ospital, University ol’ North Carolin;~ at Chapel Hill. North Carolina. This study was prewnled in part ;a~ the 61~1 Amwl Scient~lic Session of the American Heart Associstion. Washingkm. IX.‘.. Novembci I!%B. It tvas supported in parI by Granls 1-IL-!7430 iWl

National lnstitutcs of Ncalth. Bethesda. Maryland. M;I wwc IlUnil~d ad

iu9alyzed using CUNFO data mitnagcmCl9l and analybk systems of lbe University of North Carolims at Chapel Hil! (RR-46 G.C.II.C.1 wpportcd by the Division of Research Resources of the Nakm;d Lndtuks of Hdlh.

Manuscript received July 5. IYHY: reviscd manuw’ipt received November I. I ber 9. 1989.

Avanindra J;lin. MD. Cardiac Calheleriralion Lab-

oratory, Memoial Hospital. Chapel Hill. Nod Carolina 27515.

C 1990 by the American College of Cardiology

JACC Vol. IS. No. 5 April 1990~ 1007-I I

Table 1. Clinical and Angiographic Characteristics of the 37 Patients Undergoing Coronary Balloon Dilation

Men Women Mean age (yr) No. of patients with previous infarction Mean no. of medications per patient No. of patienls receiving calcium

antagonists

21 (57%) 16 (43%) 56.8 (range 38 to 741 27 (73%) 2.3 (range I to 3) 34

No. of patiems receiving beta-blocking

No. of patients receiving nitrntes Bieclron fiwlidn (%I

ii, eP vessels diluted

I?

14 51,4 (rung 31 10 74) 43

ECG machine (Marqucttc). Llasclinc recordings were ob- toincd before balloon inflations,

T/W nnflicJplcl.sl!: brllloot~ crrrhercr N’NS hw dv(ltlw~ md pm’tiotwl (II the ,wttosis. The number of balloon intlations, duration of each inflation and the pressures utilized were determined by the operator on the basis of angiographic appearance of the vcsscl before and after each inflation. The unipolar intracoronary elcctrograms and the body surface leads were recorded during balloon inflations of up to I20 s and until the ECCi signals returned to the baseline after balloon deflation. Forty-three coronary artery segments were dilated in these 37 patients.

on. The unip~~lar clcc- were evaluated for the

prcscm.3 ati absence of ST segment deflection and the presence of G WOI::C E, The maximal ST segment change was determined 40 ms l~~c !.‘rc J point. A negative U wave was id~nti~~d if thcrc was a &;i’;‘tc ncybztivc dcfl ’ the TP segment. A positive I$ qa::~ was iden

sitive dejection &&in the T The clinical an&qzrqhic charac- tients undcq coronar~~I~~~~~~s(y

are shown in Table I. None of the patients were rettivirrs dipxin or antiarrhythmic agents. Previous myocardial ur’ hrction was documented in 27 patients, and 28 patients underwent balloon angioplasry of a vessel supplyiq a hy- ~ki~~tic or ~kin~tic rny~~~ial segment.

plasty, Fort~th~c coronary arteries were dil ilations were ~erforn~ed of the lefr untcrior de- scending coronary artery in 20 patients. the left ci~urn~~x c~~~~y artery in 7 patients, the right coronary artery in i I

ients and a diagonal analysis, the ramus

rrzumflex artery, and grouped with the left anterior

descending artery. Thus, dilation was performed in the

N=ll

distribution of the ileft ~~~tcrior de patients, the left circumflex artery ia

all vessels. ST sternest elcvatiun de of 40 vessels and averaged 8.6

devc~o~cd during vcsseQ dilation in three patients. New U waves. New positive or negative U waves devel-

oped on the intracoro~ary electro during balloon dila- tion of 30 vessels (70%) (19 of 23 left anterior desce~di~ coronary arteries, ‘7 of9 left ci~~mflex coronary arteries an 4 of I I right coronary arteries). The ld waves were transient and resolved with de~ation of the battoo~ and ~sat~tio~ of the ischemia. New negative U waves were observed during dilation of 12 vessels (7 of 23 left anterior descending arteries, 4 of 9 left circumflex art es and I of 1 I right kx~x~y arteries), and new positive waves occurred with dilatio& c$ :,P vessels (I2 of 23 left anterior descending arteries, 3 al= ‘I, left circumflex arteries and 3 of I I right coronary arteries) IFi. il. There was no significant differ- ence in the incidence of nW IJ waves during dilation of the left anterior descending or the IeR dfcumflex artery (26 of 32): the incidence was lower (4 of I I) tiring dilation of the right coronary artery (p s: 0.02). Figures 2 to 4 show, respectively, an intracoronary eleclrogram with a negative W wave recorded during dilation of the right coronary artery and with a positive U wave and no U wave recorded during dilation of the left anterior descending artery.

