Visio and C#

I have a Visio ER diagram and want to read the database properties (Columns, Primary, Foreign key, data type) information from an Entity. Also want to find the parent and child tables associated. How can I programmatically achieve it using C#?

I am using Interop Visio library and can read the pages and shape from ER diagram but don't know which functions or methods in Visio interop will let me get properties information from a Shape.

Below is the code I am using and I am not getting any property using it. My ER diagram have just two entities a Parent and a Child table.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Microsoft.Office.Interop.Visio;


namespace Visio_POC
{
public partial class Load_Visio : Form
{
static string strProperties = "";
public Load_Visio()
{
InitializeComponent();
string strFileName = "\\Visio_POC\\POC_Visio.vsd";
Microsoft.Office.Interop.Visio.Application vsApp = new Microsoft.Office.Interop.Visio.Application();
Microsoft.Office.Interop.Visio.Document docVisio = vsApp.Documents.Add(strFileName);
Page pgVisio = docVisio.Pages[1];

printProperties(pgVisio.Shapes);
txtProperties.Text = strProperties;
}

public static void printProperties(Shapes shapes)
{
// Look at each shape in the collection.
foreach (Shape shape in shapes)
{
// Use this index to look at each row in the properties
// section.
short iRow = (short) VisRowIndices.visRowFirst;

// While there are stil rows to look at.
while (shape.get_CellsSRCExists(
(short) VisSectionIndices.visSectionProp,
iRow,
(short) VisCellIndices.visCustPropsValue,
(short) 0) != 0)
{
// Get the label and value of the current property.
string label = shape.get_CellsSRC(
(short) VisSectionIndices.visSectionProp,
iRow,
(short) VisCellIndices.visCustPropsLabel
).get_ResultStr(VisUnitCodes.visNoCast);

string value = shape.get_CellsSRC(
(short) VisSectionIndices.visSectionProp,
iRow,
(short) VisCellIndices.visCustPropsValue
).get_ResultStr(VisUnitCodes.visNoCast);

// Print the results.
//Console.WriteLine(string.Format(
// "Shape={0} Label={1} Value={2}",
// shape.Name, label, value));

strProperties = strProperties + shape.Name + " - " + label + " - " + value;

// Move to the next row in the properties section.
iRow++;
}

// Now look at child shapes in the collection.
if (shape.Master == null && shape.Shapes.Count > 0)
printProperties(shape.Shapes);
}
}
}
}