[Arrhythmogenic right ventricle: dysplasia or cardiomyopathy? Value of left ventricle ejection fraction]

The left ventricular ejection fraction (LVEF) of 76 patients suffering from arrhythmogenic dysplasia or cardiomyopathy of the right ventricle (ventricular tachycardia associated with structural abnormalities of the right ventricle) demonstrated two subgroups situated above and below 45%. Values of LVEF less than 45% were similar to those of a control population of 6 cases of idiopathic dilated cardiomyopathy with ventricular tachycardia of left ventricular origin (p = 0.2). These patients also have the same unfavourable long-term prognosis. Histological data obtained from four cases belonging to the group of patients with dysplasia or cardiomyopathy of the right ventricle with a low ejection fraction demonstrated the presence of signs of myocarditis involving both ventricles. This suggests that these patients may suffer from an infectious phenomenon superimposed on a specific histological substrate, which may lead to deterioration of their myocardial function. These results are in line with those of the literature. The term arrhythmogenic cardiomyopathy of the right ventricle should therefore be reserved to the subgroup of patients with an LVEF less than 45%. Finally, arrhythmogenic cardiomyopathy of the right ventricle appears to be a complication of dysplasia following the development of a myocarditic phenomenon. This may explain the wide range of clinical forms observed in patients with ventricular tachycardia of right ventricular origin associated with structural abnormalities of the right ventricle.

[Outcome of arrhythmogenic right ventricular dysplasia. Apropos of 4 cases]

The authors propose a classification of the outcome of arrhythmogenic right ventricular dysplasia with reference to 4 selected cases with a follow-up period of over 9 years. In type I, the left ventricular ejection fraction is normal (EF > 50%) and the risk, exclusively arrhythmic, can be controlled by appropriate antiarrhythmic therapy. This is the commonest form of arrhythmogenic right ventricular dysplasia with different varieties according to the degree of dilatation of the right ventricle. In type II, there is a variable degree of left ventricular involvement (30 < EF < 50%) either by extension of a comparable disease process as observed in the right ventricle or by an isolated or superimposed phenomenon of myocarditis. This form is stable and may remain stable for many years providing the arrhythmias are correctly treated. In type III, progressive degradation of the myocardium is observed over a period of about 10 years with a clinical presentation comparable to that of certain arrhythmogenic dilated cardiomyopathies which are often hereditary. In this case, the patients have an arrhythmic risk associated with that of cardiac failure which becomes progressively irreversible. The histology shows interstitial fibrosis with biventricular lymphocytic infiltration suggesting an autoimmune phenomenon. Therefore, the classification of cases of arrhythmogenic right ventricular dysplasia depends on the potential evolutivity of the lesions. When the patient is seen in the early stages of the disease, the prognosis should be garded, especially in a hereditary form.

[Fulguration of extrasystolic ventricular focus]

A case is presented of symptomatic premature ventricular contractions refractory to drug therapy with right bundle branch block QRS morphology and left axis deviation in a 68-year-old female without structural heart disease. Endocardial mapping localized the extrasystolic focus at meso-inferoapical region of the left ventricular septum suggesting an origin from the Purkinje network of the left posterior fascicle. Catheter ablation with direct-current energy abolished extrasystolic complexes, without complications. The patient remained asymptomatic over a follow-up of 3 months.

Time- and frequency-domain analyses of the signal-averaged ECG in patients with arrhythmogenic right ventricular dysplasia

BACKGROUND

Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by recurrent ventricular tachycardia of right ventricular origin and a cardiomyopathy with hypokinetic areas involving the free wall of the right ventricle. Subjects have a risk of sudden cardiac death, particularly during sports and strenuous exercise. Routine clinical examinations may be normal, but fragmented or delayed electrograms are usually recorded in the right ventricle of these patients. However, the frequency with which late potentials are detected by conventional time-domain analysis of the signal-averaged ECG (SAECG) is not high. This study evaluated the usefulness of the frequency-domain analysis of the SAECG in addition to the conventional time-domain analysis for a screening test to detect patients with ARVD.

