scholarly journals The mechanism of intracardiac shunting in the lizard Varanus exanthematicus

1983 ◽  
Vol 105 (1) ◽  
pp. 15-31 ◽  
Author(s):  
N. Heisler ◽  
P. Neumann ◽  
G. M. Maloiy
Keyword(s):  
Cardiac Cycle ◽  
Systolic Pressure ◽  
Lung Ventilation ◽  
Systemic Circulation ◽  
Half Cycle ◽  
Pressure Measurements ◽  
Anatomical Studies ◽  
The Right ◽  
Intracardiac Pressure ◽  
Intracardiac Shunting

Intracardiac shunting was studied in unanaesthetized and unrestrained specimens of Varanus exanthematicus by simultaneous injection of radioactively labelled microspheres (15 micron) into the right and left atria. Lung ventilation was monitored by intratracheal pneumotachography. It was found that intracardiac shunting was not significantly affected by the spontaneously occurring periods of ventilation and apnoea: the right-to-left shunt averaged 29 and 31%, respectively, and the left-to-right shunt was 11% in both conditions. The observed shunting, although rather constant with time and independent of the ventilatory state, varied in different individuals. Anatomical studies and intracardiac pressure measurements revealed that, in spite of crocodilian-like systolic pressure separation between pulmonary and systemic circulation (based on the muscular ridge, ‘Muskelleiste’, between cavum venosum and cavum pulmonale), the cavum venosum is shared by both the pulmonary and the systemic circulation. Intracardiac shunting appears to be mainly due to wash-out of the cavum venosum: blood remaining in this chamber at the end of systole (oxygenated) or at the end of diastole (deoxygenated) is washed into the respective ‘inadequate’ vascular bed during the next half-cycle of heart action. Thus the extent of intracardiac shunting is expected to depend primarily on the volume and the changes in volume of the cavum venosum during the cardiac cycle.

Activity of in vivo canine cardiac plexus neurons

1988 ◽  
Vol 255 (4) ◽  
pp. H789-H800 ◽  
Author(s):  
M. Gagliardi ◽  
W. C. Randall ◽  
D. Bieger ◽  
R. D. Wurster ◽  
D. A. Hopkins ◽  
...  
Keyword(s):  
Cardiac Cycle ◽  
Pulmonary Veins ◽  
Systolic Pressure ◽  
Identified Neurons ◽  
Fat Pad ◽  
Respiratory Dynamics ◽  
The Right ◽  
Ganglion Neurons ◽  
Ganglionated Plexus

The activity of 394 spontaneously active neurons located in the ganglionated plexus of the ventral epicardial fat pad overlying the right atrium and pulmonary veins was recorded. Ganglia that contained various numbers of neurons, many with two or more nucleoli, were identified adjacent to the recording sites. Spontaneous activity was correlated with the cardiac cycle in 39% and with the respiratory cycle in 8% of the identified neurons. Neuronal activity occurred in specific phases of the cardiac cycle when arterial pressure was between approximately 70 and 175 mmHg. During increases in systolic pressure induced by positive inotropic agents or aortic occlusion, responses of neurons that displayed cardiovascular-related activity were enhanced. These responses persisted after acute decentralization. The activity of 14% of all identified neurons was altered when discrete regions of the heart, great thoracic vessels, or lungs were mechanically distorted by gentle touch. Trains of stimuli, but not single stimuli, delivered to the vagosympathetic complexes, stellate ganglia, or cardiopulmonary nerves activated ganglionic neurons in intact or acutely decentralized preparations. It is concluded that the activity of some cardiac ganglion neurons is related to cardiovascular or respiratory dynamics and that some of these neurons receive inputs from sympathetic and parasympathetic efferent axons as well as from cardiac mechanoreceptors.

scholarly journals Right ventricular function and its coupling with the pulmonary circulation in acute heart failure

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Barki ◽  
M Losito ◽  
M.M Caracciolo ◽  
F Bandera ◽  
M Rovida ◽  
...  
Keyword(s):  
Heart Failure ◽  
Acute Heart Failure ◽  
Acute Phase ◽  
Pulmonary Circulation ◽  
Heart Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Response To Treatment ◽  
The Right ◽  
B Lines

