[Long-term Outcomes of the Maze Procedure Omitting the Ablation Line to The Superior Vena Cava].

OBJECTIVE: In an effort to avoid postoperative sick sinus syndrome( SSS), we omit the ablation line to the superior vena cava( SVC) in the Cox-mazeⅢ lesion set. We report the long-term outcomes, including the freedom from SSS. METHODS: We studied 102 patients who underwent bi-atrial maze procedure for persistent atrial fibrillation (Af) from 2009 through 2023. Bipolar radio frequency ablation or cryoablation was used except for right-side atriotomy and right atriotomy. Cryoablation was used for atrioventricular annulus. The patient age was 68±9.4. Duration of Af was 3.4±6.5 years (unknown 9 cases). The amplitude of f-wave in V1 was 0.182±0.095 mV and it was<0.1 mV in 19 (18.6%). Diameter of the left atrium was 50±8.9 mm, and left atrial volume index was 89±37 ml/m2. Ninety-one (89.2%) patients underwent concomitant mitral valve surgery. RESULTS: Survival rate was 99% at 1 year and 96% at 5 years. Freedom from Af was 92% at 1 year and 88% at 5 years. Freedom from permanent pacemaker implantation (PPI) was 87% at 1 year and 83% at 5 years. CONCLUSIONS: Defibrillation rate and the incidence of PPI was comparable to those in previous reports after standard Cox-mazeⅢ. SSS after maze for persistent Af seem due to patient.

[Prevention and Treatment of Ischemic Spinal Cord Injury].

In recent years, the widespread use of thoracic/thoracoabdominal stent grafting and a better understanding of spinal cord blood supply have led to quite a few change in measures to prevent spinal cord injury. It is essential to understand the characteristics of spinal cord blood flow, which is complicated by collateral pathways, and to strive to maintain spinal cord blood flow during surgery. It is also important to plan staged repair as much as possible in any treatment modality. Particular attention must be paid to the prevention of second attacks, especially after thoracic/thoracoabdominal endovascular aortic repair without segmental artery reconstruction. Systemic circulatory and respiratory management, improvement of anemia, and cerebrospinal fluid drainage with attention to drainage rates, may be effective as preventive and therapeutic measures for spinal cord injury.

Internal circular suture annuloplasty for aortic valve repair.

Stabilizing the aorto-ventricular junction is integral in aortic valve repair. We report our technique of internal circular suture annuloplasty. We used a continuous horizontal mattress suture of a single thick expanded polytetrafluoroethylene suture (CV-3). We put 4 stitches per sinus, so the suture was below the cusp attachment line at the nadirs and passed through the interleaflet triangle at the upper aorto-ventricular junction level. The suture was reinforced with pericardial pledgets on both sides of each commissure. We used this technique in 12 patients. The diameter of aorto-ventricular junction was reduced from 25 ± 2 mm to 22 ± 1 mm (n = 11) and was 22 ± 1 mm at the latest follow-up (4-74 months, median 41, n = 10). In 2 patients with large aorto-ventricular junction (27 mm or more), expected annular reduction was not achieved. Our modified technique is simple and seems durable. It may be useful for mild annular dilatation.

Surgical Approaches to Single-Stage Extended Aortic Repair from the Ascending to the Distal Descending Aorta.

Single-stage extended replacement from the ascending to the distal descending aorta or beyond is a formidable operation that should be preserved for those who have no other option or those who are physically fit, and should be performed in the experienced centers. Hybrid operations combining open surgical repair with thoracic endovascular aortic repair through a median sternotomy incision are preferable because these operations are less invasive than the extended open aortic repair and the risk of spinal cord ischemia is lower compared with the frozen elephant trunk operation. However, these operations are associated with the inherent demerits of endovascular aneurysm exclusion. When the underlying aortic pathology necessitates extended open aortic repair in a single stage, approaches such as the anterolateral partial sternotomy, straight incision with rib cross, and extended thoracotomy with sternal transection may be useful to provide sufficient exposure for both aortic reconstruction and organ protection, with less surgical stress to the patients.

Patency of separate tube grafts for intercostal artery reconstruction: Size and length matter.

