Before I start to answer this question let's look and compare the teaching based the 4th Dogma proclaimed by Pope Pius XII and the Easter Orthodox belief:
In Munificentissimus Deus Pope Pius XII defined the dogma of the Immaculate Conception:
By the authority of our Lord Jesus Christ, of the Blessed Apostles Peter and Paul, and by our own authority, we pronounce, declare, and define it to be a divinely revealed dogma: that the Immaculate Mother of God, the ever Virgin Mary, having completed the course of her earthly life, was assumed body and soul into heavenly glory.
Eastern Orthodox belief
Eastern Christians believe that Mary died a natural death, that her soul was received by Christ upon death, and that her body was resurrected on the third day after her death and that she was taken up into heaven bodily in anticipation of the general resurrection. Her tomb was found empty on the third day. "...Orthodox tradition is clear and unwavering in regard to the central point [of the Dormition]: the Holy Virgin underwent, as did her Son, a physical death, but her body – like His – was afterwards raised from the dead and she was taken up into heaven, in her body as well as in her soul. She has passed beyond death and judgement, and lives wholly in the Age to Come.(wikipedia)
Both Roman Catholic and Eastern Orthodox Church embraced the teaching of Mary was Assumed "body & soul", only that St.Pius XII did not include in the 4th Dogma the description of Mary's death while the Eastern Orthodox had described it as "dormition".
Blessed Catherine Emmerich visions and revelation provides a clear narration of event that will point the 4th Dogma of the Catholic Church and the Eastern Orthodox belief are both true and not in conflict.
But before I go to that, I also would like to enumerate the following based on my previous answers regarding "Mary's body was transfigured thru the Holy Eucharist and was given a glorified body while on earth."(My personal reflection was also affirmed by Blessed Emmerich narration)
- Mary's "pre-assumption apparition" pointed to Mary's glorification while on earth was an indication of Her Immaculate Body transformation thru the Holy Eucharist.Mary's immaculate body was "transfigured" thru the Holy Eucharist.
1000 This "how" exceeds our imagination and understanding; it is accessible only to faith. Yet our participation in the Eucharist already gives us a foretaste of Christ's transfiguration of our bodies:
Just as bread that comes from the earth, after God's blessing has been invoked upon it, is no longer ordinary bread, but Eucharist, formed of two things, the one earthly and the other heavenly: so too our bodies, which partake of the Eucharist, are no longer corruptible, but possess the hope of resurrection.
- Mary's Assumption is link closely to the Immaculate Conception. In Immaculate Conception Mary's "redemption" was given in advance in view of the merits of Christ and Her Role as the Mother of the Saviour. In Mary's Assumption the "resurrection of the body" was also given in advance this time Mary merited it as Co-Redemptrix AT THE FOOT OF THE CROSS and the "transfigured body was glorified" while on earth in advance.As the Church teaches the resurrection of the bodies will be on the last day but by the merit of Mary as Co-Redemptrix it was given in advance for Her Role this time as the Mother of all the Redeemed.
"Woman behold your son." (John19:26)
This "glorified body" promised by Christ to all believers the Church teaches in CCC999
999 How? Christ is raised with his own body: "See my hands and my feet, that it is I myself"; but he did not return to an earthly life. So, in him, "all of them will rise again with their own bodies which they now bear," but Christ "will change our lowly body to be like his glorious body," into a "spiritual body":
So, Mary while on earth by participation in the Holy Eucharist possessed a "transfigured body" as affirmed in the vision of Blessed Emmerich.
"When I once more looked down to earth, I saw the Blessed Virgin’s body lying on the couch. It was shining, her face was radiant, her eyes were closed and her arms crossed on her breast.
Soon afterwards I saw her soul, united to her transfigured body, rising out of the tomb far brighter and clearer, and ascending into the heavenly Jerusalem with Our Lord and with the whole glory.
The Dormition accounts by Blessed Emmerich is described as follows;
"Peter approached her and gave her extreme unction, much in the way in which it is administered now. From the boxes which John held he anointed her with holy oil on her face, hands, and feet, and on her side, where there was an opening in her dress so that she was in no way uncovered. While this was being done the Apostles were reciting prayers as if in choir.
