Inrernarional Journal of Cardiology, 29 (1990) 127-139

Elsevier 127

CARD10 01141

Morphometric data concerning the great arterial trunks and their branches

Luis Alvarez, Antonia Aranega, Roberto Saucedo, Jose A. Contreras, Franc&a L6pez

and Amelia Aranega

Department of Morphological Sciences, Basic Cardiovascular Research Seciion, School of Medicine, Unloersify of Granada,

Granada, Spain

(Received 30 March 1990; revision accepted 9 May 1990)

Alvarez L, Aranega A, Saucedo R, Contreras JA, Lopez F, Aranega A. Morphometric data concerning the great arterial trunks and their branches. Int J Cardiol 1990;29:127-139.

In a total of 4% fetuses and newborns ranging in body weight from 60 to 5000 g, we performed a morphometric study of the vasctdar complex, that is the orifices of the great arterial trunks, ascending aorta, aortic arch, vessels branching from the aortic arch, the aortic isthmus, descending aorta, pulmonary trunk, orifices of the pulmonary arteries and arterial duct. In all, 17 different parameters were measured in each specimen, using several new parameters in addition to the measurements classically used in the aortic isthmus, arterial duct and pulmonary trunk. Anatomogeometric models of these structures were developed, and stereometric formulas used to calculate the real volumes of the aortic isthmus, arterial duct and pulmonary trunk. The variations in the correlations between two measurable characteristics, that is, body weight and each of the morphometric parameters were analyzed, and the minimum, normal and maximum patterns of normality for each parameter were obtained with regression equations. The results show that the volume of the aortic isthmus increases by 0.03 ml for each millilitre increase in left ventricular volume. The isthmic volume increases by 0.32 ml for each millilitre increase in volume of the arterial duct and the volume of the pulmonary trunk increases by 6.4 ml for each increase of 1 millilitre in the volume of the aortic isthmus. The inner circumference of the aortic isthmus is greater than that of the arterial duct, whereas the former vessel is always shorter than the latter. We believe that these morphological data, when appropriately interpreted, have immediate clinical and surgical applications in the treatment of fetal and perinatal cardiovascular disorders.

Key words: Human fetal heart; Quantitative anatomy; Vascular complex

Introduction Correspondence to: Prof. Luis Alvarez, Depto. de Ciencias

Morfologicas. Seccibn de Investigaci6n&rsica Cardiovascular,

Facultad de Medicina, Universidad de Granada, Avda. de Madrid s/n, E-18071 Granada, Spain.

With the development of new methods for the prenatal diagnosis of congenital malformations, particularly congenital cardiac malformations, the

0167-5273/90/$03.50 0 1990 Elsevier Science Publishers B.V. (Biomedical Division)

128

last few years have seen a growing interest in data on the quantitative anatomy of the heart and the vascular complex (the ascending aorta, aortic arch,

aortic isthmus, descending aorta, pulmonary trunk, orifices of the pulmonary arteries, arterial duct

and arteries branching from the aortic arch). As put by Anderson [l], “knowledge of the develop-

ment of the heart can be a great aid to under- standing the morphology not only of the normal

heart but of congenitally malformed hearts. How- ever, there is no consensus regarding the events which occur during cardiac development.”

Numerous studies have dealt with this im- portant vascular intersection. Some have been car- ried out in vivo with conventional radiographic

[2], angiographic [3-51 or echocardiographic tech- niques [6-121, while other authors have based their work on autopsy findings [13-191.

Another factor which distinguishes many of

these studies is the age range investigated, some workers limiting themselves to adult hearts [10,19]

and others to fetal material [6,20,21], although the great majority of studies have involved extensive

age ranges. Toda [17], for example, studied speci- mens from 15 weeks of gestation to 90 years of

age. Most studies have only examined certain components of the cardiovascular complex [9- 11,18-20], and very few attempted to present find- ings for all the elements which make up this system [3,22].

Despite the considerable variety of approaches used in these earlier studies, which we have briefly

reviewed above, very few contributions allow us to set appropriate quantitative limits on patterns of

normality for the vascular structures named at the beginning of this introduction. Therefore, we ex- amined the quantitative anatomy of the normal cardiovascular complex in human fetal and peri- natal hearts.

Materials and Methods

The present study, carried out in the Basic Cardiovascular Research Section of the Depart- ment of Morphological Sciences, School of Medi- cine, University of Granada, was based on the analysis of 496 human cardiopulmonary blocks (including the outflow tracts of the great vessels,

TABLE 1

Distribution of weights, in 500 g intervals, of the 496 cases studied.

Body weight (g) No. of

cases

<500 32 501-1000 67

100-1500 91 1501-2000 54 2001-2500 62 2501-3ooO 54 3001-3500 63 3 501-4000 52 400-4500 13 4501-5000 8

ascending aorta, aortic arch, arteries branching from the aortic arch, aortic isthmus, descending aorta, pulmonary trunk, pulmonary branches and

arterial duct) from specimens in the fetal and

perinatal periods of development, ranging in body weight from 60 to 4984 g. Tables 1, 2 and 3

present the distribution of these specimens accord- ing to body weight, age and sex, respectively.

Internal and external anatomical malformations were ruled out in all hearts, which were diagnosed as normal. In no case was the cause of death

related to a congenital cardiac malformation. A set of linear measurements were taken (Fig.

1) in all hearts with a millimeter ruler and com- pass. When a curved surface made it impossible to use these tools, dampened string was lain across

the specimen between the two endpoints and then measured in millimeters.

