Robotic and endoscopic mitral valve repair for degenerative disease

BACKGROUND

Minimally invasive mitral valve repair has been proven to be a safe alternative to open sternotomy and may be accomplished through classic endoscopic and robotic endoscopic approaches. Outcomes across different minimally invasive techniques have been insufficiently described. We compare early and late clinical outcomes across matched patients undergoing robotic endoscopic and classic endoscopic repair.

METHODS

From 2011 to 2020, 786 patients underwent minimally invasive mitral surgery, from which we were able to generate 124 matched patients (62 patients in each cohort). Clinical results were then compared between the two matched populations. Survival analysis was used to compare freedom from mortality to 10 years among matched classic endoscopic and robotic endoscopic mitral valve repair cohorts and to calculate freedom from moderate or severe mitral insufficiency at latest follow-up. Histograms of cardiopulmonary bypass (CPB) and aortic cross-clamp times were constructed, and mean bypass and cross-clamp times were compared between classic endoscopic and robotic endoscopic cohorts.

RESULTS

There was no difference in early or late mortality at 10 years in either cohort. Freedom from moderate or severe mitral regurgitation or mitral valve replacement at last echocardiogram was 86.4% vs. 73.5% at 10 years, P=0.97. Patients undergoing robotic endoscopic mitral repair had a significantly longer CPB run when compared to the classic endoscopic cohort, with 148 min of CPB in the robotic endoscopic cohort compared to 133 min in the classic endoscopic group, P=0.03. Overall post-operative length of stay was not statistically significant between the robotic endoscopic and classic endoscopic groups, 6.3±0.5 and 6.0±0.3 days, respectively. No patients in either cohort developed renal failure or wound infection. The classic endoscopic group had a slightly higher risk of prolonged ventilation when compared to the robotic endoscopic group, with three classic endoscopic patients remaining intubated >8 hours post-operatively, compared to a single patient in the robotic endoscopic group. There were no unplanned reoperations in either group. Rates of postoperative stroke were comparable between groups (three in the classic endoscopic cohort, and two in the robotic endoscopic cohort).

CONCLUSIONS

Index mitral valve surgery via a classic endoscopic approach yields similar clinical outcomes when compared to robotic endoscopic surgery. We demonstrate that both classic endoscopic and robotic endoscopic approaches allow repair of degenerative mitral valves with excellent short- and medium-term outcomes in a tertiary referral center.

Permanent pacemaker implantation following mitral valve surgery: a retrospective cohort study of risk factors and long-term outcomes

OBJECTIVES

Conduction disturbances requiring permanent pacemaker (PPM) implantation remain a complication following valvular surgery. PPMs confer the risk of infection, tricuspid valve regurgitation and pacing-induced cardiomyopathy. Literature examining PPM placement in mitral valve surgery (MVS) is limited.

METHODS

Our institutional mitral valve (MV) database was retrospectively reviewed for adult patients undergoing surgery from 2011 to 2019. Patients with preoperative PPM were excluded. Patients were stratified by the receipt of PPM following their index operations. Multivariable logistic regression was performed to determine patient and operative risk factors for PPM. Subgroup analysis was performed on patients who underwent isolated MVS. Kaplan-Meier analysis and a multivariable Cox proportional hazards model were utilized to assess the association between PPM implantation and long-term survival.

RESULTS

A total of 3391 (2991 non-PPM and 400 PPM) patients met the study criteria. Significant predictors of PPM included increased decade of age (odds ratio: 1.23; 95% confidence interval: 1.12-1.35), concomitant aortic (1.44; 1.10-1.90) and tricuspid valve procedures (2.21; 1.64-2.97) and prior history of myocardial infarction (1.48; 1.07-1.86). In the isolated MV repair population, annuloplasty with ring prosthesis was associated with PPM (3.09; 1.19-8.02). Patients in the replacement population did not have significant identifiable risk factors. There was no survival difference found, and postoperative PPM placement was not found to be an independent predictor of mortality.

CONCLUSIONS

Our primary aim was to elucidate predictors for PPM implantation in MVS and found increasing age and concomitant procedures to be risk factors. Receipt of PPM is associated with worse long-term survival but does not independently predict survival. Among patients undergoing isolated MV repair, use of an annuloplasty ring confers a higher risk of PPM compared to an annuloplasty band.

Repair of Isolated Native Mitral Valve Endocarditis: A Propensity Matched Study

In the setting of chronic primary mitral regurgitation, the benefit of mitral valve repair over replacement is well established. However, data comparing outcomes for mitral valve surgery for endocarditis is limited. We sought to determine whether mitral valve repair offers traditional advantages over replacement in the endocarditis population. Retrospective review of our institutional mitral valve database (N = 8,181) was performed between 1998 and 2019 for all adult patients undergoing isolated mitral valve surgery for endocarditis. Patients were stratified by mitral valve repair or replacement and propensity score matching was performed to adjust for differences in baseline characteristics and degree of valve damage. Overall, 267 surgeries (124 repair, 153 replacement) met inclusion criteria during the study period. Following propensity matching, the repair cohort was associated with shorter initial ventilator times (5.6 vs 7.9 hours, p = 0.05), shorter ICU (28 vs 52 hours, p = 0.03), and hospital lengths of stays (7 vs 11 days, p < 0.01). Thirty-day mortality (0% vs 2.1%, p = 0.01) and 10-year survival (88% vs 86%, p = 0.55) were similar between cohorts. Patients in the repair cohort were less likely to require repeat mitral valve intervention at our institution for recurrent endocarditis than those in the replacement cohort (0% vs 10.6%, p = 0.03). Mitral valve repair is safe, when feasible, in the setting of isolated native valve endocarditis and may provide patients faster recovery. Experienced mitral surgeons should approach this patient population with a "repair if feasible" methodology.

