Masahiko Ezure

Open stent-grafting for aortic arch aneurysm is associated with increased risk of paraplegia

BACKGROUND Open surgery using the endovascular stent-graft is a novel technique that lessens the invasiveness of surgery for the aortic arch. However, the outcome of this procedure remains uncertain. METHODS Between November 1996 and July 2000, a total of 19 patients underwent open surgery using an endovascular stent-graft for thoracic aortic aneurysms. There were 15 men (78.9%) and 4 women (21.1%). Patient age ranged from 29 to 82 years (mean 69.3 years, median 74 years). Atherosclerotic thoracic aortic aneurysms were present in 17 patients (89.4%) and aortic dissection in 2 patients (10.5%). RESULTS Two patients (10.5%) died in the hospital and 4 patients (21.1%) presented with paraplegia postoperatively. Among the 4 patients with postoperative paraplegia, 1 case was complicated with intraoperative aortic dissection. The other 3 patients with paraplegia had spinal cord ischemic time of more than 60 minutes and intraoperative body weight gain of more than 4 kg. Of these 3 patients, hemodynamic instability after cardiopulmonary bypass was observed in 1 patient and cholesterin embolus in the anterior spinal artery was found at autopsy in another. On univariate analysis, age greater than 75 years was the only risk factor associated with paraplegia (p < 0.05). Autopsy findings for the 2 patients showed that the Adamkiewicz arteries were not blocked by the stent-graft in either patient. CONCLUSIONS Intraoperative aortic dissection, embolization of the intercostal arteries, long ischemic time of the spinal cord, and excessive weight gain during operation may have been associated with the high incidence of paraplegia after open surgery using the endovascular stent-graft.

Long-Term Results of Cryoablation with a New Cryoprobe to Eliminate Chronic Atrial Fibrillation Associated with Mitral Valve Disease

The purpose of this study was to examine the performance of a new cryoprobe in the treatment of chronic atrial fibrillation (AF) associated with mitral valve disease. The study included 66 patients undergoing mitral valve replacement. The mean AF duration was 9.0 ± 9.0 years and mean left atrial (LA) was diameter 57 ± 10 mm. Cryoablation (−60°C) was applied to four pulmonary vein (PV) orifices over 2–3 minute. The spherical tip (2‐cm in diameter) of the cryoprobe is capable of ablating the left atrium near the PV, as well as the PV ostium with a single cryoablation. After cryoablation, mitral valve surgery or a combined surgical procedure were performed in 66 patients. There were no intraoperative complications. Sinus rhythm was restored in 60 patients (91%) immediately after the operation. Recurrent AF was treated with antiarrhythmic drugs and/or direct current cardioversion in 43 patients (72%). At discharge, 48 patients (72%) were in sinus rhythm. During a mean follow‐up period of 31 ± 16 months, 40 patients (61%) were in sinus rhythm with (29) or without antiarrhythmic drugs (11). In patients in sinus rhythm at the end of the follow‐up period, the duration of preoperative AF duration was significantly shorter (P < 0.05) and the preoperative LA diameter and cardiothoracic ratio were significantly smaller than in patients who were in AF (both for P < 0.005). Using this new cryoprobe, sinus rhythm was restored and maintained in 61% of patients with chronic AF and mitral valve disease with a 12–15 minute cryoablation procedure.

Minimal damage during endoscopic latissimus dorsi muscle mobilization with the harmonic scalpel

BACKGROUND To reduce wound-related complications, a video-assisted surgical technique has been adopted for the mobilization of the latissimus dorsi muscle. We postulated that thermal damage to the muscle might be minimized by using a Harmonic Scalpel instead of electrocautery during this procedure. METHODS Canine latissimus dorsi muscles were mobilized through a small incision, assisted by a videoscope. In 6 dogs, dissection with electrocautery was used to mobilize the latissimus dorsi muscle. In 6 other dogs, the Harmonic Scalpel was used. We compared operation times, wound infection rates, histologic changes in the muscles, and ease of handling between these groups. RESULTS The operation time was significantly shorter in the Harmonic Scalpel group than in the electrocautery group (61.5 versus 106.5 minutes, p = 0.00014). The Harmonic Scalpel caused less histologic damage to the mobilized muscles and produced less vision-obscuring smoke. CONCLUSIONS The Harmonic Scalpel shortens the operation, minimizes muscle damage, and facilitates the performance of video-assisted latissimus dorsi muscle mobilization.

