Reduction In Left Atrial Pressure Research Articles

Can patients be selected for transcatheter edge-to-edge repair based on the baseline transmitral gradient?

Key Points Baseline transmitral gradient can predict reduction in left atrial pressure and residual transmitral gradient after transcatheter edge‐to‐edge repair (TEER). Understanding the possible multiple causes of elevated transmitral gradient before and after TEER may be important for selecting patients. Further research is necessary to elucidate the complex interaction of mitral regurgitation, the mitral annulus, left atrial, and ventricular function and their response to TEER.

The impact of baseline transmitral diastolic mean gradient on left atrial pressure reduction in patients undergoing transcatheter mitral valve edge-to-edge repair.

Elevated transmitral gradient post transcatheter mitral valve edge-to-edge repair (TEER) has been associated with worse outcomes. Whether an elevated baseline transmitral diastolic mean gradient (MG) ≥5 mmHg is associated with hemodynamic outcomes after TEER is unknown. A total of 164 consecutive patients undergoing TEER at Mayo Clinic between June 2014 and May 2018 were analyzed in this retrospective study. Baseline demographics, as well as clinical, echocardiographic, and procedural data were obtained. Data on direct left atrial pressure (LAP) before and after TEER were recorded. Logistic regression models were constructed to evaluate the association between preprocedure transmitral diastolic mean gradient (pre-MG) and (1) improvement in LAP following TEER, (2) postprocedure transmitral diastolic mean gradient (post-MG). A decrease in LAP post TEER was considered an improvement in hemodynamic response. Pre-MG was categorized as: ≥5and <5 mmHg. Median age of the cohort was 81.5 years (Q1: 76.3, Q3: 87) and 34% were female. At baseline, median transmitral diastolic MGwas 4 mmHg (Q1: 3, Q3: 5) and median LAPwas 19 mmHg (Q1:16, Q3: 23.5). In a multivariable model, adjusted for age and sex, patients with pre-MG ≥ 5 mmHg were less likely to see an improvement in LAP post TEER(adjusted odds ratio [aOR]: 0.22, 95% confidence interval [CI]: 0.09, 0.55; p = 0.001) and more likely to have elevated post-MG (aOR; 7.08, 95% CI: 2.93, 17.13; p < 0.001). Higher pre-MG (≥5 mmHg) was associated with a lower reduction in LAP and higher residual transmitral gradient following TEER suggesting other potential contributors to increased LAP besides mitral regurgitation as a cause of elevated baseline MG.

Left ventricular venting in veno-arterial extracorporeal membrane oxygenation: A computer simulation study.

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is the fastest way to restore circulation in refractory cardiogenic shock, however it cannot unload the failing left ventricle. There is a lack of consensus regarding optimal approach to left ventricular venting in V-A ECMO patients with severely depressed or absent left ventricular function. A computer model was developed in Matlab Simulink R20016b (MathWorks, Inc., Natick, MA, USA) to analyze different venting options as well as atrial septostomy in the setting of cardiogenic shock and V-A ECMO. The model has shown an inverse linear relationship between left atrial pressure and either vent, Impella or atrial septum defect flow rate. The minimum vent flow required to prevent pulmonary edema in complete loss of left ventricular function needed to be higher than the bronchial blood flow. Atrial septostomy restored normal pulmonary blood flow with low left atrial pressure but induced stasis in the left ventricle. Venting the pulmonary artery induced stasis in the entire pulmonary circulation as well as left atrium and left ventricle. Venting the left ventricle directly with a cannula or Impella device avoided blood stasis. Our data suggest that reduction of left atrial pressure is linearly related to the vent, Impella or atrial septal defect flow rate. The preferred vent location is the left ventricle as it avoids stasis in the pulmonary circulation and cardiac chambers.