METHODS AND RESULTS

SAECG was recorded by using a bipolar X, Y, and Z lead system in 28 patients with ARVD (mean age, 38 +/- 13 years) and 35 age-matched normal subjects (mean age, 35 +/- 11 years). The conventional time-domain analysis of the SAECG was performed at two different high-pass filter settings, 25 and 40 Hz, and the low-pass cutoff frequency was fixed at 250 Hz. The fast-Fourier transform analysis of SAECG was performed using a Blackman-Harris window. Area ratio 1 (area of 20 to 50 Hz)/(area of 0 to 20 Hz) and area ratio 2 (area of 40 to 100 Hz)/(area of 0 to 40 Hz) were calculated. In the conventional time-domain analysis, 20 (71%) and 18 (64%) patients had positive criteria at filter settings of 25 and 40 Hz, respectively. In the frequency-domain analysis, 18 (64%) and 20 (71%) patients had abnormal values in area ratios 1 and 2, respectively. Combining the time- and frequency-domain analyses, all patients were judged positive, with a sensitivity of 100% and a specificity of 94%.

CONCLUSIONS

Each result of the time- and frequency-domain analyses revealed that both methods had equivalent value. Combining the two domain analyses improved the sensitivity without reducing the specificity. These findings suggest that combining the time- and frequency-domain analyses of the SAECG may be useful as a screening test to detect patients with ARVD.

[Fulguration and radiofrequency in ventricular tachycardia]

Eighty-nine cases of ventricular tachycardia, resistant to antiarrhythmic therapy, were treated over a 10 year period by high energy D ablation (fulguration). This series included 37 cases of myocardial infarction with a mean ejection fraction of 30%. The mean follow-up period of the survivors was 61 months and clinical efficacy was 87.9%. Twenty-three cases of arrhythmogenic right ventricular dysplasia, aged 40 years, and with an ejection fraction of 57%, followed up for 71 months, had a clinical efficacy of 83%. Twelve patients had verapamil sensitive (fascicular) ventricular tachycardia. Their age was 30, their ejection fraction 65%, the follow-up period 55 months, and the clinical efficacy was 100%. Ten patients had primary dilated cardiomyopathy. Their age was 35, their ejection fraction 23%, the follow-up period of 38 months with a clinical efficacy of 80%. Four patients, aged 21, had operated congenital heart disease with an ejection fraction of 60%, a follow-up of 36 months and a clinical efficacy of 100%. Finally, 3 patients had idiopathic infundibular ventricular tachycardia. Their age was 36, the ejection fraction 62%, the follow-up period was 72 months and the clinical efficacy was 67%. Non lethal complications were observed in 16% of cases, mainly haemopericardium requiring pericardocentesis in 4.5% of cases. The operative mortality and in the month following ablation was 9.2%, observed mainly during the learning period. These results show that fulguration is not without risk, but in skilled hands, it gives remarkable results in the majority of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

[Radiofrequency ablation in ventricular tachycardia: initial experience and evaluation of its limitations]

The purpose of this paper is to report our initial experience with radiofrequency catheter ablation in 21 patients with ventricular tachycardia of different etiologies and to evaluate the causes which play a role in its limitation. The results show a low rate of effectiveness: total clinical success of 43%. Nevertheless there was a high success rate in a specific subsets of patients. The results depends on several factors: the electrophysiologic mechanisms and substrates of the tachycardia, the criteria to localize the critical area perpetuating the arrhythmia and the biophysical aspects of radiofrequency energy. Its usefulness is manifested in ventricular tachycardia with structurally normal heart and it has a limited success in cases with organic heart disease. Improvement of technical aspects and better understanding of the mechanisms of the tachycardia and characteristics of the target site will enhance the results of radiofrequency catheter ablation in ventricular tachycardia.

[Transcatheter ablation of atrioventricular accessory pathways. Immediate results and long-term follow-up]

We present the immediate results and follow-up, from our initial serie of patients, where radiofrequency was attempted to ablate atrio-ventricular accessory pathways. Initiation policy included direct current-shocks following every unsuccessful radiofrequency session. Initial ablation success rate with radiofrequency solely was 75% (17/22), same as when direct current-shocks were associated 80% (8/10); but accessory pathway conduction recurrence was present only in this latter (6/10). During follow-up period of 18 to 25 months, from the recurrence group, one patient had spontaneous delta-wave disappearance, and four more required two to three ablation sessions. Permanent elimination with both methods was attained in 91% (20/22 pathways), and all patients remain asymptomatic, and drug free. There were one acute major complication, but no deaths. Because of its superior initial success rate, minor technical requirements, and their economical implications, radiofrequency catheter ablation of accessory pathways is the first choice of treatment. At our institution, direct current-shock remain an alternative method whenever a serious tachycardia prevents radiofrequency treatment.

