الفهرس 
Acknowledgement
Neonatal heart physiological considerationsOnly 14 pages are availabe for public view
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Abstract
All open-heart procedures carry risks related to the use of cardiopulmonary bypass. The safety of cardiopulmonary bypass has improved significantly over the years. Major complications are now exceedingly rare. Bypass times up to four to eight hours are well tolerated.
The risks of bypass itself include inadequate perfusion of organs or tissues, activation of a systemic inflammatory response, and embolization of air or particles. Especially concerning is the potential of embolization to the brain, but this risk should be quite low – less than 1 percent in most cases.
Bleeding is also a risk after open heart surgery. Due to the use of Heparin (a blood thinner) during bypass, bleeding sometimes occurs where we have placed sutures. Usually the bleeding is minimal and easily controlled with medications and bandages. The need for re-operation for bleeding following open-heart operations is low, about 2 percent.
In addition to the risks of bypass, the heart itself can be affected. First, the heart undergoes a period of cold ischemia (no blood flow) during most open-heart operations. Myocardial function may be compromised by this period of ischemia despite efforts to protect the heart muscle using cardioplegia and cooling. Second, the heart’s function may be decreased or “depressed” after surgery. The heart needs time to adapt to new anatomy and physiology after repair. Last, the heart rhythm may also be affected by open-heart procedures. Some patients require temporary or even permanent pacing (stimulation of the heart to assure a normal rhythm).
Success of open-heart surgery is highly dependent on the particular defect being operated upon.
Corrective procedures such as atrial septal defect and ventricular septal defect closures are highly successful with a near-zero percent mortality (or death rate).
Somewhat more complex lesions -- yet ones that are performed often, such as AV canal defects, transposition of the great vessels and tetralogy of Fallot -- carry a risk less than 5 percent.
More complex lesions, such as single ventricle defects, may carry a higher risk in the range of 15 to 20 percent, because one of the ventricles or valves is hypoplastic (underdeveloped).
Other factors can affect these results. For instance, a prematurely delivered newborn suffering from low birth weight and end-organ injury (i.e., kidney failure or liver injury) is at increased risk from open heart surgery.