OBJECTIVES: Low patency is a major concern when using separate tube grafts for intercostal artery reconstruction. Our goal was to elucidate the optimal size and length of grafts from their patency and the computational fluid dynamics (CFD). METHODS: The patency, size and length of separate tube grafts were evaluated in 41 patients. Simulation of CFD was performed in a model derived from a patient with a patent 12-mm graft that was 15 mm long, with 2 simulation models with a smaller (8-mm) or longer (30-mm) graft. RESULTS: A total of 49 grafts were used for intercostal artery reconstruction. There was 1 in-hospital death and 2 spinal cord injuries. The patency rate, which could be evaluated in 46 grafts, was 63% (29/46). It was 71% (24/34) in thoracoabdominal aortic replacement and 42% (5/12) in descending aortic replacement. Among 14 patients in whom all grafts were occluded, no patients developed spinal cord injury. All grafts longer than 25 mm were occluded (n = 5). Eight- and 10-mm grafts showed better patency than 12-mm grafts in thoracoabdominal aortic replacement (P = 0.008) when grafts were shorter than 25 mm. Simulation of CFD revealed vortical flow within the 12-mm graft, which did not reach the intercostal orifice, whereas helical flow was maintained throughout the cardiac cycle within the 8-mm graft. CONCLUSIONS: Eight- and 10-mm grafts seemed better than 12-mm grafts, and grafts should be kept shorter than 25 mm. Simulation of CFD may shed light on the issue of the optimal intercostal artery reconstruction technique.

Radial artery vs saphenous vein grafts for sequential coronary bypass grafting as a second conduit for the left coronary territory.

OBJECTIVE: Although the radial artery graft has an adaptive property to flow demand, its flow characteristics in aorto-coronary sequential bypass grafting are not well elucidated. We evaluated the differences between the vein and radial artery grafts in the patency and the transit time flow meter-derived parameters (flow and pulsatile index), according to the stenosis rate of terminal target vessels and the number of anastomoses, in sequential bypass grafting to the left coronary territories as a second conduit. METHODS: We analyzed 222 patients who underwent isolated on-pump beating coronary artery bypass grafting with an aorto-coronary bypass to the left coronary territory. The patients were divided into radial artery group (n = 154) and vein graft group (n = 68). Sequential bypass was performed 1n 171 patients (127 radial arteries, 44 veins). RESULTS: Flow of the radial artery grafts was lower than that of the vein grafts (40.9 ± 22.3 vs 47.5 ± 23.8 mL/min, p = 0.044), while it became higher as the number of anastomoses per graft increased (1: 28.9 ± 16.3 vs 2: 40.9 ± 19.9 vs 3: 55.8 ± 27.5, p < 0.001). The patency of radial artery grafts was better than that of vein grafts (98.0% vs 92.6%, p = 0.010; p < 0.001 after propensity score weighting). CONCLUSIONS: Although intraoperative flow rate of the radial artery graft is lower, it has sufficient flow reserve for sequential bypass grafting, and its early patency is high enough. Radial artery is suitable for sequential bypass grafting to the left coronary territories as a second arterial conduit.

18-Fluorodeoxyglucose positron emission tomography in the diagnosis of prosthetic aortic graft infection: the difference between open and endovascular repair.

OBJECTIVES: 18-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has been reported as useful for diagnosing aortic graft infection. However, 18F-FDG uptake may depend upon various factors including open versus endovascular repair and time from surgery. We aimed to elucidate the factors influencing its uptake and the diagnostic value of 18F-FDG PET/CT after open and endovascular repair. METHODS: Hospital database of PET/CT (N = 14 490) and our departmental database were cross-checked to identify those who underwent 18F-FDG PET/CT after aortic repair. Patient's data were retrieved from the chart. Images were reviewed by 2 nuclear medicine specialists in consensus, and the presence of increased 18F-FDG uptake was recorded. The maximum standardized uptake value (SUV max) was measured. RESULTS: Among the 1112 patients who underwent aortic repair between 2011 and 2022, 71 patients were identified. Eighteen patients underwent 18F-FDG PET/CT for suspected graft infection and the remaining 53 patients for other purposes (malignancy, etc.). Fourteen patients were treated as aortic graft infection. They had significantly higher SUV max than those without graft infection [mean 8.64 (standard deviation 2.78) vs 3.40 (standard deviation 0.84); P < 0.01]. In the non-infected grafts, SUV max was higher early after open surgical repair, while it remained low after endovascular repair. CONCLUSIONS: After endovascular aortic repair, a constant cut-off value of 'SUV max = 4.5' seems appropriate for diagnosing graft infection, since it remains low and stable from the early postoperative period. After open surgical repair, it seems acceptable to have 'stepwise cut-off value' depending on the time from surgery.

