The average human heart which weighs 300 -400 grams . Contrary  to the popular perception heart is not purely a muscular organ. In fact myocytes constitutes only 30% of heart mass. Rest formed by

1.Fibroblasts

2.Endothelial cells

3.Purkinje cells

4.Interstitial cells

5.Collagen

6.Fibrous skeleton

7.Extracellualr matrix.

Why is this important to recognise ?

Cardiac failure is not synonymous with myocardial failure .

Many times cardiac failure is due to supporting structure failure like in connective tissue disorders.

Exceesive fibroblast proliferation and resulting in fibrosis of heart.

Cardiac interstitial failure is new emerging clincal entity.

In future individual cell based therapy will aim  at replacing specific cells that are defective or depleting.