We sought to assess the feasibility of recording the myocardial velocity gradients (MVGs) and mean myocardial velocities (MMVs) measured by color M-mode tissue Doppler imaging (TDI) in the free wall of unsedated normal cats (n = 18) with a 7.4-MHz probe equipped to record TDI images. The peak MVG and ...

OBJECTIVES: The opening pressure and the resistance of a CSF shunt are essential for clinical use in order to set the proper opening pressure and to determine the shunt function in vivo. We find it of vital importance to validate and supplement the product description given by the manufacturer. The ...

BACKGROUND: It has been reported that aortic regurgitation, mitral valve regurgitation, or both are associated with lower body mass index, an index of body adiposity. However, the relations of valvular regurgitation to body composition and myocardial bioenergetic expenditure have not been previously investigated in a population-based sample. METHODS: We selected ...

OBJECTIVE: To evaluate cardiac function in structurally and chromosomally normal fetuses with increased nuchal translucency (NT). METHODS: Forty-two structurally and chromosomally normal fetuses with increased NT at 11-14 weeks of gestation underwent fetal echocardiographic examination at 20-23 weeks. Fifty fetuses with normal NT values were considered as controls. Pulmonary and ...

OBJECTIVE: Small aortic valve replacement remains a challenging hemodynamic problem. A new bioprosthesis (3F Therapeutics, Lake Forest, Calif) was designed to further improve the hemodynamic performance currently achieved with stentless bioprostheses. This valve consists of a tubular structure assembled from 3 equal sections of equine pericardial material, with virtually no ...

BACKGROUND AND AIM OF THE STUDY: Several animal models are currently used to study bioprosthetic tissue calcification. The study aim was to evaluate the influence of species and environmental factors (blood contact and arterial pressure) on valve tissue mineralization. METHODS: Glutaraldehyde-fixed porcine cusps and aortic wall samples were implanted subcutaneously ...

BACKGROUND: In cardiac patients, pulmonary capillary wedge pressure (PCWP) is estimated using color M-mode Doppler study of left ventricular filling and Doppler tissue imaging. The goal of this study was to assess whether echocardiography accurately estimates PCWP in critically ill patients. METHODS: Sixty ventilated patients admitted for septic shock and ...

OBJECTIVE: The aim of this study was to assess the ability of several echocardiographic and tissue Doppler imaging (TDI) derived parameters to improve the noninvasive diagnosis of a pseudonormal mitral inflow pattern. METHODS: Ninety-eight consecutive patients with age-related normal transmitral Doppler profile underwent echocardiography including TDI and measurement of left ...

BACKGROUND: Exposing the developing tissue to flow and pressure in a bioreactor has been shown to enhance tissue formation in tissue-engineered heart valves. Animal studies showed excellent functionality in these valves in the pulmonary position. However, they lack the mechanical strength for implantation in the high-pressure aortic position. Improving the ...

BACKGROUND: The tissue-engineered (TE) heart valve was developed to improve the durability of tissue heart valves. The aim of this study was to evaluate morphological and histological changes in a TE heart valve consisting of decellularized porcine matrices seeded with viable autologous vascular endothelial cells (AVEC). MATERIAL/METHODS: TE valves were ...

PURPOSE: Intraoperative measurement of the aortic valve (AV) gradient in patients undergoing cardiac surgery is routinely performed using transesophageal echocardiography (TEE). In patients with severe aortic stenosis (AS), TEE Doppler beam alignment with the blood flow through the stenotic valve may be inaccurate, resulting in an underestimation of the AV ...

BACKGROUND AND AIMS OF THE STUDY: Cavitation in the mechanical heart valve (MHV) was first detected in Edwards-Duromedics (ED) clinical explants. Early studies indicated that the pitted surface of the valve leaflet was due to cavitation phenomena occurring during valve closing. Cavitation is seen as the transient appearance of bubbles ...

OBJECTIVES: Severe sclerosis of the native aortic annulus can result in a tilted implantation position of mechanical prostheses. In this study, the effects of tilting and rotation on the hemodynamic performance of standard bileaflet valves were assessed in an extracorporeal mock circulatory system. METHODS: A pulsatile mock circulation driven by ...

BACKGROUND: The aim of the study was to determine the relationship between the rate of peak early mitral inflow velocity and the peak early diastolic mitral annular tissue velocities in normal controls and to compare them with subjects with diastolic dysfunction. METHODS: The relationship between early passive diastolic transmitral flow ...

We present a microchip-based, voltage-addressable on/off valve architecture that is fundamentally consistent with the pressures and solvents employed for high-pressure liquid chromatography. Laser photopatterning of polymer monoliths inside glass microchannels is used to fabricate mobile fluid control elements, which are opened and closed by electrokinetic pressures. The glass substrates and ...

An 18-year-old male patient with biventricular hypertrophic obstructive cardiomyopathy (HOCM) had successful reduction of the pressure gradients by cibenzoline. At 11 months after birth, he was first diagnosed with cardiac murmurs and by the age of 5 years, he was diagnosed with subpulmonic infundibular stenosis with a pressure gradient of ...