Etiology of renal failure influences the outcome of heart valve replacement in chronic dialysis patients.

Life expectancy of the chronic dialysis patients depends upon the underlying renal disease, but its influence on the outcome of heart valve replacement has not been studied. We aimed to elucidate the difference in the early and midterm results of heart valve replacement according to the etiology of renal diseases. We retrospectively analyzed 17 patients on chronic dialysis who underwent heart valve replacement from 2002 to October 2009. Underlying renal disease was primary in ten patients (glomerulonephritis 8, others 2) and secondary in seven (nephrosclerosis 4, diabetic nephropathy 3). Mean age was 61 ± 10 for primary and 67 ± 7 for secondary renal diseases. Mean duration of dialysis was 18 ± 6 years for primary and 9 ± 9 for secondary renal diseases (p = 0.02). In the aortic position, mechanical valves were used in 12 patients and bioprostheses in three. In the mitral position, mechanical valves were used in all four. Deep hypothermic operation was required for severe aortic calcification in five (primary 5). Mean follow up period was 23 ± 18 months. There were two in-hospital deaths in patients with primary renal disease. Three-year survival rate including hospital deaths, on the other hand, was higher for primary renal diseases (80%) than secondary ones (34%). Despite elevated perioperative risk due to consequence of longer duration of dialysis, midterm survival of patients with primary renal diseases seemed better than for those with secondary renal diseases. These results may help the choice of heart valve prosthesis in chronic dialysis patients.

Functional brain isolation technique for stroke prevention in thoracic endovascular aortic repair.

To prevent embolic stroke during thoracic endovascular aortic repair, we have adopted the brain isolation technique since June 2014 in 9 selected high-risk patients (9/134: 6.7%) having ulcerated or protruding atheromas within the proximal aorta. Cardiopulmonary bypass was used to prevent aortic atheromas from entering the brain. We used a heparin-coated closed-loop cardiopulmonary bypass system incorporating a soft reservoir bag with 1 mg/kg heparin to minimize the disadvantages of extracorporeal circulation. The bypass graft (right axillary-left carotid-left axillary) was used as an arterial inflow in patients undergoing zone-1 landing (n = 8), while peripheral cannulation into 3 brachiocephalic arteries was employed in the remaining patient. Initial pump flow was set at 1.3 l/min/m2, and native cardiac output was reduced by adjusting the reservoir bag volume. Aortography was performed to confirm non-visualization of the arch vessels before catheter manipulation. There was no mortality and 1 solitary left cerebellar infarction.

Bipolar transesophageal thoracic spinal cord stimulation: A novel clinically relevant method for motor-evoked potentials.

OBJECTIVE: Although transesophageal motor-evoked potential elicited by monopolar cervical cord stimulation is more stable and rapid in response to ischemia than transcranial motor-evoked potential in canine experiments, direct cervical alpha motor neuron stimulation precludes clinical application. We evaluated a novel stimulation method using a bipolar esophageal electrode to enable thoracic cord stimulation. METHODS: Twenty dogs were anesthetized. For bipolar transesophageal stimulation, the interelectric pole distance was set at 4 cm. Changes in amplitude in response to incremental stimulation intensity (100-600 V) were measured to evaluate stability. Spinal cord ischemia was induced by aortic balloon occlusion at the T8 to T10 level for 10 minutes to evaluate response time or at the T3 to T5 level for 25 minutes to evaluate prognostic value. Neurological function was evaluated using the Tarlov score at 24 and 48 hours postoperatively. RESULTS: Bipolar transesophageal stimulation was successful in all animals and their forelimb waveforms were identical to those after transcranial stimulation. The minimum stimulation intensity to produce >90% of the maximum amplitude was significantly lower in both monopolar and bipolar transesophageal stimulation than in transcranial stimulation (n = 5). Time to disappearance and recovery (>75%) of the hindlimb potentials were significantly shorter by both monopolar and bipolar transesophageal stimulation than by transcranial stimulation (n = 5). Correlation with neurological outcomes was comparable among all stimulation methods (n = 10). CONCLUSIONS: Motor-evoked potential can be elicited by bipolar transesophageal thoracic cord stimulation without direct cervical alpha motor neuron stimulation, and its stability and response time are comparable to those elicited by monopolar stimulation.

