Predictive criteria for acute heart failure in emergency department patients with acute dyspnoea: the PREDICA study.

OBJECTIVES: The early identification of patients with Acute Heart Failure Syndrome (AHFS) among patients admitted to the Emergency Department (ED) with dyspnoea can facilitate the introduction of appropriate treatments. The objectives are to identify the predictive factors for AHFS diagnosis in patients with acute dyspnoea (primary objective) and the clinical 'gestalt' (secondary objective) in ED. METHODS: PREDICA is an observational, prospective, multicentre study. The enrolment of patients admitted to the ED for nontraumatic acute dyspnoea and data collection on admission were recorded by the patient's emergency physician. The AHFS endpoints were assessed following a duplicate expert evaluation by pairs of cardiologists and emergency physicians. Step-by-step logistic regression was used to retain predictive criteria, and the area under the receiver operating characteristic (ROC) curve of the model was constructed to assess the ability of the selected factors to identify real cases. The probability of AHFS was estimated on a scale from 1 to 10 based on the emergency physician's perception and understanding (gestalt). RESULTS: Among 341 patients consecutively enrolled in three centres, 149 (44%) presented AHFS. Eight predictive factors of AHFS were detected with a performance test showing an area under the model ROC curve of 0.86. Gestalt greater than or equal to five showed sensitivity of 78% and specificity of 90% (AUC 0.91) and diagnosed 88% of AHF in our population. CONCLUSIONS: We identified several independant predictors of final AHFS diagnosis. They should contribute to the development of diagnostic strategies in ED. However, unstructured gestalts seem to perform very well alone.

[Alteration of left ventricular longitudinal systolic function in 2D-strain in primary aldosteronism: A new target organ damage marker]. / Altération de la fonction systolique longitudinale du ventricule gauche en strain bidimensionnel dans l'hyperaldostéronisme primaire : un nouveau marqueur d'atteinte d'organe cible.

OBJECTIVE: Primary hyperaldosteronism is the leading cause of secondary hypertension, and leads to frequent cardiovascular complications. Many studies have studied left ventricular geometry and function in this population, but longitudinal systolic function is still poorly described. METHODS: We studied 35 hypertensive patients with primary aldosteronism, and 35 with essential hypertension matched for age, sex, body mass index, and 24h blood pressure. Patients benefited from an echocardiography to measure the mass and the geometry of the left ventricle, left ventricle ejection fraction, systolic longitudinal, circumferential, and radial strain, and diastolic function. RESULTS: Compared to essential hypertensive patients, patients with primary aldosteronism presented a significantly higher left ventricular mass index and relative wall thickness (60.3±16.1g/m2 vs 47.3±18.6, P=0.003, and 0.44±0.08 vs 0.36±0.06, P=0.00005, respectively), as well as a significantly reduced longitudinal systolic strain (-17.8±3,4 vs -20.3±3,6%, P=0.004). There were no significant differences in the other parameters. CONCLUSIONS: Primary aldosteronism is associated with a deterioration of longitudinal systolic function of the left ventricle compared with essential hypertensive patients. This marker of cardiac damage, reproducible and easily available in routine could help for the screening of these patients.

[Prescription of furosemide in general medicine in Aquitaine: Prospective practice survey among universities general practitioners]. / Prescription de furosémide en médecine générale en Aquitaine. Enquête de pratique auprès des médecins généralistes maîtres de stages universitaires.

OBJECTIVES: Furosemide is essential in the management of patients with congestive heart failure, and provides important iatrogenic complications. We described the prescription of this treatment in general medicine, and tried to identify areas for optimizing its use. PATIENTS AND METHOD: We carried out a prospective inventory of the prescription of furosemide with the general practitioners of the universities of Bordeaux, between May 1, 2017 and July 30, 2017. RESULTS: We obtained data from 119 prescriptions of furosemide. The indications seemed well known, largely dominated by heart failure (67%) and its associated signs (24%). Clinical and biological follow-up (52%) and therapeutic education (42%) seemed relatively infrequent. CONCLUSIONS: Our study confirms the central role of the general practitioner in the prescription of furosemide, the predominant place of heart failure in its indications and the iatrogeny observed. We identified areas of optimization of the safety and effectiveness of the treatment. The reinforcement of training concerning heart failure and its treatments, a better communication between specialties, the implementation of reference systems dedicated to the prescription of furosemide and prescription support software seem promising.