The Impact of Increased Baseline Transmitral Diastolic Mean Gradient on Left Atrial Pressure Reduction in Patients Undergoing Transcatheter Mitral Valve Edge-to-Edge Repair

The Impact of Increased Baseline Transmitral Diastolic Mean Gradient on Left Atrial Pressure Reduction in Patients Undergoing Transcatheter Mitral Valve Edge-to-Edge Repair

Comparison of device-based therapy options for heart failure with preserved ejection fraction: a simulation study

Successful therapy of heart failure with preserved ejection fraction (HFpEF) remains a major unmet clinical need. Device-based treatment approaches include the interatrial shunt device (IASD), conventional assist devices pumping blood from the left ventricle (LV-VAD) or the left atrium (LA-VAD) towards the aorta, and a valveless pulsatile assist device with a single cannula operating in co-pulsation with the native heart (CoPulse). Hemodynamics of two HFpEF subgroups during rest and exercise condition were translated into a lumped parameter model of the cardiovascular system. The numerical model was applied to assess the hemodynamic effect of each of the four device-based therapies. All four therapy options show a reduction in left atrial pressure during rest and exercise and in both subgroups (> 20%). IASDs concomitantly reduce cardiac output (CO) and shift the hemodynamic overload towards the pulmonary circulation. All three mechanical assist devices increase CO while reducing sympathetic activity. LV-VADs reduce end-systolic volume, indicating a high risk for suction events. The heterogeneity of the HFpEF population requires an individualized therapy approach based on the underlying hemodynamics. Whereas phenotypes with preserved CO may benefit most from an IASD device, HFpEF patients with reduced CO may be candidates for mechanical assist devices.

CRT-700.57 The Impact of Increased Baseline Transmitral Diastolic Mean Gradient on Left Atrial Pressure Reduction in Patients Undergoing Transcatheter Mitral Valve Edge-to-Edge Repair

CRT-700.57 The Impact of Increased Baseline Transmitral Diastolic Mean Gradient on Left Atrial Pressure Reduction in Patients Undergoing Transcatheter Mitral Valve Edge-to-Edge Repair

Right-to-Left Shunt Through Iatrogenic Atrial Septal Defect After MitraClip Procedure

ObjectivesThe aim of this study was to investigate the incidence, characteristics, hemodynamic conditions, and clinical significance of right-to-left (R-L) shunt through an iatrogenic atrial septal defect (iASD) after the MitraClip procedure. BackgroundR-L shunt through an iASD after the MitraClip procedure has not been well investigated. MethodsFrom 2014 to 2017, 385 consecutive patients with mitral regurgitation underwent the MitraClip procedure. iASD was assessed using intraprocedural transesophageal echocardiography. Right and left heart catheterization was used to assess the hemodynamic status of patients. All patients provided written informed consent for the procedure. All data for this study were collected from an established interventional cardiology laboratory database approved by the Cedars-Sinai Medical Center Institutional Review Board. ResultsR-L shunt was observed in 20 patients (5%). In 7 of these patients (35%), R-L shunt was accompanied by acute deoxygenation. Prevalence of severe tricuspid regurgitation (55% vs. 20%; p = 0.001), serum B-type natriuretic peptide (664 pg/ml [434 to 1,169 pg/ml] vs. 400 pg/ml [195 to 699 pg/ml]; p = 0.006), mean pulmonary artery pressure (38 mm Hg [34 to 45 mm Hg] vs. 29 mm Hg [22 to 37 mm Hg]; p < 0.001), and right atrial pressure (19 mm Hg [13 to 20 mm Hg] vs. 10 mm Hg [7 to 14 mm Hg]; p < 0.001) were significantly higher in patients with R-L shunt than in those with left-to-right shunt. Patients with R-L shunt also showed a more prominent reduction in the left atrial V-wave and mean pressure from baseline to post-procedure compared with those with left-to-right shunt (−22.8 ± 2.6 mm Hg vs. −11.8 ± 0.9 mm Hg [p = 0.002] and −7.9 ± 0.8 mm Hg vs. −4.0 ± 0.4 mm Hg [p = 0.003], respectively). ConclusionsR-L shunt through an iASD was observed in 5% of patients who underwent the MitraClip procedure and in one-third of patients with R-L shunt presented acute deoxygenation. Elevated right atrial pressure concomitant with pulmonary hypertension and significant reduction in left atrial pressure after MitraClip deployment were associated with R-L shunt.

