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Echocardiographic estimation of critical left ventricular size in infants with isolated aortic valve stenosis
l
Lt f Y
IU.1 mm had an angiofrrphic Icfl vcntncular end-diastolic volume of 22X cc/m’. A left venWtlar end-diastolic diameter a aigmficant prcdiclor of death ip < 0.01). Correcting this lcfi ventricular end-diastolic diameter for body ~~~rfw the paixnr budy
area mow
clearly
with ndiameWrof
SKI’WZ
xca
was
explains
the good outcome
IO.1 mm because the
smallest
in the
in
lhis patienl’s
study. This improve this
corrcwion. howvcr. dots not statistically measurcmcnl a5 a predictor of morlahty. rWi!rci/ rnfrc rrnrrfrr.\tfirrw/rr showed considerable overlap berween suwivors and nonsurvivors (Fig. 4). This variable ww nut a predictor of survival. Angiagraphic ventricular w&unes Wig. 51. Lcfl ven!ricular volume dnla were available for review in 17 patients. The mean left ventricular end-diastolic volume index in the surwvor~ (43 ccfm’l was greater than that in lhe nonsurvivort III cc/m”) Lp < O.uOIt. In Ihe group with meutured vohimc~. all of the swwxs had a lctl venuicular cnddiastolic volume index >?O cc/m’ and an ahsolute end-
diastohc
volume
>4.5
had a left ventricular
cc (Fig.
51. Three
of the swvivors
end-diastolic volume index of 20 to
?S cc/m’: no patient wilh a measured index ~20 cc/m’ (n = 5) survivedand an index 120 cc/m’ was a significant predictor of death (p < 0.01). There was no difference in the angqraphically
delermined
ejection
fraction
between
the
groups. There dala arc Gnilar to those previously reported. which included patients 56 momhs of age IQ. Echocardiagrsphic eslimate of left ventricular volume (Fig. 61. In comparing the two-dimensional echocardiographic area meawremcnts and angiographic left ventricular volumes in patienls wth both of these measuretncnts available, a wry good currclalion i% obtained by using the log of the left ventricular end-diastolic volume lr = 0.97). There is also a eood correlalion tr = 0.94) when linear regression is used. A comparison of M-mode left ventricular end.diasw!ic diameler and log of the left ventricular end-diaalolic volume was albo performed. This showed a slightly paorer correlation coefficient of 0.88 and a wdcr scatter. Patients <2 weeks of age. In comparing survivors (n .= 81 and nonwrvivors In = 71 among those patients undergoing vslvotomy before 2 weekr of age (Table 2). the previously
two
&quake fur burvival after valvotomy and who wou!d therefore he candidates for u Norwood procedure or heart transplantation. In 1981. Latxu~ et al. (13) cvaluatcd two echocardiographic criterld for da diagnosis of hppoylaslic left venlr~ule and demonstrated that a measure offeft ventricular cross-sectional area was successful in predicting survival.
Table 3. Uwftil Echocardiographrc Crneria in the Wagno+ Hvpu&rtic Len Ventricle in Critical Ann;c Slenosi?
of
They also apphed this criterion ID five infants with aorlic stcnos~s. hut the miljority of these infants had an enlarged and there ~crc no angiographic lcti ventricular volumes for comparison with the cchocardiographic measuremenls. The present study. This study revealed that the survivors of valvotomy. in addition to having a larger left ventricle. were also older at operalion than the nonsurvivors but did not differ in body weight or sulfaee area. These data are cunsislenl H ilh the premise that the left vcnlricle in six of rhe seve nonsurvivors was not sufficient to support the systemic circulatio,l. Thus. these patients wobld have presented at an earlier age. as soon as ductal constriction became manifest. This study also demonstrates that both an M-mode mcasurcment (left ventricular end-diastolic diameter) and a Iwo-rhmensmnal echocardiographic measurement (left ventricular cross-sectional area! can be used IO estimale left ventricular volume in this group of patients. The latter meaturement is of more value in assessing the size of the left ventricle in this patient group with a steeper curve and less scatter in the region of mosl interesr II .S to 8 cc). especially using logarithmic regression (Fig. 6). In our group of patiems. a left ventricular cross-sectional area ~2 cm2 as measu~-ed on the long-axis echocardiogram successfully identified all four patients with a left ventricular end-diastolic volume index <2il cc/m’ with no false positive or false negative results. One additional patient had a left ventricular cross-seclional area of 1.2 cm’ with no angiographic volume determination and this patient did not survive. Latson et al. (131 measured left ventricular crabssectional area in I9 normal infants aged 5.5 + 5.1 days and weighing 3.1 +_0.4 kg; the mean value was 2.65 cm’ + 2 SD. dclining a normal range of I .S to 3.5 cm’. None of the normal infants had a value <2 cm?. but all infants with a hypoplastic left heart had a YBIW
J
ventricle
because
septal
bowing
from
right
to left leads
to
