Rationale, design and methodology of APPROACH-IS II: International study of patient-reported outcomes and frailty phenotyping in adults with congenital heart disease.

BACKGROUND: In recent years, patient-reported outcomes (PROs) have received increasing prominence in cardiovascular research and clinical care. An understanding of the variability and global experience of PROs in adults with congenital heart disease (CHD), however, is still lacking. Moreover, information on epidemiological characteristics and the frailty phenotype of older adults with CHD is minimal. The APPROACH-IS II study was established to address these knowledge gaps. This paper presents the design and methodology of APPROACH-IS II. METHODS/DESIGN: APPROACH-IS II is a cross-sectional global multicentric study that includes Part 1 (assessing PROs) and Part 2 (investigating the frailty phenotype of older adults). With 53 participating centers, located in 32 countries across six continents, the aim is to enroll 8000 patients with CHD. In Part 1, self-report surveys are used to collect data on PROs (e.g., quality of life, perceived health, depressive symptoms, autonomy support), and explanatory variables (e.g., social support, stigma, illness identity, empowerment). In Part 2, the cognitive functioning and frailty phenotype of older adults are measured using validated assessments. DISCUSSION: APPROACH-IS II will generate a rich dataset representing the international experience of individuals in adult CHD care. The results of this project will provide a global view of PROs and the frailty phenotype of adults with CHD and will thereby address important knowledge gaps. Undoubtedly, the project will contribute to the overarching aim of improving optimal living and care provision for adults with CHD.

[Electrocardiographic findings related to young Senegalese basketball players]. / Aspects électrocardiographiques de jeunes basketteurs sénégalais.

Intensive and prolonged practice of sport can lead to cardiovascular and electrocardiographic changes. The purpose of this study was to describe the electrocardiographic changes in some young black Senegalese players practicing competitive basketball. We conducted a prospective descriptive analysis of surface electrocardiogram (ECG) findings related to young Senegalese Black players practicing competitive basketball. The study involved 40 young basketball players, 20 girls and 20 boys, whose average age was 17 ± 0.86 years (ranging from 17 to 19 years) and 15 ± 1.56 years (ranging from 13 to 18 years) respectively. Heart rate was lower among boys, 59 beats ± 9 beats (ranging from 42 to 85) than among girls 73 beats/ min ± 11 beats (ranging from 50 to 95) (p = 0.0004). The following features have been observed: repolarization abnormalities such as T-wave inversion V1-V4 in 3 cases (7.5%), right ventricular hypertrophy in 1 case (2.5%), right axis deviation (QRS axis) in 1 case (2.5%). Intensive and prolonged practice of basketball leads to electrocardiographic changes in the young black Senegalese players.

Usefulness of the right parasternal view and non-imaging continuous-wave Doppler transducer for the evaluation of the severity of aortic stenosis in the modern area.

AIMS: Evaluation of the severity of the aortic stenosis (AS) is based on echocardiographic assessment of peak velocity/mean transaortic pressure gradient (MPG) by continuous-wave Doppler and calculation of the aortic valve area (AVA) using the continuity equation. Pioneering echocardiographic studies have shown that MPG should be measured from the apical and right parasternal views using non-imaging continuous-wave Doppler transducer (NI-CWD). Nowadays, ultrasound systems are often sold without NI-CWD due, at least partially, to the improvement of two-dimensional continuous-wave Doppler transducers (2D-CWD). Whether this evolution translated into misevaluation of AS severity was uncertain. Our aim was to evaluate the additional diagnostic value of the use of NI-CWD and the right parasternal view for the evaluation of AS severity in the modern area. METHODS AND RESULTS: We prospectively evaluated MPG and AVA using the 2D-CWD (apical view) and the NI-CWD (right parasternal view) in 100 patients (78 +/- 5 years, 65% male) consecutively enrolled in an ongoing prospective study. Aortic stenosis severity was graded as mild (AVA > or = 1.5 cm(2)), moderate (1-1.5 cm(2)), or severe (AVA < 1 cm(2)). Misclassification was defined as at least a one grade difference and DeltaAVA > 0.15 cm(2) (twice the intra-observer variability). Feasibility of the 2D-CWD was 100%, MPG 20 +/- 13 mmHg, and AVA 1.52 +/- 0.45 cm(2). Fifty-three per cent had a mild AS, 34% a moderate AS, and 13% a severe AS. Using the NI-CWD, feasibility was 85%, MPG 25 +/- 16 mmHg, AVA 1.33 +/- 0.41 cm(2) (both P < 0.005 compared with 2D-CWD). Thirty-five per cent (n = 30) had a mild AS, 46% (n = 39) a moderate AS, and 19% (n = 16) a severe AS. Using only the 2D-CWD and the apical view, 21 patients (21%) would have been misclassified: 17 as mild instead of moderate AS and 4 as moderate instead of severe AS. In those misclassified patients, MPG was 9 +/- 6 mmHg higher with the NI-CWD and 33% had an MPG difference >10 mmHg. CONCLUSION: The use of the NI-CWD and the right parasternal view must be performed to evaluate AS severity, especially in case of discrepancy between symptoms and AS severity or for precise evaluation of AS progression.

