Search

Emanuela Marcelli,1,* Laura Cercenelli,1,* Barbara Bortolani,1 Saverio Marini,2 Luca Arfilli,3 Alessandro Capucci,4 Gianni Plicchi5 1eDIMES Lab-Laboratory of Bioengineering, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, Bologna, Italy; 2Ars Medica: Associazione Medico-Chirurgica Della Gallura, Olbia, Italy; 3Villa Laura Ospedale Privato Accreditato, Bologna, Italy; 4Abcardio Cardiological Center, Bologna, Italy; 5TRE ESSE Progettazione Biomedica S.r.l., Bologna, 40138, Italy*These authors contributed equally to this workCorrespondence: Laura CercenelliLaboratory of Bioengineering, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), Alma Mater Studiorum University of Bologna, c/o S. Orsola Malpighi-Hospital, via Massarenti 9, Bologna, 40138, ItalyTel +39 0516364603Fax +39 0516364603Email laura.cercenelli@unibo.itBackground: Venous congestion can be quantified by central venous pressure (CVP) and its monitoring is crucial to understand and follow the hemodynamic status of patients with cardio-respiratory diseases. The standard technique for CVP measurement is invasive, requiring the insertion of a catheter into a jugular vein, with potential complications. On the other hand, the current non-invasive methods, mainly based on ultrasounds, remain operator-dependent and are unsuitable for use in the home environment. In this paper, we will introduce a novel, non-invasive device for the hospital, office and home assessment of CVP.Methods: After describing the measurement concept, we will report a preliminary experimental study enrolling 5 voluntary healthy subjects to evaluate the VenCoM measurements’ repeatability, and the system’s capability in measuring small elicited venous pressure variations (2 mmHg), as well as an induced venous hypertension within a pathological range (12÷ 20 mmHg).Results: The experimental measurements showed a repeatability of ± 1mmHg. The VenCoM device was able to reliably detect the elicited venous pressure variations and the simulated congestive status.Discussion and Conclusion: The proposed non-invasive VenCoM device is able to provide a fast and repeatable CVP estimate, having a wide spectrum of potential clinical applications, including the monitoring of venous congestion in heart failure patients and in subjects with renal and hepatic dysfunction, as well as pulmonary hypertension (PH) that can be extended to pneumonia COVID-19 patients even after recovery. The device needs to be tested further on a large sample size of both healthy and pathological subjects, to systematically validate its reliability and impact in clinical setting.Keywords: central venous pressure, pulmonary artery pressure, heart failure, non-invasive device, home monitoring, COVID-19, cardiovascular measurements

The quest to discover effective methodologies to monitor the course of disease and response to therapeutic agents in patients with chronic heart failure continues. Clinical trials of specific therapeutic agents have shown efficacy in large groups of patients, but the outcome even with the most effective agents is recognized to be heterogeneous for largely unexplained reasons. The idea that the treatment of individual patients with heart failure could be guided by serial measurements of surrogate end points for mortality and morbidity remains attractive to clinicians. A new approach for clinicians is the guiding of heart failure care by hemodynamic implantable sensors, and in this paper, a brief review of the implantable technologies available to assess cardiac function for monitoring the course of chronic heart failure (CHF) is presented. Early results suggest that measurements arising from these implantable devices should help in guiding the long-term management of CHF patients. Careful consideration of measurements to make, end points to assess, and therapy in control patients will be essential in validating new approaches. [ABSTRACT FROM AUTHOR]

Previous experimental studies demonstrated that in normal hearts, Peak Endocardial Acceleration (PEA), during isovolumic contraction phase, measured with an endocardial sensor (Best, Sorin) in the right ventricle (RV), tracks changes of left ventricular (LV) contractility. Aim of the study: To assess if PEA also tracks LV contractility changes in ischemic hearts resulting from coronary microembolizations (ME). Methods: Under general anaesthesia, six adult beagle dogs (12 ± 2 kg) were instrumented for chronic monitoring of LV pressure, ECG and PEA. Latex beads mixed with fluoroscopy dye were injected into the circumflex coronary artery to cause LV ischemia. Before and after ME, incremental dobutamine infusions were performed to evaluate the contractile response to adrenergic stimulation. Results: A significant correlation between PEA and LVdP/dtmax was observed before and after ME. Such a strong correlation was maintained even during adrenergic stimulation (r = 0.83 to 0.99, p < 0.001). The sensor PEA appears to be an effective means for the chronic monitoring of the mechanical function of ischemic hearts. [ABSTRACT FROM AUTHOR]

