Ventricular Septal Rupture Following Myocardial Infarction Author: Shabir Bhimji, MD, PhD; Chief Editor: Brett C Sheridan, MD, FACSUpdated: Dec 1, 2011

BackgroundVentricular septal rupture (VSR) is a rare but lethal complication of myocardial infarction (MI). The event occurs 2-8 days after an infarction and often precipitates cardiogenic shock. The differential diagnosis of postinfarction cardiogenic shock should exclude free ventricular wall rupture and rupture of the papillary muscles. To avoid the high morbidity and mortality associated with this disorder, patients should undergo emergent surgery. Concomitant coronary artery bypass may be required. Developments in myocardial protection and improved prosthetic materials have contributed greatly to successful management of VSR. Long-term survival can be achieved in patients who undergo prompt surgery.

History of the ProcedureLatham first described this condition at autopsy in 1847, but he did not make the association between acquired VSR and coronary artery disease (CAD). Brunn made the first antemortem diagnosis of acquired VSR in 1923, and, in 1934, Sager established the clinical association between MI and VSR.No surgical treatment was available until 1957, when Cooley et al performed the first successful surgical repair of VSR in a patient 9 weeks after the diagnosis. Unfortunately, the patient died 6 weeks later.Principal treatment of postinfarction VSR during the early 1960s consisted of aggressive medical management, although it was well known that survival was rare after medical treatment alone. Surgical therapy was generally reserved for patients who survived at least 6 weeks, primarily to allow for scarring of the edges of the defect. A secure and long-lasting closure was thought to occur if the edges of the VSR were strong enough to hold the sutures.By the late 1960s, early surgical repair was proposed for patients whose conditions were deteriorating despite medical therapy. The timely introduction of better prosthetic material significantly contributed to the successful surgical repair of acute VSR.More recently, improved surgical techniques (eg, infarctectomy), myocardial protection, and better perioperative mechanical and pharmacological support have helped to lower mortality rates. In addition, the development of surgical techniques to repair perforations in different areas of the ventricular septum have led to improved results in the management of patients with postinfarction VSR.

EpidemiologyFrequencyRupture of the interventricular septum is an uncommon complication of MI. Although autopsy studies reveal an 11% incidence rate of myocardial free wall rupture after MI, septal wall perforation is much less common, occurring at rate of approximately 1-2%.VSR occurs in a zone of necrotic myocardial tissue, and it usually occurs within the first 10-14 days. Clinical studies report an average time of 2.6 days from infarction to septal rupture. However, recent data suggest that the initial treatment of MI with thrombolytics may affect both the time between infarction and septal rupture and outcome. The early use of thrombolytic agents may lead to reopening of the occluded vessels, thus reducing the incidence of VSR.

The age range of patients who sustain a postinfarction VSR is wide, from 44-81 years. Men are affected more commonly than women, although septal rupture is more common in women than would be predicted based on the prevalence of CAD alone.

PathophysiologyThe blood supply to the septum originates from branches of the left anterior descending coronary artery, the posterior descending branch of the right coronary artery, or the circumflex artery when it is dominant. An infarction associated with a VSR is usually transmural and extensive. Approximately 60% of septal ruptures occur with infarction of the anterior wall; 40% occur with infarction of the posterior or inferior wall. Posterior VSR may be accompanied by mitral valve insufficiency secondary to papillary muscle infarction or dysfunction. At autopsy, patients with VSR usually show complete coronary artery occlusion with little or no collateral flow. The lack of collateral flow may be secondary to associated arterial disease, anatomic anomalies, or myocardial edema. Sometimes, multiple septal perforations occur. These may occur simultaneously or within several days of each other.Ventricular aneurysms are commonly associated with postinfarction VSR and contribute significantly to the hemodynamic compromise in these patients. The reported incidence rate of ventricular aneurysms ranges from 35-68%, whereas the incidence of ventricular aneurysms alone following MI without VSR is considerably less (12.4%).

PresentationNatural historyThe natural history of postinfarction VSR is greatly influenced by hypertension, anticoagulation therapy, advanced age, and, possibly, thrombolytic therapy. The natural course in patients with postinfarction VSR is well documented and short. Most patients die within the first week; almost 90% die within the first year. Reports indicate that fewer than 7% of patients are alive after 1 year. This grim prognosis results from an acute volume overload exacted on both ventricles in a heart already compromised by a large MI and occasionally by extensive CAD in sites other than that already infarcted. In addition, superimposed ischemic mitral valve regurgitation, a ventricular aneurysm, or a combination of these conditions may be present, which further compromises heart function. The depressed left ventricular function commonly leads to impaired peripheral organ perfusion and death in most patients.A few sporadic reports indicate that some patients with medically treated postinfarction VSR live for several years. Although many medical advances have been made in the nonsurgical treatment of these patients, including intra-aortic balloon counterpulsation (IABCP), these methods have not replaced the need for surgery.