TABLE 2

Body weight referred to age.

Body weight (g) Age (weeks)

<500 < 26

501-l 000 26-29

1001-l 500 29-33

1501-2000 33-36

200-2500 36-39

2501-3000 39-40 >3000 >40

129

TABLE 3

Postnatal survival in this last group ranged from 1 day to 30

days.

No. cases

Male 283

Female 213

Stillborns Live births

369 127

The following parameters were measured: the inner circumference of the arterial duct at its

origin, near the bifurcation of the pulmonary artery trunk (P,); the internal circumference of the

arterial duct at the point equidistant from its origin and its anastomosis with the aorta ( P2); the

inner circumference of the arterial duct at its anastomosis with the aorta ( P3); the length of the

arterial duct from its origin to its anastomosis with the aorta ( P4); the inner circumference of the

thoracic aorta at a point 1 cm distal to the anas- tomosis of the arterial duct (P,); the inner cir- cumference of the aortic isthmus at a point equidistant from the origin of the left subclavian artery and the anastomosis of the arterial duct with the aorta (P6); length of the aortic isthmus from the origin of the left subclavian artery to the anastomosis of the arterial duct with the aorta (P,); diameter of the orifice of the left subclavian

Fig. 1. Diagram of the linear measurements taken in the

vascular complex in human fetuses ranging in body weight

from 60 to 4984 g.

artery in the aortic arch (P,); diameter of the orifice of the primitive left carotid artery in the aortic arch (P,); diameter of the orifice of the branchiocephalic arterial trunk in the aortic arch

(P,,); inner circumference of the ascending aorta at a point 0.5 cm anterior to the branchiocephalic arterial trunk orifice (P,,); circumference of the

aortic valve (P,2); pulmonary valvar circumfer- ence ( P,3); diameter of the orifice of the right

pulmonary artery ( P14); diameter of the orifice of

the left pulmonary artery (P,,); inner cir- cumference of the pulmonary trunk immediately before its bifurcation (P,,); length of the

pulmonary trunk from its origin at the pulmonary valve to its bifurcation into the right and left pulmonary arteries (P,,).

Volumetric calculations

The volumes of the arterial duct, aortic isthmus and pulmonary trunk were calculated on the basis

of geometric models, as shown in Fig. 2. The suitability of the geometric form employed was previously confirmed in three-dimensional wax models. The arterial duct was assumed to have the shape of two truncated cones joined at their smaller bases, which were considered of equal diameter. The two figures were assumed to have

different heights, such that their corresponding

volumes could be calculated with the following formula:

v AD

= P‘,[P:+2P;+PjZ+(P,.PZ)+(3P.Pz)] 2477

where VA,, is the volume of the arterial duct. Similarly, the aortic isthmus was modeled on a

cylinder, hence its volume was calculated as:

where VA, is the volume of the aortic isthmus.

Finally, the pulmonary trunk was likened to a truncated cone, and its volume was calculated with the following equation:

V PAT = 12n

Fig. 2. Anatomogeometric scheme of the vascular complex.

where VpAT is the volume of the pulmonary trunk. After obtaining the values for all 17 parameters

in a sample of 496 fetal and perinatal hearts, we analyzed the correlation in search of joint varia- tions between two measurable characteristics, i.e., body weight and each of the parameters. No inter- vals were used in any of the parameters, rather,

each value was recorded exactly as measured. The table of normal values was prepared on the

basis of three different regression equations: the normal regression, and the maximum and mini-

mum regression, which determined the confidence limits of the corresponding regression lines. We should note that maximum and minimum correla- tions were calculated from the highest and lowest values for body weight within each 100 g interval.

Having obtained the patterns of normality for all 17 parameters, the formulas given above were used to calculate the normal, maximum and minimum volumes of the arterial duct, aortic

isthmus and pulmonary trunk for each 100 g inter- val of body weight.

Results

After taking the 17 linear measurements de- scribed above in all 496 cardiopulmonary blocks,

appropriate statistical analyses were used to ob- tain the intervals of normality for each parameter.

These values were used to calculate the intervals of normality for the volume of the arterial duct, aortic isthmus and pulmonary trunk. Rather than going into a lengthy and somewhat dry list of figures, it seemed to us more informative to pre-

sent separately our findings in each segment of the vascular complex, eventually to summarize the correlations between those parameters we consider

most important.

On measuring the inner circumference of the aortic isthmus halfway between the origin of the

left subclavian artery and the anastomosis of the

arterial duct with the aorta ( P6), we found mean normal values to range from 0.846 cm to 1.374 cm in specimens weighing from 101 to 5000 g, respec-

tively. As shown in Fig. 3, there was a statistically significant correlation (P < 0.0001) between fetal weight in kg and the inner circumference of the

aortic isthmus at this point. The regression equa- tion demonstrated that the inner circumference

increased an average of 0.17 cm per kg increase in body weight. The mean normal intervals for the length of the aortic isthmus, that is, the distance from the origin of the left subclavian artery to the anastomosis of the arterial duct with the aorta (PI,), ranged from 0.598 to 0.772 cm in fetuses weighing 101 to 5000 g. Fig. 4 illustrates the discrete but nonetheless significant correlation (P < 0.0001) between fetal weight in kg and the distance from the origin of the left subclavian

artery to the anastomosis of the arterial duct with the aorta (P,). This parameter showed an average increase of 0.06 cm per kg increase in body weight. Mean normal values for volume of the aortic isthmus, calculated on the basis of the cylindrical model described above, ranged from 0.034 to 0.115 ml in fetuses weighing 101 to 5000 g. The good statistical correlation between the volume of the aortic isthmus and body weight (P < 0.0001) is

