Surgical options for aortic root aneurysm disease: which procedure, which patient.

PURPOSE OF REVIEW: Several surgical repair strategies are available for patients with aortic root aneurysms. This review summarizes the indications for surgery, surgical treatment options, as well their associated outcomes. RECENT FINDINGS: Despite the development and increasing adoption of valve sparing aortic root replacement, most patients with aortic root aneurysms still undergo placement of a composite valved graft. Valve sparing aortic root replacement may have a lower rate of bleeding and thrombotic complications during long-term follow-up with excellent long-term survival and low rates of aortic valve reintervention. SUMMARY: Patients with aortic root aneurysms who are symptomatic or reach the recommended size criteria should undergo surgical repair. Most patients receive composite valve graft conduits with good outcomes. The presence of normal aortic leaflet tissue and minimal regurgitation, including those with connective tissue disorders, should be evaluated for valve sparing aortic root replacement. Valve sparing procedures are durable and obviate the need for lifelong anticoagulation and avoid the risk of structural degeneration of bioprosthetic valves.

Is anticoagulation with bivalirudin comparable to heparin for pediatric extracorporeal life support? Results from a high-volume center.

There is a paucity of data regarding the use of direct thrombin inhibitors such as bivalirudin for children on extracorporeal life support (ECLS). We sought to compare the outcomes of children on ECLS anticoagulated with bivalirudin versus heparin. Patients transitioned from heparin to bivalirudin were treated as a separate group. A single-institution, retrospective review of all consecutive children (neonate to 18 years) placed on ECLS in the cardiac or pediatric intensive care units was performed (June 2018-December 2019). Data collected included demographics, anticoagulation strategy, number of circuit interventions, blood product use on ECLS, survival to decannulation, and survival to discharge. Fifty-four children were placed on ECLS for a total of 56 runs. Demographics and venovenous versus venoarterial ECLS were similar. The bivalirudin group had longer median duration of support compared to the heparin group--11.0 days [IQR 6.2, 23.1] versus 3.3 days [2.1, 6.2], P < .001. Patients switched from heparin to bivalirudin had a similar duration of support (10.3 days [8.3, 18.3]) as those on bilvalirudin alone. However, there was no difference in red blood cell, fresh frozen plasma, or platelet transfusions. There was no difference in the number of circuit interventions, survival to decannulation or discharge. The freedom to first circuit intervention was longer with bivalirudin compared to heparin. Our data suggest that even with longer pediatric ECLS runs on bivalirudin, there were no differences in the outcomes between the heparin and bivalirudin groups, with longer freedom from first circuit intervention with bivalirudin. While this is the largest reported series comparing children on ECLS anticoagulated with heparin versus bivalirudin, larger studies are needed to determine the optimal anticoagulation strategy for this diverse and complicated group of children.

Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia.

BACKGROUND: Recent advances have enabled noninvasive mapping of cardiac arrhythmias with electrocardiographic imaging and noninvasive delivery of precise ablative radiation with stereotactic body radiation therapy (SBRT). We combined these techniques to perform catheter-free, electrophysiology-guided, noninvasive cardiac radioablation for ventricular tachycardia. METHODS: We targeted arrhythmogenic scar regions by combining anatomical imaging with noninvasive electrocardiographic imaging during ventricular tachycardia that was induced by means of an implantable cardioverter-defibrillator (ICD). SBRT simulation, planning, and treatments were performed with the use of standard techniques. Patients were treated with a single fraction of 25 Gy while awake. Efficacy was assessed by counting episodes of ventricular tachycardia, as recorded by ICDs. Safety was assessed by means of serial cardiac and thoracic imaging. RESULTS: From April through November 2015, five patients with high-risk, refractory ventricular tachycardia underwent treatment. The mean noninvasive ablation time was 14 minutes (range, 11 to 18). During the 3 months before treatment, the patients had a combined history of 6577 episodes of ventricular tachycardia. During a 6-week postablation "blanking period" (when arrhythmias may occur owing to postablation inflammation), there were 680 episodes of ventricular tachycardia. After the 6-week blanking period, there were 4 episodes of ventricular tachycardia over the next 46 patient-months, for a reduction from baseline of 99.9%. A reduction in episodes of ventricular tachycardia occurred in all five patients. The mean left ventricular ejection fraction did not decrease with treatment. At 3 months, adjacent lung showed opacities consistent with mild inflammatory changes, which had resolved by 1 year. CONCLUSIONS: In five patients with refractory ventricular tachycardia, noninvasive treatment with electrophysiology-guided cardiac radioablation markedly reduced the burden of ventricular tachycardia. (Funded by Barnes-Jewish Hospital Foundation and others.).

