**4. Diagnosis**

role of percutaneous closure devices. Unfortunately, despite early repair and improvement in techniques and peri-operative management, the short and long-term outcomes remain

Post-myocardial infarction ventricular septal defects (PI-VSD) were described first at autop‐ sy [30]. It was not until 1923 that the pre-mortem pathophysiology was understood [7]. [40], described the association with coronary artery disease and acute myocardial infarction [40]. The first report of a surgical repair came in 1956 when Denton Cooley described a patient 9 weeks after the initial diagnosis who underwent operative intervention [12]. With advances in the peri-operative and intra-operative management of the cardiovascular surgery patients there were reports of survival in what was previously felt to be an inherently fatal problem. Most of the successful operative cases occurred in patients who presented in congestive heart failure weeks after their initial acute event. Based upon these experiences, for many years it was the belief that operative management should be delayed as long as possible to allow for scaring of the necrotic myocardium to provide for a more stable repair. As experi‐ ences grew early repair was advocated, particularly in stable patients before hemodynamic

The incidence of PI-VSD has decreased dramatically over the years with advances in myo‐ cardial reperfusion and early revascularization strategies. Historically, up to 5% of AMI were associated with mechanical complications such free-wall ruptures, papillary muscle rupture, and PI-VSD [1]. With advanced in therapies that advocate early and aggressive at‐ tempts at reperfusion of the acute ischemic myocardial – such as thrombolytic therapy, early percutaneous interventions with coronary stenting (PCI), and, rarely, emergent coronary ar‐ tery bypass surgery (CABG) – the overall presentation of mechanical complications, such as PI-VSD, has decreased significantly. Large multi-center studies evaluating the pathophysiol‐ ogies of acute myocardial infarctions have shown a current incidence of approximately 0.2% of all AMI. In patients who present late or in whom there is a delay in therapy and there is a resulting increase in myocardial damage, this incidence increases up to 2%. Despite the low risk of developing a PI-VSD, it accounts for a disproportionally high mortality rate. Five per‐ cent of all early deaths after AMI are attributed directly to the complications of PI-VSD [36].

The timing of the development of a PI-VSD can be quite variable. The average time to clini‐ cal presentation is between 2 and 4 days. However, some patients can present as early as a

less than ideal.

294 Principles and Practice of Cardiothoracic Surgery

**2. History**

deterioration and associated multi-organ failure.

few hours after AMI or as long as several weeks.

**3. Clinical Presentation**

The diagnosis of a PI-VSD must be considered in any patient presenting with hypotension, cardiogenic shock, or respiratory failure, particularly in the setting of a patient who other‐ wise had been doing well, either during or after an AMI. A PI-VSD presents in a similar manner as other mechanical complications of AMI, such a papillary muscle rupture with acute mitral regurgitation, free wall rupture with tamponade, or severe LV failure and pul‐ monary edema. The initial diagnosis must be suspected during initial investigations during a comprehensive work-up.

Patients often complain of recurrent chest pain. The characteristics of the pain are often dif‐ ferent than their initial presentation and are typically related to the onset or recurrence of myocardial necrosis. Often a new systolic murmur will develop and it can be harsh, pansys‐ tolic, and often-best auscultated at the left lower sternal border. Patients can often have a bundle branch block from disruption of the septal conduction system. Hemodynamic deteri‐ oration can be quick and there can be a rapid progression to cardiogenic shock.

**Figure 1.** Representative cardiac catheterization in which contrast is injected during left ventriculography crosses the defect into the right ventricle. Contrast flowing into the pulmonary artery is then diagnostic for a ventricular septal defect.

With the acute clinical decompensation, a rapid evaluation of potential causes is critical. Un‐ like other mechanical complications, such as papillary muscle rupture, PI-VSDs will have imaging confirming a left to right shunt – such as contrast injected into the left ventricle dur‐ ing catheterization crossing the defect into the RV and entering into the pulmonary arteries (Figure 1). Likewise, oxymetric assessment with right heart catheterization will demonstrate a "step-off" from the mixing of de-oxygenated RV blood with the oxygenated LV blood. Quantitative assessment of Qp:Qs can correlate with the size, and more importantly – the physiologic consequences, of the defect.

after their initial acute coronary insult, it is hard to argue the need for repeat cardiac catheter‐ ization if the diagnosis is clear and the coronary anatomy is defined. Conversely, repeat catheterization might suggest an alternative, and potentially more likely, diagnosis such as acute stent thrombosis, coronary dissection, or disruption of an already unstable plaque.