[Ablative methods, therapeutic alternative to medical treatment for junctional tachycardia]

The clinical syndrome corresponding to junctional tachycardia is generally known as Bouveret's disease, but actually corresponds to two quite separate entities: 1) tachycardia related to a secondary atrioventricular pathway or Kent bundle; 2) intranodal tachycardia arising in the atrio-ventricular node. Until recently, anti-arrhythmics were used to treat most of the cases of accessory pathways. If this was unsuccessful or if the anti-arrhythmics induced adverse effects and in life-threatening cases affecting Kent bundles, surgical section was sometimes proposed, carrying a non-negligible risk of morbidity and mortality. Intranodal arrhythmia is not a serious, but may call for prophylactic antiarrhythmic treatment if it becomes too frequent and disabling. Before the advent of ablative treatment, there was no satisfactory alternative to antiarrhythmic treatment. Ablation of the accessory pathways or selection ablation of the slow pathway of the atrio-ventricular node (sometimes of the rapid pathway) is not achieved by applying a high-frequency current (radiofrequency), which has virtually replaced fulguration (destruction using a modified electrical current). In both types of tachycardia, a cure is obtained in 90% of cases with a low incidence of complications and virtually no risk of mortality, which contrasts favorably with long-term antiarrhythmic treatment (or surgical section of Kent bundles), which justifies the large-scale development of radiofrequency ablation.

[Repolarization and intraventricular conduction disorders in arrhythmogenic right ventricular dysplasia]

Right ventricular dysplasia may lead to sudden cardiac death an adolescent or adult with little or no symptoms. Identification of this condition in the high-risk population appears to be an objective to be attained in the near future. Thorough ECG analysis seems to be a non-invasive and inexpensive technique which could be used as a first approach for screening of the disorder. In a series of 50 cases of arrhythmogenic right ventricular dysplasia compared with a control group, the diagnosis of ARVD could be determined by ECG with 84% sensitivity and 100% specificity if QRS duration in leads V1, V2 or V3 was longer than 110 ms, T wave was negative in V2 or if T wave was negative in V1, but in this latter case only provided incomplete right bundle branch block was present.

[Treatment of ventricular tachycardia by endocardial fulguration. Apropos of 86 cases]

Between 1983 and 1991, 86 cases of ventricular tachycardia (VT) resistant to antiarrhythmic therapy were treated by endocardious catheter fulguration: there were 21 cases of right ventricular dysplasia (RVD), 35 chronic myocardial infarctions (MI), 11 dilated cardiomyopathies (DCM), 10 bundle branch VT, 5 idiopathic septal VT, 3 operated Fallot procedures, 1 Ebstein's anomaly. There were 69 men and 17 women aged 14 to 76 years (average 45 +/- 18 years). The ejection fraction was under 30% in 37 cases. Forty-five VTs were permanent or recurred several times daily; 6 were inducible despite drug therapy and 35 patients had monthly recurrences. A total of 141 different forms of VT were treated in 133 procedures. One session was sufficient in 49 cases; 2 sessions were required in 29 cases; 3 sessions in 6 cases and 4 sessions in 2 cases. A total of 480 DC shocks were delivered with energies of 160 to 300 joules. The CPK-MB levels were 37 +/- 30 i.u./l. The following complications were observed: 7 perioperative deaths, 2 cardiac tamponades requiring surgical drainage, 1 permanent AV block, 5 reversible left ventricular failures. Follow up concerned 79 patients: 5 were followed up for less than 3 months with death occurring from cardiac failure which had been present before the ablation procedure without recurrence of VT. Seventy-four patients were followed up from 3 to 111 months (56 +/- 33 months). Thirty-two patients were without any antiarrhythmic therapy and had no recurrence of VT. Two of these patients developed a different form of VT 2 and 6 years after the catheter ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Sustained monomorphic ventricular tachycardia in non ischemic heart diseases]