Clinical feasibility and safety of transoesophageal motor-evoked potential monitoring.

OBJECTIVES: Canine experiments have shown that transoesophageal motor-evoked potential monitoring is feasible, safe and stable, with a quicker response to ischaemia and a better prognostic value than transcranial motor-evoked potentials. We aimed to elucidate whether or not these findings were clinically reproducible. METHODS: A bipolar oesophageal electrode mounted on a large-diameter silicon tube and a train of 5 biphasic wave stimuli were used for transoesophageal stimulation. Results of 18 patients (median age 74.5 years, 13 males) were analysed. RESULTS: There were no mortalities, spinal cord injuries or complications related with transoesophageal stimulation. Transcranial motor-evoked potential could not be monitored up to the end of surgery in 3 patients for unknown reasons, 2 of whom from the beginning. Transoesophageal motor-evoked potential became non-evocable after manipulation of a transoesophageal echo probe in 2 patients. Strenuous movement of the upper limbs during transoesophageal stimulation was observed in 3 patients. In 14 patients who successfully completed both monitoring methods up to the end of surgery (11 thoraco-abdominal and 3 descending aortic repair), the final results were judged as false positives in 6 by transcranial stimulation and in 1 by transoesophageal stimulation. The stimulation intensity was significantly lower and the upper limb amplitude was significantly higher by transoesophageal stimulation, while the lower limb amplitude was comparable. CONCLUSIONS: Transoesophageal motor-evoked potential monitoring is clinically feasible and safe with a low false positive rate. A better electrode design is required to avoid its migration by transoesophageal echo manipulation. Further studies may be warranted. CLINICAL REGISTRATION NUMBER: UMIN000022320.

Japanese perspective in surgery for thoracoabdominal aortic aneurysms.

OBJECTIVE: Operative mortality and morbidity after thoracoabdominal aortic surgery remain high. We report our strategy and outcomes, especially those of spinal cord protection. METHODS: Outcomes of 178 patients (age: 26-88 years) who underwent thoracoabdominal aortic replacement were retrospectively analyzed. 65 had aortic dissection, 14 had infected aneurysms, and 22 presented with rupture. Operations were non-elective in 24 and redo through re-thoracotomy in 21. Extent of replacement was Crawford-I in 39, II in 26, III in 78, and IV in 35. Staged repair was recently preferred, which resulted in decrease in extent II repair and increase in redo since 2009. Operations were performed under distal aortic perfusion and multi-segmental sequential repair to maximize collateral blood flow, and deep hypothermic circulatory arrest was preserved for those requiring open aortic anastomosis (n = 20). A total of 166 separate grafts were used for intercostal reconstruction in 88 patients, which was guided by preoperative feeding artery localization. Their patency was studied by postoperative MD-CT in 74 patients for 145 grafts. RESULTS: There were 3.9% hospital mortality and 5.1% spinal cord injury. Preoperative feeding artery localization resulted in reduced number of reconstruction and improved patency, and grafts connecting to the feeding artery were patent in 92%. Results of redo operations were not different (no mortality and spinal cord injury) from the de novo operations. CONCLUSIONS: Our concept of spinal cord protection, which was based on selective intercostal reconstruction while maximizing spinal cord collateral blood flow, seems justified.

Carotid stenosis with impaired brain flow reserve is associated with an increased risk of stroke in on-pump cardiovascular surgery.

OBJECTIVES: To prevent haemodynamic stroke during cardiovascular surgery in patients with carotid stenosis, we routinely evaluated magnetic resonance angiography and selectively evaluated brain perfusion single-photon emission computed tomography with acetazolamide challenge. Off-pump surgery was preferred when cerebral blood flow reserve was impaired. This strategy's usefulness was investigated. METHODS: Among the 1059 consecutive patients who underwent preoperative carotid screening by magnetic resonance angiography, 84 (7.9%) patients had >50% stenosis; 45 of them underwent brain single-photon emission computed tomography. The severity of cerebral blood flow compromise was estimated by the proportion of Stage 2 area in the affected territory, in which both resting blood flow (<32 ml/min) and flow reserve (<10%) were reduced. RESULTS: Perioperative stroke occurred in 1.7% overall (18/1059), in 6% (5/84) of those with carotid stenosis and in 1.3% (13/975) of those without stenosis (P = 0.010). On subgroup analysis, carotid stenosis was associated with an increased risk of stroke in the on-pump surgery group [n = 949, 5/59 (9%) with stenosis vs 11/890 (1.1%) without stenosis, P = 0.002], while it was not in the off-pump group [n = 110, 0/25 (0%) with stenosis vs 2/85 (2%) without stenosis, P = 0.59]. With respect to the role of acetazolamide single-photon emission computed tomography, 2 of the 4 patients with Stage 2 area >10% undergoing on-pump surgery without preceding carotid revascularization developed stroke, while none of the 21 patients with Stage 2 area <10% undergoing on-pump surgery developed stroke (P = 0.020). CONCLUSIONS: Carotid stenosis is a risk factor for perioperative stroke in on-pump surgery. Patients with large Stage 2 area (>10%) are at increased risk of perioperative stroke when on-pump surgery is performed.

