On site cardiac surgery for structural heart interventions: a fence to mend?

Current evidence supports device-based transcatheter interventions for the management of patients with structural heart disease, proving well their safety and efficacy; transcatheter aortic valve implantation (TAVI), transcatheter edge-to-edge repair (TEER) of mitral or tricuspid valves, and left atrial appendage occlusion (LAAO) are expanding their role in contemporary practice. Currently, guidelines recommend performing TAVI in ‘Heart Valve Center’ with interventional cardiology and institutional on-site cardiac surgery (iOSCS), while no site limitation has been defined for TEER and LAAO. The growing number of candidates for transcatheter interventions generates long waiting times with negative consequences on mortality, morbidity, hospitalization, and functional deterioration. Therefore, a debate on the feasibility of TAVI in centres without iOSCS has been set up. Data from randomized controlled trials and registries failed to document any difference in outcomes and in conversion rate to emergent surgical bailout in centres with or without iOSCS; on the other hand, a direct relationship with TAVI complications has been clearly documented for learning curve and centre volume. Therefore, the role of iOSCS for TAVI, as well as for other transcatheter interventions, should be carefully explored.

In-vitro investigation of cardiac implantable electronic device malfunction during and after direct photon exposure: A three-centres experience

PURPOSE

Radiotherapy may cause malfunction of implantable cardioverter-defibrillators (ICDs) and pacemakers (PMs). We carried-out a multicentre randomized in-vitro study on 65 ICDs and 145 PMs to evaluate malfunctions during and after direct irradiation to doses up to 10 Gy.

METHODS

Three centres equipped with different linear accelerator and treatment-planning systems participated in the study. Computed Tomography (CT) acquisitions were performed to build the treatment plans. All devices were exposed to dose of 2, 5, or 10 Gy (6 MV). All devices underwent a baseline examination and 64 wireless real-time telemetry-transmissions (47 ICDs and 17 PMs) were monitored during photon exposures. All devices were interrogated after exposure and once monthly for six subsequent months.

RESULTS

Fifty-four of the 64 wireless-enabled CIEDs (84.4%) recorded noise-related interferences during exposure. In detail, 40/47 ICDs (85.1%) reported interference, of which 16 ICDs (34%) reported potentially clinically relevant pacing inhibition and inappropriate detections. Following exposure, a soft reset occurred in 1/145 PM (0.7%) while 7/145 PMs (4.8%) reported battery issues. During the six-month follow-up, 1/145 PM (0.7%) reported a soft reset, while 12/145 more PMs (8.3%) and 1/64 ICD (1.5%) showed abnormal battery depletion. All reported issues occurred independently of exposure dose. Finally, irreversible effects on software and battery life occurred in only non-MRI-compatible devices.

CONCLUSION

ICDs mostly featured real-time transient sensing issues, while PMs mostly experienced long-term battery or software issues that were observed immediately following radiation exposure and during follow-up. Irreversible effects on battery life and software occurred in only non-MRI-compatible devices.

The ‘dreaded PFO’: anatomical and functional features of high risk for stroke

Patent foramen ovale (PFO) has a high prevalence in general population and can be implicated in cryptogenic stroke among young people. Recent trials have shown that transcatheter PFO closure is superior to medical treatment in the secondary prevention of ischaemic stroke. The benefit in the reduction of stroke recurrence is particularly evident in patients who have documentation of a PFO with high-risk characteristics. Therefore, after the assessment of a clear causal relationship with the event, a thoughtful documentation of anatomic (height, length, presence of an aneurysmatic or a floppy atrial septum, a prominent Eustachian valve or Chiari’s network, an acute angle with the inferior vena cava) and functional high-risk characteristics is mandatory.

Is Occult Genetic Substrate the Missing Link Between Arrhythmic Mitral Annular Disjunction Syndrome and Sudden Cardiac Death?

We present the case of a 28-year-old man with a history of unexplained syncope, frequent ventricular arrhythmias, familial LMNA-related dilated cardiomyopathy (DCM) and mitral annular disjunction (MAD). We provide the first association of a novel truncating LMNA variant serving as a potential vulnerable substrate for arrhythmogenic MAD syndrome. This could suggest a possible synergistic role between concealed genetic variants (resulting in fibrosis as a 'substrate' for arrhythmogenesis) and the presence of mitral annular disjunction (the 'trigger' with mechanical stretch initiating ventricular arrhythmias), which may provide a link between mitral valve prolapse and sudden cardiac death.

