP.
CORONARY
GAS ENDARTERECTOMY-BENCHIMOL
8/8/71
POST.
ET AL.
OP.
8/11/71
FIGURE 2. Vectorcardiograms and electrocardiogram8 recorded from a 53 year old man who underwent proximal right aortocoronary bypass graft implantation and distal right coronary gas endarterectomy. The preoperative records (left) show nonspecific S-T segment and T wave changes. Postoperative records (right) reveal changes compatible’ with a recent inferior wall myocardial infarction. Note the postoperative Q waves in leads II, III and aVF. In the postoperative vectorcardiogram there are prominent superiorly directed QRS vectors in the frontal and left sagittal planes. Also note the change in rotation of the frontal and sagittal QRS loops from “figure-ofeight” (preoperative) to clockwise (postoperative). PRE-OP.
E/l0
POST-OP.
/71 P LOOP
e/13/71
P LOOP w
% In”.
u
Y
ml”.
phosphokinase [CPK]) were available for review in 7 patients in group I.
c_ p_ > 10 0
FP
FP
Results
\
c
’
HP
,’
I
’
/
,*’ lmv.
50
QRS ’
’
1 mv. II
I
Ill
-aVR
-J-r-Vl
8YL
aVF
v3
V6
-.--
V3
V6
Vl
FIGURE 3. Vectorcardiograms and electrocardiograms recorded from a 60 year old man who underwent combined proximal right aortocoronary bypass graft implantation and distal right coronary gas endarterectomy. The preoperative records (left) show nonspecific S-T segment and T wave changes. Postoperative records (right) reveal changes compatible with an acute inferior wall myocardial infarction. Note the postoperative appearance of prominent superiorly oriented initial QRS vector forces in the frontal and left sagittal loops of the vectorcardiogram, and the development of Q waves in leads I I, II I and aVF of the electrocardiogram.
468
October 1972
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A summary of the postoperative electrocardiographic and vectorcardiographic changes in both groups is presented in Table I. Group I: Of the 10 patients in this group who underwent combined distal right coronary gas endarterectomy and proximal right aortocoronary saphenous vein bypass procedures, 6 had preoperative electrocardiograms that did not demonstrate inferior wall myocardial infarction. However, in the early postoperative period, all 6 patients manifested electrocardiographic evidence of an acute inferior wall infarction (Fig. 1 to 3). Three of the remaining 4 patients, with preoperative electrocardiographic evidence of old inferior wall myocardial infarction, manifested postoperative changes compatible with reinfarction of the inferior wall. We considered this latter diagnosis to be present on the electrocardiogram when a preoperative qR pattern in 2 of the 3 inferior leads (II, III, aVF) changed to QS and was associated with appropriate abnormalities of the T waves and S-T segments, including a “current of injury” pattern (Fig. 4). On the vectorcardiogram a pattern of reinfarction was considered to be present when there was significant superior displacement of initial 25 msec QRS forces in the frontal and left sagittal planes compared with the preoperative records (Fig. 5). One patient, with normal preoperative electrocardiograms, manifested no QRS changes postoperatively. Group II: The 13 patients in this group all underwent right aortocoronary bypass graft implantation. In addition, 6 subjects had left aortocoronary bypass grafts and 1 underwent a Vineberg internal mammary artery procedure. Postoperatively, only 1 patient showed electrocardiographic changes consistent with acute inferior wall myocardial infarction
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FIGURE 4. Electrocardiograms recorded from a 56 year old man who underwent combined proximal right aortocoronary saphenous vein bypass graft implantation, distal right coronary gas endarterectomy, and aortocoronary saphenous vein bypass graft to the left circumflex coronary artery. The preoperative tracing (upper panel) is consistent with an old inferior wall myocardial infarction. There are Q waves present in leads II, I II, and aVF. The postoperative record (lower panel) shows evidence of reinfarction of the inferior wail myocardium. Note the OS pattern now present in lead I I I, the deepened Q wave in aVF, and the significant loss of R wave voltage in all 3 inferior leads.
