Thinking Beyond Science

A normal human heart has a “conical screwing motion” by which the blood is effectively pushed from apex to the base and finally to the aorta to be circulated in the body smoothly. But in patients with cardiomyopathy and heart failure, the heart becomes dilated excessively. It looks like a spherical balloon filled with excess fluid that keeps quivering aimlessly. And the pumping is ineffective resulting in most of the blood to remain within the heart itself. Because of reduced blood supply, the vital organs like the brain, the kidneys, and the liver start to malfunction.

Clinical stage which was then called irreversible or end-stage heart failure. This actually meant that the patient’s heart due to various causes like diabetes, high blood pressure, excessive alcohol consumption or infection would fail to maintain proper circulation and would not be able to work as an expert pump, which is the primary function of the heart as an organ.

Cardiac surgery lagged behind other surgeries because of the sheer risk and complexity involved in tackling an organ through scalpels and sutures; that too an organ which was in motion in perpetuity throwing out more than three hundred liters of blood every hour.

Cardiomyopathy, a condition affecting heart muscles. The damage can happen due to several causes such as viral infections, toxins, or metabolic factors. Many a time genetic factors may also be the culprit causing failing or poorly contractile heart.

Cardiopulmonary bypass (CPB) is a basic technique in which a machine is temporarily made to take over the major function of the lungs and the heart during the surgery. This mainly helps in maintaining the oxygen content and the blood circulation of the patient’s body. In fact, the CPB pump is itself often referred to as ‘the pump’ or a heart-lung machine. CPB pumps are operated by perfusionists during surgery. CPB is a major form of extracorporeal circulation. In modern heart-lung machines, an extracorporeal membrane oxygenation is generally used for long-term treatment.

During open-heart surgery, a heart-lung machine is an apparatus that does the work for both the heart (i.e., pumping blood) and the lungs (i.e., oxygenating the blood). The most basic function of the machine is oxygenating the venous supply of blood in the body and then pumping it back into the arterial system which helps in smooth circulation. For the body, CB oxygenates and circulates blood mechanically while bypassing the lungs and heart in a skillful manner. To maintain perfusion to the other organs and tissues of the body, it uses a heart-lung machine while the surgeon tactfully works in a bloodless surgical field. The surgeon properly places a cannula in the right atrium, femoral vein, or vena cava to withdraw blood from the body without any additional hindrance.

Venous blood is completely removed from the body by using a cannula.

Finally, before returning it to the body by a mechanical pump, it is filtered, warmed or cooled, and oxygenated. The drug mixed with the blood is called Heparin and it works as an anticoagulant and makes sure that the blood that is outside the body in circulation does not get clotted.

The whole process is done in a closed-loop model with utmost caution so that any air embolism does not occur, which can be fatal. Lastly, the cannula utilized to return oxygenated blood, most of the time, is inserted in the ascending aorta. But it may also be inserted in the axillary artery. femoral artery, or brachiocephalic artery.

“Hypothermia technique”, on the other hand, reduced metabolic need of the heart and helped in prolonging the time for surgeons to operate avoiding the toxicity of chemical build-up. The heart is a prodigious consumer of metabolic energy of all organs of the body. It is the highest consumer of energy for every gram of tissue. After the heart, the brain is also a major consumer of energy being of significant weight than all the other organs, and this is more so when the body is at rest. These two organs along with the kidneys are the things most prone to injury when the blood circulation and subsequent metabolic supply cease during the open-heart surgery.

Source : A Gift of Heart : Inspiring True Stories about Heart Doctors, Patients and Surgeries by Lingaraj Nath

Goodreads : https://www.goodreads.com/book/show/56788441-a-gift-of-heart