STS E Book - Surgical Treatment of Mechanical Complications of MI Flashcards
Ventricular septal rupture leading to VSD in the setting of MI occurs in what percentage of acute MI?
0.17% - 0.34%.
What is the mortality of VSR after MI when treated medically?
Almost uniformly fatal.
24% in the first 24 hours, 46% at 1 week, and 67% to 82% at 2 months.
What is the mortality of VSR after MI with optimal treatment including surgical correction?
19% - 54%.
What is the timing for rupture of the ventricular septum following MI? What is the reason for this timing?
*2 timelines
1-2 days - infarct-associated intramural hematoma leading to dissection within the septal wall that ruptures.
3-5 days - coagulation necrosis mediated by neutrophils -> apoptosis -> lytic enzyme release -> erosion and rupture
Where do VSRs after MI typically occur? Where is the perfusion distribution from?
*2 places
Anterior - after LAD injury
Inferoposterior - RCA
Compare posterior to anterior ventricular septal rupture after MI - complexity, mortality, reason for mortality difference.
Ruptures that occur posteriorly tend to be more complex, with septal defects occurring through serpiginous tracts, wherein the septal entry point in the left ventricle is not directly across from the corresponding defect in the right ventricular septal wall.
This is in contrast to anterior septal infarctions, which tend to be apical and simple, that is, a discrete defect with a direct communication through the septum.
The location of the rupture is significant because multiple studies have demonstrated a significantly increased mortality with ruptures in the posterior portion of the septum.
This increased mortality appears to be associated with right ventricular infarction and subsequent right heart failure.
Describe the pathophysiology of hemodynamic decompensation in VSR after MI.
A left-to-right shunt is created with a VSR, which rapidly leads to right ventricular volume overload and failure. This, in turn, leads to increased blood flow through the pulmonary circulation, with subsequent secondary volume overload of the left heart. As the left heart begins to fail, systemic vascular resistance increases to maintain afterload, which then increases the magnitude of the left-to-right shunt until the left heart fails to the point that it cannot maintain systolic pressure, and left-to-right shunting declines.
Comment on the data for early surgery (within 7 days) for VSR after MI. What is the admitted bias?
Increased mortality with shorter intervals between VSR and surgery.
Survival bias. The patients operated on within 7 days are those without other options.
What’s the ideal method to diagnose VSD? What do you see on this study?
TTE. Color Doppler shows flow across the septum. 2-D imaging of the 4-chamber view shows a drop-out of signal.
What is the best way to medically manage VSD after MI (before surgery)?
Goals are to prevent cardiogenic shock and reduce L to R shunting.
IABP. Vasodilators. Diuretics. Inotropes.
Stabilize the patient before taking them to the OR.
What is the operative mortality for VSD after MI?
31% to 65%
Describe the Daggett repair of VSR after MI?
Infarctectomy with wide excision of the infarcted tissue and closure of the septal defect and the ventriculotomy with prosthetic patches. Variations include a single-patch technique in which the septal defect and the ventriculotomy are closed with a single patch or multiple patches in several layers with fibrin glue.
Describe the David repair of VSR after MI?
David repair of ventricular septal rupture involves exclusion of the infarcted myocardial muscle and ventricular septal defect with an endocardial patch.
Compare David and Daggett VSD repair outcomes.
Retrospective comparison of the techniques demonstrated five-year survival of 67% with the David technique and 48% with the Daggett technique.
For VSR repair after MI (either David or Daggett), is it preferable to approach from the LV or RV?
Left ventricular approaches are preferred to right ventricular approaches, as the trabeculations within the right ventricle make visualization and accurate repairs of the defect more challenging.
