Surgical ventricular restoration in patients with postinfarction coronary artery disease: effectiveness on spontaneous and inducible ventricular tachycardia

Characterizing heart failure in the ventricular volume domain

Heart failure (HF) may be accompanied by considerable alterations of left ventricular (LV) volume, depending on the particular phenotype. Two major types of HF have been identified, although heterogeneity within each category may be considerable. All variants of HF show substantially elevated LV filling pressures, which tend to induce changes in LV size and shape. Yet, one type of HF is characterized by near-normal values for LV end-diastolic volume (EDV) and even a smaller end-systolic volume (ESV) than in matched groups of persons without cardiac disease. Furthermore, accumulating evidence indicates that, both in terms of shape and size, in men and women, the heart reacts differently to adaptive stimuli as well as to certain pharmacological interventions. Adjustments of ESV and EDV such as in HF patients are associated with (reverse) remodeling mechanisms. Therefore, it is logical to analyze HF subtypes in a graphical representation that relates ESV to EDV. Following this route, one may expect that the two major phenotypes of HF are identified as distinct entities localized in different areas of the LV volume domain. The precise coordinates of this position imply unique characteristics in terms of the actual operating point for LV volume regulation. Evidently, ejection fraction (EF; equal to 1 minus the ratio of ESV and EDV) carries little information within the LV volume representation. Thus far, classification of HF is based on information regarding EF combined with EDV. Our analysis shows that ESV in the two HF groups follows different patterns in dependency of EDV. This observation suggests that a superior HF classification system should primarily be founded on information embodied by ESV.

Cryoablation during left ventricular assist device implantation reduces postoperative ventricular tachyarrhythmias

BACKGROUND

The number of patients undergoing implantation of a HeartMate II left ventricular assist device (LVAD; Thoratec Corporation, Pleasanton, Calif) is rising. Ventricular tachyarrhythmia (VA) after placement of the device is common, especially among patients with preoperative VA. We sought to determine whether intraoperative cryoablation in select patients reduces the incidence of postoperative VA.

METHODS

From January 2009 through September 2010, 50 consecutive patients undergoing implantation of the HeartMate II LVAD were examined. Fourteen of these patients had recurrent preoperative VA. Of those patients with recurrent VA, half underwent intraoperative cryoablation (Cryo: n = 7) and half did not (NoCryo: n = 7). Intraoperatively, patients underwent localized epicardial and endocardial cryoablation via LVAD ventriculotomy. Cryothermal lesions were created to connect scar to fixed anatomic borders in the region of clinical VA. Demographics, risk factors, intraoperative features, and outcomes were analyzed to investigate the feasibility of cryoablation.

RESULTS

Thirty-day mortality remained low (n = 1, 2%) among all LVAD recipients. There were no differences in risk factors between groups except that preoperative inotropes were less prevalent in Cryo patients (P = .09). Compared with NoCryo, the Cryo group had significantly decreased postoperative resource use and complications (P < .05). Recurrent postoperative VA did not develop in any of the Cryo patients (P = .02).

CONCLUSIONS

Postoperative VA can be minimized by preoperative risk assessment and intraoperative treatment. Localized cryoablation in select patients offers promising early feasibility when performed during HeartMate II LVAD implantation. Further prospective analysis is required to investigate this novel approach.

Surgical ventricular restoration to reverse left ventricular remodeling

Heart failure is one of the major health care issues in the Western world. An increasing number of patients are affected, leading to a high rate of hospitalization and high costs. Even with administration of the best available medical treatment, mortality remains high. The increase in left ventricular volume after a myocardial infarction is a component of the remodeling process. Surgical Ventricular Restoration (SVR) has been introduced as an optional therapeutic strategy to reduce left ventricular volume and restore heart geometry. So far, it has been established that SVR improves cardiac function, clinical status, and survival in patients with ischemic, dilated cardiomyopathy and heart failure. Since its first description , SVR has been refined in an effort to standardize the procedure and to optimize the results. This review will discuss the rationale behind surgical reversal of LV remodeling, the SVR technique, its impact on cardiac function and survival, and future expectations.

Left ventricular restoration: how important is the surgical treatment of ischemic heart failure trial?

If the Surgical Treatment of Ischemic Heart Failure (STICH) trial demonstrates that surgical therapy is superior to medical therapy, early aggressive evaluation of coronary artery disease as a potentially correctable cause of new-onset heart failure would be the preferred strategy. This strategy could tremendously change the treatment of ischemic heart disease. Confirming the STICH revascularization hypothesis will dramatically increase the use of coronary artery bypass grafting among the millions of patients now being medically treated without evaluation for an ischemic cause.

