Significant left ventricular contributions to right ventricular systolic function. Mechanism and clinical implications

Diuretic vs. placebo in intermediate-risk acute pulmonary embolism: a randomized clinical trial

AIMS

The role of diuretics in patients with intermediate-risk pulmonary embolism (PE) is controversial. In this multicentre, double-blind trial, we randomly assigned normotensive patients with intermediate-risk PE to receive either a single 80 mg bolus of furosemide or a placebo.

METHODS AND RESULTS

Eligible patients had at least a simplified PE Severity Index (sPESI) ≥1 with right ventricular dysfunction. The primary efficacy endpoint assessed 24 h after randomization included (i) absence of oligo-anuria and (ii) normalization of all sPESI items. Safety outcomes were worsening renal function and major adverse outcomes at 48 hours defined by death, cardiac arrest, mechanical ventilation, or need of catecholamine. A total of 276 patients underwent randomization; 135 were assigned to receive the diuretic, and 141 to receive the placebo. The primary outcome occurred in 68/132 patients (51.5%) in the diuretic and in 49/132 (37.1%) in the placebo group (relative risk = 1.30, 95% confidence interval 1.04-1.61; P = 0.021). Major adverse outcome at 48 h occurred in 1 (0.8%) patients in the diuretic group and 4 patients (2.9%) in the placebo group (P = 0.19). Increase in serum creatinine level was greater in diuretic than placebo group [+4 µM/L (-2; 14) vs. -1 µM/L (-11; 6), P < 0.001].

CONCLUSION

In normotensive patients with intermediate-risk PE, a single bolus of furosemide improved the primary efficacy outcome at 24 h and maintained stable renal function. In the furosemide group, urine output increased, without a demonstrable improvement in heart rate, systolic blood pressure, or arterial oxygenation.ClinicalTrials.gov identifier NCT02268903.

Acute effects of inhaled iloprost on intracardiac conduction in patients with pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a severe, life-threatening disorder despite the availability of specific drug therapy. A lack of endogenous prostacyclin secondary to downregulation of prostacyclin synthase in PAH may contribute to vascular pathologies. Therefore, prostacyclin and its analogs including inhaled iloprost may decrease pulmonary arterial pressure and ventricular pressure.

METHODS

Here, we studied that acute effects of iloprost used in pulmonary vasoreactivity testing on the intracardiac conduction system in patients with PAH. A total of 35 (15 idiopathic PAH, 20 congenital heart disease) patients with PAH were included in this prospective study. Patients were divided into two groups: 22 patients with negative pulmonary vasoreactivity in group 1 and 13 with positive pulmonary vasoreactivity in group 2. Electrophysiological parameters including basic cycle length, atrium-His (AH) interval, His-ventricle (HV) interval, PR interval, QT interval, QRS duration, Wenckebach period, and sinus node recovery time (SNRT) were evaluated before and after pulmonary vasoreactivity testing in both groups.

RESULTS

The AH interval (81 [74-93]; 80 [65.5-88], p = 0.019) and SNRT (907.7 ± 263.4; 854.0 ± 288.04, p = 0.027) was significantly decreased after pulmonary vasoreactivity testing. Mean right atrium pressure was found to be correlated with baseline AH (r = 0.371, p = 0.031) and SNRT (r = 0.353, p = 0.037).

CONCLUSION

Inhaled iloprost can improve cardiovascular performance in the presence of PAH, primarily through a reduction in right ventricular afterload and interventricular pressure. Decreased pressure on the interventricular septum and ventricles leads to conduction system normalization including of the AH interval and SNRT due to resolution of inflammation and edema.

Importance of Nonlongitudinal Motion Components in Right Ventricular Function: Three-Dimensional Echocardiographic Study in Healthy Volunteers

BACKGROUND

Global right ventricular (RV) function is determined by the interplay of different motion components related to the myofiber architecture, and the relative importance of these components is still not thoroughly characterized. The aims of this study were to quantify the relative contributions of longitudinal, radial, and anteroposterior motion components to global RV function and to examine their determining factors in a large cohort of healthy volunteers using three-dimensional echocardiography.

METHODS

Three hundred healthy adults with a balanced age range and an equal sex distribution were investigated at two centers. A three-dimensional mesh model of the right ventricle was generated, and its motion was decomposed along the three anatomically relevant axes. Multiplicative relative contributions were measured by dividing the ejection fraction (EF) values generated by shortening in the longitudinal, radial, and anteroposterior directions by global RV EF (longitudinal EF index [LEFi], radial EF index [REFi], and anteroposterior EF index, respectively). The circumferential contribution was defined as shortening in the radial and anteroposterior directions, omitting only longitudinal shortening.

