Heart attack is a condition where a blood clot in the coronary artery blocks the flow of blood to the heart. Consequently, some tissues die due to lack of oxygen. Once dead, these tissues are lost forever as unlike the other body tissues, heart tissues do not regenerate. Though the heart remains crippled and needs medication for life, the remaining tissues should be strengthened to prevent further problems and yoga is the best means to achieve that. Pawanmuktasana series and uthitpadasanaare excellent for the health of the heart. Pawanmuktasana, with its mild stretching and flexible movements, maintains the elasticity of the blood vessels, making the heart’s job of pushing blood into them easier, while uthanapadasanabrings more blood to the organ and makes its tissues healthier. This asana can be done even during the recovery period after a heart attack. Though no prop is required for utthitpadasana, for heart patients, it is necessary to take a support so as not to strain the heart in any way. It is a simple position where lying on the back, the feet are placed on a six inch high platform such as a rolled blanket. To further enhance the effect and hasten the recovery, the following meditative technique should be practiced.
 
Lie down in shavasana–legs apart, hands little away from the body.

Imagine you are breathing in from the left nostril and breathing out from the right one; and then breathing in from the right nostril, breathing out from the left.

When the rhythmic alternate breathing pattern is established, add the mantra sohamto your breath when you breathe in and hamwhen you breathe out.

Practice this for 20 to 30 minutes twice a day.

After a few days, when you are comfortable with the practice, maintain the ratio of 1:2 for inhalation and exhalation. Then the mantra will become: so – ham‘¦m‘¦m‘¦m. You can also practice this meditation for 2/3 minutes to maintain a relaxed state. Source