Yoked catheter positioning in transseptal endocardial left ventricular lead placement

Background: Transseptal (TS) endocardial left ventricular (LV) lead placement may be needed for cardiac resynchronization therapy, and often requires crossing a preformed puncture in the interatrial septum (IAS) with a lead delivery catheter inserted from an upper body vein (UBV), which can be difficult or impossible to achieve by manipulation from its hub. Consequently, yoked superior approach TS catheterization was developed. Methods: A loop snare housed in a deflectable delivery catheter inserted from an UBV captured the guide wire extending out of a TS sheath inserted from the right femoral vein into the inferior vena cava (IVC). After the IAS had been punctured, the guide wire was left in the left atrium (LA) and the TS sheath withdrawn into the IVC. The delivery catheter was advanced over the snare onto the guide wire, and then pushed by the TS sheath across the IAS puncture into the LA. The snare released the guide wire and was withdrawn. The delivery catheter was manipulated to point toward the LV for lead deployment. If that was not possible, the IAS puncture was dilated with an electrophysiology (EP) catheter housed in a second TS sheath alongside the first one. The EP catheter was captured by the snare and manipulated across the IAS puncture into the LV. The delivery catheter was advanced over the EP catheter directly into the LV. Results: The technique was tried in four patients with challenging anatomy and allowed successful endocardial LV lead placement in all. Conclusions: Yoked catheter positioning facilitates TS endocardial LV lead placement. (PACE 2011; 34:884–893)     

Development of an electrophysiology (EP)-enabled intracardiac ultrasound catheter integrated with NavX 3-dimensional electrofield mapping for guiding cardiac EP interventions: experimental studies.

OBJECTIVE: We have developed an integrated high-resolution intracardiac echocardiography (ICE) catheter for electrophysiology (EP) testing, which can be coregistered in 3-dimensional space with EP testing and ablation catheters using electrofield sensing. METHODS: Twelve open-chest pigs (34-55 kg) and 3 closed-chest pigs were studied. After introduction from the jugular or femoral venous locations, the 9F side-looking, highly steerable (0 degrees -180 degrees), 64-element array catheters could be manipulated easily throughout the right side of the heart. Multisite cardiac pacing was performed for assessing left ventricular (LV) synchrony using tissue Doppler methods. Also, in the open-chest pigs, right atrial (RA) and right ventricular (RV) ablations were performed with a separate radio frequency catheter under fluoroscopic guidance and visualized with ICE to characterize the changes. In the 3 closed-chest pigs, electrofield NavX 3-dimensional coregistration (St Jude Medical Corp, Minneapolis, MN) allowed us to test whether this additional feature could shorten the time necessary to perform 4 targeted ablations in each animal while imaging the ablation catheter and the adjacent region by ICE. RESULTS: Intracardiac anatomy, tricuspid, aortic, pulmonary, and mitral valve function, and pulmonary vein flow were all imaged reproducibly from scanning locations in the RA or RV in all animals, along with assessment of cardiac motion and the effects of multisite pacing. Three-dimensional electrofield displays detailed the spatial relationship between the ICE catheter and ablation catheters such that the time to visualize and ablate 4 sites in each of the 3 closed-chest animals was reduced. CONCLUSIONS: This new technology is a first step in the integration of ICE with EP procedures.     

Thermodilution cardiac output values obtained by using a centrally placed introducer sheath and right atrial port of a pulmonary artery catheter

Thermodilution cardiac output measurements obtained using a centrally placed introducer sheath were compared with thermodilution cardiac outputs obtained using the right atrial port of a balloon-tip, flow-directed pulmonary artery catheter in 15 patients with cardiac failure. Cardiac output values were obtained by manually injecting 10 ml of iced, D5W alternately through the introducer sheath and the right atrial port of the flow-directed catheter. Thirty cardiac output readings were obtained in the 15 patients. Cardiac outputs obtained using the right atrial port (CORA) did not differ significantly from cardiac outputs obtained using the introducer sheath (COSP) (5.3 +/- 0.2 vs. 5.2 +/- 0.2 L/min). The correlation between CORA and COSP was significant (r = .94, p less than .0001) and could be described by the formula CORA = 0.33 + 0.96 COSP. We conclude that when the right atrial port of a flow-directed catheter is nonfunctional, a thermodilution cardiac output obtained using a centrally placed introducer sheath offers a reliable alternative.     

