Asian Cardiovasc Thorac Ann 2008;16:401-406
© 2008 Asia Publishing EXchange Ltd
Ventricular Restoration by Linear Endoventricular Patchplasty and Linear Repair
V Rao Parachuri, FRCS,
Srilakshmi M Adhyapak, DNB,
Praveen Kumar, MCh,
Ravindra Setty, MCh,
Ravi Rathod, MCh,
Devi P Shetty, MS
Department of Cardiothoracic Surgery, Narayana Hrudayalaya, Bangalore, India
For reprint information contact: V Rao Parachuri, FRCS, Tel: 91 80 783 5000, Fax: 91 80 783 2648, Email: srili2881967{at}yahoo.com, Narayana Hrudayalaya, 258/A Bommasandra Industrial Area, Anekal Taluk, Bangalore 560099, India.
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ABSTRACT
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Surgical ventricular restoration improves cardiac function in patients with large left ventricular aneurysms. Aneurysm repair techniques have evolved to geometric repair by exclusion of the aneurysmal area with a circular patch. But even circular endoventricular patchplasty may result in a less elliptical ventricle. We modified the techniques of both linear and geometric repair. The early and intermediate outcomes in 102 patients with post-infarction left ventricular aneurysm, treated between 2001 and 2004, were analyzed. Concomitant procedures included coronary artery bypass grafting in 73 patients, mitral valve repair in 29, cryoablation in 3, and post-infarction ventricular septal rupture repair in 3. Overall mortality was 12.7%. Left ventricular ejection fraction increased significantly postoperatively, from 31.5% ± 6.5% to 34.2% ± 5.9%. There were significant decreases in end-diastolic volumes from 140.3 ± 38.3 to 100.8 ± 33.5 mL, and end-systolic volumes from 95.1 ± 26.1 to 66.0 ± 21.7 mL. These benefits continued at the 12- to 52-month follow-up. Our modified technique restores a near physiological left ventricular geometry and has a favorable clinical outcome.
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INTRODUCTION
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Surgical ventricular restoration (SVR) has been found to improve cardiac function and functional status in patients with post-infarction left ventricular (LV) aneurysm, compared to medical therapy alone.1 Initially, SVR was performed by excision of the aneurysmal area followed by linear repair.2 This technique left the scarred area of the septum undisturbed, and led to distortion of LV geometry. Techniques of geometric repair by endoventricular patchplasty addressed the infarcted septum, resulting in further reduction of LV volume and improved cardiac performance.3–5 Although endoventricular circular patchplasty is superior to linear repair, it still results in a ventricular shape that is more spherical than elliptical. There is incomplete exclusion of the infarcted zone due to the variable extent of its involvement (anterior wall and apex) from the base of the heart to the apex.6,7 We modified the endoaneurysmorrhaphy by utilizing a linear endoventricular patch, which addresses the infarcted zone from base to apex, instead of a circular patch that is mainly confined to the apex. Linear repair was performed at the ventriculotomy site to strengthen the endoventricular repair.
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PATIENTS AND METHODS
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Between 2001 and 2004, SVR was performed in 102 patients aged 25 to 75 years, with a mean age of 43.2 ± 8.3 years. There were 82 men and 20 women, of whom 60% were in New York Heart Association (NYHA) functional class IV. Inclusion criteria were previous transmural myocardial infarction (MI), significant LV dilatation with LV end-systolic volume index 
60 mL·m–2 with large akinetic or dyskinetic segments. Most patients (95%) presented with cardiac failure, of whom 28% also had angina; 5% presented with ventricular tachyarrhythmias. There was no incidence of thromboembolism. The location of the aneurysm was anterior due to anterior myocardial infarction (MI) in 95 patients and inferior in 7 with inferior MI. There were 65 patients with diabetes. Preoperative LV dimensions and volumes measured by echocardiography were: internal diameter in diastole, 60.2 ± 7.5 mm; internal diameter in systole, 48.1 ± 7.9 mm; end-diastolic volume index, 140.3 ± 38.3 mL·m–2; end-systolic volume index, 95.1 ± 26.1 mL·m–2; and ejection fraction (EF), 31.5% ± 6.5%. The sphericity index was 0.9 ± 0.02. Institutional review board approval was obtained to perform postoperative contrast ventriculography at 6 months and beyond, and informed consent was obtained from all patients. Contrast ventriculography revealed 61.1 ± 12.8 hypokinetic segments and 32.5 ± 11 akinetic or dyskinetic segments, quantified by the centerline method.8 Here, motion is measured along 100 chords drawn perpendicular to a line constructed midway between the end-diastolic and end-systolic contours on the left ventriculogram in 30° right anterior oblique projection. The measured motion of the 100 chords is normalized for heart size by dividing it by the length of the end-diastolic perimeter. As normal motion varies from chord to chord, the normalized motion at each chord is converted into units of normal standard deviations from the normal mean motion at each chord. Wall motion in each of 5 regions of the LV contour is determined by averaging the motion abnormality (expressed as standard deviation) of chords 1–16, 17–32, 33–48, 49–64 and 65–80, corresponding to the anterobasal, anterolateral, apical, inferior and posterobasal regions, respectively. The hypokinetic chords are negative and hyperkinetic chords are positive.