Sustained ventricular tachycardia in the absence of coronary artery disease is mainly observed in diffuse left ventricular cardiomyopathy especially dilated but sometimes hypertrophic, and in right sided cardiomyopathies such as ventricular dysplasia, more difficult to diagnose. More rarely, other localised abnormalities, mitral valve prolapse, cardiac tumour and idiopathic aneurysm, may give rise to this arrhythmia. Irrespective of the case, sustained ventricular tachycardia carries a poor prognosis during the most advanced stages of a myocardial disease. The therapeutic strategy remains the same as that of other cases of sustained ventricular tachycardia, drug therapy generally orientated by the results of programmed ventricular stimulation with the exception of Class I antiarrhythmics when the ejection fraction is under 30%, and non-pharmacological methods when drug therapy fails.

[Arrhythmogenic right ventricular dysplasia. A new clinical entity]

Arrhythmogenic right ventricular dysplasia has been identified in 1977. It affects the right ventricle and its etiology is unknown. It has been recently included in the group of cardiomyopathies since it affects mainly the right ventricular muscle. It is found in young adults, frequently sportsmen who have a nearly normal cardiac physical examination. Ventricular arrhythmias could lead to palpitations, syncopes or even sudden death. This accident could be the first presenting sign of the disease. Two physiopathogenic mechanisms have been considered: heredo-familial origin or the result of a burned out myocarditis which could be the result of an abnormal immunological response. Its treatment mainly involves antiarrhythmic drugs. In the resistant cases ablative techniques, implantable defibrillator or surgery and even cardiac transplantation could be considered. Correctly treated, ARVD has a good prognosis. More extensive studies are necessary both on the clinical as well as the basic science standpoints.

[Holter and sudden death: value in a case of arrhythmogenic right ventricular dysplasia]

The authors report the first case of arrhythmogenic right ventricular dysplasia presenting with a sudden death due to primary ventricular fibrillation (ventricular fibrillation not preceded by ventricular tachycardia) recorded by the Holter method. The patient was a 56 year old man whose only complaint was near syncopal case is the fact that it is the first documented case of ventricular fibrillation revealing arrhythmogenic right ventricular dysplasia, the diagnosis of which was made at autopsy. In addition, the Holter recording showed the factors which triggered the arrhythmia: the "trigger" of 4 monomorphic ventricular extrasystoles during the minute preceding the ventricular fibrillation; the arrhythmogenic substrate giving rise to late ventricular potentials and, finally, the analysis of the R-R intervals suggesting a role of the sympathetic and parasympathetic nervous systems. Holter recordings could help identify subjects at high risk of severe ventricular arrhythmias.

[The radiofrequency and the elimination of accessory atrioventricular pathways. The factors related to successful transcatheter ablation]

Some factors related with successful radiofrequency catheter ablation were retrospectively analyzed from the initial patients with WPW syndrome that underwent this therapy. They were 21 patients, and success rate with radiofrequency therapy was 73%. Conventional conduction intervals were obtained from catheter ablation electrograms. Only ventricular activation around Delta-wave onset, and earliest retrograde atrial activation were statistically significant for successful ablation (P < 0.05 both). Inadvertent interruption of AV-His bundle was produced ablating a septal accessory pathway, and no mortality procedure-related was observed. We conclude that radiofrequency catheter ablation of accessory pathways represents nowadays, an effective solution in patients with symptomatic arrhythmias, besides its high success rate and low risks, but different mapping criteria should be considered to attain an efficient elimination of atrioventricular accessory-pathways.

[Ventricular anti-arrhythmic treatments during postinfarction]

Antiarrhythmic agents may be prescribed in the post-infarction period either as systematic therapy to prevent sudden death or as prophylactic treatment against recurrences of documented life-threatening arrhythmias. Systematic therapy or even the treatment of symptomatic ventricular extrasystoles by Class IC anti-arrhythmics is associated with an increased risk, especially in patients with a low risk of sudden death at the outset. Betablockers are effective on symptoms: they are not always effective on the arrhythmia but at least they do not aggravate the mortality of these patients. However, for high risk patients with post-infarction left ventricular dysfunction, betablockers are the only drugs which have a proven efficacy: they should therefore be prescribed, especially those whose efficacy has been demonstrated, at the same dosages as those used in clinical trials. Preventive treatment of sustained ventricular tachycardia should be chosen with respect to the patient's hemodynamic status. When the ejection fraction is under 40%, amiodarone and betablockers are the drugs of first intention, with controls of their efficacy by the inability to induce or the slowing of the tachycardia rhythm during endocavitary electrophysiological studies.

