1
|
Longitudinal Validation of Right Ventricular Pressure Monitoring for the Assessment of Right Ventricular Systolic Dysfunction in a Large Animal Ischemic Model. Crit Care Explor 2023; 5:e0847. [PMID: 36699251 PMCID: PMC9851694 DOI: 10.1097/cce.0000000000000847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Right ventricular (RV) dysfunction is a major cause of morbidity and mortality in intensive care and cardiac surgery. Early detection of RV dysfunction may be facilitated by continuous monitoring of RV waveform obtained from a pulmonary artery catheter. The objective is to evaluate the extent to which RV pressure monitoring can detect changes in RV systolic performance assess by RV end-systolic elastance (Ees) following the development of an acute RV ischemic in a porcine model. HYPOTHESIS RV pressure monitoring can detect changes in RV systolic performance assess by RV Ees following the development of an acute RV ischemic model. METHODS AND MODELS Acute ischemic RV dysfunction was induced by progressive embolization of microsphere in the right coronary artery to mimic RV dysfunction clinically experienced during cardiopulmonary bypass separation caused by air microemboli. RV hemodynamic performance was assessed using RV pressure waveform-derived parameters and RV Ees obtained using a conductance catheter during inferior vena cava occlusions. RESULTS Acute ischemia resulted in a significant reduction in RV Ees from 0.26 mm Hg/mL (interquartile range, 0.16-0.32 mm Hg/mL) to 0.14 mm Hg/mL (0.11-0.19 mm Hg/mL; p < 0.010), cardiac output from 6.3 L/min (5.7-7 L/min) to 4.5 (3.9-5.2 L/min; p = 0.007), mean systemic arterial pressure from 72 mm Hg (66-74 mm Hg) to 51 mm Hg (46-56 mm Hg; p < 0.001), and mixed venous oxygen saturation from 65% (57-72%) to 41% (35-45%; p < 0.001). Linear mixed-effect model analysis was used to assess the relationship between Ees and RV pressure-derived parameters. The reduction in RV Ees best correlated with a reduction in RV maximum first derivative of pressure during isovolumetric contraction (dP/dtmax) and single-beat RV Ees. Adjusting RV dP/dtmax for heart rate resulted in an improved surrogate of RV Ees. INTERPRETATION AND CONCLUSIONS Stepwise decreases in RV Ees during acute ischemic RV dysfunction were accurately tracked by RV dP/dtmax derived from the RV pressure waveform.
Collapse
|
2
|
Lionetti V, Romano SL, Bianchi G, Bernini F, Dushpanova A, Mascia G, Nesti M, Di Gregorio F, Barbetta A, Padeletti L. Impact of acute changes of left ventricular contractility on the transvalvular impedance: validation study by pressure-volume loop analysis in healthy pigs. PLoS One 2013; 8:e80591. [PMID: 24260431 PMCID: PMC3834044 DOI: 10.1371/journal.pone.0080591] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/06/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The real-time and continuous assessment of left ventricular (LV) myocardial contractility through an implanted device is a clinically relevant goal. Transvalvular impedance (TVI) is an impedentiometric signal detected in the right cardiac chambers that changes during stroke volume fluctuations in patients. However, the relationship between TVI signals and LV contractility has not been proven. We investigated whether TVI signals predict changes of LV inotropic state during clinically relevant loading and inotropic conditions in swine normal heart. METHODS The assessment of RVTVI signals was performed in anesthetized adult healthy anesthetized pigs (n = 6) instrumented for measurement of aortic and LV pressure, dP/dtmax and LV volumes. Myocardial contractility was assessed with the slope (Ees) of the LV end systolic pressure-volume relationship. Effective arterial elastance (Ea) and stroke work (SW) were determined from the LV pressure-volume loops. Pigs were studied at rest (baseline), after transient mechanical preload reduction and afterload increase, after 10-min of low dose dobutamine infusion (LDDS, 10 ug/kg/min, i.v), and esmolol administration (ESMO, bolus of 500 µg and continuous infusion of 100 µg·kg-1·min-1). RESULTS We detected a significant relationship between ESTVI and dP/dtmax during LDDS and ESMO administration. In addition, the fluctuations of ESTVI were significantly related to changes of the Ees during afterload increase, LDDS and ESMO infusion. CONCLUSIONS ESTVI signal detected in right cardiac chamber is significantly affected by acute changes in cardiac mechanical activity and is able to predict acute changes of LV inotropic state in normal heart.