Transcardiac conductance for continuous measurement of left ventricular volume: validation vs. angiography in patients

Objective To test the feasibility of the transcardiac conductance (TCC) method for continuous, on-line measurement of absolute left ventricular (LV) volume and to validate the method by comparison with biplane angiography.Design and setting Prospective clinical feasibility and validation study in a cardiac catheterization laboratory in a university hospital.Patients and interventions Ten patients scheduled for electrophysiological studies (n=5), percutaneous transluminal coronary angioplasty (n=3), and left- and right-sided cardiac catheterization (n=2) were enrolled in the feasibility study. Twenty patients scheduled for diagnostic left- and right-sided cardiac catheterization were included in the validation study. The latter were studied at baseline and during right atrial pacing 30 beats/min above baseline.Measurements and results In the feasibility study satisfactory ventricular volume signals were obtained by TCC in eight of ten patients. In the validation study calibration factors ( and V^p) for TCC were obtained by thermodilution and hypertonic saline dilution, to yield absolute LV volume. Results indicate a good linear correlation with angiographic volume (R²=0.78) with an intercept of 10±15 ml, not significantly different from 0 and slope of 1.17±0.16. Mean calibration factors and V^p were 0.017±0.002 (interpatient variability 0.018) and 75.1±0.4 ml (interpatient variability 35.4 ml), respectively.Conclusions The TCC method provides on-line and continuous LV volume signals in patients in a relatively noninvasive way. Calibration yields absolute LV volumes with a good linear correlation in comparison to biplane LV angiography. TCC appears to be a promising methodology for monitoring absolute LV volume in the ICU.This research was supported by a grant from The Netherlands Heart Foundation (NHS 98-151); J.W.J. is an established clinical investigator of The Netherlands Heart Foundation (2001-D032)     

Beat to beat 3-dimensional intracardiac echocardiography: theoretical approach and practical experiences

Three-dimensional (3D)-imaging provides important information on cardiac anatomy during electrophysiological procedures. Real-time updates of modalities with high soft-tissue contrast are particularly advantageous during cardiac procedures. Therefore, a beat to beat 3D visualization of cardiac anatomy by intracardiac echocardiography (ICE) was developed and tested in phantoms and animals. An electronic phased-array 5–10 MHz ICE-catheter (Acuson, AcuNav?/Siemens Medical Solutions USA/64 elements) providing a 90° sector image was used for ICE-imaging. A custom-made mechanical prototype controlled by a servo motor allowed automatic rotation of the ICE-catheter around its longitudinal axis. During a single heartbeat, the ICE-catheter was rotated and 2D-images were acquired. Reconstruction into a 3D volume and rendering by a prototype software was performed beat to beat. After experimental validation using a rigid phantom, the system was tested in an animal study and afterwards, for quantitative validation, in a dynamic phantom. Acquisition of beat to beat 3D-reconstruction was technically feasible. However, twisting of the ICE-catheter shaft due to friction and torsion was found and rotation was hampered. Also, depiction of catheters was not always ensured in case of parallel alignment. Using a curved sheath for depiction of cardiac anatomy there was no congruent depiction of shape and dimension of static and moving objects. Beat to beat 3D-ICE-imaging is feasible. However, shape and dimension of static and moving objects cannot always be displayed with necessary steadiness as needed in the clinical setting. As catheter depiction is also limited, clinical use seems impossible.     

