Measurement Of Left Atrial Pressure Research Articles

The training and learning process of transseptal puncture using a modified technique

As the transseptal (TS) puncture has become an integral part of many types of cardiac interventional procedures, its technique that was initial reported for measurement of left atrial pressure in 1950s, continue to evolve. Our laboratory adopted a modified technique which uses only coronary sinus catheter as the landmark to accomplishing TS punctures under fluoroscopy. The aim of this study is prospectively to evaluate the training and learning process for TS puncture guided by this modified technique. Guided by the training protocol, TS puncture was performed in 120 consecutive patients by three trainees without previous personal experience in TS catheterization and one experienced trainer as a controller. We analysed the following parameters: one puncture success rate, total procedure time, fluoroscopic time, and radiation dose. The learning curve was analysed using curve-fitting methodology. The first attempt at TS crossing was successful in 74 (82%), a second attempt was successful in 11 (12%), and 5 patients failed to puncture the interatrial septal finally. The average starting process time was 4.1 ± 0.8 min, and the estimated mean learning plateau was 1.2 ± 0.2 min. The estimated mean learning rate for process time was 25 ± 3 cases. Important aspects of learning curve can be estimated by fitting inverse curves for TS puncture. The study demonstrated that this technique was a simple, safe, economic, and effective approach for learning of TS puncture. Base on the statistical analysis, approximately 29 TS punctures will be needed for trainee to pass the steepest area of learning curve.

Hemodynamic effect of iatrogenic atrial septal defect after percutaneous mitral valve repair using the MitraClip device

Aim: Percutaneous mitral valve repair (PMVR) using the MitraClip device has become a therapeutic alternative for high surgical risk patients with symptomatic mitral regurgitation. The procedure involves transseptal puncture and results in a new atrial septal defect (ASD) after withdrawal of the 22F MitraClip guiding catheter. The functional effect of the new atrial septal defect is not defined. Methods: In 28 patients with symptomatic mitral regurgitation undergoing PMVR using the MitraClip device, 3D TEE was used to measure by direct en-face imaging the area of the new atrial septal defect, to determine the resulting left-to-right atrial shunt volume and define the left atrial pressure reduction resulting from the new ASD. Analysis of the velocity time integral (VTI) across the septal defect after withdrawal of the guiding catheter allowed calculation of the shunt volume. Diastolic VTI analysis of the mitral flow was performed before and after withdrawal of the MitraClip guiding catheter to determine the change in inflow into the left ventricle. Direct left atrial pressure measurements were obtained before and after withdrawal of the MitraClip guiding catheter. Results: Mitral valve regurgitant volume by color Doppler 3D TEE was determined as the product of vena contracta areas defined by direct planimetry and velocity time integral using continuous-wave Doppler. Regurgitant volume was reduced from 86±31 mL preintervention to 43±22 mL postintervention. The new ASD had an effective area of 0.19 cm2, 44% of the area of the 22F guiding catheter. Considering the VTI across the septal defect of 72±25 cm/sec, the left-to-right atrial shunt volume was calculated to be 13±5 ml per heart beat. The diastolic forward flow across the mitral valve was reduced by 15±11 ml/ heart beat immediately after withdrawal of the MitraClip guiding catheter. Mean left atrial pressure was reduced from 17±8 mmHg with the guiding catheter still in the left atrium to 15±8 mmHg after withdrawal of the guiding catheter. Conclusion: The creation of a new ASD as consequence of the large diameter MitraClip guiding catheter results in volume and pressure relief of the left atrium. This contributes significantly to the hemodynamic changes implemented by the MitraClip procedure.