Background: As the myocardium contracts isometrically, it generates vibrations that can be measured with an accelerometer. The vibration peak, peak endocardial acceleration (PEA), is an index of contractility.Objective: To evaluate the feasibility of PEA measured by the cutaneous precordial application of the accelerometer sensor; and to assess the usefulness of PEA monitoring during pharmacological stress echocardiography.Design: Feasibility study.Setting: Stress echo laboratory.Patients: 34 consecutive patients underwent pharmacological stress (26 with dipyridamole; 8 with dobutamine) and PEA monitoring simultaneously.Interventions: A microaccelerometer was positioned in the precordial region and PEA was recorded. Dipyridamole was infused up to 0.84 mg/kg in 10 minutes, and dobutamine up to 40 microg/kg/min in 15 minutes.Results: A consistent PEA signal was obtained in all patients. Overall mean (SD) baseline PEA was 0.26 (0.15) g (g = 9.8 m/s(2)), increasing to 0.5 (0.36) g at peak stress (+0.24 g, 95% confidence interval (CI) 0.14 to 0.34 g; p < 0.01). PEA increased from 0.26 (0.16) to 0.37 (0.25) g in the dipyridamole group (+0.11 g, 95% CI 0.08 to 0.16 g; p < 0.01), and from 0.29 (0.1) to 0.93 (0.37) g in the dobutamine group (+0.64 g, 95% CI 0.37 to 0.91 g; p < 0.01).Conclusions: Using precordial leads this method offers potential for diagnostic application in the short term monitoring of myocardial function. PEA monitoring is feasible during pharmacological stress and documents left ventricular inotropic response quantitatively in a non-invasive and operator independent fashion. [ABSTRACT FROM AUTHOR]

A study was carried out to determine whether variations in the respiration rate during physical exercise could be used as a physiological variable in controlling the rate of an implanted pacemaker. The relation between respiration rate and heart rate was significantly correlated in 73 patients (19 with normal lung function, four with restrictive pulmonary disease, and 50 with obstructive airways disease) during repeated calibrated ergometric tests; no significant differences were found between the subgroups. An external computerised programmable system with algorithm control activated by a radio frequency system was used to vary the cardiac stimulation rate in relation to respiration rate in 11 patients implanted with ventricular inhibited pacemakers. In addition, a prototype programmable pacemaker dependent on respiration rate was implanted in two patients. Maximum values of oxygen uptake, minute ventilation, and work time were increased during the exercise stress tests when the variable cardiac pacing rate was used. Thus respiration rate appears to be a valid and stable physiological variable for controlling the cardiac stimulation rate in order to improve cardiac output in patients dependent on pacemakers. [ABSTRACT FROM PUBLISHER]

In the present study an attempt to evaluate the efficacy of echography as a diagnostic tool has been made. A total of 52 patients (chronic pancreatitis (42); pancreatic cysts (three); and carcinoma of the pancreas (seven)) were studied and the results compared with those from other diagnostic techniques. In 65.7% of chronic pancreatitis patients, and in all cases of carcinoma of the pancreas, echography provided evidence of pancreatic abnormality but in no case could an unambiguous diagnosis of the disease be made. However, in all cases of pancreatic cyst, echography gave precise and unequivocal diagnostic information. There was good agreement between the echographic picture and surgical findings. Cholangiography and duodenography indicated duodenal and choledochal compression in a high proportion of cases in which echography revealed enlargement of the head of the pancreas. It is concluded that echography is a simple, safe, and valuable addition to the techniques available for studying the pancreas. [ABSTRACT FROM PUBLISHER]

