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JACC Vd . 19, Ho. J 1sr.u.ry €975 :731-s
Maximal Voluntary Exercise Variables in Children With Postoperative Coarctation of the Aorta SCOTT M . BALDERSTON, MD, ELAINE DABERKOW, RN, MSN, DAVID R. . CLARKE, MD, FACC, ROBERT R, WOLFE, MD, FACC
Denver, Colorado
Thirtyon children with Postoperative coarcutlon of the aorta underwent maximal graded bicycle ergomelry, mmost; an eleclroaiGb' braked ergmneter and the James protocol; IR also under . went cxpir:ury gm measurement mhrg a mass spectrometer . Twaly4we age- and gender-matched normal subjects were used m a entrol group. Tie attam age at operation was 41 months and
the man age at evaluation was 134 months (man follow-up
measured, maximal oxygen eonalmplkn was 89% of predicted value with an anaerobic threshold as 43 s 3.5% of exercise time.
The observed work variables were not different from values is the control group and were not affected by the type of repair or menu peak systdk blood pressure was 152 : 7 .6 am Hit versus 147 ± 5.7mm hg Ira the central greer y= ik9). Padnuwhohad associated m1ratardite breast toad algalificaaty lower maximal
interval 93 mouths). The original surgical repair was arbdaviua Gap repair h R patients, end to end sentiment ; in 21, patch aortaplarty In I patient not tubular graft in 1 . Patients exercised until exhaustion ark makimal exercise snarl. mbles wave obtained. rr, was3ns. voluntary peak hart rate was 113 hert'ro:a: (3f .6% of predicted value), Indicating excellent ehort. Minor power was 111% of predicted value and, whoa
oxygen censor ;pdou IRS s 3% en. 98 s 4% of predicted value) .
Although surgical repair of coaretation of the aorta has proved to be a lifesaving procedure bath io infants and in older children, early and late postoperative complications eventually plague a large number of here patients . Abnormal left ventricular function in patients who have had surgical repair of coarctation of the aorta has creel previously reported (1-3). Systemic hypertension at rest and during exercise has also been frequently noted (2-7), as has a high incidence of recurrent es :etathw (3,9) ; a rather pour prognosis far long-term survival was noted in earlier reports (2,4) . Improved surgical techltiques and earlier recognition
coaretation of the aorta. There were 22 male and 9 female children, ore of whom had Turners syndrome . The mean age at operation was 41 months (range 3 days to 13 years) . The mean age at exercise evaluation was 134 months (range 7 to 17 years) with a mean follow-up interval of 93 months . Forms of surgical repair included end to end anastomosis in 21 patients, subclavian flap repair in 8, patch aortoplasty in 1 patient and tabular graft in ! . Six patients underwent additional operations for relict -jf recerrent obstruction ai the coarctation tire before exercise testing, and four other patients required surgical treatment of aortic or sahaordc
and repair have brightened the outlook after coaeclalion
stenosis. The control group consisted of 22 normal children matched for age, wader and body surface area. Blood pressure meamremeafs- Blood pressure was measured with the patient seated I min before exercise, at [-min intervals doling exercise and at 1-, 3- and 5 •ndo intervals after exercise. The largest cuff that would At over the right upper arm was used, including leg cuffs (18 cm) and cuffs for children (10 cm), adults (12 cm) and large adults (16 cm) . Simultaneous right arm and right leg measurements were made with the patient supine before and immediately (within 30 s) after completion of exercise. Pressures were measured before, during and after exercise with a programmed electrosphygmomanometer (Narco-Biosystems P300) at an inflation-deflation rate of 10 to 12 .5 s. Inflation and deflation were performed electronically with the investigator manually determining systolic and diastolic blood pressure through microphone augmentation of Korotkoff sounds .
repair (10-12). In this study we report the exercise capacity and physiology of 31 patients who underwent maximal voluntary exercise testing a mean o'93 months after repair of eoarcuhon of the aorta.
