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PubMed2006

Echocardiographic estimation of pulmonary pressures.

Cardiac ultrasound plays a pivotal role in assessing pulmonary artery pressures. Estimation of right atrial pressure can be derived from the dimensions and respiratory variation of the inferior vena cava and Doppler modalities provide an accurate and comprehensive evaluation of right ventricular and pulmonary artery pressures. Peak pulmonary artery pressure can be calculated from continuous wave Doppler sampling of the tricuspid regurgitant jet, while pulsed wave Doppler sampling of the pulmonary regurgitant jet allows evaluation of mean and diastolic pulmonary artery pressures. In patients with tricuspid regurgitation that is either absent or not adequately detectable by Doppler method, Doppler right ventricular outflow tract investigation can be helpful. Recent data indicate that analysis of right ventricular function using myocardial Doppler echocardiography may also provide new insights for the non-invasive estimation of pulmonary artery pressures. In particular, right ventricular isovolumic relaxation time measured by myocardial Doppler echocardiography at the tricuspid annulus may provide an alternative method for estimating pulmonary artery pressure, especially in patients with tricuspid regurgitation not detectable or spectral Doppler not properly interpretable.

Atrial Function, Right↗
PubMed1991

Alterations in transesophageal pulsed Doppler indexes of filling of the left ventricle after pericardiotomy.

The impact of pericardial constraint on patterns of left ventricular filling was measured by transesophageal pulsed Doppler echocardiography in 30 patients undergoing elective nonvalvular cardiac surgery. Peak early left ventricular filling velocity increased from 0.52 +/- 0.11 to 0.56 +/- 0.15 m/s (p less than 0.05) and early left ventricular filling fraction increased from 60 +/- 9% to 65 +/- 9% (p less than 0.005) after pericardiotomy. The study group was retrospectively subdivided into two groups based on the prepericardiotomy mean right atrial pressure, an index of intrapericardial pressure and hence pericardial constraint. In 13 patients with a mean right atrial pressure less than 6 mm Hg, no significant changes in early left ventricular filling were evident after pericardiotomy. In 17 patients with a mean right atrial pressure greater than or equal to 6 mm Hg indicative of a greater degree of pericardial constraint before pericardiotomy, significant increases in peak early filling velocity (0.52 +/- 0.13 to 0.57 +/- 0.19 m/s, p less than 0.05), peak early filling rate (4.29 +/- 0.67 to 4.66 +/- 0.86 stroke volumes/s, p less than 0.05) and early left ventricular filling fraction (57 +/- 7% to 63 +/- 8%, p less than 0.001) were measured after pericardiotomy. Thus, the pericardium does constrain early left ventricular filling and its effects are more pronounced in patients with an elevated right atrial pressure.

Aged↗
PubMed2001

Hemodynamic changes with right lateral decubitus body positioning in the tilted porcine heart.

BACKGROUND: In beating-heart coronary surgical procedures, exposure of posterior vessels through sternotomy causes cardiac function to deteriorate. We hypothesized that turning the subject to the right lateral decubitus position before cardiac retraction improves exposure of posterior vessels and preserves cardiac pump function on displacement. METHODS: Eight 80-kg open-chest pigs were instrumented with catheter-tip manometers. After a stepwise 60-degree turn to the right lateral decubitus position of the body, the heart was retracted anteriorly to 90 degrees with a suction stabilizer. RESULTS: Right lateral body positioning caused an approximately 45-degree right deviation of the apex, thereby exposing the left atrial groove. Stroke volume, mean arterial pressure, right atrial pressure, and right ventricular end-diastolic pressure increased to 106% +/- 5% (mean +/- standard error of the mean, p = 0.31), 106% +/- 3% (p = 0.01), 129% +/- 8% (p = 0.001), and 171% +/- 14% (p = 0.002), respectively, compared with control values. In contrast, left atrial pressure decreased to 73% +/- 6% (p = 0.007), whereas left ventricular preload remained unchanged (110% +/- 8%, p = 0.26). Additional anterior displacement to 90 degrees fully exposed the posterior vessels, and stroke volume decreased to 90% +/- 3% (p = 0.01) and mean arterial pressure to 93% +/- 5% (p = 0.07) at the expense of further increased right ventricular preload (256% +/- 28%, p < 0.001). CONCLUSIONS: By placing the subject in the right lateral decubitus position, exposure through sternotomy of posterior vessels in the beating porcine heart was facilitated while mean arterial pressure was maintained.