Abstract Background The right ventricle (RV) is extremely sensitive to hemodynamic changes and increased impedance. In acute heart failure (AHF), the development of pulmonary venous congestion and the increase of left ventricular (LV) filling pressures favors pulmonary vascular adverse remodeling and ultimately RV dysfunction, leading to the onset of symptoms and to a further decay of cardiac dynamics. Purpose The aim of the study was to evaluate RV morphology and functional dynamics at admission and discharge in patients hospitalized for AHF, analyzing the role and the response to treatment of the RV and its coupling with pulmonary circulation (PC). Methods Eighty-one AHF patients (mean age 75.75±10.6 years, 59% males) were prospectively enrolled within 24–48 hours from admission to the emergency department (ED). In either the acute phase and at pre-discharge all patients underwent M-Mode, 2-Dimensional and Doppler transthoracic echocardiography (TTE), as well as lung ultrasonography (LUS), to detect an increase of extravascular lung water (EVLW) and development of pleural effusion. Laboratory tests were performed in the acute phase and at pre-discharge including the evaluation of NT-proBNP. Results At baseline we observed a high prevalence of RV dysfunction as documented by a reduced RV systolic longitudinal function [mean tricuspid annular plane systolic excursion (TAPSE) at admission of 16.47±3.86 mm with 50% of the patients exhibiting a TAPSE<16mm], a decreased DTI-derived tricuspid lateral annular systolic velocity (50% of the subjects showed a tricuspid s' wave<10 cm/s) and a reduced RV fractional area change (mean FAC at admission of 36.4±14.6%). Furthermore, an increased pulmonary arterial systolic pressure (PASP) and a severe impairment in terms of RV coupling to PC was detected at initial evaluation (mean PASP at admission: 38.8±10.8 mmHg; average TAPSE/PASP at admission: 0.45±0.17 mm/mmHg). At pre-discharge a significant increment of TAPSE (16.47±3.86 mm vs. 17.45±3.88; p=0.05) and a reduction of PASP (38.8±10.8 mmHg vs. 30.5±9.6mmHg, p<0.001) was observed. Furthermore, in the whole population we assisted to a significant improvement in terms of RV function and its coupling with PC as demonstrated by the significant increase of TAPSE/PASP ratio (TAPSE/PASP: 0.45±0.17 mm/mmHg vs 0.62±0.20 mm/mmHg; p<0.001). Patients significantly reduced from admission to discharge the number of B-lines and NT-proBNP (B-lines: 22.2±17.1 vs. 6.5±5 p<0.001; NT-proBNP: 8738±948 ng/l vs 4227±659 ng/l p<0.001) (Figure 1). Nonetheless, no significant changes of left atrial and left ventricular dimensions and function were noted. Conclusions In AHF, development of congestion and EVLW significantly impact on the right heart function. Decongestion therapy is effective for restoring acute reversal of RV dysfunction, but the question remains on how to impact on the biological properties of the RV. Funding Acknowledgement Type of funding source: None

Dynamics of the right atrio-ventricular junction in human: a spatial high-resolution study with multiphase computed tomography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
J Jouan ◽  
I Masari ◽  
V Bliah ◽  
G Soulat ◽  
D Craiem ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cardiac Cycle ◽  
Cardiac Computed Tomography ◽  
Reconstruction Method ◽  
Imaging Data ◽  
High Definition ◽  
Vertical Projection ◽  
Horizontal Projection ◽  
Cross Sectional ◽  
The Right

Abstract Introduction In order to improve knowledge of the tricuspid valve (TV) function and its coupling with the right atrio-ventricular junction (RAVJ) and right ventricle (RV), new four-dimensional high-definition imagery methods are mandatory (3D+t). Purpose Using an innovative reconstruction method based on multiphase cardiac computed tomography imaging (4D-MCCTI), we finely analyzed the morphological & dynamical features of tricuspid annulus (TA) and RAVJ components in order to assess new functional parameters of TV and RV functions. Methods Volume imaging data sets through time were obtained from 4D-MCCTI of 30 subjects (sex ratio 1, mean age 57±11y.) with no rhythm, valvular or ventricular abnormalities on echocardiography and implemented in a custom software for 3D semi-automated delineation of 18 points around TA perimeter. Coordinates of these points in each of the 10 time-phases within an RR interval were used to calculate specific geometrical features of TA such as 3D/2D areas, perimeters, 360°-diameters and vertical deformation. Subsequently, RV and Right Atrium (RA) inner contours were also delineated (Figure). Results TA shape was elliptical in horizontal projection with a mean eccentricity index (EcI) of 0.58±0.12; and saddle-shapped in vertical projection with a horn nearby the antero-septal commissure. This feature remained throughout the cardiac cycle but TA was more planar (minimal TA-height: 4.47±1.04 mm) and circular (minimal EcI=0.44±0.14) in mid-diastole when TA-3Darea and TA-3Dperimeter reached a maximum of 6.98±1.21 cm2/m2 and 7.41±0.91 cm, respectively. Correlation between TA-3Darea, TA-2Darea and latero-septal diameter (LSD) were R2=0.99 and R2=0.73, respectively. LSD was minimal in early-systole (18.83±3.04 mm/m2) and maximal in mid-diastole (20.04±3.05 mm/m2). Correlation of TA-3Darea with RV and RA cross-sectional areas were R2=0.82 and R2=0.71, respectively. Conversely, there was no significant correlation between TA, RV and RA concentric contractions. Conclusions Our method for 4D-MTCCI analysis has allowed confirming the shape and dynamics function of RAVJ throughout the cardiac cycle in healthy subjects, and giving new reference parameters for TV and RV evaluation. Software multiplanar view of TA Funding Acknowledgement Type of funding source: None

