Shunting With Nitroglycerin

Shunting of Blood

• Nitroglycerin's primary effect is dilation, or opening up, of the large veins of the body. Most commonly it dilates the veins of the legs, thus allowing blood to be shunted or redirected to this part of the body. Nitroglycerin achieves its action by relaxing the smooth muscle found in blood vessels; this, in turn, allows the vessel to open up.
  
  

Shunting in Chest Pain

• Recurrent chest pain may indicate that there is a blockage in one of the heart vessels. As a result, insufficient blood is being supplied to the heart cells, and they cannot receive oxygen and nutrients. This causes cell damage and is manifested as chest pain. Nitroglycerin helps to relieve chest pain because it dilates the large veins of the body and allows blood to pool there. Since there is less venous blood going to the heart, the heart will not need to contract and expand as much. This will decrease the heart cells' metabolism, relieving the chest pain.
  
  

Shunting in a Heart Attack

• With a heart attack, there is active death of heart cells, because there is complete occlusion of the heart's vessels and it receives little to no oxygen. Nitroglycerin provides relief by diverting the venous blood away from the heart. This lowers the expansion of the heart, decreasing energy demands. Additionally, nitroglycerin dilates the arterial blood vessels and helps to shunt blood toward vital organs, so that they still receive oxygen and nutrients even if the heart cannot pump as well.
  
  

Shunting in Heart Failure

• Heart failure is a state where the heart cannot pump blood forward to the rest of the body. As a result, blood begins to pool and flows retrograde, back into the lungs. Common symptoms are shortness of breath and coughing. Nitroglycerin helps treat heart failure symptoms by opening up the arteries that exit the heart. The blood is then shunted away from the lungs and flows anterograde, out of the heart. Nitroglycerin also dilates the body's large veins and shunts blood away from entering the heart. This also prevents worsening of heart failure symptoms.