eMedicine Specialties > Thoracic Surgery > Cardiac
Ventricular Septal Rupture Following Myocardial Infarction: Treatment
Updated: Nov 7, 2008
Treatment
Medical Therapy
Institute pharmacological therapy in an attempt to hemodynamically stabilize the patient. The purpose of the therapy is to reduce afterload on the heart and to increase forward cardiac output.
Vasodilators may be used in an attempt to decrease the left-to-right shunt associated with the mechanical defect and thus increase cardiac output. Intravenous nitroglycerin can be used as a vasodilator and may provide improved myocardial blood flow in patients with significant ischemic cardiac disease.
Inotropic agents used alone may increase cardiac output; however, without changes in the ratio of pulmonary to systemic flow (Qp-to-Qs), they markedly increase left ventricular work and myocardial oxygen consumption. The profound level of cardiogenic shock in some patients precludes vasodilator treatment, often necessitating vasopressor support. Inotropic agents and vasopressors markedly increase left ventricular work and myocardial oxygen consumption. Vasopressor agents also increase systemic afterload and further increase the Qp-to-Qs ratio, thus lowering cardiac output and greatly augmenting myocardial oxygen consumption. Nevertheless, the profound level of cardiogenic shock in some patients may preclude vasodilator treatment.
Intra-aortic balloon counterpulsation (IABCP) offers the most important means of temporary hemodynamic support. IABCP reduces left ventricular afterload, thus increasing systemic cardiac output and decreasing the Qp-to-Qs ratio. IABCP also facilitates diastolic augmentation with an increase in coronary blood flow, resulting in improved oxygen supply. IABCP is not a substitute for urgent intervention, and, in patients with cardiogenic shock, it should be followed by immediate intervention. Patients with ventricular septal rupture (VSR) do not die of cardiac failure; they die as a result of end organ failure. Only by shortening the duration of shock can the high risk of mortality be prevented.
Achieving hemodynamic stability prior to surgery is very beneficial, but prolonged attempts to improve the patient's hemodynamic status can be hazardous.5
This aggressive approach often results in temporary stability of these extremely ill patients; however, in general, these benefits are brief and patients may rapidly deteriorate. Therefore, early diagnosis and rapid surgical intervention should be planned. Only approximately 10-15% of patients can be treated with conservative treatment for a period of 2-4 weeks, after which surgery can be performed at a greatly reduced risk.
Surgical Therapy
The first operations for repair of postinfarction VSR used an approach through the right ventricle, with an incision of the right ventricular outflow tract as was used to repair some congenital ventriculoseptal defects (VSDs). This approach proved inadequate because of limited exposure for lesions at the apex of the heart, injury to normal right ventricular muscle, interruption of coronary collateral vessels, and failure to excise the infarcted tissue.
Subsequently, a transinfarction approach was described. This technique, first pioneered by Heimbecker, incorporates infarctectomy, aneurysmectomy, and repair of the ventricular septal perforation. The technique of closure of these defects has resulted in several procedures. The choice of procedure is determined by the location of the defect. Most defects are anteroapical, and closure uses a technique of buttressing the defect with viable muscle from the adjacent anterior left ventricular wall. Smaller defects located high in the ventricular septum are closed with a Dacron patch.
The less common high posterior septal or inferior defect is approached through the inferior portion of the heart, usually in the distribution of the posterior descending coronary branch of the right coronary artery. The incision is made in the area of maximal infarction, which is usually on the right ventricular side of the septum. A well-proven principle of repair of these defects is the use of a synthetic patch closure to prevent tension.
Associated Procedures
Concomitant coronary artery bypassControversy surrounds the issue of whether to perform coronary artery bypass in patients undergoing emergent postinfarction ventricular septal repair. Some authors have shown no benefit to coronary artery bypass surgery and have found that cardiac catheterization in ill patients is time consuming and risks contrast injury to the kidney. However, others have used a selective approach to cardiac catheterization.