Animals↗
PubMed1998

Effects of cardiomyoplasty on right ventricular filling during volume loading.

BACKGROUND: Although cardiomyoplasty (CMP) is thought to improve ventricular systolic function, its effects on ventricular diastolic function are not clear. Especially the effects on right ventricular diastolic filling have not been fully investigated. Because pericardial influences are more pronounced in the right ventricle than in the left ventricle, CMP with its external constraint may substantially impair right ventricular diastolic filling. METHODS: Fourteen purebred adult beagles were used in this study. Seven underwent left posterior CMP, and 7 underwent a sham operation with a pericardiotomy and served as controls. Four weeks later, the hemodynamic effects of CMP were evaluated by heart catheterization before and after volume loading (central venous infusion of 10 mg/kg of 4.5% albumin solution for 5 minutes). RESULTS: In the CMP group, mean right atrial pressure and right ventricular end-diastolic pressure increased significantly from 3.1 +/- 1.2 mm Hg to 6.1 +/- 2.0 mm Hg (p < 0.001) and from 4.0 +/- 1.8 mm Hg to 9.6 +/- 2.5 mm Hg (p < 0.001), respectively. Volume loading in the control group did not significantly increase either variable. Right ventricular end-diastolic volume and stroke volume did not change significantly (from 53 +/- 9.3 mL to 60 +/- 9.0 mL and from 20 +/- 2.3 mL to 21 +/- 3.2 mL, respectively) in the CMP group. In the control group, however, right ventricular end-diastolic volume and stroke volume increased significantly from 45 +/- 7.7 mL to 63 +/- 14 mL (p < 0.05) and from 18 +/- 4.3 mL to 22 +/- 4.2 mL (p < 0.05), respectively. CONCLUSIONS: These results suggest that CMP may reduce right ventricular compliance and restrict right ventricular diastolic filling in response to rapid volume loading because of its external constraint.

Albumins↗
PubMed1992

[Determination of anaerobic threshold and influence of hemodynamics on exercise intolerance in patients after cardiac valve surgery].

In order to evaluate the exercise tolerance of the patients after cardiac valve surgery, the exercise stress test by supine bicycle ergometer was performed in 26 patients. An anaerobic threshold (AT) was determined by lactate threshold. The mixed venous oxygen saturation (SvO2) was measured simultaneously to assess the relationship between AT and SvO2 during exercise test. The study group consisted of 10 men (mean age: 46.2 years) and 16 women (mean age: 49.4 years). Each patient received either of following two programs: 1) a single step test of approximately 5 METS, which corresponded to the exercise tolerance level of NYHA functional Class II (Group A, 18 patients); and 2) a consecutive multi-staged test, which was begun at a worked of 25 W and increased by 25 W in every 3 minutes until the symptomatic maximum or ended at 100 W (Group B, 8 patients). Eleven patients (6 patients in Group A, 5 patients in Group B) had reached AT point during the test. SvO2 was 26.6 +/- 3.6% in group A patients, and 29.3 +/- 1.4% in group B patients at the point of AT. This data suggests that anaerobic metabolism begins at the level of SvO2 slightly less than 30%, and that SvO2 is a simple and usefull indicator for the estimation of AT. In patients with reduced exercise tolerance which was recognized by AT point at exercise stage of about 5 METS, the right atrial and pulmonary arterial mean pressure were higher than the others (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1999

Influence of right atrial pressure on the cardiac pacemaker response to vagal stimulation.

We have recently shown that the intrinsic rate response to an increase in right atrial pressure is augmented when cardiac muscarinic receptors are activated. This present study examines the cardiac pacemaker response to vagal stimulation at different values of right atrial pressure in isolated rat right atrium and in the rabbit heart in situ. In the rat atrium, when pressure was raised in steps from 2 to 10 mmHg, there was a progressive reduction in the response to vagal stimulation [40.5 +/- 7.2% reduction (mean +/- SE) at 8 mmHg, P < 0.01], which was independent of the level of vagal bradycardia, that persisted in the presence of the beta-adrenergic agonist isoproterenol. In barbiturate-anesthetized rabbits with cervical vagi cut and beta-adrenergic blockade, raising right atrial pressure approximately 2.5 mmHg by blood volume expansion reduced the bradycardia elicited by electrical stimulation of the peripheral end of the right vagus nerve (9.1 +/- 1.1% reduction, P < 0.0001). These results demonstrate that vagal bradycardia is modulated by the level of right atrial pressure and suggest that normally right atrial pressure may interact with cardiac vagal activity in the control of heart rate.