[Screening for familial hypercholesterolemia from low-density lipoprotein cholesterol levels at admission in the coronary care unit]. / Dépistage de l'hypercholestérolémie familiale à partir du LDL cholestérol à l'admission en unité de soins intensifs cardiologiques.

BACKGROUND: Familial hypercholesterolemia (FH) is a frequent genetic disorder that leads to premature atherosclerosis and coronary artery disease. However, knowledge of FH by cardiologists is weak, and FH remains underdiagnosed in France. FH should be suspected when low-density lipoprotein cholesterol (LDLc) levels exceed 1.9g/L (4.9mmol/L) without lipid lowering therapy. PURPOSE: This multicenter retro- and prospective observational study aimed at estimating the prevalence of high LDLc levels in patients admitted in coronary care units, and the impact for the personal and familial follow-up for lipid status. METHODS: Retrospective analysis of all plasma lipid measurements performed at admission in coronary care unit of 4 hospitals in 2017. Retrospective analyses of demographic, clinical, and coronary data of consecutive patients with LDLc levels≥1.9g/L. Prospective 1 year follow-up focused on lipid levels, treatments, and personal and familial screening for FH. RESULTS: Lipid measurement has been performed in 2172 consecutive patients, and 108 (5%) had LDLc level≥1.9g/L (mean age 64±14 years, men 51%). The primary cause of the hospitalisation was acute coronary syndrome (78%), and 22% of patients were free off coronary artery disease. Lipid lowering therapy was present in 9% of patients at admission, and 84% at discharge, with high statins regimen. At 1-year follow-up, control of LDLc level was not performed in 20% of patients, and statin dose was decreased (36%) or withdrawn (7%) in 43%. Lipid measurement has been performed in at least one first degree relative in 37% of patients, and genetic exploration has been done for 3 patients. CONCLUSIONS: Screening of FH in CCU should be routinely performed using the Dutch Score when LDLc is above 1.9g/L. Individual and familial management of patients at high risk for FH screened in CCU should be optimized, both for diagnosis and therapeutic purposes.

[Cardiac resynchronisation therapy in practical terms]. / Resynchronisation ventriculaire et aspects pratiques.

Cardiac resynchronisation therapy, associated with defibrillation therapy or not, has emerged as an effective treatment in heart failure patient. Cardiac resynchronisation technique can be difficult despite improvements in the implantation materials. Knowledge of the anatomy of the coronary venous network, especially the coronary sinus ostium and the distribution of the lateral branches could simplify device implantation. Coronarography with anterograde opacification of the coronary venous system could facilitate pre-selection of appropriate tools for coronary sinus and marginal vein catheterisation.

[Risk factors in a young population with acute myocardial infarction: one year prospective study]. / Facteurs de risque de l'infarctus du myocarde du sujet jeune: registre prospectif sur un an.

OBJECTIVE: The objective of this work is to give epidemiological data, established in a prospective way, on the myocardial infarction in young and its risk factors. METHODS: All patients admitted to the CHG of Pau for myocardial infarction, old, for the men of less than 45 years and for the women of less than 55 years, of November the 1st 2002 to October 31st, 2003, are included. RESULTS: Twenty-seven patients (11.2%) do a myocardial infarction including 44.4% women. The found traditional risk factors are: smoking (92.6%), absence of regular physical activity (81.5%), dyslipidaemia (66.7%), family history of cardiovascular disease (48.2%), hypertension (37.0%), obesity (18.5%), oral contraception (11.1%), diabetes (7.4%), personal thrombotic history (7.4%). The principal emergent risk factors highlighted are: stress (66.7%), inhibitor of the activation of the plasminogene (57.1%), C-reactive protein (50%), lipoprotein a (41.7%), fibrinogen (33.3%), elevated plasma homocysteine (25%), excessive alcohol use (22.2%). None patients does not have an absolute cardiovascular risk > 20%. The clinical characteristics, coronarographic data and the acute treatments were also listed. The prognosis is worse for the women with more risk factors, more complications, and risk of more significant ventricular replanning. CONCLUSION: The principal risk factors of the myocardial infarction in young can be modifiable. The prevention is of primary importance. The therapeutic education of the patients corresponds to the total assumption of responsibility required by this pathology.