[Poorly tolerated atrial tachycardia in a newborn: a case study]. / La tachycardie atriale mal tolérée du nouveau-né: à propos d'un cas.

Poorly tolerated cardiac rhythm disorders in the newborn are a real emergency requiring early and adequate management. We here report the case of 15-day old newborn with atrial tachycardia associated with acute heart failure requiring electrical cardioversion.

Percutaneous transmitral balloon commissurotomy using a single balloon with arteriovenous loop stabilisation: an alternative when there is no Inoue balloon.

BACKGROUND: The Inoue balloon technique is the standard technique for mitral valve balloon commissurotomy at this stage. However, the hardware for this technique is expensive and may not always be available in resource-limited settings. OBJECTIVE: This article reports our experience with percutaneous transmitral balloon commissurotomy using a single balloon (Nucleus) with arteriovenous loop stabilisation. METHOD: Eleven young patients, aged 12-26 years and weighing 23-48 kg, underwent transmitral balloon commissurotomy using the described technique at our centre from April to May 2014. RESULTS: Mean fluoroscopy time was 22.6 ± 6.4 min (18.5- 30.0). Mean transmitral gradient decreased from 24.1 ± 5.9 (16-35) to 6.6 ± 3.8 (3-14) mmHg, as measured on transoesophageal echocardiography. Mean mitral valve area increased from 0.69 ± 0.13 cm2 (range 0.5-0.9) before dilation to 1.44 ± 0.25 cm2 (1.1-1.9) after dilation (p < 0.001). Mean estimated pulmonary artery systolic pressure decreased from 110.0 ± 35 mmHg (75-170) before dilation to 28.0 ± 14.4 mmHg (range 10-60) after dilation. CONCLUSION: Our modified Nucleus balloon technique for mitral valve dilation in young patients with mitral stenosis is effective and safe. The technique differs from other over-the-wire techniques in that it avoids placing stiff wire in the left ventricle. It also offers better balloon stability and control owing to the arteriovenous loop. This technique may be easier for use by paediatric interventionists who might not be familiar with the Inoue balloon technique.

Difference Between Persistent Aneurysm, Regressed Aneurysm, and Coronary Dilation in Kawasaki Disease: An Optical Coherence Tomography Study.

BACKGROUND: Coronary artery (CA) aneurysms are a serious complication of Kawasaki disease (KD). Conventional imaging techniques often described segments with regressed aneurysms as normal, whereas studies have shown significant endothelial dysfunction. METHODS: KD patients with aneurysms scheduled for routine coronary angiography underwent optical coherence tomography (OCT) imaging between 2013 and 2016. Microstructural coronary changes were compared between normal CA segments and those with dilation, regressed aneurysms, and persistent aneurysms. RESULTS: OCT was performed on 33 patients aged 12.0 ± 5.4 years, 8.5 ± 5.4 years after KD diagnosis. Of the 79 segments analyzed, 25 had persistent aneurysms, 22 regressed aneurysms, 11 CA dilation, and 21 no CA involvement. Intimal thickness was 489 ± 173 µm, 304 ± 158 µm, 102 ± 68 µm, and 63 ± 29 µm, respectively (P < 0.001). There was a linear correlation between the maximum aneurysm size and the intimal thickness, as well as coronary dimension at the time of OCT. Fibrosis (54 segments, 68%) and cellular infiltration (22 segments, 28%) were found more often in segments with CA involvement, but also those without (P = 0.01; P = 0.02). Destruction of the media (34 segments, 43%), calcifications (6 segments, 8%), neovascularization (18 segments, 23%), and white thrombi (8 segments, 10%) were found almost exclusively in segments with a history of aneurysms. CONCLUSIONS: Intimal hyperplasia, fibrosis, and cellular infiltration were found in all categories of CA involvement, whereas calcification, destruction of the media, neovascularization, and white thrombi were found essentially only in segments with saccular or fusiform aneurysms. Prospective studies with outcome correlations are needed to see if this is associated with an increased risk of late adverse events.

