In a premature ventricular contraction (PVC), a systolic blood pressure peak is missing during the affected cardiac cycle, leading to a prolonged reduction in blood pressure which is then followed by a large burst of sympathetic outflow. In a normal ventricular contraction, it is generally believed that peak carotid and ...

BACKGROUND: Patellofemoral joint pain is a common knee disorder, but its underlying causes remain unknown. One proposed mechanism is an imbalance in force in the knee extensor muscles. Specifically, the vastus medialis and vastus lateralis are thought to play a crucial role in proper patellar tracking, and weakness in vastus ...

This review discusses cardiac consequences of pressure overload. In response to elevated pressure, the ventricular hypertrophy compensates for the increased wall stress. However, the ventricular hypertrophy involves numerous structural adaptations that may lead to ventricular dysfunction and, eventually, heart failure. Particular emphasis is placed on molecular mechanisms that govern the ...

A 9-year-old girl had hypertension (systolic blood pressure of 125 mm Hg) noted at an annual well child visit. An ultrasound study demonstrated a large right renal cystic mass. A partial nephrectomy was performed. The surgical specimen was 9.7 × 9.4 × 6.4 cm and weighed 413.2 g. The tumor ...

In the two-cell stage embryos of Caenorhabditis elegans, the contact surface of the two blastomeres forms a curve that bulges from the AB blastomere to the P(1) blastomere. This curve is a consequence of the high intracellular hydrostatic pressure of AB compared with that of P(1). However, the higher pressure ...

Central venous pressure (CVP), an estimate of right atrial pressure, has been used to assess cardiac preload and volume status in critically ill patients, assist in the diagnosis of right-sided heart failure, and guide fluid resuscitation. It is determined by the interaction between cardiac function and venous return. CVP measurements ...

Background. Potassium is the main intracellular cation, which contributes to keeping the intracellular membrane potential slightly negative and elicits contraction of smooth, skeletal and cardiac muscle. A change in potassium intake modifies both cardiovascular and renal tubular function. The purpose of the trial was to investigate the effect of dietary ...

Abstract  We present a case of acute respiratory insufficiency with right-to-left atrial shunting under normal intracardiac pressures discovered several days after aortic surgery for aortic dissection. We discuss the possible mechanisms and management of right-to-left atrial shunting through an atrial septum defect with normal intracardiac pressures following cardiac surgery. (J ...

BACKGROUND: In vitro studies suggest that phosphorylation of titin reduces myocyte/myofiber stiffness. Titin can be phosphorylated by cGMP-activated protein kinase. Intracellular cGMP production is stimulated by B-type natriuretic peptide (BNP) and degraded by phosphodiesterases, including phosphodiesterase-5A. We hypothesized that a phosphodiesterase-5A inhibitor (sildenafil) alone or in combination with BNP would ...

In hearts of higher invertebrates as well as vertebrates, the work performed by the ventricle is a function of both rate and contractility. Decapod crustaceans experience a hypoxia-induced bradycardia that is thought to result in an overall reduction in cardiac work; however, this hypothesis has not yet been tested and ...

Tissue-mimicking materials (TMMs) can provide a convenient, stable, and reproducible means for testing high intensity focused ultrasound (HIFU) devices. When TMMs containing thermal sensors are used to measure ultrasound-induced temperature rise, it is important that measurement results reasonably represent those that occur in biological tissue. Therefore the aim of this ...

Assessment of spontaneous slow waves in the peripheral blood volume using the photoplethysmogram (PPG) has shown potential clinical value, but the physiological correlates of these fluctuations have not been fully elucidated. This study addressed the contribution of arterial pressure and muscle sympathetic nerve activity (MSNA) in beat-to-beat PPG variability (PPGV) ...

This study aimed to apply novel high resolution manometry with eight-sector radial pressure resolution (3D-HRM technology) to resolve the deglutitive pressure morphology at the esophagogastric junction (EGJ) before, during, and after bolus transit. Methods: A hybrid HRM assembly including a 9-cm long 3D-HRM array was used to record EGJ pressure ...