The “Spacemaker”, a New Device for Minimally Invasive Cardiothoracic Surgery: An Evaluation and Feasibility Study

2015 ◽  
Vol 10 (4) ◽  
pp. 241-247
Author(s):  
Pieter W.J. Lozekoot ◽  
Sandro Gelsomino ◽  
Paul B. Kwant ◽  
Orlando Parise ◽  
Francesco Matteucci ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Surgical Procedures ◽  
Lung Tissue ◽  
Lung Ventilation ◽  
Cardiothoracic Surgery ◽  
Respiratory Compromise ◽  
One Lung Ventilation ◽  
New Device ◽  
Lead Placement ◽  
The Right

Objective Our aim was to evaluate a new inflatable lung retractor, the “Spacemaker”, and its efficacy in facilitating minimally invasive cardiothoracic surgery without the need of one lung ventilation or carbon dioxide overpressure insufflation. Methods The device was tested in 12 anesthetized pigs (90–100 kg) placed on standard endotracheal ventilation. The device was introduced into the right or left side of the chest, depending on the intended procedure to be performed, via a 3-cm incision in the fifth intercostal space. A total of seven animals were used to evaluate hemodynamic and respiratory response to the device, whereas another five animals were used to assess the feasibility of a variety of minimally invasive cardiothoracic surgical procedures. Results Introduction was easy and unhindered. The device was inflated up to 0.6 bar, thereby pushing the lung tissue gently away cranially, posteriorly, and caudally without interfering with pulmonary function or resulting in respiratory compromise. In addition, hemodynamics remained stable throughout the experiments. Different closed-chest surgical procedures such as left atrial appendage exclusion, pulmonary vein exposure, pacemaker lead placement, and endoscopic stabilization for coronary surgery, were successfully performed. Removal was quick and complete in all cases, and lung tissue showed no remnant atelectasis. Conclusions The “Spacemaker” may represent a reliable alternative to current conventional techniques to facilitate minimally invasive cardiothoracic surgery. Further research is warranted to confirm the effectiveness and the safety of this device and to optimize the model before its use in humans and its introduction into clinical practice.

Abstract 15388: Persistent Pulmonary Hypertension After Transcatheter Aortic Valve Implantation: Impact on Mortality

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Maria Drakopoulou ◽  
Konstantinos Stathogiannis ◽  
Konstantinos Toutouzas ◽  
George Latsios ◽  
Andreas Synetos ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Aortic Stenosis ◽  
Pulmonary Artery ◽  
Severe Aortic Stenosis ◽  
Systolic Pressure ◽  
Right Atrial ◽  
Pulmonary Artery Systolic Pressure ◽  
End Point ◽  
The Right ◽  
The Impact

Objective: Severe aortic stenosis leads to increased pulmonary arterial systolic pressure. A controversy still remains regarding the impact of persistent pulmonary hypertension (PHT) on prognosis of patients undergoing transcatheter aortic valve implantation (TAVI). We sought to investigate the impact of persistent PHT on 2-year all-cause mortality of patients with severe aortic stenosis following TAVI. Methods: Patients with severe and symptomatic aortic stenosis (effective orifice area [EOA]≤1 cm 2 ) who were scheduled for TAVI with a self-expanding valve at our institution were prospectively enrolled. Prospectively collected echocardiographic data before and after TAVI were retrospectively analyzed in all patients. Pulmonary artery systolic pressure was estimated as the sum of the right ventricular to the right atrial gradient during systole and the right atrial pressure. PHT following TAVI was classified as absent if <35 mmHg and persistent if ≥35 mmHg. Primary clinical end-point was 2-year all-cause mortality defined according to the criteria proposed by the Valve Academic Research Consortium-2. Results: Hundred and forty patients (mean age: 82±9 years) were included in the study. The primary clinical end point occurred in 17 patients (12%) during a median follow-up period of 2 years. Mean pulmonary artery systolic pressure was reduced in all patients following TAVI (45±9 versus 41±6 mmHg, p<0.01). Mortality rate was higher in patients with persistent PHT compared to patients with normal pulmonary artery systolic pressure following TAVI (26% versus 14 %, p<0.01). Patients that reached the primary clinical end point had a higher post procedural mean systolic pulmonary pressure (43±9 versus 39±6 mmHg, p=0.02). In multivariate regression analysis, persistence of PHT (OR: 2.51, 95% CI: 1.109-7.224, p=0.01) was an independent predictor of long-term mortality. Conclusions: The persistence of pulmonary hypertension after TAVI is associated with long term mortality. Identifying the population that will clearly benefit from TAVI is still need to be validated by larger trials.

