Andreas Zierer

A New Era in the Surgical Treatment of Atrial Fibrillation: The Impact of Ablation Technology and Lesion Set on Procedural Efficacy

Background/Objective:While the Cox-Maze procedure remains the gold standard for the surgical treatment of atrial fibrillation (AF), the use of ablation technology has revolutionized the field. To simplify the procedure, our group has replaced most of the incisions with bipolar radiofrequency ablation lines. The purpose of this study was to examine results using bipolar radiofrequency in 130 patients undergoing a full Cox-Maze procedure, a limited Cox-Maze procedure, or pulmonary vein isolation alone. Methods:A retrospective review was performed of patients who underwent a Cox-Maze procedure (n = 100), utilizing bipolar radiofrequency ablation, a limited Cox-Maze procedure (n = 7), or pulmonary vein isolation alone (n = 23). Follow-up was available on 129 of 130 patients (99%). Results:Pulmonary vein isolation was confirmed by intraoperative pacing in all patients. Cross-clamp time in the lone Cox-Maze procedure patients was 44 ± 21 minutes, and 104 ± 42 minutes for the Cox-Maze procedure with a concomitant procedure, which was shortened considerably from our traditional cut-and-sew Cox-Maze procedure times (P < 0.05). There were 4 postoperative deaths in the Cox-Maze procedure group and 1 in the pulmonary vein isolation group. The mean follow-up was 13 ± 10, 23 ± 15, and 9 ± 10 months for the Cox-Maze IV, the pulmonary vein isolation, and the limited Cox-Maze procedure groups, respectively. At last follow-up, freedom from AF was 90% (85 of 94), 86% (6 of 7), and 59% (10 of 17) in the in the Cox-Maze procedure group, limited Cox-Maze procedure group, and pulmonary vein isolation alone group, respectively. Conclusions:The use of bipolar radiofrequency ablation to replace Cox-Maze incisions was safe and effective at controlling AF. Pulmonary vein isolation alone was much less effective, and should be used cautiously in this population.

Isolating the entire posterior left atrium improves surgical outcomes after the Cox maze procedure.

OBJECTIVES The importance of each ablation line in the Cox maze procedure for treatment of atrial fibrillation remains poorly defined. This study evaluated differences in surgical outcomes of the procedure performed either with a single connecting lesion between the right and left pulmonary vein isolations versus 2 connecting lesions (the box lesion), which isolated the entire posterior left atrium. METHODS Data were collected prospectively on 137 patients who underwent the Cox maze procedure from April 2002 through September 2006. Before May 2004, the pulmonary veins were connected with a single bipolar radiofrequency ablation lesion (n = 56), whereas after this time, a box lesion was routinely performed (n = 81). The mean follow-up was 11.8 +/- 9.6 months. RESULTS The incidence of early atrial tachyarrhythmia was significantly higher in the single connecting lesion group compared with that in the box lesion group (71% vs 37%, P < .001). The overall freedom from atrial fibrillation recurrence was significantly higher in the box lesion group at 1 (87% vs 69%, P = .015) and 3 (96% vs 85%, P = .028) months. The use of antiarrhythmic drugs was significantly lower in the box lesion group at 3 (35% vs 58%, P = .018) and 6 (15% vs 44%, P = .002) months. CONCLUSIONS Isolating the entire posterior left atrium by creating a box lesion instead of a single connecting lesion between the pulmonary veins showed a significantly lower incidence of early atrial tachyarrhythmias, higher freedom from atrial fibrillation recurrence at 1 and 3 months, and lower use of antiarrhythmic drugs at 3 and 6 months. A complete box lesion should be included in all patients undergoing the Cox maze procedure.

Selective antegrade cerebral perfusion and mild (28°C-30°C) systemic hypothermic circulatory arrest for aortic arch replacement: results from 1002 patients.

