A study of implanted cardiac rhythm recorders in advanced cardiac AL amyloidosis

AIMS

AL amyloidosis may respond to chemotherapy but two-thirds of patients with severe cardiac involvement die within a year of diagnosis, purportedly from tachyarrhythmias or electromechanical dissociation. We sought to characterize the nature of cardiac arrhythmias in severe cardiac AL amyloidosis using implanted cardiac rhythm recorders.

METHODS AND RESULTS

Implantable loop recorders (ILRs) were inserted within 24 h of baseline evaluation at the UK National Amyloidosis Centre, into 20 consecutive patients with newly diagnosed severe cardiac AL amyloidosis and symptoms of syncope or pre-syncope. Weekly ILR recordings and additional recordings at the time of symptoms were obtained. Median (range) follow-up from baseline was 308 (10-399) days. Thirteen patients died, and median survival in the whole cohort was 61 days from device insertion. In each of eight evaluable cases, death was heralded by bradycardia, usually associated with complete atrioventricular block (CAVB), followed shortly thereafter by pulseless electrical activity. Four patients received pacemakers, a median (range) of 7 (3-38) h after development of symptomatic CAVB, but these did not prevent rapid cardiac decompensation and death in three cases. Despite 272 loop recordings, there was only one episode of non-sustained ventricular tachycardia, which was preceded by severe bradycardia. Patients who died had significantly worse global left ventricular strain on echocardiography (P = 0.029) and reduced 6 min walk distance (P = 0.048) at baseline compared with survivors.

CONCLUSIONS

The discovery that bradyarrhythmias heralded terminal cardiac decompensation in most patients with severe cardiac AL amyloidosis supports a study of prophylactic pacemaker insertion in this patient population.

Evaluation of the Maquet Neonatal and Pediatric Quadrox I with an integrated arterial line filter during cardiopulmonary bypass

BACKGROUND

Perfusion equipment has evolved since its introduction into clinical practice more than fifty years ago to include smaller cardiopulmonary bypass (CPB) circuits and components. Perfusionists are now exploring the function of new oxygenators with an integrated arterial line filter (IALF). The purpose of this trial was to examine the Maquet Quadrox-I Neonatal and Pediatric oxygenators with IALF in a clinical setting, with respect to gas transfer, heat exchange co-efficiency (HEC), trans-membrane pressure (TMP) gradient and clinical experience.

METHODS

The Maquet Quadrox-I Neonatal oxygenator was used on 30 patients ranging from 2.2-13.1 kg. The Maquet Quadrox-I Pediatric oxygenator was used on 15 patients ranging from 12.7-24.5 kg. Arterial and venous blood gases were taken once the patient was stable on CPB and, subsequently, every 30 minutes afterwards, as per institution protocol. The values for gas transfer rates, HEC and TMP gradient were stratified into three main categories with each oxygenator: normothermia, cooling and re-warming.

RESULTS

During all conditions, the gas transfer rate with both oxygenators was efficient. The HEC values showed efficient heat exchanger performance during all conditions with both oxygenators. While maintaining CPB flow within the manufacturer's recommended flow rate for each oxygenator, the TMP gradient range for the Neonatal Quadrox-I was 10-40 mmHg and the Pediatric Quadrox-I was 10-60 mmHg. During the clinical trial, foam was shown to break through the cardiotomy on several occasions when high sucker return was required.

CONCLUSION

This new line of oxygenators performed well with regards to gas transfer, HEC and TMP gradient, but there were clinical experiences that did not meet expectations. There were repeated incidences with the venous reservoir which ultimately cast a negative light on the design of this new product from Maquet. In the future, the authors would like to evaluate updated versions of this product from Maquet and any other pediatric perfusion devices that could help the patient in the clinical arena.

SU-E-T-482: A More Accurate Bare 12 5I Spectrum

PURPOSE

To compare measured energy spectra of ¹²⁵ I brachytherapy seeds with Monte Carlo calculated energy spectra when using the bare ¹²⁵ I energy spectrum recommended by TG43 and the one presented in NCRP Report 58 and to determine the impact of these different spectra on the calculation of the dose rate constant.

METHODS

The energy spectrum, absorbed dose at 1 cm on the bisector and air kerma strength of 10 different ¹²⁵ I seeds were calculated using the EGSnrc BrachyDose Monte Carlo code. Energy bin width was 0.2 keV. The simulations were done with the bare ¹²⁵ I energy spectrum recommended by TG43 or NCRP Report 58. Statistical uncertainties for the energy spectra were 0.02% and 0.1% or less for the other clinical parameters. Results are compared with published measuredvalues.