Transseptal catheterization: technique and complications

Transseptal puncture was first described by Ross and Cope, independently, in 1959. This technique was developed predominantly for the diagnostic evaluation of valvular heart disease. After a few years, transseptal catheterization has been replaced by indirect measurements of left atrial pressure using the Swan-Ganz catheter. Recently, there has been a renewed interest in transseptal puncture because of emerging therapeutic procedures for structural heart disease and atrial fibrillation ablation. Current transseptal technique has changed very little since the initial reports, but new tools are now available to facilitate transseptal puncture including echocardiographic imaging (three-dimensional, transesophageal, or intracardiac), radiofrequency powered wires and needle-tipped guidewires. Transseptal catheterization can be performed with high success rates and low complication rates. An Italian survey reported a success rate of 99% with a complication rate of 0.76%. Complications included aortic perforation, pericardial tamponade, ST-segment elevation, cerebral air embolization, systemic embolization, and thrombus formation on the transseptal sheath.

Hemodynamics in the Cardiac Catheterization Laboratory of the 21st Century

There has been a striking evolution in the role of the cardiac catheterization laboratory over the past decades.1 In the 1950s and 1960s, hemodynamic assessment in the cardiac catheterization laboratory was essential for understanding the physiology and pathophysiology of patients with cardiovascular diseases. With the development of surgical interventions to treat patients with valvular and congenital heart disease, it became necessary for the cardiac catheterization laboratory to provide an accurate hemodynamic assessment, laying out a therapeutic road map. Nearly all patients who had open heart surgery underwent a complete hemodynamic catheterization before surgery. In the 1980s and 1990s, the evolution of 2-dimensional echocardiography and Doppler echocardiography provided an alternative noninvasive approach for the assessment of both cardiac anatomy and hemodynamics in patients with structural heart disease.2 By measuring blood flow velocities noninvasively, Doppler echocardiography was able to provide information on volumetric flow, intracardiac pressures, pressure gradients, and valve areas, as well as diastolic filling of the heart. Furthermore, noninvasive studies could be repeated easily, allowing the practitioner to follow the progress of his/her patient's condition longitudinally. At the same time, there was growing emphasis on coronary angiography for defining epicardial coronary disease with the subsequent development of interventional approaches for coronary disease with catheter-based therapies. As the major focus in the catheterization laboratory shifted to the diagnosis and treatment of the patient with acute and chronic coronary artery disease, the hemodynamic assessment of patients with structural heart disease was left to the noninvasive echocardiographic laboratory. As a consequence, many cardiac catheterization laboratories provided neither the training nor the expertise to assess hemodynamics properly. However, the advent of procedures such as balloon valvotomy, percutaneous valve implantation, and septal ablation has revived interest in structural heart disease and provided the invasive cardiologist with an armamentarium to treat patients who previously …

Serial Doppler Echocardiography and Tissue Doppler Imaging in the Detection of Elevated Directly Measured Left Atrial Pressure in Ambulant Subjects With Chronic Heart Failure

This study sought to determine the accuracy of Doppler echocardiography and tissue Doppler imaging (TDI) measurements in detecting elevated left atrial pressure (LAP) in ambulant subjects with chronic heart failure using directly measured LAP as the reference. Echocardiographic indexes including the ratio of transmitral to annular early diastolic velocities (E/e') may identify raised invasively measured left ventricular filling pressures when tested in cross-sectional studies in some populations. The accuracy of these indexes when measured sequentially remains untested. We determined the accuracy of Doppler echocardiography and TDI measurements in detecting elevated directly measured LAP in ambulant subjects with stable chronic heart failure. Fifteen patients with New York Heart Association functional class II to III heart failure and a permanently implanted direct LAP monitoring device underwent serial echocardiography. Simultaneous resting mean LAP, Doppler mitral inflow, mitral annular TDI, and pulmonary venous inflow velocities were obtained on each occasion. Receiver-operator characteristic curve analysis was used to compare the accuracy of the Doppler variables to detect an elevated device LAP ≥15 and ≥20 mm Hg. The patients (13 men, mean age: 71 years, mean left ventricular ejection fraction: 32 ± 12%) underwent 60 simultaneous echocardiographic studies and LAP measurements with a median of 4 (1 to 7) studies per patient. Mean LAP was 16.9 (range 5 to 39 mm Hg) at echocardiography (n = 60). E/e' had the greatest accuracy for detection of LAP ≥15 mm Hg with an area beneath the receiver-operator characteristic curve >0.9. In comparison, area under the curve for mitral E velocity and mitral E/A were 0.77 and 0.76, respectively (p < 0.008 vs. E/e' medial and average). Single and serial measurements of mitral inflow and mitral annular TDI velocities (E/e') can reliably detect raised directly measured LAP in ambulant subjects with compensated chronic heart failure. (Hemodynamically Guided Home Self-Therapy in Severe Heart Failure Patients [HOMEOSTASIS]; NCT00547729).