彩色多普勒超声心动图、Swan-Ganz导管和脉波指示剂连续心排血量监测仪血流动力学检测的同步比较研究

目的对比研究彩色多普勒超声心动图(CDE)、Swan-Ganz导管和脉波指示剂连续心排血量(PiCCO)监测仪在血流动力学检测中的相关性。方法选取2006年3月至2008年10月入苏州市立医院东区ICU的心功能不全的危重病患者共8例,男5例,女3例,平均(51.4±21.1)岁。记录患者一般情况,并置入PiCCO导管和Swan-Ganz导管,通过CDE、Swan-Ganz导管法和PiCCO导管法同步测量每搏输出量(SV)和每分输出量(CO),比较三种方法所测数据的相关性。结果运用CDE、Swan-Ganz导管法和PiCCO导管法测量所得的SV依次为(62.4±29.3)ml、(53.1±14.0)ml和(49.9±14.7)ml。组间差异无统计学意义(P均0.05),组间均具有相关性,相关系数值分别为0.78、0.91和0.76;测量所得的CO分别为(5.9±2.2)L/min、(5.1±1.4)L/min和(5.0±1.4)L/min。组间差异无统计学意义(P均0.05),组间均具有相关性,相关系数值值分别为0.75、0.96和0.72。结论 CDE、Swan-Ganz导管和PiCCO监测仪检测的SV、CO具有相关性。     

Use of preshaped sheath to plan and facilitate cannulation of the coronary sinus for the implantation of cardiac resynchronization therapy devices: preshaped sheath for implantation of biventricular devices

OBJECTIVES: The aim of the study is to describe a new technique for facilitating the implantation of cardiac resynchronization therapy (CRT) devices. BACKGROUND: CRT, by simultaneous pacing of the right and left ventricles has proven to be a useful treatment for patients with advanced heart failure and left ventricular (LV) systolic dysfunction, who have concomitant LV dyssynchrony. One of the greatest challenges to the wide applications of this therapy has been the technical difficulty encountered with implantation of the left ventricular lead. This is mainly due to the varied anatomy of the coronary venous system, which is further complicated by distortion of the anatomy in patients with advanced heart failure. METHODS: Details of the coronary venous anatomy are initially assessed by cannulating the coronary sinus (CS) using a specialized long preshaped sheath introduced from the femoral approach. Occlusive venography is performed in three views, and then the guide wire or the deflated balloon catheter is left in the CS for guidance. The most suitable equipment for the anatomy is chosen. Then, the operative site is prepped and the CS is approached from above. RESULTS: From November 2003 until December 2004, we have used this approach on all patients presenting for CRT device implantation at Prince Sultan Cardiac Center (n = 25). The CS was cannulated using the preshaped catheter in less than 5 minutes in all cases. After delineation of the anatomy, successful CRT implantation was achieved in all patients. Mean procedure time for the implantation was 110 +/- 18 minutes. Uncomplicated minor CS dissection related to the use of the preshaped sheath was observed in 1 patient without consequences. CONCLUSIONS: The use of preshaped sheath from the femoral approach facilitates planning the successful and safe implantation of CRT systems.     

Right ventricular volume measurement: can conductance do it better?

The measurement of right ventricular volume will be reviewed with special reference to the conductance catheter technique. The historical development of the intracavitary impedance technique will be described along with the theory of the multielectrode conductance method. The major potential advantage of this technique is its ability to measure dynamic volume change during the cardiac cycle. This enables a real time beat to beat assessment of ventricular volume in addition to providing continuous recordings during loading manoeuvres performed on the ventricle. However, the conductance catheter technique is based on the assumption that the electric field produced by the catheter is homogeneous and parallel to the long axis of the ventricle, and the current, created by the excitation electrodes of the catheter, is contained within the ventricular cavity. The measurement of these two calibration factors (known as parallel conductance volume (V(C)) and dimensionless slope factor (alpha)), along with the effects of changes in blood resistivity and the orientation of the catheter on the measurement of absolute volume, will be described. Furthermore, some of the clinical applications of the technique in adults and children with heart disease will be outlined.     