[Heart failure with normal heart revealing complex arteriovenous malformation of the lower limb in a child: case study and literature review]. / Insuffisance cardiaque sur cœur normal révélant une malformation artériole-veineuse complexe du membre inferieur chez un enfant: à propos d'une observation et revue de la littérature.

Arteriovenous malformations (AVM) are congenital high-flow vascular defects. They are very rare in children. Diagnosis and treatment are often delayed due to their atypical place of occurrence and to their variable clinical manifestations. We report the case of a child treated at the National Centre Hospitalier Albert Royer Children, Dakar. A boy aged 9 years was referred from a health facility in rural areas for the treatment of heart failure. Admission clinical examination showed impaired general condition, global heart failure syndrome and voluminous right warm inguinocrural mass extended to the right abdominal wall (iliac fossa and right flank), with poorly defined limits. Auscultation of this mass showed a thrill and diffuse murmur. Cardiac ultrasound showed severe pulmonary arterial hypertension (PAH) with extensive impairement of the heart cavities, without cardiac structural involvement. The diagnosis of AVM was confirmed by doppler ultrasound of the mass complemented by angiography scan. They showed multiple arteriovenous fistulas within the mass. The diagnosis of complex stage IV AVM (according to Schöbinger classification) of the root of the right thigh was retained. Clinical treatment of heart failure was based on furosemide, spironolactone and captopril to obtain hemodynamic stabilization before possible surgical procedure. Arteriovenous malformations of the limbs, in particular of the proximal end of the lower limb in children are still largely unknown, hence frequent diagnostic errors and delays. Their evolution is unpredictable requiring early diagnosis and careful monitoring involving multidisciplinary interaction between pediatrics, surgeons and radiologists.

[Poorly tolerated broad QRS complex tachycardia in a newborn]. / Une tachycardie à QRS large mal tolérée chez un nourrisson.

Poorly tolerated broad QRS complex tachycardia in a newborn poses problems with its diagnosis and emergency management. We report the case of a 35-day-old newborn with broad QRS complex tachycardia admitted because of cardiocirculatory distress. Doppler echocardiography showed morphologically normal heart. The patient received a loading dose of amiodarone but it didn't attenuate tachycardia. Normal sinus rhythm was restored after cardioversion through Lifeline semi-automatic external defibrillator. Maintenance therapy was based on oral amiodarone. The patient had normal sinus rhythm at 03 months of follow-up.

Percutaneous recanalization of totally occluded coarctation of the aorta in children using Brockenbrough needle and covered stents.

Percutaneous treatment of totally occluded coarctation of the aorta has been reported predominantly in adults. The success and challenges of this procedure in children is reported in few patients. We report an outcome of percutaneous treatment of three children with completely occluded coarctation of the aorta. The age range was 9-14 years. All the patients had upper limb hypertension. One case had severe left ventricular dysfunction. In all cases, a pediatric Brockenbrough needle and a covered stent were implanted. Recanalization and implantation of a covered stent was successful in all patients. One of these patients developed transient postcoarctectomy syndrome. Percutaneous recanalization of totally occluded coarctation of the aorta using Brockenbrough needle and a covered stent in children is feasible and effective.

A graph-based approach for spatio-temporal segmentation of coronary arteries in X-ray angiographic sequences.