Collapse
Affiliation(s)
- Vincenzo Lionetti
- Laboratory of Medical Science, Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione CNR/Regione Toscana “G. Monasterio”, Pisa, Italy
- * E-mail:
| | - Simone Lorenzo Romano
- Laboratory of Medical Science, Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Giacomo Bianchi
- Laboratory of Medical Science, Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
- Fondazione CNR/Regione Toscana “G. Monasterio”, Pisa, Italy
| | - Fabio Bernini
- Laboratory of Medical Science, Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Anar Dushpanova
- Laboratory of Medical Science, Institute of Life Sciences, Scuola Superiore Sant’Anna, Pisa, Italy
| | - Giuseppe Mascia
- Department of Medical and Surgical Critical Care, University of Florence, Florence, Italy
| | - Martina Nesti
- Department of Medical and Surgical Critical Care, University of Florence, Florence, Italy
| | | | | | - Luigi Padeletti
- Department of Medical and Surgical Critical Care, University of Florence, Florence, Italy
| |
Collapse
|
3
|
Chuen MJNK, Lip GYH, MacFadyen RJ. Repeated assessment of physical biomeasures or blood biomarkers for the definition of volume status and cardiac loading in LVSD. Biomark Med 2012; 1:355-74. [PMID: 20477380 DOI: 10.2217/17520363.1.3.355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The application of biomarker technology can be usefully implemented in areas where current techniques are inadequate and where a clinical issue, which affects outcome, can be defined. The definition of the loading status of the heart where there is pre-existent impairment of contractile function is a key target. Heart failure is a complex clinical presentation with many varied etiologies, but at the essence of its successful management is the reliable definition of cardiac volume loading. Traditional and many current technological measures are applied to define this relationship, yet their accuracy and performance in individual patients is either basically inadequate or poorly understood and applied. There is a wide range of both physical measurements and blood biomarkers that can be considered to better define this key issue in patients with ventricular systolic impairment. Their performance is considered in detail in this review.
Collapse
|
4
|
Bennett T, Kjellstrom B, Taepke R, Ryden L. Development of Implantable Devices for Continuous Ambulatory Monitoring of Central Hemodynamic Values in Heart Failure Patients. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2005; 28:573-84. [PMID: 15955193 DOI: 10.1111/j.1540-8159.2005.09558.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Care and management of patients with congestive heart failure (CHF) is a major health-care challenge. The value of acute hemodynamic data in assessing heart failure has been questioned in some studies, while more intensive hemodynamic monitoring has been reported to improve patient care in others. A series of patient studies are reported here that were conducted to identify device requirements and verify the feasibility of continuous hemodynamic monitoring in CHF patients and devices for remote transfer and use of these data. METHODS AND RESULTS The results of four separate studies in 68 CHF patients who received systems for chronic hemodynamic monitoring between 1992 and the present are reviewed. One early study was with five patients followed for 7-16 months and another study was with nine patients followed for 4-22 months. A third study included 21 patients followed up to 39 months, and the fourth study included 32 patients implanted in 1998-99 with many of them still in follow-up. These studies support the technical feasibility of implanted devices and the external instrumentation required to transfer and manage the collected data. They also support the long-term stability and accuracy of these systems. Three additional acute studies conducted with 30 patients and chronic data from 53 of the 68 patients with the implanted systems are presented that support the feature included in the newer monitors--the ability to reliably estimate pulmonary artery diastolic pressures from the right ventricular pressure signal. CONCLUSIONS Development of implantable technology to measure several hemodynamic variables in ambulatory CHF patients is feasible. External instrumentation needed to remotely acquire data from the implanted devices has been verified. The potential to eliminate the uncertainties associated with the use of acute, invasive hemodynamics and the ability to evaluate long-term ambulatory hemodynamic patterns is provided. These findings set the stage for determining the potential clinical value of these systems in impacting the care of chronic CHF patients.