Methods Study patients- The study group consisted of 31 children who returned for exercise evaluation after surgical repair of
From the Ueivershy of Colorado Health Seances Center and the Children's Hospital. Deaver, Colorado . Manuscript received May 7,1990 ; evis :d manuscript received May 22, 1991 . aeepted June 15, 1991. Addrrts for wname : Robert R. Wdfe . MD, Pediatric Cardiology, The CbMen's Hospital, East i9th Avanae, Denver . Colorado 00291. 01992 by the A-
CalkgcofC.,dioioxy
the mutes suggest that adequate cardiopulmonary faaWeo, normal or above average work apathy and normal exercise systole blood Pressure call be adlained in eh8drea with muting. toy repair of cwrcmtlan of the amts performed before school age. (JAm Coil Cnrdrol 1992;19:I54-8)
0735.10970V53 .50
MCC V.I . 19. No . 1 nanvary 1992 :154-a
BALDEIRSTON ET AL . EXERCISE CAPACITY AETERCOARCTATION REPAIR
Tale 1. Results of Exercise Tests: Patients With Coarctation Repair Versus Control Patients Pawn, With Cwslativn Repair in-31) BSA(n1 ) Maximal HR Ibealundal Rest syu0ut BP I .. He) Peak aYawlie BP (am Hgl Mean power1u'i M^anal VO_ (M1to per mia) Anaerobic tIfeshold
1 .18±0 .05 183 _ 2195% PV) 1I I a 4.7'
155
Table 2 . Results of Exercise Tests Anal zed by Age at Initial Coarctation Repair' 1n=101
Age r' I Year in 21)
thi _ 3195% PV) 10619
182 0 5 (9496 PV) 113 ± 4
154 t 15
151 ± R
An < I Year
Control Paielns in =22) 1 .2±0 .07 189 ± 3 (96%% PV) (m 0 3 .5-
_
Maximal HR (bnadmin) Rest syslds 8P (mm Hg( Peak systolic HP Inuit Hit,
152 '
7 .u
147 =_ 5 .7
73 a 4 .71110± PV1 41 *_ 1 .' 00M, PV)
71 a 61122% PV1 49 ! 2.1 (92% PV)
63 - 3 .5
62
2 .1
Meanpower(WI Arm-leg gradient (mm Hgil Reonerationlm, .l Age al exercise (m0l
74±9(112%PV) 25 ± 5
4410 135 z 9.6
154 z 12
20(21
All -.1-m
1% ET)
mean
All values are n an values a SD. -p c 0 .05: an when differences an vmitram. BP = blood pressure; BSA = body sudxe aura ; ET = me,
73 ±7 (109% PV) 30 s 13
meats tatter z SD . All differences are not siad6cam .11 = ale esereise our-leg pressure paairm . Abbreviations as in Table 1 .
^or ,se
tine; HK = heart rate: PV = predicted value ; V0, = oxygen upake .
Exercise testing . All patients exercised to exhaustion on an electronically braked cycle ergumeter tijumton model 845, Qulnlon Instruments) with continuous graded workload according to the protocol of lames et at . (13) . Arm blood pressure and 12-lead electrocardiograms (ECGs) were ohtained every minute, with continuous manicuring of heart rhythm by oscilloscope screen . Arm and leg blood pressures were obtained immediately after exercise. Eighteen study patients also underwent continuous breath by breath expiratory gas analysis utilizing a mass spectrometer (Medical Gas Analyzer model 1100, Perkin-Elmer) after a stable base :ine value was obtained. Breath by breath recover' gases were measured for I min . Gases measured included expiratory oxygen and carbon dioxide . Minute ventilation, tidal volume and breath frequency were also measured and the ventilatory equivalent of oxygen and carbon dioxide was calculated . Data aodysis. Results of exercise tests me expressed in absolute units and as a percent of the predicted value for each patient, and are summarized using percent of predicted values derived from the study of James et Al. (13) . Predicted values for oxygen consumption were derived from those reported by Astrand and Ryhming (14) . Descriptive statistical variables were derived by standard methods . Study group variables were compared with control group variables with use of a one-way analysis of variance . Differences were considered statistically significant at p < 0.05 . The anaerobic threshold was expressed as a percent of exercise time because it correlates better with performance in children than does maximal percent oxygen uptake or power output (15,16).
