Dear Vincent:

There is no such thing as a Marian devotion that isolates her alone. Our Blessed Mother always points to her Son. There are two reasons why we venerate the Blessed Mother:

1) because God tells us to through Mary's words at the Annunciation:

(Luke 1:48) ...for he has regarded the low estate of his handmaiden. For behold, henceforth all generations will call me blessed; 

2) because the Blessed Virgin Mary is the Mother of God:

(Luke 1:41-43)  And when Elizabeth heard the greeting of Mary, the babe leaped in her womb; and Elizabeth was filled with the Holy Spirit and she exclaimed with a loud cry, "Blessed are you among women, and blessed is the fruit of your womb! And why is this granted me, that the mother of my Lord [God] should come to me?

3) because in venerating her we honor God:

(Luke 1:46) And Mary said, "My soul magnifies the Lord

4) As the Queen Mother it pleases God that we come to Him through her:

(1 Kings 2:18-19) Bathsheba said, "Very well; I will speak for you to the king." So Bathsheba went to King Solomon, to speak to him on behalf of Adonijah. And the king rose to meet her, and bowed down to her; then he sat on his throne, and had a seat brought for the king's mother; and she sat on his right.

Solomon was the King. Bathsheba was his mother, the Queen Mother. Solomon loves his mother greatly, so much that he bows to her and seats her at his right hand. This is a archetype of the relationship between King Jesus and His Queen Mother, the Blessed Virgin Mary. Jesus loves her so much that she sits at His right hand and is pleased to hear she intercessions for us.

We are a family, and God is pleased when his family helps and intercedes for each other. This is the reason that we can pray to Mary and to the Saints to intercede for us before our King and Lord. 

As to the devotion of the Immaculate Heart of Mary, the Catholic Encyclopedia states:

In order that, properly speaking, there may be devotion to the Heart of Mary, the attention and the homage of the faithful must be directed to the physical heart itself. However, this in itself is not sufficient; the faithful must read therein all that the human heart of Mary suggests, all of which it is the expressive symbol and the living reminder: Mary's interior life, her joys and sorrows, her virtues and hidden perfections, and, above all, her virginal love for her God, her maternal love for her Divine Son, and her motherly and compassionate love for her sinful and miserable children here below. The consideration of Mary's interior life and the beauties of her soul, without any thought of her physical heart, does not constitute our devotion; still less does it consist in the consideration of the Heart of Mary merely as a part of her virginal body. The two elements are essential to the devotion, just as soul and body are necessary to the constitution of man...

 Another Scriptural passage to help in bringing out the devotion was the twice-repeated saying of St. Luke, that Mary kept all the sayings and doings of Jesus in her heart, that there she might ponder over them and live by them.

The encyclopedia article, linked above gives a history of the devotion.

The Eastern Catholic Churches sometimes use this imagery associated with the Immaculate Heart, but it is true that this devotion is primarily Latin. The Eastern Churches and the Orthodox nevertheless have a profound devotion to the Theotokos.(Literal English translations include "God-bearer", "Birth-Giver of God" and "the one who gives birth to God.") The Theotokos is a major subject of Eastern iconography. The Protestants know nothing of the Marian dogmas nor the dogma of the Communion of the Saints and its beauty and grace we receive from God by it. That is because the Protestants have a "Readers Digest", an abridged, understanding of the Faith. The Catholic Church, the Church that was founded by Christ Himself, is the only Church in the fullness of the Faith that God wants us to have.

The bottomline is that the Heart of Mary represents the heart of a mother whose heart is pierced by the death of her son. Mary participated in the suffering of her son. Her heart is a symbol of her interior life, "her joys and sorrows and hidden perfections, and above all, her virginal love for her God, her material love of her Divine Son, and her motherly and compassionate love of her sinful and miserable children here below."

Mary is our mother, too. Jesus proclaimed that from the Cross, "...he said to his mother, 'Woman, behold, your son!'. Then he said to the disciple, 'Behold, your mother!’" (John 19:26-27). Pope John Paul II wrote about this in his, To the Disciple he Said, Behold Your Mother.

Do we not cherish the heart of our own mothers? It is their heart that loves us and nurtures us and sustains us. The heart of Mary does that for us in much greater ways for Mary's heart leads us directly to her Son.

What is the definition and the meaning of the Heart? According to the Bible, the heart is the centre not only of spiritual activity, but of all the operations of human life. The process of salvation begins in the heart by the believing reception of the testimony of God, while the rejection of that testimony hardens the heart (Ps. 95:8; Prov. 28:14; 2 Chr. 36:13). The heart is the "home of the personal life," and hence a man is designated, according to his heart, wise (1 Kings 3:12, etc.), pure (Ps. 24:4; Matt. 5:8, etc.), upright and righteous (Gen. 20:5, 6; Ps. 11:2; 78:72), pious and good (Luke 8:15), etc. (Source: Heart Christian Symbol)

I hope this has help you in some small way.

God Bless,
Bro. Ignatius Mary