Michele D'Alto

Exercise stress echocardiography for the study of the pulmonary circulation.

Exercise stress tests have been used for the diagnosis of pulmonary hypertension, but with variable protocols and uncertain limits of normal. The pulmonary haemodynamic response to progressively increased workload and recovery was investigated by Doppler echocardiography in 25 healthy volunteers aged 19–62 yrs (mean 36 yrs). Mean pulmonary artery pressure (P̄pa) was estimated from the maximum velocity of tricuspid regurgitation. Cardiac output (Q) was calculated from the aortic velocity-time integral. Slopes and extrapolated pressure intercepts of P̄pa–Q plots were calculated after using the adjustment of Poon for individual variability. A pulmonary vascular distensibility α was calculated from each P̄pa–Q plot to estimate compliance. P̄pa increased from 14±3 mmHg to 30±7 mmHg, and decreased to 19±4 mmHg after 5 min recovery. The slope of P̄pa–Q was 1.37±0.65 mmHg·min−1·L−1 with an extrapolated pressure intercept of 8.2±3.6 mmHg and an α of 0.017±0.018 mmHg−1. These results agree with those of previous invasive studies. Multipoint P̄pa–Q plots were well described by a linear approximation, from which resistance can be calulated. We conclude that exercise echocardiography of the pulmonary circulation is feasible and provides realistic resistance and compliance estimations. Measurements during recovery are unreliable because of rapid return to baseline.

Exercise Stress Echocardiography of the Pulmonary Circulation: Limits of Normal and Sex Differences

BACKGROUND Exercise stress echocardiography has not been recommended in the diagnostic workup of pulmonary hypertension because of insufficient certainty about feasibility and limits of normal. METHODS Doppler echocardiography pulmonary hemodynamic measurements were performed at a progressively increased workload in 56 healthy male and 57 healthy female volunteers aged 19 to 63 years. Mean pulmonary artery pressure (mPAP) was estimated from the maximal tricuspid regurgitation jet velocity. Cardiac index was calculated from the left ventricular outflow velocity-time integral. Pulmonary vascular distensibility a index, the percentage change of vessel diameter permm Hg of mPAP, was calculated from multipoint mPAP-cardiac output (CO) plots. RESULTS Peak exercise at 175 ±50 W was associated with an mPAP of 33±7 mm Hg and a CO of 18 ±5 L/min. The slope of mPAP-CO relationships was 1.5 ± 0.5 mm Hg/L/min, and the distensibility coefficient ( α ) was 1.3%± 1.0%/mm Hg. Maximal workload and cardiac index were higher in men than in women ( P , .05), but mPAP-cardiac index relationships were not different. However,women had a higher a (1.6%± 1.3%/mm Hg vs 1.1%± 0.6%/mm Hg, P < .05). The average mPAP-cardiac index slope was higher and a lower in subjects ≥50 years old. Upper limits of normal of mPAP at exercise were 34 mm Hg at a CO , 10 L/min, 45 mm Hg at a CO <20 L/min, and 52 mm Hg at a CO<30 L/min. These values are in keeping with previously reported invasive measurements. CONCLUSIONS Exercise stress echocardiography of the pulmonary circulation is feasible and allows for fl ow-corrected definition of upper limits of normal. Women have a more distensible pulmonary circulation.

Accuracy and precision of echocardiography versus right heart catheterization for the assessment of pulmonary hypertension

BACKGROUND Echocardiographic studies have contributed to progress in the understanding of the pathophysiology of the pulmonary circulation and have been shown to be useful for screening for and prognostication of pulmonary hypertension, but are considered unreliable for the diagnosis of pulmonary hypertension. We explored this apparent paradox with rigorous Bland and Altman analysis of the accuracy and the precision of measurements collected in a large patient population. METHODS A total of 161 patients referred for a suspicion of pulmonary hypertension were prospectively evaluated by a Doppler echocardiography performed by dedicated cardiologists within 1 h of an indicated right heart catheterization. RESULTS Nine of the patients (6%) were excluded due to an insufficient signal quality. Of the remaining 152 patients, 10 (7%) had no pulmonary hypertension and most others had either pulmonary arterial hypertension (36%) or pulmonary venous hypertension (40%) of variable severities. Mean pulmonary artery pressure, left atrial pressure and cardiac output were nearly identical at echocardiography and catheterization, with no bias and tight confidence intervals, respectively ± 3 mm Hg, ± 5 mm Hg and ± 0.3 L/min. However, the ± 2SD limits of agreement were respectively of + 19 and - 18 mm Hg for mean pulmonary artery pressure, + 8 and - 12 mm Hg for left atrial pressure and + 1.8 and - 1.7 L/min for cardiac output. CONCLUSIONS Doppler echocardiography allows for accurate measurements of the pulmonary circulation, but with moderate precision, which explains why the procedure is valid for population studies but cannot be used for the individual diagnosis of pulmonary hypertension.