PRE.OP.
FIGURE 6. Electrocardiograms recorded from a 46 year old man who underwent right and left anterior descending aortocoronary saphenous vein bypass graft implantation. The preoperative tracing (left) shows left axis deviation of minor degree. The postoperative records (middle and right) show evolution of an acute inferior wall myocardial infarction, with development of deep Q waves and loss of initial R wave voltage in leads II, III and aVF.
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FIGURE 5. Electrocardiograms and vectorcardiograms recorded from a 56 year old man who underwent combined proximal right aortocoronary saphenous vein bypass graft implantation, distal right coronary gas endarterectomy and aortocoronary saphenous vein bypass to the left anterior descending coronary artery. The preoperative tracings (left) are consistent with an old inferior wall myocardial infarction. The postoperative records (right) show changes of reinfarction of the inferior wall. Note the total loss of R wave voltage and development of a QS pattern in leads II and aVF of the postoperative electrocardiogram. Note also that postoperatively there is further superior displacement of the initial vectorcardiographic forces in the frontal and left sagittal planes (initial vectors oriented superiorly for 34 msec preoperatively, for 56 msec postoperatively). The rotation of the left sagittal QRS loop changes from counterclockwise to clockwise.
(Fig. 6). No other patient in this group had significant QRS changes indicative of acute infarction or reinfarction. However, 1 patient did manifest postoperative electrocardiographic changes compatible with transient left posterior hemiblock and right bundle branch blockl” (Fig. 7). Clinical course: ‘The 9 patients in group I who exhibited postoperative electrocardiographic changes
compatible with a recent inferior wall infarction had a relatively uncomplicated postoperative course; none had chest pain suggestive of angina pectoris or acute myocardial infarction. All 9 patients were discharged from the hospital 10 to 12 days after the operation. The remaining patient manifested isolated S-T segment and T wave changes after the operation. On
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onary arteries 2 to 3 months after operation. Of these, 4 had patent right aortocoronary grafts. In 4 of 5 patients, prior 80 to 90 percent obstructive lesions in the right coronary artery progressed to complete occlusion. Discussion
FIGURE 7. Electrocardiograms from a 55 year old man who underwent right aortocoronary saphenous vein bypass graft implantation. A preoperative electrocardiogram (12/l /70) shows nonspecific ST-T changes and a ventricular extrasystole. On the first postoperative day (12/4/70) there are atrial premature beats, right axis deviation, a prominent R wave in lead aVR, rsR’ in lead VI and broad S waves in lead Vg, all suggestive of combined left posterior hemiblock and right bundle branch block. On 12/6/70 the QRS complexes do not significantly differ from those recorded on 12 /I 170.
the third postoperative day he experienced chest pain identical with his preoperative angina1 pain and different from his chest wall incisional pain. His symptoms progressed, and on the 12th postoperative day he was subjected to bypass graft angiographic studies which revealed total occlusion of the right bypass graft at its origin. Enzyme data: Serum GOT, GPT, LDH and CPK values were available for review in 7 patients in group I for at least 2 consecutive postoperative days. All but 1 of these patients manifested a postoperative pattern of inferior wall myocardial infarction. The serum LDH and CPK values were significantly increased in 6 patients. One subject had normal LDH and only minimally increased CPK. SGOT was transiently increased in 5 patients, including a single subject who did not have an infarction pattern on the electrocardiogram. Only 2 subjects had isolated SGOT levels above 100 units. SGPT remained normal in all patients. Follow-up: Five of the 9 patients in group I with a pattern of inferior wall myocardial infarction returned for angiographic study of their grafts and cor-