131

cm

2

15

I

0.5

i:

r = 0 829

p<o 0001

P6

0

0 0

.c. o...o. .O 0

. 0.0.00... .O

000.0 . . . . . . . . . . . 0

0 0 . . . . . . . . . . . . . . . 00

..o . . . . . . 0. . . . . . . 00 00.

cJ0...........00.00 0 00

. . . . . . . . . . . 0

. . . . . . . 0 0. 0

. . . . . 0

. . 0

“0 y = 0.5688b + 0. f70481, x

1 , 2 3 4 5

WE/G/f7 (kg I

Fig. 3. Regression plots of the inner circumference of the aortic

isthmus at a point halfway between the origin of the left

subclavian artery and the anastomosis of the arterial duct

against the aorta (P,) and body weight in kg. o, one case; 0, more than one case.

0 25

p7

r=o550

P<O 0001

‘

f 2 3 4 5

WEIGHT I kg I

Fig. 4. Regression plots of the length of the aortic isthmus

from the origin of the left subclavian artery to the anastomosis

of the arterial duct with the aorta (P,) against body weight in

kg. o, one case; 0, more than one case.

r = 0778

p<oooO/

y= 4.9105991 + 0.014841 x

0 .

00 00000

. 0 00 000. . 00

0. o....o

. 0 . . . . . 0 . . . . .O

0 0 ..o..o...o.. 000

. . . . . . . . . . . . . . . . 0 0

. . . . . . . . . . . . . . . 0.0. 0 0

0 . . . . . . . . . . . . 0.. 00 . .

. . . . . . . 000. 0

WEIGHT (kg I

Fig. 5. Regression plots of the volume of the aortic isthmus

(AIV) and body weight in kg. o, one case: 0, more than one

case.

illustrated in Fig. 5, the former increasing an average of 0.01 ml per kg increase in fetal body

weight. We also calculated the correlations between

volume of the aortic isthmus and the volumes of

the left ventricle, arterial duct and pulmonary trunk. The correlation between the volumes of the aortic isthmus and the left ventricle was statisti-

cally significant (P < O.OOOl), as shown in Fig. 6.

The volumes of the aortic isthmus increased an average of 0.03 ml per ml increase in left ventricu-

lar volume. Fig. 7 illustrates the significant corre- lation between the volumes of the isthmus and the arterial duct (P < 0.0001). the former rising an average of 0.32 ml per ml increase in the latter. A similar degree of correlation was found between the volume of the isthmus and that of the

pulmonary trunk (Fig. 8) (P < O.OOOl), the latter showing an average rise of 0.64 ml per ml increase in volume of the aortic isthmus.

Another parameter which provides much useful information is the inner circumferences of the thoracic or descending aorta at a point 1 cm distal

132

I = 0 792

P <OOOOf

y = - I. 2154064 + 0.02636 x

0 .

00..

DO 0 O..D.OO

0 . . ..O

00 . . . . . . . 0

0 DO.O..... .

. . . . . . . . . . . 0

0.0 . . . . . . . . . . . 0..0

0. . . . . . . . . . . . . . . .

. . . . . . . . . . . . 0.0 a

‘“V ml

Fig. 6. Regression plots of the volume of the aortic isthmus

(AIV) against left ventricular volume (LVV). 0, one case; 0, more than one case.

A IV ml

Fig. 8. Regression plots of the volume of the aortic isthmus

(AIV) and that of the pulmonary trunk (ITV). O. one case; 0,

more than one case.

, = 0.747

P <ocOo1

00 0 .0.00 0

.x0.0.... 0

0.0 . . . . . . . 0

0 . . . . . . . . . .

. . . . . . . . . 000 0

l . . . . . . . . 0 0

. . . . . . . . 0

. . . . 0 y - 0.0159479 + 0.3f6t-2. x

1

0.5

r = 0.804

P <o 0001

0

0 00 0

0 00 00

0 00 0 0

. . . . . .

00.0.. . 0

o...a....

0 00 . . . . 0 0

0 . . . . . .OO .

. . . . . . . a0 . 0

. . . . . .

, o...... 0.30

. . . . . . .

. . . . . . . . 0

b.....O y -0 0133424 + 6.36982 x

I....

.2

I * 0.880

p<o.oooi

. 0.

0 0 0 00‘3 oc

0 . . . . . . . . . ..o.

00 .O..........O.O”

00. l . . . . . . . . . . ..o. 0

. . . . . . . . . . ..o 00

0.. . . . . . . . 0 0

D . . . . . . . 00

. . . . ..O

3...0

. . y = 0.753/95 + 0.249842 *

0

_ I 2 3 4 5

WEIGHT (kg)

0 AV ml

Fig. 7. Regression plots of the volume of the aortic isthmus

volume (AN) and that of the arterial duct (DAV). 0, one case; 0. more than one case.

Fig. 9. Regression plots of the inner circumference of the

descending aorta at a point 1 cm distal to the anastomosis of

the arterial duct (P,) against body weight in kg. 0, one case; l , more than one case.

