Case of ventricular septal rupture following acute myocardial infarction

Abstract

Ventricular septal rupture is a rare and potentially fatal complication of transmural myocardial infarction. Early identification utilising transthoracic echocardiography significantly improves long term outcomes in these patients. We report on a case of a 77-year-old male who presented with signs and symptoms of cardiac failure and a loud systolic murmur. The patient underwent an initial point-of-care ultrasound which revealed evidence of a transmural myocardial infarction and a high suspicion of an apical ventricular septal rupture. A complete transthoracic echocardiogram confirmed the septal rupture diagnosis and the patient subsequently underwent surgical repair of the ventricular rupture. This case highlights the role of echocardiography in decreasing adverse outcomes in patients with ventricular septal rupture.

Introduction

Ventricular septal rupture (VSR) is a rare and potentially fatal mechanical complication of acute transmural or ST segment elevation myocardial infarction (STEMI). Prior to the era of primary percutaneous intervention, the rate of VSRs was 1–3% in patients presenting with a myocardial infarction (MI) and up to 5% in all fatal MIs¹; however, in the current post thrombolytic era, this has fallen to 0.2%.² VSRs are typically a left ventricular (LV) to right ventricular (RV) shunt across the ventricular septum. VSRs can result in volume overload of the RV, subsequent volume overload of the LV which increases the risk of deterioration to haemodynamic instability and death due to pump failure.^3,4

Due to the risk of rapid deterioration in the acute phase of a VSR post-MI, prompt diagnosis and surgical intervention is essential for improving patient outcomes. Echocardiography is a highly sensitive and specific portable imaging technique that is effective in the risk-stratification of patients with VSRs which aids in the planning of either surgical or percutaneous repair of the septal rupture.¹

Case report

A 77-year-old male presented to the emergency department of a non-cardiac hospital late on a Friday evening following acute onset dyspnoea at rest for six days. He reported no chest pain, was haemodynamically stable, denied any symptoms of syncope and had no reported previous cardiac history. The patient’s medical history included hypertension, long-standing diabetes mellitus type II, cigarette smoking and obesity with a BMI of 30.9. Vital signs on admission included blood pressure 180/110 mmHg, heart rate of 110 bpm, tachypnoea with an oxygen saturation of 94% on room air and his jugular venous pressure was elevated and distended. The patient had a harsh systolic murmur which did not change with respiration. His troponin levels were elevated. The 12-lead electrocardiogram performed on admission showed sinus rhythm with Q waves in the anterior, inferior and lateral leads; T wave inversion in the anterior and lateral leads; ST segment elevation in the inferior leads as well as right bundle branch block with right axis deviation (left posterior fascicular block). A focussed (point of care) echo performed at the bedside in emergency demonstrated possible regional wall motion abnormalities and a high suspicion of the left-to-right shunting at the ventricular apex demonstrated by the presence of flow on colour Doppler across the interventricular septum from the left to right ventricle. The patient was stabilised over the weekend and transferred two days later to a tertiary cardiac surgical hospital to gain access to cardiac catheterisation facilities.

Echocardiography findings

A complete transthoracic echocardiogram (TTE) was requested on admission to the tertiary cardiac surgical hospital to determine functional status post STEMI and to define the origin of the harsh murmur. The echocardiogram showed moderate dilation of the LV cavity (by American Society of Echocardiography chamber quantification criteria) with moderate reduction in global systolic function: Simpson’s biplane LV volume indexed for body surface area of 95 ml/m² with a LV ejection fraction estimated at 30–35%. Regional wall motion abnormalities were consistent with distal left anterior descending (LAD) territory ischaemia with akinesis of the mid and apical segments of the anteroseptum, with an aneurysmal appearance of the apex. The presence of intracavity thrombus was excluded. Figure 1 demonstrates the thinning and aneurysmal appearance of the LV apex from the apical four chamber (Ap4ch) view. Akinesis of the basal inferoseptum and the basal inferior wall was also noted. The RV size was noted as within normal limits. There was preservation of the contractility of the basal and mid segments of the RV demonstrated with the RV systolic annular velocity (S′) being normal at 11 cm/s (normal range >9.5 cm/s)⁵ and the tricuspid annular plane systolic excursion was normal at 1.9 cm (abnormal <1.7 cm). However, hypokinesis of the apical region of the RV was noted. Importantly, a ventricular septal defect was noted on colour Doppler (seen in Figure 2(a)) in the Ap4ch view, which demonstrates left-to-right shunting, with the size of the VSR estimated at 2.9 mm on measurement of the width of the colour Doppler jet (Figure 2(b)). Figure 3 demonstrates a section of discontinuity of the ventricular myocardium which is further evidence of the presence of a VSR. The VSR was interrogated also from the apical long axis view with colour Doppler confirming the left-to-right shunting across the defect at the ventricular apex (Figure 4). A mean pulmonary artery pressure was unable to be estimated to accurately provide an approximation of the pulmonary loading conditions.