Animals↗
PubMed2000

Evidence of heterogeneous remodeling in canine atrial fibrillation.

Although electrophysiologic changes occur during atrial remodeling, little is known how remodeling affects atrial fibrillation (AF) organization. We hypothesized that, in animals with long-term rapid atrial rates and a rapid ventricular response, AF would be more disorganized than in animals with rapid atrial rates only. In 8 dogs, chronic AF was created by 6 weeks of continuous rapid atrial pacing. In this group, the ventricular response to AF was spontaneous and unaltered. Twenty-one epochs of AF were epicardially mapped from the right and left atria. In 6 dogs, chronic AF was also created with rapid atrial pacing, however, the AV node was ablated and the ventricles were VVI paced at 80 BPM. Only 1 epoch of AF per dog was mapped. Atrial cycle length (CL) and spatial organization were compared. In chronic AF with a spontaneous ventricular rate, left atrial CL (96+/-14 ms) averaged 24 ms shorter than right atrial CL (121+/-18 ms) (P < .0001). With VVI pacing, AF CL was longer than in the dogs with the spontaneous ventricular rate. However, the left atrial CL (109+/-30 ms) was still significantly shorter than the right atrial CL (145+/-43 ms) (P < .001). Spatial organization values showed that during chronic AF with a spontaneous ventricular rate, the left atrium is more disorganized (2593+/-497) than the right atrium (2052+/-732) (P < .0001). With VVI pacing, the left atrium (2202+/-597) is still more disorganized than the right (1620+/-936) (P < .05). However, with VVI pacing, both atria appear less disorganized than dogs with VVI pacing. Atrial remodeling caused by heart failure that is superimposed on the remodeling due to rapid atrial rates causes the atria to be more disorganized than remodeling due to rapid atrial rates alone. However, in either case the left atrium is faster and more disorganized than the right atrium. Atrial fibrosis caused by the heart failure may increase the disorganization of AF activation.

Animals↗
PubMed1996

[Thromboendarterectomy in chronic thromboembolic pulmonary hypertension. Hemodynamics and right-heart function over the long term].

OBJECTIVE: To find out whether pulmonary thromboendarterectomy (PTE) can achieve lasting reduction of pulmonary vascular resistance in patients with pulmonary arterial hypertension due to chronic thromboembolism. PATIENTS AND METHODS: 45 patients (25 women, 20 men; mean age 45 +/- 24 [19-67] years) were re-investigated a mean of 21 (13-32) months after successful PTE. Two patients had then been in New York Heart Association (NYHA) stage II, 26 in stage III, and 17 in stage IV. In addition to clinical examination and chest radiogram 36 patients had right heart catheterization, 28 pulmonary angiography and 44 echocardiography. RESULTS: Definite improvement of symptoms had occurred in all. 34 were now in NYHA stage I, nine in stage II, and two in stage III. The pulmonary vascular resistance was significantly lower than before and immediately after PTE (pre-PTE: 1052 +/- 472 dyn.s.cm-5; post-PTE: 293 +/- 175 dyn.s.cm-5; at follow-up: 187 +/- 92 dyn.s.cm-5; P < 0.001 for follow-up vs pre-PTE; P < 0.05 for follow-up vs post-PTE). Correspondingly, cardiac index had significantly increased (3.0 +/- 0.5 vs 2.0 +/- 0.7 l/min.m2; P < 0.001). Radiological and echocardiographic examinations showed a definite decrease in right ventricular dimensions and improvement in right ventricular function. CONCLUSION: In patients with pulmonary arterial hypertension due to chronic pulmonary thromboembolism PTE can achieve a reduction in pulmonary vascular resistance with lasting improvement in right heart function and clinical symptoms.

Adult↗
PubMed2006

Echocardiographic measurement of ventricular function.