As the myocardium contracts isometrically, it generates vibrations that are transmitted throughout the heart. These vibrations can be measured with an implantable microaccelerometer located inside the tip of an otherwise conventional unipolar pacing lead. These vibrations are, in their audible component, responsible for the first heart sound. The aim of this study was to evaluate, in man, the clinical feasibility and reliability of intracavity sampling of Peak Endocardial Acceleration (PEA) of the first heart sound vibrations using an implantable tip mounted accelerometer. We used a unidirectional accelerometer located inside the stimulating tip of a standard unipolar pacing lead: the sensor has a frequency response of DC to 1 kHz and a sensitivity of 5 mV/G (G = 9.81 m/s-2). The lead was connected to an external signal amplifier with a frequency range of 0.05-1,000 Hz and to a peak-to-peak detector synchronized with the endocardial R wave scanning the isovolumetric contraction phase. Following standard electrophysiological studies, sensor equipped leads were temporarily inserted in the RV of 15 patients (68 +/- 15 years), with normal regional and global ventricular function, to record PEA at rest, during AAI pacing, during VVI pacing, and during dobutamine infusion (up to 20 microg/kg per min). PEA at baseline was 1.1 G +/- 0.5 (heart rate = 75 +/- 14 beats/min) and increased to 1.3 G +/- 0.9 (P = NS vs baseline) during AAI pacing (heart rate = 140 beats/min) and to 1.4 G +/- 0.5 (P = NS vs baseline) during VVI pacing (heart rate = 140 beats/min). Dobutamine infusion increased PEA to 3.7 G +/- 1.1 (P < 0.001 vs baseline), with a heart rate of 121 +/- 13 beats/min. In a subset of three patients, simultaneous hemodynamic RV monitoring was performed to obtain RV dP/dtmax, whose changes during dobutamine and pacing were linearly related to changes in PEA (r = 0.9; P < 0.001). In conclusion, the PEA recording can be consistently and safely obtained with an implantable device. Pharmacological inotropic stimulation, but not pacing induced chronotropic stimulation, increases PEA amplitude, in keeping with experimental studies, suggesting that PEA is an index of myocardial contractility. Acute variations in PEA are closely paralleled by changes in RV dP/dtmax, but are mainly determined by LV events. The clinical applicability of the method using RV endocardial leads and an implantable device offers potential for diagnostic applications in the long-term monitoring of myocardial function in man. [ABSTRACT FROM AUTHOR]

In chronic heart failure (CHF) continuous hemodynamic monitoring could provide detailed information on patients' status that may be helpful in their day-to-day management and superior to single measurements obtained at follow–up. Experimental studies have shown that in normal hearts Peak Endocardial Acceleration during isovolumic contraction phase (PEAI) is correlated to Left Ventricular (LV) dP/dtmax changes, while during isovolumic relaxation (PEAII) is correlated to LVdP/dtmin.Aim of the study to demonstrate the capability of an EA sensor to monitor systolic and diastolic impairment in a CHF animal model. Methods Under general anaesthesia 4 adult beagle dogs (12±2kg) were instrumented for chronic monitoring of LV pressure, ECG and EA. Experimental cardiac dysfunction was induced by coronary microembolization (ME) with 1.5 to 2 cc of 45 μM latex beads mixed with fluoroscopy dye. Results In all dogs about 3 months after ME, systolic and diastolic parameters of both LVdP/dt and PEA showed a marked deterioration of cardiac function. Conclusions The EA sensor appears an effective means to monitor systolic and diastolic impairment in CHF animal model. PEA has been extensively used in pacemaker technology for human application and this experimental finding brings new important potential implications to monitor myocardial performance of failing hearts. [ABSTRACT FROM PUBLISHER]