Differential diagnosisAn important diagnostic test for differentiating VSR from mitral valve insufficiency is catheterization of the right heart with a Swan-Ganz catheter. In the presence of a VSR, oxygen concentration between the right atrium and the pulmonary artery is stepped up. In addition, a pulmonary capillary wedge pressure tracing is beneficial for differentiating acute mitral regurgitation from VSR. Left- and right-sided pressure measurements help estimate the degree of biventricular failure and are useful in monitoring the response to perioperative therapy. Although right-sided failure is more common in patients with postinfarction VSR, left-sided failure and refractory pulmonary edema are more prominent in patients with ruptured papillary muscle. However, a third of patients with postinfarction

VSR also have some mitral regurgitation secondary to left ventricular dysfunction. Only rarely is VSR also associated with ruptured papillary muscle.

History and physical examinationUpon auscultation, a loud systolic murmur is heard, usually within the first week after an acute MI. This is the most consistent physical finding of postinfarction VSR. Prior to the development of the murmur, the patient may have been stable after the acute MI. Coincident with the onset of the murmur, the patient's clinical course undergoes a sudden deterioration, with the development of congestive heart failure and, often, cardiogenic shock. The typical harsh systolic murmur is audible over a large area, including the left sternal border and apical area. The murmur sometimes radiates to the left axilla, thereby mimicking mitral regurgitation. A thrill is palpable in approximately 50% of patients.Almost 50% of patients have recurrent chest pain. The differential diagnosis includes VSR and mitral insufficiency secondary to papillary muscle rupture, papillary muscle dysfunction, or left ventricular dilatation.

Summary of features of postinfarction VSR Occurrence is typically 3-8 days after an MI. The sites of rupture are the anterior septum (60%) and the posterior septum (40%). The most consistent finding is a murmur. In the differential diagnosis, exclude mitral regurgitation from papillary muscle rupture. Diagnosis is confirmed with the aid of echocardiography and the presence of a left-to-

right shunt. Catheterization results help determine the extent of CAD. Of patients treated without surgery, 90% die. Surgery must be emergent, even if the patient is stable.[3] All VSRs are closed with a patch and associated coronary artery bypass grafting. The surgical mortality rate for anterior defects is 10-15% and for posterior defects is 30-

35%.

IndicationsIn view of the grim prognosis of medically treated patients, simply the diagnosis of postinfarction ventricular septal rupture (VSR) is an indication for operation. The previous controversy surrounding the timing of surgical intervention is no longer an issue, and most surgeons agree that early surgery should be performed in order to incur the lowest risk of mortality and morbidity. The success of the surgery depends on the prompt medical stabilization of the patient and the prevention of cardiogenic shock.The relative safety of repair 2-3 weeks or more after perforation is apparent from the previous data. Because the edges of the defect have become firmer and fibrotic, repair is more secure and easily accomplished. A successful clinical outcome is related to the adequacy of closure of the VSR; therefore, if possible, search for multiple defects preoperatively and certainly at the time of surgery. Only when the patient is hemodynamically stable should repair be initially delayed, but there must be high degree of certainty that the patient is hemodynamically stable. These patients can suddenly deteriorate and die.The criteria for a delay in surgery include adequate cardiac output, no evidence of cardiogenic shock, an absence of signs and symptoms of congestive heart failure or minimal use of pressor agents to control initial symptoms, an absence of fluid retention,

and good renal function. The natural history of the disease is such that few patients present with these signs and symptoms.In most patients, postinfarction VSR rapidly leads to a worsening of the hemodynamic state, with cardiogenic shock, marked and intractable symptoms of congestive heart failure, and fluid retention. Immediate surgery is usually indicated. The high surgical risk of early repair is accepted because of the even higher risk of death without surgery under such circumstances.Occasionally, a delay in diagnosis and referral occurs. These patients are usually critically ill, and the prognosis is very grim; thus, allowing the natural history of the disease to take its course is prudent.

ContraindicationsGenerally, most patients who experience a postinfarction ventricular septal rupture (VSR) need emergent surgery. However, because of either delayed diagnosis or referral, an occasional patient may be in a state of multiorgan failure and may not be a candidate for surgery. The chances of such a patient surviving an operation are minimal; in these circumstances, supportive medical therapy may be adequate. Patients who are comatose and in cardiogenic shock have a particularly poor prognosis after surgery, and surgery is best avoided in such circumstances.