Selection of the Optimal Candidate to MitraClip for Secondary Mitral Regurgitation: Beyond Mitral Valve Morphology

Secondary mitral regurgitation (MR) occurs despite structurally normal valve apparatus due to an underlying disease of the myocardium leading to disruption of the balance between tethering and closing forces with ensuing failure of leaflet coaptation. In patients with heart failure (HF) and left ventricular dysfunction, secondary MR is independently associated with poor outcome, yet prognostic benefits related to the correction of MR have remained elusive. Surgery is not recommended for the correction of secondary MR outside coronary artery bypass grafting. Percutaneous mitral valve repair (PMVR) with MitraClip implantation has recently evolved as a new transcatheter treatment option of inoperable or high-risk patients with severe MR, with promising results supporting the extension of guideline recommendations. MitraClip is highly effective in reducing secondary MR in HF patients. However, the derived clinical benefit is still controversial as two randomized trials directly comparing PMVR vs. optimal medical therapy in severe secondary MR yielded virtually opposite conclusions. We reviewed current evidence to identify predictors of PMVR-related outcomes in secondary MR useful to improve the timing and the selection of patients who would derive maximal benefit from MitraClip intervention. Beyond mitral valve anatomy, optimal candidate selection should rely on a comprehensive diagnostic workup and a fine-tuned risk stratification process aimed at (i) recognizing the substantial heterogeneity of secondary MR and its complex interaction with the myocardium, (ii) foreseeing hemodynamic consequences of PMVR, (iii) anticipating futility and (iv) improving symptoms, quality of life and overall survival.

Transient ICD malfunctions during oncologic radiotherapy: a multi-centre, randomized, in-vitro study

Background

Direct exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered potentially harmful, or even unsafe, by manufacturers and current recommendations. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and malfunctions may present during exposure.

Purpose

To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy RT, forty-three contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (ERI) were evaluated in a real-time in-vitro session in three different centres.

Methods

All ICDs had baseline interrogation. Single chamber devices were programmed to the VVI/40 mode and dual or triple chamber devices were programmed to the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still active. A centring computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2-, 5- or 10-Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy, the ICDs were observed in a real-time session using manufacturer specific programmer, and device function (pacing, sensing, programmed parameters, arrhythmia detections) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure.

Results

During radiotherapy course, almost all ICDs (93%) recorded major or minor transient electromagnetic interferences. On detail, sixteen ICDs (37.2%) reported atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. Twenty-four ICDs (55.8%) recorded non clinically relevant noise, and no detections were observed. Only three ICDs (7%) reported neither transient malfunction nor minor noise, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. Malfunctions occurred regardless of either 2-, 5- or 10-Gy photon beam exposure.

Conclusions

Transient electromagnetic interferences were observed in most of the contemporary ICDs during radiotherapy course, regardless of photon dose. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or ICD reprogramming to the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

Funding Acknowledgement

Type of funding source: None

Permanent CIED malfunctions after oncologic radiotherapy: a multi-centre, randomized, in vitro evaluation

Background

Direct photon exposure of pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs) during oncologic radiotherapy may transiently or permanently affect normal device function. To evaluate potential malfunctions by direct exposure to doses up to 10 Gy in 6-MV oncologic radiotherapy, commonly considered unsafe or even not recommended, 145 PMs and 65 ICDs were observed in three different centres.

Methods

All devices had a baseline interrogation and reprogramming to VVI/40 or to DDD/40 mode, depending on type and model. Rate-adaptive function was disabled in all the devices, whereas in ICDs, even antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation (VT/VF) windows left enabled. To build the corresponding treatment plan, a centring computed tomography was performed with different Treatment Plan Systems among the centres. The devices were blinded randomized to receive either 2-, 5- or 10-Gy direct exposure by a 6-MV linear accelerator (different among the three centres) in a water phantom (600 MU/min). The effective dose received was assessed by a random in-vivo dosimetry. All devices had a telemetry interrogation immediately after exposure and once monthly during a six-month follow-up.