In patients who probably do not have a history of angina or previous MI, cardiac catheterization is deferred. Cardiac catheterization findings help confirm and quantitate the presence of a shunt and reveal pulmonary artery pressure and resistance values. The left ventriculogram helps determine the location and number of VSDs, define left ventricular function, and also assess mitral valve function. Most surgeons perform bypass in patients with VSR and have shown a significant improvement in survival.
Mitral valve replacement
Occasionally, significant mitral valve regurgitation may be associated with acute VSR, particularly when the infarction is posterior. The mitral valve must be replaced under such circumstances. Replacement is usually best accomplished through the left ventriculotomy incision using interrupted, pledged mattress sutures.
Left ventricular aneurysm
When a left ventricular aneurysm is associated with postinfarction VSR, it is excised as the initial step in the surgery. After repair of the VSR, the aneurysm is generally repaired.
Preoperative Details
Preoperative management is directed toward rapid resuscitation and stabilization of the patient and preparation for surgery. The goals are to (1) reduce systemic vascular resistance (thereby decreasing the left-to-right shunt), (2) maintain a stable cardiac output and blood pressure, and (3) maintain coronary artery blood flow.
Preoperative treatment of patients with postinfarction VSR is summarized as follows:
- Transfer patients to an intensive care unit for resuscitation.
- Place a Swan-Ganz catheter to help manage hemodynamics.
- Decrease the systemic vascular resistance and the left-to-right shunt with vasodilators.
- Maintain cardiac output and organ perfusion with inotropic agents.
- Maintain coronary artery blood flow.
- Use IABCP to decrease myocardial oxygen consumption, decrease afterload, and increase coronary artery perfusion.
- Use mechanical ventilation as required.
- Use echocardiography to help determine the site of septal rupture.
- Use cardiac catheterization to help determine the presence of coronary disease.
Intraoperative Details
Principles associated with the evolution of techniques for the closure of postinfarction VSR are summarized as follows:
- Determine and understand the anatomy and location of the VSR and any associated coronary artery pathology.
- Expeditiously establish hypothermic total cardiopulmonary bypass, and pay attention to myocardial protection with cardioplegia.
- Use a transinfarction approach to the VSR, with the site of ventriculotomy determined by the location of the transmural infarction.
- Inspect the papillary muscles, and concomitantly replace the mitral valve only if frank papillary muscle rupture is present.
- Trim the left ventricular margins back to viable muscle.
- Conservatively trim the right ventricular muscle.
- Close the VSR without tension with the use of prosthetic material.
- Buttress the suture line with Teflon pledgets.
Postoperative Details
Patients who require an intra-aortic balloon pump preoperatively appear to benefit from postoperative support with the device for 24-72 hours. Some of these patients demonstrate a small persistent or recurrent left-to-right shunt. Because of the large amount of prosthetic material used to repair the septal perforation, anticoagulation therapy in these patients is recommended by some surgeons for a period of 6-8 weeks.
Follow-up
For excellent patient education resources, visit eMedicine's Heart Center. Also, see eMedicine's patient education articles Ventricular Septal Defect and Heart Attack.
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References
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Further Reading
Keywords
VSR, ventricular rupture, ventricle rupture, post-MI VSR, post MI ventricular rupture, postinfarct ventricular septal rupture, postinfarct VSR, postinfarction VSR, anteroapical septal rupture, posterior septal rupture, transmural infarction, loud systolic murmur, left-to-right shunt, left heart catheterization, intraaortic balloon pump, intra-aortic balloon pump, IABP, intraaortic balloon counterpulsation, IABCP, intra-aortic balloon counterpulsation cardiogenic shock, ventriculotomy, aneurysmectomy, patch repair, coronary revascularization, recurrent ventricular septal defect, ventriculoseptal defect, VSD, ventricular septal defect, congestive heart failure, CHF, coronary heart disease, CAD, heart failure