PURPOSE: Echocardiographic Doppler methods widely used in assessment of the severity of aortic regurgitation (AR) are considered sensitive and reliable. However, they all have limitations for quantitation of AR. The color M-mode Doppler flow propagation velocity (FPV) method has been shown to provide useful insights in the evaluation of left ...

PURPOSE: Congenital aortic valve stenosis is a common problem in pediatric cardiology. The catheter peak to peak systolic gradient is the accepted standard used for prognosis and intervention, but noninvasive correlation in pediatric patients is frequently associated with underestimation or overestimation of this gradient. The purpose of this study was ...

BACKGROUND: The feasibility of hands-free transthoracic continuous determination of pulmonary artery (PA) diastolic pressure (PAD) and cardiac output (CO) by Doppler ultrasound has not been previously demonstrated. We developed a 2.5-MHz spherical transducer mounted in an external housing to permit steering in 360 degrees (Contison). The external housing was attached ...

BACKGROUND: Hydrodynamic performance of a decellularized pulmonary porcine valve was evaluated with a computer versatile pulse duplicator and compared to glutaraldehyde fixated stentless porcine bioprosthesis and a polyurethane heart valve. METHODS: Decellularized pulmonary porcine matrices (Group I, n = 5) were treated chemically to become cell-free collagen matrices. The findings ...

OBJECTIVES: The aim of this study was to determine the accuracy of six noninvasive Doppler methods for assessing invasively derived left ventricular diastolic pressure (LVDP). Background: To date, no studies have evaluated which of the various available Doppler methods are most reliable in determining LVDP in a consecutive patient population ...

The systematic evaluation of different transthoracic echocardiographic (TTE) methods to determine cardiac output (CO) and the effect of changes in intravascular volume on echocardiographically determined indexes of cardiovascular structure in the rat has not been documented. With the use of 11 Wistar rats, simultaneous echocardiographic and thermodilution measurements of CO ...

OBJECTIVE: To evaluate the load dependence of effective regurgitant orifice area (ROA) in an animal model of chronic aortic regurgitation. METHODS: Eight sheep were studied 10-20 weeks after the surgical creation of aortic regurgitation. After baseline studies, 500 ml of blood, angiotensin II, and nitroprusside were infused sequentially. Electromagnetic flow ...

To overcome the limitations of mitral inflow parameters for predicting pulmonary capillary wedge pressure (PCWP), combined indices (with Doppler tissue imaging or color M-mode Doppler) have been developed. This study was aimed to compare the accuracy of these indices to predict PCWP. Sixty-one patients were studied. The best correlations with ...

We tested the performance of low- and medium-pressure PS flow control valves as they were perfused with (1) solutions with varying concentrations of protein, (2) solutions with varying numbers of red blood cells (RBC) or (3) solutions with varying concentrations of whole blood. Perfusion was performed with a peristaltic pump ...

Previous in vitro testing (mainly in aortic position) and clinical experience (often based on Doppler echocardiographic observations) demonstrated an excellent hemodynamic behavior of the On-X valve. However, integrative studies including simultaneous hemodynamic pressure and flow measurements and Doppler echocardiography are lacking. Using our computer-controlled mock loop system, two samples of ...

OBJECTIVES: We sought to investigate the mechanisms of left ventricular (LV) intracavitary early diastolic flow during changes in contractility and loading. BACKGROUND: There is limited understanding of how intracavitary flow velocities relate to intraventricular driving pressures. METHODS: In 12 anesthetized dogs, we measured pressures in the left atrium (LA), LV ...

BACKGROUND AND AIM OF THE STUDY: The edge-to-edge technique is used to restore valvular competence in mitral insufficiency. The efficacy of the method is under debate due to the potential for creating functional mitral stenosis. An exercise echocardiographic study was carried out to investigate valve function and hemodynamics in patients ...

The goals of this study were to characterize normal patterns of longitudinal motion of atrioventricular annuli in the young, establish reference values and assess growth-related changes (n = 40). Sensitivity to changes in right ventricular volume and pressure load was assessed in patients with atrial septal defect (ASD) (n = ...

Pollution by anesthetic gases can be a problem in operating theaters. More than 90 per cent of this pollution can be reduced by using a scavenging system. Such systems increase the complexity, and thus the hazards of administering anesthesia. A case of pneumothorax prompted an investigation of the active scavenging ...

BACKGROUND: We tested the flow characteristics of a new siphon-reducing device, the Shunt Assistant Valve trade mark (SAV) combined with a Codman-Hakim trade mark (CH) programmable valve and studied 4 clinical cases. We discussed the efficacy of the SAV at preventing low pressure syndrome secondary to overdrainage. MATERIALS AND METHODS: ...

We built a high-speed, pneumatic pressure clamp to stimulate patch-clamped membranes mechanically. The key control element is a newly designed differential valve that uses a single, nickel-plated piezoelectric bending element to control both pressure and vacuum. To minimize response time, the valve body was designed with minimum dead volume. The ...