SURGICAL TECHNIQUE
A linear 8–12-cm LV incision was made parallel to the left anterior descending coronary artery, 2–3 cm lateral to it, from the base to the apex of the heart. No LV cavity measuring devices were used as we consider them inaccurate during cardioplegia; we relied instead on visual assessment of the residual LV cavity. For the same reason, we do not advocate plication of the border zone by Fontan suture, as this increases the sphericity of the ventricle. We used a linear patch described below (Figure 1
). A 3 x 10-cm linear Hemashield patch was sutured inside the LV cavity, starting from the base towards the apex, using 3/0 Prolene (Figure 2). The length of the patch was tailored to the extent of the infarct from base to apex, usually 6–10 cm. The patch was placed laterally anterior to the anterior papillary muscle. On the medial side, as much as possible of the infarcted septum was excluded without compromising the residual LV cavity. The patch lay obliquely, being molded to the LV cavity. Towards the apex, a neo-apex was created by excluding the aneurysmal apex. The ventriculotomy was closed using a linear repair in 2 layers, buttressed with a Teflon strip (Figure 3). Inferior wall aneurysms were repaired similarly, but the scar did not involve the septum. The LV was opened approximately 2-cm lateral to the posterior descending artery. The cavity was visually assessed to locate the posteromedial papillary muscle (generally spared from the aneurysm), and a linear Hemashield patch was sutured to the rim of non-infarcted tissue between the scarred aneurysm and the myocardium. This was followed by a Teflon-buttressed linear repair at the ventriculotomy site. Concomitant procedures included coronary artery bypass grafting in 73 (77.6%) patients, mitral valve repair for significant ( grade 2) regurgitation in 39 (41.4%), using Alfieri repair in 19 and a flexible annuloplasty ring in 20. Post-MI ventricular septal defect repair was also performed in 3 patients, and cryoablation for ventricular tachycardia or fibrillation in 3.
Follow-up ranged from 0 to 52 months, with mean follow up of 24 ± 6.1 months. Functional improvement according to NYHA class was obtained by follow-up visit, questionnaire, or telephone interview in 72 survivors.
STATISTICAL ANALYSIS
The Student t test was used to compare preoperative and postoperative continuous variables, which are expressed as mean ± standard deviation. The chi-squared test and Fischer’s exact test were used for analysis of categorical variables. Univariate regression analysis was used to determine factors associated with early hospital mortality and a low cardiac output state. Survival rates were estimated by the Kaplan-Meier method. All parameters and subgroups were compared using the log-rank test for analysis of possible influences on early and midterm survival. SPSS software version 10.0 for Windows (SPSS, Inc, Chicago, IL, USA) was used in data analysis. A value of p < 0.05 was considered significant.