Results

Immediately after photon exposure, no changes in device parameters or software errors were observed in 209 devices (99.5%). A non-reprogrammable reset to emergency back-up mode (VVI/65) occurred in a PM (0.5% overall; 0.7% among PMs). Seven PMs reached the Elective Replacement Indicator immediately after exposure (3.3% overall; 4.8% among PMs). Sixteen ICDs (7.6% overall; 24.6% among ICDs) had multiple VT/VF detections stored in the device memory. Two PMs (1% overall; 1.4% among PMs) reported atrial fibrillation detections.

During a six-month follow-up, a non-reprogrammable software reset (back-up to VVI/65 mode) was reported in one PM three months after a single exposure of 2 Gy (0.5% overall; 0.7% among PMs). Abnormal battery drain was observed in thirteen PMs (6.2% overall; 9% among PMs), and in one ICD (0.5% overall; 1.5% among ICDs). All events presented regardless of exposure dose of either 2, 5, or 10 Gy.

Conclusions

Last-generation devices, both PMs and ICDs, withstood direct 6-MV photon exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturer statements and clinical guidelines. The most common failures were referred to battery issues. Malfunctions occurred solely in less recent devices, regardless of photon dose.

Funding Acknowledgement

Type of funding source: None

A randomized in vitro evaluation of transient and permanent cardiac implantable electronic device malfunctions following direct exposure up to 10 Gy

BACKGROUND AND PURPOSE

High-dose 6‑MV radiotherapy may cause cardiac implantable electronic devices (CIEDs) to malfunction. To assess CIED malfunctions resulting from direct exposure up to 10 Gy, 100 pacemakers (PMs) and 40 implantable cardioverter-defibrillators (ICDs) were evaluated.

MATERIALS AND METHODS

CIEDs underwent baseline interrogation. In ICDs, antitachycardia therapies were disabled via the programmer while the detection windows were left enabled. A computed tomography (CT) scan was performed to build the corresponding treatment plan. CIEDs were "blinded" and randomized to receive single doses of either 2, 5, or, 10 Gy via a 6-MV linear accelerator (linac) in a water phantom. Twenty-two wireless telemetry-enabled CIEDs underwent a real-time session, and their function was recorded by the video camera in the bunker. The CIEDs were interrogated after exposure and once monthly for 6 months.

RESULTS

During exposure, regardless of dose, 90.9% of the CIEDs recorded electromagnetic interference, with 6 ICDs (27.3%) reporting pacing inhibition and inappropriate arrhythmia detections. After exposure, a backup reset was observed in 1 PM (0.7% overall, 1% among PMs), while 7 PMs (5% overall, 7% among PMs) reported battery issues (overall immediate malfunction rate was 5.7%). During follow-up, 4 PMs (2.9% overall; 4% among PMs) and 1 ICD (0.7% overall; 2.5% among ICDs) reported abnormal battery depletion, and 1 PM (0.7% overall; 1% among PMs) reported a backup reset (overall late malfunction rate was 4.3%).

CONCLUSION

Apart from transient electromagnetic interference, last-generation CIEDs withstood direct 6‑MV exposure up to 10 Gy. Permanent battery or software errors occurred immediately or later only in less recent CIEDs.

P1134Cardiac pacemakers and transient electromagnetic interferences during radiotherapy courses: a multicentre, real-time, in-vitro evaluation

Funding Acknowledgements

None

Background

The effects of high dose oncologic radiotherapy (RT) on cardiac pacemakers (PMs), at even less than 6 MV power, are unpredictable, depending on multiple factors. Normal PM function may be impaired during direct exposure, due to electromagnetic interferences (EMIs). Potentially life-threatening malfunctions may occur, expecially in PM-dependent patients, and both manufacturers and guidelines discourage direct exposure.

Purpose

To evaluate transient EMI-related PM malfunctions during direct exposure to doses up to 10 Gy during radiotherapy course, 17 wireless-telemetry-enabled PMs with sufficient residual battery charge for the purpose of the study (at least 4 months to elective replacement indicator, E.R.I.) were evaluated in three different centres.