Endoaneurysmorrhaphy and cryoablation for postinfarction left ventricular aneurysm with ventricular tachycardia

BACKGROUND

Early reperfusion in the acute phase of myocardial infarction and better medical treatment of consequent heart failure and tachyarrhythmia have decreased the incidence of massive myocardial infarction, left ventricular (LV) aneurysm and also postinfarction-sustained ventricular tachycardia (VT). However, for a number of patients, surgical ablation combined with aneurysm resection and myocardial revascularization remains a possible curative procedure. In this study, the efficacy of endoaneurysmorrhaphy and cryoablation was evaluated in patients with postinfarction LV aneurysm with VT.

METHODS

The medical records of 9 patients who underwent LV endoaneurysmorrhaphy and cryoablation for VT at Taipei Veterans General Hospital between January 1995 and August 2005 were reviewed retrospectively.

RESULTS

There were 8 men and 1 woman, with a mean age of 69.7 years (range, 52-77 years). Preoperative VT and LV aneurysm were found in all patients, who underwent extensive cryoablation at the transitional zone of scar and viable tissue without intraoperative mapping and LV remodeling with prosthetic patch. Associated procedure included coronary artery bypass grafting in 8 patients. During follow-up, no surgical or in hospital mortality were noted. There was 1 late sudden death at home 1.7 months after the operation. No recurrent VT was detected, and all patients showed improvement in New York Heart Association functional class (mean, 2.33 vs.1.67; p=0.025) and LV ejection fraction (mean, 26.3% vs.34.1%; p=0.021).

CONCLUSION

In patients suffering from postinfarction LV aneurysm complicated with VT, combining cryoablation and endoaneurysmorrhaphy offers good arrhythmia control and clinical outcome.

Beneficial Hemodynamic and Clinical Effects of Surgical Ventricular Restoration in Patients With Ischemic Dilated Cardiomyopathy

BACKGROUND

Surgical ventricular restoration is increasingly applied in patients with ischemic dilated cardiomyopathy. Previous studies show promising results with regard to survival and clinical outcome. However, a comprehensive midterm analysis of this approach on left ventricular (LV) and right ventricular function is not yet available. We investigated biventricular function and clinical status at 6-month follow-up.

METHODS

We investigated the effects of surgical ventricular restoration on clinical variables, LV volume, right ventricular reverse remodeling, LV dyssynchrony, tricuspid regurgitation, and pulmonary artery pressure in 21 patients with ischemic dilated cardiomyopathy (New York Heart Association class III or IV) who underwent surgical ventricular restoration and coronary artery bypass grafting. Additional surgery included mitral annuloplasty (n = 14) and tricuspid valve annuloplasty (n = 8). Clinical variables (New York Heart Association class, quality-of-life questionnaire, 6-minute hall-walk test) and echocardiographic variables were assessed at baseline and at 6 months.

RESULTS

At 6-month follow-up, all clinical variables were significantly improved. Left ventricular ejection fraction improved from 0.27 +/- 0.10 to 0.36 +/- 0.11 (p < 0.01), LV end-diastolic volume decreased from 248 +/- 78 mL to 152 +/- 50 mL (p < 0.001), and LV end-systolic volume decreased from 186 +/- 77 mL to 101 +/- 50 mL (p < 0.001). Left ventricular dyssynchrony decreased from 61 +/- 41 ms to 12 +/- 12 ms (p < 0.001). Right ventricular annular diameter decreased from 30 +/- 7 mm to 27 +/- 6 mm, right ventricular short-axis from 30 +/- 9 mm to 27 +/- 7 mm, and right ventricular long-axis from 90 +/- 7 mm to 79 +/- 10 mm (all p < 0.05). Finally, significant reductions in severity of tricuspid regurgitation (from 1.3 +/- 1.1 to 0.9 +/- 0.6; p = 0.001) and pulmonary artery pressure (42 +/- 11 mm Hg to 28 +/- 10 mm Hg; p = 0.015) were observed.

CONCLUSIONS

Surgical ventricular restoration resulted in improvement of clinical variables, significant LV volume reduction, and reduced LV dyssynchrony at 6-month follow-up. In addition, right ventricular reverse remodeling was noted with reductions in tricuspid regurgitation and pulmonary artery pressure.

