Dynamic Myocardial Ischemia Caused by Circumflex Artery Stenosis Detected by a New Implantable Left Atrial Pressure Monitoring Device

The V-LAP System for Remote Left Atrial Pressure Monitoring of Patients with Heart Failure: Remote Left Atrial Pressure Monitoring

OBJECTIVE

Patients with heart failure (HF) are at an increased risk of hospital admissions. The aim of this report is to describe the feasibility, safety and accuracy of a novel wireless left atrial pressure (LAP) monitoring system in HF patients.

METHODS

The V-LAP Left Atrium Monitoring systEm for Patients With Chronic sysTOlic & Diastolic Congestive heart Failure (VECTOR-HF) study is a prospective, multicenter, single-arm, open-label, first-in human clinical trial to assess the safety, performance and usability of the V-LAP system (Vectorious Medical Technologies, Ltd) in NYHA Class III HF patients. The device was implanted in the inter-atrial septum via a percutaneous, trans-septal approach, guided by fluoroscopy and echocardiography. Primary endpoints included the successful deployment of the implant, ability to perform initial pressure measurements and safety outcomes.

RESULTS

To date, 24 patients were implanted with the LAP monitoring device. No device-related complications have occurred. LAP was reported accurately, agreeing well with wedge pressure at 3 months (Lin's CCC=0.850). After 6 months, NYHA class improved in 40% of the patients (95% CI =16.4%-63.5%), while 6-minute walk test distance had not changed significantly (313.9 ± 144.9 vs. 232.5 ± 129.9 meters, p=0.076).

CONCLUSION

The V-LAP left atrium monitoring system appears to be safe and accurate.

A rise in left atrial pressure detected by the V-LAP™ system for patients with heart failure during the coronavirus disease 2019 pandemic

During the coronavirus disease 2019 (COVID‐19) pandemic, many patients refrained from inpatient medical care. For those inflicted with heart failure (HF), the risk of repeat hospitalizations is particularly high in case of infection. This presents an important opportunity for remote monitoring of haemodynamic data for these patients, in order to detect and treat accordingly. The aim of the present case is to report of the first measurements of a novel wireless left atrial pressure (LAP) monitoring system, the V‐LAP™ (Vectorious Medical Technologies, Ltd), during the COVID‐19 pandemic. The V‐LAP™ Left Atrium Monitoring systEm for Patients With Chronic sysTOlic & Diastolic Congestive heart Failure (VECTOR‐HF) is a first‐in‐man clinical study assessing the safety and feasibility of the V‐LAP™ monitoring system. Our first patient, a 59‐year‐old man with severe ischaemic cardiomyopathy (left ventricular ejection fraction −30%) was enrolled prior to the COVID‐19 outbreak. As per protocol, both the patient and the medical team were blinded to the results in the first 3 months after implantation. We were able to witness the LAP during the pandemic, as the patient remained undertreated, demonstrating a gradual increase from a mean pressure of 6.56 to 19.4 mmHg, as well as prominent V waves, before the data became available to the medical team and the patient was treated accordingly. Thereafter, pressures have returned to low values. This case demonstrated the feasibility of remote monitoring of LAP using the V‐LAP™ system, as well as the potential benefit of remote care of HF patients.

Implantable Sensors for Regenerative Medicine

The translation of many tissue engineering/regenerative medicine (TE/RM) therapies that demonstrate promise in vitro are delayed or abandoned due to reduced and inconsistent efficacy when implemented in more complex and clinically relevant preclinical in vivo models. Determining mechanistic reasons for impaired treatment efficacy is challenging after a regenerative therapy is implanted due to technical limitations in longitudinally measuring the progression of key environmental cues in vivo. The ability to acquire real-time measurements of environmental parameters of interest including strain, pressure, pH, temperature, oxygen tension, and specific biomarkers within the regenerative niche in situ would significantly enhance the information available to tissue engineers to monitor and evaluate mechanisms of functional healing or lack thereof. Continued advancements in material and fabrication technologies utilized by microelectromechanical systems (MEMSs) and the unique physical characteristics of passive magnetoelastic sensor platforms have created an opportunity to implant small, flexible, low-power sensors into preclinical in vivo models, and quantitatively measure environmental cues throughout healing. In this perspective article, we discuss the need for longitudinal measurements in TE/RM research, technical progress in MEMS and magnetoelastic approaches to implantable sensors, the potential application of implantable sensors to benefit preclinical TE/RM research, and the future directions of collaborative efforts at the intersection of these two important fields.