133

I - 0 650

P<0.000f

pi2

0

0 00

0 0 .00 0

0 0 ..O . . . . . 0...00 00

00.0 . . . . . 0..000

00 0 . . . . . . . . . . 0 0

. . . . . . . . . . 0.0 0 0

0 . . . . . . . . . . . . . 0.

0. . . . . . . . . 0

. . . . ..o 0

. . . . . . 0

c,.. .

. . .

y = 0.949/i7 t 0 267235. x

- I 2 3 4 5

WEIGHT (kg I

Fig. 10. Regression plots of the circumference of the aortic

valve (P,,) against body weight in kg. 0, one case; 0, more

than one case.

93 cm

3

2.4

i.8

I.2

0.6

c

r = 0852

p<o.oooi D

0 0

0

DO 0 . 0.0 0.00. 00 0

0.. .O . . . . 0..0 oc

0 0 . . . . . . . . . . . . . ..O

O...O.O...U..Q. 00.

000 . . . . . . . . . . . . . . . 0.

0 0.0 . . . . . . 0 0..0

. . . . l . . . . 0.. 0 0

0 . . . . . . . . D .

0...... 0

0 . . . . 0

.0. D

. ..00 y = O 936259 + 0 32034E a

WEIGHT / kg I

Fig. 11. Regression plots of pulmonary valvar circumference

(P,,) against body weight in kg. o, one case; 0, more than one

case.

Pf2IcmI

Fig. 12. Regression plots of pulmonary valvar circumference

( P13) against aortic valvar circumference ( PI, ). 0. one case; 0,

more than one case.

D

r = 0942 0 0

0

P<O.cOOf . 0

. . . . .

. . ...00

. . . . . . 0

. . ...000

.O . . . .

. . ..O

. . . . . .

0.....000

. . . . .

0....0

. .

..O

0 Y * 00925550 + / f2650 x

to the anastomosis of the arterial duct ( P5). The intervals of normality for this parameter ranged from 1.078 cm in fetuses weighing 101 g to 1.854

cm in specimens weighing 5000 g. Fig. 9 shows the

clearly significant correlation (P < 0.0001) be- tween fetal body weight and the inner cir-

cumference of the thoracic or descending aorta at a point 1 cm distal to the anastomosis of the

arterial duct (P,), and the corresponding regres- sion equation further showed that the inner cir- cumference of the thoracic aorta increased an

average of 0.25 cm per kg increase in body weight. The circumference of the aortic orifice at the

level of the leaflets of the aortic valve (P,?) was positively correlated (P -C 0.0001) with fetal body weight (Fig. lo), and the regression equation showed that the circumference at the level of the aortic valve ( P,2) increased an average of 0.27 cm per kg increase in fetal weight. Pulmonary valvar circumference ( P13) was also significantly corre- lated with fetal weight (P < 0.0001) (Fig. 11). The corresponding regression equation demonstrated an average increase in pulmonary valvar cir-

cumference (P,,) of 0.32 cm per kg rise in body

134

weight (Fig. 12). Aortic valvar circumference (I’,*) was also found to be significantly correlated with the circumference of the pulmonary valve (I’,,), as

shown in Fig. 12. The latter parameter showed an average increase of 1.13 cm per cm increase in the

former.

Discussion

Few studies to date have dealt with the quanti- tative anatomy during the fetal and perinatal

period in the vascular complex (orifices of the great arteries, ascending aorta, aortic arch and its branches, aortic isthmus, descending aorta, arterial duct, pulmonary trunk and orifices of the

pulmonary arteries) (Figs. 1 and 2). Van Meurs- Van Woezik et al. [13] studied 46 human hearts: 35 from fetuses weighing 4700 g or less, and 11 from subjects 6 to 36 kg, with ages ranging from

25 weeks’ gestation to 9 years. Using calibrated probes, these authors measured the diameters of

the aortic and pulmonary orifices, aortic isthmus

and descending aorta, and noted correlations be- tween these parameters and body length. The smail

sample size, together with the wide range of body weights and ages considered, make their data somewhat unreliable as a basis for establishing definitive intervals of normality. Likewise the use

of calibrated probes seems questionable, since these instruments can distend the vessels. String, by contrast, can be precisely adjusted to the curved or irregular inner surfaces of the vessel being measured once the lumen has been exposed with

scissors. This can then be transferred to a millime- ter scale, a technique which offers greater accu- racy.

Van Meurs-Van Woezik et al. [13] did not obtain patterns of normality for the parameters actually measured, as the diameter of the aortic isthmus, for example, was found to be 4 mm in different fetuses weighing 1080, 1450, 1950, 3050 and 3300 g. A similar situation presented itself in the diameters of the aortic and pulmonary orifices and the descending aorta. Our data for patterns of normality suggest that each parameter increases at a steady rate in relation to rising body weight. We, therefore, disagree with the values in the tables of Van Meurs-Van Woezik and her colleagues [13]

for these parameters. Although we agree that the pulmonary arterial orifice is larger than that of the aorta, this difference becomes obvious only in

fetuses of 2000 g body weight and over, and is not systematically evident in all phases of develop-

ment.