Treatment of drug-eluting stents in-stent restenosis with paclitaxel-coated balloon angioplasty: Insights from the French "real-world" prospective GARO Registry.

BACKGROUND: Data about paclitaxel-eluting balloon (PCB) angioplasty to treat drug-eluting stents (DES) in-stent restenosis (ISR) were mainly collected in selected patient populations in the setting of randomized trials. The main goal of this prospective registry was to confirm the positive findings of these studies in an unselected population in clinical practice. METHODS: Consecutive patients with DES-ISR treated by PCB angioplasty were recruited in this prospective real-world registry. The primary endpoint was clinically driven target-lesion revascularization (TLR) at 9 months. Secondary endpoints included acute technical success, in-hospital outcomes, 9-month major adverse cardiac events (MACE) a composite of death, myocardial infarction (MI) and TLR and the occurrence of target vessel revascularization. RESULTS: A total of 206 patients (67.7 ± 10.2 years, 80.6% male, 41.3% diabetics) with 210 lesions were recruited. Unstable coronary artery disease was present in 55.3% of patients. The time from DES implantation to DES-ISR was 3.0 ± 2.4 years. Quantitative analyses revealed that patterns of treated DES-ISR were focal in 55.7% and diffuse in 44.3%. The reference diameter was 2.76 ± 0.64 mm. The 9-month follow-up rate was 90.8% (187/206). At 9 months, the TLR rate was 7.0% (13/187) whereas the rates for MACE, MI and cardiac death were 10.7% (20/187), 4.8% (9/187) and 2.1% (4/187) respectively. Results were consistent in patients with paclitaxel and non-paclitaxel-eluting stents (PES) ISR. CONCLUSION: This large prospective registry demonstrated acceptable rates of TLR and MACE at 9 months after treatment of DES-ISR by PCB angioplasty. PCB angioplasty was equally effective in patients with PES-ISR and non PES-ISR.

[Prehospital management of acute myocardial infarction. Data from a consecutive cohort of 115 patients in a French region in 2002]. / Prise en charge préhospitalière de l'infarctus du myocarde à la phase aiguë dans la région sanitaire VI. Evaluation prospective sur l' année 2002.

The treatment of acute myocardial infarction is in evolution. Several strategies are utilized ranging from thrombolysis to percutaneous angioplasty (PCI), and the combination of both treatments; the latter providing an interesting compromise between treatment delay and efficiency of early myocardial reperfusion. We reviewed the early treatment strategies of acute myocardial infarctions undertaken by Samu in region 6 (south west of France) in 2002. Of a cohort of 115 patients, 83 patients (72.1%) had a revascularisation strategy: 56 (48.7%) had a primary PCI, and 27 (23.4%) had thrombolysis (92.6% being performed in the prehospital treatment). In those undergoing thrombolysis, 13 patients (48%) had ongoing features of ischaemia; excluding 4 patients who died during transport, all had a PCI at the admission in hospital. For the 14 patients with successful thrombolysis, 5 had facilitated PCI at the admission, 8 had a delayed angioplasty and 1 patient did not have angiography. Although the number of patients receiving thrombolysis in this study was small, this treatment was begun 62 minutes before primary PCI. There are important intra and extra hospital delays to the commencement of PCI. The easy utility of thrombolysis together with the potential to PCI argue in favour for a strategy of prehospital thrombolysis associated with a facilitated angioplasty.

Clinical characteristics affecting success or failure of PTCA in patients with multiple vessel disease and poor candidates for surgery.

A special form of complex coronary angioplasty is represented by the extension of indications for percutaneous transluminal coronary angioplasty (PTCA) to patients with multivessel disease (MVD) for whom surgery is not indicated, and thus for whom surgical standby is not available. Over a two-year period, 254 consecutive coronary patients with multivessel disease underwent PTCA under such conditions. These patients could not benefit from surgery for various reasons. Of the 612 arteries involved, 155 were occluded, 47 had been previously bypassed. A distal nonbypassable lesion in one of the three major arteries was found in 244 patients, 61 had suffered from a previous infarct, 24 demonstrated an ejection fraction below 0.40, and in 19 a single patent vessel was found. Fifteen patients were in cardiogenic shock and 69 procedures were undertaken for unstable angina. Of this latter group, 25 emergency PTCA were attempted for refractory unstable angina, and 44 additional emergency procedures were directed to the treatment of acute infarct. A total of 40 intra-aortic counterpulsations were needed. As far as possible the procedure aimed at full revascularization. Immediate outcome is strongly affected by the clinical context, and despite a rather constant initial success rate (88-95%), the procedural mortality (directly related or not) can change dramatically with clinical factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term beneficial effects of PTCA on segmental early relaxation in disease of the left anterior descending coronary artery.