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Electrocardiographic abnormalities resembling those of myocardial infarction, including abnormal Q waves, have been reported in association with open heart surgery.ls Such abnormalities are attributed to cross-clamping of the aorta, institution of cardiopulmonary bypass, perfusion of the coronary arteries with cooled blood, and localized abnormalities of electrolytes and membrane potentials.ls Supporting the thesis that these electrocardiographic alterations are not due to myocardial necrosis is their transient nature and immediate reversal when cardiopulmonary bypass is discontinued. Electrovectorcardiographic findings of inferior wall infarction described here were noted 12 to 24 hours after right coronary gas endarterectomy and generally followed an evolutionary course. Furthermore, the changes persisted for 2 to 3 months postoperatively in those patients who had follow-up electrocardiograms. Although several studies have dealt with coronary gas endarterectomy, there are no descriptions of specific postoperative electrovectorcardiographic abnormalities, including those of myocardial infarction, associated with this surgical procedure.2*4-7 Hultgren et a1.16 recently described acute myocardial infarction in 17 of a mixed group of 50 patients undergoing coronary gas endarterectomy (2 patients), bypass graft implantation (17 pateints) or Vineberg procedures (31 patients). However, no mention was made of the incidence or location of infarction in the 2 subjects who had gas endarterectomy. Of major importance are the clinical implications of electrovectorcardiographic patterns consistent with inferior wall myocardial infarction in our series of patients after right coronary artery gas endarterectomy. Many clinical observations lend support to the proposition that these subjects did not experience transmural myocardial infarction. All patients did well in the immediate postoperative period, and were free of angina pectoris and pain suggestive of infarction. However, lack of classic pain has been documented in patients with postoperative myocardial infarction following both general and open heart operative procedures. 17-lg It is significant that our 9 patients were also free of major arrhythmias, left ventricular failure and hypotension, especially after the 12th postoperative hour. The available postoperative enzyme data are nondiagnostic. Evaluation of serum enzymes after myocardial revascularization is, at best, difficult.16*1g,20 A significant elevation of serum LDH and CPK levels was noted in almost all patients and can be ascribed to the traumatic effects of operation and electrocoagulation upon the chest wall musculature. A previous study has demonstrated significant eleva-
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tion of LDH levels in 37 of 40 patients undergoing cardiac surgery, only ll of whom (37 percent) had any other substantiating evidence of myocardial infarction.20 Other investigatorsl’j have recently demonstrated abnormal SGOT and LDH levels in a significant number of patients who underwent aortocoronary bypass implantation and whose postoperative electrocardiograms did not show a pattern of acute infarction. However, this same group16 found markedly abnormal enzyme values in a vast majority of patients with electrocardiographic evidence of acute myocardial infarction after myocardial revascularization procedures. SGOT levels were transiently elevated above 50 units in 5 of our patients (including 1 subject who did not demonstrate the pattern of inferior wall infarction), and above 100 units in 2 subjects in group I. This elevation of SGOT level may have also been consequent to surgically induced myocardial trauma. Increased levels of SGOT have been previously reported in a series of patients immediately following cardiac surgery, with levels greater than 100 units unrelated to myocardial infarction. lQ It is unlikely that progression of the proximal right coronary obstruction to 100 percent occlusion noted in 4 of 5 patients on recatheterization was based on postoperative coronary thrombosis. Similar occlusion
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has been noted before in postoperative patients who underwent saphenous vein bypass alone and has been attributed to the natural course of coronary atherosclerosis or hydraulic effects of the graft, or both.ll Explanation of electrocardiographic pattern of infarction: It is difficult to state with absolute con-
fidence whether these patients sustained inferior wall myocardial infarction. There are 2 possibilities: (1) Mechanical effects of the distal gas endarterectomy may have altered the inferior myocardium in such a manner as to effect these electrovectorcardiographic abnormalities; or (2) these 9 subjects may have had myocardial infarction as a direct consequence of distal gas endarterectomy despite an uneventful postoperative course. If the former explanation is correct, difficulties may arise in the diagnosis of myocardial infarction after gas endarterectomy. If the latter proposition is valid, the significance of such postoperative infarction must be reassessed; both possibilities warrant future clinicopathologic correlation. Acknowledgment We acknowledge the technical assistance of Linda Barton, Nancy Copeland, RN, Mike Dennis, Larry Kuriger, Carole Crevier, Coleen Tallent and Sydney Peebles. The cardiac surgery was performed William Cornell.