Original ResearchPulmonary Vascular DiseaseExercise Stress Echocardiography of the Pulmonary Circulation: Limits of Normal and Sex Differences

BACKGROUND Exercise stress echocardiography has not been recommended in the diagnostic workup of pulmonary hypertension because of insufficient certainty about feasibility and limits of normal. METHODS Doppler echocardiography pulmonary hemodynamic measurements were performed at a progressively increased workload in 56 healthy male and 57 healthy female volunteers aged 19 to 63 years. Mean pulmonary artery pressure (mPAP) was estimated from the maximal tricuspid regurgitation jet velocity. Cardiac index was calculated from the left ventricular outflow velocity-time integral. Pulmonary vascular distensibility a index, the percentage change of vessel diameter permm Hg of mPAP, was calculated from multipoint mPAP-cardiac output (CO) plots. RESULTS Peak exercise at 175 ±50 W was associated with an mPAP of 33±7 mm Hg and a CO of 18 ±5 L/min. The slope of mPAP-CO relationships was 1.5 ± 0.5 mm Hg/L/min, and the distensibility coefficient ( α ) was 1.3%± 1.0%/mm Hg. Maximal workload and cardiac index were higher in men than in women ( P , .05), but mPAP-cardiac index relationships were not different. However,women had a higher a (1.6%± 1.3%/mm Hg vs 1.1%± 0.6%/mm Hg, P < .05). The average mPAP-cardiac index slope was higher and a lower in subjects ≥50 years old. Upper limits of normal of mPAP at exercise were 34 mm Hg at a CO , 10 L/min, 45 mm Hg at a CO <20 L/min, and 52 mm Hg at a CO<30 L/min. These values are in keeping with previously reported invasive measurements. CONCLUSIONS Exercise stress echocardiography of the pulmonary circulation is feasible and allows for fl ow-corrected definition of upper limits of normal. Women have a more distensible pulmonary circulation.

Long term effects of bosentan treatment in adult patients with pulmonary arterial hypertension related to congenital heart disease (Eisenmenger physiology) : safety, tolerability, clinical, and haemodynamic effect

Background: Oral bosentan is an established treatment for pulmonary arterial hypertension (PAH). Objective: To evaluate safety, tolerability, and clinical and haemodynamic effects of bosentan in patients with PAH related to congenital heart disease (CHD). Patients: 22 patients with CHD related PAH (8 men, 14 women, mean (SD) age 38 (10) years) were treated with oral bosentan (62.5 mg×2/day for the first 4 weeks and then 125 mg×2/day). Main outcome measures: Clinical status, liver enzymes, World Health Organisation (WHO) functional class, resting oxygen saturations and 6-min walk test (6MWT) were assessed at baseline and at 1, 3, 6, and 12 months. Haemodynamic evaluation with cardiac catheterisation was performed at baseline and at 12 month follow-up. Results: 12 patients had ventricular septal defect, 5 atrioventricular canal, 4 single ventricle, and 1 atrial septal defect. All patients tolerated bosentan well. No major side effects were seen. After a year of treatment, an improvement was seen in WHO functional class (2.5 (0.7) v 3.1 (0.7); p<0.05), oxygen saturation at rest (87 (6%) v 81 (9); p<0.001), heart rate at rest (81 (10) v 87 (14) bpm; p<0.05), distance travelled in the 6MWT (394 (73) v 320 (108) m; p<0.001), oxygen saturation at the end of the 6MWT (71 (14) v 63 (17%); p<0.05), Borg index (5.3 (1.8) v 6.5 (1.3); p<0.001), pulmonary vascular resistances index (14 (9) v 22 (12) WU m2; p<0.001), systemic vascular resistances index (23 (11) v 27 (10) WU.m2; p<0.01), pulmonary vascular resistances index/systemic vascular resistances index (0.6 (0.5) v 0.9 (0.6); p<0.05); pulmonary (4.0 (1.3) v 2.8 (0.9) l/min/m2; p<0.001) and systemic cardiac output (4.2 (1.4) v 3.4 (1.1) l/min/m2; p<0.05). Conclusions: Bosentan was safe and well tolerated in adults with CHD related PAH during 12 months of treatment. Clinical status, exercise tolerance, and pulmonary haemodynamics improved considerably.