Based on their data for the aortic isthmus, Clarkson et al. [3] explain the presence or absence

of narrowing as evidenced by the index derived

from the area of the cross-section through its narrowest point. divided by the area of the cross section of the descending aorta through a point immediately distal to the arterial duct. If the re- sulting index is less than 0.81, a narrowing is said

to exist, whereas a figure equal to or greater than 0.81 proves the absence of narrowing. In the light of our observations, there appears to be no nar- rowing of the isthmus. Under normal cir- cumstances (Fig. 3) the inner circumference at the midpoint of the isthmus increases 0.17 cm per kg increase in fetal body weight. Clarkson et al. [3]

correlated their measurements with body length, a

parameter we consider of doubtful value. Like

Rakusan et al. [23], we found that increases in heart weight, and hence in heart size, were propor- tional to increases in body weight rather than body length. Thus, body weight is a more signifi-

cant determinant of heart growth in the course of development, an opinion shared by St. John Sut- ton et al. [25]. Our findings furthermore show a statistically significant correlation (P -c 0.0001) between these parameters and fetal body weight in kilograms.

We agree with Yousefzadeh et al. [2] in that the inner circumference of the descending aorta at a

point 1 cm distal to the anastomosis of the arterial duct is consistently larger than the inner cir- cumference of the aortic isthmus at its midpoint.

This feature, in radiological studies, can produce a picture similar to that seen in aortic coarctation and may, hence, give the misleading impression of a pathological aortic isthmus. Clarkson et al. [3] claimed that the aortic isthmus in 90% of all 3-month-old infants is of the same caliber as the descending aorta, whereas the former is much smaller in newborns due to the smaller volume of blood flowing through the isthmus during the fetal period. Our data in this regard are not compara-

135

ble, as none of our 496 cases was older than 1

month. The length of the aortic isthmus, that is, the

distance between the origin of the left subclavian artery and the anastomosis of the arterial duct with the aorta (Figs. 1, 2 and 4). has not been

previously measured. These measurements, to- gether with the data on the inner circumference of

the isthmus, suggest that this segment should be modeled on a cylinder rather than on a truncated

cone, as was used by Domenech and Puerta [18] in order to calculate its volume and to compare it

with the volumes of other vascular and cardiac

structures (Figs. 5, 6, 7 and 8). Allan et al. [7] studied fetal heart anatomy with

cross-sectional echocardiography. and described a

set of planes which could be used to establish normal anatomical patterns. These authors called

attention to the need for a more solid knowledge of fetal cardiac anatomy and mechanics based on anatomical studies, and underlined the usefulness

of applying such information to clinical explora- tory techniques. Likewise, Lapasset et al. [6] have drawn attention to the importance of quantitative data on fetal cardiovascular structures.

Angelini et al. [26] studied the hearts and great vessels of 30 human fetuses ranging in gestational

age from 10 to 30 weeks, after excluding cardio- vascular anomalies. These authors separated the

great vessels from the heart and lungs, and calcu- lated the relationship between the diameter of

each vessel and that of the ascending aorta, which was chosen as a “control”. They then compared

these postmortem morphometric data with echo- cardiographic data obtained from fetuses ranging

in gestational age from 23 to 27 weeks, in 20 women. All fetuses were healthy at delivery and

thereafter. The ascending aorta was constant in diameter, and was thus chosen for purposes of comparison. The postmortem data gave a ratio between the isthmus and the ascending aorta of 0.63 (O.ll), while the ratio between the arterial duct and the ascending aorta was 0.51 (0.13). The isthmus was larger than the duct in 20 of 30 cases, smaller in seven of 30, and the same size in three specimens. The duct was 38.26% smaller in diame- ter than the descending aorta, while the isthmus was found to be 24.57% smaller in diameter. The

echocardiographic data showed the isthmus to be larger in diameter than the duct in 15 cases, the same size in three and smaller in only two cases. The ratio between the isthmus and the ascending aorta was 0.73 (0.07). while that between the

arterial duct and the ascending aorta was 0.7 (0.08). Thus, the observations of Angelini et al.

[26] in human midterm fetuses, show that the isthmus is always wider than the duct. We concur

with these authors, on the basis of our patterns of normality for intervals of 100 g body weight

throughout the entire fetal period for the follow-

ing parameters: the inner circumference of the

arterial duct at its origin near the bifurcation of

the pulmonary trunk ( P4) (Table 4); the inner

circumference of the arterial duct at the point

equidistant from its origin and its anastomosis with the aorta (P,) (Table 5); the inner cir-

cumference of the arterial duct at its anastomosis

with the aorta ( P3) (Table 6); and the inner cir- cumference of the aortic isthmus at a point equidistant from the origin of the left subclavian artery and the anastomosis of the arterial duct

(P,) (Table 7). As these tables show. the differences are quite

large. and indicate that the aortic isthmus in the human fetus is always wider than the duct. With

regard to the pulmonary arteries, Angelini et al.

[26] noted in their postmortem studies that the right pulmonary artery was larger than the arterial

duct in 16 cases, equal to the duct in six and smaller in eight of the 30 hearts measured. The left

pulmonary artery was always smaller than the right. Our postmortem observations of 496 hearts showed that the right pulmonary artery was larger

than the arterial duct throughout fetal develop-

ment from 101 to 5000 g body weight. while the left pulmonary artery was always smaller than the right during the entire period of development just mentioned. Thus, our data again concur with the findings of Angelini et al. [36].

On the other hand, these findings differ from those of Rudolph et al. [27.28]. who concluded. on the basis of measurements taken in fetal lamb hearts. that the arterial duct was wider than the aortic isthmus. Such data. therefore. may not be applicable to human fetuses. In recent studirh. these authors state “that the ascending ;mrta.

136 .

TABLE 4 TABLE 5

Patterns of normality for the inner circumference of the arterial duct at its origin near the bifurcation of the pulmonary trunk in 496 normal human fetuses (I’,). Minimum, mean and maxi- mum values in centimeters.