RESULTS

Circumferential EF index was markedly higher compared with LEFi (79 ± 7% vs 47 ± 9%, P < .001). LEFi (47 ± 9%) and anteroposterior EF index (49 ± 7%) were found to be similar in the pooled population, whereas REFi (44 ± 10%) was lower (P < .001). In younger individuals (20-39 years of age), the relative contribution of longitudinal shortening was significantly higher compared with the radial component; however, in the older age groups, LEFi and REFi were comparable. Age, body surface area, heart rate, and RV end-diastolic volume were independent predictors of LEFi and REFi, but all with opposite effects on the two motion directions.

CONCLUSIONS

In contrast to the traditional viewpoint, the contributions of the radial and anteroposterior motion directions may be of comparable significance with that of longitudinal shortening in determining global RV function. Standard parameters referring only to longitudinal shortening of the right ventricle may be inadequate to characterize RV function thoroughly.

The Right Ventricle-You May Forget it, but It Will Not Forget You

Right ventricular (RV) dysfunction and failure are common and often overlooked causes of perioperative deterioration and adverse outcomes. Due to its unique pathophysiologic underpinnings, RV failure often does not respond to typical therapeutic measures such as volume resuscitation and often worsens when therapy is escalated and mechanical ventilation is begun, with a danger of irreversible cardiovascular collapse and death. The single most important factor in improving outcomes in the context of RV failure is anticipating and recognizing it. Once established, a vicious circle of systemic hypotension, and RV ischemia and dilation is set in motion, rapidly spiraling down into a state of shock culminating in multi-organ failure and ultimately death. Therapy of RV failure must focus on rapidly reestablishing RV coronary perfusion, lowering pulmonary vascular resistance and optimizing volemia. In parallel, underlying reversible causes should be sought and if possible treated. In all stages of diagnostics and therapy, echocardiography plays a central role. In severe cases of RV dysfunction there remains a role for the use of the pulmonary artery catheter. When these mostly simple measures are undertaken in a timely fashion, the spiral of death of RV failure can often be broken or even prevented altogether.

Afterload dependence of right ventricular myocardial deformation: A comparison between tetralogy of Fallot and atrially corrected transposition of the great arteries in adult patients

Background

Prior studies suggested that myocardial deformation is superior to conventional measures for assessing ventricular function. This study aimed to evaluate right ventricular (RV) myocardial deformation in response to increased afterload. Patients with the RV in the systemic position were compared with patients with the RV in the sub-pulmonic position with normal or only slightly elevated systolic right ventricular pressure. Correlations between global longitudinal strain (GLS), radial strain, atrioventricular plane displacement (AVPD), and exercise capacity were evaluated.

Methods

44 patients with congenital heart defect were enrolled in the study. The control group consisted of seven healthy volunteers. All patients underwent cardiovascular magnetic resonance (CMR) and cardiopulmonary exercise testing. We assessed biventricular myocardial function using CMR based feature tracking and compared the results to anatomic volumes.

Results

Strain analysis and displacement measurements were feasible in all participants. RVGLS and RVAVPD were reduced in both study groups compared to the control group (p<0.001). Left ventricular (LV) radial strain was significantly lower in patients with a systemic RV than in those with a subpulmonic RV and lower than in controls (p<0.001). Both LVAVPD and RVAVPD were significantly depressed in patients compared to controls (p<0.05). RVAVPD was more depressed in patients with a high systolic RV pressure than in those with normal RV pressure (p<0.001). RVAVPD did not correlate with exercise capacity in either study group. Exercise capacity in both patient groups was depressed to levels reported in previous studies, and did not correlate with RVGLS.

Conclusions

Both study groups had abnormal myocardial deformation and increased RV volumes. RVGLS in patients was lower than in controls, confirming the effect of increased afterload on myocardial performance.

Echocardiographic approach to cardiac tamponade in critically ill patients

Cardiac tamponade should be considered in a critically ill patient in whom the cause of haemodynamic shock is unclear. When considering tamponade, transthoracic echocardiography plays an essential role and is the initial investigation of choice. Diagnostic sensitivity of transthoracic echocardiography is dependent on image quality, and in some cases a transoesophageal approach may be required to confirm the diagnosis. Knowledge of the pathophysiology and echocardiographic features of cardiac tamponade are essential for the practicing Intensivist. This review presents an approach to the recognition, diagnosis, and treatment of cardiac tamponade in critically ill patients.

Cardiopulmonary Interactions

OBJECTIVES

The objectives of this review are to discuss the mechanisms by which respiration impacts cardiovascular function and vice versa, with an emphasis on the impact of these interactions in pediatric cardiac critical care.

DATA SOURCE

A search of MEDLINE was conducted using PubMed.

CONCLUSIONS

In the presence of underlying cardiac and respiratory disease, the interplay between these two systems is significant and plays a pivotal role in the pathophysiology of acute and chronic phases of a wide spectrum of diseases. An understanding of these relationships is essential to optimizing the care of critically ill patients.