Methods

All PMs underwent baseline interrogation. Single chamber devices were programmed in the VVI/40 mode while dual or triple chamber devices were programmed in the DDD/40 mode. To avoid the "run-away" phenomenon during exposure rate-adaptive function was disabled. A centering computed tomography was performed to build the corresponding treatment plan and the PMs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a 6 MV linear accelerator in a homemade water phantom (600 Um/min). The effective dose received by the PMs was randomly assessed by an in-vivo dosimetry. During RT course, the devices were observed in a real-time session using manufacturer specific equipment, and PM function (pacing and sensing, programmed parameters) was recorder by a video camera in the bunker throughout the entire radiation exposure.

Results

During RT course, 13 PMs (76.5%) recorded not clinically relevant minor transient  EMIs, and no atrial and/or ventricular oversensing nor base-rate-pacing inhibition were observed. Only 4 PMs (23.5%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. Transient EMI-related malfunctions were observed regardless of either 2, 5 or 10 Gy exposure.

Conclusions

Minor, not clinically relevant EMI-related interferences were observed in most of the PMs during direct exposure. Nevertheless, to avoid potentially life-threatening PM malfunctions, magnet application on the PM pocket site or reprogramming are still suggested in PM-dependent (high risk) patients ongoing even low energy RT exposure.

910Noise-related malfunctions in modern ICDs during oncologic radiotherapy: a multicentre, real-time, in-vitro observation

Funding Acknowledgements

None

Background

Direct photon exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered not recommended, or even unsafe, by manufacturers and guidelines. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and electromagnetic interferences (EMIs) may present during exposure.

Purpose

To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy radiotherapy, 36 contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (E.R.I.) were evaluated in a realtime in-vitro session.

Methods

All ICDs had baseline interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber devices were programmed in the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still working. A centering computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy course, the devices were observed in a real-time session using manufacturer specific programmer, and ICD function (pacing, sensing, programmed parameters, detection) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure.

Results

During radiotherapy course, almost all ICDs (90.9%) recorded major or minor transient EMIs. On detail, 16 ICDs (44.4%) reported EMI-related atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. 16 ICDs (44.4%) recorded not clinically relevant minor EMIs, and no detections were observed. Only 4 ICDs (11.2%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. EMI-related malfunctions occurred regardless of either 2, 5 or 10 Gy photon beam exposure.

Conclusions

Transient EMIs were observed in most of the contemporary ICDs. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or reprogramming in the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

P551Permanent cardiac implantable device damage during direct photon exposure for oncologic radiotherapy: a multicentre, in-vitro observation

Funding Acknowledgements

None

Backgroung. Direct photon exposure of cardiac implantable devices (CIEDs), both pacemakers (PMs) or implantable cardioverter defibrillators (ICDs), during oncologic radiotherapy (RT) courses may transiently or permanently affect normal device function.

Purpose

To evaluate CIED damage by direct exposure to doses up to 10 Gy in oncologic RT, commonly considered unsafe or even potentially harmful, 206 CIEDs (143 PMs and 63 ICDs) from three different centres, with at least 4 months to Elective Replacement Indicator (E.R.I.) were observed.

Methods. All CIEDs had a baseline telemetry interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber ones were programmed in the DDD/40 mode. Rate adaptive function was disabled. In ICDs, antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation window left enabled. A centering Computed Tomography was performed to build the corresponding treatment plan and CIEDs were blinded randomized to receive either 2, 5 or 10 Gy (direct exposure) by a 6 MV linear accelerator in a home-made water phantom. An in-vivo dosimetry randomly assessed the effective dose received by the CIEDs. All CIEDs were interrogated immediately after exposure and monthly during a three-month follow-up.

Results. Immediately after photon exposure, no changes in device setting or software errors were observed in 205 CIEDs (99·5%). Reset to emergency back-up mode was observed in a PM (0·49% overall; 0·7% among PMs). Seven PMs reached the E.R.I immediately after exposure (3·4% overall; 4·9% among PMs). Sixteen ICDs (7·8% overall; 25·4% among ICDs) reported multiple ventricular  tachycardia/fibrillation detections stored in the device memory. During follow-up, a non-reprogrammable software reset (emergency backup VVI/65 mode) was observed in one PM after a single dose of 2 Gy (0·49% overall; 0.7% among PMs), whereas an abnormal battery drain was observed in 6 PMs (2.9% overall; 4.2% among PMs). No battery issues were observed in ICDs. All reported events occurred regardless of either 2, 5, or 10 Gy direct exposure. Malfunctions were observed in only older CIEDs.