Factors predicting success in DC catheter ablation of accessory pathways

In a series of 33 patients with accessory pathways, 26 had successful catheter ablation (fulguration [23 patients] or modification [3 patients]) of their accessory pathway conduction, and could be considered as a clinical success. One hundred thirteen single discharge or double discharge shocks were delivered, and each shock was studied to reveal which parameters were important to predict the success or failure of catheter ablation. Double discharge shocks resulted in successful accessory pathway modification or ablation twice as often as single discharge shocks (32% vs 16%). This effect was more pronounced in left lateral accessory pathways (48% vs 4%). Shocks in the electrophysiologically defined ventricular zone were more likely to be successful (33%) than shocks delivered in the atrial zone (14%), irrespective of accessory pathway location. The presence of a probable Kent potential was the parameter most strongly associated with success. The parameter most strongly associated with failure, with a 100% negative predictive value, was the absence of earliest activation recorded on the ablating catheter prior to shock delivery. An AV interval of < 60 msec significantly divided the successful from the unsuccessful shocks (P = 0.01). The VA interval during orthodromic reciprocating tachycardia or right ventricular stimulation did not allow for significant division into successful and unsuccessful attempts in this relatively short series. VA intervals, when longer, were predictive of failure but, when shorter, had low positive predictive value. Mean follow-up in 25 successful patients was 15 +/- 6 months. All patients did well in the follow-up period. Neither those patients with ablation nor modification of the accessory pathway had recurrent episodes of tachycardia or required pharmacological treatment for control of arrhythmias.

[Ventricular tachycardia in a patient with rate-responsive cardiac pacemaker]

The authors report a case of syncopal ventricular tachycardia in a patient with a respiratory-dependent rate responsive pacemaker, followed-up for valvular heart disease with severe left ventricular dysfunction and sustained atrial and ventricular arrhythmias. The introduction of low dose betablocker therapy with reinforcement of the treatment of cardiac failure controlled the ventricular arrhythmia, after suppression of the data responsive function had been shown to be ineffective. The authors discuss the role of the rate responsive function in the triggering of the ventricular tachycardias.

[Right ventricular dysplasia]

Arrhythmogenic right ventricular dysplasia is responsible for ventricular tachycardia affecting an apparently healthy heart. It can sometimes lead to sudden death, which may be the presenting symptomatology of the disease. It results from fibro-adipose infiltration of the free wall of the right ventricle, and sometimes of the septum, possibly secondary to myocarditis. The prognosis depends upon the quality of the left ventricle. If it is healthy, the only risk is that of arrhythmia. Treatment using anti-arrhythmic drugs is most often effective and, with proper management, the prognosis is good and the risk of sudden death eliminated. If the left ventricle is abnormal, there is the risk that dysplasia associated with arrhythmia will progress to right then congestive cardiac failure in the context of a dilated idiopathic cardiomyopathy with ventricular tachycardias originating on the right side. Arrhythmogenic right ventricular dysplasia is a notable cause of sudden death in athletes. Routine screening of such individuals is justified, as is that of those with high risk occupations (locomotive and vehicle drivers, etc.).

Electrophysiological effects of intravenous rilmenidine in man

Ten patients (44 y), 6 with the Wolff-Parkinson-White syndrome, and none with hypertensive disease, underwent electrophysiological studies before and after intravenous infusion of a single dose of 1 mg rilmenidine administered over 15 min. The regimen produced a mean plasma rilmenidine concentration of 3.16 ng.ml-1 at the end of the infusion. There was no significant change in sinus cycle length, PR interval, QRS, QT duration or in PA, AH and HV intervals. Estimated sinoatrial conduction time and corrected sinus node recovery time did not significantly change. In one patient, however, an abnormal pause was noted after termination of rapid atrial pacing. The right atrial effective refractory period decreased from 209 to 194 ms. There was no significant change in the anterograde and retrograde block cycle length or in the refractoriness of the nodal, ventricular and accessory pathways. The cycle length of induced reciprocating tachycardia decreased slightly from 374 to 351 ms. No patient exhibited an abnormal response to the carotid sinus massage. The findings indicate that intravenous administration of 1 mg rilmenidine exerts modest effects on the electrophysiological parameters of the human heart.