Secondary graft-oesophageal fistula after total arch replacement.

Secondary graft-oesophageal fistula is a fatal complication of aortic arch replacement. We report a successful two-stage surgical management of a graft-oesophageal fistula seen in a 68-year-old woman 3 years after total aortic arch replacement. She presented with a prolonged intractable fever without haematemesis. The fistula occurred between the distal aortic anastomosis and oesophagus; the entire graft was surrounded by air. In the first-stage operation, we performed re-replacement of the entire infected graft, oesophagectomy with cervical oesophagostomy, omental transfer and cervical routing of the stomach roll, through an extended left thoracotomy incision with sternal transection. Intravenous antibiotics were administered for 6 weeks; the second-stage cervico-oesophageal anastomosis was performed 57 days later. She was discharged without complications and is doing well 6 months postoperatively.

Spinal cord ischaemia after endovascular aneurysm repair.

We report the case of a patient who developed paraparesis 2 days after endovascular aneurysm repair for a right common iliac aneurysm. The patient had undergone thoracic endovascular aortic repair. The left subclavian artery was occluded, but the left internal iliac artery was preserved. The patient fully recovered from the paralysis within 3 months. This case illustrates the importance of collateral blood supply to the spinal cord from the lumbosacral region, especially when other sources are occluded.

Valve-sparing aortic root replacement for a prolapsing asymmetric valve.

Valve-sparing aortic root replacement remains challenging for patients with eccentric severe aortic regurgitation when the cusps are totally asymmetric. We report a case of successful reimplantation operation for such a lesion. Because free margin lengths from commissure to Arantius body of the adjacent two cusps were matched while inter-commissural distances were totally different, right coronary cusp prolapse was corrected by asymmetrically aligning the position and height of three commissures without cusp plication.

Characterizing saccular aortic arch aneurysms from the geometry-flow dynamics relationship.

OBJECTIVE: Low wall shear stress (WSS) has been reported to be associated with accelerated atherosclerosis, aneurysm growth, or rupture. We evaluated the geometry of aortic arch aneurysms and their relationship with WSS by using the 4-dimensional flow magnetic resonance imaging to better characterize the saccular aneurysms. METHODS: We analyzed the geometry in 100 patients using multiplanar reconstruction of computed tomography. We evaluated WSS and vortex flow using 4-dimensional flow magnetic resonance imaging in 16 of them, which were compared with 8 age-matched control subjects and eight healthy young volunteers. RESULTS: Eighty-two patients had a saccular aneurysm, and 18 had a fusiform aneurysm. External diameter/aneurysm length ratio and sac depth/neck width ratio of the fusiform aneurysms were constant at 0.76 ± 0.18 and 0.23 ± 0.09, whereas those of saccular aneurysms, especially those involving the outer curvature, were higher and more variable. Vortex flow was always present in the aneurysms, resulting in low WSS. When the sac depth/neck width ratio was less than 0.8, peak WSS correlated inversely with luminal diameter even in the saccular aneurysms. When this ratio exceeded 0.8, which was the case only with the saccular aneurysms, such correlation no longer existed and WSS was invariably low. CONCLUSIONS: Fusiform aneurysms elongate as they dilate, and WSS is lower as the diameter is larger. Saccular aneurysms dilate without proportionate elongation, and they, especially those occupying the inner curvature, have higher and variable sac depth/neck width ratio. When this ratio exceeds 0.8, WSS is low regardless of diameter, which may explain their malignant clinical behavior.