Relationship of Pulmonary Artery Wedge Pressure to Left Atrial Pressure and Pulmonary Vascular Resistance in Preoperative Fontan Patients

Pulmonary artery wedge pressure (PAWp) as a surrogate for left atrial pressure (LAp) has been validated in patients with fully pulsatile two-ventricle circulations. This study was to validate PAWp as an accurate estimate of LAp for calculating pulmonary vascular resistance in single-ventricle patients after the bidirectional Glenn operation. A prospective study measuring direct branch pulmonary artery pressures, ipsilateral PAWp, and direct LAp to calculate pulmonary and systemic blood flows was conducted. Pulmonary vascular resistance (PVR) was calculated for each patient using the PAWp and compared to the PVR calculated by direct LAp measurements. Twenty-eight patients were enrolled; 27 were eligible for study inclusion. Ages ranged from 21 to 60 months and weights ranged from 9.5 to 20.8 kg. Underlying congenital heart defect diagnoses varied, with all patients either functionally or anatomically univentricular. Left mPAWp measured 4.4 ± 2.6, statistically different from simultaneous direct mLAp of 2.5 ± 2.4 mmHg (P < 0.001. Right mPAWp measured 4.3 ± 3.2 mmHg, statistically different from simultaneous direct mLAp of 2.8 ± 2.6 mmHg (P < 0.001. The PVR calculated using mPAWp was 1.2 ± 0.7 W.U., statistically different to 1.8 ± 0.95 W.U. using mLAp (P < 0.001). The average PVR measurement calculated using mPAWp underestimated the PVR calculated using mLAp by 0.6 W.U. It can be extrapolated that a PVR of 2.3 W.U. calculated using wedge measurements would estimate a PVR of 3 W.U. calculated using direct LA measurements. In this study, the PVR calculated using PAWp as a surrogate for LAp either equaled or underestimated the true PVR, up to 33% different. This difference is important in patients with univentricular physiology who rely on low PVR for cardiac output. Thus, based on this study, a PVR measurement of greater than 2.3 W.U. by the mPAWp method should prompt a direct LA pressure measurement, in order to more appropriately determine true surgical risk.

Stiff left atrial syndrome after catheter ablation for atrial fibrillation: Clinical characterization, prevalence, and predictors

There have been no studies of atrial diastolic function after catheter ablation of atrial fibrillation (AF). We encountered a few patients with symptomatic left atrial (LA) diastolic dysfunction and associated pulmonary hypertension (PH) that developed after catheter ablation for atrial fibrillation. Similar findings were described in patients after cardiac surgery and were referred to as the "stiff left atrial syndrome." The purpose of this study was to prospectively quantify the incidence of patients developing PH associated with diastolic hemodynamic abnormalities of the LA after radiofrequency ablation of AF and to identify the possible predictors. Between January 2009 and July 2010, data on 1,380 consecutive patients were prospectively collected. Before ablation and at follow-up, all patients had an echocardiogram to assess for the presence of PH. Patients with no echocardiographic evidence of PH but complaining of unexplained dyspnea with LA diastolic abnormalities were evaluated with right heart catheterization (RHC). Patients were included in the analysis if they developed new or worsening PH postablation with evidence of LA diastolic dysfunction by RHC or direct LA pressure measurement. All patients were evaluated for pulmonary vein stenosis and excluded if this condition was identified. The mean age was 62 ± 11 (75% male), and nonparoxysmal AF was the predominant arrhythmia (71%). New or worsening PH with associated LA diastolic abnormalities was detected in 19 (1.4%) patients after ablation. The prevalence of PH did not differ between AF types (P = .612). Compared with patients who did not develop PH, LA scarring (P <.001), diabetes (P = .026), and obstructive sleep apnea (OSA; P = .006) were more frequently observed among those who developed PH. In a multivariable logistic model, preprocedure LA size ≤45 mm (odds ratio [OR] = 6.13; P = .033), mean LA pressure (OR 1.14; P = .025), severe LA scarring (OR = 4.4; P = .046), diabetes mellitus (OR = 9.5; P = .004), and OSA (OR = 6.2; P = .009) were independently associated with the development of PH postablation. After radiofrequency catheter ablation of atrial fibrillation (RFCAF), PH with LA diastolic dysfunction or the so-called stiff LA syndrome is a rare but potentially significant complication of AF ablation. Severe LA scarring, LA ≤45 mm, diabetes mellitus, OSA, and high LA pressure are clinical variables that predict the development of this syndrome. The main clinical findings include dyspnea, congestive heart failure, PH, and large V waves on pulmonary capillary wedge pressure (PCWP) or LA pressure tracings in the absence of mitral regurgitation.