Patterns of normality for the internal circumference of the arterial duct at a point halfway between its origin and its anastomosis with the aorta ( P2) in 496 normal human fetuses. Minimum, mean and maximum values in centimeters.

Body weight (g) Minimum Mean Maximum

lOl- 2c4l 0.348 0.506 0.662 101- 200 ZOl- 300 0.500 0.620 0.742 201- 300 301- 400 0.588 0.692 0.798 301- 400 401- 500 0.650 0.746 0.840 401- 500 501- 600 0.697 0.786 0.876 501- 600 601- 700 0.736 0.822 0.906 601- 700 701- 800 0.770 0.852 0.932 701- 800 801- 900 0.798 0.878 0.956 801- 900 901-l WO 0.824 0.900 0.976 901-1000

100-l 100 0.848 0.920 0.994 100-l 100

1101-1200 0.868 0.940 1.012 1101-1200

1201-1300 0.886 0.956 1.028 1201-l 300

1301-1400 0.904 0.972 1.042 1301-l 400

140-1500 0.920 0.988 1.056 140-1500 1501-1600 0.934 1.002 1.068 1501-l 600 1601-1700 0.948 1.014 1.080 1601-1700

1701-l 800 0.962 1.026 1.092 1701-l 800

1801-1900 0.974 1.038 1.102 1801-1900

1901-2000 0.986 1.048 1.112 1901-2000

200-2100 0.996 1.060 1.122 2001-2100

2101-2200 1.008 1.068 1.130 2101-2200

2201-2300 1.018 1.076 1.140 2201-2300

2301-2400 1.026 1.088 1.148 2301-2400

2401-2500 1.036 1.096 1.156 2401-2500

2501-2600 1.044 1.104 1.164 2501-2600

2601-2700 1.054 1.112 1.170 2601-2700

2701-2800 1.062 1.120 1.178 2 701-2 800

2801-2900 1.070 1.126 1.184 2801-2900

290%3ooO 1.076 1.134 1.192 2901-3000

300-3 100 1.084 1.140 1.198 3001-3100

3 101-3200 1.092 1.148 1.204 3 101-3200

3201-3300 1.098 1.154 1.210 3201-3300

3301-3400 1.104 1.160 1.216 3301-3400

340-3500 1.110 1.166 1.222 340-3500

3501-3600 1.118 1.172 1.228 3501-3600

3601-3700 1.124 1.178 1.232 3601-3700

3701-3800 1.130 1.184 1.238 3701-3800

3801-3900 1.134 1.188 1.242 3801-3900

3901-4000 1.140 1.194 1.248 3901-4000

400-4100 1.146 1.200 1.252 4001-4100 4101-4200 1.152 1.204 1.258 4101-4200

4201-4300 1.156 1.210 1.262 4201-4300

4301-4400 1.162 1.214 1.266 4301-4400

4401-4500 1.166 1.218 1.270 4401-4500

4501-4600 1.172 1.224 1.276 4501-4600 4601-4700 1.176 1.228 1.280 4601-4700 4 701-4 800 1.180 1.232 1.284 4701-4800 4801-4900 1.186 1.236 1.288 4801-4900 4901-5000 1.190 1.240 1.292 4901-5000

Body weight (g) Minimum -

0.336

Mean

0.478

Maximum

0.620

0.686 0.732

0.768 0.798 0.824 0.846 0.864 0.882 0.896 0.912 0.924 0.936 0.948 0.958 0.968 0.978 0.986

0.994 1.002 1.010

1.018 1.024 1.030 1.038 1.044 1.050 1.054 1.060 1.066 1.070 1.076

1.080 1.086 1.090 1.094 1.100 1.104 1.108 1.112 1.116 1.120 1.124 1.126 1.130 1.134 1.138 1.140 1.144

0.464 0.574

0.538 0.636 0.590 0.680 0.630 0.714 0.664 0.744 0.692 0.768 0.716 0.790 0.738 0.810 0.756 0.826 0.774 0.842 0.790 0.858 0.804 0.870 0.818 0.882 0.830 0.894 0.842 0.906 0.854 0.916

0.864 0.924 0.874 0.934 0.884 0.942 0.892 0.950 0.900 0.958 0.908 0.966 0.916 0.974 0.924 0.980 0.930 0.988 0.938 0.994 0.944 1.000 0.950 1.006 0.956 1.012 0.962 1.016 0.968 1.022 0.974 1.028 0.980 1.034 0.984 1.038 0.990 1.042 0.994 1.048 1.000 1.056 1.004 1.056 1.010 1.060 1.014 1.064 1.018 1.068 1.022 1.072 1.026 1.076 1.030 1.080 1.034 1.084 1.038 1.088 1.042 1.092 1.046 1.094

TABLE 6 TABLE 7

Patterns of normality for the inner circumference of the arterial duct at its anastomosis with the aorta (F’s) in 496 normal human fetuses. Minimum, mean and maximum values in

centimeters.

Patterns of normality for the inner circumference of the aortic isthmus at a point halfway from the origin of the left sub- clavian artery and the anastomosis of the arterial duct (P6) in 496 normal human fetuses. Minimum. mean and maximum values in centimeters.