Postoperative Hyperglycemia and Atrial Fibrillation After Coronary Artery Bypass Graft Surgery

BACKGROUND Postoperative atrial fibrillation (AF) is a common complication following coronary artery bypass grafting (CABG). We investigated the risk factors for postoperative AF and analyzed the relationship between blood sugar concentration (BS) and AF after CABG. METHODS AND RESULTS A total of 199 consecutive patients who underwent isolated CABG were retrospectively examined and classified according to the presence (n=95) or absence (n=104) of postoperative AF. On univariate analysis mean postoperative BS (P<0.001), postoperative drainage volume (P<0.001), age (P=0.034), presence of diabetes mellitus (DM; P=0.004), and postoperative estimated glomerular filtration rate (P=0.032) were significant risk factors for postoperative AF. On multivariate analysis mean postoperative BS (OR, 1.041; 95% CI: 1.008-1.079; P<0.001), postoperative drainage volume (OR, 1.003; 95% CI: 1.001-1.006; P=0.001), and age (OR, 1.040; 95% CI: 1.002-1.083; P=0.041) were significant risk factors for postoperative AF. Postoperative AF often occurred in patients with high postoperative BS, irrespective of DM. The BS cut-off that predicted postoperative AF occurrence was 180 mg/dl. A strong positive correlation existed between the time of the maximum postoperative BS and AF onset time (ρ=0.746). CONCLUSIONS Mean postoperative BS and postoperative drainage volume are risk factors for AF after CABG. AF was strongly associated with maximum postoperative BS. Intensive glycemic control could reduce AF occurrence after CABG.

Metastatic hepatocellular carcinoma obstructing the right ventricular outflow tract

A 49-year-old female with a past history of liver resection due to hepatocellular carcinoma was referred to our Department for treatment of a metastatic cardiac tumor obstructing the right ventricular outflow tract. She underwent operation twice with cardiopulmonary bypass, and symptoms were relieved. Metastasis from hepatocellular carcinoma to the heart is very rare, but should be taken into consideration during follow-up after treatment for a primary liver tumor.

Thoracoscopic Cardiomyoplasty: a Canine Feasibility Study

BACKGROUND Thoracoscopy may be effective in reducing the surgical stress of cardiomyoplasty. The feasibility of thoracoscopy in cardiomyoplasty was investigated. METHODS Cardiomyoplasty by thoracoscopy and by the open method through a thoracotomy was performed in dogs. After 8 to 10 weeks of preconditioning, the hemodynamic effect of burst stimulation was measured. RESULTS Cardiomyoplasty by thoracoscopy took 90 +/- 21 minutes (mean +/- standard deviation), whereas cardiomyoplasty by the open method took 67 +/- 10 minutes (p < 0.05). As a result of burst stimulation, aortic pressure, descending aortic flow, and left atrial pressure increased by 15.1% +/- 6.5%, 8.6% +/- 6.3%, and 3.8% +/- 4.6%, respectively, in the dogs that received the cardiomyoplasty by thoracoscopy, whereas those indices increased by 16.5% +/- 6.9%, 9.8% +/- 5.9%, and 4.8% +/- 4.2%, respectively, in dogs that received cardiomyoplasty by the open method. No significant difference between the two groups was shown in any index. CONCLUSIONS Cardiomyoplasty by thoracoscopy was technically practical, and its hemodynamic effect was similar to that of the open method. The feasibility of cardiomyoplasty by thoracoscopy was thereby suggested.