Echocardiographic Estimation of Left Atrial Pressure in Beagle Dogs with Experimentally-Induced Mitral Valve Regurgitation

Non-invasive and immediate estimation of left atrial pressure (LAP) is very useful for the management of mitral regurgitation (MR), and many reports have assessed echocardiographic estimations of LAP to date. However, it has been unclear of which examination and evaluate article possess the best accuracy for the MR severity. The present research aims to establish the echocardiographic estimation equation of LAP that is well applicable for clinical MR dogs. After the chordae tendineae rupture was experimentally induced via left atriotomy in six healthy beagle dogs (three males and three females, two years old, weighing between 9.8 to 12.8 kg), a radio telemetry transmitter catheter was inserted, which allows the continuous recordings of LAP without the use of sedation. Approximately 5 weeks after the surgery, echocardiographic examination, indirect blood pressure measurement, measurement of plasma atrial natriuretic peptide (ANP) and LAP measurement by way of the radio telemetry system was performed simultaneously. Subsequently, simple linear regression equations between LAP and each variable were obtained, and the equations were evaluated whether to be applicable for clinical MR dogs. As a result, the ratio of early diastolic mitral flow to early diastolic lateral mitral annulus velocity (E/Ea) had the strongest correlation as maximum LAP=7.03*(E/Ea)-54.86 (r=0.74), and as mean LAP=4.94*(E/Ea)-40.37 (r=0.70) among the all variables. Therefore, these two equations associated with E/Ea should bring more precise and instant estimations of maximum and mean LAP in clinical MR dogs.

A Novel Finding: The Left Atrial Substrate Property Is a Determinant of Left Atrial Compliance Changes after Catheter Ablation of Atrial Fibrillation

Introduction: The impact of the left atrial (LA) substrate property on the LA compliance before and after pulmonary vein isolation (PVI) is not clear. Methods: The study consisted of 10 patients (age 53±14) who underwent catheter ablation for atrial fibrillation. All patients received hemodynamic measurements of LA pressure and compliance. Electroanatomic LA bipolar voltage mapping was performed. The measurements were obtained before and after the PVI. Results: Before ablation, the LA pressure and compliance did not correlate with the LA mean voltage. After ablation (fluid load of 2200±540 cc and mean duration of 2.5 hours), the LA compliance (5.4±3.1 cm3/mmHg) increased in 4 patients (40%) and decreased or no change in 6 others (60%). The patients with increased compliance had a higher voltage (2.3±0.5 vs. 1.4±0.2 mV, P=0.03) and a smaller scar area (<0.5 mV, 10.3±8.5 vs. 32.9±9.2%, p=0.005). There was a linear relationship between the LA mean voltage and LA compliance after PVI. Conclusion: Catheter ablation and fluid loading unmask different hemodynamic responses of the LA. In patients with less atrial remodeling (higher voltage, fewer scar), PVI immediately improved the LA compliance. In patients with more atrial remodeling, the LA compliance worsened after ablation with fluid loading.