Operative Outcomes of Concomitant Minimally Invasive Mitral and Tricuspid Valve Surgery

Objective

The aim of this study was to evaluate whether the addition of concomitant tricuspid valve surgery (TVS) negatively impacted operative outcomes of minimally invasive mitral valve surgery (MIMVS).

Methods

Patients undergoing MIMVS via a port-access right minithoracotomy between 2002 and 2014 at a single institution were reviewed. Patients were primarily stratified by those undergoing isolated MIMVS versus MIMVS+TVS. Propensity-matched cohorts were generated. Operative outcomes were compared between the propensity-matched cohorts and included operative mortality, complications, and length of hospital stay.

Results

A total of 1,158 patients underwent MIMVS via port-access right minithoracotomy. The majority of cases were elective (93%; n = 1,071) and 148 (13%) underwent concomitant MIMVS + TVS. Patients undergoing MIMVS + TVS were at higher risk at baseline. After propensity-matching, there were 119 isolated MIMVS and 119 MIMVS + TVS patients that were well matched with respect to all baseline variables. Cardiopulmonary bypass (148 ± 54 minutes versus 175 ± 54 minutes, P < 0.001) and aortic occlusion times (105 ± 36 minutes versus 128 ± 40 minutes, P < 0.001) were longer in the MIMVS + TVS group. Operative mortality was comparable (3% isolated MIMVS versus 4% for MIMVS + TVS; P = 0.73). Permanent pacemakers were required less frequently in the isolated MIMVS group (1% versus 6%; P = 0.03). All other complication rates were similar. Median length of hospital stay (7 versus 8 days; P = 0.13) and discharge-to-home rates (89% versus 94%; P = 0.15) were comparable.

Conclusions

Despite longer operative times, minimally invasive TVS performed concomitantly with MIMVS has similar operative outcomes with the exception of a higher pacemaker rate when compared with isolated MIMVS.

Minimally Invasive Mitral Valve Surgery III: Training and Robotic-Assisted Approaches

Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program.

Abstract 064: Improving Aortic Valve Replacement Risk Prediction: The Role of Geographically Derived Socioeconomic Factors

Objective: Low socioeconomic status (SES) is associated with worse surgical outcomes. Current risk adjustment models for aortic valve replacement (AVR) surgery do not include (SES), and therefore centers that treat large numbers of low-SES patients may be disadvantaged in hospital outcomes comparisons. This study evaluates whether inclusion of SES improves AVR risk prediction models.

Methods: All patients undergoing isolated aortic valve replacement (AVR) at a single institution from 2005-2015 were evaluated. We estimated patients’ SES using census-tract-level data, which are more precise than ZIP-code-level data. We excluded patients (~5%) with addresses that could not be geolocated to census tracts. SES covariates were available for 95% of the study population. SES measures included mean rates of unemployment, poverty, household income, home value, educational attainment, and housing density. The risk scores for mortality, complications and increased length of stay were generated using models published by the Society for Thoracic Surgeons. Univariate models were fitted for each SE covariate with a cut-off of p <0.2 for inclusion in the multivariable models for (a) mortality, (b) any complication, and (c) prolonged length of stay (PLOS) in addition to the expected risk. We evaluated the incremental value of SES covariates using area under the curve (AUC).

Results: Amongst the 1,386 patients undergoing AVR included in the study, the overall mortality was 2.8%, any complication rate was 15.1% and PLOS was 9.7%. In univariate models, higher education quartile was associated with decreased mortality (OR 0.96, p = 0.04) and complications (OR 0.97, p <0.01). Poverty was associated with increased length of stay (LOS) (OR 1.02, p =0.02). In the multivariable models, the inclusion of SES covariates increased the area under the curve (AUC) for mortality (0.735 to 0.750, p=0.14), for any complications (0.663 to 0.680, p<0.01), and for PLOS (0.749 to 0.751, p=.12)

Conclusions: The inclusion of census-tract-level socioeconomic factors into the STS risk predication models is new and shows potential to improve risk prediction for outcomes following AVR, particularly for predictions of any complications following AVR. With the possibility of reimbursement and institutional ranking based on these outcomes, this study represents an improvement in risk predication model even when limited to census tracts and a single institution’s experience.

The Impact of Deep Versus Moderate Hypothermia on Postoperative Kidney Function After Elective Aortic Hemiarch Repair

BACKGROUND

There remains concern that moderate hypothermic circulatory arrest (MHCA) with antegrade cerebral perfusion (ACP) may provide suboptimal distal organ protection compared with deep hypothermic circulatory arrest (DHCA) with retrograde cerebral perfusion (RCP). We compared postoperative acute kidney injury (AKI) in in patients who underwent elective hemiarch repair with either DHCA/RCP or MHCA/ACP.