Body weight (g) Minimum Mean Maximum

IOI- 200 0.250 0.408 0.566 201- 300 0.398 0.520 0.642 301- 400 0.484 0.590 0.696 401- 500 0.544 0.642 0.738 501- 600 0.592 0.682 0.774 601- 700 0.630 0.716 0.802 701- 800 0.662 0.746 0.828 801- 900 0.690 0.770 0.850 901-l 000 0.716 0.792 0.870

1001-l 100 0.738 0.814 0.888 1101-l 200 0.758 0.832 0.906 1201-1300 0.776 0.848 0.920 1301-1400 0.792 0.864 0.934 1401-1500 0.808 0.878 0.948 1501-1600 0.824 0.892 0.960 1601-1700 0.836 0.904 0.972 1701-l 800 0.850 0.916 0.982 1801-1900 0.862 0.928 0.992 1901-2000 0.874 0.938 1.002 200-2 100 0.884 0.948 1.012 2101-2200 0.894 0.958 1.020 2201-2300 0.904 0.966 1.030 2301-2400 0.914 0.976 1.038 2401-2500 0.922 0.984 1.046 2501-2600 0.930 0.992 1.052 2601-2700 0.940 1.000 1.060 2701-2800 0.948 1.006 1.066 2801-2900 0.954 1.014 1.074 2901-3000 0.962 1.020 1.080 3001-3100 0.970 1.028 1.086 3101-3200 0.976 1.034 1.096 3201-3300 0.982 1.040 1.099 3301-3400 0.990 I .046 1.104 340-3500 0.996 1.052 1.110 3501-3600 1.002 1.058 1.114 3601-3700 1.008 1.064 1.120 3701-3800 1.014 1.070 1.124 3801-3900 1.020 1.074 1.130 390-4000 1.024 1.080 1.134 4001-4100 1.030 1.084 1.140 4101-4200 1.034 1.090 1.144 4201-4300 1.040 1.094 1.148 4300-4400 1.044 1.100 1.154 440-4500 1.054 1.104 1.158 4501-4600 1.058 1.108 1.162 4601-4700 1.060 1.112 1.166 4701-4800 1.064 1.116 1.170 4801-4900 1.068 1.120 1.174 4901-5000 1.072 1.124 1.178

137

Body weight (g) Minimum Mean Maximum

lOl- 200 0.730 0.846 0.960 201- 300 0.838 0.928 1.018 301- 400 0.902 0.980 1.058 4O- 500 0.946 1.018 1.090 501- 600 0.982 1.048 1.114 601- 700 1.010 1.072 1.136 701- 800 1.034 1.094 1.154

801- 900 1.054 1.112 1.172 90-1000 1.072 1.130 1.186

100-1100 1.090 1.144 1.200 1101-l 200 1.104 1.158 1.212 1201-1300 1.118 1.170 1.224 1301-1400 1.130 1.182 1.234 140-1500 1.142 1.192 1.244 1501-1600 1.152 1.202 1.252 1601-1700 1.162 1.212 7.260 1701-1800 1.172 1.220 1.268 1801-1900 1.180 1.228 1.276 1901-2000 1.190 1.236 1.284 2001-2100 1.196 1.244 1.290 2101-2200 1.204 1.250 1.298 2201-2300 1.212 1.258 1.304 2301-2400 1.218 1.264 1.310 240-2500 1.226 1.270 1.316 2501-2600 1.232 1.276 1.320 2601-2700 1.238 1.282 1.326 2701-2800 1.244 1.288 1.330 2801-2900 1.250 1.292 1.336 2901-3000 1.254 1.298 1.340 3001-3100 1.260 1.302 1.342 3101-3200 1.266 1.308 1.350 3201-3300 1.270 1.312 1.354 3301-3400 1.274 1.316 1.358 3401-3500 1.280 1.320 1.362 3501-3600 1.284 1.326 1.366 3601-3700 1.288 1.330 1.370 3701-3800 1.292 1.334 1.374 3801-3900 1.296 1.338 1.378 3901-4000 1.300 1.340 1.382 400-4100 1.304 1.344 1.384 4101-4200 1.308 1.348 1.388 4201-4300 1.312 1.352 1.392 4301-4400 1.316 1.356 1.394 4401-4500 1.320 1.358 1.398 4501-4600 1.322 1.362 1.400 4601-4700 1.326 1.366 1.404 4701-4800 1.330 1.368 1.408 4801-4900 1.332 1.372 1.410 4901-5000 1.336 1.374 1.412

138

which carries 35-40% of the combined ventricular output, is similar in diameter to the descending

aorta, which is presumed to carry about 70% of the combined ventricular output.” We found that,

in human fetuses, the inner circumference of the ascending aorta at a point 0.5 cm anterior to the branchiocephalic arterial trunk orifice (P,,) was consistently larger than the inner circumference of

the thoracic (descending) aorta at a point 1 cm distal to the anastomosis of the arterial duct (P,) throughout fetal development. The inner cir-

cumference of the ascending aorta at a point 0.5 cm anterior to the branchiocephalic arterial trunk

orifice measured 1.136 cm in fetuses ranging in

body weight from 101-200 g, and 1.916 cm in

fetuses weighing 4901-5000 g, while the inner circumference of the descending aorta at a point 1

cm distal to the anastomosis of the arterial duct was 1.078 cm in fetuses weighing 101-200 g in

body weight, and 1.854 cm in fetuses of 2901-5000

g in body weight. We believe that data from animal models, such

as the fetal lamb, should be used with caution when attempting to extrapolate such findings to

human material. The concepts and methods described in the

present study, although they will need to be corre-

lated with data obtained with echocardiographic studies, have immediate clinical and surgical ap- plications, as well as opening new avenues to

morphological and functional research.