The Hole of Hope: Balloon Atrial Septostomy for Left Ventricle Unloading during VA ECMO

Veno arterial extracorporeal membrane oxygenation (VA-ECMO) is an established rescue therapy for cardiogenic shock (CS). However, the increase in left ventricle (LV) afterload associated with inappropriate LV unloading remains an unsolved problem. Balloon atrial septostomy (BAS) is an inexpensive effective with low complication rates. Our purpose was to understand BAS effect in this setting. Observational retrospective study, including patients submitted to BAS for LV unloading during VA-ECMO support due to CS between 2018 and 2019. Inotropic use was evaluated by the Wernovsky inotropic score. Statistical analysis was performed by median comparison with Wilcoxon test for related samples. Four patients with refractory CS despite VA-ECMO and intra aortic balloon pump (n=3) or Impella (n=1) support were included. The age of the patients was 55.5 years (IQR 46.8-64.3) and 75% were male. The basal median LV ejection fraction was 29.5%. All had severe functional mitral regurgitation and ischemic heart disease (n=3) or severe aortic stenosis (n=1). BAS was performed after a median time of 8 days (IQR 5.5-12.0) after ECMO with a final dimension of 5 mm. The reduction in left atrial pressure led to resolution of pulmonary edema in all patients. There was a hemodynamic improvement after the procedure, with lower inotropic use in 75% of patients (median difference -0,6; p= 1.00), and reduction in pulmonary pressures and lactate levels (Table 1). Additionally we documented an increase in LV outflow tract (LVOT) velocity time integral (VTI) and in the PaO2/FiO2 ratio. After a follow-up of 25.5 days (IQR 12.8-45.8) half of the patients were weaned from VA-ECMO or transplanted. One procedure was complicated by a femoral hematoma. Percutaneous BAS is a simple and effective procedure to treat refractory pulmonary edema during VA-ECMO support. The improvement in LV performance, documented by the increase in LVOT VTI, is likely due to improvement in intracavitary pressures and a better oxygenation.

P753 Impact of transcatheter aortic valve implantation on concomitant mitral regurgitation in patients with severe aortic stenosis