METHODS

This was a retrospective review of all patients undergoing elective aortic hemiarch reconstruction for aneurysmal disease between 2009 and 2014. Patients were stratified according to the use of DHCA/RCP versus MHCA/ACP. The primary outcome was the occurrence of AKI at 48 hours, as defined by the Risk, Injury, Failure, Loss, End-Stage (RIFLE ) criteria. A multivariable logistic regression identified risk factors for AKI.

RESULTS

One hundred eighteen patients who underwent ACP and 471 patients who underwent RCP were included. The mean lowest temperature was 26.4°C in patients who underwent MHCA/ACP and 17.5°C in patients who underwent DHCA/RCP. Baseline demographics were similar except that patients who underwent DHCA/RCP were more likely to have peripheral arterial disease or bicuspid aortic valves. Cardiopulmonary bypass and aortic cross-clamp times were shorter in the MHCA/ACP group. AKI occurred in 19 (16.2%) patients who underwent MHCA/ACP and 67 (14.3%) patients who underwent DHCA/RCP. Four (0.8%) patients who underwent DHCA/RCP required postoperative dialysis. In-hospital mortality tended to increase with increasing RIFLE classification (RIFLE class-0 (No AKI) = 0.41%; Risk = 1.35%, and Injury = 10.0%; p = 0.09). On multivariable analysis, the lowest temperature and cerebral perfusion strategy were not significant predictors of AKI. Lower baseline glomerular filtration rate (GFR), lower preoperative ejection fraction, and longer cardiopulmonary bypass (CPB) time were independently associated with higher AKI.

CONCLUSIONS

We applied the sensitive RIFLE criteria to examine AKI in patients undergoing elective aortic hemiarch replacement for aneurysmal disease. Baseline renal dysfunction, lower ejection fraction, and longer CPB time are independent predictors of AKI. Compared with DHCA/RCP, our data suggest that an MHCA/ACP cerebral protection strategy does not appear to be associated with worse postoperative renal outcomes.

Minimally invasive mitral valve surgery is associated with equivalent cost and shorter hospital stay when compared with traditional sternotomy

OBJECTIVE

Mitral valve surgery is increasingly performed through minimally invasive approaches. There are limited data regarding the cost of minimally invasive mitral valve surgery. Moreover, there are no data on the specific costs associated with mitral valve surgery. We undertook this study to compare the costs (total and subcomponent) of minimally invasive mitral valve surgery relative to traditional sternotomy.

METHODS

All isolated mitral valve repairs performed in our health system from March 2012 through September 2013 were analyzed. To ensure like sets of patients, only those patients who underwent isolated mitral valve repairs with preoperative Society of Thoracic Surgeons scores of less than 4 were included in this study. A total of 159 patients were identified (sternotomy, 68; mini, 91). Total incurred direct cost was obtained from hospital financial records.

RESULTS

Analysis demonstrated no difference in total cost (operative and postoperative) of mitral valve repair between mini and sternotomy ($25,515 ± $7598 vs $26,049 ± $11,737; P = .74). Operative costs were higher for the mini cohort, whereas postoperative costs were significantly lower. Postoperative intensive care unit and total hospital stays were both significantly shorter for the mini cohort. There were no differences in postoperative complications or survival between groups.

CONCLUSIONS

Minimally invasive mitral valve surgery can be performed with overall equivalent cost and shorter hospital stay relative to traditional sternotomy. There is greater operative cost associated with minimally invasive mitral valve surgery that is offset by shorter intensive care unit and hospital stays.

Sternal talon offers a solution for secondary sternum osteosynthesis in patients with nonunion

BACKGROUND

Median sternotomy may be associated with postoperative complications such as nonunion after conventional metal wire closure. The Sternal Talon device (KLS Martin, Jacksonville, FL) has recently been introduced as an alternative for osteosynthesis after median sternotomy and may also be beneficial for patients with persistent sternal nonunion.

METHODS

A consecutive series of 24 patients underwent Sternal Talon repair for sternal nonunion or acute mediastinitis, or both, after sternal wire closure. Patient data--including demographics, surgical history, and indication for operation, as well as outcomes--were obtained and analyzed by retrospective chart review.

RESULTS

The average patient age was 61.3 years and 23 patients were men (95.8%). The most common median sternotomy procedure was coronary artery bypass grafting (CABG) in 19 patients (79.2%). Secondary closure using the Sternal Talon was indicated for sternal nonunion or infection, or both, in all patients. Eight patients underwent simultaneous muscle flap procedures during the placement of the Sternal Talon (33.3%). Sternal union was eventually achieved in 23 of 24 patients (95.8%). Subsequent reoperation was required in 4 patients (16.7%).

CONCLUSIONS

The data presented suggest that the osteosynthesis using the Sternal Talon device is a safe and effective modality for treating symptomatic sternal nonunion or acute dehiscence associated with infection (mediastinitis.).

Stroke after aortic valve surgery: results from a prospective cohort

BACKGROUND

The incidence and impact of clinical stroke and silent radiographic cerebral infarction complicating open surgical aortic valve replacement (AVR) are poorly characterized.

