Post MI Ventricular Septal Defects

Nick Tehrani, MD

Overview

VSD Complicates 1-2% of cases of acute myocardial infarction.First successful correction reported by Cooley in 1957.

Overview

High mortality despite various improvements in therapy

30 day mortality- 74%1 year mortality- 78%

GUSTO analysis, Crenshaw et al,

Circ. 1/2000

Overview

Relative Improvement in survival due to

Earlier diagnosisEarlier flow restoration More aggressive surgical intervention

Overview

Incidence declining due to:

Earlier restoration of flow, preventing transmural MIMore aggressive BP control post MI

Overview

Predictors of VSDAdvanced age,Anterior location of infarction,Female sex,No history of smoking

Per GUSTO analysis

Thrombolysis after 12 hours also suggested as a predisposing factor.

Overview

Average time to rupture2-4 days

Range: few hours 2 weeks

Time course may be accelerated by thrombolysis, possible related to intramyocardial hemorrhage

Overview

Coronary anatomy and VSD

Post MI VSDs more commonly associated with 100% occlusion of the infarct related arteryThis was observed in all of our patients

Anatomy of VSDs

Two types of VSD

Simple: through and through defect usually located anteriorlyComplex: serpentiginous dissection tract remote from the primary septal defect- most commonly an inferior VSD

Patient BG had such a presentation

Transesophageal Echocardiogram of Complex VSD

Angiography

Anatomy of VSDs

Antro-apical septal rupture

Comprise approximately 60-80% of casesLAD occlusion is always the culprit

Anatomy of VSDs

Posterior septal ruptureApproximately 20-40% of casesOcclusion of

Dominant RCA => extensive RV infarctionDominant LCX (Less common), RV mostly spared

Anatomy of VSDs

Multiple defects (5-11% of cases)

Secondary to infarct extensionEvolve within days of each other

Anatomy of VSDs

Our series

Antro-apical septumThree of four cases

Posterior septum One of four cases

Pathophysiology

Antero-apical septal rupture

TamponadeSecondary RV failiure due to acute volume overload

Pathophysiology

Posterior septal ruptureCommonly complicated by MRShunt reversal due to elevated RVEDP

Diagnosis

Loud/harsh pansystolic murmur

Within the first week post AMIBest heard at Lt. Lower sternal borderLess loud at the apexAssociated with a palpable thrillDepending on the location, may radiate to the axilla mimicking MR

Diagnosis

Up to 50% of patients experience chest pain associated with the development of murmur

CHF and shock often associated with the development of murmur

Diagnosis

Color Flow Doppler

100% sensitive and specific in differentiating VSD from acute MRSite of septal rupture correctly identified in 41 of 42 patientsOne of our 4 patients had had a negative TTE earlier in the day, and no apparent homodynamic changes prior to the catheterization later that day

Smyllie et. Al. 1990 JACC

Diagnosis

Earlier diagnosis and surgical intervention, may be due to greater availability of Echocardiography at peripheral centers.

Diagnosis

Need for cardiac catheterization2/3 of the patients have multivessel coronary artery diseaseDecreased operative mortality and improved late survival has been shown in patients with multivessel diseaseCardiogenic shock not a deterrent to Cath

=> Coronary angiography should be performed

Diagnosis

Pre-Operative Management

Hemodynamic stabilization so as to minimize peripheral organ compromise

Reduce Systemic vascular resistance, and thus, the left-to-right shuntMaintain or improve coronary artery blood flowMaintain cardiac output and arterial pressure to ensure peripheral organ perfusion

=> IABP

Timing of Surgery

Controversial (in the past)Non-randomized studies showing:

Early repair, 40% - 50% mortalityLate repair (past 3 weeks), 10% mortality

=>

Aggressive Medical management aimed at delaying surgical intervention

Timing of Surgery

Short-coming of the argumentPatients with less sever hemodynamic compromise, more likely to survive the acute phase without need for prompt

surgery:

Lower pre-op risk =>Better outcome

Timing of Surgery

Short-coming of the argumentPatients with greater hemodynamic compromise, and more severe insult:

Higher pre-op risk =>Worse outcome

Timing of Surgery

Surgery should be performed soon after diagnosis in most patientsPatients is cardiogenic shock should be operated on immediately after anigographyHemodynamically stable patients should have surgery on an urgent basis

Operative Technique

Classical approach to antero-septal rupture

Infarctectomy, andReconstruction of the ventricular septum with Dacron patches

Operative Technique

Classical approach to infro-posterior rupture

Infarctectomy, andReconstruction of infroposterior VSD,

ReconstructionReconstruction free wall with Dacron patches.

Outcome

In a review of 139 cases reported in the literature prior to 1977

Six month survival without surgical intervention was less than 10%.

Kirklin, Churchill Livingston 1993

Outcome

Predictors of early mortality per multivariable logistic regression analysis in a series of 22 patients

DMElevated RA pressure (RV involvement/IMI)Absence of intraoperative IABP

Outcome

Predictors of early mortality per GUSTO analysis

Advanced ageInferior location of MI

Outcome

In patients with cardiogenic shock mortality reported to be the highest

Posterior VSD (IMI) is another factor strongly associated with poor surgical outcome due to

Difficulty of exposure, and Frequent concomitant infarction of the postero-medial papillary muscle

Compilation from 6 series from the late 80s

Outcome

David, in a series of 44 patients reported no difference between mortality rates for the posterior and anterior VSD using the

Exclusion technique

Exclusion Technique

Exclusion techniqueLV excluded from the infarcted muscle using a bovine pericardial patch sutured to the healthy peri-infarct endocardiumNo infarctectomy is performed RV is undisturbed

Better RV function preservationMay help support the posteromedial papillary muscle

Exclusion technique

Exclusion technique

Outcome

Residual Lt. Rt. shunt

Reported in up to 28% of survivorsAssociated with high mortalityIntra-operative TEE useful in early detection and correction if deemed necessarySeen in one of our patients.

Patient was treated medically

Residual VSD

Post-Op state

DialysisCommonly required in patients in shockNot required by either of our two survivors

Prolonged ventilatory supportResidual or recurrent VSD

Reoperation may be necessary depending on the shunt size and hemodynamics

Clinical Profile of our Patients