OBJECTIVES The use of selective antegrade cerebral perfusion (ACP) makes deep hypothermia nonessential for aortic arch replacement. Consequently, a growing tendency to increase the body temperature during circulatory arrest with ACP has recently been reported from various institutions. However, very little is known about the clinical effect of different modes of ACP (unilateral vs bilateral) on neurologic morbidity. Also, the safe limits of this approach for spinal chord and visceral organ protection are yet to be defined. METHODS Between January 2000 and January 2011, 1002 consecutive patients underwent aortic arch repair during ACP (unilateral, 673; bilateral, 329) with mild systemic hypothermia (30°C ± 2°C; range, 26°-34°C) at 2 centers in Germany. The mean patient age was 62 ± 14 years, 663 patients (66%) were men, and 347 patients (35%) had acute type A dissection. Hemiarch replacement was performed in 684 patients (68%), and 318 (32%) underwent total arch replacement. RESULTS The cardiopulmonary bypass time accounted for 158 ± 56 minutes and the myocardial ischemic time, 101 ± 41 minutes. Isolated ACP was performed for 36 ± 19 minutes (range, 9-135). We observed new postoperative permanent neurologic deficits in 28 patients (3%; stroke in 25 and paraplegia in 3) and transient neurologic deficits in 42 patients (4%). All 3 cases of paraplegia occurred in patients with acute type A dissection and a broad range of ACP times (24, 41, and 127 minutes). A trend was seen toward a reduced permanent neurologic deficit rate after unilateral ACP (P = .06), but no difference was seen in the occurrence of transient neurologic deficits (P = .6). Overall, the early mortality rate was 5% (n = 52). Temporary dialysis was necessary primarily after surgery in 38 patients (4%). When corrected for the unequal distribution of type A dissection, neurologic morbidity, early mortality, and the need for temporary dialysis were independent of the duration of ACP and were not affected by unilateral versus bilateral ACP. CONCLUSIONS Current data suggest that ACP and mild systemic hypothermic circulatory arrest can be safely applied to complex aortic arch surgery even in a subgroup of patients with up to 90 minutes of ACP. Unilateral ACP offers at least equal brain and visceral organ protection as bilateral ACP and might be advantageous in that it reduces the incidence of embolism arising from surgical manipulation on the arch vessels.

The transapical approach for aortic valve implantation.

OBJECTIVE Percutaneous aortic valve implantation has been performed clinically in high-risk patients with severe aortic stenosis. Transfemoral retrograde valve delivery is limited by concomitant peripheral vascular disease and the size of the delivery system. We report on the alternative transapical approach that allows accurate antegrade placement of a catheter-deliverable aortic valve. METHODS Over a 2-year period, 26 consecutive patients (84.3 +/- 6.5 years) were treated at our center. Transapical aortic valve implantation was performed with 23-mm and 26-mm pericardial valves (Cribier-Edwards; Edwards Lifesciences, Irvine, Calif) mounted on a stainless steel stent. A limited anterolateral incision, in the fifth intercostal space, was used to access the apex of the heart. The valve was crimped, placed into a 24F sheath, and introduced into the left ventricle through purse-string sutures. Fluoroscopy and transesophageal echocardiography were used to guide the catheter across the native valve and to direct deployment of the stent at the level of the annulus. During deployment, the heart was unloaded with extracorporeal support or with rapid ventricular pacing. The average logistic EuroSCORE-predicted risk for mortality was 36.5% +/- 5.8%. RESULTS All valves were successfully deployed at the target. On echocardiography, all valves showed good hemodynamic function with only minor paravalvular leakages. The mean transaortic valve gradient was 6 +/- 2 mm Hg. Thirty-day mortality was 15% (n = 4). One patient died of perforation of the right ventricle and 1 of dissection of the aortic root. There were 2 cases of conversion to open surgery. In 2 patients, the left main stem was partially obstructed by the native valve and required stent angioplasty. CONCLUSIONS Initial results of the transapical approach are encouraging. Long-term studies and randomized protocols will be required to further evaluate this procedure.

Antegrade Cerebral Perfusion With Mild Hypothermia for Aortic Arch Replacement: Single-Center Experience in 245 Consecutive Patients

BACKGROUND Aortic arch replacement remains a surgical challenge because of prolonged operative times, bleeding complications, and a considerable risk of neurologic morbidity and mortality. This study investigates our clinical results after modification of perfusion technique for cardiopulmonary bypass as well as temperature management for these high- risk patients. METHODS Between January 2000 and January 2009, 245 consecutive patients underwent aortic arch repair during selective antegrade cerebral perfusion (ACP) with mild systemic hypothermia (30.5°C±1.4°C). Mean age was 63±12 years, 175 patients (71%) were men and 141 patients (58%) had acute type A dissection. Hemiarch replacement was performed in 152 patients (62%) while the remaining 93 patients (38%) underwent total arch replacement. RESULTS Cardiopulmonary bypass time accounted for 168±62 minutes, and myocardial ischemic time was 103±45 minutes. Isolated ACP was performed for 38±27 (range 12 to 135) minutes. Chest tube drainage during the first 24 hours was 563±248 mL. Mean ventilation time was 44±22 hours. Serum lactate levels at 1, 12, and 24 hours postoperatively rose to 19±11, 33±14, and 20±8 mg/dL, respectively. We observed new postoperative permanent neurologic deficits in 14 patients (6%) and transient neurologic deficits in 12 patients (5%). The operative mortality rate was 8% (n=20). Among patients with ACP times 60 minutes or greater (n=28; 92±29 minutes), permanent neurologic deficits occurred in 2 individuals (n=2 of 28; 7%) and operative mortality was 7% (n=2 of 28). At late follow-up (3.8±3.2 years, 98% complete), 196 patients (80%) were still alive. CONCLUSIONS Selective ACP in combination with mild hypothermia offered sufficient cerebral as well as distal organ protection in our patient cohort. Thus, current data suggest that this standardized perfusion and temperature management protocol can safely be applied to complex aortic arch surgery requiring up to 90 minutes of isolated ACP times.