METHODS AND RESULTS

We performed a prospective cohort study of subjects ≥65 years of age who were undergoing AVR for calcific aortic stenosis. Subjects were evaluated by neurologists preoperatively and postoperatively and underwent postoperative magnetic resonance imaging. Over a 4-year period, 196 subjects were enrolled at 2 sites (mean age, 75.8±6.2 years; 36% women; 6% nonwhite). Clinical strokes were detected in 17%, transient ischemic attack in 2%, and in-hospital mortality was 5%. The frequency of stroke in the Society for Thoracic Surgery database in this cohort was 7%. Most strokes were mild; the median National Institutes of Health Stroke Scale was 3 (interquartile range, 1-9). Clinical stroke was associated with increased length of stay (median, 12 versus 10 days; P=0.02). Moderate or severe stroke (National Institutes of Health Stroke Scale ≥10) occurred in 8 (4%) and was strongly associated with in-hospital mortality (38% versus 4%; P=0.005). Of the 109 stroke-free subjects with postoperative magnetic resonance imaging, silent infarct was identified in 59 (54%). Silent infarct was not associated with in-hospital mortality or increased length of stay.

CONCLUSIONS

Clinical stroke after AVR was more common than reported previously, more than double for this same cohort in the Society for Thoracic Surgery database, and silent cerebral infarctions were detected in more than half of the patients undergoing AVR. Clinical stroke complicating AVR is associated with increased length of stay and mortality.

Minimally invasive mitral valve surgery utilizing heart port technology

OBJECTIVE

To determine operative outcomes of right mini-thoracotomy mitral valve surgery utilizing port access technology in first-time and reoperative cardiac surgery patients.

METHODS

From 2002 to 2011, 881 patients underwent minimally invasive mitral valve surgery. Of these, 154 patients had previous cardiac operations via sternotomy (Group 1), of which 18 (12%) had two previous operations. Seven hundred and twenty-seven patients had no previous cardiac operations (Group 2).

RESULTS

Patient demographics were similar in both groups. In Group 1, 76 (49%) patients had previous coronary artery bypass grafting, 13 (8%) had previous aortic valve surgery, and 57 (37%) had previous mitral valve surgery. Preoperative echo findings for Groups 1 and 2 included severe mitral regurgitation (MR) (88%, n = 135; 94%, n = 687), mitral stenosis (MS) (4%, n = 6; 2%, n = 12), MS + MR (8%, n = 13; 4%, n = 28), and ejection fraction (48%, 56%). Operative procedures in Groups 1 and 2 were MV repair (54%, n = 84; 89%, n = 645) and MV replacement (46%, n = 70; 11%, n = 82). Circulatory management techniques for Groups 1 and 2 included endoballoon (75%, n = 116; 79%, n = 576), Chitwood clamp (8%, n = 12; 20%, n = 147), and fibrillatory arrest (17%, n = 30; 0.5%, n = 4). Perioperative outcomes were: stroke: 2.5%, 1.6%; reoperation for bleeding: 5%, 6%; valvular reoperation rate: 0.6%, 2%; aortic dissection: 2.5%, 1%; and wound infection: 0%, 0%. Transfusion requirement was 49% (n = 76) and 31% (n = 232), respectively. Median hospital stay was seven and seven days, respectively. On postoperative echocardiography, 98% (n = 151) and 99% (n = 718) of patients had zero or trace MR (1+) with 100% freedom from MR > 2+. In-hospital mortality was 3% (n = 5) and 1% (n = 8).

CONCLUSIONS

Operative outcomes with minimally invasive mitral valve surgery utilizing port access technology can be performed safely. Stroke rate was higher in the reoperative cases (p = NS) although similar to reports evaluating redo sternotomy in mitral valve cases.

Validation study of Doppler-derived transmitral valve gradients compared to near simultaneously obtained directly measured catheter gradients immediately after mitral valve repair surgery

OBJECTIVE

To evaluate the accuracy of Doppler-derived transmitral valve gradients immediately after mitral valve repair by comparing them with near simultaneously obtained direct catheter gradients.

DESIGN

A prospective study.

SETTING

A tertiary care medical center.

PARTICIPANTS

Twenty elective adult surgical patients presenting for mitral valve repair surgery.

METHODS

Mitral valve surgery proceeded in standard fashion except for the use of a smaller than usual left ventricular vent catheter (Medtronic DLP 10 French left heart vent catheter). After completion of the mitral valve repair and subsequent cardiac de-airing, the patient was weaned from cardiopulmonary bypass. Immediately after separation, the study period began. Near simultaneous transmitral Doppler gradients were obtained with directly measured catheter gradients via the vent catheter.

RESULTS

While the mean peak gradient difference of 1.1 mmHg was small (p-value 0.18, 95% CI: -0.54 to 2.73 mmHg), the correlation between Doppler and catheter gradient measurements (Pearson correlation coefficient r = 0.54, p = 0.055) only approached statistical significance due to the large variance associated with the small sample size. In all patients with a peak gradient greater than 10 mmHg (4 of the 20 patients), overestimation of catheter gradients by Doppler occurred, with two showing a 62% to 73% discrepancy. In these two cases, there was also evidence for elevated left ventricular end-diastolic pressure (LVEDP) along with high transmitral blood flow velocities.

