Sutureless replacement of aortic valves with St Jude Medical mechanical valve prostheses and Nitinol attachment rings: feasibility in long-term (90-day) pig experiments

Objective: Nitinol attachment rings (devices) used to attach mechanical aortic valve prostheses suturelessly were studied in long-term (90 days) pig experiments. Methods: The aortic valve was removed and replaced by a device around a St Jude Medical mechanical valve prosthesis in 10 surviving pigs. Supravalvular angiography was done at the end of the operation. No coumarin derivates were given. Results: No or minimal aortic regurgitation was confirmed in all surviving pigs at the end of the operation. Total follow-up was 846 days. In 4 pigs, follow-up was shorter than 90 days (28-75 days); the other 6 pigs did reach 90 days' survival or more. Repeat angiography in 4 pigs at the end of follow-up confirmed the unchanged position of the device at the aortic annulus, without aortic regurgitation. At autopsy, in all pigs the devices proved to be well grown in at the annulus, covered with endothelium, and sometimes tissue overgrowth related to not using coumarin derivates. There was no case of para-device leakage, migration, or embolization. No damage to surrounding anatomic structures or prosthetic valves was found. Conclusions: Nitinol attachment rings can be used to replace the aortic valve suturelessly with St Jude Medical mechanical aortic valve prostheses, without para-device leakage, migration, or damage to the surrounding tissues, in long-term pig experiments during a follow-up of 90 days or more. Refraining from anticoagulation in pigs with mechanical valve prostheses can lead to tissue overgrowth of the valve prosthesis. Further studies are needed to determine long-term feasibility of this method in human beings

Noninvasive assessment of right gastroepiploic artery graft patency using transcutaneous color Doppler echocardiography

\u3cp\u3eBackground. Because the right gastroepiploic artery graft (GEA), when routed antegastrically, is situated just behind the abdominal wall, we investigated the possibility of evaluating graft patency and flow characteristics using transabdominal color Doppler echocardiography. Methods. The right GEA graft was evaluated in 71 patients who underwent complete arterial revascularization, 4 months (range, 2 to 17 months) postoperatively. Selective angiography of the right GEA was performed in the patients in whom the graft could not be visualized using color Doppler echocardiography. Results. Flow in the right GEA graft was detected in 65 (91.5%) of 71 patients using color Doppler echocardiography. In all visualized right GEAs, a biphasic flow pattern was observed, with higher peak velocity during systole. Mean (± standard deviation) peak systolic velocity was 76 ± 16 cm/s. Mean (± standard deviation) velocity was 41 ± 14 cm/s. Selective angiography of the right GEA in 5 patients in whom the graft could not be visualized using echocardiography showed four patent and functional grafts and one graft that was open but not functional ('slender sign'). One patient died before angiography could be performed. The sensitivity of noninvasive ultrasound assessment of the patency of the right GEA graft was 94% (65 of 69 patients). In this group of patients, an overall right GEA graft patency rate of 97% (69 of 71 patients) was found at mean follow-up of 4 months (range, 2 to 17 months). Conclusions. The right GEA graft is an adequate coronary artery graft with a good short-term patency rate, and transcutaneous color Doppler echocardiography is a useful tool for evaluating its patency and flow characteristics. Selective angiography of the right GEA can be avoided in most cases and is indicated only when the graft cannot be detected using Doppler echocardiography.\u3c/p\u3

Noninvasive assessment of coronary flow reserve in the right gastroepiploic artery graft

Background. To investigate the functional capacity of the right gastroepiploic artery graft (GEA) and its ability to adapt to provide adequate flow at peak myocardial demand, we investigated the feasibility of determining coronary flow reserve (CFR) provided by this vessel using transabdominal color Doppler echocardiography and the correlation between this noninvasive determination of flow reserve and nuclear stress scintigraphy. Methods. In 40 selected patients, who underwent complete arterial myocardial revascularization using the GEA and the internal thoracic arteries (ITAs), CFR of the GEA was measured at maximum coronary hyperemia induced by intravenous adenosine infusion, 7 months (range 3 to 20) after surgery. In the same period, in 31 of this group of patients, exercise thallium scintigraphy was performed. Results. We succeeded in measuring CFR in 37 of 40 patients with values ranging from 1.1 to 3.6 with an average of 2.1 ± 0.7. During adenosine infusion, mean velocity in the GEA significantly increased from 48 ± 20 to 89 ± 41 cm/sec (p ≤ 0.001), mean arterial blood pressure significantly decreased from 96 ± 11 to 87 ± 11 mm Hg (p ≤ 0.001), and heart rate significantly increased from 74 ± 11 to 87 ± 15 beats/min (p ≤ 0.001). In 8 of these 37 patients, the nuclear exercise test was positive (compatible with reversible ischemia in the distribution area of the GEA). Average CFR in these 8 patients with positive nuclear stress test was 1.46 ± 0.28 versus 2.27 ± 0.70 in those patients with a negative test (p ≤ 0.001). Conclusions. Noninvasive determination of CFR of GEAs is feasible, using transabdominal Doppler echocardiography. The present study shows that coronary vasodilator reserve and autoregulation is maintained in myocardium supplied by the GEA and that the CFR has a significant correlation with the results of noninvasive nuclear exercise testing. Therefore, noninvasive determination of CFR by transabdominal Doppler echocardiography might be a valuable contribution to functional assessment of GEAs