Atrial fibrillation propagates through gaps in ablation lines: Implications for ablative treatment of atrial fibrillation

BACKGROUND It has been hypothesized that atrial lesions must be transmural to successfully cure atrial fibrillation (AF). However, ablation lines often do not extend completely across the atrial wall. OBJECTIVE The purpose of this study was to determine the effect of residual gaps on conduction properties of atrial tissue. METHODS Canine right atria (n = 13) were isolated, perfused, and mounted on a 250-lead electrode plaque. The atria were divided with a bipolar radiofrequency ablation clamp, leaving a gap that was progressively narrowed. Conduction velocities at varying pacing rates and AF frequencies were measured before and after ablations. AF was induced with an extra stimulus and acetylcholine. RESULTS Gap widths from 11.2 to 1.1 mm were examined. Conduction velocities through gaps were dependent cycle length (P = .002) and gap size (P <.001). Overall, 253 (97%) of a total of 260 gaps allowed paced propagation; 51 (91%) of 56 gaps 1-3 mm in width permitted paced propagation, as did 202 (99%) of 204 gaps >or=3.0 mm. Similarly, 253 (97%) of a total of 260 gaps allowed propagation of AF. For AF, 51 (93%) of 55 gaps 1-3 mm allowed AF to pass through, as did 202 (99%) of 205 gaps >or=3.0 mm. Gaps as small as 1.1 mm conducted paced and AF impulses. CONCLUSIONS Conduction velocities were slowed through residual gaps. However, propagation of wave fronts during pacing and AF occurred through the majority of residual gaps, down to sizes as small as 1.1 mm. Leaving viable tissue in ablation lines for the treatment of AF could account for failures.

Antegrade Cerebral Perfusion for Acute Type A Aortic Dissection in 120 Consecutive Patients

BACKGROUND Treatment of acute type A aortic dissection remains a surgical challenge because of prolonged operative times, bleeding complications, and a considerable risk of neurologic morbidity and mortality. The following study investigates clinical results after modification of perfusion technique for cardiopulmonary bypass as well as temperature management. METHODS Between January 2000 and August 2006, 120 consecutive patients underwent repair of acute type A dissection. Selective antegrade cerebral perfusion through the right subclavian artery combined with mild systemic hypothermia (30 degrees C) was used in all patients. RESULTS Mean cardiopulmonary bypass time was 144 +/- 53 minutes, and mean myocardial ischemic time was 98 +/- 49 minutes. Isolated cerebral perfusion was performed for 25 +/- 12 minutes. Mean core temperature amounted to 30.1 degrees +/- 2.2 degrees C. Chest tube drainage during the first 24 hours was 525 +/- 220 mL. Mean ventilation time was 54 +/- 22 hours. Elevation of serum lactate levels at 1, 12, and 24 hours postoperatively rose to 22 +/- 14, 18 +/- 11, and 19 +/- 8 mg/dL respectively. We observed new postoperative permanent neurologic deficits in 5 patients (4.2%) and TND in 3 patients (2.5%). The 30-day mortality rate was 5% (n = 6). After a mean follow-up period of 2.8 years, 104 patients (87%) were still alive. CONCLUSIONS Antegrade cerebral perfusion in combination with mild hypothermia offered sufficient neurologic protection in our patient cohort, provided adequate distal organ protection, and reduced perioperative complications in surgery for type A dissection. This perfusion strategy may help in reducing perioperative complications in this particular patient population.