Figure 1.

The 2D image of an Ap4ch view.

Figure 2.

(a) and (b) Colour Doppler ultrasound image of the Ap4ch view.

Figure 3.

Zoomed image of the apex from the Ap4ch view.

Figure 4.

Colour Doppler ultrasound image of the apical long axis view.

The patient subsequently underwent diagnostic coronary angiography with a left ventriculogram (LV gram). The angiogram revealed triple vessel disease. There was a 30% proximal lesion in the left main coronary artery as well as complete occlusion at the level of the mid LAD artery (Figure 5). A 50% lesion was noted in the mid portion of the left circumflex artery (Figure 6). The patient’s right coronary artery was occluded with a 100% lesion (Figure 7). On left heart assessment the LV systolic function was severely reduced with an ejection fraction of 15%. Regional wall motion abnormalities were noted on the LV gram with dyskinesia of the apex and akinesia of the basal inferior wall. Importantly, a restrictive VSR was noted.

Figure 5.

Left anterior oblique projection cranial angiogram image showing complete occlusion from the mid LAD artery.

Figure 6.

Right anterior oblique projection caudal angiogram image showing 50% occlusion of the left circumflex coronary artery.

Figure 7.

Right anterior oblique projection angiogram image showing complete blockage of the right coronary artery.

The results from both the echocardiogram and angiogram confirmed the need for immediate surgical intervention to repair the VSR and reperfuse the ventricular myocardium.

Discussion

VSRs are a rare complication post-MI and in most cases are fatal without intervention.⁴ Risk factors for the development of a VSR include advanced age (>65 years), female sex, chronic renal disease and the absence of previous MIs.¹ Septal rupture occurs more frequently with anterior MIs. VSRs associated with inferior MIs often result in a worse prognostic outcome due to the high probability of associated RV dysfunction and thus biventricular failure. The size of a VSR is variable and the morphology can be characterised as simple or complex. Simple defects are defined as a discrete communication across the ventricular septum in which the entry and exit points are positioned at a similar level horizontally and typically occur with anterior infarctions particularly at the level of the ventricular apex.¹ In patients with an inferior MI, the likelihood of RV dysfunction and a complex VSR is increased. Complex VSRs involve multiple channels between the LV and RV which course through the necrotic interventricular myocardium in a winding or serpiginous manner.³ The shunting of the blood through a small sized VSR will cause a loud, harsh systolic murmur, and as a consequence, any patient presenting with an acute MI that has a systolic murmur should be thoroughly investigated to exclude the presence of VSR.³

Collateral circulation can play a role in the risk of developing a VSR, as patients with multi-vessel coronary artery disease are more likely to have progressive, long-standing myocardial ischaemia which has initiated angiogenesis and the formation of sufficient collateral circulation, making these patients less likely to suffer transmural infarction or significant mechanical complications upon MI. In contrast, patients with single-vessel disease are less likely to have extensive collateral circulation and are at greater risk of suffering a transmural infarction with associated mechanical complications.^1,2