Collapse
Affiliation(s)
- Tom Bennett
- Heart Failure Research, Medtronic Inc., MS CW320, 7000 Central Avenue NE, Minneapolis, MN 55432, USA.
| | | | | | | |
Collapse
|
5
|
Cron TA, Pouskoulas CD, Keller DI, Zaugg CE, Buser PT, Pfisterer ME, Osswald S, Hilti P, Schächinger H. Rate response of a closed-loop stimulation pacing system to changing preload and afterload conditions. Pacing Clin Electrophysiol 2003; 26:1504-10. [PMID: 12914629 DOI: 10.1046/j.1460-9592.2003.t01-1-00218.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Closed-loop stimulation (CLS) is a new sensor concept for rate adaptive pacing measuring changes in the unipolar right ventricular impedance, which correlates to changes of the right ventricular contractility and reflects the autonomic nervous innervation of the heart. Some patients do not tolerate the CLS mode because of inappropriate tachycardia, mainly related to postural changes. This study tested if the rate response of the CLS sensor is influenced not only by myocardial contractility but also by rapid changes in right ventricular filling. In 12 patients (10 men, median age 77 years) with a Biotronik Inos(2)-CLS DDDR pacemaker and 14 controls (13 men, median age 59 years) head-up tilt and handgrip testing was performed to provoke rapid changes in pre- and afterload. Tilting the pacemaker patients resulted in a nonphysiological steep increase of the sensor rate (increase >20 beats/min, peak after 1 minute, return to baseline within 2-3 minutes), which was significantly different from the control group, showing only a slight rise in intrinsic heart rate immediately after tilting. Simultaneously to the rapid increase in sensor rate, the pacemaker patients showed a marked orthostatic decline of systolic blood pressure. During handgripping, heart rate and blood pressure curves were similar in both groups. In patients with this CLS pacemaker, rapid preload reduction during head-up tilting caused an overshooting sensor rate increase, reproducing the authors' clinical observation of postural pacemaker tachycardia in some patients. Consequently, they concluded that the rate response of the CLS pacing system can be inappropriately influenced by rapid shifts of blood volume, affecting right ventricular filling.
Collapse
Affiliation(s)
- Thomas A Cron
- Divisions of Cardiology Psychosomatic Medicine, University Hospital, Basel, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Abstract
Pacing is a field of rapid clinical progress and technologic advances. Clinical progress in the 1990s included the refinement of indications for pacing as well as the use of pacemakers for new, nonbradycardiac indications, such as the treatment of cardiomyopathies and CHF and the prevention of atrial fibrillation. Important published data and studies in progress are shedding new light on issues of pacing mode selection, and they may influence future practice significantly. Important technologic advances include development of new rate-adaptive sensors and sensor combinations and the evolution of pacemakers into sophisticated diagnostic devices with the capability to store data and ECGs. Automatic algorithms monitor the patient for appropriate capture, sensing, battery status, and lead impedance, providing better patient safety and pacemaker longevity.
Collapse
Affiliation(s)
- M Glikson
- Pacemaker Service, Heart Institute, Chaim Sheba Medical Center, Tel Hashomer, Israel
| | | |
Collapse
|
7
|
Abstract
This article reviews the recent major developments in the field of rate adaptive pacing. Including, the improved instrumentation of existing sensors, the use of multiple sensors to enhance sensor specificity or sensitivity, and the automation of sensor calibration. The physiologic benefits and programming of rate adaptive pacing are reviewed.