PURPOSE OF REVIEW: We review new findings concerning ventricular function in patients in intensive care units with shock or unexplained respiratory distress syndrome analyzed using echocardiography. RECENT FINDINGS: Bedside echocardiography is not only an imaging technique but should be considered as a hemodynamic method. Left-ventricular systolic function can be assessed in daily clinical practice by measuring shortening fraction, fraction area change and ejection fraction. But these indices are dependent on load conditions. Index of myocardial performance can be also used. Rate of left-ventricular pressure increase may be measured from mitral regurgitation. Other indices such a maximal elastance and preload-adjusted maximal power were developed to evaluate myocardial systolic function but are not still used in clinical practice in patients in intensive care. Cardiac output measurement can be calculated easily from aortic annulus diameter and the velocity time integral of aortic blood flow. To complete the assessment of ventricular function, left-ventricular diastolic function and pressure as well as right ventricular size, septal movement and right pressures should be analyzed. SUMMARY: Using echocardiography the intensivist can examine both the mechanism and the cause of shock or pulmonary edema. It is time to increase the use of this technique in intensive care units.

Atrial Function, Right↗
PubMed2002

Independence of changes in right atrial pressure and central venous pressure.

Dynamics of changes in right-atrial pressure and venous pressure measured in the inferior and superior vena cava at their orifices (central venous pressure) after bolus injection of 20 ml physiological saline or epinephrine (5.0 mg/kg) was studied in acute experiments on cats. The initial pressure in the right atrium was equal to that in caval veins. Pressor stimuli either increased or decreased the right atrial pressure, but always increased blood pressure in the caval veins. Moreover, right atrial pressure returned to the initial level more rapidly compared to that in caval veins. Our results suggest that the dynamics of the right-atrial pressure does not reflect the shifts in the central venous pressure.

Animals↗
PubMed2003

Influence of changes in intrathoracic and central venous pressure on cardiac filling dynamics.

Changes in the ratio between intrathoracic and central venous pressure were studied in narcotized cats under conditions of constant positive or negative pressure ventilation. Transformation of elastic characteristics in the respiratory system caused by changes in intrathoracic pressure led to inversion of the ratio between transpulmonary intrathoracic and central venous pressure determining right atrial filling pressure.

Animals↗
PubMed2005

Right atrial pressure: determinant or result of change in venous return?

According to the concept of Guyton, cardiac output is largely controlled by venous return, which is determined by the difference between mean systemic venous pressure and right atrial pressure. In the analysis of the venous return curve, other authors have suggested that right atrial pressure is the dependent variable and venous return is the independent variable (right atrial pressure decreased because cardiac output increased). The present report analyzes this historical debate, which has already lasted > 50 years.

Atrial Function, Right↗
PubMedDate not supplied

Comparison of right atrial pressure and central venous pressures measured at various anatomical locations in children.

PURPOSE: To compare the right atrial pressure to the central venous pressures measured at different points in spontaneously breathing children and try to find a formula to estimate right atrial pressure by central venous pressure measurement. METHODS: Fifty-one children, aged 5 +/- 4.7 years, who underwent right heart catheterization were studied. All patients were sedated and breathed naturally. The mean pressure was the electronic mean of nine heart beats calculated by Philips BC4000 digital angiographic system. Mean pressure of the right atrium was compared to those measured at the high superior vena cava (SVC), low SVC, high inferior vena cava (IVC) (T10-11), middle IVC (L1-2), low IVC (L3-4), and iliac vein (L5-S1). RESULTS: Mean pressures of central veins were significantly higher than that of the right atrium (all p<0.01). Adjusted central venous pressures of SVC-0.5, high IVC-1.5, middle IVC-2, low IVC-2.5, and iliac vein-3 (mmHg) had a good agreement with the right atrial pressure. CONCLUSIONS: Central venous pressures are significantly higher than the right atrial pressure in spontaneously breathing children. Adjusted pressures of SVC-0.5, high IVC-1.5, middle IVC-2, low IVC-2.5, and iliac vein-3 (mmHg) can accurately reflect the right atrial pressure.

Atrial Function, Right↗
PubMed2002

Atrial components contributing to pseudo r' deflection in lead V1 in slow/fast atrioventricular nodal reentrant tachycardia: analysis of the atrial activation sequence by basket catheter isochronal mapping.