Effects of proximal ventricular septal pacing on hemodynamics and ventricular activation

Recently the use of alternate site pacing to improve cardiac function in patients with bradyarrhythmias has increased. In the present study, hemodynamics of right ventricular septal pacing were studied in seven dogs. A bipolar screw-in lead and endocardial lead were placed in the proximal right ventricular septum and right ventricular apex, respectively. The right ventricle was paced from each site. A conductance catheter and Millar catheter were inserted into the left ventricle to determine the left ventricular pressure and the pressure-volume loop. Cardiac output was measured using the thermodilution method. In five of the seven dogs, ventricular activation was documented by isochronal epicardial activation mapping during each pacing mode. Mean arterial pressure and cardiac output during septal pacing were significantly higher than during apical pacing (110 +/- 17 mmHg vs 100 +/- 18 mmHg; 1.00 +/- 0.39 L/min vs 0.89 +/- 0.33 L/min). The positive dp/dt during septal pacing was significantly higher than during apical pacing (2137 +/- 535 mmHg/s vs 1911 +/- 404 mmHg/s). End-systolic elastance during septal pacing was significantly higher compared to apical pacing (13.1 +/- 0.3 mmHg/mL vs 8.9 +/- 4.0 mmHg/mL). The ventricular activation time during septal pacing was significantly shorter than during apical pacing. The epicardial maps generated during septal pacing were similar to those from atrial pacing. We conclude that hemodynamics and interventricular conduction are less disturbed by proximal right ventricular septal pacing than apical pacing in dogs with normal hearts.     

Variability of splanchnic blood flow in patients with sepsis

OBJECTIVES: Previous studies on therapeutic interventions in sepsis have assumed stability of the measure of splanchnic blood flow throughout the study. We assessed the variability of splanchnic blood flow during stable global hemodynamics in eight patients with sepsis requiring treatment with dobutamine and/or norepinephrine. DESIGN AND SETTING: Prospective clinical study in an intensive care unit of a university hospital. MEASUREMENTS AND RESULTS: Global and regional hemodynamics were measured at baseline, 2 h later, and 4 h later. Cardiac output was measured by transpulmonary thermodilution, intrathoracic blood volume as an indicator of cardiac preload, and total blood volume by the double indicator (thermo-dye) dilution technique. Total body oxygen consumption was assessed by indirect calorimetry using a metabolic cart. Splanchnic blood flow was measured by the continuous indocyanine green method, and gastric mucosal CO2 tension by gas tonometry. Neither absolute nor fractional splanchnic blood flow (as ratio of cardiac output) revealed significant global tendencies during the study period. However, variance component analysis showed that splanchnic blood flow determinations varied considerably within patients, for repeated measurements at 5-min intervals (standard error 31.1%) as well as for average values at 2-h intervals (25.6%). CONCLUSION: Stable global hemodynamics during a 4-h period in septic patients does not exclude marked changes in splanchnic blood measured by a hepatic venous catheter technique.     

Noninvasive measurement of cardiac output by continuous-wave Doppler echocardiography: initial experience and review of the literature

Doppler echocardiographic measurement of the velocity of blood flow in the ascending aorta is a noninvasive method for determining cardiac output in the critically ill patient. Fifty-four patients in the medical intensive care unit (35 men and 19 women, age range 41 to 91 years) in whom a Swan-Ganz catheter had been inserted underwent measurement of cardiac output with use of a commercially available continuous-wave Doppler echocardiographic instrument. The aortic root diameter was measured by A-mode echocardiography. An additional 26 patients (17 men and 9 women, age range 20 to 83 years) who had undergone an open-heart surgical procedure and had hemodynamic monitoring in the postoperative period also underwent Doppler measurement of cardiac output. In these patients, the aortic root diameter was measured directly intraoperatively. Cardiac output was also determined by thermodilution in both groups. An adequate A-mode study was possible in 83% of the medical patients but only 27% of the surgical patients. Doppler signals were adequate in 84% of the medical patients and 92% of the surgical patients. The correlation between thermodilution and Doppler-derived cardiac output was good in both the medical (r = 0.94, SEE = 0.78, P less than 0.001) and the surgical (r = 0.85, SEE = 0.78, P less than 0.001) group. Doppler echocardiography is a promising noninvasive method for determining cardiac output in critically ill patients.     