This study determined whether an elevated muscle metaboreflex contributes to the excessive blood pressure response to exercise in postmenopausal women. Thirty healthy female volunteers were studied (15 postmenopausal and 15 premenopausal). Stroke volume, heart rate, cardiac output (CO), systolic blood pressure, diastolic blood pressure, and total vascular conductance (TVC) were ...

ABSTRACT: This experimental animal study investigates the effects of combined recombinant human activated protein C (rhAPC) and ceftazidime on cardio-pulmonary function in acute lung injury and severe sepsis. Twenty-one sheep (37±2 kg) were operatively prepared and randomly allocated to either the sham, control, or treatment group (n=7 each). Single treatments ...

Formation of a dense microtubule network that impedes cardiac contraction and intracellular transport occurs in severe pressure overload hypertrophy. This process is highly dynamic, since microtubule depolymerization causes striking improvement in contractile function. A molecular etiology for this cytoskeletal alteration has been defined in terms of type 1 and type ...

We assessed the timing of vagal and sympathetic factors that mediate hypotension during CSM (carotid sinus massage) in patients with carotid sinus hypersensitivity. We hypothesized that a fall in cardiac output would precede vasodepression, and that vasodepression would be exaggerated by head-up tilt. We performed pulse contour analyses on blood ...

Rationale:One of the physiological mechanisms by which the heart adapts to a rise in blood pressure is by augmenting myocyte stretch-mediated intracellular calcium, with a subsequent increase in contractility. This slow force response was first described over a century ago and has long been considered compensatory, but its underlying mechanisms ...

AIMS: This study evaluated the hypothesis that exogenous nitric oxide (NO) supplementation during acute hemodilution with plasma expander (PE) provides beneficial effects on cardiac function. MAIN METHODS: Acute hemodilution in golden Syrian hamsters was induced by a 40% of blood volume exchange with dextran 70kDa. Intravascular NO supplementation after hemodilution ...

AIMS: Right ventricular (RV) dysfunction is a major determinant of long-term morbidity and mortality in congenital heart disease. The right ventricle (RV) is genetically different from the left ventricle (LV), but it is unknown as to whether this has consequences for the cellular responses to abnormal loading conditions. In the ...

AIM: The objective of the study was to evaluate the impact of the cardiac cycle on ultrasound measurements of abdominal aortic aneurysm (AAA) diameters. METHODS: In total, 603 AAAs detected by screening were investigated with respect to the maximal systolic and diastolic anterior-posterior aortic diameters during the cardiac cycle using ...

A theoretical model is used to simulate the dynamics of the left ventricle (LV) through all phases of the cardiac cycle, including interactions between myocardial contractility and ventricular pressure generation and effects of preload and afterload. The ventricle is represented as a cylinder containing helical muscle fibres with non-linear passive ...

This study tested the hypothesis that acute isocapnic hypoxia results in persistent resetting of the baroreflex to higher levels of muscle sympathetic nerve activity (MSNA), which outlasts the hypoxic stimulus. Cardiorespiratory measures were recorded in humans (26 ± 1 yrs; n = 14; 3 female) during baseline, exposure to 20 ...

BACKGROUND: Knowledge of cardiac filling pressures is critical in the diagnosis and management of patients with dyspnea or heart failure. Echocardiography and B-natriuretic peptide (BNP) testing are commonly used to estimate these pressures, but their incremental value beyond physical examination remains unknown. METHODS: Right and left heart filling pressures were ...

The spectral power of low frequency oscillations of systolic arterial pressure (SAP(LF)) has been used as a non-invasive surrogate of muscle sympathetic nerve activity (MSNA) in both experimental and clinical situations. For SAP(LF) to be used in this way, a relationship must exist between SAP(LF) and MSNA within individuals during ...