Venovenous Long Term Extracorporeal CO

A 14-year-old male patient developed a severe respiratory insufficiency after a cart racing accident complicated by a bilateral pneumothorax, lung contusion and a rupture of a segmental lobe bronchus, for which two subsequential surgical interventions were needed. Due to a decreased lung compliance, alveolar ventilation was decreased to a minimum, resulting in the development of hypercapnia. The patient was placed on partial venovenous bypass utilizing the Biomedicus centrifugal pump and two Sarns hollow fiber membrane oxygenators, in combination with low frequency positive pressure ventilation, for extracorporeal CO2 removal with limited anticoagulation. This case report illustrates the safe use and continuous effective performance of the hollow fiber membrane oxygenator and centrifugal pump for more than 60 hours. Despite all efforts to create an environment for the lungs to heal, the patient succumbed due to irreversible traumatic cerebral damage and the bypass procedure was terminated after 60 hours

The Impact of New-Onset Postoperative Atrial Fibrillation on Mortality After Coronary Artery Bypass Grafting

Background. New-onset postoperative atrial fibrillation (POAF) is a frequent rhythm disturbance after coronary artery bypass grafting (CABG). This study investigated the independent effect of POAF on early and late mortality after isolated CABG. Methods. Data of patients who consecutively underwent isolated CABG between January 2003 and December 2007 were prospectively collected. The analysis included 5098 patients with preoperative sinus rhythm and no history of atrial fibrillation. Logistic regression analysis for early mortality and Cox regression analysis for late mortality were performed. Propensity score matching was performed to eliminate the effect of confounders. Results. Median follow-up was 2.5 years. POAF was documented in 1122 patients (22.0%). Early mortality was more frequent in POAF patients (3.1%) vs non-POAF patients (1.6%, p = 0.002), but multivariate logistic regression analysis could not identify POAF as an independent predictor of early mortality (p = 0.169). This outcome did not change after adjusting for quintiles of the propensity score of POAF (p = 0.100). Multivariate Cox proportional hazard analyses demonstrated POAF was an independent predictor of overall and late mortality with hazard ratios of 1.35 (p = 0.012 and p = 0.039, respectively). Analyses after propensity score matching showed that patients with POAF had similar hazard ratios of 1.36 for overall mortality and 1.34 for late mortality (p = 0.009 and p = 0.042, respectively). Conclusions. POAF is an independent predictor of overall and late mortality after isolated CABG but not of early mortality

Fast sutureless implantation of mechanical aortic valve prostheses using Nitinol attachment rings: feasibility in acute pig experiments

Objective: There is a need for fast sutureless implantation of valve prostheses with a better outcome than that of current valved stents. Methods: The suture ring of a St Jude mechanical valve prosthesis (St Jude Medical, Minneapolis, Minn) was replaced by a proprietary non-stent-based attachment ring C made of Nitinol memory metal (Endosmart, Stutensee, Germany) and covered with textile. In acute pig experiments, the aortic valve was removed and the device was introduced in a temporary stretched shape and activated by removing constrainers and heating to reach its final attachment shape. Results: The devices could be actuated within seconds. Echocardiography showed normal prosthetic valve and heart function. No paradevice leakage was demonstrated by supravalvular angiography. At autopsy, no abnormalities were found in the surrounding structures or valve prostheses. Pulling tests showed the strong adhesive power of Nitinol attachment rings withstanding up to 5 kg of pulling force. Conclusion: Nitinol memory metal attachment rings, covered with textile, around suture ring-denuded St Jude mechanical aortic valve prostheses enabled fast and strong sutureless implantation in acute pig experiments. Further studies in chronic animal models and humans are needed to determine long-term safety