Abstract Background Severe aortic stenosis (AS) and functional mitral regurgitation (MR) frequently coexist. There is no consensus about the optimal therapeutic strategy for patients with combined valve disease. Evidence has shown that double valve surgery is associated with high complication rates and mortality, whereas MR severity may improve after transcatheter aortic valve implantation (TAVI). Purpose Aim of our study was to evaluate hemodynamic parameters and cardiac function in patients with severe AS and concomitant MR undergoing TAVI. Methods We prospectively enrolled consecutive TAVI patients with concomitant MR. Exclusion criteria were primary cardiomyopathies, prior valve surgery, permanent atrial fibrillation and inadequate echocardiographic imaging. Echo-Doppler assessment, including global longitudinal strain (GLS) and peak atrial longitudinal strain (PALS) (absolute value), was performed before TAVI and after 1-3 months. MR grading was assessed according to quantitative methods (vena contracta and/or PISA). Changes (Δ) of the main echo parameters before and after intervention were computed. On the basis of MR grading changes, the study population was divided in two groups: no improvement in MR grading (NIMR) and improvement in MR grading (IMR). Results Of 49 included patients (M/F = 20/29, age 80.7 ± 5.6 years), 23 had mild MR and 26 moderate to severe MR before TAVI. After the procedure, MR grading improved in 11 (IMR) and remained stable in 38 (NIMR) patients. The two groups were comparable for sex, age, body mass index, blood pressure and heart rate. After TAVI, both groups showed an improvement in GLS (17.8 ± 4.7 to 20.1 ± 4.4%, p &amp;lt; 0.0001 and 16.8 ± 3.8 to 19.0 ± 3.1%, p &amp;lt; 0.01, in NIMR and IMR respectively) and in PALS (20.4 ± 7.4 to 24.2 ± 7.3%, p &amp;lt; 0.0001 in NIMR and 19.5 ± 4.5 to 26.7 ± 6.1%, p &amp;lt; 0.001, in NIMR and IMR respectively), without significant changes in ejection fraction (p = 0.12). Only in IMR group, a significant decrease of systolic pulmonary arterial pressure (sPAP) (45.5 ± 10.6 to 36.3 ± 6.9 mmHg, p &amp;lt; 0.001) and left atrial volume index (54.9 ± 14.8 to 48.9 ± 13.3 ml/m², p &amp;lt; 0.01) was observed after TAVI. Changes of sPAP (ΔsPAP) (9.1 ± 6.4 vs. -0.07 ± 6.7, p &amp;lt; 0.0001) was higher and ΔPALS (-7.2 ± 5.1 vs. -3.8 ± 4.3, p &amp;lt; 0.03) lower in IMR compared with NIMR group (Figure). By a multiple linear regression analysis performed in the pooled population, after adjusting for ΔPALS, Δ aortic valve area and ΔGLS, the association between ΔsPAP and MR grading improvement remained significant (beta = 0.53, p &amp;lt; 0.001) (cumulative R²=0.31, SEE = 6.9 mmHg, p = 0.007). Conclusion Afterload reduction following TAVI may induce hemodynamic changes determining also a reduction in MR severity. This mechanism implies a reduction in left atrial pressure, whose PALS is a reliable marker, and a consequent reduction of post-capillary pulmonary hypertension. The association between MR improvement and ΔsPAP reduction is independent on echocardiographic confounders. Abstract P753 Figure. ΔsPAP and ΔPALS in NIMR and IMR

Per-operative Changes of Pulmonary Artery Pressure following Closed Mitral Commissurotomy

Background: Mitral stenosis is often present with pulmonary hypertension. Closed Mitral Commissurotomy (CMC) is a treatment of choice for severe mitral stenosis. In this study, we examined the per-operative changes of pulmonary artery pressure following opening of stenosed mitral valve.&#x0D; Methods: All these CMCs were performed routinely through the left antero-lateral thoracotomy (4th intercostal space) and dilatation was done by metallic Tubb’s Dilator. Peroperative left atrial and Pulminary Arterial pressures were measured before and after dilatation.&#x0D; Results: 15 patients had undergone CMC. Following CMC, per-operative mean Pulmonary artery pressure was reduced from 45.5±7.1 mm of Hg to 39.0±8.8 mm of Hg (p=0.043). Mean left atrial pressure reduced from 35.9±5.6 mm of Hg to 30.0±9.1 mm of Hg (p = 0.049). At three months follow up after closed mitral commissurotomy mitral valve area at echocardiography was found 2.29±0.18 cm2. There was no case of death after closed mitral commissurotomy. Mild mitral regurgitation occurred in 1 patient.&#x0D; Conclusion: We conclude that there is immediate significant reduction of pulmonary Artery pressure following closed mitral commissurotomy. This reduction is apparently comparable with a similar reduction of left atrial pressure.&#x0D; Cardiovasc. j. 2019; 11(2): 147-151

Reduction of sleep-disordered breathing following effective percutaneous mitral valve repair with the MitraClip system.