Results Rxerdse variables (Table 11 . Table I shows the exercise variables for the study and control groups . There is no
significant difference between the groups with respect to any of the measures of exercise capacity, oxygen consumption, anaerobic threshold or blood peessur . However, several patients in the study Proof did `a.: a peat blood pressure higher than the norms for their age (16), and rest blood pressure was also slightly higher for the study group. Of six patients with exercise hypertension, four had a postexercise mm-leg pressure gradient >40 mm Hg, one a 30 mm Hg gradient and one a 20 mm liggradient . Two of these patients had no measurable gradient at rest but had a postexercise gradient of 30 and 50 mat Hg, respectively . Two additional patients had a mild gradient after exercise only and Due had a 27 mm Hg gradient at rest that increased to 50 mm Hg during exercise, but nave of these three patients had significant hypertension. The remairli .ro 22 patients had no rest or postexercise gradient. In patients with a rest gradient, the gradient increased an average ol2 to 4 times the rest value after exercise. For ire study group, the meant maximal voluntary peak heart rate was 183 beatlmin (94 .6% of predicted value), indicating excellent effort . The maximal voluntary work was 120%, the mean total work was 131% and the mmn power was 111% of predicted value . The mean maximal oxygen uptake was 48 mIkg per min (g9% of predicted value) with an anaerobic threshold at 62.7% of exercise time. Rek of age (Table 2). When the patients were analyzed by age at initial repair, Ihnee was no difference for any of the variables between the group whose initial operation was performed before 1 year of age and the group with later repair. Although not statistically significant, there was a trend toward more frequent need for reepetalion in patients whose initial operation was (performed before 1 year of age (40%) than in patients operated on later (9.5%) . Role of type of surgical repair and awae6ted ddects (Tables 3 and 4). When the study group was subdivided according to the type of initial repair (subclavian flap vs . end to end anastomosis), there were no differences in the exercise variables between these two groups (Table 3) . However, none of the patients with subclavian flap repair, compared
156
BALDERSTONET AL t1ERCIOE CAPACITY
1ACC Vat . $9 . No- I
APPFB COAR(TATION REPAIR
I-ry 1492IL-8
Table 3, Main of Enerctse Tests Analyzed by Type of INlial Coaretatlon Repair So"- Flap to=e1
Manual HR tbeealminl Pest spslnbc UP 4- HS) Peak sytrtie By loan Hg) MeanpoaerIW) Maaimi Voa imb12 per
Ian ± 2.B (919 PV) 101 3 116 e H 5706 (110a3 .5RPV) 50 n 1(93 ± 2A% PV I 1? ' 6
F M to Nod
In-21) 185 -- 4 (9555 PV) 11616 157 a to 73 z5 (1I0S4 .1%P\ 41 ± 2 (96 v 4% PV I 30 s I
sin) Armnlet earliest tmln Ha) Reopetalion (nn .) 0 orx 5 of 21 age at mrair (no) 22 0 at 140,_9, .age ore rwarka anal IM ± 9 14a All vaa,a are nov a oaks, t SD. 'P 10.01; tp = 0 .03; an alter dincwnres are roe sipnificanl . Abbreviations as ie Table 1 .
teal--ion,
with 5 (24%aj of 21 of the patients nlth end to end repair, required reoperation (p < 0 .01). Finally. the patients with coarctalion alone were compared with those who also had a ventricular septat defect or aortic stenosis, and there were no differences in the exercise variables between these two groups (Table 4). Patients in the complex lesion group were younger at initial operation (13 vs . 50 months) .
recurrent coaretation and subsequent cardiovascular disability. The utility of exercise testing to assess the results of coarctation surgery has recently been emphasiecd (27). Posluperalive hypertension . Maron Its al. (2) reported the
long-term follow-up of 248 patients who had surgical repair of coarctation of the aorta . Their discouraging study revealed a 78% incidence of residual cardiovascular disease in survivors . including a 37% incidence of rest hypertension and a 12% incidence of premature cardiovascular death . A third of their patients were operated en after age 25 (morn age at operation 20 yearcl and the majority of cardiovascular deaths were in those with initial repair after age 25 . These results clearly demonstrated that the noutsurvivors had expeflcnced a longer period of preoperative hypertension than
Discussion
Residual nbourmalllies altar avavctadml repair . Previous reports have indicated that residual kit Ventricular abnormalities may persist long after surgical repair of cnarlualion oftheaortaaed may he related to residual hypertension (17) . renin-engiotenssrr overactivity (I8), elevated levels of circulating catecholamines (19), altered barnrecernor reflexes (20,21), altered arterial impedance to pulsatile How (22-24) or associated condmted cardiomyopathy . Left ventricular uypertrophy and hypericmevia have been found years after coarctation surgery (1,25 .26) . The practical significance of these findings is unknown, although it is suspected that left ventricular hypertrophy and myocardial mass-perfusionmismatch may contr;~,Ate to the early development of ischemic myocardial disease in patients with repaired coarctation (I). Other significant reported residua are postoperative hyper-
