Ventricular septal rupture as a complication of subacute myocardial infarction

81-year woman was admitted to hospital after 20 hours of chest pain for subacute Q-wave myocardial infarction (MI) of the anterior wall. Cardiac catheterization revealed significant stenosis of distal left main coronary artery (LMCA) and severe stenosis of left anterior descending (LAD) artery. PCI with drug eluting stents implantation of LMCA/LAD was performed with TIMI II flow at the end of the procedure.

Video 1 Angiography of the left coronary artery

Echocardiography showed systolic dysfunction of the left ventricle (EF 30-35%) with aneurysm of the anterior wall and the apex.

Video 2 Transthoracic echocardiography on admission

Day 3 - Paroxysm of atrial fibrillation with fast ventricular response observed. After continuous infusion of amiodarone was started, arrhythmia terminated.

Day 7 – New systolic murmur on ward rounds was documented. A repeated echocardiography revealed an apical ventricular septal rupture (VSR) (6-9 mm) with significant left-to-right shunt. 

Video 3 Transthoracic echocardiography showing apical ventricular septal rupture 

Day 9 – another paroxysm of atrial fibrillation with rapid ventricular response. Electric cardioversion to sinus rhythm was performed. 

Figure 1 Atrial fibrillation with rapid ventricular response (signs of LV aneurysm in anterolateral leads)

Despite cardioversion of atrial fibrillation was performed, organ functions were continuously worsening because of left heart failure. Therefore we decided for Intra-aortic balloon pump insertion as a haemodynamic support. Patient was also indicated for surgical management of ventricular septal defect.

Figure 2  Intra-aortic balloon pump on X-ray (radio-opaque marker approx. 1 cm above carina)
Patient got stabilized on IABP and on 19th in-hospital day, successful surgical repair of ventricular septal defect and LV aneurysm was performed. 

Transthoracic echocardiography after surgery showed non-dilated LV (EF 45%), LV apex and 2/5 of the apical anterior wall were akinetic. No septal defect was present, as well as no residual shunt to RV was documented.

Video 4 TTE after surgery

On the 33rd day after admission the patient was discharged in a stable condition.

Clinical context

Ventricular septal rupture is a rare (only 0.17 and 0.31% of patients with AMI), but lethal mechanical complication of acute myocardial infarction. Implementation of PCI into standard therapeutic management of ACS has led to a decline in the incidence of VSR, but despite that, overall mortality of patients who develop VSR remains high (41-80%). 

Ventricular septal defect usually occurs 3-5 days after AMI, but can occur much sooner in a matter of hours (median at 16 h). Risk factors for VSR include older age, female sex, prior stroke, chronic kidney disease, and CHF. 

Upon clinical presentation, VSR is more likely to develop in patients with ST segment elevation, initial positive cardiac biomarkers, cardiogenic shock, cardiac arrest, higher Killip class, and longer times to first balloon inflation or thrombolytic administration.

Rupture can occur at any anatomic location of the septum after a transmural infarction. Anterior infarctions are more likely to cause apical defects and inferior or lateral infarctions are more likely to cause basal defects at the junction of the septum and the posterior wall. This communication results in left to right shunting of oxygenated blood.

Clinical presentation

Every patient with AMI should be examined for mechanical complications. The easiest way is to listen for a characteristic harsh, holo-systolic murmur over the precordium. The symptoms may vary from complete hemodynamic stability to circulatory collapse depending on the size of the defect.

Management 

Afterload reduction is the foundation of acute treatment of VSR.  By reducing left-to-right shunting, the effective LV stroke volume increases. Vasodilators, such as intravenous nitroglycerin, in a combination with mechanical afterload reduction by intra-aortic balloon pump counterpulsation (IABP) may be considered routine care, even for hemodynamically stable patients to prevent often unexpected and fatal hemodynamic deterioration. Other options to stabilize the patient until surgery may be extracorporeal membrane oxygenation systems or left-ventricular assist devices as a bridge to surgery or transplant.