Collapse
Affiliation(s)
- S K Leung
- Department of Medicine, Kwong Wah Hospital
| | | |
Collapse
|
8
|
Mitrani RD, Simmons JD, Interian A, Castellanos A, Myerburg RJ. Cardiac pacemakers: current and future status. Curr Probl Cardiol 1999; 24:341-420. [PMID: 10388947 DOI: 10.1016/s0146-2806(99)90002-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
9
|
Di Gregorio F, Morra A, Finesso M, Bongiorni MG. Transvalvular impedance (TVI) recording under electrical and pharmocological cardiac stimulation. Pacing Clin Electrophysiol 1996; 19:1689-93. [PMID: 8945025 DOI: 10.1111/j.1540-8159.1996.tb03207.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The cardiac electric impedance was recorded between right atrium and ventricle, throughout the cardiac cycle, by means of a tripolar single pass lead for VDD pacing. The transvalvular impedance signal (TVI) is a sharp periodic wave, with high signal-to-noise ratio, that is detected exclusively in the presence of cardiac mechanical activity. The minimum TVI value is attained during the atrial systole, the maximum at the end of ventricular systole. Different parameters of TVI waveform are affected by changes in the inotropic state, and could therefore be proposed as potential signals for new rate responsive algorithms based on the correlation between inotropic and chronotropic regulation. The signal might be used, moreover, for pacing and sensing validation in autoregulating pacemakers and for fibrillation recognition in ICDs.
Collapse
|
10
|
Abstract
Total artificial hearts (TAHs) and biventricular assist devices (BVADs) have varying levels of acceptance and reliability, and the research on both focuses on their control mechanisms. Efforts generally aim to achieve a response to physiologic demand and left/right output balance, and beneficial cardiac output (CO) and effective control mechanisms have been achieved by eliciting a Starting-like response to preload and afterload. Such control mechanisms, however, generally base device output on a single parameter, such as the preload on the heart. Current TAHs and BVADs provide relatively fixed oxygen delivery to patients with large physiologically induced variations in oxygen consumption. This paper aims to document fluctuations in oxygen consumption that are normal in BVAD and TAH patients, identify a number of patient-generated signals that reflect these fluctuations, and describe a multitiered control algorithm based upon these signals. Such a control system may offer better response times and more physiologic cardiac outputs. There currently exists a microprocessor-based control mechanism that can be adapted to control TAHs and BVADs using input from a variety of sensors, and it can be found in modern implantable pulse generators (IPGs). Today's pacemakers are capable of rate control and can run diagnostic programs and store data that could be valuable in the evaluation of the patient's condition.
Collapse
Affiliation(s)
- A W Hall
- Brady Research, Medtronic Inc., Fridley, Minnesota 55432, USA
| | | | | |
Collapse
|
11
|
Steinhaus DM, Lemery R, Bresnahan DR, Handlin L, Bennett T, Moore A, Cardinal D, Foley L, Levine R. Initial experience with an implantable hemodynamic monitor. Circulation 1996; 93:745-52. [PMID: 8641004 DOI: 10.1161/01.cir.93.4.745] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Measurement of intracardiac hemodynamic parameters has been limited to brief periods in the acute care setting. We developed and evaluated an implantable hemodynamic monitor that is capable of measuring chronic right ventricular oxygen saturation and pulmonary artery pressure. METHODS AND RESULTS The device consists of an electronic controller placed subcutaneously and two transvenous leads placed in the right ventricle (reflectance oximeter) and pulmonary artery (variable capacitance pressure sensor). Implantation was performed in 10 patients with severe left ventricular dysfunction. Average implant pulmonary artery pressures were systolic, 52 +/- 16 mm Hg; diastolic, 29 +/- 11 mm Hg; and mean, 40 +/- 12 mm Hg. The mean right ventricular oxygen saturation at implant was 51%. Provocative maneuvers, including postural changes, sublingual nitroglycerin, and bicycle exercise, demonstrated expected changes in measured oxygen saturation and pulmonary artery pressures over time. At follow-up of 0.5 to 15.5 months, there were no significant differences between pulmonary artery pressures or oxygen saturation values transmitted from the device and simultaneous measurement with balloon flotation catheters. Four of the pulmonary artery leads dislodged and three demonstrated sensor drift, whereas two of the oxygen saturation sensors failed. Four patients died and four received transplants. Pathological study did not demonstrate injury to the right ventricular outflow tract or pulmonic valve. CONCLUSIONS Chronic measurement of hemodynamic parameters in the outpatient setting with implantable sensor technology appears to be feasible. The devices are well tolerated without significant untoward effects, and the sensors generally function well over time, providing reliable information. Clinical usefulness remains to be established.