Efficacy of a surgical cardiac ablation clamp using nanosecond pulsed electric fields: An acute porcine model.

OBJECTIVE: To examine the effectiveness of a recently developed nonthermal technology, nanosecond pulse-field ablation (nsPFA), for surgical ablation of the atria in a beating heart porcine model. METHODS: Six pigs underwent sternotomy and ablation using an nsPFA parallel clamp. The ablation electrodes (53 mm long) were embedded in the jaws of the clamp. Nine lesions per pig were created in locations chosen to be representative of the Cox-maze procedure. Four lesions were intended to electrically isolate parts of the atrium: the right atrial appendage, left atrial appendage, right pulmonary veins, and left pulmonary veins. For these lesions, exit block testing was performed both after ablation and before euthanasia; the time between the 2 tests was 3.3 ± 0.5 hours (range, 2-4 hours). Using purse string sutures, 5 more lesions were created up to the superior vena cava, down to the inferior vena cava, across the right atrial free wall, and at 2 distinct locations on the left atrial free wall. The clamp delivered a train of nanosecond duration pulses, with a total duration of 2.5 seconds, independent of tissue thickness. The heart tissue was stained with 1% triphenyltetrazolium chloride after a dwelling period of 2 hours. Subsequently, each lesion was cross sectioned at 5-mm intervals to assess the ablation depth and transmurality. In some sections, transmurality could not be established on the basis of triphenyltetrazolium chloride staining alone; for these lesions, Gomori-trichrome stains were used, and the histologic sections were evaluated for transmurality. RESULTS: The ablation time was 2.5 seconds per lesion, for a total of only 22.5 seconds ablation time to create 9 lesions. A total of 53 lesions were created, resulting in 388 separate histologic sections. Transmurality was established in 386 sections (99.5%). Mean tissue thickness was 3.1 ± 1.5 mm (range, 0.2-8.6 mm). Exit block was confirmed in 23 of the 24 lesions (96%) postablation and 23 of 24 (96%) before the animals were humanely killed. Over the course of the procedure, neither pulse-induced arrhythmias nor any other complications were noted. CONCLUSIONS: The novel nsPFA clamp device was effective in creating acute conduction block and transmural lesions in both the right and left atria in an acute porcine model. This nonthermal energy source has great potential to both shorten procedural time and enable effective ablation in the beating heart.

Percutaneous decannulation reduces procedure length and rates of groin wound infection in patients on venoarterial extracorporeal membrane oxygenation.

Objective: Open decannulation from femoral venoarterial extracorporeal membrane oxygenation (VA-ECMO) carries high risk of morbidity, including groin wound infection. This study evaluated the impact of percutaneous decannulation on rates of groin wound infection in patients decannulated from femoral VA-ECMO. Methods: Between January 1, 2022, and April 30, 2023, 47 consecutive patients received percutaneous femoral VA-ECMO and survived to decannulation. A percutaneous suture-mediated closure device was used for decannulation in patients with relatively smaller arterial cannulas. Patients with larger arterial cannulas or unsuccessful percutaneous closures underwent surgical cutdown and repair of the femoral artery. The primary outcome was arterial site wound infection following decannulation. Results: Among the 47 patients who survived to decannulation from VA-ECMO, 21 underwent percutaneous decannulation and 27 underwent surgical cutdown. One patient underwent 2 VA-ECMO runs, one with percutaneous decannulation and one with surgical cutdown. Percutaneous decannulation was attempted in 22 patients, with 21 of 22 (95.5%) success rate. Decannulation procedure length was significantly shorter in the percutaneous group (79 minutes vs 148 minutes, P = .0001). The percutaneous group had significantly reduced rates of groin wound complications (0% vs 40.7%, P = .001) and groin wound infections (0% vs 22.2%, P = .03) when compared with the surgical cutdown group. Three patients (14.3%) in the percutaneous group experienced vascular complications, including pseudoaneurysm at the distal perfusion catheter site and nonocclusive thrombus of the common femoral artery. Conclusions: Percutaneous decannulation may reduce decannulation procedure length and rate of groin wound infection in patients who survive to decannulation from VA-ECMO.