Abstract 1122‐000232: The Importance of Performing Venous Pressure Measurements Following Venous Sinus Stenting for Idiopathic Intracranial Hypertension

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Yazan Radaideh
Keyword(s):  
Pressure Gradient ◽  
Intracranial Hypertension ◽  
Stent Placement ◽  
Idiopathic Intracranial Hypertension ◽  
Venous Pressure ◽  
Sigmoid Sinus ◽  
Venous Sinus ◽  
Pressure Measurements ◽  
Sinus Stenosis ◽  
The Right

Introduction : Although venous sinus stenting is an established treatment for medically refractory idiopathic intracranial hypertension, a subset of patients shows little or no improvement of symptoms after stenting. While this could be related to a number of factors, failure to sufficiently address the pressure gradient is one that can be recognized during the treatment procedure. We describe two patients who had a persistent venous pressure gradient after stent placement. Once identified, a second stent was placed with subsequent resolution of the pressure gradient. Methods : This retrospective chart review identified patients at a single institution who underwent venous sinus stenting and required immediate placement of a second venous sinus stent for a persistent pressure gradient. Results : Two patients with refractory idiopathic intracranial hypertension underwent cerebral angiography with venous manometry. In the first patient, unilateral venous sinus stenosis was present with a maximum pressure of 50 mmHg, which only decreased to 30 mmHg after placement of a right transverse‐sigmoid sinus stent. Subsequent manometry revealed a persistent gradient between the superior sagittal sinus and the right transverse sinus, which resolved after placement of a second stent in this location. In the second patient, bilateral stenosis was observed at the transverse‐sigmoid sinus junction; the maximum venous pressure was 40 mmHg, and a gradient of 30 mmHg was measured at the right transverse‐sigmoid junction, where a venous sinus stent was placed. Venous sinus pressure measurements performed immediately after the stent placement demonstrated a persistent pressure gradient of 20 mmHg in the contralateral transverse‐sigmoid sinus junction, which resolved after contralateral stent placement. Both patients showed sustained improvement in their symptoms at 1 year follow up. Conclusions : In some patients with idiopathic intracranial hypertension and venous sinus stenosis, a single stent may not sufficiently reduce the pressure gradient. A second stent may be required; however, this is only detectable with post‐stent pressure measurements. Performing manometry after stent placement should be routinely performed in order to detect persistent venous pressure gradient.

Right ventricular pressure response to +GZ acceleration stress

1982 ◽  
Vol 53 (4) ◽  
pp. 908-913 ◽  
Author(s):  
J. E. Whinnery ◽  
M. H. Laughlin
Keyword(s):  
Right Ventricular ◽  
Diastolic Pressure ◽  
Vena Cava ◽  
Systolic Pressure ◽  
Ventricular Pressure ◽  
Miniature Swine ◽  
Right Ventricular Systolic Pressure ◽  
Ventricular Systolic Pressure ◽  
The Right ◽  
Acceleration Stress

Measurements of right ventricular pressure in miniature swine were made at +Gz levels from +1 through +9 Gz. Polyethylene catheters were chronically placed in the cranial vena cava of five 2-yr-old female miniature swine (35–50 kg). The catheters were large enough to allow the introduction of a Millar pressure transducer into the venous system for placement in the right heart. The animals were fitted with an abdominal anti-G suit, restrained in a fiberglass couch, and exposed to the various +Gz levels on a centrifuge while fully conscious and unanesthetized. Right ventricular pressure and heart rate were measured during and for 2 min following 30-s exposures to each level of +Gz stress. The maximum right ventricular systolic pressure observed during +Gz was 200 Torr at +5 Gz with the maximum diastolic pressure being 88 Torr observed at +5 Gz. Mean heart rates were 200–210 beats/min at all levels of +Gz greater than or equal to +3 Gz when the animal remained stable. Mean maximum right ventricular pressures during +Gz stress were observed to increase through +5 Gz (85 Torr) and to decrease at higher levels of +Gz, indicating that through +5 Gz there is at least a partial compensation during acceleration stress. Decompensation in response to the stress began to occur during acceleration above +5 Gz with all animals decompensating during +9 Gz.