Conclusions. Recent CIEDs have shown to be safe during oncologic RT, withstanding direct exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturers statements and clinical guidelines. Malfunctions occurred solely in older devices.

Successful treatment with rivaroxaban of an extended deep vein thrombosis complicated by pulmonary embolism in a patient with familial antithrombin III deficiency: a case report

BACKGROUND

Patients with low levels of antithrombin III (AT III) are at an increased risk of developing arteriovenous thromboembolic disease.

CASE SUMMARY

We report a case of a 28-year-old woman who presented with a 1-week history of spontaneous right calf pain and swelling. A heterozygous AT III deficiency, phenotypically expressed as deep vein thrombosis, was reported in the patient's mother and sister. Blood workup revealed residual AT III activity at 58% with normal protein C and protein S levels. Computed tomographic angiography (CTA) revealed subsegmental bilateral pulmonary embolism (PE) and deep vein thrombosis in the right leg extending into the inferior vena cava up to the confluence of the left renal vein. Placement of an inferior vena cava filter was not considered. Given the patient's haemodynamic stability, anticoagulant therapy with 15 mg of rivaroxaban twice a day was initiated instead. Echocardiography after 10 days of treatment revealed complete resolution of the thrombus located in the inferior vena cava, while CTA revealed complete resolution of the PE.

DISCUSSION

Patients with AT III deficiency are likely to be heparin-resistant and will require higher heparin doses or the administration of AT III replacement therapy for the treatment of thrombosis, both of which are associated with an increased risk for haemorrhagic complications. Direct factor Xa inhibition by rivaroxaban provided an alternative mechanism for anticoagulation, which was found to be particularly useful in this patient with familial AT III deficiency, deep vein thrombosis, and PE.

P1583 Usefulness of remote intrathoracic impedance alerts for echo-guided CRT optimization

Background

Cardiac resynchronisation therapy (CRT) is a strong recommendation in heart failure (HF) patients having sinus rhythm, left bundle branch block, QRS duration ≥ 120 ms and left ventricular (LV) ejection fraction (EF) ≤ 35%, despite optimized medication. Echocardiographic parameters still have a controversial role in the selection of patients ongoing CRT, and no single parameter is recommended to identify a positive CRT response. Even their role in the management after implantation remains still troubleshooting. Atrioventricular (AV) and interventricular (VV) delay reprogramming could be a variable that may influence CRT outcome and, although a systematic AV and VV optimization is not required, it could be useful in selected patients. Remote monitoring networks allow HF patients having a CRT device to be constantly monitored, and notifications of some intrathoracic impedance indexes, may be helpful in the management of HF patients.

Purpose

To evaluate the usefulness of intrathoracic impedance notifications in the selection of HF patients to have echo-guided AV and/or VV delays optimization, the following study was undertaken.

Methods

27 CRT patients having an intrathoracic impedance enabled remote monitoring, with at least one impedance notification during the first six months from implantation, were considered for study. The primary endpoint was a composite of improvement in NYHA functional class and EF, reduction of LV end-systolic volume and rehospitalization for decompensated HF. Secondary endpoint was the effectiveness of echo-guided dealys optimization based on intrathoracic impedance alerts. The AV delay optimization was mainly driven by mitral inflow pattern, whereas VV delay optimization was guided by the assessment of LV synchrony using color Tissue Doppler Imaging (TDI). Patients were weekle evaluated through remote monitoring network over a six-month follow-up. LVEF and LV end-systolic volume were determind at baseline and after six months.

Results

After the six-month follow-up, an improvement of at least 1 NYHA functional class was obtained in 23 patients (85%), while 2 patients (7.4%) experienced an improvement of two NYHA classes. In 21 Patients (77.7%) LVEF increased at least 5%. Optimization was associated with an average 11.9 ± 6.4% increas in EF, from a mean baseline of 28.2 ± 3.2% to 37.8 ±6.2%. End-systolic volume decreased from 161.56 ± 9.87 ml to 143.22 ± 15.83 ml. Among the 27 patients with impedance alerts at baseline, only 6 (22.2%) reported new notifications during follow-up, with a significant reduction (p < 0.03) after optimization.