CONCLUSION

Doppler-derived transmitral gradients provide a simple, safe, and reliable measure of the true physiologic transmitral valve gradient. At the same time, it is important to recognize that significant Doppler over-estimation of catheter gradients may occur in patients with elevated Doppler transmitral velocities. The causes of these overestimations are unknown. They may be related to technical recording errors. They may also be related to an inherent weakness in Doppler technology--its inability to account for any distal recovery of pressure, which in a select group of patients could be significant.

Minimally invasive approach provides at least equivalent results for surgical correction of mitral regurgitation: a propensity-matched comparison

OBJECTIVE

Minimally invasive approaches to mitral valve surgery are increasingly used, but the surgical approach must not compromise the clinical outcome for improved cosmesis. We examined the outcomes of mitral repair performed through right minithoracotomy or median sternotomy.

METHODS

Between January 2002 and October 2011, 1011 isolated mitral valve repairs were performed in the University of Pennsylvania health system (455 sternotomies, 556 right minithoracotomies). To account for key differences in preoperative risk profiles, propensity scores identified 201 well-matched patient pairs with mitral regurgitation of any cause and 153 pairs with myxomatous disease.

RESULTS

In-hospital mortality was similar between propensity-matched groups (0% vs 0% for the degenerative cohort; 0% vs 0.5%, P = .5 for the overall cohort; in minimally invasive and sternotomy groups, respectively). Incidence of stroke, infection, myocardial infarction, exploration for postoperative hemorrhage, renal failure, and atrial fibrillation also were comparable. Transfusion was less frequent in the minimally invasive groups (11.8% vs 20.3%, P = .04 for the degenerative cohort; 14.0% vs 22.9%, P = .03 for the overall cohort), but time to extubation and discharge was similar. A 99% repair rate was achieved in patients with myxomatous disease, and a minimally invasive approach did not significantly increase the likelihood of a failed repair resulting in mitral valve replacement. Patients undergoing minimally invasive mitral repair were more likely to have no residual post-repair mitral regurgitation (97.4% vs 92.1%, P = .04 for the degenerative cohort; 95.5% vs 89.6%, P = .02 for the overall cohort). In the overall matched cohort, early readmission rates were higher in patients undergoing sternotomies (12.6% vs 4.4%, P = .01). Over 9 years of follow-up, there was no significant difference in long-term survival between groups (P = .8).

CONCLUSIONS

In appropriate patients with isolated mitral valve disease of any cause, a right minithoracotomy approach may be used without compromising clinical outcome.

Mitral valve repair is superior to valve replacement for the early preservation of cardiac function: relation of ventricular geometry to function

The immediate effect or mitral valve repair (MVP) or replacement (MVR) on cardiac function was compared in patients with mitral regurgitation in relation to the changes in left ventricular (LV) function and geometry by using intraoperative transesophageal echocardiography in 29 patients with MVP and 21 patients with MVR, before and immediately after cardiopulmonary bypass. The LV volumes, ejection fraction, and long-axis and short-axis lengths and eccentricity index (ratio of long axis to short axis) at end-systole and end-diastole were measured. After both MVP and MVR, there were significant decreases in LV end-diastolic volume (p < 0.0001). However, the ejection fraction did not change after MVP, whereas it decreased after MVR (p < 0.0001). After MVP, there was an increase in eccentricity index at end-systole (p < 0.0001). After MVR, there was no decrease in end-systolic volume, and the eccentricity index was lower than that after MVP (p < 0.0001). The change in LV ejection fraction correlated with the changes in eccentricity index at end-systole (r = 0.55; p < 0.0001) and end-diastole (r = 0.42; p < 0.0003). Immediate intraoperative LV function is preserved after MVP but is depressed after MVR for mitral regurgitation. The changes in ejection fraction correlate with changes in ventricular geometry.

Effect of subendocardial resection on sinus rhythm endocardial electrogram abnormalities

BACKGROUND

Patients with sustained ventricular tachycardia after acute myocardial infarction frequently have characteristic abnormalities of left ventricular endocardial electrical activity, including fractionated (prolonged, multicomponent, low-amplitude), split (having discrete widely separated deflections), and late (extending after the end of the QRS complex) electrograms. The exact cause and source of these electrograms are not clear.

METHODS AND RESULTS

In this study, endocardial electrograms from 18 patients were recorded with a 20-electrode array from the same area immediately before and immediately after resection of subendocardial tissue at the time of surgery for ventricular tachycardia. Electrograms could be compared before and after resection from 298 of 360 (83%) of the electrodes. Before resection, split electrograms were present in 130 (44%) and late components in 81 (27%) of the recordings. Recordings made after resection showed fewer abnormalities, including complete absence of split electrograms as well as all previously recorded late components (P < .02). Mean electrogram amplitude increased from 0.5 +/- 0.8 to 1.0 +/- 1.6 mV (P < .0001) because of removal of the attenuating effect of endocardial scar; mean duration decreased from 112 +/- 38 to 65 +/- 27 ms (P < .0001) mainly because of loss of late and split components. Overall electrogram contour was very similar aside from these changes.

CONCLUSIONS

These data show that (1) some of the signal recorded on the endocardial surface is derived from deeper tissue layers and (2) split and late electrogram components appear to be generated by cells in the superficial endocardial layers, since they are eradicated by removal of this tissue. These findings correspond well with previous histological studies of resection specimens that show bundles of surviving muscle cells separated by layers of dense scar that act as an insulator.