Right ventricular dysfunction in a hypertensive population stratified by patterns of left ventricular geometry

Introduction

The aim of this study was to assess the prevalence, determinants and correlates of right ventricular (RV) systolic and diastolic dysfunction (RVSD and RVDD, respectively) in hypertensives, stratified by left ventricular (LV) geometric patterns.

Methods

The study was carried out in Aminu Kano Teaching Hospital in Kano, Nigeria, and was cross-sectional in design. Hypertensive subjects referred for echocardiography were consecutively recruited after satisfying the inclusion criteria. RVSD was defined as either tricuspid annular plane systolic excursion (TAPSE) of < 16 mm, or peak velocity of the systolic wave (S_m) in tissue Doppler imaging (TDI) of the RV lateral tricuspid annulus of < 10 cm/s, or both. RVDD was defined as the ratio of < 1.0 of the peak velocities of the early (E_m) to late (A_m) diastolic waves in the TDI of the RV lateral tricuspid annulus. Subjects with normal LV geometry (NG) served as controls, and were compared with those who had eccentric (EH) or concentric (CH) LV hypertrophy or concentric LV remodelling.

Results

A total of 128 subjects were recruited. Overall, the prevalence of RVDD almost doubled that of RVSD in the studied subjects (61.72 vs 32.03%, respectively). Subjects with EH had the highest prevalence of RVSD (52.63%), while those with CH had the lowest prevalence (20.69%) (p < 0.01). By contrast, the prevalence of RVDD was high across the four groups without significant statistical difference; as high as 68.52% in subjects with NG and as low as 42.86% in those with CR. LVEF was the only independent determinant of RVSD after controlling for confounding variables, while age was the only determinant of RVDD. Likewise, age was the only correlate for E_m:A_m ratio, while the best correlate for both TAPSE and S_m was LVEF.

Conclusion

The study has revealed that about two-thirds of the hypertensives had RVDD while about one-third had RVSD. Subjects with EH had the highest prevalence of RVSD, while RVDD was common across all the groups. LVEF and age were the only independent determinants of RVSD and RVDD, respectively.

Feasibility of right ventricular longitudinal systolic function evaluation with transthoracic echocardiographic indices derived from tricuspid annular motion: a preliminary study in acute respiratory distress syndrome

INTRODUCTION

Assessment of right ventricular (RV) function in patients with acute respiratory distress syndrome (ARDS) remains challenging. Transthoracic echocardiographic (TTE) indices based on longitudinal systolic RV function are now considered as a reliable evaluation of RV function. We investigated feasibility of two methods in ARDS patients.

METHODS

Prospective observational study. TTE was performed after 12-36 hours of mechanical ventilation. Feasibility of tricuspid annular motion (S(t) ), tricuspid annular plane systolic excursion (TAPSE) was compared to usual two-dimensional (2D) study: fractional area change (RV(FAC) ) and ratio of right to left ventricular end-diastolic area (RVEDA/LVEDA).

RESULTS

Fifty patients were investigated, with TTE possible in all but two patients. Feasibility was 62% for RV(FAC), 72% for RVEDA/LVEDA, and 96% for TAPSE and S(t). RV dilatation (RVEDA/LVEDA ≥ 0.60) was found in 16 patients, including 4 patients with acute cor pulmonale. A longitudinal RV dysfunction (TAPSE < 12 mm or S(t) < 11.5 cm/sec) was suspected in 30% of patients. Relation between both longitudinal indices was modest (r(2) = 0.36, P < 0.001). TAPSE (but not S(t) ) was found poorly related to RV(FAC) (r(2) = 0.27, P = 0.03). Both indices were related to LV function (S(t) : r(2) = 0.27, TAPSE: r(2) = 0.17, both P < 0.05).

CONCLUSION

Despite a superior feasibility than 2D study, our results suggest that both indices may not bring identical information to echo study. TAPSE may be more adapted to ICU use than S(t) . Both should be further investigated in terms of analysis of RV function and ventricular interdependence. Their relations with LV function may limit their use as sole markers of RV function in this population.

Assessment of right ventricular systolic function using tricuspid annular-plane systolic excursion in Nigerians with systemic hypertension

AIM

Right ventricular (RV) systolic function in patients with hypertensive heart disease (HHD) is not well characterised. The primary aim of this study was to assess the systolic function of the right ventricle in patients with HHD using tricuspid annular-plane systolic excursion (TAPSE).

METHODS

The study was cross-sectional in design and carried out in Kano, Nigeria. Patients were recruited if they had HHD on echocardiography and were at least 15 years of age. Patients with other cardiac pathologies such as ischaemic and valvular heart diseases were excluded. Patients were considered to have abnormal RV systolic function if they had reduced values of TAPSE ( < 15 mm). A p-value of < 0.05 was considered statistically significant.