Performance of an Irrigated Bipolar Radiofrequency Ablation Clamp on Explanted Human Hearts.

BACKGROUND: Bipolar radiofrequency (RF) clamps are commonly used during surgical ablation for atrial fibrillation (AF). This study examined the efficacy of an irrigated bipolar RF clamp to create transmural lesions in an ex vivo human heart model. METHODS: Ten donor hearts, turned down for transplantation, were explanted and arrested with cold cardioplegia. The ablations of the Cox Maze IV procedure were performed using the Cardioblate LP (Medtronic, Inc) irrigated bipolar RF clamp. In the first 5 hearts, each lesion was created with a single application of RF, whereas in the remaining 5 hearts, each lesion was created with a double application of RF without unclamping. Each lesion was cross-sectioned and stained with 2,3,5-triphenyl-tetrazolium chloride to assess ablation depth and transmurality. RESULTS: A total of 100 lesions were analyzed. In the single-ablation group, 222 of 260 sections (85%) and 37 of 50 lesions (74%) were transmural. The efficacy improved significantly in the double-ablation group, in which 348 of 359 sections (97%, P < .001) and 46 of 50 lesions (92%, P = .017) were transmural. Overall, in nontransmural lesions, the epicardial fat thickness was significantly greater (1.69 ± 0.70 mm vs 0.45 ±0.10 mm, P < .001) than the transmural lesions. CONCLUSIONS: A single ablation on human atrial tissue with an irrigated bipolar RF clamp was insufficient to reliably create transmural lesions, but a double ablation significantly increased the lesion and section transmurality. Nontransmural lesions were associated with significantly thicker layers of epicardial fat, which likely decreased tissue energy delivery due to the higher resistance of fat to current flow.

Minimally Invasive Mitral Valve Surgery With Concomitant Cox Maze Procedure Is as Effective as a Median Sternotomy With Decreased Morbidity.

OBJECTIVE: A right minithoracotomy (RMT) is a minimally invasive surgical approach that has been increasingly performed for the concomitant Cox maze IV procedure (CMP) and mitral valve surgery (MVS). Little is known regarding whether long-term rhythm and survival outcomes are affected by the RMT as compared with the traditional median sternotomy (MS) approach. METHODS: Between April 2004 and April 2021, 377 patients underwent the concomitant CMP and MVS, of whom 38% had RMT. Propensity score matching yielded 116 pairs. Freedom from atrial tachyarrhythmias (ATA) was assessed with prolonged monitoring annually for 8 years. Survival, rhythm, and perioperative outcomes were compared. RESULTS: The unmatched RMT cohort had a greater freedom from ATA recurrence at 1 year (99% vs 90%, P = 0.001) and 3 years (94% vs 86%, P = 0.045). The matched RMT cohort had longer cardiopulmonary bypass (median: 215 [199 to 253] vs 170 [136 to 198] min, P < 0.001) and aortic cross-clamp (110 [98 to 124] vs 86 [71 to 102] min, P < 0.001) times but shorter intensive care time (48 [24 to 95] vs 71 [26 to 144] h, P = 0.001) and length of stay (8 [6 to 11] vs 10 [7 to 14] h, P < 0.001). More pacemakers (18% vs 4%, P < 0.001) and postoperative transfusions (57% vs 41%, P = 0.014) occurred in the MS cohort. The 30-day mortality (P = 0.651) and 8-year survival (P = 0.072) was not significantly different between the cohorts. CONCLUSIONS: Early 1-year and 3-year freedom from ATA recurrence was better in the RMT cohort compared with the MS cohort. Despite longer operative times, the RMT cohort had shorter lengths of stay, fewer postoperative transfusions, and fewer pacemakers placed.

Delayed-enhancement cardiac magnetic resonance imaging detects disease progression in patients with mitral valve disease and atrial fibrillation.