Collapse
Affiliation(s)
- D M Steinhaus
- Department of Cardiology, University of Missouri-Kansas City School of Medicine, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Candinas R, Mayer IV, Heywood JT, Hu Z, Hess OM. Influence of exercise induced myocardial ischemia on right ventricular dP/dt: potential implications for rate responsive pacing. Pacing Clin Electrophysiol 1995; 18:2121-7. [PMID: 8771122 DOI: 10.1111/j.1540-8159.1995.tb04636.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Right ventricular (RV) dP/dtmax has been used as a simple parameter for rate responsive pacing to simulate the normal sinus node function. However, the effect of acute myocardial ischemia on RV dP/dtmax has not yet been evaluated. METHODS RV high fidelity pressure was measured in 21 patients at rest and during supine bicycle exercise. Nine patients (Group 1 = controls) had no or only minimal alterations of the coronary arteries and 12 (Group 2 = CAD) had significant coronary artery disease with exercise induced left ventricular (LV) wall-motion abnormalities (n = 10) and/or angina pectoris (n = 6). RV pressure and its first derivative (RV dP/dt) were determined by an 8 French micromanometer catheter. The time constant of RV pressure decay (Tau) was calculated from the negative reciprocal of RV pressure versus negative dP/dt during isovolumic relaxation. RV volumes and ejection fraction were calculated from RV biplane angiograms (multiple slice method) at rest and during exercise. RESULTS Heart rate (HR), RV dP/dtmax and dP/dtmin increased significantly during exercise, whereas Tau decreased. There were no significant differences between the two groups, although RV ejection fraction increased from 67% to 72% in the control group but decreased from 63% to 51% in the CAD group (P < 0.05). An exponential relationship was found between HR and dP/dtmax with a correlation coefficient of 0.82 (P < 0.01; SEE = 7% of the mean value). CONCLUSIONS Acute exercise induced myocardial ischemia does not significantly influence RV dP/dtmax during sinus rhythm. Consequently, this index of RV contractility may be used in patients with coronary artery disease as a simple parameter for rate responsive pacing.
Collapse
Affiliation(s)
- R Candinas
- Department of Internal Medicine, University Hospital, Zürich, Switzerland
| | | | | | | | | |
Collapse
|
13
|
Reynolds DW, Bartelt N, Taepke R, Bennett TD. Measurement of pulmonary artery diastolic pressure from the right ventricle. J Am Coll Cardiol 1995; 25:1176-82. [PMID: 7897132 DOI: 10.1016/0735-1097(94)00510-w] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVES This study evaluated the feasibility of estimating pulmonary artery end-diastolic pressure from within the right ventricle. If feasible, this could have important implications for long-term hemodynamic monitoring. BACKGROUND Right ventricular pressure at the time of pulmonary valve opening closely approximates pulmonary artery end-diastolic pressure. Because maximal first derivative of right ventricular pressure (dP/dt) can be easily measured, if it occurs at or very near pulmonary valve opening, right ventricular pressure at maximal right ventricular dP/dt would be an estimation of pulmonary artery end-diastolic pressure. METHODS In 10 patients undergoing routine right and left heart catheterization, simultaneous measurements were made using micromanometers in the right ventricle and pulmonary artery at baseline, during isometric work and Valsalva maneuver. Right ventricular pressure at maximal right ventricular dP/dt was considered the estimated pulmonary artery end-diastolic pressure and was compared with the actual pulmonary artery end-diastolic pressure. RESULTS At baseline, estimated and actual pulmonary artery end-diastolic pressures were (mean +/- SD) 17.7 +/- 6.6 and 16.7 +/- 6.7 mm Hg, respectively (p = NS). During isometric stress, estimated and actual pulmonary artery end-diastolic pressures were 30.4 +/- 12.7 and 28.4 +/- 10.1 mm Hg, respectively (p = NS). During Valsalva maneuvers, estimated and actual pulmonary artery end-diastolic pressures were 36.5 +/- 17.8 and 38.0 +/- 16.1 mm Hg, respectively (p = NS). CONCLUSIONS Although more extensive testing is necessary to evaluate validity in different physiologic and pathologic situations, it appears that right ventricular pressure at maximal right ventricular dP/dt can provide accurate estimation of pulmonary artery end-diastolic pressure.