Ventricular systolic interdependence: volume elastance model in isolated canine hearts

1987 ◽  
Vol 253 (6) ◽  
pp. H1381-H1390 ◽  
Author(s):  
W. L. Maughan ◽  
K. Sunagawa ◽  
K. Sagawa
Keyword(s):  
Left Ventricle ◽  
Right Ventricle ◽  
Cross Talk ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Ventricular Free Wall ◽  
Free Wall ◽  
Right Ventricular Free Wall ◽  
Systolic Volume ◽  
The Right

To analyze the interaction between the right and left ventricle, we developed a model that consists of three functional elastic compartments (left ventricular free wall, septal, and right ventricular free wall compartments). Using 10 isolated blood-perfused canine hearts, we determined the end-systolic volume elastance of each of these three compartments. The functional septum was by far stiffer for either direction [47.2 +/- 7.2 (SE) mmHg/ml when pushed from left ventricle and 44.6 +/- 6.8 when pushed from right ventricle] than ventricular free walls [6.8 +/- 0.9 mmHg/ml for left ventricle and 2.9 +/- 0.2 for right ventricle]. The model prediction that right-to-left ventricular interaction (GRL) would be about twice as large as left-to-right interaction (GLR) was tested by direct measurement of changes in isovolumic peak pressure in one ventricle while the systolic pressure of the contralateral ventricle was varied. GRL thus measured was about twice GLR (0.146 +/- 0.003 vs. 0.08 +/- 0.001). In a separate protocol the end-systolic pressure-volume relationship (ESPVR) of each ventricle was measured while the contralateral ventricle was alternatively empty and while systolic pressure was maintained at a fixed value. The cross-talk gain was derived by dividing the amount of upward shift of the ESPVR by the systolic pressure difference in the other ventricle. Again GRL measured about twice GLR (0.126 +/- 0.002 vs. 0.065 +/- 0.008). There was no statistical difference between the gains determined by each of the three methods (predicted from the compartment elastances, measured directly, or calculated from shifts in the ESPVR). We conclude that systolic cross-talk gain was twice as large from right to left as from left to right and that the three-compartment volume elastance model is a powerful concept in interpreting ventricular cross talk.

scholarly journals Dynamic anatomical study of cardiac shunting in crocodiles using high-resolution angioscopy

1996 ◽  
Vol 199 (2) ◽  
pp. 359-365 ◽  
Author(s):  
M Axelsson ◽  
C E Franklin ◽  
C O Löfman ◽  
S Nilsson ◽  
G C Grigg
Keyword(s):  
High Resolution ◽  
Connective Tissue ◽  
Right Ventricle ◽  
Anatomical Study ◽  
Systemic Circulation ◽  
Outflow Tract ◽  
Aortic Valves ◽  
Aortic Blood Pressure ◽  
The Right

Prolonged submergence imposes special demands on the cardiovascular system. Unlike the situation in diving birds and mammals, crocodilians have the ability to shunt blood away from the lungs, despite having an anatomically divided ventricle. This remarkable cardiovascular flexibility is due in part to three anatomical peculiarities: (1) an 'extra' aorta (the left aorta) that leaves the right ventricle and allows the blood from the right ventricle to take an alternative route into the systemic circulation instead of going to the lungs; (2) the foramen of Panizza, an aperture that connects the right and left aortas at their base immediately outside the ventricle; and (3) a set of connective tissue outpushings in the pulmonary outflow tract in the right ventricle. Using high-resolution angioscopy, we have studied these structures in the beating crocodile heart and correlated their movements with in vivo pressure and flow recordings. The connective tissue outpushings in the pulmonary outflow tract represent an active mechanism used to restrict blood flow into the lungs, thus creating one of the conditions required for a right-to-left shunt. We observed that the foramen of Panizza was obstructed by the medial cusp of the right aortic valve during most of systole, effectively differentiating the left and right aortic blood pressure. During diastole, however, the foramen remained open, allowing pressure equilibration between the two aortas. Contrary to current theories, we found that the left aortic valves were unable to cover the foramen of Panizza during any part of the cardiac cycle, supporting the reversed foramen flow hypothesis. This would ensure a supply of blood to the coronary and cephalic circulation during a complete shut-down of the left side of the heart, such as might occur during prolonged submergence.

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