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RESULTS
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Hospital mortality after SVR was 7.8% (8 patients). This included a patient with post-MI ventricular septal rupture who had been in low cardiac output with multiorgan failure preoperatively. Five patients who underwent concomitant mitral valve repair succumbed in the intensive care unit in the 2nd postoperative week; an intraaortic balloon pump was required in 3 of them. The other 2 patients died from multiorgan failure. Factors analyzed as predictors of early mortality are listed in Table 1. Major complications in the early postoperative period included intraaortic balloon pump use in 5 patients. It was inserted perioperatively in 2 due to low cardiac output, based on systolic blood pressure < 90 mm Hg, low cardiac index, and low urine output. A low cardiac output state developed in 56 (54.9%) patients, of whom 48 were discharged and 8 died. Renal dysfunction occurred in 4 patients, which was managed conservatively. There were no significant postoperative arrhythmias, and the incidence of postoperative infection was low (11%). Assessment of factors associated with postoperative low cardiac output state is summarized in Table 1. Ejection faction in 94 patients increased significantly from 31.5% ± 6.5% before SVR to 34.2% ± 5.9% before discharge from hospital. Left ventricular dimensions and volumes decreased significantly after SVR: Left ventricular internal dimension in diastole from 60.2 ± 7.5 to 55 ± 7 mm; LV internal dimension in systole from 48.1 ± 7.9 to 43.4 ± 7.7 mm (p < 0.001); end-diastolic volume index from 140.3 ± 38.3 to 100.8 ± 3.5 mL·m–2 (p < 0.001); and end-systolic volume index from 95.1 ± 26.1 to 66 ± 21.7 mL·m–2 (p < 0.001). The sphericity index at discharge was 0.79 ± 0.04 (p 0.05). No patient had an excessive reduction in LV volume resulting in diastolic dysfunction, assessed by Doppler echocardiography.
We followed up 72 patients over a period of 0 to 52 months; the other 22 were from outside the country and follow-up was not possible. Mean duration of follow-up was 24 ± 6.1 months. Echocardiography showed further significant reductions in LV dimensions and volumes (all p < 0.001): Left ventricular internal dimension in diastole from 55 ± 7 to 51.2 ± 6.6 mm; LV internal dimension in systole from 43.4 ± 7.7 to 38.4 ± 6.9 mm; end-diastolic volume index from 100.8 ± 33.5 to 68.4 ± 12.4 mL·m–2; and end-systolic volume index from 66 ± 21.7 to 54.2 ± 16.4 mL·m–2. There was a further improvement in EF from 34.2% ± 5.9% to 38.4% ± 4.5% ( p < 0.001). Sphericity index improved to 0.62 ± 0.02, which was significantly better than the preoperative value ( p < 0.01). We assessed 57 patients for LV geometry by contrast ventriculography 6 months after SVR. There was a decrease in hypokinetic segments from 61.1 ± 12.8 to 36.5 ± 14.8 chords, and a decrease in akinetic or dyskinetic segments from 32.5 ± 11 to 25 ± 8.1 chords. There were significant improvements in the anterobasal, anterolateral and posterobasal segments in anterior aneurysms, and in posterobasal and inferior segments in inferior aneurysms (Table 2), with further decreases in LV volumes and increases in EF from pre-discharge values, reflecting continuing negative LV remodeling. There were 5 midterm deaths at 8 ± 1.2 months after SVR, confirmed by telephone interview. Two patients suffered sudden cardiac death and 3 were hospitalized at local hospitals and died of cardiac causes.
Results of survival analysis are presented in Table 3. The functional capacity in the survivors improved to NYHA class I in 92% and to class II in 8%. Revascularization and mitral valve repair had no effect on early mortality or midterm survival, but they were associated with less frequent low cardiac output. Cardiac failure requiring hospitalization developed in 4 patients. The interval from SVR to development of cardiac failure was 9.2 ± 1.2 months.
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DISCUSSION
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Coronary artery disease in the South Asian population has shifted to a younger age at presentation.9 Following a transmural MI, despite successful early reperfusion therapy, ventricular aneurysms develop in 4% 20% of patients.10 The prognosis of ischemic cardiomyopathy is more closely related to LV volume than EF.11 The normal oblique myofiber orientation is altered to a more transverse axis, leading to increased sphericity and dilatation of the ventricle. Elliptical shape is an important determinant of LV function.
Surgical reduction of LV radius decreases wall stress, reduces myocardial oxygen consumption, and improves myocardial efficiency which is based on Laplace’s law. Surgical ventricular restoration has evolved from the 1950s when Likoff and Bailey performed the first aneurysm repair.12 The linear repair technique popularized by Mickleborough and colleagues2 addressed only the free LV wall where the exteriorized scar was resected.