Ultrathin-wall vascular grafts for endovascular surgery

Abstract The purposes of this study were to develop ultrathin-wall grafts suitable for stent-graft procedures and to examine the feasibility of the grafts from the physical point of view. We fabricated ultrathin-wall grafts with a wall thickness of 42 to 137 μm, using 50 denier polyester threads consisting of 72 polyester monofilaments. We studied the following physical properties of the ultrathin wall: the surface structure of the grafts, the longitudinal tensile strength of the grafts, the water permeability of the grafts, and the size of introducers through which the stent grafts can pass. In ultrathin-wall grafts with a wall thickness of 75 μm or more, a regular surface structure with zero planimetric porosity was recognized. In those with a thickness less than 64 μm, the porosity increased as the wall thickness decreased. The longitudinal tensile strengths of the 75 μm and 64 μm grafts were 13.1 ± 0.9 and 9.5 ± 0.9 kg, respectively. The water permeability of the 75-μm grafts was 380 ml/min, and that of the thinner grafts increased as the wall thickness decreased. Stents with a diameter of 40 mm covered with the ultrathin-wall grafts could pass through introducers with an inner diameter of 18 French. We conclude that the newly developed ultrathin-wall grafts are physiologically suitable for endovascular surgery.

Repair of Ruptured Anastomotic Aneurysm: Elephant Trunk Technique After Endovascular Covered Stents

Endovascular covered stents were successfully applied to temporarily halt hemoptysis and postpone surgical intervention in a 69-year-old man with a ruptured anastomotic false aneurysm of the distal aortic arch. Surgical graft implantation was performed successfully by the elephant trunk technique 14 days after the endovascular stent-grafting, at which time aspiration pneumonia had subsided.

Starr–Edwards caged‐ball aortic valve: preserved function 40 years after implantation

A 77-year-old male was admitted with exertional dyspnea (New York Heart Association [NYHA] class III) following an aortic valve replacement with a #27 Starr–Edwards prosthesis (model no. 2400; Edwards Lifesciences, Inc., Irvine, CA, USA) in 1976 at age 37. He had no bleeding or thromboembolic events and the valve appeared to be functioning well on fluoroscopy (Figure 1). Transthoracic echocardiography showed a well-seated prosthesis with trivial central aortic insufficiency (AI), no paravalvular leaks, and an ejection fraction of 65%. However, the peak velocity was 3.3 m/sec, the peak gradient was 56mmHg, and the mean gradient was 28mmHg, resulting in an effective orifice area index of 0.74 cm/m consistent with prosthesis-patient mismatch. The patient underwent an uncomplicated reoperative aortic valve replacement with a #21 Carpentier–Edwards Perimount Magna Ease bioprosthesis (Edwards Lifesciences, Inc.). The explanted Starr–Edwards valve showed no thrombus formation or structural abnormalities (Figure 2). At two months follow-up, the patient was in NYHA Class I and a transthoracic echocardiogram showed no AI, a peak jet velocity of 2.4m/sec, a mean gradient of 12mmHg, and an effective orifice area index of 1.05 cm/m.

Circulatory Assistance Using Linear Skeletal Muscle Ventricle

We have developed a novel type of skeletal muscle ventricle (linear skeletal muscle ventricle: LSMV). The LSMV is powered by linear contraction of the latissimus dorsi muscle which is stretched by regurgitation of the highly pressurized aortic blood into the LSMV during muscle relaxation. The LSMV consists of two cylindrical bellows of different diameters joined by a connector containing a valve. The smaller bellows is connected to the left atrium with another valve, and the larger bellows is connected to the aorta. The latissimus dorsi muscle is attached to the connector so that its contraction pulls the connector to compress the larger bellows and to stretch the smaller bellows.