Implantable Sensors for Heart Failure

Heart failure (HF) affects more than 5 million Americans, and acute decompensated heart failure (ADHF) has emerged as the leading cause of hospitalization among people over the age of 65 years.1 Importantly, HF is a leading public health concern, and hospitalization expenses related to management of ADHF impose a substantial financial burden on the health care system. Additionally, readmission rates after hospitalization for ADHF may be as high as 50% at 6 months,2 and insights from the ADHERE registry suggest that a majority of patients admitted with ADHF have a history of heart failure.1 These data demonstrate that the majority of patients admitted with ADHF are known to the medical system and to medical providers, thereby creating an opportunity for upstream strategies that may be capable of detecting early HF destabilization and implementing therapies to restabilize the patient and avert hospitalization. The anticipated changes in the health care system—with a focus on bundled payments for disease management—will necessitate robust disease management programs to optimize therapy and minimize recurrent admissions once patients have been diagnosed with HF. Perhaps even more importantly, averting repeat episodes of ADHF is likely to have a stabilizing effect on the progression of HF and may improve long-term morbidity and mortality. The transition from chronic HF to ADHF involves perturbations in multiple intersecting processes including neurohormonal circuits, inflammatory mediators, cardiorenal interactions, and myocardial performance. Concurrently, derangements in comorbid illnesses such as coronary disease, atrial and ventricular arrhythmias, and hypertension also contribute to the pathophysiology of ADHF.3 Ultimately, these multiple pathways lead to an elevation in ventricular filling pressures and signs of vascular congestion, which, in concert with symptoms from impaired cardiac output, lead to the clinical constellation of ADHF. This pathophysiologic paradigm highlights multiple opportunities for detecting early changes in the processes that …

Monitoring of heart failure: comparison of left atrial pressure with intrathoracic impedance and natriuretic peptide measurements in an experimental model of ovine heart failure

Monitoring of HF (heart failure) with intracardiac pressure, intrathoracic impedance and/or natriuretic peptide levels has been advocated. We aimed to investigate possible differences in the response patterns of each of these monitoring modalities during HF decompensation that may have an impact on the potential for early therapeutic intervention. Six sheep were implanted with a LAP (left atrial pressure) sensor and a CRT-D (cardiac resynchronization therapy defibrillator) capable of monitoring impedance along six lead configuration vectors. An estimate of ALAP (LAP from admittance) was determined by linear regression. HF was induced by rapid ventricular pacing at 180 and 220 bpm (beats/min) for a week each, followed by a third week with daily pacing suspensions for increasing durations (1–5 h). Incremental pacing induced progressively severe HF reflected in increases in LAP (5.9 ± 0.4 to 24.5 ± 1.6 mmHg) and plasma atrial (20 ± 3 to 197 ± 36 pmol/l) and B-type natriuretic peptide (3.7 ± 0.7 to 32.7 ± 5.4 pmol/l) (all P<0.001) levels. All impedance vectors decreased in proportion to HF severity (all P<0.001), with the LVring (left ventricular)-case vector correlating best with LAP (r2=0.63, P<0.001). Natriuretic peptides closely paralleled rapid acute changes in LAP during alterations in pacing (P<0.001), whereas impedance changes were delayed relative to LAP. ALAP exhibited good agreement with LAP. In summary, impedance measured with an LV lead correlates significantly with changes in LAP, but exhibits a delayed response to acute alterations. Natriuretic peptides respond rapidly to acute LAP changes. Direct LAP, impedance and natriuretic peptide measurements all show promise as early indicators of worsening HF. ALAP provides an estimate of LAP that may be clinically useful.