Pulmonary arterial hypertension associated with congenital heart disease

Pulmonary arterial hypertension (PAH) is a common complication of congenital heart disease (CHD), with most cases occurring in patients with congenital cardiac shunts. In patients with an uncorrected left-to-right shunt, increased pulmonary pressure leads to vascular remodelling and dysfunction, resulting in a progressive rise in pulmonary vascular resistance and increased pressures in the right heart. Eventually, reversal of the shunt may arise, with the development of Eisenmengers syndrome, the most advanced form of PAH-CHD. The prevalence of PAH-CHD has fallen in developed countries over recent years and the number of patients surviving into adulthood has increased markedly. Today, the majority of PAH-CHD patients seen in clinical practice are adults, and many of these individuals have complex disease or received a late diagnosis of their defect. While there have been advances in the management and therapy in recent years, PAH-CHD is a heterogeneous condition and some subgroups, such as those with Downs syndrome, present particular challenges. This article gives an overview of the demographics, pathophysiology and treatment of PAH-CHD and focuses on individuals with Downs syndrome as an important and challenging patient group.

Inappropriate exercise-induced increase in pulmonary artery pressure in patients with systemic sclerosis

Background Recent data show that there is an unexpectedly high prevalence of ‘inappropriate’ pulmonary responses to exercise among patients with systemic sclerosis (SS). However, no consensus exists as to which threshold of pulmonary artery systolic pressure (PASP) can be considered diagnostically relevant. Aim To evaluate pulmonary vascular reserve and right ventricular function changes induced by exercise in SS patients without overt pulmonary arterial hypertension. Methods and results The study enrolled 172 consecutive SS patients in NYHA class I–II, with a peak tricuspid regurgitant jet velocity at echocardiography not greater than 3 m/s, and 88 control subjects. Echocardiography was performed at rest and at the end of a maximal exercise test. SS patients showed a higher exercise-induced PASP than control subjects (36.9±8.7 vs 25.9±3.3 mm Hg, p=0.00008). The response to effort was higher in the presence of moderate interstitial lung disease (39.7±9.3 vs 36.0±8.4 mm Hg, p=0.016) or subclinical left ventricular diastolic dysfunction (42.3±5.8 vs 37.0±8.6 mm Hg, p=0.015). In control subjects, PASP values were normally distributed at rest and after exercise. In SS patients, the distribution was normal at rest but bimodal after exercise, with a second peak at 52.2 mm Hg including 13% of the total SS population. Patients in this subgroup showed subtle abnormalities of right ventricular function at rest and, most importantly, a blunted increase in right ventricular systolic function with exercise. Conclusion Exercise echocardiography may identify a subset of SS patients with an inappropriate exercise-induced increase in PASP and early signs of right ventricular dysfunction.

Bosentan–sildenafil association in patients with congenital heart disease-related pulmonary arterial hypertension and Eisenmenger physiology

OBJECTIVES The aim of the present study was to evaluate the safety, tolerability, clinical and haemodynamic impact of add-on sildenafil in patients with congenital heart disease (CHD)-related pulmonary arterial hypertension (PAH) and Eisenmenger physiology after failure of oral bosentan therapy. METHODS Thirty-two patients with CHD-related PAH (14 male, mean age 37.1 ± 13.7 years) treated with oral bosentan underwent right heart catheterization (RHC) for clinical worsening. After RHC, all patients received oral sildenafil 20mg thrice daily in addition to bosentan. Clinical status, resting transcutaneous oxygen saturation (SpO(2)), 6-minute walk test (6MWT), serology and RHC were assessed at baseline (before add-on sildenafil) and after 6 months of combination therapy. RESULTS Twelve patients had ventricular septal defect, 8 atrio-ventricular canal, 6 single ventricle, and 6 atrial septal defect. Twenty-eight/32 had Eisenmenger physiology and 4 (all with atrial septal defect) did not. All patients well tolerated combination therapy. After 6 months of therapy, an improvement in clinical status (WHO functional class 2.1 ± 0.4 vs 2.9 ± 0.3; P=0.042), 6-minute walk distance (360 ± 51 vs 293 ± 68 m; P=0.005), SpO(2) at the end of the 6MWT (72 ± 10 vs 63 ± 15%; P=0.047), Borg score (2.9 ± 1.5 vs 4.4 ± 2.3; P=0.036), serology (pro-brain natriuretic peptide 303 ± 366 vs 760 ± 943 pg/ml; P=0.008) and haemodynamics (pulmonary blood flow 3.4 ± 1.0 vs 3.1 ± 1.2l/min/m(2), P=0.002; pulmonary vascular resistances index 19 ± 9 vs 24 ± 16 WU/m(2), P=0.003) was observed. CONCLUSIONS Addition of sildenafil in adult patients with CHD-related PAH and Eisenmenger syndrome after oral bosentan therapy failure is safe and well tolerated at 6-month follow-up, resulting in a significant improvement in clinical status, effort SpO(2), exercise tolerance and haemodynamics.