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Imaging StudiesOn plain chest radiographs, 82% of patients with postinfarction ventricular septal rupture (VSR) demonstrate left ventricular enlargement, 78% have pulmonary edema, and 64% have a pleural effusion. These findings are nonspecific and do not exclude other causes such as a ruptured papillary muscle.M-mode transthoracic and transesophageal echocardiography have recently been used to help diagnose postinfarction VSR. Transthoracic echocardiography findings have been improved with the use of color-

flow Doppler in visualizing the VSR. In addition, echocardiography can help to assess the presence of any mitral valve

pathology.

Other TestsNo ECG features are diagnostic of postinfarction VSR, though ECG indeed provides some useful information. Persistent ST-segment elevation associated with ventricular aneurysm is common. ECG may reveal atrioventricular block in a third of patients. ECG can also be used to help predict the anatomic location of the septal rupture.

Diagnostic ProceduresLeft heart catheterization with coronary angiography is recommended in all stable patients. Good judgment is required when ordering this test because the procedure is time consuming and carries some degree of morbidity in already-compromised patients.

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Medical TherapyInstitute 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.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 TherapyThe 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 are discussed below.

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 replacementOccasionally, 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 aneurysmWhen 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 DetailsPreoperative 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 DetailsPrinciples 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 DetailsPatients 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.

Outcome and PrognosisSurvivalThe operative mortality rate is directly related to the interval between infarction and surgical repair. If repair is performed 3 weeks or more after an infarction, the rate is approximately 20%. If surgery is performed prior to this time, the mortality rate approaches 50%. The most obvious reason for this is the fact that the greater the myocardial damage and hemodynamic compromise, the more urgent the need for early intervention. With the use of an early operative approach, most studies show an overall mortality rate of less than 25%. Mortality rates tend to be lower for patients with anteriorly located ventricular septal ruptures (VSRs) and lowest for patients with apical VSRs. For anterior defects, mortality rates vary from 10-15%; for posterior defects, mortality rates vary from 30-35%.More than half the deaths after surgery for postinfarction VSR are due to cardiac failure. Sudden death is rare, and intractable heart failure can also occur. Other causes of death include cerebral embolism. The functional status of most patients surviving the hospital period is good. Most are within New York Heart Association class I or II.

Risk factors for deathThe most important risk factors for death in the early phase are poor hemodynamics and associated right ventricular dysfunction prior to coming to the operating room. The amount and distribution of myocardial necrosis and scarring are responsible for both. Right ventricular dysfunction results from ischemic damage or frank infarction of the right ventricle and is present when stenosis occurs in the right coronary artery system. The higher mortality rate after repair of defects located inferiorly in the septum is probably related to the higher prevalence of important right coronary artery stenosis. The severity and distribution of coronary artery disease (CAD) are also risk factors. Similarly, advanced age at operation, diabetes, and preinfarction hypertension are risk factors for death in the early phase.

Risk factors for death in patients with postinfarction VSR are summarized as follows: Posteriorly located septal ruptures are technically more difficult to repair and are

associated with profound right ventricular dysfunction. The presence of multiple organ failure is a poor prognostic factor. The presence of cardiogenic shock does not bode well for the patient's survival. A shortened interval between infarction and surgery usually indicates the patient is

considered more ill, which imparts more risk for death.

Residual and recurrent VSRResidual ventriculoseptal defects (VSDs) have been noted early or late postoperatively in 10-25% of patients. These residual defects are easily diagnosed with the aid of color-flow Doppler investigations. Residual VSDs may be attributable to the reopening of a closed defect, the presence of an overlooked VSD, or the development of a new septal perforation during the early postoperative period. Reoperation is required for closure of such residual defects when the Qp-to-Qs ratio is greater than 2. When these VSDs are small and asymptomatic, a conservative approach may be recommended because spontaneous closure can occur.

Percutaneous closurePercutaneous techniques have been used successfully to close some congenital VSDs. Technical improvements in experimental devices to close intracardiac shunts are being made to treat postinfarction VSR or residual shunts after primary repair. A balloon catheter introduced percutaneously has been used to abolish the shunt in poor-risk patients.

Future and ControversiesAdvances in the management of postinfarction ventricular septal rupture (VSR) have helped significantly decrease the operative mortality rate. In current practice, postinfarction VSR is recognized as a surgical emergency and the presence of cardiogenic shock is an indication for intervention.The addition of coronary artery bypass grafting has helped improve long-term survival. Surgery is performed using a transinfarction approach, and all reconstruction is performed with prosthetic materials to avoid tension. Technical improvements in myocardial preservation and cardioplegia have helped decrease postoperative bleeding and preserve ventricular function. In current practice, patients undergoing shunt repair tend to be older and are more likely to have received thrombolytic agents, which may complicate repair. After successful repair, survival and quality of life are excellent, even in patients older than 70 years.

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