had the survivors . Mason et Al . (2) also reported that 46% of
patients had a postoperative blood pressure that was the same as err higher than that preoperatively . Subsequent reports (7,10,17 .24) have confirmed that when coarctation of the aorta is repaired after the neonatal period, the earlier the repair the greater is the reduction in blood pressure (24) and the lower is the incidence of postoperative hypertension . In our series, all patients had initial repair of coarctation of the aorta before 13 years of age and most before 6 years of age- However, the group contained a mixture of patients
Table 4. Results of Exercise Tests Analyzed by Initial Lesion and Presence of Additional Congenital Lesions Canal 1n -. 24) Maximal HR (bs.Wnio) Rest systolic BP Imm Hal
Peak sFttnik RP (mom 11e1 Mean Power (w) Memos) vu,lna Per mint A--kg gradient lmm Hg) Reoperadon t-1 Age at inatat apeir cowl
183 _ 3 112 x 4 159 t e 77 x 61117 + 125 PV) 49 )9d ± 4'6 Pv) 30 = e
4 of 24 $0 a ft
Ccarcl + AS ar VSD 1n=73 I0 M x 4 10B' a 130, 5
60 6(105 ! 415 PV) 41 (85 - 3% PVI t6 a 4 297 13 5 8t
All vaau, are mesa awes x St) Ip = 003; Ip < 0.91 : all oiler Merences are not drnitlcael. AS = sonic necrosis; Coarct=cwrclation; VSD - v,a,6, .kr Plat 4.1.1; other abbaviati,as ns is Table I.
IACC . 19, No. I laeevy Vol1992:154-I
who underwent repair during and after the neonatal period, groups that have been considered separately in most previous studies (8,9,12.1'1,2) . It should he noted that the patients in this series represent only those who have returned for exetcisc testing at this institution and not the entire group of patients who underwent surgical repair daring the study period . Although six patients in the study group had exercise hypertension, the mean systolic blood pressure fur the study group was not significantly greater than that of the control group. Of those six patients, four had a significant arm-leg pressure gradient. Thus, it appears that the maturity of patients operated an early in life can be expected to have normal blood pressure and that postoperative hypertension is most often related to residual or recurrent coarctation . Exercise variables . The results indicate that normal exercise variables are found and can be expected in patients after early repair of coarctation of the aorta . Indeed, the prrformance of the study patients was slightly above normal, a finding that may be related to the previously described elevated levels of catecholamines in patients with coaretation (29). Left ventricular function was not assessed directly in this study but its adequacy was inferred from the exercise rapacity. Exercise variables did not differ significantly in relation to age at operation. One might anticipate that a longer duration of coarctatioo would cause more left ventricular damage, as has been shown (10) in patients undergoing repair at ages rider than those of the patients in this series . However, we found slightly better performance in patients who underwent repairafter I year of age . perhaps because the more severely affected patients presented at a younger age and had a higher incidence of complex disease and recurrent obstruction (8 .9,19). Additionally, in our series the oldest patient age at
initial repair was 12 .5 years, which is a relatively young age compared with that in many series . It was incidentally rioted that of the six patients who had undergone reoperation for recurrent coarctation, five had end to end anasbmosis as the initial repair (four were < I year of age at initial operation) and time had suhclavian lisp repair as the initial repair. Coodagalu. Patients who had undergone surgical repair of coarctation of the aorta at an early age have normal maximal voluntary exercise variables. Their rest and exer. cise systolic blood pressures are also usually normal. These findings are similar to those in the more recent published series (11 .17,19,30). which tend to include a ma crity of patients who aladerwent repair in the first 2 decades of life in contrast to earlier studies that i.auded many patients operated on as adults . Patients with exercise intolerance or exercise hypertension tended to have significant residual or
recurrent structural abnormalities requiring surgical intervention . It remains to be seen what the long-tern history of the patient with postoperative coarctation will be with regard to adult onset hypertension and coronary artery disc L,: . Re the aorta cntkmk for young people with euorctatior
BALOBR5111N CC AL, EXERCISE CAPACITY ArlER COARCLATI VN RCPAIIs
157
operated on early in life is considerably brighter than that
of
patients reported on 2 decades ago .
We
tbaek Debra S. Olheme for editorial and seoturiat expertmse.
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