This study tested the hypothesis that a reduction of pulmonary congestion achieved by a reduction of mitral regurgitation (MR) severity in heart failure (HF) patients is associated with reduced event lengths of sleep-disordered breathing (SDB). We prospectively enrolled 20 consecutive HF patients who underwent MitraClip implantation. Patients underwent cardiorespiratory polygraphic recording prior to and after percutaneous mitral valve repair (PMVR). Beyond routinely established indicators of apneas and hypopneas per hour (respiratory event index), we manually analyzed apnea event lengths. MitraClip implantation led to marked reduction of MR severity and a reduction in left atrial pressure. These hemodynamic changes were accompanied by changes in SDB: the subtype of SDB switched from CSA to OSA in 4 patients. Likewise, quantitative indicators of SDB were altered in both forms of SDB with a reduction in circulatory delay (CSA 38 ± 14 vs. 33 ± 15s.; p = 0.002 and OSA 34 ± 9 vs. 28 ± 6s.; p = 0.02) and a corresponding reduction in ventilation lengths in CSA patients (42 ± 15 vs. 37 ± 13s.; p = 0.05). A reduction of pulmonary congestion as achieved by a decrease of left atrial pressure through successful MitraClip implantation is associated with a reduction in respiratory event lengths, further pointing towards a relation between SDB and HF.

Update on Devices for Diastolic Dysfunction: Options for a No Option Condition?

This article provides an update on percutaneous devices to treat diastolic dysfunction, current clinical experience, and actively enrolling trials. We also discuss potential complications and limitations of devices. Exertional symptoms including exertional dyspnea and exercise intolerance are common features of heart failure that are driven by left ventricular and left atrial non-compliance that results in pulmonary vascular congestion. Multiple studies that have shown that reducing total body volume and intravascular pressure, using pharmacologic therapies, are associated with improved outcomes among patients who have heart failure with reduced ejection fraction (HFrEF) (ejection fraction [EF] < 40%), but not heart failure with preserved ejection fraction (HFpEF) (EF > 55%).This is related to the fact that HFpEF is associated with altered diastolic compliance but not volume overload, which presents as exertional increases in left atrial pressure. Exercise assessment of LA and pulmonary pressures are not commonly assessed today in the clinic or in the catheterization laboratory. As elevated left atrial pressure mediates these symptoms, selective reduction in left atrial pressure may provide improvement in symptoms without complications of pharmacologic therapy such as diuresis and aggressive blood pressure reduction. Mechanical devices that aim to reduce left atrial pressure have been developed and evaluated in HFpEF and HFrEF patients. The current data from the small number of patients who have undergone treatment with left atrial decompression devices indicate that they have a high rate of success and may improve patient's exercise capacity. Larger, controlled trials are underway to better understand the role of these devices in patients with diastolic dysfunction.

The last frontier: transcatheter devices for percutaneous or minimally invasive treatment of chronic heart failure.

Heart failure has a high prevalence in the general population. Morbidity and mortality of heart failure patients remain high, despite improvements in drug therapy, implantable cardioverter-defibrillators and cardiac resynchronisation therapy. New transcatheter implantable devices have been developed to improve the treatment of heart failure. There has been a rapid development of minimally invasive or transcatheter devices used in the treatment of heart failure associated with aortic and mitral valve disease and these devices are being incorporated into routine clinical practice at a fast rate. Several other new transcatheter structural heart interventions for chronic heart failure aimed at a variety of pathophysiologic approaches are currently being developed. In this review, we focus on devices used in the treatment of chronic heart failure by means of left ventricular remodelling, left atrial pressure reduction, tricuspid regurgitation reduction and neuromodulation. The clinical evaluations of these devices are early-stage evaluations of initial feasibility and safety studies and additional clinical evidence needs to be gathered in appropriately designed clinical trials.