RESULTS

There is close agreement between the measured and calculated branching ratio generated by ¹²⁵ I seeds when simulated using the spectrum presented in NCRP58. However, for all seeds a 7% lower value is observed in the 31 keV peak when using data suggested by TG43. On the other hand, differences in the average energy, air kerma, absorbed dose and dose rate constant are undetectable (less than statistical uncertainty, <0.1%) when performed with either spectrum.

CONCLUSIONS

For dosimetric parameter calculations, the bare ¹²⁵ I energy spectra presented in TG43 and NCRP58 produce indistinguishable results. However, for branching ratio investigation purposes, there is a clear difference in the 31 keV peak between values obtained using the different ¹²⁵ I bare energy spectra. Measured ¹²⁵ I branching ratios are in close agreement with those calculated using the bare ¹²⁵ I energy spectrum presented in NCRP58. Reassessment of the bare ¹²⁵ I energy spectrum recommended in TG43 is suggested.

A systematic evaluation of the core communication skills expected of a perfusionist

Background: The objective of this systematic evaluation was to identify the sentinel standards necessary to obtain a core level of communication required of a clinical perfusionist during cardiopulmonary bypass (CPB). Once these sentinel standards were identified and a core level of communication was established (via four simulated case scenarios), a team of cardiac healthcare professionals was assembled to interpret both the accuracy of response and the speed of response encountered in each case scenario.

Methods: Four simulated case scenarios were utilized in order to replicate the typical patterns of verbal exchange that occur during surgeries using extracorporeal technology. The simulated case scenarios included CPB interactions associated with preparation, initiation, maintenance, termination and post CPB. For all CPB interactions, two variables were measured: accuracy of the perfusionist’s response and speed of the perfusionist’s response. The cases took place in a controlled setting within an empty operating room at The Children’s Hospital of Philadelphia. Four clinical perfusionists each represented the role of the “perfusionist” in all simulated case scenarios.

Results: When analyzing the accuracy and speed of the responses, each clinical perfusionist recorded an average score of 96.3% or higher with all case scenarios. Since the clinical perfusionists who participated in the scenarios were primarily pediatric perfusionists, the scores were best during the pediatric case scenario, 99.3% (Case Scenario #4). The lowest scores were captured during Case Scenario #3 (96.3%) which involved a more intense adult patient scenario.

Conclusion: The systematic evaluation of both response accuracy and response time (presented in various adult and pediatric patient case scenarios) can be beneficial within the realm of perfusion education. Students will be introduced to core communication concepts within the clinical realm. This study supports the idea that simulation and evaluation may ease the transition for students from the didactic to clinical realm in terms of communication. Further studies need to be developed in order to define “standard” CPB communication guidelines for perfusion students.

Multi-format all-optical processing based on a large-scale, hybridly integrated photonic circuit

We investigate through numerical studies and experiments the performance of a large scale, silica-on-silicon photonic integrated circuit for multi-format regeneration and wavelength-conversion. The circuit encompasses a monolithically integrated array of four SOAs inside two parallel Mach-Zehnder structures, four delay interferometers and a large number of silica waveguides and couplers. Exploiting phase-incoherent techniques, the circuit is capable of processing OOK signals at variable bit rates, DPSK signals at 22 or 44 Gb/s and DQPSK signals at 44 Gbaud. Simulation studies reveal the wavelength-conversion potential of the circuit with enhanced regenerative capabilities for OOK and DPSK modulation formats and acceptable quality degradation for DQPSK format. Regeneration of 22 Gb/s OOK signals with amplified spontaneous emission (ASE) noise and DPSK data signals degraded with amplitude, phase and ASE noise is experimentally validated demonstrating a power penalty improvement up to 1.5 dB.

Characterization of a ceramic ultrafiltration membrane in different operational states after its use in a heavy-metal ion removal process

In the present study, the atomic force microscopy (AFM) technique has been used to characterize a Carbosep M5 ceramic membrane (MWCO=10kDa, TiO(2)-ZrO(2) active layer). This membrane was previously used in a polymer supported ultrafiltration (PSU) process to recover copper, using partially ethoxylated polyethylenimine as the water-soluble polymer. The membrane was characterized in four different operational states: new, new and cleaned, fouled in a PSU stage and cleaned after a PSU process. The influence of the membrane state on pore opening size distribution and roughness was studied, finding a 16% decrease in the former and a 20% increase in the latter due to foulant deposition upon the membrane active layer. Phase angle distribution was also analyzed to indicate the foulant spreading on the membrane surface. These phase angle measurements can be related to pore opening size and roughness, concluding that the cleaning procedure is not totally effective and that foulant presence on the membrane active layer is not remarkable. Finally, AFM was used to measure the influence of pH on adhesion forces between a silica probe and the membrane active layer. These results can be related to the flux evolution vs pH in PSU experiments, finding both lowest adhesion and highest flux at pH 6.