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Transthoracic echocardiography (TTE) remains the cornerstone of the non-invasive assess‐ ment of PI-VSD [28]. TTE is indicated in any patient who presents with acutely impaired ventricular function or in unexplained hemodynamic deterioration [9]. Echocardiography has the benefit of being able to assess both left and right ventricular function, the presence of co-existing and confounding valvular diseases – typically mitral and/or tricuspid regurgita‐ tion, and with color flow imaging it can be 100% specific and sensitive in diagnosing a PI-VSD. Despite the utility of transesophageal echocardiography in the acute assessment of an unstable patient, a high index of suspicion is needed when looking for a PI-VSD as tradition‐ al echo windows might miss a small or apical defect. Large pericardial effusions might sug‐

**Figure 2.** Transesophageal echo, 4-chamber view, demonstration an apical VSD with shunt from the left ventricle (LV) to the right ventricle (RV). The left atrium (LA) is also shown to illustrate the typical relationship of the defect to the

While the diagnosis is often made at the time of initial cardiac catheterization or echocar‐ diography, occasionally a PI-VSD may be encountered as an incidental finding during other diagnostic imaging. While patients might be too hemodynamically unstable or the presence of an intra-aortic balloon pump might contraindicate cardiac MRI, with the growing indica‐ tions and utilization of MRI for operative planning, PI-VSD might be encountered. Patients

**4.2. Echocardiography:**

gest an associated free wall rupture.

**4.3. Cardiac Magnetic Resonance Imaging:**

mitral valve.

#### **4.1. Cardiac Catheterization:**

Without a doubt, the value of early cardiac catheterization and coronary angiography in the setting of acute myocardial ischemia is well established and standard of care. In patients whom the diagnosis of a PI-VSD is suspected this test can also be diagnostic. Because a sep‐ tal defect is often with extensive and acute ischemia of a large territory of myocardium, it is not uncommon that the catheterization findings are different from patients with a history of chronic coronary artery disease in which compensatory development of septal collaterals have had time to develop. During the acute presentation, the findings often suggest a com‐ plete occlusion of a large coronary artery in the setting of relatively minimal disease. Single vessel disease is found in 64% of patients. The left anterior descending (LAD) artery is often the culprit vessel and this explains why anterior or apical septal defects are found in 60% of cases. Conversely, acute occlusions of a dominant right coronary or circumflex artery ac‐ counts for the remaining cases involving the posterior septum. Seven percent have concomi‐ tant double vessel disease, and 29% have triple vessel disease.

As mentioned above, quantitative assessment of oxygen step-offs, when performed, will demonstrate an increase in the partial pressure of oxygen (PaO2) between the right atrium and ventricle – diagnostic of left to right shunting. Left ventricular contrast injections, al‐ though less likely to be performed in a deteriorating patient secondary to the concern that additional contrast might further injure already compromised renal function, can be diag‐ nostic of a PI-VSD. Contrast injected into the LV will cross the defect (left-right shunt) and flow into the pulmonary arterial tree. This "pulmonary arteriogram" is characteristic for a VSD (Figure 1, see above)

Arguments against mandatory catheterization suggest that in a clinically deteriorating pa‐ tient in whom the diagnosis is clear it only delays surgical management, the dye load may worsen already impaired renal function, and some reports suggest that considering the pat‐ terns of coronary disease typically encountered that coronary revascularization is a risk fac‐ tor for a poor outcome [33]. Despite these theoretical arguments, from a practical standpoint it is hard to argue the clear benefits of defining the coronary anatomy prior to a surgical intervention aimed at treating a complication of impaired coronary blood flow – particular‐ ly given the importance of optimal and complete revascularization. Since these patients have already undergone catheterization as part of the initial management of their initial ischemic event, the question whether to proceed with catheterization (or repeat catheterization) is rarely encountered. However, as many of the patients develop septal defect several days (or weeks) after their initial acute coronary insult, it is hard to argue the need for repeat cardiac catheter‐ ization if the diagnosis is clear and the coronary anatomy is defined. Conversely, repeat catheterization might suggest an alternative, and potentially more likely, diagnosis such as acute stent thrombosis, coronary dissection, or disruption of an already unstable plaque.