The segmentation and tracking of coronary arteries (CAs) are critical steps for the computation of biophysical measurements in pediatric interventional cardiology. In the literature, most methods are focused on either segmenting the vessel lumen or on tracking the vessel centerline. However, they do not simultaneously combine the segmentation and tracking of a specific CA. This paper introduces a novel algorithm for CA segmentation and tracking from 2D X-ray angiography sequences. The proposed algorithm is based on the Temporal Vessel Walker (TVW) segmentation method, which combines graph-based formulation and temporal priors. Moreover, superpixel groups are used by TVW as image primitives to ensure a better extraction of the CA. The proposed algorithm, TVW with superpixels (SP-TVW), returns an accurate result to segment and track the artery along the angiogram. Quantitative results over 12 sequences of young patients show the accuracy of the proposed framework. The results return a mean recall of 84% in the dataset. In addition, the proposed method returned a Dice index of 70% in segmenting and tracking right coronary arteries and circumflex arteries. The performance of the proposed method surpasses the existing polyline method in tracking the centerline of CA with a more precise localization of the centerline, resulting in a smaller distance error of 0.23mm compared to 0.94mm.

[The prevalence of symptomatic infantile heart disease at Louga Regional Hospital, Senegal]. / Prevalence des cardiopathies infantiles symptomatiques au Centre Hospitalier Régional de Louga, Senegal.

The management of congenital or acquired infantile heart diseases in sub-Saharan African countries still presents problems, particularly with diagnosis and access to surgical treatment. Our objectives were to describe the heart diseases observed in the paediatric setting of the Louga Regional Hospital (LRH) and report their short-term evolution. In the study period from 1 July 2009 to 31 December 2012, 82 children out of 18,815 presented with heart disease, which was a prevalence of 4.3/1,000. There was a female predominance, with a ratio of 1.2. The most frequent presenting conditions were dyspnoea at 47.5%, followed by heart murmurs at 35.3%, and congestive heart failure at 13.4%. Congenital heart diseases were the most frequent, representing 69.5% of the cases, followed by acquired heart diseases at 29.3%, and mixed-type cases at 1.2%. The most frequently encountered congenital heart diseases were ventricular septal defect (24.4%), followed by atrioventricular septal defect (12.2%), tetralogy of Fallot (9.8%) and patent ductus arteriosus (7.3%). Acquired heart disease was represented by rheumatic heart disease, found in 25.6% of the cases, and tuberculous pericarditis in 3.7%. The mortality rate was high, with 20 children dying (24.4%) during the study period. Only 13 out of 82 patients (15.9%) were operable and surgery was carried out in France, courtesy of the association Humanitarian Mécénat Chirurgie Cardiaque. Infantile heart diseases were therefore not very frequent in the paediatric unit of Louga Regional Hospital. However, congenital heart disease was more frequent than acquired heart disease, with a high mortality rate. Access to surgery remains limited.

Coronary Wall Structural Changes in Patients With Kawasaki Disease: New Insights From Optical Coherence Tomography (OCT).

BACKGROUND: Coronary artery aneurysms (CAA) are serious complications of Kawasaki disease (KD). Optical coherence tomography (OCT) is a high-resolution intracoronary imaging modality that characterizes coronary artery wall structure. The purpose of this work was to describe CAA wall sequelae after KD. METHODS AND RESULTS: KD patients scheduled for routine coronary angiography underwent OCT imaging between March 2013 and August 2014. Subjects' clinical courses, echocardiography, and coronary angiography examinations were reviewed retrospectively. OCT was performed in 18 patients aged 12.4±5.5 years, 9.0±5.1 years following onset of KD. Of those, 14 patients (77.7%) had a history of CAA (7 with giant CAA and 7 with regressed CAA at time of OCT). Intracoronary nitroglycerin was given to all patients (88.4±45.5 µg/m(2)). Mean radiation dose was 10.9±5.2 mGy/kg. One patient suffered from a transitory uneventful vasospasm at the site of a regressed CAA; otherwise no major procedural complications occurred. The most frequent abnormality observed on OCT was intimal hyperplasia (15 patients, 83.3%) seen at both aneurysmal sites and angiographically normal segments amounting to 390.8±166.0 µm for affected segments compared to 61.7±17 µm for unaffected segments (P<0.001). Disappearance of the media, and presence of fibrosis, calcifications, macrophage accumulation, neovascularization, and white thrombi were seen in 72.2%, 77.8%, 27.8%, 44.4%, and 33.3% of patients. CONCLUSIONS: In this study, OCT proved safe and insightful in the setting of KD, with the potential to add diagnostic value in the assessment of coronary abnormalities in KD. The depicted coronary structural changes correspond to histological findings previously described in KD.

A case of pericardial tuberculoma presenting as a left anterior chest wall mass.