RESULTS

A total of 186 patients were serially recruited over seven months. Of these, 131 (70.4%) had normal RV systolic function (group 1) and 55 patients (29.6%) had abnormal function (group 2). Group 2 patients were older (p = 0.002) and had a higher prevalence of peripheral oedema (p = 0.002), moderate to severe dyspnoea, higher heart rate and lower left ventricular ejection fraction (p < 0.001). Atrial arrhythmias were also more prevalent among group 2 patients (p < 0.05). The best correlate to TAPSE was the septal mitral annularplane systolic excursion (r = +0.541, p < 0.001). Several variables such as age predicted the presence of reduced TAPSE.

CONCLUSION

The study found that almost one-third of patients with HHD in Kano had RV systolic dysfunction as defined by reduced TAPSE, and these patients had a greater prevalence of factors associated with morbidity and mortality.

Case report: paradoxical ventricular septal motion in the setting of primary right ventricular myocardial failure

PURPOSE

In this report, a case of right ventricular (RV) failure, hemodynamic instability, and systemic organ failure is described to highlight how paradoxical ventricular systolic septal motion (PVSM), or a rightward systolic displacement of the interventricular septum, may contribute to RV ejection.

CLINICAL FEATURES

Multiple inotropic medications and vasopressors were administered to treat right heart failure and systemic hypotension in a patient following combined aortic and mitral valve replacement. In the early postoperative period, echocardiographic evaluation revealed adequate left ventricular systolic function, akinesis of the RV myocardial tissues, and PVSM. In the presence of PVSM, RV fractional area of contraction was > or =35% despite akinesis of the primary RV myocardial walls. The PVSM appeared to contribute toward RV ejection. As a result, the need for multiple inotropes was re-evaluated, in considering that end-organ dysfunction was the result of systemic hypotension and prolonged vasopressor administration. After discontinuation of phosphodiesterase inhibitors, native vascular tone returned and the need for vasopressors declined. This was followed by recovery of systemic organ function. Echocardiographic re-evaluation two years later, revealed persistent akinesis of the RV myocardial tissues and PVSM, the latter appearing to contribute toward RV ejection.

CONCLUSIONS

This case highlights the importance of left to RV interactions, and how PVSM may mediate these hemodynamic interactions.

Cardiopulmonary interaction

OBJECTIVE

To highlight and review the physiology and pathophysiology of cardiopulmonary interaction in the critically ill pediatric patient.

DATA SOURCE

A MEDLINE-based literature source. OUTLINE OF REVIEW: This review is divided into two sections: 1) The physiologic basis of cardiopulmonary interaction, and 2) critical clinical conditions in which cardiac and/or pulmonary dysfunction impact each other in the provision of adequate oxygen delivery. The physiology section focuses on the original research identifying fundamental volume-pressure and pressure-flow relationships and then proceeds to discuss how changes in intrathoracic pressure and lung volume affect ventricular loading conditions. The clinical section chooses several common scenarios in which this normal physiology is altered and an understanding of the impact of these physiologic aberrations on cardiac and/or pulmonary function is required to make sound management decisions.

CONCLUSIONS

Improving oxygen transport balance is the primary goal in the management of children with life-threatening disorders. To optimize the opportunity for a successful outcome, the intensivist must understand the complex relationship between the cardiac and pulmonary systems in the effort to provide sufficient oxygen to meet the body's metabolic demands. Furthermore, the application of therapies separately designed to support the function of the heart and the function of the lungs may be synergistic or antagonistic, further complicating the management scheme. We conclude that this review will encourage the reader to pursue further literature or perhaps engage in further research related to this often underappreciated but vital interplay between cardiac and pulmonary functions.

Effects of inhaled iloprost on right ventricular contractility, right ventriculo-vascular coupling and ventricular interdependence: a randomized placebo-controlled trial in an experimental model of acute pulmonary hypertension

Introduction

Prostacyclin inhalation is increasingly used to treat acute pulmonary hypertension and right ventricular failure, although its pharmacodynamic properties remain controversial. Prostacyclins not only affect vasomotor tone but may also have cAMP-mediated positive inotropic effects and modulate autonomic nervous system tone. We studied the role of these different mechanisms in the overall haemodynamic effects produced by iloprost inhalation in an experimental model of acute pulmonary hypertension.

Methods

In this prospective, randomized, placebo-controlled animal study, twenty-six pigs (mean weight 35 ± 2 kg) were instrumented with biventricular conductance catheters, a pulmonary artery flow probe and a high-fidelity pulmonary artery pressure catheter. The effects of inhaled iloprost (50 μg) were studied in the following groups: animals with acute hypoxia-induced pulmonary hypertension, and healthy animals with and without blockade of the autonomic nervous system.