The aim of this study was to perform combined hydrodynamic and Doppler echocardiographic tests of the Omnicarbon 21 mm cardiac valve in aortic position in our Pulse Duplicator System for simultaneous assessment of valve performance and valve leakage data. During forward flow conditions, measured mean pressure gradients are between 4.5 ...

BACKGROUND: The aim of this study was to evaluate the changes in mitral valve area and mean transmitral pressure gradient before and after percutaneous balloon mitral valvotomy and at 2 years of follow-up. We hypothesized that the patient's age would be an important determinant for the success of balloon valvotomy. ...

A computational fluid dynamics model for the analysis of the bileaflet mechanical heart valve closure process is presented. The objective of the study is to demonstrate the ability of the numerical model to simulate the leaflet motion during the closing phase in order to investigate the closure fluid dynamics and ...

BACKGROUND: The hydrodynamic function of the smaller size Mitroflow Synergy stented pericardial bioprostheses has been studied in an in vitro fresh tissue aortic root model and compared with previous studies of free-sewn bioprostheses. METHODS: Three valves of each of the sizes 19, 21, and 23 mm were sutured into fresh ...

BACKGROUND AND AIM OF THE STUDY: Because the hemodynamic basis of aortic valve area (AVA) has never been validated in vivo, several alternative indices have been proposed to quantify the severity of aortic stenosis (AS). This study was designed to assess the fluid-dynamics of aortic valve stenosis in order to ...

Manual hyperinflation (MHI) is used by physiotherapists as a treatment technique in intubated patients. This study investigated the effect of three different MHI techniques using a Mapleson-C circuit configuration with a CIG Medishield valve on volume delivered (Vt), peak inspiratory (PIFR) and expiratory flow rates (PEFR), and peak airway pressure ...

Zero transvalvular pressure fixation is thought to improve porcine bioprosthetic heart valve (BHV) durability by preserving the collagen fiber architecture of the native tissue, and thereby native mechanical properties. However, it is not known if the native mechanical properties are stable during long-term valve operation and thus provide additional durability. ...

Patients with mitral stenosis have usually blunted pulmonary venous (PV) flow, because of decreased mitral valve area and diastolic dysfunction. The authors compared changes in Doppler PV velocities by using transesophageal echocardiography (TEE) against hemodynamics parameters before and after mitral balloon valvotomy to observe relevance of PV velocities and endsystolic ...

PURPOSE: One-third of patients who suffer from idiopathic fecal incontinence are found to have maximum mean resting pressures within the normal range. The objective of this study was to determine whether measuring the gradient of pressure at rest throughout the anal canal is a more sensitive predictor of incontinence in ...

Modifications in diastolic function occur in a broad range of cardiovascular diseases and there is an increasing evidence that abnormalities in left ventricular function may contribute significantly to the symptomatology. The flow inside the left ventricle during the diastole is here investigated by numerical solution of the Navier-Stokes equations under ...

INTRODUCTION: The internal jugular vein valve (IJVV), which is situated just above the termination of the internal jugular vein, is the only valve between the heart and the brain. This means that it plays a role in the prevention of cephalad flow of venous blood. If the IJVV is damaged ...

BACKGROUND: Postoperative neurologic complications in cardiac surgery patients are considered to be associated with the design of an aortic cannula and its hydrodynamic profile. To gain knowledge about the hydrodynamics of a new cannula type, based on the integration of a helical stator in its tip, was the aim of ...

We performed an experimental and clinical evaluation of a new low-profile bileaflet aortic valve (Regent, St. Jude Medical Inc., St. Paul, MN, U.S.A.). Common valve sizes were experimentally tested for leakage volume, pressure drop, and transvalvular hemodynamics using a pulse duplicator. Thirty patients (mean age 60 +/- 7 years, predominant ...

IMPLICATIONS: We describe a case in which intraoperative echocardiography recorded an abnormally high pressure gradient across a newly implanted mechanical heart valve. However, inserting pressure-transducing needles on each side of this prosthesis did not confirm the echocardiographic findings. The prosthesis was later confirmed to be malfunctioning and was replaced.

In order to determine the optimal valve pressure setting during the first weeks in neonates after implantation of programmable Hakim valves and to analyze the benefits and possible side effects of a new treatment protocol in this age group, we performed this prospective study. In 20 consecutive newborns less than ...

Mitral regurgitation (MR) creates a unique hemodynamic stress by inducing a low pressure form of volume overload due to ejection into the left atrium, without the pressure component that accompanies aortic regurgitation. Chronic therapy with vasodilators has been shown to reduce left ventricular wall stress, and thereby delay or obviate ...

OBJECTIVE: The difficulty in tying multiple knots with endoscopic instruments constitutes a technical obstacle to the development of closed-chest valve surgery. The following set of experiments was undertaken to ascertain the in-vivo feasibility of using an intracardiac ultrasonic welding device for knotless suture fixation during mitral valve replacement (MVR). METHODS: ...

OBJECTIVES: In normal pressure hydrocephalus, there is no clear evidence that the opening pressure of differential pressure valves influences outcome. In this study, the objective was to determine whether the relationship between valve opening pressure and post-operative postural ICP changes was predictable. METHODS: Eight adult-onset hydrocephalus patients were evaluated using ...