#### **4.2. Echocardiography:**

With the acute clinical decompensation, a rapid evaluation of potential causes is critical. Un‐ like other mechanical complications, such as papillary muscle rupture, PI-VSDs will have imaging confirming a left to right shunt – such as contrast injected into the left ventricle dur‐ ing catheterization crossing the defect into the RV and entering into the pulmonary arteries (Figure 1). Likewise, oxymetric assessment with right heart catheterization will demonstrate a "step-off" from the mixing of de-oxygenated RV blood with the oxygenated LV blood. Quantitative assessment of Qp:Qs can correlate with the size, and more importantly – the

Without a doubt, the value of early cardiac catheterization and coronary angiography in the setting of acute myocardial ischemia is well established and standard of care. In patients whom the diagnosis of a PI-VSD is suspected this test can also be diagnostic. Because a sep‐ tal defect is often with extensive and acute ischemia of a large territory of myocardium, it is not uncommon that the catheterization findings are different from patients with a history of chronic coronary artery disease in which compensatory development of septal collaterals have had time to develop. During the acute presentation, the findings often suggest a com‐ plete occlusion of a large coronary artery in the setting of relatively minimal disease. Single vessel disease is found in 64% of patients. The left anterior descending (LAD) artery is often the culprit vessel and this explains why anterior or apical septal defects are found in 60% of cases. Conversely, acute occlusions of a dominant right coronary or circumflex artery ac‐ counts for the remaining cases involving the posterior septum. Seven percent have concomi‐

As mentioned above, quantitative assessment of oxygen step-offs, when performed, will demonstrate an increase in the partial pressure of oxygen (PaO2) between the right atrium and ventricle – diagnostic of left to right shunting. Left ventricular contrast injections, al‐ though less likely to be performed in a deteriorating patient secondary to the concern that additional contrast might further injure already compromised renal function, can be diag‐ nostic of a PI-VSD. Contrast injected into the LV will cross the defect (left-right shunt) and flow into the pulmonary arterial tree. This "pulmonary arteriogram" is characteristic for a

Arguments against mandatory catheterization suggest that in a clinically deteriorating pa‐ tient in whom the diagnosis is clear it only delays surgical management, the dye load may worsen already impaired renal function, and some reports suggest that considering the pat‐ terns of coronary disease typically encountered that coronary revascularization is a risk fac‐ tor for a poor outcome [33]. Despite these theoretical arguments, from a practical standpoint it is hard to argue the clear benefits of defining the coronary anatomy prior to a surgical intervention aimed at treating a complication of impaired coronary blood flow – particular‐ ly given the importance of optimal and complete revascularization. Since these patients have already undergone catheterization as part of the initial management of their initial ischemic event, the question whether to proceed with catheterization (or repeat catheterization) is rarely encountered. However, as many of the patients develop septal defect several days (or weeks)

physiologic consequences, of the defect.

tant double vessel disease, and 29% have triple vessel disease.

**4.1. Cardiac Catheterization:**

296 Principles and Practice of Cardiothoracic Surgery

VSD (Figure 1, see above)

Transthoracic echocardiography (TTE) remains the cornerstone of the non-invasive assess‐ ment of PI-VSD [28]. TTE is indicated in any patient who presents with acutely impaired ventricular function or in unexplained hemodynamic deterioration [9]. Echocardiography has the benefit of being able to assess both left and right ventricular function, the presence of co-existing and confounding valvular diseases – typically mitral and/or tricuspid regurgita‐ tion, and with color flow imaging it can be 100% specific and sensitive in diagnosing a PI-VSD. Despite the utility of transesophageal echocardiography in the acute assessment of an unstable patient, a high index of suspicion is needed when looking for a PI-VSD as tradition‐ al echo windows might miss a small or apical defect. Large pericardial effusions might sug‐ gest an associated free wall rupture.