INTRODUCTION: Tuberculosis (TB) can present both in its pulmonary or extra-pulmonary forms. Cardiac tuberculoma previously described only after autopsy is continuously seen with the advent of more advanced imaging modalities. CASE REPORT: A 23-year-old male with a four month history of a progressively increasing left anterior thoracic wall mass of 5 cm in diameter was referred from oncology for clinical re-evaluation and for echocardiography. Systemic examination was essentially normal. Transthoracic and trans-oesophageal echocardiography showed the presence of a pericardial mass around the right atrioventricular junction. Thoracic CT scan showed an anterior mass in left chest wall extending to the pericardium and also the presence of mediastinal lymphadenopathy. Mantoux test was positive and histological examination of tissue biopsy confirmed the presence of TB. However, blood tests and culture of aspirated purulent fluid were unyielding. A diagnosis of pericardial tuberculoma with mediastinal and parietal extension was made and patient was successfully treated with standard anti-TB chemotherapy. DISCUSSION: The possible differential diagnoses for chest wall tumors are varied and a high degree of suspicion is needed to diagnose cardiac tuberculoma especially in endemic regions. Imaging though helpful in morphological description cannot make precise diagnosis. The diagnosis depends on histological and culture studies. There is usually a good evolution with anti-TB treatment. CONCLUSION: In an era of an increasing number of acquired immune-compromised patients, and with increasing number of diagnoses of tuberculosis, a diagnosis of cardiac tuberculoma should be considered in patients presenting with a thoracic wall mass.

Combination of left ventricular noncompaction and partial atrioventricular canal defect in a 21-year-old male: a case report.

INTRODUCTION: Left ventricular noncompaction (LVNC) is classified as a genetic cardiomyopathy characterized by a progressive systolic dysfunction. It may occur alone or in association with congenital cardiac anomalies. The combination of left ventricular noncompaction with partial atrioventricular canal defect is rare and has not, to our knowledge, been described previously. CASE PRESENTATION: A 21-year-old male who traveled to our center from a neighboring country presented with signs of heart failure. Transthorarcic echocardiography showed prominent trabeculations in the left ventricle predominantly in the left ventricle involving the apical lateral and mid anterolateral segments associated with a partial atrioventricular canal defect. There was a biventricular systolic dysfunction. There was good response to medical treatment. CONCLUSION: This case stresses the importance of maintaining a high degree of suspicion for this rare cardiomyopathy and the need to systematically look for other associated anomalies in order to institute proper short- and long-term managements.

Determinants of regurgitant volume in mitral regurgitation: contrasting effect of similar effective regurgitant orifice area in functional and organic mitral regurgitation.

BACKGROUND: Quantitative assessment of the severity of mitral regurgitation (MR) is based on the calculation of the effective regurgitant orifice (ERO), a measure of lesion severity, and of the regurgitant volume (RVol), a measure of left ventricular volume overload. We aimed at evaluating the determinants of RVol in both organic (OMR) and functional mitral regurgitation (FMR). METHODS AND RESULTS: MR severity was quantitatively assessed using the proximal isovelocity surface area (PISA) method in 240 patients, 142 with OMR and 98 patients with FMR. By definition, ERO and RVol were strongly correlated both in patients with OMR and FMR (both R = 0.90, P < 0.0001) but the slopes of the regression lines were significantly different (P < 0.0001). This difference remained significant in patients with elevated systolic pulmonary artery pressure (SPAP > 40 mmHg, P < 0.0001) but not in patients with normal SPAP (≤40 mmHg, P = 0.09). In multivariate analysis, independent determinants of RVol were ERO (P < 0.0001), MR mechanism (FMR/OMR) (P = 0.0003) and SPAP (P = 0.03). In patients with elevated SPAP, ERO (P < 0.0001), left ventricular ejection fraction (LVEF) (P = 0.03), and MR mechanism (P = 0.03) were independently associated with RVol, whereas in patients with normal SPAP, ERO (P < 0.0001) was the only independent determinant of RVol. CONCLUSION: In the present study, we evaluated the contrasting effect of similar lesion severity in OMR and FMR and showed that similar ERO were associated with lower RVol in FMR compared with OMR. The regurgitant volume is the result of complex interactions of anatomic lesions, LVEF, and SPAP and our results highlight the importance of taking into account these parameters when interpreting RVol values in clinical practice, especially in FMR.