Correlation with ST segment changes ( opmenl of a negatitre U wave was associated with ST segment elevation in all patients; the elevation averaged 12.8

Figure 3, Baseline intracoronary elec- trogram (IC) and surface lead II and V,

) from a patient with a new positive ‘U wave (right) associated with 6 mm ST segment elevation during left anterior descending coronary artery balloon dilation (arrow).

JACC Vol. 1s. No. 5 April 19W 1007-I I

Figure 4. Baseline intra~o~aary elec- trogram (ICI and surface lead II and V,

the body surface EC0 du ’ exercise is reported (2) to occur in <I!% of routine t mill exercise tests. This has

iatad with significant proximal left anterior de- or left main coronary artery stenosis (2). The r this association is unknown. etion of U waves with site and magnitude of ische=

mia. We observed the development of a negative U wave on the intracoronary electrogram during balloon dilation of 12 (28%) of 43 coronary artery segments. Although the inci-

e of negative U waves was lower during dilation of the was no difference in the inci- ft anterior descending and left

es. These Andings indicate a lack

when no U wave changes 0.0001). This association was evident regard-

S. ST segment (SEX8 change (mm) during balloon inflation of ~scls resulting in new negative (NEG)

b U U waves, new positive

waves and no new U WBIV~S.

80

1 P-NO ,-

ur faiiure to observe new ne

surface ECG leads. These findings s

the absence of diagnostic ST segment changes on monitored leads CC5 and aVL during exercise treadmill testing in 8 of

27 patients with significant coronary artery disease. finding of an apparent lack of correlation between negat waves and the magnitude of ST segment change on the body surface ECG is different from our fin nary electrogram. We observed that t segment change did correlate with the development of both positive and negative U waves. This difference may repre- sent the relative insensitivity of the body surface ECG in

main cor~~a~y artery. arher, they suggest that

positive U waves on the intra-

tive U waves were unexpected fiadi~~s and have not been previously reported. These data suggest that the genesis of

. Cole JS. Surawicz B. Negative U WPW: a highly specific but poorly understood sign of hrart disease. Am J Cardiol 1982:49:2030-6.

2. Gerson MC. ~‘~~~~~~~~ JF. orris SN, McHenry PL. Exercise-induced U-wave inversion as il 8Wrkcr of sb2nosis of the left anterior descending COlUWi’~ nIlcry. Circulnrion IY7Y:SY: 1014-Y.

3. Cierwn MC. McHenrv PL. Re$tinc IJ wave inversion iis ;I marker of r!cnosi? of lbe hzfl i;nterior ck&nding coronary wlery. Am J Mcd IYliO:h’~: F4S-SO.

I;eldrl~~lll T. CbuiI KG. Cbildcr$ RW. R vavc oflbc w&e and inlrucnr- onijry elcclrogram during i~cule coronary ;n-{cry occlusion. Am J Cerdiol 19X6:58:885-90.

Feldman T. Childerb RW. Chua KG. (dptirnal ECG monitormg during percutaneous transluminid coronary angioplasly of the left imterior de- scending artery. Cathe~ Cardiovasc Diagn 1987;13:271-4.

Walanabe Y. Purkinje repolerizution us a possible cause of U wwcs in the eleclrocardiogram. Circulation 1974:51:1030-7.

The U wave ;rnd aberrenr inrruvcntricular conduc- tion: further evidence for the Purkinje repolarization theory on the generir of rhe U wave. Am J Cardiol 1978:43:?3-31.

Lepeschkin E. Gene,:s of the U wave. Cwulation lY57;15:77-Xl.

Schechtcr E. Freeman C. L;lrrarii R. Aficrdepoluril.aliun a!+ a mcchanibm (or the long Q’!’ syndrome: clectrophy~iologic atudics of a case. J Am Coil (‘indiol lYHd:3:145h-61.

Carubouef E. l9eroubnix E. Coulombe A. Acidosis induced abnormal repol;rriLulion and rcpelitive activity in isolutcd dog Purkinje libers. J Physiol 1980:74:97-106,

Lab MJ. Contraction-excitalion feedback in myocardium: physiolo&ic basis and clinical relevance. Circ Res 198X0:757-66.