Objectives: The mechanism by which mitral valve (MV) disease leads to atrial fibrillation (AF) remains poorly understood. Delayed-enhancement cardiac magnetic resonance imaging (DE-MRI) has been used to assess left atrial (LA) fibrosis in patients with lone AF before catheter ablation; however, few studies have used DE-MRI to assess MV-induced LA fibrosis in patients with or without AF undergoing MV surgery. Methods: Between March 2018 and September 2022, 38 subjects were enrolled; 15 age-matched controls, 14 patients with lone mitral regurgitation (MR), and 9 patients with MR and AF (MR + AF). Indexed LA volume, total LA wall, and regional LA posterior wall (LAPW) enhancement were defined by the DE-MRI. One-way analysis of variance was performed. Results: LA volume and LA enhancement were associated (r = 0.451, P = .004). LA volume differed significantly between controls (37.1 ± 10.6 mL) and patients with lone MR (71.0 ± 35.9, P = .020 and controls and patients with MR + AF (99.3 ± 47.4, P < .001). The difference in LA enhancement was significant between MR + AF (16.7 ± 9.6%) versus controls (8.3 ± 3.9%, P = .006) and MR + AF versus lone MR (8.0 ± 4.8%, P = .004). Similarly, the was significantly more LAPW enhancement in the MR + AF (17.5 ± 8.7%) versus control (9.2 ± 5.1%, P = .011) and MR + AF versus lone MR (9.8 ± 6.0%, P = .020). Conclusions: Patients with MR + AF had significantly more total and LAPW fibrosis compared with both controls and lone MR. Volume and delayed enhancement were associated, but there was no difference between MR and MR + AF.

Comparison of laparoscopic skills performance between single-site access (SSA) devices and an independent-port SSA approach.

BACKGROUND: This study compared the performance of validated laparoscopic tasks on four commercially available single-site-access (SSA) devices with the performance of those tasks on an independent-port (IP) SSA setup. METHODS: A prospective, randomized comparison of laparoscopic skills performance on four access devices (ADs) (GelPOINT, SILS Port, SSL Access System, TriPort) and one IP-SSA setup was conducted. A laparoscopic trainer box was used to train 18 (2nd- to 4th-year) medical students, four surgical residents, and five attending surgeons to proficiency in multiport laparoscopy using four laparoscopic drills (i.e., peg transfer, bean drop, pattern cutting, extracorporeal suturing). Drills then were performed in random order on each IP-SSA and AD-SSA setup using straight laparoscopic instruments. Repetitions were timed and errors recorded. Data are presented as mean ± standard deviation. Statistical analysis was performed by two-way analysis of variance (ANOVA) with Tukey HSD post hoc tests. RESULTS: The attending surgeons had significantly faster total task times than the residents or students (P < 0.001), but the difference between the residents and students was not significant. Pair-wise comparisons showed significantly faster total task times for the IP-SSA setup than for all four AD-SSAs within the student group only (P < 0.05). The total task times for the residents and attending surgeons showed a similar profile, but the differences were not significant. When the data for the three groups were combined, the total task time was less for the IP-SSA setup than for each of the four AD-SSA setups (P < 0.001). Similarly, the IP-SSA setup was significantly faster than three of the four AD-SSA setups for peg transfer, three of the four setups for pattern cutting, and two of the four setups for suturing. No significant differences in error rates between the IP-SSA and AD-SSA setups were detected. CONCLUSIONS: Compared with an IP-SSA laparoscopic setup, AD-SSAs are associated with longer task performance times in a trainer box model, independently of the level of training. Task performance was similar across the different SSA devices.

Concomitant Cox-Maze IV and Septal Myectomy in Patients With Hypertrophic Obstructive Cardiomyopathy.

BACKGROUND: In patients with hypertrophic obstructive cardiomyopathy, atrial fibrillation is associated with heart failure and increased late mortality. However, the role of surgical ablation in these patients is not well defined. The aim of this study was to evaluate the efficacy of the concomitant Cox-Maze IV procedure in patients undergoing septal myectomy for hypertrophic obstructive cardiomyopathy. METHODS: Between 2005 and 2019, 347 patients who underwent septal myectomy at a single institution (Washington University School of Medicine, Barnes-Jewish Hospital, St Louis, MO) were retrospectively reviewed. For patients with hypertrophic obstructive cardiomyopathy and atrial fibrillation who underwent a concomitant Cox-Maze IV procedure, freedom from atrial tachyarrhythmias (ATAs) on or off antiarrhythmic drugs (AADs) was evaluated annually. Predictors of ATA recurrence were identified using Fine-Gray regression, with death as a competing risk. RESULTS: A total of 42 patients underwent concomitant septal myectomy and Cox-Maze IV procedures. The majority of patients, 69% (29 of 42), had paroxysmal atrial fibrillation with a 2.5-year median duration. Operative mortality was 7% (3 of 42). New York Heart Association functional class was reduced after surgery (P < .01). Rates of freedom from recurrent ATAs at 1- and 5-year intervals were 93% (27 of 29) and 100% (14 of 14), respectively. Rates of freedom from ATAs and AADs were 83% (24 of 29) and 100% (14 of 14) at the same time points, respectively. Increased left atrial diameter predicted first ATA recurrence (P < .01). Cerebrovascular accident risk was lower in patients with atrial fibrillation who underwent concomitant Cox-Maze IV and septal myectomy relative to myectomy only (P = .02). CONCLUSIONS: Late freedom from ATAs on or off AADs was excellent after Cox-Maze IV and septal myectomy. Although there was a higher than expected rate of perioperative complications, the study results suggest that concomitant surgical ablation should be considered in selected patients with hypertrophic obstructive cardiomyopathy and atrial fibrillation.