Comparison of semiquantitative and quantitative assessment of severity of aortic regurgitation: clinical implications.

BACKGROUND: Recent studies have emphasized the importance of quantitative assessment of the degree of aortic regurgitation (AR). However, semiquantitative methods have remained mainly used despite their unclear diagnostic value. The aim of this study was to define the sensitivity and specificity of semiquantitative methods compared with the proximal isovelocity surface area method as a reference for the diagnostic of severe AR. METHODS: The degree of AR was evaluated using the proximal isovelocity surface area method and four semiquantitative measurements (left ventricular cardiac output, pressure half-time, diastolic flow reversal, and vena contracta) in 224 patients with a wide range of AR severity. RESULTS: The mean effective regurgitant orifice area was 25 ± 14 mm(2) (range, 3-69 mm(2)), the mean regurgitant volume was 57 ± 31 mL (range, 9-183 mL), and 100 patients (44%) had severe AR (effective regurgitant orifice area ≥ 30 mm(2) or regurgitant volume ≥ 60 mL). Overall, semiquantitative methods had good specificity but poor sensitivity, except the vena contracta, which had good sensitivity and specificity. Sensitivity, specificity, and positive and negative predictive values of the recommended thresholds for severe AR of the four semiquantitative methods were 53%, 89%, 77%, and 73% for left ventricular cardiac output ≥ 10 L/min; 12%, 100%, 100%, and 52% for pressure half-time < 200 msec; 45%, 87%, 79%, and 60% for diastolic flow reversal ≥ 18 cm/sec; and 81%, 83%, 78%, and 85% for vena contracta ≥ 6 mm, respectively. CONCLUSIONS: For the assessment of AR severity, current thresholds appear specific but poorly sensitive, except for vena contracta, which provides good discriminative value. Semiquantitative methods should be integrated into the comprehensive evaluation of AR severity, but severe AR should not be excluded only on the basis of semiquantitative criteria. These results emphasize the need for the quantitative assessment of AR severity.

Size-adjusted left ventricular outflow tract diameter reference values: a safeguard for the evaluation of the severity of aortic stenosis.

OBJECTIVE: We sought to evaluate the relationship among left ventricular outflow tract diameter (LVOTd), gender, and body surface area (BSA) and to evaluate the usefulness of size-adjusted LVOTd reference values in patients with aortic stenosis (AS). AS grading is based on the echocardiographic calculation of the aortic valve area (AVA) and requires LVOTd measurements, one main potential source of error. Transesophageal echocardiography (TEE) is reputed to be more accurate than transthoracic echocardiography (TTE), but validation studies are rare. A safeguard for LVOTd measurements is thus desirable. METHODS: Since January 2006, 3 subsets of patients have been prospectively and concurrently enrolled: 1) TEE group: In 120 patients with and without AS, we prospectively measured LVOTd during both TTE and TEE. 2) Validation set: In 382 patients without aortic valve or ascending aorta diseases, we evaluated the relationship among LVOTd, gender, and BSA. 3) Testing set: In 173 patients with AS, we compared the AVA obtained using measured LVOTd (AVA(MEAS)) and calculated LVOTd derived from a regression determined in the validation set (AVA(CALC)). RESULTS: TTE did not differ from and correlated well with TEE measurements overall (23 +/- 2 mm vs 23 +/- 2 mm, P = .26; r = 0.95, P < .0001) and in patients with AS (N = 43) (24 +/- 2 mm vs 24 +/- 3 mm, P = .15; r = 0.92, P < .0001). LVOTd was linearly correlated to BSA independently of gender (LVOTd = 5.7 * BSA+12.1; r = 0.55, P < .0001). In the testing set, AVA(CALC) did not differ from and correlated well with AVA(MEAS) (1.20 +/- 0.42 cm2 vs 1.23 +/- 0.40 cm2; P = .08; r = 0.89; P < .0001). CONCLUSION: TTE and TEE measurements of the LVOTd provided similar results. LVOTd was significantly associated to BSA and LVOTd, derived from a linear regression linked to BSA independently of gender, provided an acceptable approximation of the AVA. Thus, although accurate measurement of LVOTd is a crucial part of the echocardiographic evaluation of AS severity, the present equation may be used as a safeguard when this measurement is difficult or not possible with TTE.