Acta Obstet Gynecol Scand 55: 101-104, 1976
DISTRIBUTION OF BLOOD FLOW IN MYOMATOUS UTERI AS MEASURED BY LOCALLY INJECTED '33XENON Lars Forssman Department of Obstetrics and Gynecology (Head Prof. P . Bergman), Ostra sjukhuset, Gothenburg, Sweden
Abstract. Regional blood flow in the myometrium and myomata has been measured during laparotomy in I 1 pa-
tients using locally injected '33Xenon. Blood flow was calculated from the wash-out curves using both initial slope technique and compartment analysis. Assuming equal partition coefficients in myometrium and myomata the following values in ml smin-1. 100 g-1 are seen: initial slope technique-myometrium 15.6f2.29, myomata 5.1 f0.95, compartment analysis-myometrium 20.01f3.21, myomata 5.5f1.16. The blood flow was always lower in myomata than in myometrium of the same uterus. The main reason for the reduction of blood flow per unit weight of uterus in patients with myomata previously reported thus seems to be low blood flow in the myomata. A slight reduction of blood flow in the surrounding myometrium, however, also seems probable.
observations cited above (7, 10) may depend on a generalized slowing of blood flow in the myomatous uterus as a whole, blood flow in myomata and the surrounding myometrium being of about the same magnitude. They may also be the result of a very low blood flow in myomata and only a slight or no reduction in the perfusion of the surrounding myometrium. Previous studies d o not give any information o n blood flow within myomata as compared with normal myometrium in the same uterus. The present work was intended t o compare within the same uterus and a t the same occasion blood flow in myomata and in the intervening myometrium.
In a previous study (7) using the isotope clearance method, it was shown that blood flow per unit weight of myomatous uterus is reduced in compari-
METHODS A N D MATERIAL The isotope clearance method utilising '"Xenon
is in agreement with this idea. Degenerative changes in uterine myomata are frequent and are thought to reflect insufficient blood supply. However, morphological data indicate great variations in vascularity in myomata (3.4, 8, 13). Furthermore the blood vessels of the surrounding myometrium are affected by the myomata. This effect was described by Sampson (14) and in a more recent study by Farrer-Brown et at. (2). By compressing veins myomata may impair drainage of the surrounding myometrium and endometrium. This effect may lead to pathological uterine bleeding. It may also lead to a reduction in blood flow in normal myometrium surrounding myomata. Thus the
solution was injected via the uterine serosa. In a few cases a smaller volume was used-identical volumes injected into both myomata and myometrium. In myomata the injection depth varied with the size of the tumor, but in all cases the isotope was deposited well inside the capsule of the myoma. The injections into normal myometrium were made at a depth of 0.5 to 0.7 cm from the serosa. The needle was as a rule held obliquely to the surface to ensure a needle track of at least 0.7 to 1 cm. The injection needle had an outer diameter of 0.4 mm. No aspiration was made prior to isotope injection. Injection time was 20 sec and the needle was left in situ for another 20 sec in order to minimize the risk of leakage through the needle track. Recording was carried out as described for intraarterial injections (5). In all cases at least two recordings were carried out. Since remaining isotope from previous injections might interfere with following recordings, old
was
Acta Obstet Gynecol Scand 55 (1976)
102
Lars Forssman
isotope depots were shielded with lead so that they were not seen by the detector. Two types of curve analysis were performed. The initial slope method for curve analysis was applied on all curves using the initial portion of the curve but disregarding any steep fall of the curve immediately after removal of the isotope syringe and needle from the visual field of the detector. Compartment analysis was performed when the elimination curve was of the multi-exponential type. In order to calculate total blood flow of the labelled region the compartments were weighed together by taking the percentage of activity at the end of the injection as judged by extrapolating curve components to time+20 sec. This percentage is a measure of the relative size of compartments within the labelled tissue volume. Regional uterine blood flow (RUBF) then has been calculated according to eq. 1.
where A l and A 2 stand for percent radioactivity at time+20 sec in compartments 1 and 2. F 1 and F2 are blood flows in compartments I and 2. The validity of this type of curve analysis has been discussed in a previous paper (6). In all calculations of blood flows the partition coefficient of skeletal muscle, 0.7 (I)was used. The patients were undergoing radical or conservative surgery because of myomata. Anaesthesia was of the routine type excluding halothane. A semi-open nonrebreathing system was used to prevent rebreathing of isotope. Blood pressure was within normal limits during the operation. The cases are presented together with results in Table I . Statistical analysis was camed out using a pairingdesign test (16).