of left ventricular size. Mitral aqulus size was also smaller in nonsurvivors. but there was considerable overlap of this variable between survivors and nonsurvivors (Table Il. Ludman et al. (22)
significant
found
underestimation
the mitral
anulus
in control
neonates
to average
IO +
3 mm, with one value of1 mm and two of 8 mm. We do not
consider this variable useful unless it is extremely small (56 mm). There are obvious problems with basing treatment up tions on any single measurement such as echocardiographic left ventricular size. This measurement only scrvcs as ancillary supper, for or against surgical valvotomy and should be considered only as a part of the entire clinical presentation. In addition. considerable care should be taken in performing the echocardiogram to ensure that the largest end-diastolic left ventricular image is recorded. Balloon valvuloplasty. The success of balloon valvulm plasry in some investigations (22-26) has made it an attractive alternative technique for selected patients. Zeevi et al. (261 recently compared balloon valvuloplasty with surgical valvotomy in two groups of I6 consecutive infants and found left ventricular size to be a risk factor for early death in both groups. There were eight patients (three surgically treated, five balloon-treated) with a left ventricular end-diastolic volume assessed by angiographic volume measurcmcntn 564% of the predicted value: only one of the eight survived. The survivor had a volume of4l% of the predicted value and was alive al 6 months after two balloon dilations. No follow-up ecbocardiognphic or angiographic data for left ventricular size were available. Clinical and echoeardiographir operative wcee~s. Echocardiographic criteria lhat we consider useful in management decisions regard& the diagnosis of a hypoplastic left vcntricle that will no1 support the systemic circulation after valvotomy are listed in Table 3. Obviously. other criteria contribute lo such management decisions. including de?endence on prostaglandin E, for systemic blood flow and the failure of the left ventricle to form part of the apex ou two-dimensional echocardiography. When all clinical fcaturcs suggest a hypoplastic left heart and the left ventricular cross-sectional area is : .5 cm’, balloon valvuloplasty would be a reasonable alternative. Infants who continue to show a srxll left ventricle and inability to be weaned from proslaglondin E, or the ventilator. or both. after successful
Lt f Y
IU.1 mm had an angiofrrphic Icfl vcntncular end-diastolic volume of 22X cc/m’. A left venWtlar end-diastolic diameter
area mow
clearly
with ndiameWrof
SKI’WZ
xca
was
explains
the good outcome
IO.1 mm because the
smallest
in the
in
lhis patienl’s
study. This improve this
corrcwion. howvcr. dots not statistically measurcmcnl a5 a predictor of morlahty. rWi!rci/ rnfrc rrnrrfrr.\tfirrw/rr showed considerable overlap berween suwivors and nonsurvivors (Fig. 4). This variable ww nut a predictor of survival. Angiagraphic ventricular w&unes Wig. 51. Lcfl ven!ricular volume dnla were available for review in 17 patients. The mean left ventricular end-diastolic volume index in the surwvor~ (43 ccfm’l was greater than that in lhe nonsurvivort III cc/m”) Lp < O.uOIt. In Ihe group with meutured vohimc~. all of the swwxs had a lctl venuicular cnddiastolic volume index >?O cc/m’ and an ahsolute end-
diastohc
volume
>4.5
had a left ventricular
cc (Fig.
51. Three
of the swvivors
end-diastolic volume index of 20 to
?S cc/m’: no patient wilh a measured index ~20 cc/m’ (n = 5) survivedand an index 120 cc/m’ was a significant predictor of death (p < 0.01). There was no difference in the angqraphically
delermined
ejection
fraction
between
the
groups. There dala arc Gnilar to those previously reported. which included patients 56 momhs of age IQ. Echocardiagrsphic eslimate of left ventricular volume (Fig. 61. In comparing the two-dimensional echocardiographic area meawremcnts and angiographic left ventricular volumes in patienls wth both of these measuretncnts available, a wry good currclalion i% obtained by using the log of the left ventricular end-diastolic volume lr = 0.97). There is also a eood correlalion tr = 0.94) when linear regression is used. A comparison of M-mode left ventricular end.diasw!ic diameler and log of the left ventricular end-diaalolic volume was albo performed. This showed a slightly paorer correlation coefficient of 0.88 and a wdcr scatter. Patients <2 weeks of age. In comparing survivors (n .= 81 and nonwrvivors In = 71 among those patients undergoing vslvotomy before 2 weekr of age (Table 2). the previously
two
&quake fur burvival after valvotomy and who wou!d therefore he candidates for u Norwood procedure or heart transplantation. In 1981. Latxu~ et al. (13) cvaluatcd two echocardiographic criterld for da diagnosis of hppoylaslic left venlr~ule and demonstrated that a measure offeft ventricular cross-sectional area was successful in predicting survival.