Results

During pulmonary hypertension, inhalation of iloprost resulted in a 51% increase in cardiac output compared with placebo (5.6 ± 0.7 versus 3.7 ± 0.8 l/minute; P = 0.0013), a selective reduction in right ventricular afterload (effective pulmonary arterial elastance: 0.6 ± 0.3 versus 1.2 ± 0.5 mmHg/ml; P = 0.0005) and a significant increase in left ventricular end-diastolic volume (91 ± 12 versus 70 ± 20 ml; P = 0.006). Interestingly, right ventricular contractility was reduced after iloprost-treatment (slope of preload recruitable stroke work: 2.2 ± 0.5 versus 3.4 ± 0.8 mWatt·s/ml; P = 0.0002), whereas ventriculo-vascular coupling remained essentially preserved (ratio of right ventricular end-systolic elastance to effective pulmonary arterial elastance: 0.97 ± 0.33 versus 1.03 ± 0.15). In healthy animals, inhaled iloprost had only minimal haemodynamic effects and produced no direct effects on myocardial contractility, even after pharmacological blockade of the autonomic nervous system.

Conclusions

In animals with acute pulmonary hypertension, inhaled iloprost improved global haemodynamics primarily via selective pulmonary vasodilatation and restoration of left ventricular preload. The reduction in right ventricular afterload is associated with a paradoxical decrease in right ventricular contractility. Our data suggest that this reflects an indirect mechanism by which ventriculo-vascular coupling is maintained at the lowest possible energetic cost. We found no evidence for a direct negative inotropic effect of iloprost.

Right ventricular dimensions and function in isolated left bundle branch block: is there evidence of biventricular involvement?

BACKGROUND

Isolated left bundle branch block (LBBB) may be an expression of idiopathic cardiomyopathy affecting both ventricles. The present study was conducted to evaluate right ventricular (RV) dimensions and function in asymptomatic LBBB patients with mildly depressed left ventricular (LV) function.

METHODS

Fifteen patients with asymptomatic LBBB in whom coronary artery disease, hypertension, and valvular pathology was excluded were studied. Fifteen healthy volunteers and 15 idiopathic dilated cardiomyopathy LBBB patients served as controls. RV long axis and tricuspid annulus diameter were obtained, as were tricuspid annular plane systolic excursion (TAPSE) and peak systolic velocity (Sm) of the RV free wall annulus. Tricuspid regurgitation (TR) jets (peak TR jets) were used for RV pressure assessment.

RESULTS

RV dimensions were comparable between the asymptomatic LBBB patients and controls. RV functions of healthy volunteers and asymptomatic LBBB patients were similar (TAPSE: 24 +/- 3 and 24 +/- 4 mm, Sm: 13 +/- 2 and 13 +/- 3 cm/s, respectively), whereas functional parameters in idiopathic dilated cardiomyopathy patients were significantly reduced (TAPSE: 19 +/- 5 mm, Sm: 9 +/- 2 cm/s, both P < 0.01 by analysis of variance [ANOVA]). For the three groups combined, a significant inverse correlation between RV pressure (peak TR jets) and RV function (Sm) was observed (r =-0.52, P = 0.017).

CONCLUSIONS

In patients with an asymptomatic LBBB, RV dimensions and function are within normal range. The present study suggests that screening of RV functional parameters in asymptomatic LBBB patients is not useful for identification of an early-stage cardiomyopathy, and RV dysfunction is merely a consequence of increased RV loading conditions caused by left-sided heart failure and does not indicate a generalized cardiomyopathy affecting both ventricles.

What role does the right side of the heart play in circulation?

Right ventricular failure (RVF) is an underestimated problem in intensive care. This review explores the physiology and pathophysiology of right ventricular function and the pulmonary circulation. When RVF is secondary to an acute increase in afterload, the picture is one of acute cor pulmonale, as occurs in the context of acute respiratory distress syndrome, pulmonary embolism and sepsis. RVF can also be caused by right myocardial dysfunction. Pulmonary arterial catheterization and echocardiography are discussed in terms of their roles in diagnosis and treatment. Treatments include options to reduce right ventricular afterload, specific pulmonary vasodilators and inotropes.

Elevated brain natriuretic peptide and reduced exercise capacity in adult patients operated on for tetralogy of fallot is due to biventricular dysfunction as determined by the myocardial performance index