Endocardial resection in the treatment of ventricular tachycardia secondary to cardiac trauma

Sustained ventricular tachycardia with left ventricular aneurysm formation is a rare complication following penetrating cardiac trauma. We present an unusual case of serious ventricular tachycardia which developed 35 years after a World War II injury and was successfully treated with aneurysmectomy, map-guided subendocardial resection, and cryoablation.

Large animal model of left ventricular aneurysm

In 28 Dorsett sheep, ligation of the distal homonymous (equivalent to human left anterior descending) and second diagonal coronary arteries produced a constant transmural infarct of 22.9% +/- 2.5% (mean +/- standard deviation) of the left ventricular mass. Serial left ventriculograms showed that within four hours the infarct segment expands, wall thickness decreases, and aneurysmal dilatation occurs and progresses over the next 60 days in all sheep. Epicardial ventricular point references indicated that adjacent noninfarcted myocardium participates in the formation of the aneurysm. Anatomy of the coronary vasculature was studied in 22 excised sheep hearts. In sheep, coronary arterial anatomy is remarkably constant. The left coronary artery provides all of the blood supply to the left ventricle and septum and only a small rim of both the anterior and posterior right ventricles. Cardiac veins from the left ventricle drain into the coronary sinus, which also receives the left azygos vein. Right ventricular veins drain separately. The essentially separate coronary circulations to the two ventricles, the paucity of coronary collateral circulation, and the consistent evolution of left ventricular infarcts into aneurysms are important advantages of the ovine model for both metabolic and ventricular mechanical studies of acute myocardial infarction and left ventricular aneurysm.

Risk stratification and management of patients with recurrent ventricular tachycardia and other malignant ventricular arrhythmias

Clinical results are reviewed in 269 patients who underwent subendocardial resection for recurrent sustained ventricular tachycardia secondary to ischemic heart disease. Operative mortality is 15%. Factors increasing operative mortality rates are ejection fraction less than 20%, emergency operation, and history of previous heart operation. Use of amiodarone preoperatively does not alter operative risk. Clinical control of ventricular tachycardia is achieved in 93% of operative survivors. Two thirds of these patients do not need antiarrhythmic agents. Five-year actuarial survival is approximately 60%. Patient results with the automatic internal cardioverter defibrillator at the Hospital of the University of Pennsylvania and nationwide are also reviewed. As of June 1987, almost 1,500 patients had one or more devices implanted. Most patients had a prior documented cardiac arrest. Coronary artery disease is the cause of heart disease in over 70% of patients. Operative mortality is low (0.8-3.9%). Approximately 50% of patients have had therapeutic discharge of the device; however, asymptomatic discharge occurs in up to 45% of patients. Incidence of sudden death is 1.5% at 1 year and 5% at 5 years. Five-year actuarial survival is approximately 60%. Long-term mortality is primarily from heart failure.

Surgery for left ventricular aneurysm. Early survival with and without endocardial resection

In the past 3 years, 86 patients had left ventricular aneurysms resected or plicated. Sixty-eight had recurrent sustained ventricular tachycardia as the indication for surgery and had preoperative and intraoperative electrophysiologic mapping. There were 14 hospital deaths (16%). Eight preoperative potential risk factors for early hospital mortality were analyzed by multivariate analysis. Only acute myocardial infarction within 30 days before surgery correlated with hospital death at the p less than 0.05 level. History of previous heart surgery and advanced New York Heart Association functional class were important risk factors at the p less than 0.1 level. Hospital mortality was 17.6% for patients who had intraoperative mapping and endocardial resection and 11.1% for the others. Patients who had aneurysm repair for ventricular tachycardia had a significantly higher incidence of low cardiac output early after surgery (p less than 0.025).

Surgical decisions in the management of sudden cardiac death and malignant ventricular arrhythmias. Subendocardial resection, the automatic internal defibrillator, or both

Subendocardial resection and implantation of an automatic implantable cardioverter/defibrillator are the current preferred treatments for the management of drug-resistant malignant ventricular arrhythmias and sudden cardiac death. We reviewed retrospectively the case histories of 269 patients who had subendocardial resection and 77 patients who had defibrillator implantation to define clinical characteristics of each group and compare operative and long-term results. All patients treated by subendocardial resection had recurrent sustained ventricular tachycardia as a result of a myocardial infarction. From the standpoint of arrhythmia substrate and cardiac disease, patients receiving the defibrillator were a more heterogeneous group. Forty-eight (62%) had coronary artery disease, 28 (36%) cardiomyopathy, and one patient had a primary electrical abnormality. Among patients receiving the defibrillator, 55% had sustained ventricular tachycardia and 45% polymorphic ventricular tachycardia or ventricular fibrillation. Overall ventricular function was similar in the two groups. Operative mortality rate was better in the group having defibrillator implantation (3% versus 15%). Complications related to the defibrillator device or implantation occurred in 46 (60%) patients, with asymptomatic shocks occurring in 35 patients (45%). Since the defibrillator was not designed to prevent arrhythmias, the arrhythmia-free survival rate was much better in the group having subendocardial resection (95% versus 44% at 3 years). Fewer patients treated by subendocardial resection required antiarrhythmic medications (33% versus 66%). The actuarial survival rate was similar in the two groups (approximately 60% at 4 years), with heart failure the most common cause of death. Thus both subendocardial resection and defibrillator implantation are highly effective in preventing sudden cardiac death. The choice of procedure depends on (1) arrhythmia diagnosis, (2) cardiac disease, and (3) intangible factors.