A clinically relevant large-animal model for evaluation of tissue-engineered cardiac surgical patch materials

Extracellular matrix (ECM) scaffolds may be useful as a tissue engineering approach toward myocardial regeneration in the infarcted heart. An appropriate large-animal model for testing the utility of biologically derived ECM in this application is needed. The purpose of this study was to develop such a model for optimal procedural success during and after patch implantation surgery. Myocardial infarction (MI) was created by embolization of the diagonal artery (DA) branch of the left anterior descending coronary artery with collagen suspension. After 4 to 6 weeks, 14 pigs received patch implant (ECM or expanded polytetrafluoroethylene). Six pigs were infarcted in the first DA and seven pigs in the second DA. Electrophysiology study was performed within 3 days before surgery. During surgery, the size and location of the infarct were measured. Infarcted myocardium (1.5-cm diameter) was transmurally excised under partial cardiopulmonary bypass. Patches (3-cm diameter) were sutured to the endomyocardial defect. Four pigs died postoperatively. After 1 month, 10 pigs were euthanized and the locations of patches were examined. Success rate of patch implant in the second DA (85.7%) was higher than the first DA (50%) group. Infarct size in the second DA was smaller than in the first DA (4.6+/-1.2 vs. 10.8+/-2.4 cm(2), P<.05). The second DA was more anteriorly positioned, which enabled easier access from the midsternal thoracotomy. However, the first DA was more laterally located requiring more manipulation of the heart during surgery. Electrophysiology revealed no ventricular tachyarrhythmia in the second DA but 33.3% in the first DA group (P<.05). At necropsy, the endocardial position of the first DA-infarct patches was anteroapical, whereas the second DA-infarct patches were more basolateral and often involved the anterior papillary muscle. The success rate of patch implant was associated with infarction size and location, and may be related to arrhythmic substrate. Experimental MI created by the second DA embolization is a feasible model for investigation of tissue-engineered cardiac patch implantation. This large-animal model is also suitable for study of cell therapy via endocardial catheter-based approaches or open surgical methods.

Ventricular arrhythmias after LV remodelling: surgical ventricular restoration or ICD?

Ventricular arrhythmias cause ~50% of deaths in remodeled ventricles after myocardial infarction, and the Multicenter Automatic Defibrillator Implantation Trial (MADIT II) showed that the Implantable Cardioverter Defibrillator (ICD) saved lives in high risk coronary patients with advanced left ventricular dysfunction. We studied 382 patients with remodeled hearts by preoperative Ventricular stimulation (PVS) to evaluate surgical ventricular restoration (SVR) that excludes scar and lower ventricular volume alters the early and late arrhythmia process without ICD utilization.

METHODS

Clinical and hemodynamic results before and after SVR in post-infarction patients, are compared to contrast spontaneous and/or inducible ventricular tachycardia to patients without arrhythmias. Study arrhythmia groups included: Spontaneous in 87 patients with clinical documented ventricular arrhythmias and inducible or not inducible ventricular tachycardia: Inducible in 105 patients without clinical ventricular arrhythmias but PVS inducible ventricular tachycardia; and No arrhythmias in 190 patients without spontaneous or PVS inducible ventricular tachycardia.

RESULTS

Preoperative LV end systolic volume index helped define preoperative arrythmia potential: Spontaneous > 120/m(2), inducible > 100 ml/m(2), and none < 100ml/m(2). Overall operative mortality rate was 7.6% (29/382). Sudden cardiac death rate was 2.5% causing 18.7% of all deaths. Surgical management reduced inducible ventricular tachycardia, from 41% preoperatively (144/352) to 8% (26/307) at early study, and 8% (14/177) one year later. Cardiac mortality was low at 5-years and not different between groups, despite use of only one late ICD device.

CONCLUSIONS

Favorable electrical success rate and low mortality always included volume reduction to interrupt functional re-entry circuits, but also added endocardiectomy, cryoablation, CABG and mitral repair when needed. Overall SVR findings show volume and shape alteration limits ventricular arrhythmias that impair prognosis, and suggests ICD devices are not needed.