Rationale and Design of the Reduce Elevated Left Atrial Pressure in Patients With Heart Failure (Reduce LAP-HF) Trial

ObjectiveHeart failure with preserved ejection fraction (HFpEF) is characterized by elevated left atrial pressure during rest and/or exercise. The Reduce LAP-HF (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) trial will evaluate the safety and performance of the Interatrial Shunt Device (IASD) System II, designed to directly reduce elevated left atrial pressure, in patients with HFpEF. MethodsThe Reduce LAP-HF Trial is a prospective, nonrandomized, open-label trial to evaluate a novel device that creates a small permanent shunt at the level of the atria. A minimum of 60 patients with ejection fraction ≥40% and New York Heart Association functional class III or IV heart failure with a pulmonary capillary wedge pressure (PCWP) ≥15 mm Hg at rest or ≥25 mm Hg during supine bike exercise will be implanted with an IASD System II, and followed for 6 months to assess the primary and secondary end points. Safety and standard clinical follow-up will continue through 3 years after implantation. Primary outcome measures for safety are periprocedural and 6-month major adverse cardiac and cerebrovascular events (MACCE) and systemic embolic events (excluding pulmonary thromboembolism). MACCE include death, stroke, myocardial infarction, or requirement of implant removal. Primary outcome measures for device performance include success of device implantation, reduction of PCWP at rest and during exercise, and demonstration of left-to-right flow through the device. Key secondary end points include exercise tolerance, quality of life, and the incidence of heart failure hospitalization. ConclusionReduce LAP-HF is the first trial intended to lower left atrial pressure in HFpEF by means of creating a permanent shunt through the atrial septum with the use of a device. Although the trial is primarily designed to study safety and device performance, we also test the pathophysiologic hypothesis that reduction of left atrial pressure will improve symptoms and quality of life in patients with HFpEF.

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.

The Impact of Pulmonary Venous Hypertension on the Pulmonary Circulation in the Young

Pulmonary venous hypertension is a well-characterized cause of pulmonary hypertension in adults, but little is known regarding the relationship between left atrial pressure and pulmonary arteriolar resistance in the young. Also, in adults relief of pulmonary venous hypertension results in a marked fall in pulmonary arteriolar resistance, but this could be different in children because vascular changes are more severe in young patients than adults with mitral stenosis. We inspected records of children at Children's Hospital Boston having mitral balloon valvuloplasty, and patients ≤5 years old having mitral valve replacement, to determine (1) the relationship between left atrial pressure and pulmonary arterial pressure and resistance (n = 94 children, median age 17.8 months) and (2) how pulmonary arteriolar resistance changes after mitral valve replacement. The average indexed pulmonary arteriolar resistance was 7.8 ± 5.9 units and was unrelated to age but was positively related to left atrial pressure. There was great variability in pulmonary arteriolar resistance for any given left atrial pressure. Pulmonary arterial pressure (n = 16) and pulmonary arterial resistance (n = 9) were measured before and after mitral valve replacement (median = 29.4 months old). Despite preoperative indexed pulmonary arterial resistance of ≥5 units in 11 of 15 patients, postoperative pulmonary arterial pressure was substantially lower in all save three, and two patients with high pulmonary arterial pressure still had high left atrial pressure postoperatively (25 mmHg). We conclude that in young children, as in adults, pulmonary arterial resistance generally falls greatly with reduction in left atrial pressure.

Evaluation of Left Ventricular Assist Device Performance and Hydraulic Force in a Complete Mock Circulation Loop

