Myocardial resection is a surgical procedure in which a portion of the heart muscle is removed.
Myocardial resection is done to improve the stability of the heart function or rhythm. Also known as endocardial resection, this open-heart surgery is done to destroy or remove damaged areas. These areas can generate life-threatening heart rhythms. Conditions resulting in abnormal heart rhythms caused by re-entry pathways or aberrant cells are corrected with this treatment.
Areas of the heart involved in a myocardial infarction change in contractility and function, becoming scar tissue that thins and hinders its ability to contract. Removing this diseased area can improve myocardial contractility reversing the severity of chronic heart failure. This procedure has shown promise for patients with chronic heart failure, in order to improve cardiac output and quality of life.
Patients are not limited by age, race or sex when being evaluated for myocardial resection surgery. Patients who experience angina, congestive heart failure, arrhythmias, and pulmonary edema (fluid on the lungs) are candidates for this procedure. Contraindications—conditions in which the surgery is not recommended—include right heart failure, elevated left ventricular enddiastolic pressures, and pulmonary hypertension (high blood pressure in the circulation around the lungs).
After receiving a general anesthetic, an incision will be made in the chest to expose the heart. Cardiopulmonary bypass (to a heart-lung machine) will be instituted since this procedure requires direct visualization of the heart muscle. Since this is a true open heart procedure, the heart will be unable to pump blood during the surgery.
When the exact source of the abnormal rhythm is identified, it is removed. If there are areas around the source that may contribute to the problem, they can be frozen with a special probe to further insure against dangerous heart rates. The amount of tissue removed is so small, usually only 2–3 mm, that there is no damage to the structure of the heart.
Weakened myocardium (cardiac muscle) allows the heart to remodel and become less efficient at pumping blood. The goal is to remove the damaged region of the free wall of the left ventricle along with any involved septum. The heart is then reconstructed to provide a more elliptical structure that pumps blood more efficiently. In some instances a Dacron graft is used to replace the removed myocardium to aid in the reconstruction.
Diagnosis of arrhythmias begins with a Holter monitor that can identify the type of arrhythmia. This is followed by a cardiac catheterization to find the aberrant cells generating the arrhythmia. The patient is then recommended for open-heart surgery to remove the cells generating the arrhythmia.
Diagnosis of chronic heart failure is demonstrated by a cardiac catheterization or nuclear medicine study. During cardiac catheterization, the patient's cardiac function will be measured by cardiac output, ejection fraction and cardiovascular pressures. A nuclear medicine study can demonstrate areas of myocardium that are damaged. Muscle that is akinetic (does not move) will be identified. This information allows the surgeon to identify candidates for myocardial resection.
This is major surgery and should be the treatment of choice only after medications have failed and the use of an implantable cardioverter-defibrillator (a device that delivers electrical shock to control heart rhythm) has been ruled out along with medical therapy.
Prior to surgery, the physician will explain the procedure and order blood tests of the formed blood elements and electrolytes.
Immediately after surgery, the patient will be transferred to the intensive care unit for further cardiac monitoring. Any medications to improve cardiac performance will be weaned as necessary to allow the native heart function to return. The patient will be able to leave the hospital within five days, assuming there are no complications. Complications may include the need for intraaortic balloon pump ventricular assist device , surgical bleeding, and infection.
The risks of myocardial resection are based in large part on the patient's underlying heart condition and, therefore, vary greatly. The procedure involves opening the heart, so the person is at risk for the complications associated with major heart surgery, such as stroke, shock, infection, and hemorrhage. Since the amount of myocardium to remove is not precise, a patient may demonstrate little benefit in cardiac performance. If not enough or too much tissue is removed, the patient will continue to have heart problems.
General anesthetic with inhalation gases should be avoided as they can promote arrhythmias. Therefore, anesthesia should be limited to intravenous medications.
Post-operative treatment for arrhythmias demonstrates 90% of patients are arrhythmia-free at the end of one year. A study of 245 patients published in 2001, demonstrated a 98% event free survival rate for patients after one year. After five years, 80% of patients had remained event free.
Cardiopulmonary bypass has an associated risk of complications separate from myocardial resection, with age greater than 70 years of age being a predictor for increased morbidity and mortality. In 1999, over 350,000 total procedures were performed using cardiopulmonary bypass.
In the study of 245 patients, ventricular reconstruction by myocardial resection was found to have an associated in-hospital mortality rate of 78.1%.
If myocardial resection is being performed to prevent arrhythmia generation, new techniques allow for minimally invasive procedures to be performed, including radiofrequency ablation performed in an electrophysiology laboratory with mild sedation, instead of general anesthetic.
If ventricular restoration is contraindicated, medical treatment will be continued. Mechanical circulatory assist with a ventricular assist device may be a suitable option. Heart transplant and total artificial heart should also be explored as alternative therapies.
See also Heart transplantation ; Mechanical circulation support .
Hensley, Frederick Jr., et al. A Practical Approach to Cardiac Anesthesia , 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2003.
McGoon, Michael D., ed. Mayo Clinic Heart Book: The Ultimate Guide to Heart Health. New York: William Morrow and Co., Inc., 1993.
Dor, Vincent, et al. "Intermediate survival and predictors of death after surgical restoration." Seminars in Thoracic and Cardiovascular Surgery 13, no. 4 (October 2001): 468–475.
American Heart Association. 7320 Greenville Avenue, Dallas, TX 75231. (800) 242-8721 or (888) 478-7653. http://www.americanheart.org .
Dorothy Elinor Stonely
Allison J. Spiwak, MSBME
Electrophysiologists, cardiac surgeons and cardiologists, specially trained in cardiac electrical signaling and ventricular reconstruction have undergone specific training in these procedures. The number of patients suitable for these procedures are limited so experienced physicians should be sought to provide medical treatment.
Can resection compromise blood supply to heart