The relationship between regional left ventricular (LV) motion and global pressure relaxation of the left ventricle remains unclear. To clarify the recent concept of segmental early relaxation in coronary artery disease, the authors investigated two groups of patients. In group I, all 12 patients (mean age 47 +/- 7 years) exhibited evidence of a normal heart after an extensive investigation. In group II, 25 patients (55 +/- 7 years) presented an isolated stenosis of the left anterior descending coronary artery, and they underwent a hemodynamic investigation before and after (six to nine months) a durable successful percutaneous transluminal coronary angioplasty (PTCA). After all conventional hemodynamic measurements had been done, a quantitative frame-by-frame analysis of left ventricular wall motion was conducted. The authors' method is derived from that of Ingels, applying to LV cineangiograms filmed in 30 degrees right anterior oblique view at a 50 frames/second rate. Thus segmental wall motion is analyzed in terms of amplitudes (%), velocities of shortening and lengthening in circumferences/second (circ/sec), and times of events (%). Statistical results took into account the reproducibility of the method. Main results regarding the control state of group II consisted of an asynergic motion of the anterior region taking place from end systole to early diastole: 1. Early end of contraction in anterior segments (% of systolic time interval: 88 +/- 14% vs 96 +/- 6% in group I, p less than 0.001) 2. Asynchronism at end systole (maximal velocity of shortening - 0.4 +/- 2.3 circ/sec in anterior segments vs 0.05 +/- 1.9 in inferior segments, p less than 0.02) 3. An early but poor outward anterior wall motion (anterior lengthening at 0.04 sec after the end of ejection 2.9 +/- 10% in group II versus 5.4 +/- 7.2% in group I, p less than 0.05) These abnormalities are strongly correlated with a significant impairment of peak negative diastolic pressure/diastolic time (dP/dt) (1500 +/- 400 mmHg. sec-1 vs 1850 +/- 410 in group I, p less than 0.02). Long-term beneficial effects of PTCA in group II were characterized by an almost complete normalization, both asynergy and relaxation taking place back within the normal range. The authors conclude that in this kind of patient, peak negative dP/dt could be an index of an asynergic segmental motion, this one being correctly analyzed and quantified on LV cineangiograms with our method.

[Multiple left coronary-ventricular microfistula and apical hypertrophy]. / Microfistules multiples coronaro-ventriculaires gauches et hypertrophie apicale.

Coronary arterio-systemic fistula is a rare condition, especially when multiple fistulae communicate with the left ventricule. The association of multiple congenital coronary artery-left ventricular fistulae and apical hypertrophy has not been previously reported. The authors report three cases, all in women, with multiple coronary artery-left ventricular fistulae and apical hypertrophy diagnosed by angiography. The association may not be coincidental as multiple microfistulae could cause abnormalities of the microcirculation and result in reactional myocardial hypertrophy.

[Myocardial infarction caused by the thrombosis of the common trunk of the left coronary artery. Fatal outcome despite an early obstruction removal by angioplasty. Apropos of a case]. / Infarctus du myocarde par thrombose du tronc commun de la coronaire gauche. Evolution fatale malgré une désobstruction précoce par angioplastie. A propos d'un cas.

We report an exceptional case of acute myocardial infarction due to thrombosis of the left main coronary artery in a 39-year old male patient. After failure of recanalization by systemic fibrinolysis, percutaneous angioplasty under circulatory assistance was successfully performed pending a possible transplantation. The patient unfortunately died of haemodynamic disturbances 48 hours after the infarction.

[Refractory unstable angina. Emergency treatment by coronary artery angioplasty under aortic counterpulsion]. / Angor instable rebelle. Traitement d'urgence par angioplastie coronaire sous contrepulsion aortique.

