Matthew R. Schill

Late results of the Cox-maze IV procedure in patients undergoing coronary artery bypass grafting

Objective: Most patients with atrial fibrillation (AF) undergoing cardiac surgery do not receive concomitant ablation. This study reviewed outcomes of patients with AF undergoing Cox‐maze IV (CMIV) procedure with radiofrequency and cryoablation and coronary artery bypass grafting (CABG) at our institution. Methods: Between the introduction of radiofrequency ablation in 2002 and 2015, 135 patients underwent left‐ or biatrial CMIV with CABG. Patients undergoing other cardiac procedures, except mitral valve repair, or who had emergent, reoperative, or off‐pump procedures were excluded. Eighty‐three patients remained in the study group after exclusion criteria were applied. Freedom from atrial tachyarrhythmias (ATAs) was ascertained using electrocardiogram, Holter monitor, or pacemaker interrogation at 1 to 5 years postoperatively. Results: Operative mortality was 3%. Freedom from ATAs at 1 year in the CMIV group was 98%, with 88% off antiarrhythmia drugs. Freedom from ATAs and antiarrhythmia drugs was 70% at 5 years. Conclusions: The addition of CMIV to CABG resulted in excellent freedom from ATAs at 1 to 5 years. These patients are at increased risk for nonfatal complications compared with others undergoing concomitant surgical ablation.

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.

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.

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 Massons 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.

Fundamentals of Laparoscopic Surgery: Not Only for Senior Residents

OBJECTIVE Fundamentals of laparoscopic surgery (FLS) was developed by the Society of American Gastrointestinal and Endoscopic Surgeons to teach the physiology, fundamental knowledge, and technical skills required for basic laparoscopic surgery. We hypothesize that residents are doing more laparoscopic surgery earlier in residency, and therefore would benefit from an earlier assessment of basic laparoscopic skills. Here, we examine FLS test results and ACGME case logs to determine whether it is practical to administer FLS earlier in residency. DESIGN FLS test results were reviewed for the 42 residents completing FLS between July 2011 and July 2016. ACGME case logs for current and former residents were reviewed for laparoscopic cases logged by each postgraduate year. Basic and complex laparoscopic cases were determined by ACGME General Surgery Defined Category and Minimums Report. Descriptive statistics were used for analysis. SETTING Academic general surgery residency, Washington University in St. Louis School of Medicine. PARTICIPANTS Current and former general surgery residents. RESULTS A total of 42 residents took and passed FLS between July 2011 and July 2016. All residents successfully passed the FLS knowledge and skills examinations on the first attempt regardless of their postgraduate year (PGY 3n = 13, PGY 4n = 15, and PGY 5n = 14). Total laparoscopic case volume has increased over time. Residents who graduated in 2012 or 2013 completed 229 laparoscopic cases compared to 267 laparoscopic cases for those who graduated from 2014 to 2016 (p = 0.02). Additionally, current residents completed more laparoscopic cases in the first 2 years of residency than residents who graduated from 2012 to 2016 (median current = 38; former = 22; p < 0.001). Examining laparoscopic case numbers for current residents by PGY demonstrated that the number of total and complex laparoscopic cases increased in each of the first 3 years of residency with the largest increase occurring between the PGY 2 and PGY 3 years. In the PGY 4 and PGY 5 years, most laparoscopic cases were complex. CONCLUSION Increased use of laparoscopic surgery has led to a corresponding increase in laparoscopic case volume among general surgery residents. We would advocate for FLS testing to serve as an early assessment of laparoscopic knowledge and skill and should be performed before a significant increase in complex laparoscopic surgery during training.

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.