[The role of Holter monitoring and electrophysiological studies in the evaluation of ventricular anti-arrhythmia agents]

The roles of Holter monitoring and electrophysiological studies (EPS) in the evaluation of antiarrhythmic drugs for ventricular arrhythmias are to record their effects on ventricular extrasystoles (VES) and ventricular tachycardia (VT), and to search for undesirable rhythmological effects. The usual protocol is to perform baseline studies and then repeat them after a certain period of treatment using a number of modalities, comparison with placebo, control group, in acute or oral administration. Holter monitoring is an economical non-invasive method which carries no risk. Spontaneous arrhythmias of sufficient frequency to be recorded during the monitoring period can be studied. When applied to VES, it provides quantitative rather than qualitative information despite classifications such as Lown's. The results should be analysed taking spontaneous variations of the arrhythmia into consideration. Holter monitoring may also reveal proarrhythmic drug effects (bradycardia, torsades de pointe). However, there are no absolute criteria of efficacy except total suppression of VES, unexplainable by spontaneous variability. Holter antiarrhythmic studies require stable VES which creates a bias in the evaluation of results due to the special selection of patients. Electrophysiological studies are costly, invasive and uncomfortable but they are the only way of assessing paroxysmal VT apart from clinical follow-up. This method is only applicable to inducible VT, which is the commonest form. The investigating protocols are specific and reproducible: a tachycardia which is non-inducible does not recur in 90% of cases, which enables prediction of the antiarrhythmic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

[Value and limitations of Holter monitoring and electrophysiologic testing in the evaluation of the treatment of sustained monomorphic ventricular tachycardia]

The authors studied the value and limitations of Holter monitoring and electrophysiological investigation in the evaluation of treatment of sustained monomorphic ventricular tachycardia (VT). One hundred and twenty-four consecutive patients were included in the study from January 1981 to February 1988. The etiologies were chronic myocardial infarction (N = 54), dilated cardiomyopathy (N = 24), right ventricular dysplasia (N = 31), and idiopathic VT (N = 15). All the tachycardias could be induced during baseline electrophysiological investigations and presented as complex ventricular arrhythmias on the Holter recordings. The investigations were repeated after treatment which was maintained irrespective of the results, unless the tachycardia which was induced or recorded was over 130 cycles/min and/or poorly tolerated. Recurrence was defined as the recording of VT in the absence of a change of treatment and/or the occurrence of sudden death. The follow-up period averaged 29 +/- 21 months. The Kaplan-Meier method was used to study the prevalence of absence of recurrence and survival rates. We observed 28 recurrences of VT and there were 21 deaths. Eighty-five per cent of patients had normal Holter monitoring after treatment. The prevalence of absence of recurrence was 0.751 when the Holter was normal and 0.485 when an arrhythmia was recorded (p = 0.03). The sensitivity was 25 per cent and the specificity 88 per cent. The survival rates were 0.66 and 0.585 respectively (p = 0.008). Fifty-three per cent of patients remained inducible after treatment with a prevalence of absence of recurrence of 0.572. This value rose to 0.877 when VT could not be induced (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Better predictors of successful His-bundle ablation analysis of first shocks

We have reported here that a longer HV interval in association with a larger His amplitude yields a high rate of success when used to position the ablating catheter for His-bundle ablation. Additionally, we have shown that double discharge shocks are more effective than single discharge shocks, and that negative polarity is more effective than positive polarity. The use of bipolar or tripolar, and not quadripolar catheters, was also associated with a higher success rate. In our institution, using a bipolar catheter, we attempt to record an HV interval greater than 55 msec and a His amplitude greater than 0.35 mV. When both of these criteria are fulfilled, we use 3 to 4 joules per kg, and a single discharge shock. When one or the other of these criteria are not fulfilled, we use the double discharge shock method. Using these techniques, we have achieved successful His-bundle ablation with only one shock in all but one of the most recent 21 consecutive patients.