Background  High resolution manometry (HRM) has demonstrated two distinct smooth muscle contraction segments in the esophageal body; changes in these segments typify certain esophageal disorders. We investigated segmental characteristics in subgroups of non-cardiac chest pain (NCCP). Methods  32 NCCP subjects were segregated into a GERD group (ambulatory pH testing off ...

ABSTRACT: Activation of renin-angiotensin system has been linked to cardiovascular and autonomic dysfunctions in diabetes. Experiments were performed to investigate the effects of angiotensin-converting enzyme inhibitor Enalapril (ACEI) on cardiac and autonomic functions in diabetic rats. Diabetes was induced by streptozotocin (50 mg/kg), and rats were treated with Enalapril (1 ...

The neural interaction between the cardiopulmonary and arterial baroreflex may be critical for the regulation of blood pressure during orthostatic stress. However, studies have reported conflicting results with some indicating increases and others decreases in cardiac baroreflex sensitivity (i.e., gain) with cardiopulmonary unloading. Thus, the effect of orthostatic stress induced-central ...

There is evidence that in cardiac failure there is defective baroreceptor reflex control of sympathetic nerve activity. Often, cardiac failure is preceded by a state of cardiac hypertrophy where there may be enhanced performance of the heart. This study investigated whether in two different models of cardiac hypertrophy there was ...

The α2 isoform of the Na, K-ATPase (α2) is thought to play a role in blood pressure regulation, but the specific cell type(s) involved have not been identified. Therefore, it is important to study the role of the α2 in individual cell types in the cardiovascular system. The present study ...

The cause(s) of initial orthostatic hypotension (transient fall in blood pressure within 15 s upon active rising) have not been established. We tested the hypothesis that this hypotension is due to local vascular phenomena in contracting leg muscles from the brief effort of standing up. Seventeen young healthy subjects (2 ...

In mammals, natriuretic peptides (NPs) lower blood pressure, reduce blood volume and broadly inhibit cardiovascular remodeling. NPs are often referred to as cardiac hormones, though they also have integral roles in regulating vascular tone, endothelial remodeling and inhibiting vascular smooth muscle cell hypertrophy. Two NPs [atrial (ANP) and C-type (CNP)] ...

Fetal cardiac intervention for critical aortic stenosis (AS) with evolving hypoplastic left heart syndrome is performed in an attempt to maintain a biventricular circulation postnatally. The procedure has been hindered by technical challenges and poor candidate selection. We report here the novel use of a pressure guidewire during aortic valvuloplasty ...

Measurement of the energy consumption of isolated cardiac trabeculae requires highly sensitive temperature sensors. In this paper we describe and characterize an initial prototype of a vapor pressure thermometer being designed and built for application to muscle microcalorimetry. The device exploits the change in vapor pressure with temperature of a ...

In this paper Heart Rate Variability (HRV) and Blood Pressure Variability (BPV) were analyzed before the onset of cardiac arrhythmia in order to derive markers for short-term forecasting. The (a) coherence between systolic blood pressure (SBP) and cardiac oscillations in low-frequency (LF) and high-frequency (HF) band; (b) fluctuations of phase; ...

Calpains make up a family of Ca(2+)-dependent intracellular cysteine proteases, that include ubiquitously expressed μ- and m-calpains. Both are heterodimers consisting of a distinct large catalytic subunit (calpain 1 for μ-calpain and calpain 2 for m-calpain) and a common regulatory subunit, calpain 4. The physiological roles of calpain remain unclear ...

OBJECTIVE: Increasing evidence shows that some cardiac defects may benefit from fetal interventions, including fetal cardiac surgery. We attempted to develop an in vivo animal model of fetal cardiopulmonary bypass with cardioplegic arrest. METHODS: Operations were performed on 14 pregnant goats. The extracorporeal circulation circuit consisted of a centrifugal pump, silicone ...

We examined a novel therapeutic approach for hypertension, a small molecule direct inhibitor of smooth muscle myosin, CK-2018448, in conscious dogs with renal hypertension and compared its efficacy with that of a calcium channel blocker, amlodipine. Dogs were instrumented with a miniature left ventricular pressure gauge, an aortic pressure catheter, ...

