Post-Infarct Ventricular Septal Defect

Authors:
Jay A. Patel¹, Zubair Hashmi¹

Affiliations:
¹Department of Cardiothoracic Surgery, Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia, USA

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Take Home Message

A post-infarct VSD is a rare post-MI complication that carries a high mortality and is best diagnosed through echocardiography. It is initially managed medically (reduction of the left-to-right shunt and maintenance of adequate cardiac output), with potential escalation to mechanical circulatory support and surgery. The keys to surgical management include careful myocardial protection, patch closure of the VSD by anchoring it to healthy tissue, addressing concomitant coronary artery disease if there is at-risk myocardium, and a tension-free patch closure of the VSD and ventriculotomy. 

Learning Objectives

• Understand the clinical presentation, diagnostic findings, and workup of a patient with a post-MI VSD
• Understand the initial medical management and indications to initiate mechanical circulatory support.
• Understand timing for surgical repair of a post-MI VSD
• Discuss the conduct and surgical management of a post-infarct VSD and concomitant coronary artery disease
• Understand the surgical approach for VSD repair using a patch technique

Main Content

Introduction:
In this YouTube consult series video, Dr. Zubair Hashmi and Dr. Jay Patel review the presentation, diagnosis, medical management, and surgical management of a post-infarct VSD.

Presentation:

• The incidence of a post-MI VSD is approximately 0.2%, usually occurring 5 days post-MI. 30-day mortality of a post-MI VSD is 46% with medical treatment alone and 41% with surgical treatment.
• 2/3 of post-MI VSDs are anterior VSDs (anterior/apical septum) caused by LAD occlusion, and 1/3 are posterior VSDs (inferobasal septum), most commonly caused by a dominant RCA occlusion. There is a much higher mortality with posterior VSDs compared to anterior VSDs (73% vs 30%).
• Patient has a history of coronary artery disease and recent myocardial infarction, presenting with delayed dyspnea, new holosystolic murmur, and possibly cardiogenic shock.

Diagnosis:

• The best diagnostic modality is echocardiography, which defines the VSD, shunt direction, and other concomitant pathology.
• Right heart catheterization defines filling pressures, atrial pressures, Qp/Qs, and oxygen saturation step-up. A Qp/Qs >2 and an oxygen saturation step-up greater than 9% from the right atrium to the pulmonary artery is considered a significant VSD.
• Review the recent left heart catheterization, or repeat it if available.

Pre-operative Management:

• Determine the patient’s operative risk. Initial measures are aimed at decreasing the left-to-right shunt and ensuring adequate cardiac output and end-organ perfusion. This is achieved by supporting with inotropes/vasopressors as needed and by trending lactate and mixed venous oxygen saturation.
• If the patient is refractory to medical management and has cardiogenic shock. Initial management involves an intra-aortic balloon pump to reduce afterload and decrease the left-to-right shunt through the VSD. If the patient is in fulminant cardiogenic shock, VA ECMO and surgical intervention should be considered immediately.
• Once on ECMO, operative intervention should be delayed, if possible, to allow the infarcted muscle to scar and to increase the chances of a successful repair.
• A percutaneous VSD closure can be offered to patients of prohibitive surgical risk, delayed presentations, or recurrent VSD after repair. Percutaneous closure is not recommended if there is friable tissue, a large VSD, or proximity to the papillary muscles/mitral valve. Early involvement and discussion with interventional cardiology are important for determining candidacy.

Surgical Management:

• Perform aortic and bi-caval cannulation. Myocardial protection with both antegrade and retrograde approaches should be performed to provide optimal protection.
• If there is significant multivessel coronary artery disease, these distal bypasses should be performed first, and additional cardioplegia should be given down the grafts.
• For LAD territory disease and an apical VSD/infarct, bypass is generally not performed, as the infarcted muscle is no longer viable and offers little benefit. If there is disease proximal to the infarcted myocardium/VSD that would benefit from bypass to enhance flow to at-risk myocardium, a LIMA-LAD bypass can be considered.
• An apical VSD can be approached through a ventriculotomy a few millimeters lateral to the LAD territory, and adjacent to the septum. Identify the VSD and patch close the VSD by taking wide bites of 3-0 Prolene through healthy tissue from the RV, through the septum, and through the patch. The ventriculotomy is then closed using 2-0 Prolene by incorporating the patch and closing the ventriculotomy with felt or CorMatrix strips buttressed on either side, or through patch closure, taking care to create a tension-free closure that does not tear through the ventricular muscle.

References

1. Brescia, A. A., Louis, C., Wilder, F. G., Mehaffey, J. H., Coyan, G. N., Mozer, A. B., & Turek, J. W. (2022). TSRA Review of Cardiothoracic Surgery (3rd ed.). Thoracic Surgery Residents Association.
2. Arnaoutakis G, Conte J. Repair of Postinfarct Ventricular Septal Defect: Anterior Apical Ventricular Septal Defect. OpTechTCS, 19(1):96-114 (2014). Doi: 10.1053/j.optechstcvs.2014.03.002