"Peter then gave her Holy Communion. She raised herself to receive it, without supporting herself, and then sank back again. The Apostles prayed for a while, and then, raising herself rather less, she received the Chalice from John. As she received the Blessed Sacrament I saw a radiance pass into Mary, who sank back as though in ecstasy, and spoke no more.
"Afterwards I saw the Apostles and disciples once more standing round the Blessed Virgin’s bed and praying. Mary’s face was radiant with smiles as in her youth. Her eyes were raised towards heaven in holy joy.
"Then I saw a wonderfully moving vision. The ceiling of Our Lady’s room disappeared, the lamp hung in the open air, and I saw through the sky into the heavenly Jerusalem. Two radiant clouds of light sank down, out of which appeared the faces of many angels. Between these clouds a path of light poured down upon Mary, and I saw a shining mountain leading up from her into the heavenly Jerusalem. She stretched out her arms towards it in infinite longing, and I saw her body, all wrapped up, rise so high above her couch that one could see right under it. I saw her soul leave her body like a little figure of infinitely pure light, soaring with outstretched arms up the shining mountain to heaven.
"The two angel-choirs in the clouds met beneath her soul and separated it from her holy body, which in the moment of separation sank back on the couch with arms crossed on the breast.
"Seeing her thus entered into the glory of heaven, I forgot the whole scene round her body on the earth.
"When I once more looked down to earth, I saw the Blessed Virgin’s body lying on the couch. It was shining, her face was radiant, her eyes were closed and her arms crossed on her breast. The Apostles, disciples, and women knelt round it praying.
The Blessed Virgin died after the ninth hour, at the same time as Our Lord."
[Blessed Anne Catherine Emmerich, The Life of the Blessed Virgin Mary, ebook p. 223-224.]
After this Mary's soul entering heaven received all the glories the Most Holy Trinity had bestowed upon Her. And since the CCC999 stated that Jesus is the one who will change our lowly bodies into a "glorified body" Mary's soul must ascend to heaven too like Jesus ascending into heaven after His death and then the resurrection. As Blessed Emmerich narrated the following in her visions;
"In the night I saw several of the Apostles and holy women praying and singing in the little garden in front of the rock-tomb. A broad shaft of light came down from heaven to the rock, and I saw descending in it a triple-ringed glory of angels and spirits surrounding the appearance of Our Lord and of the shining soul of Mary. The appearance of Our Lord, whose wound-marks were streaming with light, moved down in front of her soul. Round the soul of Mary, in the innermost circle of the glory, I saw only little figures of children; in the midmost circle they appeared as six-year-old children; and in the outer-most circle as grownup youths. I could see only the faces clearly, all the rest I saw as shimmering figures of light. As this vision, becoming ever clearer, streamed down upon the rock, I saw a shining path opened and leading up to the heavenly Jerusalem. Then I saw the soul of the Blessed Virgin, which had been following the appearance of Our Lord, pass in front of Him and float down into the tomb. Soon afterwards I saw her soul, united to her transfigured body, rising out of the tomb far brighter and clearer, and ascending into the heavenly Jerusalem with Our Lord and with the whole glory. Thereupon all the radiance faded again, and the quiet starry sky covered the land."
Therefore, from Blessed Catherine Emmerich vision the teaching of the Eastern Orthodox Church regarding Mary's "dormition" and dying a natural death, separating the soul from her transfigured body and the "glorified soul" came down from heaven to be reunited to her body to experience "resurrection" was affirmed. Also, the Catholic Church 4th Dogma was not contradicted as Mary's Assumed "body & soul" is elevated in these words "the glorified soul of Mary reunited to Her transfigured body" was assumed into heavenly glories.
In closing, it's worthy to mentioned St.Francis de Sales reflection on the natural death of Mary on how the soul separated from her Immaculate body."It was dying out of deep love" as St.Francis de Sales expressed. Mary deep love and Her Sorrowful & Immaculate Heart longing to be united with His beloved Son Jesus Christ is the driving force behind the separation of Her soul from Her body.What a beautiful death, by dying because of love and ardent longing to be united to Jesus Christ her Saviour and beloved Son..