As alternative to standard Doppler echocardiographic methods, an implantable hemodynamic sensor to measure Peak Endocardial Acceleration (PEA) signal may guide CRT optimisation and reprogramming not only at implant time but also in the follow-up. A new method based on the assessment of the area of PEA curve (PEAarea) versus AV delay (AVD) is proposed to program the optimal CRT configuration. During AVD scanning, PEA depends both on A-wave transmitral flow, directly linked to mitral leaflets opening, and on contractility (Left Ventricle (LV) dP/dtmax): a wider PEAarea corresponds to a greater improvement of cardiac function.Aim of the study to evaluate a new method to optimise CRT pacing configuration by maximizing the PEAarea during AVD scanning. Methods a biventricular pacemaker (Living CHF, Sorin) connected to a PEA sensor lead was implanted in 4 patients with impaired LV function (NYHA class III or IV, QRS>150ms). At each pacing configuration (LV,BiV0,LR12,LR40,RL12,RL40), AVD scanning ranging from 60 to 220 ms was performed. A pressure catheter (CD-Leycom) inserted in the LV was used to provide LVdP/dtmax at each pacing configuration. PEAarea was estimated as the mean of PEA values during AVD scanning and for each pacing configuration it was compared to the mean of LVdP/dtmax values during AVD scanning. Results: In all patients the optimal pacing configuration suggested by the maximum value of PEAarea corresponded to the greatest hemodynamic improvement, as indicated by LV dP/dtmax. Conclusions PEAarea is an helpful and innovative parameter to automatically guide optimisation of CRT configuration at implant and during follow-up. The maximization of PEAarea reflects an enhancement of both transmitral Doppler flow and contractility. [ABSTRACT FROM PUBLISHER]

In CRT follow-up, when heart remodelling occurs, what is lacking is a means for a continuous monitoring of individual responses to automatically guide, when it is necessary, an optimal reprogramming of pacing configuration.The area of Peak Endocardial Acceleration (PEAarea) curve versus AV delay (AVD) depends on changes of both transmitral Doppler flow and contractility. Consequently the selection of CRT configuration corresponding to the maximum PEAarea allows to obtain the greatest hemodynamic benefit at implant and during the follow-up.Aim of the study to evaluate individual response to CRT during follow-up by the assessment of PEAarea at different pacing configurations. Methods In 8 patients with impaired LV function (NYHA class III or IV and QRS>150ms) a biventricular pacemaker (Living CHF, Sorin), connected to a right ventricular lead microaccelerometer sensor to record the PEA signal, was implanted. At implant and 3 months later, for each pacing configuration (BiV0, LV, LR20,LR40,RL20,RL40), AVD scanning (ranging from 60 to 300 ms) was performed and PEA was continuously recorded. PEAarea was calculated as the mean of PEA values during AVD scanning. Results At 3 months follow-up, in 4 patients PEAarea method confirmed the optimal pacing configurations selected at implant time, in 2 patients the optimal pacing configuration was changed and 2 patients resulted non responder (n.r.). Conclusions PEA signal versus AVD scanning may be a valid means to assess CRT response and to guide CRT reprogramming during follow-up. [ABSTRACT FROM PUBLISHER]

Abstract: In implantable medical devices (IMDs), the need of telemetry systems able to provide wireless bidirectional communication to interrogate and remotely program the device, as well as to monitor the physiological status of the patient, is growing. The object of the present study was to evaluate a new hermetic antenna for wireless short-range transmission system for IMDs which would assure reliable long-term functioning due to the high level of hermeticity of antenna''s housing that limits the influence of body tissue environment on transmitted signals. Experimental tests were conducted on three different prototypes to evaluate the most efficient antenna configuration for transmission both in the air and through a mixture simulating the human thorax. Further tests were performed to assess the influence of electro-catheters connected to IMDs on transmitted signals. Results showed that the hermetic antenna guarantees a good wireless transmission both in the air and through the human thorax simulator. The results also show that the presence of an electro-catheter can influence the effective radiated power (ERP) transmitted depending on its position in relation to the telemetric circuitry. Both a controlled increase of the ERP without exceeding the limits imposed by rules and the optimization of the tuning between the antenna and the transmitter can assure a reliable short-range transmission (several meters) using the new hermetic antenna proposed. [Copyright &y& Elsevier]