IABP – consist of a flexible catheter with a closed balloon, which can be periodically inflated in the aorta with helium gas. By inflating during diastole, it displaces blood volume from the thoracic aorta. In systole, as the balloon rapidly deflates, this creates a dead space, effectively reducing afterload for myocardial ejection and improving forward flow from the left ventricle. The effect is to decrease systolic aortic pressure by as much and increase diastolic pressure. Thanks to that, cardiac output, ejection fraction, and coronary perfusion are increased, with a concomitant decrease in left ventricular (LV) wall stress, systemic resistance to LV ejection, and pulmonary capillary wedge pressure.

Learning points

1) Always be aware of possible subacute myocardial infarction complications, such as VSR in our case, other complications include:
- Cardiogenic shock
- Ventricular aneurysm
- Thrombus formation
- Ventricular arrhythmias
- Free wall rupture‍

2) What are the VSR management possibilities?

  a) Surgery
     - Definitive surgery remains the treatment of choice, but is still a challenging operation associated.         with high early mortality (around 42%). Acute infarcted myocardium is weak and friable, and.         sutures hold poorly which leads to an increased risk of tearing and recurrent septal defects. For the.         repair to be successful, the surgeon must perform a debridement of infarcted tissue back to healthy.         myocardium (even if it involves enlarging the defect), and avoiding tension on the repair by using an.         appropriately sized patch. 

      The time between VSR detection and its repair is a determining factor in the survival or mortality of.        patients. Studies showed that earlier repair and operation in VSR patients increases the risk of.        mortality.

     A delayed surgery (usually > 2-3 weeks), should be preferred, because of improved stability of the.       cardiac tissue as the infarct evolves, allowing a more effective repair. Unfortunately, in a large.       number of patients, it is not possible to delay the operation since they are at risk of severe heart.       failure and organ dysfunction.  

 b) Percutaneous VSR closure
       - Percutaneous closure of VSR is an option for patients with significant risk for surgical repair, either.           as a definitive strategy, or as a bridge to surgery after initial stabilization. For this to be successful.           the rupture must have favourable anatomy and an adequate tissue rim to secure the device. 

3) IABP can be used as a treatment strategy for off-loading of a left ventricle in patients with ventricular septal defect. Position of IABP should be checked on X-ray on a regular basis, as distal migration of the device might be observed.

What is the correct position of IABP on chest X-ray?

• The balloon should be located in the proximal descending aorta, just below the origin of the left subclavian artery. On CXR it should be at the level of the AP window. This ideally results in the balloon terminating just above the splanchnic vessels.
• TIP ! - Radio-opaque marker of IABP should be at 2 cm above the carina provided an adequate position for the IABP tip (1.5–3.5 cm distal to the origin of the left subclavian artery) 

References

1. Brandon M. Jones, Samir R. Kapadia, Nicholas G. Smedira, Michael Robich, E. Murat Tuzcu, Venu Menon, Amar Krishnaswamy, Ventricular septal rupture complicating acute myocardial infarction: a contemporary review, European Heart Journal, Volume 35, Issue 31, 14 August 2014, Pages 2060–2068, https://doi.org/10.1093/eurheartj/ehu248
2. Urschel CW, Eber L, Forrester J, Matloff J, Carpenter R, Sonnenblick E. Alteration of mechanical performance of the ventricle by intraaortic balloon counterpulsation. Am J Cardiol. 1970 May;25(5):546-51. doi: 10.1016/0002-9149(70)90593-x. PMID: 5441342.
3. Intra-aortic Balloon Counterpulsation: Overview, Indications, Contraindications. Diseases & Conditions - Medscape Reference [online]. Accessible at: https://emedicine.medscape.com/article/1847715-overview
4. Shafiei I, Jannati F, Jannati M. Optimal Time Repair of Ventricular Septal Rupture Post Myocardial Infarction. J Saudi Heart Assoc. 2020 Jul 31;32(2):288-294. doi: 10.37616/2212-5043.1120. PMID: 33154931; PMCID: PMC7640570.
5. Mubarik A, Iqbal AM. Ventricular Septal Rupture. 2020 Apr 14. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–. PMID: 30521278.

Authors: Michal Pazderník, Lucie Mayerová