**Figure 2.** Transesophageal echo, 4-chamber view, demonstration an apical VSD with shunt from the left ventricle (LV) to the right ventricle (RV). The left atrium (LA) is also shown to illustrate the typical relationship of the defect to the mitral valve.

#### **4.3. Cardiac Magnetic Resonance Imaging:**

While the diagnosis is often made at the time of initial cardiac catheterization or echocar‐ diography, occasionally a PI-VSD may be encountered as an incidental finding during other diagnostic imaging. While patients might be too hemodynamically unstable or the presence of an intra-aortic balloon pump might contraindicate cardiac MRI, with the growing indica‐ tions and utilization of MRI for operative planning, PI-VSD might be encountered. Patients with low ejection fractions, cardiomyopathies, or suspicion for unusual cardiac anatomy, might have cardiac MRI performed to assess for myocardial viability, fibrosis, or valvular pathology. In these patients, a PI-VSD may be an unsuspected finding (Figure 3). Although there is little experience describing the role of cardiac MRI in PI-VSDs, using concepts de‐ rived from the literature on congenital shunts and defects, cardiac MRI might be of value in assisting in defining the extent of the defect, the shunt fraction, right ventricular function, and other associated pathophysiology [17]. Cardiac MRI might be of additional value in sit‐ uations of questionable catheterization or echocardiographic results or in the assessment of the post-operative patient when a residual shunt is suspected. Nevertheless, MRI is, in gen‐ eral, not considered a first-line diagnostic imaging tool.

pathways to insure a complete repair [18] and the observation that most defects are proba‐ bly larger than they initially appear. Incomplete closure of residual or secondary defects can account for post-operative recurrences. Transmural infarcts can be quite extensive with de‐ fects developing to several centimeters in diameter and can often involve extensive areas of the left ventricular free wall and potentially the annular structures of the mitral valve. For complex defects, as blood dissects through the necrotic myocardium there can be further ex‐ pansion and damage with loss of cellular integrity. With local cellular destruction there is fragmentation with degeneration of myocytes with enzymatic digestion and destruction. In patients who survive the acute presentation, up to 66% develop chronic ventricular aneur‐ ysms and a third will have significant functional mitral regurgitation from the secondary ef‐

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Interestingly, and clearly an area of further study, the pathologic consequences and out‐ comes of surgery of anterior and posterior defects are different in ways beyond what can be explained by the varying degree of shunting. Autopsy studies have shown that anterior PI-VSDs were associated with 33% of the LV and only 10% of the RV being infarcted, while posterior defects were associated with only 20% of the LV and 33% of the RV being infarcted [15]. Particularly considering the acute pressure/volume overload and associated RV failure, it becomes understandable why posterior based defects are associated with a worse prognosis.

The natural history of untreated PI-VSD is also poorly understood. As advances in the acute and chronic management of coronary artery disease continues to evolve, so does complica‐ tions of CAD such as AMI. In general, 25% of patients with PI-VSDs die within the first 24 hours [6]. Death is most commonly related to pre-existing comorbidities and the potentially irreversible and severe heart failure that comes from not only the acute pump failure from the inciting infarct but also the significant acute left to right heart shunting that only com‐ promises systemic perfusion further. The sudden increase in pulmonary overcirculation also contributes to the development of significant right heart failure. For those patients who sur‐ vive the acute event, 1, 2, and 4-week survival is 50%, 35%, and 20% respectively [31]. It is easy to appreciate that those patients who survive the first month may have inherently fa‐ vorable variables that might further self-select for a good post-operative outcome. Pro‐ longed untreated survival has been reported with up to 7% of patient surviving to 1 year –

obviously the physiologic insult and over-circulation is minimal in these rare cases.

The mere presence of a PI-VSD is considered an indication for surgery with the majority of patients undergoing urgent or emergent operative intervention [38]. The primary goal of VSD closure is to reduce the end-organ damage from the combined insults of acute right

fects on the ventricular free wall.

**6. Natural History**

**7. Timing/Indications for surgery**

ventricular overload/failure and systemic cardiogenic shock.

**Figure 3.** Cardiac MRI demonstrating an apical defect. Gated cine images indicated a left to right shunt in which quantitative assessment can be used to calculate the shunt fraction and size of the defect.