Surgical Ablation of Atrial Fibrillation in Patients With Tachycardia-Induced Cardiomyopathy.

BACKGROUND: Atrial fibrillation (AF) is a common cause of tachycardia-induced cardiomyopathy (TIC). This study evaluated the outcomes of the Cox-Maze IV procedure in patients with TIC and significant left ventricular dysfunction. METHODS: Between January 2002 and January 2017, 37 consecutive patients with a left ventricular ejection fraction (LVEF) of 0.40 or less underwent stand-alone surgical ablation of AF. After dilated and ischemic cardiomyopathies were excluded, 34 of 37 patients met the criteria for the diagnosis of TIC. RESULTS: Patients were a mean age of 56 ± 11 years, and 24 (70%) had long-standing persistent AF. The median AF duration was 72 months (interquartile range, 9 to 276 months). Seventeen patients (50%) had at least one catheter-based ablation that failed. Mean LVEF was 0.32 ± 0.08. There were 11 patients (32%) with New York Heart Association Functional Classification III/IV symptoms. There was one (3%) 30-day mortality caused by a pulmonary embolus, despite full anticoagulation. At 12 months, freedom from atrial tachyarrhythmias on or off antiarrhythmic drugs was 94% and 89%, respectively. Postoperative echocardiograms were available for 27 of 33 patients (82%). The LVEF improved to a mean of 0.55 ± 0.08 (95% confidence interval, 0.51 to 0.58; p < 0.001). Of the 11 patients with New York Heart Association Functional Classification III/IV symptoms, 8 patients were in class I/II at the last follow-up (p = 0.02). CONCLUSIONS: Restoration of sinus rhythm with the Cox-Maze IV was associated with significant improvement in the LVEF in patients with AF and TIC. This retrospective study illustrates the efficacy of the Cox-Maze IV in this patient population both at restoring sinus rhythm and improving ventricular function. Patients with TIC and poor left ventricular function in whom other treatments have failed should be strongly considered for surgical ablation.

The Cox-maze IV procedure in its second decade: still the gold standard?

Atrial fibrillation (AF) is the most common cardiac arrhythmia and the treatment options include medical treatment and catheter-based or surgical interventions. AF is a major cause of stroke, and its prevalence is increasing. The surgical treatment of AF has been revolutionized over the past 2 decades through surgical innovation and improvements in endoscopic imaging, ablation technology and surgical instrumentation. The Cox-maze (CM) procedure, which was developed by James Cox and introduced clinically in 1987, is a procedure in which multiple incisions are created in both the left and the right atria to eliminate AF while allowing the sinus impulse to reach the atrioventricular node. This procedure became the gold standard for the surgical treatment of AF. Its latest iteration is termed the CM IV and was introduced in 2002. The CM IV replaced the previous cut-and-sew method (CM III) by replacing most of the incisions with a combination of bipolar radiofrequency and cryoablation. The use of ablation technologies, made the CM IV technically easier, faster and more amenable to minimally invasive approaches. The aims of this article are to review the indications and preoperative planning for the CM IV, to describe the operative technique and to review the literature including comparisons of the CM IV with the previous cut-and-sew method. Finally, this review explores future directions for the surgical treatment of patients with AF.

Minimally Invasive Versus Full-Sternotomy Septal Myectomy for Hypertrophic Cardiomyopathy.