We report our experience of 15 transluminal coronary angioplasties performed in an emergency in 13 patients (mean age 67 +/- 8 years) with refractory unstable angina. The procedures were conducted under diastolic counterpulsation effected by means of an intra-aortic balloon. The angina was of the threatening infarction type on 11 occasions and of the threatening extended infarction on 4 occasions. Electrocardiographic abnormalities were recorded in the anterior (11 cases) or in the inferior (4 cases) territory. Three patients had a very alarming haemodynamic status, with acute pulmonary oedema in two and cardiogenic shock in one. After intra-aortic counterpulsation was installed and the clinical signs were stabilized, coronaro-ventriculography was performed, leading to a decision of immediate angioplasty since age, underlying diseases, myocardial function and diffused lesions made most of the patients unsuitable for surgery. In multiple vessel patients electric and angiographic data were used to locate the tight stenosis (92% in all cases) responsible for the acute coronary ischaemia. The stenosis was found to affect the anterior interventricular artery in 9 cases, the circumflex artery in 2 cases, the right coronary artery in 2 cases and a saphenous shunt on the anterior interventricular artery in 2 cases. Immediate arteriographic and clinical success was obtained in 12 out of 15 cases (80%); there were 3 failures with 2 transmural infarctions. Later on, 2 patients underwent aorto-coronary bypass and 1 died of myocardial failure and pulmonary superinfection 3 weeks after the procedure. Ten of our 13 patients were stabilized and were discharged under medical treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

[Echocardiographic diagnosis of aortic dissection: contribution of pulsed Doppler. Apropos of 29 cases]. / Diagnostic échocardiographique des dissections aortiques: apport du Doppler pulsé. A propos de 29 cas.

Echocardiography is universally recognized as a first-line examination easy to perform at all times in patients with thoracic pain suggestive of aortic dissection. But like all diagnostic methods, it has its limitations and pitfalls. The present study, based on 29 consecutive cases, demonstrates the value of pulsed Doppler echocardiography in the diagnosis and monitoring of aortic dissection. When the echocardiographic images are typical of the disease, the Doppler technique helps evaluate the lesions (aortic insufficiency, number of patent channels), but it is mainly in cases with doubtful echocardiographic findings that the Doppler technique provides elements that clinch the diagnosis, notably by showing the presence ot two patent channels with different blood flows. In addition, we would like to draw attention to a new and useful sign: flapping ot the dissected intima when the Doppler window is over it; we observed this sign in 24 of our 29 patients.

[Double aneurysm occurring on a venous aortocoronary graft]. / Double anévrysme sur greffon veineux aorto-coronaire.

The authors report the case of a 48-year old patient admitted to hospital for unstable angina 13 years after primary myocardial revascularisation by a saphenous vein aorto-coronary bypass graft. Routine chest X-ray showed a left para-hilar opacity which CT scan and angiography confirmed to be aneurysmal and pseudoaneurysmal dilatations of the saphenous vein bypass graft.

[Value of eptifibatide during salvage angioplasty with coronary stenting after failure of thrombolysis. Report of a series of 41 patients]. / Intérêt de l'eptifibatide au cours de l'angioplastie de sauvetage avec stenting coronaire après échec de thrombolyse. A propos d'une série de 41 patients.

AIM: To evaluate the risks and the significance of the use of an anti-GPIIb/IIIa, in this case Eptifibatide, during angioplasty following presumed failure of thrombolysis in the acute phase of myocardial infarction. METHOD: Patients thrombolyzed following MI < 6 hours. Presumed failure of reperfusion with full dose thrombolysis. Analysis evaluated the success of angioplasty associated with anti-GPIIb/IIIa treatment and the hospital phase outcome. RESULTS: 41 consecutive patients, 32 male (78%) and 9 female (22%), were included. Infarction concerned the anterior region in 22 cases (54%) and inferior in 19 cases (46%). Fibrinolysis was performed using Alteplase in 28 patients (68%) and Reteplase in 13 patients (32%). Radial access was performed in 32 cases (78%). All of the patients received Eptifibatide with a bolus then infusion from their admission to the haemodynamic suite, on average 1 h 30 after the start of thrombolytic treatment. A total of 49 stents were implanted in 41 patients. A flux of TIMI 3 was obtained in 37 patients (90.2%). TIMI 2 in 2 patients (4.9%) and no reflow in 2 patients (4.9%). Four counter-pulsions by intra-aortic balloon were necessary (9.8%) for cardiogenic shock. No decrease in TIMI flux was observed after the angioplasty procedure. The main complications were a death from cardiogenic shock in one patients (2.4%), a non-fatal digestive tract haemorrhage in 2 cases (4.9%) and a single femoral haematoma requiring transfusion. CONCLUSION: The initial results were encouraging: high success rates, rare vascular complications, a probable consequence of the radial approach. The association of an anti-GPIIb/IIIa, Eptifibatide, therefore appears achievable during angioplasty with the positioning of a coronary endoprosthesis following the presumed failure of full dose thrombolysis.