Is transapical aortic valve implantation really less invasive than minimally invasive aortic valve replacement

BACKGROUND Transcatheter valve implants currently draw their justification for use from reduction of perioperative risk. However, patient age and comorbidities are independent predictors of adverse outcome after aortic valve replacement, regardless of surgical approach. Therefore, it is unclear whether transapical aortic valve implantation really improves outcomes in high-risk patients. METHODS We included a total of 51 high-risk patients with severe aortic valve stenosis. Patients were allocated to transapical aortic valve implantation (n = 21) or minimally invasive aortic valve replacement via a partial upper sternotomy (n = 30), in a nonrandomized fashion. Patient age, preoperative comorbidities, and perioperative risk, expressed as logistic EuroSCORE (38% +/- 14% vs 35% +/- 9%), were matched between the 2 groups. RESULTS Early morbidity and mortality were comparable between groups, but transapical aortic valve implantation was associated with shorter operative time (P = .004), ventilation time (P < .001), intensive care unit stay (P < .001), and hospital stay (P < .001). Thirty-day mortality was 14% (n = 3) in the transcatheter group versus 10% (n = 3) in the surgical group. After a mean follow-up of 12 +/- 4 months (100% complete), there were a total of 5 (24%) deaths in the transapical group versus 5 (17%) deaths in the open surgery group. There was 1 intraoperative death in the transapical group versus none in the surgery group. In the transapical group, there were 2 re-explorations for bleeding, 2 intraoperative conversions, 1 case of prosthesis migration, and 2 impairments of coronary arteries. The surgery group included 1 re-exploration, 1 stroke, 1 pacemaker implantation for complete atrioventricular block, and 3 cases of atrial fibrillation. CONCLUSIONS Current data suggest a faster postoperative recovery after transapical aortic valve implantation, with early and late morbidity and mortality comparable with those of minimally invasive aortic valve replacement via partial upper sternotomy.

Long-Term Results After Surgical Repair of Postinfarction Ventricular Septal Rupture by Infarct Exclusion Technique

BACKGROUND Ventricular septal defect (VSD) is one of the most serious and life-threatening complications of acute myocardial infarction. The aim of this study was to evaluate the early and long-term results of the patients after surgical repair of postinfarction VSD by infarct exclusion technique. METHODS A total of 32 consecutive patients (mean age, 62.5 +/- 10.5 years) underwent postinfarction VSD repair using a standardized technique in our department. A retrospective analysis of clinical and operative data, predictors of early mortality, and long-term survival was performed. The localization of VSD was posterior in 50% and anterior in 50% of the patients. RESULTS The hospital mortality was 31.2% (10 patients). The most common cause of hospital death was persistent low cardiac output. The mortality of the posterior VSD group was significantly lower than that of the anterior VSD group (18.7% and 43.7%, respectively, p = 0.01). Intra-aortic balloon pump support and absence of cardiac shock were significantly associated with a lower risk of hospital mortality (p = 0.0001 and p = 0.0009, respectively). The actuarial survival rates of in-hospital survivors at 5 and 10 years were 79% +/- 2% and 51% +/- 3%, respectively. CONCLUSIONS The repair of postinfarction VSD by the infarct exclusion is feasible and safe. This technique seems to offer sufficient favorable early and long-term results compared with other techniques. Early indication, preoperative intra-aortic balloon pump support may improve the surgical results. Preoperative cardiogenic shock carries a poor prognosis for this patient group.

Importance of Blood Pressure Control After Repair of Acute Type A Aortic Dissection: 25-Year Follow-Up in 252 Patients

The purpose of this study was to evaluate factors that impact outcome following repair of type A aortic dissection. Over 25 years (1984–2009), 252 patients underwent repair of acute type A dissection. Mean follow‐up for reoperation or death was 6.9±5.9 years. Operative mortality was 16% (41 of 252). Multivariate analysis identified one risk factor for operative death: presentation malperfusion (P=.003). For operative survivors, 5‐, 10‐, and 20‐year survival was 78%±3%, 59%±4%, and 24%±6%, respectively. Late death occurred earlier in patients with previous stroke (P=.02) and chronic renal insufficiency (P=.007). Risk factors for late reoperation included male sex (P=.006), Marfan syndrome (P<.001), elevated systolic blood pressure (SBP, P<.001), and absence of β‐blocker therapy (P<.001). Kaplan‐Meier analysis demonstrated at 10‐year follow‐up that patients who maintained SBP <120 mm Hg had improved freedom from reoperation (92±5%) compared with those with SBP 120 mm Hg to 140 mm Hg (74%±7%) or >140 mm Hg (49%±14%, P<.001). At 10‐year follow‐up, patients on β‐blocker therapy experienced 86%±5% freedom from reoperation compared with only 57%±11% for those without (P<.001). Operative survival was decreased with preoperative malperfusion. Long‐term survival was dependent on comorbidities but not operative approach. Reoperation was markedly increased in patients not on β‐blocker therapy and decreased with improved SBP control. Strict control of hypertension with β‐blocker therapy is warranted following repair of acute type A dissection.