Implantable Hemodynamic Monitoring for Heart Failure Patients

Rates of heart failure hospitalization remain unacceptably high. Such hospitalizations are associated with substantial patient, caregiver, and economic costs. Randomized controlled trials of noninvasive telemedical systems have failed to demonstrate reduced rates of hospitalization. The failure of these technologies may be due to the limitations of the signals measured. Intracardiac and pulmonary artery pressure-guided management has become a focus of hospitalization reduction in heart failure. Early studies using implantable hemodynamic monitors demonstrated the potential of pressure-based heart failure management, whereas subsequent studies confirmed the clinical utility of this approach. One large pivotal trial proved the safety and efficacy of pulmonary artery pressure-guided heart failure management, showing a marked reduction in heart failure hospitalizations in patients randomized to active pressure-guided management. "Next-generation" implantable hemodynamic monitors are in development, and novel approaches for the use of this data promise to expand the use of pressure-guided heart failure management.

Congestive heart failure with preserved ejection fraction is associated with severely impaired dynamic Starling mechanism

Sedentary aging leads to increased cardiovascular stiffening, which can be ameliorated by sufficient amounts of lifelong exercise training. An even more extreme form of cardiovascular stiffening can be seen in heart failure with preserved ejection fraction (HFpEF), which comprises ~40~50% of elderly patients diagnosed with congestive heart failure. There are two major interrelated hypotheses proposed to explain heart failure in these patients: 1) increased left ventricular (LV) diastolic stiffness and 2) increased arterial stiffening. The beat-to-beat dynamic Starling mechanism, which is impaired with healthy human aging, reflects the interaction between ventricular and arterial stiffness and thus may provide a link between these two mechanisms underlying HFpEF. Spectral transfer function analysis was applied between beat-to-beat changes in LV end-diastolic pressure (LVEDP; estimated from pulmonary artery diastolic pressure with a right heart catheter) and stroke volume (SV) index. The dynamic Starling mechanism (transfer function gain between LVEDP and the SV index) was impaired in HFpEF patients (n = 10) compared with healthy age-matched controls (n = 12) (HFpEF: 0.23 ± 0.10 ml·m⁻²·mmHg⁻¹ and control: 0.37 ± 0.11 ml·m⁻²·mmHg⁻¹, means ± SD, P = 0.008). There was also a markedly increased (3-fold) fluctuation of LV filling pressures (power spectral density of LVEDP) in HFpEF patients, which may predispose to pulmonary edema due to intermittent exposure to higher pulmonary capillary pressure (HFpEF: 12.2 ± 10.4 mmHg² and control: 3.8 ± 2.9 mmHg², P = 0.014). An impaired dynamic Starling mechanism, even more extreme than that observed with healthy aging, is associated with marked breath-by-breath LVEDP variability and may reflect advanced ventricular and arterial stiffness in HFpEF, possibly contributing to reduced forward output and pulmonary congestion.

Physician-directed patient self-management of left atrial pressure in advanced chronic heart failure

BACKGROUND

Previous studies suggest that management of ambulatory hemodynamics may improve outcomes in chronic heart failure. We conducted a prospective, observational, first-in-human study of a physician-directed patient self-management system targeting left atrial pressure.