Detecting Right Ventricular Volume Changes Using the Conductance Catheter

The purpose of this study was to assess the role of conductance catheter position within the right ventricle in obtaining adequate indications of phasic changes in ventricular volume. Possible applications of this technology are in rate responsive pacemakers and implantable defibrilators. The conductance catheter was placed in the right ventricle by cannulation of a jugular or femoral vein or a branch of the pulmonary artery. Position within the ventricle was documented from biplane fluoroscopy. Stroke volume was perturbed by: bolus injection of blood, vagal stimulation, venous infusion of methylcholine chloride, or isoprenaline. Four criteria were used to assess the quality of volume signals: (1) volume signal phase relative to the electrocardiogram; (2) magnitude parity of volume change from each electrode pair; (3) freedom from artifact; and (4) indication of stroke volume change during interventions. Greyhound dogs of either sex (n = 33), weight 20-32 kg. A total of 236 recordings from 14 distinct catheter positions were analyzed. Catheter positions originating from a femoral cannulation and one position from the pulmonary artery gave markedly superior volume transduction compared to those from the jugular route. Although right ventricular volume transduction was possible from all catheter trajectories, those resulting from the femoral approach were clearly superior. In the right ventricle, the inability to transduce a sufficient proportion of ventricular volume, in concert with the potential sensitivity of the catheter to atrial volume changes, may seriously limit the potential of the conductance technique in the applications envisaged.     

Validation of a volumic reconstruction in 4-d echocardiography and gated SPECT using a dynamic cardiac phantom

A dynamic cardiac phantom was used as a reference to compare the volumes reconstructed with 4-D echocardiography and gated single-photon emission computed tomography (SPECT). 4-D echocardiography used a new prototype of rotating scan head to acquire ultrasound (US) images during a cardiac cycle, associated with a new protocol (left ventricular 4-D or LV 4-D) to reconstruct the volume deformations of the heart as a function of time. Gated SPECT data were acquired with a standard single-head gamma camera, and the reconstructions were carried out using the Mirage software released by Segami. The influences of different LV 4-D parameters were tested and analyzed. End-diastolic volume, end-systolic volume, and ejection fraction were measured using both LV 4-D and gated SPECT. Results obtained showed a straight correlation between the two examinations. The agreement confirmed the relevance of the comparisons. This study is an initial step before conducting clinical trials to exhaustively compare the two modalities.     

The effect of lung inflation on absolute ventricular volume measurement by conductance

BACKGROUND: Conductance catheter in vivo ventricular volume measurements during lung ventilation may provide important information on left ventricular (LV) function. Breathing potentially may alter parallel conductance (V(c)), complicating interpretation of the conductance-derived volume signals. The effects of controlled positive pressure lung inflation (PPLI) on measured parallel conductance with dual-field conductance volumetry were investigated. METHODS: Eight anaesthetized pigs were instrumented with an LV dual-field conductance volumetry catheter. V(c) was measured repeatedly, using the hypertonic saline injection method, at three different levels of lung insufflation: continuous positive airway pressure (PPLI) 0, 5, and 10 cm H(2)O. RESULTS: V(c)s measured at PPLI 0, 5 and 10 cm H(2)O were 70.9 +/- 4.8, 70.7 +/- 5.5 and 70.5 +/- 5.9 ml, respectively. The corresponding uncalibrated end-diastolic volumes (EDV(u)) were 115.5 +/- 7.1, 117.0 +/- 7.5 and 117.5 +/- 7.7 ml, respectively. Mean coefficients of variance for V(c) and EDV(u) at all three PPLI levels were 3.8% and 1.25%, respectively. DISCUSSION: Several levels of PPLI demonstrated no systematic change in parallel conductance for LV dual-field conductance volume signal. We concluded that lung inflation at these levels does not generate changes in V(c).     

Intracardiac echocardiography (9 MHz) in humans: methods, imaging views and clinical utility