Right ventricular myocardial activation delay in adult patients with right bundle branch block late after repair of Tetralogy of Fallot

Electromechanical interaction, with prolonged QRS duration due to right ventricular (RV) overload, has been described as a predictor of unfavorable outcome in patients late after correction of Tetralogy of Fallot (TOF). Aim of our study was to evaluate myocardial function and activation delay of both left and right ventricles in TOF patients. Doppler echo, treadmill test and pulsed Tissue Doppler (TD) were performed in 25 healthy subjects and in 30 adult patients who had undergone surgery for TOF, all with right bundle branch block on ECG. Exclusion criteria were evidence of residual pulmonary either stenosis or regurgitation. By use of TD, the level of both LV mitral and RV tricuspid annulus were measured: systolic (Sm), early- and late-diastolic (Em and Am) regional peak velocities. The indexes of myocardial systolic activation were calculated: precontraction time (PCTm) and interventricular activation delay (InterV-del) (difference of PCTm between RV and LV segments). The two groups were comparable for LV diameters and for Doppler indexes, while QRS duration was prolonged and RV end-diastolic diameter was increased in TOF. By TD analysis, only at the level of tricuspid annulus TOF patients had lower Sm and Em, and increased RV PCTm ( p<0.001 ) and InterV-del ( p<0.0001 ), even after adjustment for heart rate (HR) and QRS duration. By treadmill test, TOF showed reduced cardiac functional reserve. In seven patients non-sustained ventricular tachycardia was documented during physical effort. By multivariate analysis, RV Em ( p<0.001 ), and InterV-del ( p<0.01 ) were independently associated to maximal workload at peak effort. The same InterV-del was an independent determinant of risk of ventricular arrhythmias during effort ( p<0.01 ). A cut-off point of Em peak velocity of tricuspid annulus <0.13 m/s at rest showed a sensitivity of 91% and a specificity of 88% in identifying TOF patients with submaximal exercise test. A cut-off point of InterV-del >55 ms showed 87% sensitivity and 88% specificity to detect increased risk of ventricular arrhythmias during effort. In TOF patients, TD analysis at rest may be taken into account as a non-invasive and easy-repeatable tool to predict cardiac performance during physical effort, and to select subgroups of patients at increased risk of ventricular arrhythmias.

Aortic and left ventricular remodeling in patients with bicuspid aortic valve without significant valvular dysfunction: A prospective study

BACKGROUND Bicuspid aortic valve (BAV) represents the most common cardiac congenital malformation in the adult age. It is frequently associated with dilatation, aneurysm and dissection of the ascending aorta. The purpose of the following study was to evaluate in patients with BAV: 1) the elastic properties of the ascending aorta, 2) the mechanical function of the left ventricle and 3) stiffness, elasticity and strain of the epi-aortic vessels wall. METHODS Forty BAV patients (28M/12F; age 20.9 ± 4.7 years; range 17-26) with no or mild valvular impairment were recruited with 40 control subjects (25M/15F; age 23.4 ± 3.4 years; range 15-31) matched for age, gender and body surface area (BSA). Aortic strain, aortic distensibility (AoDIS) and aortic stiffness index (AoSI) were derived. Left ventricular strain was acquired. Elastic properties of epi-aortic vessels were evaluated. RESULTS BAVs vs. controls had increased systolic and diastolic aortic diameters (p<0.001). Aortic strain (%) was lower in BAVs than in controls (8.3 ± 3.6 vs. 11.2 ± 2.6; p<0.001) as well as AoDIS (10(-6)cm(2)dyn(-1)) (6.5 ± 2.8 vs. 8.8 ± 2.9; p=0.002), while AoSI was greater in BAVs (6.4 ± 3.5 vs. 3.9 ± 1.2; p<0.001). Both AoDIS and aortic strain were related to aortic size in BAVs and controls. Left ventricular longitudinal (p=0.01), circumferential (p=0.01) and radial (p<0.001) strain (%) were lower in BAVs. No significant differences were found in elastic properties of epi-aortic vessels. CONCLUSIONS Bicuspid aortic valve is associated with an increased aortic stiffness and with a reduction of the aortic and left ventricular deformation properties. Epi-aortic vessels do not seem to be interested by the disease. The use of an echocardiographic method that can estimate the degree of aortic and left ventricular remodeling can provide great benefits in the selection of patients with BAV to be treated and in determining the time for beginning drug therapy.