METHODS AND RESULTS

Forty patients with reduced or preserved left ventricular ejection fraction and a history of New York Heart Association class III or IV heart failure and acute decompensation were implanted with an investigational left atrial pressure monitor, and readings were acquired twice daily. For the first 3 months, patients and clinicians were blinded as to these readings, and treatment continued per usual clinical assessment. Thereafter, left atrial pressure and individualized therapy instructions guided by these pressures were disclosed to the patient. Event-free survival was determined over a median follow-up of 25 months (range 3 to 38 months). Survival without decompensation was 61% at 3 years, and events tended to be less frequent after the first 3 months (hazard ratio 0.16 [95% confidence interval 0.04 to 0.68], P=0.012). Mean daily left atrial pressure fell from 17.6 mm Hg (95% confidence interval 15.8 to 19.4 mm Hg) in the first 3 months to 14.8 mm Hg (95% confidence interval 13.0 to 16.6 mm Hg; P=0.003) during pressure-guided therapy. The frequency of elevated readings (>25 mm Hg) was reduced by 67% (P<0.001). There were improvements in New York Heart Association class (-0.7+/-0.8, P<0.001) and left ventricular ejection fraction (7+/-10%, P<0.001). Doses of angiotensin-converting enzyme/angiotensin-receptor blockers and beta-blockers were uptitrated by 37% (P<0.001) and 40% (P<0.001), respectively, whereas doses of loop diuretics fell by 27% (P=0.15).

CONCLUSIONS

Physician-directed patient self-management of left atrial pressure has the potential to improve hemodynamics, symptoms, and outcomes in advanced heart failure. Clinical Trial Registration Information- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00547729.

Direct Left Atrial Pressure Monitoring in Ambulatory Heart Failure Patients

Background— We describe the first human experience with a permanently implantable, direct left atrial pressure (LAP) monitoring system in ambulatory patients with chronic heart failure.

Methods and Results— Eight patients with established heart failure and at least 1 heart failure hospitalization or unplanned visit for parenteral therapy in the last year underwent device implantation under fluoroscopic guidance. All subjects received aspirin 150 mg and clopidogrel 75 mg daily. Subjects measured LAP twice daily and attended a clinic regularly for data upload and device calibration. Right heart catheterization was performed at the time of device implantation and at 12 weeks. The device was implanted in all subjects with no procedural complications. At the 12-week follow-up, 87% of device LAP measurements were within ±5 mm Hg of simultaneous pulmonary capillary wedge pressure readings over a wide range of pressures (1.6 to 71 mm Hg). Net drift corrected by calibration was −0.2±1.9 mm Hg/mo. During short-term follow-up, there were no device-related complications or systemic emboli. There were no deaths, no unplanned heart failure clinic visits, and no admissions for heart failure.

Conclusions— Ambulatory monitoring of direct LAP with a new implantable device was well tolerated, feasible, and accurate at a short-term follow-up. Further follow-up and investigation are warranted to evaluate the clinical utility of LAP monitoring in patients with heart failure.

Device monitoring of intrathoracic impedance: clinical observations from a patient registry

A distinct advantage of implantable device diagnostics is that the data may be made available on a continuous basis, rather than at sporadic intervals associated with clinical testing. Recently, intrathoracic impedance monitoring has also become available in some implantable devices as an index of congestion and thoracic fluid accumulation secondary to decompensated heart failure. Despite the potential advantages, new advances in implantable device diagnostic technology also pose important questions regarding their clinical application. To examine these questions and to generate hypotheses, the relation between daily intrathoracic impedance measurements and other physical measurements or comorbidities was studied. A retrospective review was performed of 25 patients who previously underwent implantation of a cardiac resynchronization therapy/defibrillator device with the capability to continuously monitor intrathoracic impedance. This limited scope analysis demonstrated that daily measurement of intrathoracic impedances might reveal the intrinsic relations between heart failure decompensation and the onset of atrial and ventricular arrhythmias. Abnormal patterns of intrathoracic impedance that has increased and plateaued after implant may indicate worsening heart failure. The severity of congestive heart failure at the time of interrogation may correlate with device-based impedance measurements. Weight, sex, and body index may have a limited impact on impedance, and the lowest impedances may be seen in older patients. Patients with severe pulmonary disease may present with unique daily impedance profiles. Finally, daily impedance may have unpredictable relations with other clinical markers of heart failure. In summary, intrathoracic impedance represents a clinically useful diagnostic tool that can increase our understanding of a dynamic disease state on an individual patient basis.