Direct Left Atrial Pressure Monitoring in Severe Heart Failure: Long-Term Sensor Performance

We report the stability, accuracy, and development history of a new left atrial pressure (LAP) sensing system in ambulatory heart failure (HF) patients. A total of 84 patients with advanced HF underwent percutaneous transseptal implantation of the pressure sensor. Quarterly noninvasive calibration by modified Valsalva maneuver was achieved in all patients, and 96.5% of calibration sessions were successful with a reproducibility of 1.2 mmHg. Absolute sensor drift was maximal after 3 months at 4.7 mmHg (95% CI, 3.2–6.2 mmHg) and remained stable through 48 months. LAP was highly correlated with simultaneous pulmonary wedge pressure at 3 and 12 months (r = 0.98, average difference of 0.8 ± 4.0 mmHg). Freedom from device failure was 95% (n = 37) at 2 years and 88% (n = 12) at 4 years. Causes of failure were identified and mitigated with 100% freedom from device failure and less severe anomalies in the last 41 consecutive patients (p = 0.005). Accurate and reliable LAP measurement using a chronic implanted monitoring system is safe and feasible in patients with advanced heart failure.

Examining the Jugular Vein Is Never in Vain

In this issue of Circulation: Heart Failure , Drazner et al1 report the findings of their study on the relationship of right and left ventricular (LV) filling pressures in patients with heart failure and preserved LV ejection fraction (HFPEF) (also referred to as heart failure with preserved systolic function, diastolic heart failure). They noted good concordance (79%) in this patient population between right atrial pressure (RAP), indicative of right ventricular filling pressure, and pulmonary artery occlusive pressure (pulmonary capillary wedge pressure [PCWP]), indicative of LV filling pressure. These pressures, modulated by various loading and unloading maneuvers, ranged from low to normal to high. Nonconcordance was noted in only 21% of the measurements, and, in these, the PCWP did not match the elevation of RAP. Article see p 202 The weaknesses and limitations of this study are overshadowed by its strengths. PCWP is not a direct measurement of left atrial pressure, and RAP and PCWP are not direct measurements of right and LV filling pressures, respectively. But their relationships (RAP to right ventricular filling pressure; PCWP to left atrial pressure and LV filling pressure) are closely linked, and correlations are generally quite high,2–5 such that RAP and PCWP are routinely used in clinical medicine as respective indicators of right and LV filling pressures. Only 11 patients with HFPEF were studied by Drazner et al.1 However, the study was performed in an experienced laboratory by seasoned investigators of human heart failure, using the standard techniques to generate a spectrum of ventricular-loading conditions. The lead author has a noteworthy record of studying fundamental hemodynamic questions in human heart failure.6–9 The question itself, namely the relationship between right and left heart filling pressures, had not been adequately examined in HFPEF. The favorable concordance of right and left heart filling pressures …

The Relationship Between Pulmonary Artery and Pulmonary Capillary Wedge Pressure for the Diagnosis of Pulmonary Vascular Disease

Left heart disease and pulmonary vascular disease (PVD) both lead to raised pulmonary artery pressure (PAP) but differ in pathophysiology, prognosis and treatment. There are currently no criteria for diagnosing PVD in the presence of left heart disease. We therefore studied the relationship between PAP and pulmonary capillary wedge pressure (PCWP, a measure of left atrial pressure) to help define when PAP should be considered 'out-of-proportion' to PCWP, thus suggestive of PVD. Retrospective analysis of 898 consecutive simultaneous left and right heart catheterisations. Of these, 684 patients (age 63+/-14 years) were classified according to presence of absence of left heart disease. Multilinear regression explored the relationship between mean PAP and PCWP, age, gender, systemic haemodynamics and left heart disease diagnosis. Increasing PCWP, age and heart rate and female gender were associated with higher PAP (p<0.0001, p=0.049, p<0.0001 and p=0.0015, respectively). Thus, in males: (mean PAP)=0.94+[1.15 x (mean PCWP)]+[0.03 x (age)]+[0.07 x (heart rate)] (for females add 1.38 mm Hg). This model accounted for 75% of variability in PAP, with PCWP alone accounting for 74%. A strong linear relationship exists between PAP and PCWP, which may help identify PAP 'out-of-proportion' to PCWP, facilitating the diagnosis of PVD in patients with pulmonary hypertension and left heart disease.