OBJECTIVE: Septal myectomy remains the criterion standard for the treatment of patients with hypertrophic obstructive cardiomyopathy refractory to medical therapy. There have been few reports of minimally invasive approaches. This study compared a minimally invasive septal myectomy performed at our institution with the traditional full-sternotomy approach. METHODS: Patients receiving a stand-alone septal myectomy were retrospectively reviewed from November 1999 to December 2016 (N = 120). Patients were stratified by surgical approach: traditional full sternotomy (n = 34) and ministernotomy (n = 86). Preoperative and perioperative variables were compared as well as follow-up symptomatic and echocardiographic outcomes. RESULTS: Both groups had a significant decrease in New York Heart Association class heart failure symptoms (P < 0.001). At a mean ± SD follow-up time of 2.0 ± 3.4 years, postoperative New York Heart Association class distribution was similar between ministernotomy and full sternotomy (P = 0.684). Follow-up resting left ventricular outflow tract gradient was also similar between ministernotomy and full sternotomy (11 mm Hg ± 15 vs 9 mm Hg ± 13, P = 0.381). Perioperatively, ministernotomy was not significantly different from full sternotomy in median cardiopulmonary bypass time (81 minutes vs 78 minutes, P = 0.101) but had a slightly longer median cross-clamp time (39 minutes vs 35 minutes, P = 0.017). Major complications were similar in the two groups. There was one 30-day mortality in the full-sternotomy group, but no in-hospital deaths. CONCLUSIONS: Septal myectomy performed using a minimally invasive approach has similar outcomes to the criterion standard operation done through a full sternotomy. It represents a feasible option for patients with hypertrophic obstructive cardiomyopathy unresponsive to medications.

Performance of the Cox-maze IV procedure is associated with improved long-term survival in patients with atrial fibrillation undergoing cardiac surgery.

OBJECTIVE: Atrial fibrillation (AF) is associated with an increased mortality risk. The Cox-maze IV procedure (CM4) performed concomitantly with other cardiac procedures has been shown to be effective for restoring sinus rhythm. However, few data have been published on the late survival of patients undergoing a concomitant CM4. METHODS: Patients undergoing cardiac surgery were retrospectively reviewed from 2001 to 2016 (n = 10,859). Patients were stratified into 3 groups: patients with a history of AF receiving a concomitant CM4 (CM4; n = 438), patients with a history of AF unaddressed during surgery (Untreated AF; n = 1510), and patients without AF history (No AF; n = 8911). Propensity score matching was conducted between the CM4 and Untreated AF groups, and between the CM4 and No AF groups. RESULTS: Thirty-day mortality was similar between the matched groups. Kaplan-Meier analysis showed greater survival for CM4 compared to Untreated AF (P = .004). Ten-year survival was 62% for CM4 and 42% for Untreated AF. Adjusted hazard ratio was 0.47 (95% confidence interval, 0.26-0.86, P = .014). No difference in survival was found between CM4 and No AF groups with the Kaplan-Meier analysis (P = .847). Ten-year survival was 63% for CM4 and 55% for No AF. Adjusted hazard ratio was 1.03 (95% confidence interval, 0.51-2.11, P = .929). CONCLUSIONS: For selected patients with a history of AF undergoing cardiac surgery, concomitant CM4 did not add significantly to postoperative morbidity or mortality and was associated with improved late survival compared with patients with untreated AF and a similar survival to patients without a history of AF.

The hemodynamic and atrial electrophysiologic consequences of chronic left atrial volume overload in a controllable canine model.

OBJECTIVE: The purpose of this study was to determine the effects of chronic left atrial volume overload on atrial anatomy, hemodynamics, and electrophysiology using a titratable left ventriculoatrial shunt in a canine model. METHODS: Canines (n = 16) underwent implantation of a shunt between the left ventricle and the left atrium. Sham animals (n = 8) underwent a median sternotomy without a shunt. Atrial activation times and effective refractory periods were determined using 250-bipolar epicardial electrodes. Biatrial pressures, systemic pressures, left atrial and left ventricle diameters and volumes, atrial fibrillation inducibility, and durations were recorded at the initial and at 6-month terminal study. RESULTS: Baseline shunt fraction was 46% ± 8%. The left atrial pressure increased from 9.7 ± 3.5 mm Hg to 13.8 ± 4 mm Hg (P < .001). At the terminal study, the left atrial diameter increased from a baseline of 2.9 ± 0.05 cm to 4.1 ± 0.6 cm (P < .001) and left ventricular ejection fraction decreased from 64% ± 1.5% to 54% ± 2.7% (P < .001). Induced atrial fibrillation duration (median, range) was 95 seconds (0-7200) compared with 0 seconds (0-40) in the sham group (P = .02). The total activation time was longer in the shunt group compared with the sham group (72 ± 11 ms vs 62 ± 3 ms, P = .003). The right atrial and not left atrial effective refractory periods were shorter in the shunt compared with the sham group (right atrial effective refractory period: 156 ± 11 ms vs 141 ± 11 ms, P = .005; left atrial effective refractory period: 142 ± 23 ms vs 133 ± 11 ms, P = .35). CONCLUSIONS: This canine model of mitral regurgitation reproduced the mechanical and electrical remodeling seen in clinical mitral regurgitation. Left atrial size increased, with a corresponding decrease in left ventricle systolic function, and an increased atrial activation times, lower effective refractory periods, and increased atrial fibrillation inducibility. This model provides a means to understand the remodeling by which mitral regurgitation causes atrial fibrillation.

