What Is the Mustard Procedure?
The Mustard procedure is a treatment intervention carried out in individuals with transposition of the great arteries (TGA). This technique was first performed in 1963, by Dr. William Mustard, and hence it is named the Mustard technique or Mustard procedure. This technique is preferred for elderly patients born with a cardiac anomaly called TGA. However, it is largely replaced by a novel surgical approach called atrial switch operations, where the interchanged arteries will be surgically brought back to their normal position.
What Is the Transposition of the Great Arteries?
Transposition of the great arteries is an alarming and lethal inborn cardiac defect where the two critical blood vessels will get their positions interchanged. This transposition critically impacts how the heart performs its function. The great arteries involved in this transposition are the pulmonary artery and aorta.
The pulmonary artery brings oxygen-deficient blood from the right lower heart chamber (right ventricle) to the lungs. In the lungs, the blood cells get loaded with oxygen molecules while driving out the carbon dioxide molecules. This oxygen-packed blood then returns to the heart's left upper chamber (left atrium) via another blood vessel called the pulmonary vein. The aorta is concerned with transporting oxygen-enriched blood to all other body areas and commences its journey from the lower left heart chamber (left ventricle). This is the normal anatomy of the heart and its associated blood vessels.
In TGA, the position of the aorta and pulmonary artery gets switched. As a result, the oxygenated blood moves to and fro from the lungs while the deoxygenated blood keeps circulating in the body repeatedly. Instead of oxygenated blood, the aorta gets deoxygenated blood, while the pulmonary artery receives oxygen-rich blood. Since the circulating blood's oxygen level is critically low and not getting replenished, it impacts all the cellular functions in the body. An emergency condition entails immediate medical attention to reestablish an oxygenated blood supply.
What Is the Technique Involved in the Mustard Procedure?
In the Mustard procedure, a bidirectional baffle or passage connecting the right and left sides of the heart will be created that permits blood flow in both directions. This provides room for the mixing of oxygen-rich and oxygen-deficient blood. This passage is created by resecting a portion of the wall that separates the two upper heart chambers (atrial septum). Synthetic material is employed for establishing the atrial baffle. This baffle is a communication channel between the widely separated oxygenated and deoxygenated blood.
What Is Mustard Baffle Obstruction and Leakage?
Though the Mustard procedure is often employed for TGA patients, it carries the risk of certain complications. Mustard baffle obstruction and leakage are complications that could arise from the Mustard procedure in the long run.
Mustard baffle obstruction, as the name suggests, hinders blood flow passage through the artificially created baffle. Over time, the baffle wall acquires certain materials, constricting the passage's dimension. Constriction or narrowing of the baffle lumen restricts the two-way blood movement through the baffle. Remarkably collapsed baffle lumen is otherwise called a stenotic baffle. It is similar to that of stenosis of the blood vessel.
In addition to baffle obstruction, the baffle sometimes develops leakage. The baffle is secured with sutures to keep it in the desired position, but these sutures may detach and become wobbly over time. The detached sutures allow leakage, which may enhance the risk of blood clot formation and further complications.
How Mustard Baffle Obstruction and Leakage Can Be Managed?
Mustard baffle obstruction can be managed either conservatively or surgically. The conservative approach is the mainstay for tackling the baffle obstruction, which involves the placement of a stent (a small tube with metal webbings). Stent placement at the constricted area is done with the help of a catheter (a tube that can access the heart through central arteries). This intervention method is known as the percutaneous transcatheter approach. In addition to the transcatheter approach, other percutaneous techniques are employed to correct baffle leakage and obstruction. As these techniques are percutaneous (access through skin incision to advance the catheter into a corresponding central vein), there is no need for intensive surgical exploration.
If the conservative approach does not work, it must be rectified with surgical technique. Surgical correction is quite invasive and extensive. In the case of a leaky baffle, polytetrafluoroethylene-covered stents are employed to check the leakage. Leak closure procedures effectively seal off the baffle leakage, further enhancing the person's longevity. All the baffle-related complications are often dealt with an integrative and multifaceted approach, which ensures prompt rectification of the interposed risks and challenges. Corrective surgeries often pose difficulties, but the doctor's skill and expertise help overcome such challenges.
What Are the Other Complications Associated With the Mustard Procedure?
In addition to baffle obstruction and leakage, certain other potential complications are associated with the Mustard procedure. Heart failure is one of the major risks associated with the Mustard procedure, where the heart cannot drive out sufficient blood needed by the body. Conduction delays are another possible risk in which the incision and resections in the heart chamber impact the conduction system in the heart. It is the conduction system that keeps the heart beating rhythmically and systematically. Impairment in the conduction process impacts the beating rhythm, and at times, the heart beats out of order, giving rise to arrhythmias. TGA patients who have undergone a Mustard procedure tend to experience exercise intolerance. As a result, the person feels severe breathlessness (dyspnea) and is extremely exhausted upon physical exertion. Exercise intolerance is always an indication of trouble with the baffle in patients undergoing the Mustard procedure.
Conclusion
With the introduction of novel treatment modalities for the transposition of the great arteries, the application of the Mustard procedure has turned down dramatically. However, it is still advised to tackle TGA occasionally, especially in elderly individuals. Mustard procedures significantly enhanced TGA patients' survivability before instigating novel interventions. Though issues like baffle leakage and obstruction come up in the long run, they can be effectively tackled by conservative measures. The percutaneous transcatheter approach has proven to be effective in dealing with baffle issues, and it clears the baffle stenosis and seals off the baffle leakages. A multidisciplinary doctors' panel for the correction of baffle issues reassures the success of the intervention and ensures better life quality for the patient with an augmented survival rate.