Table 3. Uwftil Echocardiographrc Crneria in the Wagno+ Hvpu&rtic Len Ventricle in Critical Ann;c Slenosi?
of
They also apphed this criterion ID five infants with aorlic stcnos~s. hut the miljority of these infants had an enlarged and there ~crc no angiographic lcti ventricular volumes for comparison with the cchocardiographic measuremenls. The present study. This study revealed that the survivors of valvotomy. in addition to having a larger left ventricle. were also older at operalion than the nonsurvivors but did not differ in body weight or sulfaee area. These data are cunsislenl H ilh the premise that the left vcnlricle in six of rhe seve nonsurvivors was not sufficient to support the systemic circulatio,l. Thus. these patients wobld have presented at an earlier age. as soon as ductal constriction became manifest. This study also demonstrates that both an M-mode mcasurcment (left ventricular end-diastolic diameter) and a Iwo-rhmensmnal echocardiographic measurement (left ventricular cross-sectional area! can be used IO estimale left ventricular volume in this group of patients. The latter meaturement is of more value in assessing the size of the left ventricle in this patient group with a steeper curve and less scatter in the region of mosl interesr II .S to 8 cc). especially using logarithmic regression (Fig. 6). In our group of patiems. a left ventricular cross-sectional area ~2 cm2 as measu~-ed on the long-axis echocardiogram successfully identified all four patients with a left ventricular end-diastolic volume index <2il cc/m’ with no false positive or false negative results. One additional patient had a left ventricular cross-seclional area of 1.2 cm’ with no angiographic volume determination and this patient did not survive. Latson et al. (131 measured left ventricular crabssectional area in I9 normal infants aged 5.5 + 5.1 days and weighing 3.1 +_0.4 kg; the mean value was 2.65 cm’ + 2 SD. dclining a normal range of I .S to 3.5 cm’. None of the normal infants had a value <2 cm?. but all infants with a hypoplastic left heart had a YBIW
J
ventricle
because
septal
bowing
from
right
to left leads
to
of left ventricular size. Mitral aqulus size was also smaller in nonsurvivors. but there was considerable overlap of this variable between survivors and nonsurvivors (Table Il. Ludman et al. (22)
significant
found
underestimation
the mitral
anulus
in control
neonates
to average
IO +
3 mm, with one value of1 mm and two of 8 mm. We do not
consider this variable useful unless it is extremely small (56 mm). There are obvious problems with basing treatment up tions on any single measurement such as echocardiographic left ventricular size. This measurement only scrvcs as ancillary supper, for or against surgical valvotomy and should be considered only as a part of the entire clinical presentation. In addition. considerable care should be taken in performing the echocardiogram to ensure that the largest end-diastolic left ventricular image is recorded. Balloon valvuloplasty. The success of balloon valvulm plasry in some investigations (22-26) has made it an attractive alternative technique for selected patients. Zeevi et al. (261 recently compared balloon valvuloplasty with surgical valvotomy in two groups of I6 consecutive infants and found left ventricular size to be a risk factor for early death in both groups. There were eight patients (three surgically treated, five balloon-treated) with a left ventricular end-diastolic volume assessed by angiographic volume measurcmcntn 564% of the predicted value: only one of the eight survived. The survivor had a volume of4l% of the predicted value and was alive al 6 months after two balloon dilations. No follow-up ecbocardiognphic or angiographic data for left ventricular size were available. Clinical and echoeardiographir operative wcee~s. Echocardiographic criteria lhat we consider useful in management decisions regard& the diagnosis of a hypoplastic left vcntricle that will no1 support the systemic circulation after valvotomy are listed in Table 3. Obviously. other criteria contribute lo such management decisions. including de?endence on prostaglandin E, for systemic blood flow and the failure of the left ventricle to form part of the apex ou two-dimensional echocardiography. When all clinical fcaturcs suggest a hypoplastic left heart and the left ventricular cross-sectional area is : .5 cm’, balloon valvuloplasty would be a reasonable alternative. Infants who continue to show a srxll left ventricle and inability to be weaned from proslaglondin E, or the ventilator. or both. after successful