Although tetralogy of Fallot (TOF) can be repaired surgically, residual lesions that cause abnormal ventricular load can eventually lead to heart failure. Subclinical biventricular dysfunction in these patients may be detected only by using suitably sensitive indexes. The Tei index determined by the pulsed Doppler method enables the measurement of left ventricular (LV) and right ventricular (RV) function. This study was designed to evaluate the biventricular Tei indexes in adults with operated congenital heart disease and to correlate these indexes with cardiopulmonary capacity and neurohormonal activation. Fifty-nine patients with surgically corrected TOF and 52 patients with operated left-to-right-shunt defects were included in the study. Patients with TOF showed significantly greater LV and RV Tei indexes than those with left-to-right-shunt defects (LV Tei index 0.50 +/- 0.09 vs 0.34 +/- 0.05, RV Tei index 0.37 +/- 0.1 vs 0.25 +/- 0.06; p <0.0001). Peak oxygen uptake was significantly reduced in the patients with TOF (25 +/- 6 vs 32 +/- 6 ml x kg(-1) x min(-1), p <0.0001) and was correlated inversely with the LV Tei index (r = -0.61, p <0.0001). N-terminal-pro-brain natriuretic peptide was significantly increased in patients with TOF (150 +/- 141 vs 57 +/- 39 pg/ml, p <0.0001). In conclusion, in asymptomatic or minimally symptomatic patients with TOF, biventricular dysfunction is detected by the Tei index. Further indexes for heart failure in these patients are increased circulating plasma N-terminal-pro-brain natriuretic peptide and impaired peak oxygen uptake. The combined determinations of these 3 variables enable the identification of congenital heart disease with impaired cardiac function before they become clinically symptomatic.

Monitoring of right-sided heart function

PURPOSE OF REVIEW

Because the right side of the heart supplies blood to the pulmonary circulation, its integrity is required for both adequate respiratory and circulatory function. By reducing pulmonary perfusion, right-sided heart failure may compromise arterial oxygenation and left ventricular filling, and monitoring of right-sided heart function at the bedside in critically ill patients is fundamental. Two recent clinical commentaries have focused on the invaluable help provided by echocardiography for this purpose.

RECENT FINDINGS

Bedside echocardiography has supplanted invasive procedures as the best tool to evaluate right-sided heart function. Although not recent, this technique, previously reserved for cardiologists, has recently gained a larger acceptance in respiratory intensive care units. Echocardiographic examination detects excessive right ventricular afterload, visualized by septal dyskinesia, and its usual consequence, right ventricular enlargement, which impairs left ventricular filling.

SUMMARY

Monitoring of right-sided heart function is essential in a clinical setting associated with hemodynamic instability, such as severe sepsis or acute coronary artery obstruction, and also in that it is associated with increased pulmonary vascular resistance, as in massive pulmonary embolism or acute respiratory failure. Moreover, use of mechanical ventilation requires regular evaluation of its effects on the right side of the heart.

Intraaortic Balloon Pumping Improves Hemodynamics and Right Ventricular Efficiency in Acute Ischemic Right Ventricular Failure

BACKGROUND

Left ventricular unloading has a potentially deleterious effect in right ventricular failure as a result of altered septal interplay. However, a positive effect of an intraaortic balloon pump during right ventricular failure has been suggested. We investigated the impact of intraaortic balloon pumping on hemodynamics and both left and right ventricular function in an experimental model of isolated right ventricular failure.

METHODS

Sixteen anesthetized pigs (25 to 34 kg) were used in an in vivo model. Pressure-conductance catheters assessed right and left ventricular pressure-volume relationships. Acute right ventricular failure was induced by right coronary microembolization, and led to severely impaired right ventricular function, reduced cardiac output and arterial pressure, and an increased pulmonary vascular resistance and pulmonary arterial elastance. Animals were then randomized to balloon pump or control groups and evaluated with respect to hemodynamics and ventricular function after 1 hour.

RESULTS

Intraaortic balloon pumping did not alter right or left ventricular contractility. However, balloon pump-treated animals had significantly improved cardiac output (+18% +/- 18% versus -6% +/- 7%; p = 0.003) and mean arterial pressure (+36% +/- 30% versus -7% +/- 14%; p = 0.004) compared with controls. Animals in the balloon pump group had lower pulmonary vascular resistance (795 +/- 63 versus 912 +/- 259 dynes . sec . cm(-5); p < 0.01) and pulmonary arterial elastance (1.14 +/- 0.20 versus 1.69 +/- 0.65 mm Hg/mL; p < 0.01), and increased stroke volume (22.3 +/- 4.7 versus 17.9 +/- 4.7 mL; p = 0.016). Right ventricular efficiency was also improved in the balloon pump group (stroke work per pressure-volume area = 0.60 +/- 0.14 versus 0.41 +/- 0.12; p < 0.01).

CONCLUSIONS

Intraaortic balloon pump support does not alter right or left ventricular function in acute right ventricular failure. However, arterial pressure, cardiac output, and right ventricular efficiency are improved, possibly because of a balloon pump-induced reduction in pulmonary arterial resistance.