Electrocardiographic recognition of the P' wave during tachycardia is very useful in the diagnosis of supraventricular tachycardias. In slow/fast (S/F) atrioventricular nodal reentrant tachycardia (AVNRT), no discrete P' waves are observed on ECG and pseudo r' deflection in lead V1 (pseudo r') is commonly recognized. However, the atrial components that contribute to the genesis of pseudo r' in lead V1 have not been described and this study aimed to clarify them by analysis of the whole activation sequence of the right atrium using Basket catheter isochronal mapping. The study group comprised 48 patients with AVNRT. Pseudo r' was defined as an upward deflection in the terminal portion of the QRS complex during tachycardia that was not recognized during sinus rhythm and it occurred in 45 patients (94%). During S/F AVNRT, the retrograde atrial activation was earliest on His bundle electrogram, followed by the coronary sinus ostium, distal coronary sinus and high right atrium. Only the high lateral aspect of the right atrium was activated after the end of the QRS complex. The interval between the onset of QRS in multiple surface ECG leads and the atrial activities on high right atrium was similar to the V-r' interval in lead V1 (111+/-20ms, 117+/-11 ms) and correlated with the V-r' interval (r=0.56). Pseudo r' deflection in lead V1 is a highly sensitive indicator of S/F AVNRT, and appears to result from the activation of the superolateral aspect of the right atrium.

Adult↗
PubMed1996

Pulsatile venous Doppler flow in lower limbs: highly indicative of elevated right atrium pressure.

OBJECTIVE: The purpose of this study was to determine if pulsatile flow in lower limbs as seen on venous Doppler waveforms correlates with increased right atrium pressure. MATERIALS AND METHODS: Of 429 patients who, over a 14-month period, underwent venous Doppler imaging of the lower limb to exclude deep venous thrombosis, 343 records were available for review at the time of the study. Of these, 74 had right atrium pressure measurements available for correlation. Seventeen patients were excluded because of thrombosis in the common femoral vein. Six other patients were also excluded because the time difference between the Doppler and the correlative studies was more than 4 weeks. The remaining 51 patients constituted the study subjects. In 18 of these, the right atrium pressure was measured within 1 week, 31 within 2 weeks, 42 within 3 weeks, and 51 within 4 weeks. In the study, we evaluated the three major veins of the lower limb (the common femoral, superficial femoral, and popliteal) by venous Doppler imaging. Data from only the common femoral vein were included in our analysis because this vessel was the least involved with thrombosis. The findings were correlated with the presence or absence of right-sided heart failure as determined by right atrium pressure measurement. A Doppler waveform was considered pulsatile when it had a cyclic retrograde component. A right atrium pressure of more than 8 mm Hg was considered elevated. RESULTS: Of 51 patients, 17 (33%) had pulsatile lower limb venous Doppler flow waveforms and 33 (65%) had elevated right atrium pressure. We found a statistically significant correlation between the presence of these abnormal waveforms and elevated right atrium pressure. The sensitivity of lower limb venous Doppler imaging for detecting right-sided heart failure as determined by right atrium pressure measurement was 46%, specificity was 94%, positive predictive value was 94%, negative predictive value was 50%, and accuracy was 65%. CONCLUSION: Pulsatile lower limb venous Doppler waveform correlates well with right-sided heart failure, as indicated by a right atrium pressure measurement of more than 8 mm Hg. However, because of its low sensitivity, lower limb venous Doppler imaging cannot be used to screen for right-sided heart failure.

Adult↗
PubMed1993

[Effect of obstructive sleep apnea on preload of the right heart].

Obstructive sleep apnea (OSA) is characterized by a total inspiratory occlusion of the extrathoracic airways with persisting respiratory effort. During obstructive breathing efforts the intrathoracic pressure (ITP) falls below-20 Torr. This should augment venous return by depleting the blood from the extrathoracic veins into the thoracic veins, thus pre- and afterload of the right heart rises. Until now preload of the right heart during OSA was not measured. This study shows the filling pressures (tmPRA) of the right heart during OSA. In five patients the in- and expiratory right atrial pressure and the intrathoracic pressure were measured, beat by beat, during the non REM hour in which the most apnea episodes occurred. The tmPRA values were calculated as follows: tmPRA = PRA-ITP. The rising tmPRA with falling ITP shows that the venous return, during apnea episodes, rises mostly unhampered. Only in one patient did a cut-off of the increasing tmPRA occur. This patient showed a flow limitation of venous return. Two more patients developed different trends. One part of the measurements led to a linear increase of tmPRA, the other part shows a plateau up from a certain ITP. In two patients tmPRA increases linearly, in the extreme, with decreasing ITP. This indicates no flow limitation of venous return. The results of this investigation suggest that the protective mechanism of the limitation of venous return, occurring under artificial conditions, does not regularly appear in patients with OSA. This leads to repetitive volume overloads of the right heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