There was distortion of LV geometry by the linear suture, and incomplete septal infarct exclusion. In addition, the LAD territory could not be revascularized effectively. The geometric repair technique involved more infarct exclusion with a circular patch.3–5 The results were superior to those of linear repair in terms of LV geometry and long-term clinical outcomes.13 However, endoventricular circular patchplasty results in a less elliptical shape, which might give rise to suboptimal hemodynamics and function. It does not allow exclusion of a large septal scar, which continues to be part of the neo-ventricular cavity, and the improvement in LV geometry is confined to apical aneurysms. Cooley and colleagues14 achieved better LV geometry and function with smaller oval patches. The reductions in end-diastolic and end-systolic volumes in our patients were significant, as were the increases in EF. Similar reductions by endoventricular circular patchplasty were documented by the RESTORE group.15
Di Donato and colleagues16,17 studied the effects of the Dor procedure on LV dimensions and shape 1 year after surgery. They found increased diastolic sphericity and a systolic shape that was more elliptical than its diastolic counterpart, with respect to preoperative values. The postoperative LV chamber in all patients was more spherical, as shown by the sphericity index and centerline analysis of postoperative ventriculograms. The centerline method revealed significant improvements in the posterobasal and inferior segments, but not in anterolateral and anterobasal segments. This group also demonstrated greater chamber sphericity with larger preoperative LV volumes and greater degrees of late mitral regurgitation. This subset of patients had poorer clinical outcomes. Our modified technique ensures a more physiological ellipsoid ventricle, as evidenced by the sphericity index and improvements in the anterobasal and anterolateral segments by centerline analysis on contrast ventriculography. Linear endoventricular patchplasty allows apposition of layers containing different myofiber natural scaffold of LV architectural form. Our patients had better clinical outcomes, verified by improvements in NYHA class, with only 4 patients requiring readmission for heart failure after SVR. Revascularization and mitral valve repair were associated with a lower incidence of low cardiac output, possibly due to increased viable myocardium and lower pulmonary pressures, but these concomitant procedures had no impact on midterm survival.
Several reports have documented improved hemodynamics acutely after SVR, with pressure-volume loops showing a leftward shift in end-systolic and end-diastolic pressure-volume relationships, akin to diastolic heart failure.18 This study was conducted immediately after surgery and needs to be validated by similar studies in the follow-up period. Tagged magnetic resonance imaging has demonstrated improved basal ventricular rotation after endoventricular circular patchplasty, with better ventricular filling and diastolic function. 19 However, apical rotation, which forms the crux of ventricular torsion for optimal ventricular ejection, is unaffected by endoventricular circular patchplasty. This is due to a spherical postoperative ventricle. An ellipsoid shape is a prerequisite for normal apical rotation. The elliptical shape with normal ventricular torsion (basal and apical rotations) is an important determinant of systolic function. Several gaps exist in the understanding of micro to macro LV architecture and function, which constitute obstacles to designing effective strategies for the treatment of heart failure. The centerpiece of surgical therapy for heart failure has been the application of Laplace’s law for reduction of wall stress through reduction of the ventricular radius of curvature. However, the final LV form attained is more that of a smaller sphere than an ellipse. Surgical techniques resulting in a more conical shape lead to a change in myofiber orientation, resulting in an anisotropic structure with normalized mechanical and hemodynamic function.
Left ventricular hemodynamics by pressure-volume loops with conductance catheter studies and ventricular torsion were not studied postoperatively in our series. Such studies would help validate our technique of SVR in terms of restoration of near normal LV form and function.
However, it was concluded that SVR by our modified technique of combined linear endoventricular patchplasty and linear repair is simple, easily reproducible, and provides stability to the ventricle. It reduces ventricular volume uniformly, and restores a more physiological ellipsoid geometry to post-MI LV aneurysms. Our data demonstrate low postoperative mortality, improved ventricular function with persistent negative remodeling, and a low rate of re-hospitalization for congestive heart failure.
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ABSTRACT
INTRODUCTION