Evidence of adverse ventricular interdependence in patients with atrial septal defects

Right ventricular (RV) volume overload is associated with left ventricular (LV) distortion and dysfunction. The availability of transcatheter device closure of secundum atrial septal defect (ASD) provides an ideal model for investigating the immediate effects of elimination of RV volume overload and avoiding the confounding effects of surgery on LV function. Echocardiograms before and after device closure of ASD were analyzed for ejection fraction, percent changes in cross-sectional area and circumference, percent changes in free wall and septal endocardial lengths, and eccentricity. We enrolled 34 patients (median age 9 years) who underwent device closure of ASD (pulmonary to systemic shunt 1.6 +/- 0.4). Ejection fraction and LV end-diastolic volume, reflective of chamber preload, were significantly decreased in the presence of RV volume overload and normalized after defect closure with normalization of LV shape. Altered LV geometry secondary to RV volume overload was associated with regional variation in preload,such that diastolic circumference, a surrogate of myofiber preload, increased after closure of ASD secondary to a small increase in LV free wall arc length in conjunction with a much more significant increase in septal length. Thus, LV dysfunction associated with RV volume overload is secondary to altered chamber geometry and decreased myofiber preload. This physiology is immediately reversible and is independent of heart rate and afterload.

Screening for left ventricular dysfunction using a hand-carried cardiac ultrasound device

BACKGROUND

The hand-carried cardiac ultrasound (HCU) device is a recently introduced imaging device, which may be potentially useful in the primary care setting.

AIM

To test the screening potential of a HCU for the detection of left ventricular (LV) dysfunction by evaluating LV ejection fraction (LVEF) and inferior vena cava (IVC) collapse. Standard echocardiographic system (SE) and plasma brain natriuretic peptide (BNP) measurements were used as a reference.

METHODS

Eighty-eight consecutive patients (56 male, aged 59+/-12 years) with suspected LV dysfunction were enrolled in the study. The HCU-LVEF was visually estimated and the SE-LVEF was derived by the Simpson's biplane method. A LVEF <40% represented LV dysfunction. An IVC collapse of <50% and BNP levels > or =15 pmol/l were considered abnormal. The correlation of HCU-LVEF, HCU-IVC and BNP to the SE-LVEF and SE-IVC was analysed independently using 2x2 tables.

RESULTS

Six patients were excluded because of poor echo images. 19/82 patients had LV dysfunction. The HCU and BNP could identify 17 and 18 out of these 19 patients, respectively. The agreement for LVEF and IVC collapse between SE and HCU was 96% for both parameters. The sensitivity of IVC collapse, HCU-LVEF and BNP in identifying patients with LV dysfunction was 26, 89 and 94%, respectively.

CONCLUSION

A HCU device can reliably be used as a screening tool for LV dysfunction.

Echocardiography-derived variables predict outcome in patients with nonischemic dilated cardiomyopathy with or without a restrictive filling pattern

BACKGROUND

Despite recent therapeutic advances, patients with heart failure caused by dilated cardiomyopathy (DCM) still have high morbidity and mortality rates. In this study, we sought to assess the prognostic value of echocardiographic variables in patients with DCM and to assess the impact of a restrictive left ventricle filling pattern.

DESIGN

We conducted a retrospective cohort study of 337 patients with DCM, using the Royal Brompton Hospital Echocardiography database for the years 1994 to 1998.

METHODS AND RESULTS

There were 337 patients with a mean age of 53 +/- 15 years. One hundred ninety-five patients (58%) had a restrictive left ventricle filling pattern (RFP). There was a total of 74 deaths (22%) during the follow-up period (43 +/- 25 months). RFP more than tripled the risk of death (adjusted hazard ratio 3.2, 95% CI 1.8-5.7, P =.003). RFP is correlated with isovolumic relaxation time, incoordinate wall-motion, amplitude of right ventricular long axis excursion on M-mode echocardiography, and mitral regurgitation.

CONCLUSION

RFP is a powerful independent predictor of mortality in patients with nonischemic DCM. The risk associated with RFP is greatest among patients who had short isovolumic relaxation time, mitral regurgitation, incoordinate wall-motion, and depressed amplitude of right ventricular long axis excursion. Thus, echocardiography-derived variables may stratify patients with heart failure with DCM who are at high risk, for whom aggressive medical treatment or heart transplantation should be considered early.

Estimation of left ventricular function in right ventricular volume and pressure overload. Detection of early left ventricular dysfunction by Tei index