A new low-frequency (9 MHz, 9 Fr) catheter-based ultrasound (US) transducer has been designed that allows greater depth of cardiac imaging. To demonstrate the imaging capability and clinical utility, intracardiac echocardiography (ICE) using this lower frequency catheter was performed in 56 patients undergoing invasive electrophysiological procedures. Cardiac imaging and monitoring were performed with the catheter transducer placed in the superior vena cava (SVC), right atrium (RA) and/or right ventricle (RV). In all patients, ICE identified distinct endocardial structures with excellent resolution and detail, including the crista terminalis, RA appendage, caval and coronary sinus orifices, fossa ovalis, pulmonary vein orifices, ascending aorta and its root, pulmonary artery, RV and all cardiac valves. The left atrium and ventricle were imaged with the transducer at the limbus fossa ovalis of the interatrial septum and in the RV, respectively. ICE was important in identifying known or unanticipated aberrant anatomy in 11 patients (variant Eustachian valve, atrial septal aneurysm and defect, lipomatous hypertrophy, Ebstein's anomaly, ventricular septal defect, tetralogy of Fallot, transposition of the great arteries, disrupted chordae tendinae and pericardial effusion) or in detecting procedure-related abnormalities (narrowing of SVC-RA junction orifice or pulmonary venous lumen, atrial thrombus, interatrial communication). In patients with inappropriate sinus tachycardia, ICE was the primary ablation catheter-guidance technique for sinus node modification. With ICE monitoring, the evolution of lesion morphology with the three imaging features including swelling, dimpling and crater formation was observed. In all patients, ICE was contributory to the mapping and ablation process by guiding catheters to anatomically distinct sites and/or assessing stability of the electrode-endocardial contact. ICE was also used to successfully guide atrial septal puncture (n = 9) or RA basket catheter placement (n = 4). Thus, ICE with a new 9-MHz catheter-based transducer has better imaging capability with a greater depth. Normal and abnormal cardiac anatomy can be readily identified. ICE proved useful during electrophysiological mapping and ablation procedures for guiding interatrial septal puncture, assessing placement and contact of mapping and ablation catheters, monitoring ablation lesion morphological changes, and instantly diagnosing cardiac complications.     

Full-motion two- and three-dimensional pulmonary vein imaging by intracardiac echocardiography after pulmonary vein isolation

Background: The pulmonary veins (PVs) are topographically complex and motile, so angiographic visualization of the PVs anatomy is limited. An imaging technique that accurately portrays the pulmonary vein ( PV) anatomy would be valuable during and after catheter ablation procedures.
Purpose: We investigated whether three-dimensional (3D) intracardiac echocardiography (ICE) can visualize radiofrequency (RF)-induced tissue changes after PV isolation.
Methods: We performed 3D ICE studies with a 9F, 9-MHz ICE catheter after segmental or extended PV isolation. The ICE catheter was placed 3–4 cm inside the PV ostium and mounted onto a pullback device. Sequential two-dimensional (2D) images of the full length of the vein were obtained in 0.3 mm steps with cardiac and respiratory cycle gating. Each image was fed into a computer, and the aggregate data set was reconstructed into a 3D, full-motion image. RF lesion location and lesion size were studied on 67 pullback images from 29 patients.
Results: The 2D and 3D reconstruction was possible for 27 left superior PVs, 13 left inferior PVs, 26 right superior PVs, and one right inferior PV. The ablation site was identified 3–7 mm inside the PV ostium, and a 1/2 – 4/5 circumferential area was ablated with no clinically relevant stenosis. No significant differences were found on the ablated area or ablation site between segmental and extensive PV isolation.
Conclusion: The 2D and 3D ICE of the PVs provides detailed anatomical information of the proximal PVs, and RF-induced tissue changes in the PV wall can be visualized by ICE.     

心腔内超声评价希氏束起搏心脏血流动力学和解剖结构重构

目的采用单一的心腔内超声心动图和组织多普勒显像技术检测和评价直接希氏束起搏诱导的心室激动顺序、心脏解剖结构和血流动力学重构.方法六只急性闭胸直接希氏束起搏狗模型.采用美国Medtronic导向引导鞘管和主动螺旋电极,在心腔内超声心动图和组织多普勒显像技术引导下将起搏电极分别置放于希氏束(n=6)和右室心尖(n=6).所有部位的起搏频率均控制为120次/min.采用二维灰阶、血流频谱多普勒和组织多普勒技术,分别测量和计算心脏不同部位起搏时心室各房室和相连大血管解剖结构内径和容量、心肌的激动顺序和相关血流动力学参数,并进行不同起搏状态上述测量参数的配对统计比较.结果希氏束起搏状态下,左心室壁内心肌的激动顺序、心脏主要解剖结构和血流动力学参数与窦性心律状态下相同参数比较无显著性差异;与右心室心尖起搏状态下相同参数比较有显著性差异.结论单一的心腔内超声和组织多普勒技术能够有效地量化评价心脏起搏状态下的心脏解剖结构和血流动力学改变.与右心室心尖部起搏相比较,希氏束起搏能够明显地改善心脏解剖和血流动力学重构.     