Surgical Ventricular Restoration: The RESTORE Group Experience

Congestive heart failure may be caused by late left ventricular (LV) dilation following anterior infarction. Early reperfusion prevents transmural necrosis, and makes the infarcted segment akinetic rather than dyskinetic. Surgical ventricular restoration (SVR) reduces LV volume and creates a more elliptical chamber by excluding scar in either akinetic or dyskinetic segments. The international RESTORE group applied SVR in a registry of 1198 post-infarction patients between 1998 and 2003. Early and late outcomes were examined and risk factors identified.Concomitant procedures included coronary artery bypass grafting in 95%, mitral valve repair in 22%, and mitral valve replacement in 1%. Overall 30-day mortality after SVR was 5.3% (8.7% with mitral repair vs. 4.0% without repair, p < .001) Perioperative mechanical support was uncommon (< 9%). Global systolic function improved postoperatively, as ejection fraction increased from 29.6 +/- 11.0% to 39.5 +/- 12.3% (p < .001) and left ventricular end systolic volume index decreased from 80.4 +/- 51.4 ml/m(2) to 56.6 +/- 34.3 ml/m(2) (p < .001). Overall 5-year survival was 68.6 +/- 2.8%, Logistic regression analysis identified EF < or = 30%, LVESVI > o = 80 ml/m(2), advanced NYHA functional class, and age > or =75 years as risk factors for death. Five-year freedom from hospital readmission for CHF was 78%. Preoperatively, 67% of patients were class III or IV, and postoperatively 85% were class I or II.SVR improves ventricular function and is highly effective therapy in the treatment of ischemic cardiomyopathy with excellent 5-year outcome.

Left ventricular reconstruction benefits patients with dilated ischemic cardiomyopathy

BACKGROUND

Since the preoperative left ventricular end-systolic volume index (LVESVI) of greater than 100 mL/m2 was demonstrated to be an independent predictor of long-term mortality following isolated coronary artery bypass grafting (CABG), LV reconstruction (LVR) has been concomitantly performed in patients with a dilated LV due to ischemic cardiomyopathy.

METHODS

We retrospectively assessed the ability of preoperative and intraoperative variables to affect the actuarial survival in 48 patients with a preoperative LV ejection fraction (EF) of less than 0.30 and a preoperative LVESVI of greater than 100 mL/m2. Mean preoperative LVEF was 0.22 +/- 0.07, and preoperative LVESVI was 121 +/- 28 mL/m2. Coronary artery bypass grafting was performed in all patients. Mean number of grafted vessels was 2.8. The LVR was concomitantly performed in 20 patients and mitral valve plasty in 11. Preoperative and intraoperative variables were exposed to univariate and multivariate analyses.

RESULTS

There were 3 hospital deaths and 17 late deaths during the follow-up period. Causes of deaths were pump failure (9), myocardial infarction (2), ventricular arrhythmia (4), cerebral infarction (2), and cancer (2). Cox's proportional hazards model identified LVR and renal failure as independent factors, which affected the actuarial survival with odds ratios of 0.28 and 3.64 (p < 0.05). The 5-year actuarial survival (Kaplan-Meier) was significantly greater following LVR (90% +/- 11%) compared to isolated CABG (53% +/- 17%).

CONCLUSIONS

Left ventricular reconstruction contributed to improve the actuarial survival in patients with dilated ischemic cardiomyopathy, which could not be achieved by isolated CABG. The LVR can be an alternative to heart transplantation for the treatment of ischemic cardiomyopathy.

Changes in left ventricular volume and predictors of cardiac events after endoventricular circular patch plasty

OBJECTIVE

The aim of this study was to identify predictors of cardiac events after endoventricular circular patch plasty (Dor operation) by analyzing our experience with Dor operation.

METHODS

Thirty patients with left ventricular aneurysm and/or ischemic cardiomyopathy who underwent Dor operation were included in this study. Hemodynamic and clinical results were analyzed, and the predictors of cardiac events were examined.

RESULTS

Hospital mortality was 3.3%. Postoperative clinical status and left ventricular (LV) function in all survivors significantly improved. The survival rates at 1, 3, and 5 years after operation were 93%, 89% and 89%. The corresponding cardiac event-free rates were 75%, 67% and 49%. Pre- and postoperative LV function and volume did not differ significantly between patients with or without cardiac events. However, the proportion of reduced end-diastolic volume index (EDVI) (preoperative EDVI-postoperative EDVI) to preoperative EDVI was significantly higher in patients with cardiac events than in cardiac event-free patients. Postoperative LV volume re-increased in the cases with cardiac events during follow-up. Cox regression analysis confirmed that preoperative clinical premature ventricular contraction and end-systolic volume index (ESVI), postoperative EDVI, ESVI, and ejection fraction were independent predictors of late cardiac events. There was a significant positive correlation between preoperative ESVI and postoperative EDVI.

CONCLUSION

Though LV function significantly improved after Dor operation, LV reconstruction with excessive reduction can cause restarting LV remodeling and increasing mortality and morbidity. Therefore, LV reconstruction of appropriate sizes and shapes, considering the function of residual myocardium, has a significant effect on prognosis. It is highly reasonable to expect that preoperative ESVI can predict the optimal size of reconstructed left ventricle.