Long-Term Survival Prediction for Coronary Artery Bypass Grafting: Validation of the ASCERT Model Compared With The Society of Thoracic Surgeons Predicted Risk of Mortality.

BACKGROUND: The recently developed American College of Cardiology Foundation-Society of Thoracic Surgeons (STS) Collaboration on the Comparative Effectiveness of Revascularization Strategy (ASCERT) Long-Term Survival Probability Calculator is a valuable addition to existing short-term risk-prediction tools for cardiac surgical procedures but has yet to be externally validated. METHODS: Institutional data of 654 patients aged 65 years or older undergoing isolated coronary artery bypass grafting between 2005 and 2010 were reviewed. Predicted survival probabilities were calculated using the ASCERT model. Survival data were collected using the Social Security Death Index and institutional medical records. Model calibration and discrimination were assessed for the overall sample and for risk-stratified subgroups based on (1) ASCERT 7-year survival probability and (2) the predicted risk of mortality (PROM) from the STS Short-Term Risk Calculator. Logistic regression analysis was performed to evaluate additional perioperative variables contributing to death. RESULTS: Overall survival was 92.1% (569 of 597) at 1 year and 50.5% (164 of 325) at 7 years. Calibration assessment found no significant differences between predicted and actual survival curves for the overall sample or for the risk-stratified subgroups, whether stratified by predicted 7-year survival or by PROM. Discriminative performance was comparable between the ASCERT and PROM models for 7-year survival prediction (p < 0.001 for both; C-statistic = 0.815 for ASCERT and 0.781 for PROM). Prolonged ventilation, stroke, and hospital length of stay were also predictive of long-term death. CONCLUSIONS: The ASCERT survival probability calculator was externally validated for prediction of long-term survival after coronary artery bypass grafting in all risk groups. The widely used STS PROM performed comparably as a predictor of long-term survival. Both tools provide important information for preoperative decision making and patient counseling about potential outcomes after coronary artery bypass grafting.

Minimally Invasive Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy.

Surgical septal myectomy is the treatment of choice for patients with symptomatic hypertrophic obstructive cardiomyopathy refractory to medications. This report describes our minimally invasive approach for performing a septal myectomy via a ministernotomy that has been used at our institution for more than a decade. In particular, patient preparation, surgical technique, and clinical considerations are highlighted. Performed properly, this minimally invasive technique is a feasible and effective approach in our experience.

Evaluation of a Novel Cryoprobe for Atrial Ablation in a Chronic Ovine Model.

PURPOSE: Cryoablation is used in the treatment of atrial fibrillation and other cardiac arrhythmias. This study evaluated a novel 10-cm flexible nitrous oxide cryoprobe in an ovine model of atrial ablation. DESCRIPTION: Six sheep were anesthetized, underwent a left thoracotomy, and were placed on cardiopulmonary bypass. A left atriotomy was performed, and the cryoprobe was applied endocardially for 120 seconds at less than -40°C to 4 sites on the left atrium. The atrium was closed and the animals were allowed to recover. After 30 days, the animals were euthanized. Transmurality was evaluated in 5-mm sections of each lesion using 2,3,5-triphenyltetrazolium chloride (TTC) and Masson's trichrome staining. EVALUATION: All animals survived. One hundred four of 106 sections (98%) were transmural by TTC; 103 of 106 (97%) sections were transmural by trichrome staining. There was no late atrial perforation, intraluminal thrombus, or thromboembolism. CONCLUSIONS: The device reliably produced transmural lesions in a chronic ovine model. Its performance was equivalent to that of other nitrous oxide cryoablation systems.