Conclusions

Intrathoracic impedance monitoring improved the selection of non responders feasible to have echo-guided AV and/or VV delays optimization. Functional status and LVEF increased. Although time-consuming, this multidisciplinary network may increase close cooperation between electrophysiologist and HF physicians to better manage HF patients having a CRT system implanted.

2410Oncologic radiotherapy-induced implantable cardioverter-defibrillator malfunctions: a real-time, in-vitro evaluation

Background

Direct exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered not recommended, or even unsafe, by manufacturers and guidelines. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and malfunctions may occur during exposure.

Purpose

To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy radiotherapy, 33 contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (E.R.I.) were evaluated in a realtime in-vitro session.

Methods

All ICDs had baseline interrogation. Single chamber ICDs were programmed in the VVI/40 mode and dual or triple chamber ICDs were programmed in the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still active. A centering computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was assessed by an in-vivo dosimetry. During radiotherapy, the devices were observed in a real-time session using manufacturer specific programmer, and ICD function (pacing, sensing, programmed parameters, detection) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure.

Results

During radiotherapy course, almost all ICDs (90.9%) recorded major or minor transient electromagnetic interferences. On detail, 13 ICDs (39.4%) reported atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. 16 ICDs (48.5%) recorded non clinically relevant noise, and no detections were observed. Only 4 ICDs (12.1%) reported neither transient malfunction nor minor noise, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. Malfunctions occurred regardless of either 2, 5 or 10 Gy photon beam exposure.

Conclusions

Transient electromagnetic interferences were observed in most of the contemporary ICDs during radiotherapy course, regardeless of photon dose. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or reprogramming devices in the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

Acknowledgement/Funding

None

P6553Contemporary pacemakers and oncologic radiotherapy courses: a real-time, wireless-enabled observation

Background

The effects of high dose oncologic radiotherapy on cardiac pacemakers (PMs), at even less than 6MV power, are unpredictable, depending on multiple factors. Normal PM function may be impaired during photon exposure, with potentially life-threatening consequences in PM-dependent patients, and, unlike in magnetic resonance imaging setting, both manufacturer statements and guidelines discourage direct exposure.

Purpose

To evaluate transient PM malfunctions by direct exposure to doses up to 10 Gy during radiotherapy course, actually not recommended or considered even unsafe, 17 wireless-telemetry-enabled PMs obtained after upgrade or extraction of the system, with sufficient residual battery charge for the purpose of the study (at least 1 year to elective replacement indicator, E.R.I.) were evaluated in a real-time in-vitro session.

Methods

All PMs underwent baseline interrogation. Single chamber devices were programmed in VVI/40 mode while dual or triple chamber devices were programmed in DDD/40 mode. Rate adaptive function was disabled to avoid the “run-away” phenomenon during exposure. A centering computed tomography was performed to build the corresponding treatment plan and the PMs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the PMs was assessed by an in-vivo dosimetry. During radiotherapy course, the devices were observed in a real-time session using manufacturer specific equipment, and PM function (pacing and sensing, programmed parameters) was recorder by a videocamera in the bunker before (5 minutes), throughout, and after (5 minutes) the entire radiation exposure.

Results

During radiotherapy course, non of the PMs reported spontaneous changes in parameter settings. 13 PMs (76.5%) recorded non clinically relevant minor transient electromagnetic sensing interferences. No atrial and/or ventricular oversensing nor base-rate-pacing inhibition were observed. Only 4 PMs (23.5%) reported neither transient malfunction nor minor noise, withstanding direct radiation exposure. Transient oversensing-related malfunctions were observed regardless of either 2, 5 or 10 Gy exposure.

Conclusions

Minor, non clinically relevant electromagnetic sensing interferences were observed in most of the PMs during direct exposure. Nevertheless, to avoid potentially life-threatening PM malfunctions, magnet application on the PM pocket site or reprogramming in the asynchronous mode are still suggested in PM-dependent patients ongoing even low energy radiotherapy exposure.