Centrifugal pump performance characteristics are vital in determining the ability of a prototype left ventricular assist device (LVAD) to meet the physiological circulation requirements of the cardiovascular system. These characteristics influence the static hydraulic forces encountered by the pump impeller, which determine the required load stiffness of suspension type bearings to minimize impeller touchdown. Performance investigations were conducted on an LVAD design while characterizing the impeller static hydraulic forces of various impeller/volute configurations. The pumps were inserted into a complete systemic and pulmonary mock circulation rig configured to provide suitable nonpulsatile or simulated pulsatile left heart failure environments. The single volute and closed shroud impeller configuration exhibited lowest radial (0.01 N) and axial (3 N) force at nonpulsatile design flow conditions, respectively. Normal hemodynamic conditions of 5.1 L/min at 94 mm Hg were re-established upon inserting the device into the left heart failure environment, where the pump operated along the nonpulsatile characteristic curve for 2200 rpm. The operational limits on this curve were dictated by the required pressure differential across the pump during systolic and diastolic periods. The reduction of left atrial pressure (25 to 8 mm Hg) indicated the alleviation of pulmonary congestion. The ability for the LVAD to support circulation in a left heart failure environment was successfully demonstrated in the mock circulation loop. The impeller hydraulic force characteristics attained will aid the bearing designer to select the best volute and impeller configuration to minimize impeller touchdown in magnetic, hydrodynamic or mechanical type bearing applications.

Usefulness of percutaneous balloon mitral commissurotomy in preventing the development of atrial fibrillation in patients with mitral stenosis

A prospective cohort of patients with mitral stenosis and no history of atrial arrhythmias showed no decrease in the incidence of atrial fibrillation (AF) after successful versus unsuccessful Inoue balloon percutaneous balloon mitral valve commissurotomy. Advanced age and left atrial dimension best predicted which patients developed AF during follow-up, whereas percutaneous balloon mitral valve commissurotomy procedural success and left atrial pressure reduction did not have an impact on incidence of AF.

Anastomosis between the left atrial appendage and left superior vena cava in a patient with mitral atresia.

A 5-day-old boy with mitral atresia and restrictive interatrial communication underwent an anastomosis between the left atrial appendage and left superior vena cava draining to the right atrium after unsuccessful balloon atrial septostomy. Consequent reduction of left atrial pressure improved the child's clinical condition, enabling palliative surgery. This procedure may be done safely without cardiopulmonary bypass in a seriously ill patient with combined elevated left atrial pressure and persistent left superior vena cava.

The effect of aortic valve replacement on N-terminal natriuretic propeptides in patients with aortic stenosis.

Increased plasma concentrations of natriuretic peptides have been demonstrated to be associated with increased intracardiac pressure and left ventricular (LV) hypertrophy. After aortic valve replacement (AVR) in aortic stenosis patients, there is a relief of the left outflow obstruction with a substantial hemodynamic improvement. This is followed by a gradual regression of the LV hypertrophy. After AVR, reduction in LV filling pressure is expected to occur rapidly, while regression of LV hypertrophy will take place over a longer time period. On this basis we hypothesized that the plasma levels of N-terminal proatrial natriuretic peptide (NT-proANP) would be reduced early in the postoperative period, while N-terminal probrain natriuretic peptide (NT-proBNP), through its closer reflection of LV hypertrophy, would be sustained for a longer period. Two groups of patients with aortic stenosis undergoing AVR were followed for 4 and 12 months, respectively. Plasma concentrations of NT-proANP and NT-proBNP were measured before and after AVR and related to preoperative findings and changes in the aortic valve area index. Before AVR, the patients had significantly increased plasma levels of NT-proANP and NT-proBNP. After AVR, NT- proANP was decreased at 4 and 12 months but remained elevated compared with controls. N-terminal-proBNP tended to decrease, but did not change significantly. When the patients were followed for 12 months, only those with elevated preoperative pulmonary capillary wedge pressure had decreased peptide levels (NT-proANP: p = 0.017, NT-proBNP: p = 0.058). There was no regression of LV hypertrophy. The patients with the largest postoperative valve area index [1.27 (1.10-1.55) cm2/m2] had the largest reduction of NT-proBNP (47%). Those with the smallest valve area index [0.67 (0.54-0.73) cm2/m2] had no decrease in NT-proBNP. Our study suggests that a reduction in left atrial pressure is the main factor causing the change of NT-proANP level after AVR. A small prosthetic valve orifice area with a high aortic valve gradient might prevent regression of LV hypertrophy, thus representing a stimulus for increased cardiac secretion of NT-proBNP.