RESULTS
In 1 1 patients a total of 25 measurements were carried out. From “normal” myometrium only 2 out of 11 curves were of the mono-exponential type. The rest were rnultiexponential curves. In 14 recordings from myomata, 12 were of the monoexponential type and only 2 multiexponential. Curve analysis according to the initial slope method (Table I) gave as a rule lower values than the compartment analysis (Table 11). In the statistical analysis of values according to initial slope a statistically significant difference was seen between “normal” myometrium and myomata (p
DISTRIBUTION OF BLOOD FLOW IN MYOMATOUS UTERI AS MEASURED BY LOCALLY INJECTED '33XENON Lars Forssman Department of Obstetrics and Gynecology (Head Prof. P . Bergman), Ostra sjukhuset, Gothenburg, Sweden
Abstract. Regional blood flow in the myometrium and myomata has been measured during laparotomy in I 1 pa-
tients using locally injected '33Xenon. Blood flow was calculated from the wash-out curves using both initial slope technique and compartment analysis. Assuming equal partition coefficients in myometrium and myomata the following values in ml smin-1. 100 g-1 are seen: initial slope technique-myometrium 15.6f2.29, myomata 5.1 f0.95, compartment analysis-myometrium 20.01f3.21, myomata 5.5f1.16. The blood flow was always lower in myomata than in myometrium of the same uterus. The main reason for the reduction of blood flow per unit weight of uterus in patients with myomata previously reported thus seems to be low blood flow in the myomata. A slight reduction of blood flow in the surrounding myometrium, however, also seems probable.
observations cited above (7, 10) may depend on a generalized slowing of blood flow in the myomatous uterus as a whole, blood flow in myomata and the surrounding myometrium being of about the same magnitude. They may also be the result of a very low blood flow in myomata and only a slight or no reduction in the perfusion of the surrounding myometrium. Previous studies d o not give any information o n blood flow within myomata as compared with normal myometrium in the same uterus. The present work was intended t o compare within the same uterus and a t the same occasion blood flow in myomata and in the intervening myometrium.
In a previous study (7) using the isotope clearance method, it was shown that blood flow per unit weight of myomatous uterus is reduced in compari-
METHODS A N D MATERIAL The isotope clearance method utilising '"Xenon
is in agreement with this idea. Degenerative changes in uterine myomata are frequent and are thought to reflect insufficient blood supply. However, morphological data indicate great variations in vascularity in myomata (3.4, 8, 13). Furthermore the blood vessels of the surrounding myometrium are affected by the myomata. This effect was described by Sampson (14) and in a more recent study by Farrer-Brown et at. (2). By compressing veins myomata may impair drainage of the surrounding myometrium and endometrium. This effect may lead to pathological uterine bleeding. It may also lead to a reduction in blood flow in normal myometrium surrounding myomata. Thus the
solution was injected via the uterine serosa. In a few cases a smaller volume was used-identical volumes injected into both myomata and myometrium. In myomata the injection depth varied with the size of the tumor, but in all cases the isotope was deposited well inside the capsule of the myoma. The injections into normal myometrium were made at a depth of 0.5 to 0.7 cm from the serosa. The needle was as a rule held obliquely to the surface to ensure a needle track of at least 0.7 to 1 cm. The injection needle had an outer diameter of 0.4 mm. No aspiration was made prior to isotope injection. Injection time was 20 sec and the needle was left in situ for another 20 sec in order to minimize the risk of leakage through the needle track. Recording was carried out as described for intraarterial injections (5). In all cases at least two recordings were carried out. Since remaining isotope from previous injections might interfere with following recordings, old
was
Acta Obstet Gynecol Scand 55 (1976)
102
Lars Forssman
isotope depots were shielded with lead so that they were not seen by the detector. Two types of curve analysis were performed. The initial slope method for curve analysis was applied on all curves using the initial portion of the curve but disregarding any steep fall of the curve immediately after removal of the isotope syringe and needle from the visual field of the detector. Compartment analysis was performed when the elimination curve was of the multi-exponential type. In order to calculate total blood flow of the labelled region the compartments were weighed together by taking the percentage of activity at the end of the injection as judged by extrapolating curve components to time+20 sec. This percentage is a measure of the relative size of compartments within the labelled tissue volume. Regional uterine blood flow (RUBF) then has been calculated according to eq. 1.
where A l and A 2 stand for percent radioactivity at time+20 sec in compartments 1 and 2. F 1 and F2 are blood flows in compartments I and 2. The validity of this type of curve analysis has been discussed in a previous paper (6). In all calculations of blood flows the partition coefficient of skeletal muscle, 0.7 (I)was used. The patients were undergoing radical or conservative surgery because of myomata. Anaesthesia was of the routine type excluding halothane. A semi-open nonrebreathing system was used to prevent rebreathing of isotope. Blood pressure was within normal limits during the operation. The cases are presented together with results in Table I . Statistical analysis was camed out using a pairingdesign test (16).
RESULTS
In 1 1 patients a total of 25 measurements were carried out. From “normal” myometrium only 2 out of 11 curves were of the mono-exponential type. The rest were rnultiexponential curves. In 14 recordings from myomata, 12 were of the monoexponential type and only 2 multiexponential. Curve analysis according to the initial slope method (Table I) gave as a rule lower values than the compartment analysis (Table 11). In the statistical analysis of values according to initial slope a statistically significant difference was seen between “normal” myometrium and myomata (p