Rationale: Induction of the fetal hypertrophic marker gene β-myosin heavy chain (β-MyHC) is a signature feature of pressure overload hypertrophy in rodents. β-MyHC is assumed present in all or most enlarged myocytes. Objective: To quantify the number and size of myocytes expressing endogenous β-MyHC by a flow cytometry approach. Methods ...

OBJECTIVE: Most cardiac preservation solutions provide safe cold ischemic storage times for 4 to 5 hours. Our aim was to investigate the effects of 8 hours of cold static storage (4°C) using 2 normokalemic, polarizing adenosine-lidocaine (Adenocaine; Hibernation Therapeutics Global Ltd, Kilquade, Ireland) solutions and to compare their functional recovery ...

ABSTRACT: Objectives Right ventricular heart rupture is a devastating complication associated with negative pressure wound therapy (NPWT) in cardiac surgery. The use of a rigid barrier has been suggested to offer protection against this lethal complication, by preventing the heart from being drawn up and damaged by the sharp edges ...

Previous studies indicate that superoxide is important in the modulation of blood pressure but have not specifically identified the cell types or organs involved. We created mice with loxP sites flanking the extracellular superoxide dismutase (SOD3) gene. These mice were crossed with mice expressing inducible Cre-recombinase driven by the smooth ...

We report the failure of an i-gel and an Ambu AuraOnce supraglottic airway to ventilate a drowning victim. Failure was attributed to changes in lung physiology following submersion and inhalation of water that may have required ventilation pressures up to 40 cmH2O to treat the victim's hypoxaemia. The ease of ...

PURPOSE:: The purpose of this study was to describe resting cardiopulmonary function in highlytrained athletes with cervical spinal cord injury (SCI), and to compare the data with able-bodied (AB) control subjects. METHODS:: Twelve Paralympic wheelchair rugby players with cervical SCI (injury level, C5-C7) and 12 AB controls matched for age, ...

PURPOSE OF REVIEW: To re-emphasize the epidemiology, pathophysiology, diagnosis, and treatment of cardiac tamponade. RECENT FINDINGS: Cardiac tamponade is a cause of obstructive shock. Incidence of cardiac tamponade is poorly documented. In cardiac tamponade, the pericardial pressure may reach 15-20 mmHg, leading to an equalization of pressures into the cardiac chambers ...

Increased cardiovascular risk after mercury exposure has been described but cardiac effects resulting from controlled chronic treatment are not yet well explored. We analyzed the effects of chronic exposure to low mercury concentrations on hemodynamic and ventricular function of isolated hearts. Wistar rats were treated with HgCl(2) (1st dose 4.6μg/kg, ...

Based on observations that as cardiac output (as determined by an artificial pump) was experimentally increased the right atrial pressure decreased, Arthur Guyton and coworkers proposed an interpretation that right atrial pressure represents a back pressure restricting venous return (equal to cardiac output in steady state). The idea that right ...

Background and purpose:  Reduced cardiac contractility has been associated with disrupted myocardial Ca(2+) signaling. The drug K201 acts on a number of Ca(2+) handling proteins and in vivo improves cardiac contractility in a variety of animal models of myocardial dysfunction. However, it is unclear whether (i) this is dependent on ...

A neonate initially presented with heart failure, with severe cardiac dysfunction confirmed by echocardiography, at 3 days of age. Blood pressure at presentation was in the high normal range. It was not until there was a rapid improvement of left-ventricular function on intravenous milrinone that the infant was noted to be ...

Paracrine growth factor-mediated crosstalk between cardiac myocytes and nonmyocytes in the heart is critical for programming adaptive cardiac hypertrophy in which myocyte size, capillary density, and the extracellular matrix function coordinately. To examine the role that placental growth factor (PGF) plays in the heart as a paracrine regulator of cardiac ...