Acknowledgement

We thank Ms. Karen Shashok for translating the original manuscript into English.

References

Anderson RH, Becker AE. Cardiac anatomy. An integrated

text and colour atlas. London: Gower Medical Publishing,

1980;10.2-10.3.

Yousefzadeh DK, Chow KC, Franken EA. The aortic

isthmus. Radiology 1981;140:710-703. Clarkson P, Brandt PWT. Aortic diameters in infant and

young children: normative angiographic data. Pediat

Cardiol 1985;6:3-6.

Sievers H, Onmasch DGW, Lange PE, Bernhard A, Heint-

zen PH. Dimensions of the great arteries, semilunar valve

roots, and right ventricular outflow tract during growth:

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

normative angiocardiographic data. Pediat Cardiol 1983;4:

189-196.

Santos MA, Moll JN, Drummond C, Araujo WB, Romao

N, Reis NB. Development of the ductus arteriosus in right

ventricular outflow tract obstruction. Circulation 1980;62:818-822.

Lapasset M, De Geeter B, Renalud R. Echographic

quantitative du coeur foetal. Arch Ma1 Coeur 1985;5:627-

631.

Allan LD, Tynan MJ, Campbell S, Wilkinson JL, Anderson

RH. Echocardiographic and anatomical correlates in the

fetus. Br Heart J 1980;44:44-451.

Snider AR, Enderlein MA, Teitel DF, Juster RP. Two

dimensional echocardiographic determination of aortic and

pulmonary artery sizes from infancy to adulthood in nor-

mal subjects. Am J Cardiol 1984:53:218-224.

Epstein ML, Goldberg SJ, Allen HD, Konecke L. Wood J.

Great vessel, cardiac chamber, and wall growth patterns in

normal children. Circulation 1975;51:1124-1129.

Francis GS, Hagan AD, Oury J, O’Rourke RA. Accuracy

of echocardiography for assessing aortic root diameter. Br

Heart J 1974;37:376-378.

Nanda NC. Echocardiography of the aortic root. Am J

Med 1977;62:836-842.

Walter LH, Gardin JM, Ware J. Echocardiographic mea-

surements in normal subjects from infancy to old age.

Circulation 1980;62:1054-1061.

Van Meurs-Van Woezik H, Klein HW, Krediet P. Normal

internal calibres of ostia of great arteries and of aortic

isthmus in infants and children. Br Heart J 1977;39:86-865.

Van Meurs-Van Woezik H, Klein HW. Calibres of aorta

and pulmonary artery in hypoplastic left and right heart

syndromes: effects of abnormal blood flow? Virchows Arch

A 1974;364:357-364.

Van Meurs-Van Woezik H, Krediet P. Measurements of the

descending aorta in infants and children: Comparison with

other aortic dimensions. J Anat 1982;135:273-279.

Van Meurs-Van Woezik H. Krediet P. Changes after birth

in the tunica media and in internal diameter of the aortic

isthmus in normal newborns. J Anat 1982;134:573-581.

Toda T, Tsuda N, Takagi T, Nishimori I, Leszczynski D.

Kummerow F. Ultrastructure of developing human ductus

arteriosus. J Anat 1980:131:25-37.

Domenech JM, Puerta J. La region de1 istmo abrtica en el

period0 fetal. Rev Esp Cardiol 1976;29:173-178.

Wright NL. Dissection study and mensuration of the hu-

man aortic arch. J Anat 1969;104:377-385.

DeVore G, Sialli B, Platt L. M-mode measurements of the aortic root and aortic valve in second- and third-trimester normal human fetuses. Am J Obstet Gynecol 1985;July 1:543-550.

Shime J, Gresser RN, Rakowski H. Quantitative two-di-

mensional echocardiographic assessment of fetal cardiac

growth. Am J Obstet Gynecol 1986;154:294-300.

Heyman MA, Rudolph AM. Control of the ductus arterio-

sus. Physiol Rev 1975;55:62.

Rakusan K, Jelinek J, Korecky B, Soukupora M, Poupa 0. Postnatal development of muscle fibers and capillaries in

the rat heart. Physiol Bohemoslov 1965;14:32-37.

139

24 Long WA, Tooleg W. McNamara D. Fetal and neonatal

cardiology. London: WB Saunders. Harcourt Brace

Jovanovich, 1990;3-16.

25 St John Sutton MG. Gweitz MH, Shah B, et al. Quantita-

tive assessment of growth and function of the cardiac

chambers in the normal human fetus: a prospective longitu-

dinal echocardiographic study. Circulation 1984:69:645-

654.

26 Angelini A. Allan LD. Anderson RH. Crawford DC, Chita

DK. Yen Ho S. Measurements of the dimensions of the

aortic and pulmonary pathways in the human fetus: a

correlative echocardiographic and morphometric study. Br

Heart J 1988;60:221-226.

27 Rudolph AM. Heyman MA. Teramo KAW. Barret CT,

Raiha NCR. Studies on the circulation of the prviable

human fetus. Pediatr Res 1971:5:452-465.

28 Rudolph AM. Heyman MA. Spitnas U. Hemodynamic

considerations in the development of the narrowing of the

aorta. Am J Cardiol 1972;30:514-525.

29 Rudolph AM. Distribution and regulation of blood flow in

the fetal and neonatal lamb. Circulation 1985:57:811-X21.