[Takayasu disease revealed by dorsalgia]. / Dorsalgies révélant une maladie de Takayasu.

UNLABELLED: Takayasu arteritis is an uncommon inflammatory arteritis especially in children. We report a case. CASE REPORT: A 11-year-old boy presented dorsalgia with inflammatory syndrome. One year later, the investigation of an hypertension with asymmetric blood pressure revealed an aortic coarctation and a bilateral renal arteries stenosis leading to Takayasu's arteritis diagnosis. CONCLUSION: Takayasu's arteritis must be evokated in young children in case of associated hypertension and inflammatory syndrome.

Clinical factors affecting the immediate outcome of PTCA in patients with unstable angina and poor candidates for surgery.

Percutaneous Transluminal Coronary Angioplasty (PTCA) has been successfully applied in unstable angina to carefully selected patients. In this study, PTCA was performed in 277 consecutive patients suffering from unstable angina and for whom bypass surgery was not a valid alternative because either of inoperable conditions or of emergency, or because surgery was not the best option. All patients were admitted first to the intensive care unit where an attempt was made to control unstable angina under conventional medical therapy using at least iv nitroderivative, heparin, and calcium blockers. After a standardized preparation PTCA was performed either as an emergency procedure in medically refractory unstable angina (107 cases) or as an elective procedure in controlled situations after a 7 to 10 days symptom-free period. Three hundred fifty-three coronary vessels were attempted. Results of this group are compared with those of a control group made of 670 consecutive stable patients recruited during the same period, and clinical characteristics are envisaged as potential predictive factors. Unstable angina is undoubtedly associated with a higher overall complication rate, but the immediate outcome is strongly affected by the clinical context. As an example, respective success and mortality rates are: 93% and 0% when a full revascularization is attempted; 91% and 0% in elective procedures in patients under 60; 87% and 1.2% in elective PTCA for multiple vessel disease; 80% and 6.5% in emergency PTCA; 80% and 11% in the overall triple vessel disease; 84% and 16% in patients with deeply altered ejection fraction; and 58% and 26% in triple vessel disease with 2 previously occluded coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

PTCA with side-by-side balloon using fixed guide wire systems: a potential alternative autoperfusion device--an in vitro study.

The use of "hugging balloons" for the implementation of a coronary angioplasty is a well-known and much-written-about technique. It has not, on the other hand, ever been stressed that two inflated hugging balloons are not totally obstructive, leaving enough space, between the balloons and the arterial wall, for perfusion. The cross section of this free area can be as much as 12% of the total arterial cross section, when the side-by-side balloons are of a relatively similar size. Calculations show that similar total conduit cross sections are achieved when inflating either a 3.0 balloon or two 2.0 side-by-side balloons. An in vitro experiment compares how systems using 2.0 double balloons and a 3.0 autoperfusion balloon affect the distal flow of a 3 mm internal diameter conduit. A semi-rigid silastic tubing is perfused with a 5% glucose isotonic solution at various predetermined proximal pressure levels. Distal pressures and flows are measured at different stages: with no balloon, with deflated balloons, and with inflated balloons. Comparison shows that 1) the double balloon system offers little resistance to flow compared to the autoperfusion balloon; 2) this system's rate of perfusion run-off is hardly affected and is constantly better than with the autoperfusion balloon; 3) this difference is all the more marked, the lower the proximal perfusion. These results suggest that the use of a double balloon could, in some cases, provide an alternative solution to autoperfusion equipment. Further clinical studies are needed to test this hypothesis.