Real-time three-dimensional intracardiac echocardiography

Using catheter-mounted 2-D array transducers, we have obtained real-time 3-D intracardiac ultrasound (US) images. We have constructed several transducers with 64 channels inside a 12 French catheter lumen operating at 5 MHz. The transducer configuration may be side-scanning or beveled, with respect to the long axis of the catheter lumen. We have also included six electrodes to acquire simultaneous electrocardiograms. Using an open-chest sheep model, we inserted the catheter into the cardiac chambers to study the utility of in vivo intracardiac 3-D scanning. Images obtained include a cardiac four-chamber view, mitral valve, pulmonic valve, tricuspid valve, interatrial septum, interventricular septum and ventricular volumes. We have also imaged two electrophysiological interventional devices in the right atrium, performed an in vitro ablation study, and viewed the pulmonary veins in vitro.     

Evaluation of a new invasive continuous cardiac output monitoring system: the truCCOMS system

Objective To compare measurements of cardiac output using a new pulmonary artery catheter with those obtained using two " gold standard " methods: the periaortic transit time ultrasonic flow probe and the conventional pulmonary artery thermodilution.Design Prospective clinical trial.Setting Cardiac surgery operating room and surgical ICU in a university hospital.Material and methods In the operating room, a new pulmonary artery catheter (truCCOMS system) was inserted in eight patients. A periaortic flow probe was inserted in four of them. Measurements of cardiac output obtained with the truCCOMS catheter and with the flow probe were compared at different phases of the surgical procedure. In the intensive care unit, the cardiac output displayed by the truCCOMS monitor was compared with the value obtained after bolus injection performed subsequently.Results In the operating room (70 measurements), the coefficient of correlation between cardiac output measured by the flow probe and the truCCOMS system was r² = 0.79, the bias was +0.11 l/min with a precision of 0.47 l/min, and limits of agreement –0.83 to +1.05 l/min. In the intensive care unit (108 measurements), the coefficient of correlation between cardiac output measured by thermodilution and the truCCOMS system was r² = 0.56, the bias was –0.07 l/min, the precision was 0.66 l/min, and the limits of agreement were –1.39 to +1.25 l/min.Conclusion The truCCOMS system is a reliable method of continuous cardiac output measurement in cardiac surgery patients.     

Assessment of right atrial (RA) and right ventricular (RV) function by gated blood pool scan with krypton-81m: RA and RV pressure-volume loops with simultaneous pressure data

We developed a new method of analyzing right atrial (RA) and right ventricular (RV) function by Krypton-81m gated blood pool scan (Kr-81m-GBPS). Pressure data were recorded simultaneously with a modified Swan-Ganz catheter. Krypton-81m (Kr-81m) is ideally suited to hemodynamic study of the right heart because of the following characteristics: physical half-life of 13 seconds; high photon yield and gamma ray energy of 190 KeV; low radiation exposure; and deployment during exhalation when the left heart is not active. A computerized method for list mode data acquisition was developed to collect data from the gamma camera, ECG wave, and RA and RV pressure simultaneously. RA and RV volume curves were obtained by calibrating the time-activity curves with end-diastolic volumes and cardiac output. Ejection fraction (EF) was used in the calculation of volume and cardiac output (CO) was measured by the thermodilution method. From RA and RV pressure and volume curves, RA and RV pressure-volume (P-V) loops were created simultaneously and displayed on the same plane. One spanning cardiac cycle of RV beats was separated into four phases: the ventricular emptying phase, the early ventricular filling phase, equilibrium, and the late ventricular filling phase. One spanning cardiac cycle of RA beats also was separated into four phases as follows: the atrial filling phase, the early atrial emptying phase, equilibrium, and the late atrial emptying phase. P-V loops of RA and RV were shifted after sublingual nitroglycerin administration. This new method is potentially useful in the study of right heart hemodynamics.