Experimental Evaluation of Sub-Sampling IQ Detection for Low-Level RF Control in Particle Accelerator Systems.

The low-level radio frequency (LLRF) control system is one of the fundamental parts of a particle accelerator, ensuring the stability of the electro-magnetic (EM) field inside the resonant cavities. It leverages on the precise measurement of the field by in-phase/quadrature (IQ) detection of an RF probe signal from the cavities, usually performed using analogue downconversion. This approach requires a local oscillator (LO) and is subject to hardware non-idealities like mixer nonlinearity and long-term temperature drifts. In this work, we experimentally evaluate IQ detection by direct sampling for the LLRF system of the Polish free electron laser (PolFEL) now under development at the National Centre for Nuclear Research (NCBJ) in Poland. We study the impact of the sampling scheme and of the clock phase noise for a 1.3-GHz input sub-sampled by a 400-MSa/s analogue-to-digital converter (ADC), estimating amplitude and phase stability below 0.01% and nearly 0.01°, respectively. The results are in line with state-of-the-art implementations, and demonstrate the feasibility of direct sampling for GHz-range LLRF systems.

Cardiac autotransplantation for malignant or complex primary left-heart tumors.

Malignant or complex benign tumors of the left heart can present a formidable challenge for complete resection, due to anatomic inaccessibility. Cardiac autotransplantation (cardiac explantation, ex-vivo tumor resection, reconstruction, and reimplantation) was introduced for complex benign primary left-heart cardiac tumors by Cooley and for malignant left-heart tumors by Reardon. Herein, we update our previously reported experience.From April 1998 through July 2008, 20 patients underwent 21 cardiac autotransplantations for complex left-sided cardiac tumors that were nonresectable by traditional means. Demographics, tumor histology, operative data, and mortality rates were analyzed. Follow-up was complete in all patients.Of the 20 patients, 17 had malignant lesions, and 3 had benign disease. Two patients had left ventricular lesions and the rest had left atrial lesions. Histology showed 7 malignant fibrous histiocytomas, 5 undifferentiated sarcomas, 3 leiomyosarcomas, 1 malignant osteosarcoma, 1 myxoid sarcoma, 2 paragangliomas, and 1 myxoma. Fourteen patients had previous resection of their cardiac tumors, and 1 patient had repeat autotransplantation for recurrent disease. There were no operative deaths in patients undergoing autotransplantation alone (0/15), and 3 operative deaths in patients undergoing combined cardiac autotransplantation and pneumonectomy (3/6, 50%). All 3 patients with benign disease survived surgery and are alive without recurrent disease. Local recurrence occurred in 3/18 patients with malignant disease: 1 underwent successful repeat autotransplantation and 2 are receiving chemotherapy. The mean survival for all patients with sarcoma is 22 months.Cardiac autotransplantation enables complete resection and accurate reconstruction in many primary malignant and complex benign left-heart tumors.

Cardiac autotransplantation for surgical resection of a primary malignant left ventricular tumor.

Primary cardiac sarcomas are rare. In such tumors, surgical resection is sometimes considered necessary to correct obstruction of flow caused by the tumor and to accomplish complete resection. The anatomic difficulties associated with large, primary, intracavitary left-sided sarcomas have led us to use cardiac explantation, ex vivo tumor resection, and cardiac autotransplantation to meet the anatomic challenges of left atrial tumors. We report the case of a patient who had a large, primary, intracavitary, left ventricular sarcoma that was successfully removed by cardiac explantation and ex vivo reconstruction with use of the cardiac autotransplantation technique. This is the 1st report describing the use of cardiac autotransplantation to surgically resect an intracavitary left ventricular malignancy.

Response to aspirin and clopidogrel in patients scheduled to undergo cardiovascular surgery.

BACKGROUND: Recent data indicate that among patients undergoing percutaneous coronary intervention low platelet response to aspirin is associated with clopidogrel low response. It is unclear whether these findings extend to other patient populations. We, therefore, aimed to evaluate the relation between response to aspirin and clopidogrel among patients scheduled to undergo cardiac or vascular surgery. METHODS: Patients who were scheduled for cardiac or vascular surgery and had taken aspirin 81-325 mg daily for at least a week and clopidogrel 75 mg daily for at least 3 days underwent blood testing for platelet function. One hundred patients were included in the current analysis. Platelet function was evaluated by the modified TEG platelet mapping assay with addition of ADP or arachidonic acid (AA), and by the PFA-100 assay with collagen-epinephrine (CEPI) or collagen-ADP (CADP) cartridges. Low response to aspirin or clopidogrel was defined as inhibition < or =20% for TEG-AA or TEG-ADP, respectively. RESULTS: Thirteen patients (13%) were low responders to aspirin and 34 (34%) were low responders to clopidogrel. Eight patients were low responders to both drugs. There were no differences in clinical characteristics between drug low responders versus sensitive patients. Aspirin low responders had lower TEG-ADP inhibition (19.5 +/- 6 vs. 35.8 +/- 3%, P = 0.03) and tended to have lower PFA-CADP time (84.7 +/- 7 vs. 105.6 +/- 5 s, P = 0.1) than aspirin sensitive patients. Clopidogrel low responders had lower TEG-AA inhibition (58 +/- 6 vs. 75.1 +/- 4%, P = 0.01) and PFA-CEPI time (168 +/- 13 vs. 200.4 +/- 10 s, P = 0.07) than clopidogrel sensitive patients. CONCLUSIONS: In patients scheduled to undergo cardiovascular surgery low response to aspirin is associated with low response to clopidogrel.

Cardiac autotransplantation for primary cardiac tumors.

BACKGROUND: Complete tumor resection is the optimal treatment of cardiac tumors. Anatomic accessibility and proximity to vital structures complicates resection of tumors involving the left heart. The results of standard resection and resection with orthotopic heart transplantation are dismal. We, therefore, reviewed our series of patients with complex left-sided primary cardiac tumors who underwent tumor resection with cardiac autotransplantation. METHODS: Since April 1998, 11 consecutive patients with complex left atrial or left ventricular intracavitary cardiac tumors underwent 12 resections using cardiac autotransplantation-cardiac explantation, ex vivo tumor resection with cardiac reconstruction, and cardiac reimplantation. Demographics, tumor histology, operative data, and mortality were analyzed. Follow-up was complete in all patients. RESULTS: Complete resection by cardiac autotransplantation was used in 7 patients with left atrial sarcoma, 1 patient with left ventricular sarcoma, 2 patients with left atrial paraganglioma, and 1 patient with a complex giant left atrial myxoma. Eight patients had previous resection of their cardiac tumor, and 1 patient had a repeat autotransplantation for recurrent disease. There were no operative deaths. Median overall survival was 18.5 months in patients with sarcomas. All patients with benign tumors are alive without evidence of recurrence. CONCLUSIONS: Cardiac autotransplantation is a feasible technique for resection of complex left-sided cardiac tumors. Recurrent disease after previous resections can be safely treated with this technique. Operative mortality and overall survival seems favorable in this series of patients. Benefits of this technique include improved accessibility and ability to perform a complete tumor resection with reliable cardiac reconstruction.