Acknowledgement/Funding

None

P2858Cardiac implantable device malfunctions during radiotherapy courses up to 10 Gy: a double-center, prospective, randomized, in-vitro evaluation

Background

Exposure to radiotherapy in patients with cardiac implantable electronic devices (CIEDs), both pacemakers (PMs) or implantable cardioverter defibrillators (ICDs), seems to be still troubleshooting. Unlike magnetic resonance imaging, high dose photon radiation at even less than 6MV power, notoriously a non-neutron-producing setting, may transiently or permanently affect normal device function. Malfunctions may be harmfull and life-threatening in high risk patients, such as PM-dependent or ICD ones.

Purpose

To evaluate CIED malfunctions by direct exposure to doses more than 2Gy in oncologic radiotherapy, 162 CIEDs (116 PMs and 46 ICDs) from two different centers, with at least 4 months to Elective Replacement Indicator (E.R.I.) were evaluated.

Methods

All CIEDs had a baseline telemetry interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber devices were programmed in the DDD/40 mode. Rate adaptive function was disabled. In ICDs, antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation monitor still enabled. To build the corresponding treatment plan a centering Computed Tomography was performed and CIEDs were blinded randomized (4:4:4) to either 2, 5 or 10 Gy direct exposure by a low photon-energy LINAC (6MV) in a water phantom. An in-vivo dosimetry assessed the effective dose received by the CIEDs. All CIEDs had a telemetry-interrogation, using manufacturer specific equipment, immediately after exposure and monthly for a four-month follow-up.

Results

Immediately after exposure, 1 reset to emergency mode was observed in a PM (0.6% overall; 0.9% among PMs)), while 7 PMs reached the E.R.I immediately after exposure (4.3% overall; 6% among PMs). 10 ICDs (6.2% overall; 21.8% among ICDs) reporded multiple ventricular fibrillation detection stored in the device memory. During follow-up, 3 PMs (1.9% overall; 2.6% among PMs) and 1 ICD (0.6% overall; 2.2% among ICDs) reached the E.R.I. and 1 PM (0.6% overall; 0.9% among PMs) switched to emergency mode. All reported events occurred regardless of either 2, 5, or 10 Gy direct exposure. Malfunctions were observed in only older CIEDs.

Conclusions

Our data suggest recent CIEDs withstanding direct oncologic radiotherapy exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturer statements and clinical guidelines. Malfunctions occurred in only older devices.

Acknowledgement/Funding

None

Is shock impedance value alone to be considered a good predictor for shock efficacy in subcutaneous implantable cardioverter defibrillator?

Subcutaneous implantable cardioverter defibrillator (S-ICD) is easy to implant, with poor risks of the patient. However, fat is a poor current conductor and increases defibrillation threshold. As shock impedance alone should not be considered a good efficacy predictor of an S-ICD system, an X-ray latero-lateral view for lead position should be achieved.

[Nitrates in cardiology: current role and areas of uncertainty]

Nitrates have been commonly used in the therapy of cardiovascular disease for more than 150 years. In spite of this longevity and the popularity of their use, it appears somewhat paradoxical that their use is not consistent among cardiologists, both as to their indications and as to their mode of administration. In part this results from their contradictory pharmacodynamics: when given acutely, their effectiveness is indisputable; however, their long-term efficacy is substantially limited by the development of tolerance and the induction of endothelial dysfunction, which may have negative prognostic implications. This review, reporting the most recent biochemical and pathophysiological acquisitions, re-examines the role of nitrates in cardiovascular medicine, reporting, comparing and commenting international guidelines.

[Comparative in vitro study of various titanium compounds on the immune system]

The "in vitro" immune effects of different Ti compounds on peripheral blood mononuclear cells (PBMC) were determined. The results show that Ti dioxide is not immunotoxic; Ti oxalate is strongly immunotoxic; titanocene inhibits cytokine release but not PBMC proliferation, while Ti ascorbate inhibits TNF-alpha release from PBMC but not that of IFN-gamma. The results show that Ti toxicity depends on speciation.

[In vitro effects of hexavalent and tetravalent tellurium on immune functions]

The "in vitro" immune effects of K2TeO3xH2O (Te IV) and K2TeO4x2H2O (Te VI) on peripheral blood mononuclear cells (PBMC) was determined. Te(IV) inhibited PBMC proliferation and IFN-gamma, IL-5 and TNF-alpha release from PBMC more than Te (VI).