Coronary artery bypass surgery prior to resection of abdominal aortic aneurysm in patients with unstable coronary artery disease

Coronary artery disease (CAD) is associated with abdominal aortic aneurysm in greater than 60% of cases. CAD continues to affect postoperative complication rates. Half of the deaths that follow resection of abdominal aortic aneurysms are due to perioperative myocardial infarctions. On evaluation for surgical resection of an abdominal aortic aneurysm, six patients were found to have significant CAD. Each underwent coronary artery bypass surgery prior to elective resection of the aneurysm. No deaths or myocardial infarctions occurred following any of the procedures. We restrict our indications for coronary angiography to the evaluation of patients with unstable angina (pain at rest or after minimal exertion) in whom noninvasive studies reveal evidence of CAD, and for patients who are unresponsive to medical management.

Cardiac cryolesions: factors affecting their size and a means of monitoring their formation

Twenty-seven endocardial cryolesions were created in mongrel dogs and analyzed to determine the effects on cryolesion size of both the initial myocardial temperature (37 degrees C versus 12 degrees C) and the pressure within the nitrous oxide delivery line (tank pressure of more than 700 pounds per square inch [psi] versus tank pressure of less than 700 psi). In addition, local myocardial temperatures were monitored to determine their utility in the intraoperative determination of the extent of cryothermic cell death. Cryolesion volume was significantly affected by both the initial myocardial temperature (p less than 0.001) and the line pressure (p = 0.014). In a 37 degrees C myocardium, the mean lesion volume ranged from 0.501 +/- 0.183 cc at line pressures lower than 700 psi to 0.839 +/- 0.258 cc at line pressures greater than 700 psi. In a 12 degrees C myocardium, the mean volume was 1.151 +/- 0.436 cc at line pressures lower than 700 psi and 1.361 +/- 0.288 cc at line pressures higher than 700 psi. A myocardial temperature of 0 degrees C occurs at the edge of the area of cell death. When analyzing the range from -5 degrees to +5 degrees C, the probability of a point at or lower than 0 degrees C falling inside the cryolesion is 84.2%. Monitoring intramyocardial temperature will predict the border of a cryolesion.

Relation of the intraoperative defibrillation threshold to successful postoperative defibrillation with an automatic implantable cardioverter defibrillator

To determine the relation between the intraoperative defibrillation threshold and successful postoperative termination of induced ventricular fibrillation (VF) with the automatic implantable cardioverter defibrillator (AICD), 33 patients who underwent AICD implantation were studied. The defibrillation threshold, determined after at least 10 seconds of VF, was 5 J in 2, 10 J in 6, 15 J in 10, 20 J in 10 and 25 J in 5 patients. The AICD energy rating on the first discharge was 28 +/- 1.8 J. Defibrillation of induced VF was demonstrated postoperatively in 29 of 33 (88%) patients. The AICD terminated VF postoperatively in all 18 patients with a defibrillation threshold less than or equal to 15 J. Only 11 of the 15 (73%) patients with a defibrillation threshold greater than or equal to 20 J (p less than 0.04) had VF terminated postoperatively. In all 4 patients in whom the AICD failed to terminate induced VF, the energy difference between the AICD rating and the defibrillation threshold was less than or equal to 10 J. Among the 14 patients with a difference of less than or equal to 10 J between the AICD energy rating and the defibrillation threshold, there were no significant differences between the 4 patients with and the 10 without successful VF termination with respect to the duration of VF induced postoperatively or the AICD lead system. In summary, failure to terminate VF with the AICD is not uncommon (27%) when the defibrillation threshold approaches the energy delivering capacity of the AICD.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior left ventricular aneurysm: factors associated with the development of sustained ventricular tachycardia

Fifty patients with anteroapical left ventricular aneurysm secondary to prior myocardial infarction underwent aneurysmectomy, at which time endocardial sinus rhythm mapping was performed. Forty patients had a history of recurrent sustained monomorphic ventricular tachycardia, and 10 had an aneurysm but no history of spontaneous sustained tachycardia. A comparison of the clinical, angiographic and sinus rhythm endocardial electrographic characteristics of these two groups revealed that the patients without spontaneous ventricular tachycardia had more severe coronary artery disease (2.6 +/- 0.5 versus 1.9 +/- 0.8 coronary arteries having greater than 70% stenosis; p less than 0.03), underwent surgery earlier after infarction (3 +/- 2 versus 46 +/- 53 months; p less than 0.03) and had less extensive wall motion abnormalities on contrast ventriculography (0 of 8 versus 13 of 35 patients assessed had an abnormally contracting ventriculographic segment length greater than 60%; p less than 0.04). During intraoperative programmed electrical stimulation, all 40 patients with and 4 of 10 without a history of spontaneous ventricular tachycardia had inducible tachycardia. The patients with inducible tachycardia had a larger area of endocardium from which abnormal electrograms (duration greater than 70 ms or amplitude less than 0.7 mV) were recorded (62 +/- 17 versus 45 +/- 20% of electrograms; p less than 0.03) as well as fractionated (duration greater than 90 ms, amplitude less than 0.3 mV) electrograms (20 +/- 14 versus 9 +/- 7% of electrograms; p less than 0.04) than did patients without inducible tachycardia, but there were no angiographic differences between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved results in the operative management of ventricular tachycardia related to inferior wall infarction. Importance of the annular isthmus