Accurate identification and analysis are required of the size, borders and velocity of blood flow through the VSR and associated ventricular function to assist in the determination of appropriate treatment. Due to the high specificity and sensitivity of ultrasound in the detection of a VSR, bedside echocardiography is often the front-line imaging technique utilised in these patients.¹,⁶ An important aspect of the echocardiographic assessment of a patient with a suspected VSR is the need to evaluate the ventricular septum from multiple imaging windows including non-standard or off-axis imaging planes.¹,³,⁶ The VSR will appear on 2D imaging as an area of discontinuity or ‘drop-out’ in the ventricular myocardium. The anatomical size of the shunt can be estimated using 2D calipers to measure from one border of the defect to the other border. Extensive trabeculation of the RV apex can obscure direct 2D visualisation of the septal rupture and thus particular care must be taken in these patients to interrogate the apex from multiple views.³ The presence of an apical aneurysm increases the risk of septal rupture, thus apical aneurysms in patients with a new systolic murmur post anterior MI should be thoroughly evaluated for the presence of a VSR.^3,6

Due to the possibility of inadequate visualisation of a VSR with 2D imaging, colour Doppler should always be used as a complementary imaging modality to evaluate a VSR. The width of the colour Doppler jet can be calipered to provide an estimation of the size of the septal defect.¹ In this patient, the use of colour Doppler from an off-axis apical long axis view (Figure 2(b)) confirmed the presence of a VSR (Figure 2(a)).

In addition, ultrasound enhanced agents (UEAs) can also be used to confirm the presence of post-MI complications (such as VSR) in patients with suboptimal 2D images particularly in patients with limited visualisation of the apex due to body habitus, lack of ability to maintain correct positioning for apical images or complicating clinical factors.⁷ UEAs are an important tool which can substantially increase the accuracy of determination of the presence of intracardiac shunts due to their ability to demonstrate blood flow direction in real-time imaging.⁸ Unfortunately, contrast was not available at the time of the echocardiogram.

Continuous-wave (CW) Doppler can be used to quantify the velocity of blood flow through a simple VSR and using the modified Bernoulli equation estimate the pressure gradient between the left and right ventricles.³ In complex VSRs, the CW Doppler measurement is inaccurate due to the presence of multiple shunts. In addition, the blood velocity information obtained with CW Doppler can be used to estimate the severity of shunting using the Qp:Qs shunt calculation.⁶ A normal shunt ratio is 1:1 which indicates no direct communication between the systemic and pulmonary circulations and that blood volume in each of the circulations is equivalent.⁶ VSR closure is indicated when the Qp:Qs is greater than 1.5 and there is presence of LV systolic or diastolic dysfunction or cardiac failure.⁹ The Qp:Qs in this patient was 1.7 which supported the need for surgical intervention to reduce the risk of deterioration into cardiac failure.

The patient underwent a coronary artery bypass graft with simultaneous Dor procedure to patch the VSR and restore the altered geometry of the apical aneurysm.⁹,¹⁰ The procedure was carried out effectively with complete closure of the VSR, resulting in a positive outcome with the patient surviving the surgery without significant adverse complications. Revascularisation surgery in this patient has reduced the risk of recurrent MI and further complications caused by the VSR in this patient, thus increasing the long term prognostic outcome for this patient.

Conclusion

VSR is a mechanical consequence of a transmural MI which increases the risk of haemodynamic complications that have a high associated mortality rate. Any patient presenting with a recent MI who has a new systolic murmur should be thoroughly investigated for the presence of a VSR and thus the role of echocardiography in the evaluation of these patients is crucial in decreasing adverse patient outcomes. This rare presentation of an advanced age case, with heart failure, required urgent attention and immediate treatment due to the severity of the shunt from the VSR.

Take home message

• VSR is a rare and potentially fatal mechanical complication of acute transmural or ST segment MI.

• Rapid deterioration can occur in the acute phase of a VSR post-MI, thus prompt diagnosis for surgical planning is crucial for improving patient outcomes.

• TTE is a specific and sensitive imaging tool for investigation of the presence of a VSR.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethics Approval

This manuscript has been produced in accordance with ethical standards including written informed consent was obtained from the patient for publication of this case report and accompanying images.

Guarantor

NMA.

Contributors

NMA and AW researched literature and conceived the study. NMA was involved in gaining ethical approval, patient recruitment and provision of the diagnostic imaging. NMA wrote the first draft of the manuscript. Both authors reviewed and edited the manuscript and approved the final version of the manuscript.

ORCID iD

Natasha M Amorosi https://orcid.org/0000-0002-5802-1395