Echocardiographic Evaluation of Diastolic Function Can Be Used to Guide Clinical Care

For normal cardiac performance, the left ventricle (LV) must be able to eject an adequate stroke volume at arterial pressure (systolic function) and fill without requiring an elevated left atrial (LA) pressure (diastolic function). These systolic and diastolic functions must be adequate to meet the needs of the body both at rest and during stress. Response by Tschope and Paulus on p 809 Systolic function is conveniently (although not always accurately) measured as the ejection fraction (EF), calculated as stroke volume divided by end-diastolic volume.1 The LV EF is easily interpreted. The lower limit of normal is ≈50%. The lower the EF is, the greater the reduction in systolic function. Diastolic function has been more difficult to evaluate.2 Traditionally, invasive measures of LV diastolic pressure-volume relations and the rate of LV pressure fall during isovolumetric relaxation have been used. However, these methods are not practical for routine clinical use and do not adequately evaluate all aspects of diastolic filling.3 Comprehensive echocardiographic evaluation of the dynamics of LV filling using blood pool and tissue Doppler has now progressed so that it provides clinically important information that can be used to direct patient care. We present data that support the use of echocardiographic evaluation of diastolic function to recognize cardiac dysfunction in patients with heart failure, especially those with preserved EF; to guide the management of patients by identifying those with and without elevated left filling pressures regardless of underlying EF; and to determine prognosis in a wide variety of patient populations. Although the LV end-diastolic pressure-volume relation describes the passive properties of the LV, LV filling is not a passive or slow process.3 In fact, the peak flow rate across the mitral valve is equal to or greater than the peak flow rate across the aortic valve. …

Daily Rhythms of Left Atrial Pressure in Beagle Dogs with Mitral Valve Regurgitation

Mitral valve regurgitation (MR) causes increased left atrial pressure (LAP) and is associated with occurrence of clinical signs. It will be useful to understand diurnal variations of LAP for the management of MR. Circulatory parameters and diurnal rhythm are linked to clinical signs in cardiac diseases. LAP also exhibits a diurnal rhythm in dogs with MR. Five healthy Beagle dogs weighing 9.8-12.8 kg (3 males and 2 females; aged 2 years) were used. A radiotelemetry system for continuous measurement of LAP was used in this study. Rupture of the chordae tendineae was experimentally induced via left atriotomy, and a transmitter catheter was inserted into the left atrium. The body of the transmitter was implanted SC. After clinical condition was stabilized, the severity of MR was evaluated by echocardiography, and LAP was recorded for 72 consecutive hours for the analysis of diurnal variation. Abrupt increases in LAP, which averaged 16.7 mmHg, were observed at feeding periods. In contrast, strong diurnal LAP variations were found, with a significant but slight increase in daytime LAP compared with nighttime LAP. Diurnal LAP is characterized by a slight but significant nocturnal decrease and abrupt increases in response to excitation. The latter seemed to be more important considering the relationship with clinical manifestations. The clinical relevance of exercise restriction in the management of MR was acknowledged.

The Relationship of Left Atrial Volume and Left Atrial Pressure in Patients With Hypertrophic Cardiomyopathy: An Echocardiographic and Cardiac Catheterization Study

Left atrial enlargement is a marker of diastolic dysfunction, which is present in most patients with hypertrophic cardiomyopathy (HCM). It is unclear as to whether left atrial volume is a reliable measure of ventricular filling pressures in these patients. Left atrial volume index (LAVI) was measured in 100 symptomatic patients with HCM using transthoracic echocardiography, followed by cardiac catheterization with transseptal measurement of left atrial pressure (LAP) and end-diastolic pressure within 48 hours. LAVI was only modestly related to mean LAP (r=0.24, P=.02), and there was no significant relation to end-diastolic pressure (r=0.11, P=.28). The specificity of increased LAVI (>28 cm3/m2) for elevated LAP (>15 mm Hg) was poor (16%). However, all patients with normal LAVI had normal LAP. Although left atrial size may reflect chronic changes due to diastolic dysfunction in HCM, the relation of increased LAVI to ventricular filling pressures is modest. Nonetheless, a normal LAVI suggests normal ventricular filling pressures in patients with HCM.