Although the effects of right ventricular (RV) volume and pressure overload (RVVO and RVPO) on ventricular septal motion are different, the differential effect on left ventricular (LV) function is still controversial. The Doppler-derived index (Tei index) combining systolic and diastolic ventricular function, defined as the sum of isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) divided by ejection time (ET), has been demonstrated to be a useful index to estimate LV function and to predict the prognosis of patients with congestive heart failure. This study was designed to evaluate the differential effects of RVVO and RVPO on LV function using the Tei index. Study patients consisted of 26 age-matched normal subjects, 22 patients with atrial septal defect (ASD) with normal or borderline RV pressure and 25 with primary pulmonary hypertension (PPH). All subjects had normal LV ejection fractions measured with 2-dimensional echocardiogram using biplane Simpson's method (61 +/- 4 vs 61 +/- 4 vs 63 +/- 8%, normal vs ASD vs PPH). Tei index was easily obtained in all subjects from transthoracic Doppler echocardiogram of LV inflow and outflow. Patients with ASD had normal ICT, IRT and ET, resulting in normal Tei index, however, patients with PPH had significantly prolonged ICT and IRT with shortened ET, resulting in a significant increase in Tei index (0.38 +/- 0.04 vs 0.36 +/- 0.03 vs 0.61 +/- 0.22, p < 0.001). Although RVVO due to ASD has no significant effects on LV function, RVPO due to PPH can adversely affect LV function. The Tei index is a simple and sensitive measure to assess LV function caused by RVVO or RVPO.

[Right ventricular function: physiological and physiopathological features]

Sinus and conus constitute the two cavities of the right ventricle. They are anatomically and functionally different. The sinus is a flow-generator and the conus a pressure-regulator. The coronary circulation of the right ventricle is provided by the right coronary artery and the left anterior descending artery. The right ventricle is perfused during systole and diastole. When oxygen demand increases, coronary arteries dilate and oxygen extraction rises. As for the left ventricle, right ventricular performance depends upon heart rate, rhythm, contractility and loading conditions. Ventricular interactions are very important for right ventricular function. Loading conditions and contractility of the left ventricle are of major significance for right ventricular performance. For the right ventricle, the end of the ejection is different from the end of the active contraction. The time between them allows to achieve ventricular emptying. This duration is linked to afterload. Presently, it is impossible to accurately and simply assess these conditions. Pressure and volume overloadings result in right ventricular failure. They are responsible for ventricular dilation and ischaemia with a decrease in cardiac output, generating a vicious circle. Treatment includes the removal of the cause, and the maintenance of systemic arterial pressure and biventricular contractility. It is difficult to assess the effects of intravenous vasodilators on right ventricular afterload.

Right ventricular overload causes the decrease in cardiac output after nitric oxide synthesis inhibition in endotoxemia

OBJECTIVE

To determine whether the decrease in cardiac output after nitric oxide synthase inhibition in endotoxemia is due to increased left ventricular afterload or right ventricular afterload.

DESIGN

Prospective, randomized, unblinded study.

SETTING

Research laboratory at an academic, university medical center.

SUBJECTS

Nonanesthetized, sedated, mechanically ventilated pigs.

INTERVENTIONS

Pigs were infused with 250 microg/kg of endotoxin over 30 mins. Normal saline was infused to maintain pulmonary artery occlusion pressure (PAOP) at a value not exceeding 1.5 times the baseline value. Left ventricular dimensions and function were studied using echocardiography. Right ventricular volumes and ejection fraction were determined via a rapid thermistor pulmonary artery catheter. We also measured mean arterial pressure (MAP), cardiac output, pulmonary arterial pressure, and calculated pulmonary and systemic resistances. Gastric tonometry was used as an index of gastric mucosal oxygenation and peripheral oxygenation. When MAP had decreased to < or =60 mm Hg or had decreased 30 mm Hg from baseline, nine animals received NG-nitro-L-arginine methyl ester (L-NAME) at 15 mg/kg to restore MAP to baseline. A second group of animals (n = 6) continued to receive normal saline, ensuring that PAOP did not exceed 1.5 times its baseline value. A third group of pigs (n = 5) did not receive endotoxin and served as the time control. In this group, a balloon was used to occlude the descending thoracic aorta and to increase MAP by approximately the same amount as in the L-NAME group.

MEASUREMENTS AND MAIN RESULTS

Endotoxin caused an increase in pulmonary arterial pressure and right ventricular volumes, and a decrease in gastric mucosal pH. Cardiac output was maintained in the animals receiving the saline infusion. By 2 hrs, pulmonary arterial pressure had decreased but was still notably higher than baseline. However, by this time, MAP had decreased to < or =60 mm Hg. L-NAME administration restored MAP to its baseline value but resulted in worsening pulmonary hypertension, increased right ventricular volumes, and decreased cardiac output, compared with the saline group. Three animals that received L-NAME died of right ventricular failure. We did not observe any evidence of left ventricular dysfunction with increased left ventricular afterload. Moreover, the restoration of MAP with L-NAME infusion did not correct gastric mucosal acidosis. No changes were noted in the time-control group. Occlusion of the thoracic aorta increased MAP but did not change cardiac output. This finding demonstrates that increases in left ventricular afterload of the magnitude seen with the infusion of L-NAME do not lead to decreases in cardiac output.

CONCLUSION

The decrease in cardiac output after nitric oxide synthase inhibition in endotoxemia is due to increased right ventricular afterload and not to left ventricular afterload.