Collapse
Affiliation(s)
- D W Reynolds
- University of Oklahoma Health Sciences Center, Oklahoma City 73190
| | | | | | | |
Collapse
|
14
|
Kay GN, Philippon F, Bubien RS, Plumb VJ. Rate modulated pacing based on right ventricular dP/dt: quantitative analysis of chronotropic response. Pacing Clin Electrophysiol 1994; 17:1344-54. [PMID: 7971396 DOI: 10.1111/j.1540-8159.1994.tb02454.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Right ventricular contractility increases in response to catecholamine stimulation and greater ventricular preload, factors that increase with exercise workload. Thus, the maximum systolic dP/dt may be a potentially useful sensor to control the pacing rate of a permanent pacing system. The present study was designed to test the long-term performance of a permanent pacemaker that modulates pacing rate based on right ventricular dP/dt and to quantitatively analyze the chronotropic response characteristics of this sensor in a group of patients with widely varying structural heart diseases and degrees of hemodynamic impairment. A permanent pacing system incorporating a high fidelity pressure sensor in the lead for measurement of right ventricular dP/dt was implanted in 13 patients with atrial arrhythmias and AV block, including individuals with coronary artery disease, hypertension, severe obstructive pulmonary disease with prior pneumonectomy, atrial septal defect, dilated cardiomyopathy, restrictive cardiomyopathy, and mitral stenosis. Patients underwent paired treadmill exercise testing in the VVI and VVIR pacing modes with measurement of expired gas exchange and quantitative analysis of chronotropic response using the concept of metabolic reserve. The peak right ventricular dP/dt ranged from 238-891 mmHg/sec with a pulse pressure that ranged from 19-41 mmHg. There was a positive correlation between the right ventricular dP/dt and pulse pressure (r = 0.70, P = 0.012). The maximum pacing rate and VO2max were 72 +/- 6 beats/min and 12.61 +/- 4.0 cc O2/kg per minute during VVI pacing and increased to 124 +/- 18 beats/min and 15.89 +/- 5.9 cc O2/kg per minute in the VVIR pacing mode (P < 0.0003 and P < 0.002, respectively). The integrated area under the normalized rate response curve was 96.7 +/- 45.7% of expected during exercise and 100.1 +/- 43.4% of expected during recovery. One patient demonstrated an anomalous increase in pacing rate in response to a change in posture to the left lateral decubitus position. Thus, the peak positive right ventricular dP/dt is an effective rate control parameter for permanent pacing systems. The chronotropic response was proportional to metabolic workload during treadmill exercise in this study population with widely varying forms of structural heart disease.
Collapse
Affiliation(s)
- G N Kay
- Department of Medicine, University of Alabama at Birmingham 35294
| | | | | | | |
Collapse
|
15
|
Abstract
Many types of sensors have been developed and applied clinically during recent years. Technical improvements can be achieved through greater sensitivity and especially through more specificity for various physical or preferably physiologic signals. However, to date no single sensor properly reflects metabolic demands under all circumstances. In a manner analogous to the normal sinus node, the input from different sources will have to be considered. This leads to the development of dual-sensor or eventually multisensor pacemakers in which the rate is a computed result of blended and cross-checked information on the various parameters that are analyzed.
Collapse
Affiliation(s)
- L J Kappenberger
- Division of Cardiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| |
Collapse
|
16
|
Abstract
Implantable sensors play an important role in physiological cardiac pacing. Sensors can be classified according to the technical methods in which sensing is achieved: the sensing of the evoked ventricular response, intrathoracic impedance and body acceleration forces, and the incorporation of special sensors on pacing electrodes. These sensors differ in their relative merits in terms of speed, proportionality, sensitivity, and specificity of rate response. The efficacy of a sensor can be significantly modified by the algorithm used in relating sensor signal to a pacing rate change. The currently available types of sensors and algorithms are summarized and compared in this review article. The relative merits of these sensors and algorithms form the basis for designing a multisensor pacing system.
Collapse
Affiliation(s)
- C P Lau
- Department of Medicine, University of Hong Kong, Queen Mary Hospital
| |
Collapse
|