Direct Left Atrial Pressure Monitoring in Ambulatory Heart Failure Patients

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

Evaluation of Left Ventricular Filling Pressures by Doppler Echocardiography in Patients With Hypertrophic Cardiomyopathy

Diastolic dysfunction is a major pathophysiological abnormality in hypertrophic cardiomyopathy (HCM). Doppler echocardiographic parameters correlate with left ventricular (LV) filling pressures in other diseases, but it is unclear whether these findings apply to patients with HCM, who have multiple complex interrelated events leading to diastolic dysfunction. This study compares Doppler echocardiographic estimates of filling pressures to direct measurements of left atrial pressure (LAP) via catheterization in 100 patients with HCM. One hundred patients who were symptomatic with HCM (New York Heart Association class III/IV, 82%) underwent measurement of early diastolic transmitral flow velocity (E) and mitral annular velocities (e') with the use of transthoracic echocardiography within 48 hours of cardiac catheterization with direct measurement of LAP. In a subset of 42 patients, echocardiographic and catheterization measurements were performed simultaneously. Mean LAP directly correlated with medial E-e' ratio in the overall population (r=0.44, P<0.0001) and also in the subgroup of patients who had simultaneous echocardiographic and catheterization studies (r=0.28, P=0.07). However, scatter was present. A calculated mean LV filling pressure was derived from the E-e' ratio with the use of a previously described regression equation, and the 95% confidence limits of agreement with measured mean LAP exceeded +/-18 mm Hg both for the overall group and for the subgroup who had simultaneous studies. Similar results were obtained with the lateral E-e' ratio. Only 1 patient had a previously defined "normal" E-e' ratio of <8. In symptomatic patients with HCM, Doppler echocardiographic estimates of LV filling pressure with the use of transmitral flows and mitral annular velocities correlate modestly with direct measurement of LAP. Given the complex nature of diastolic dysfunction in HCM, precise characterization of LV filling pressure in an individual patient cannot be determined with the use of these noninvasive parameters.

Accurate Non-Invasive Calibration of an Implantable Left Atrial Pressure Monitoring System in Heart Failure Patients During Long-Term Follow-Up

not been defined. We investigated whether BNP levels in stable heart failure (HF) patients reflect fluctuations in left atrial pressure (LAP). Methods: Nine outpatients with NYHA II–III HF and an implanted monitoring system measuring direct LAP underwent serial recordings of LAP and BNP. LAP measurements were obtained at the time of venesection, 4 h prior and 12-hourly in the 72h prior to venesection. This was repeated on up to eight occasions during 1 year of follow-up. Intra-patient correlation coefficients of variation (CV) were calculated to relate LAP levels at varying lags from venesection, to BNP andNT-BNP levels at venesection, across sampling occasions. Results: 3–8 serial recordings of LAP and BNP were obtained in all subjects. Despite having stable symptoms there was considerable variability in LAP within sampling occasions (CV 20–65%). BNP levels correlated with LAP at the time of venesection (r= 0.45; p< 0.0001), while NT-proBNP correlated with LAP 4h prior to venesection (r= 0.74; p< 0.001). Intra-individual CVs ranged from 9 to 43% for BNP and 8–86% for NT-proBNP. The intraindividual variation of BNP or NT-proBNP levels over the follow-up period were significantly related to the CV of LAP measurements (r= 0.53; p< 0.01, r= 0.8; p< 0.01, respectively). Conclusion: In ambulant patients with stable HF, variability in BNP and NT-proBNP levels is strongly related Results: VMs were successful on 437/498 (90%) occasions and all patients achieved successful Valsalva calibration. At 11± 5 months follow-up, 24/25 implants had minor offset drift (mean 2± 5mmHg) resolving at 3 months consistent with device healing. One patient with significant drift had a clinically usable device, as drift was predictable and easily corrected. During RHC device LAP measured PCWP within −0.2± 5.7mmHg. All offset drift since implantation was corrected by VM calibration. Conclusion: The VMwaswell tolerated and allowed accurate, clinically useful non-invasive calibration of a new LAP monitoring system. Minimal drift was reliably corrected using this simple method. doi:10.1016/j.hlc.2007.06.057