Ventricular tachycardia associated with inferior wall myocardial infarction has had a lower surgical cure rate with localized subendocardial resection than ventricular tachycardia related to anterior infarction. Some investigators have advocated visually directed extensive subendocardial resection, including resection of the papillary muscles and mitral valve replacement, even without documenting the origin of ventricular tachycardia at these sites. We have operated on 46 patients (43 men and three women) for ventricular tachycardia associated with inferior wall myocardial infarction. Thirty-one consecutive patients (Group I) had standard localized subendocardial resection. Two patients in this group had mitral valve replacement for mitral insufficiency. Fifteen consecutive recent patients (Group II) underwent subendocardial resection plus focal endocardial cryoablation (3 minutes at -70 degrees C) of the annular isthmus. The annular isthmus is defined as the ventricular muscle between the basal end of the ventriculotomy and the mitral valve anulus. In Group I there were four operative deaths (13%). Ventricular tachycardia was noninducible in 15 of 27 operative survivors (56%) at postoperative electrophysiologic studies. In Group II there was one operative death (7%) and 13 of 14 survivors (93%) had no inducible ventricular tachycardia at postoperative electrophysiologic studies (p less than 0.01 versus Group I). No Group II patient required mitral valve replacement. Six operative survivors in Group II had intraoperative activation maps consistent with macroreentry incorporating the annular isthmus. Group I and Group II were indistinguishable in terms of preoperative hemodynamics, number of coronary arteries diseased, or the presence of left ventricular aneurysm. These results suggest that subendocardial resection with additional cryoablation of the annular isthmus results in improved control of ventricular tachycardia in patients with ventricular tachycardia associated with inferior wall myocardial infarction. Mitral valve replacement is not required unless intrinsic mitral valve disease is present. These data also suggest that the annular isthmus is a critical component of the reentrant circuit in these tachycardias.

Traumatic coronary artery fistula

Coronary artery fistulas can occur in patients who survive cardiac trauma. We report one such case with development of a right coronary artery-right atrial fistula 2 years after injury. The literature shows that surgical correction should be performed before the development of incapacitating symptoms (angina, pulmonary hypertension, congestive heart failure). Proximal and distal ligation of the affected coronary artery with distal bypass grafting is the recommended surgical procedure. Other procedures have led to recurrence of the fistula.

The automatic implantable cardioverter-defibrillator: efficacy, complications, and device failures

Twenty-six patients with refractory ventricular arrhythmias received the automatic implantable cardioverter-defibrillator. A patch lead only was placed during arrhythmia surgery in 7 other patients. During 13 +/- 6 (SD) months, the device discharged in 10 patients because of a sustained ventricular arrhythmia. No sudden deaths occurred. There were 31 complications in 17 patients, including postoperative refractory heart failure, coronary artery erosion, subclavian vein thrombosis, postoperative stroke after conversion of atrial fibrillation, atelectasis with pneumonia, symptomatic pleural effusions, and infection at the generator site. The cardioverter-defibrillator discharged in 9 asymptomatic patients, failed to terminate ventricular fibrillation during postoperative testing in 3 patients, and had premature battery failure in 4 patients. Tachycardia slowing during chronic amiodarone therapy and unipolar ventricular pacing during ventricular fibrillation precluded or delayed arrhythmia sensing. Thus, the cardioverter-defibrillator can be life saving, but its potential complications and interactions with antiarrhythmic drugs and pacemakers must be considered at patient selection.

Pattern of endocardial activation during sustained ventricular tachycardia

Fifty-five patients with sustained ventricular tachycardia due to prior myocardial infarction underwent intraoperative endocardial activation mapping during ventricular tachycardia to guide subendocardial resection. The mapping data were analyzed to determine the pattern of endocardial activation during tachycardia. Of a total of 122 tachycardias, 101 had a pattern of activation assigned: in 90 (90%), endocardial activation spread centrifugally from a tachycardia site of origin, and 11 (10%) had a continuous loop of electrical activity around an aneurysm. All patients had at least one tachycardia having the centrifugal spread pattern. Tachycardias with a continuous loop pattern had a shorter mean cycle length than those with a centrifugal spread pattern (260 +/- 33 versus 338 +/- 81 ms, p less than 0.002) and a longer duration of endocardial activation relative to the tachycardia cycle length (100 +/- 0 versus 58 +/- 19%, p less than 0.001). There was no difference in preoperative patient characteristics, operative survival or cure of tachycardia between patients having any tachycardias of the continuous loop pattern and those having only centrifugal spread tachycardias. Thus, the vast majority of ventricular tachycardias in this group of patients are characterized by a centrifugal spread of endocardial activation from a site of origin less than 6 cm2 in size. Mapping-guided ablative surgery may remove the entire tachycardia circuit in these patients and a critical portion of the circuit in the minority of patients with continuous loop tachycardias.