by Drs. Lee Brown and
References 1. Favaloro RG: Saphenous vein graft in the surgical treatment of coronary artery disease. J Thorac Cardiovasc Surg 58:178-185, 1969 2. Kaplitt MJ, Robinson G: Appraisal and reappraisal of cardiac therapy. Amer Heart J 81:136-140,197l 3. Kaplitt MJ, Philips P, Pate1 B, et al: Coronary gas endarterectomy. JAM A 215:913-915, 1971 4. Sawyer PN, Kaplitf M, Sobel S, et al: Experimental and clinical experience with coronary gas endarterectomy. Arch Surg (Chicago) 95:736-742, 1967 5. Urschel HC, Jr, Rarruk MA, Nathan MJ, et al: Combined gas (CO?) endarterectomy and vein bypass graft for patients with coronary artery disease. Ann Thorac Surg 10:119-131.1970 6. Urschel HC Jr, Razzuk MA. Miller ER, et al: Vein bypass graft and carbon dioxide gas endarterectomy for coronary artery occlusive disease. JAM A 210:1725-l 728, 1969 7. Urschel HC, Razzuk MA: Reconstruction of the left anterior descending coronary artery. JAMA 218:141-143, 1971 8. Sawyer PN: Direct revascularization with coronary gas endarterectomy. Med 70:1995-1998, New York J 1970 9. Urschel HC, Razzuk MA, Wood RE, et al: Distal CO2 coronary artery endarterectomy and proximal vein bypass graft (abstr). Circulation 42: suppl2:235, 1971 10. Frank E: An accurate, clinically practical system for spatial vectorcardiography. Circulation 13:737-749. 1956 11. Langner P Jr, Okada RH, Moore SR, et al: Comparison of four orthogonal systems of vectorcardiography. Circulation 17~46-54.1958 12. Selvester RH, Haywood W, Griggs DE: The timed vectorcardiogram: a useful clinical tool (as applied to the study of
1,500 subjects). Dis Chest 47:170-l 78, 1965 13. Benchimol A. Pedraza A: The timed Frank vectorcardiogram in the diagnosis of cardiac arrhythmias. J Electrocardiol 2:363-372. 1969 14. Rosenbaum MB, Elizari MV, Lazzari JO: Los Hemobloqueos. Buenos Aires, Paidos. 1968, p 392-395 15. Klein HO, Gross H, Rubin IL: Transient electrocardiographic changes simulating myocardial infarction during open heart surgery. Amer Heart J 79:463-470, 1970 16. Huitgren H, Masahisa M, Buck W. et al: lschemic myocardial injury during coronary artery surgery. Amer Heart J 82:624-631,197l 17. Chamberlain DA, Edmonds-Seal J: Effects of surgery under general anesthesia on the electrocardiogram in ischemic heart disease and hypertension. Brit Med J 2:784787,1964 18. Favaloro RG, Effler DB, Groves LK: Myocardial revascularization by internal mammary artery implant procedures. J Thorac Cardiovasc Surg 54:359-370. 1967 19. Burton H, Greenberg BH, McCallister BD, et al: Serum glutamic oxaloacetic transaminase and electrocardiographic changes after myocardial revascularization procedures in patients with coronary artery disease. Amer J Cardiol 26:135-142.1970 20. Diethrlch EB, Liddicoat JE, Alessi FJ, et al: Serum enzyme and electrocardiographic changes immediately following myocardial revascularization. Ann Thorac Surg 5:195-203. 1968 21. Aldridge HE, Trimble AS: Progression of proximal coronary artery lesions to total occlusion after aorto-coronary saphenous vein bypass grafting. J Thorac Cardiovasc Surg 62:711,197l
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