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Biomedical subjects

E Aliot

Publications and source records attributed to E Aliot.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Radiofrequency ablation of the atrioventricular accessory pathways. Value of unipolar and bipolar recordings].

Radiofrequency catheter ablation has become the treatment of choice of arrhythmias related to accessory atrioventricular pathways. The reported success rate is well over 90%, irrespective of the localisation of the accessory pathway, and serious complications are rare. A basic principle of the technique is the limitation of the number of applications of radiofrequency energy during a session of ablation and this requires mapping to determine the ideal site using various electrographic parameters. With regards to bipolar recordings, they include: the atrioventricular conduction time, localisation of the ventricular pole of the accessory pathway, recording the accessory pathway potential, the atrial pole of the accessory pathway, and stability of the catheter position. However, the parameters are not readily reproducible and the positive predictive value for successful ablation is low. The use of unipolar electrograms could therefore represent a fundamental step in improving the localisation of accessory pathways and thereby reducing the number of useless applications of radiofrequency energy.

Arrhythmias, Cardiac↗
PubMed1996

[Trandolapril in patients with left ventricular insufficiency after myocardial infarction].

The TRACE (TRAndolapril Cardiac Evaluation) study was designed to determine whether long-term treatment with an ACE inhibitor is beneficial in patients with early post-myocardial infarction cardiac failure. A total 6,676 consecutive patients with 7,001 myocardial infarctions were included; 2,606 patients had echocardiographic signes of left ventricular dysfunction (ejection fraction < 35%), 3 to 7 days after myocardial infarction; 1,749 patients were randomised and given either oral trandolapril (876 patients) or placebo (873 patients). Follow-up ranged from 24 to 50 months. Three hundred and four patients (34.7%) in the trandolapril group died, compared with 369 (42.3%) in the placebo group (p = 0.001). The relative risk of death in the trandolapril group compared with the placebo group was 0.78. Trandolapril was also associated with a statistically significantly lower risk of cardiovascular death and of sudden death. Progression to severe cardiac failure was also less frequent in the treatment group. On the other hand, the risk of recurrent myocardial infarction was not significantly reduced. In conclusion, long-term treatment with trandolapril in patients with early post-infarction left ventricular dysfunction significantly reduced the risk of cardiovascular mortality, sudden death and progression to severe cardiac failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

[Value of unipolar and bipolar recordings in radiofrequency ablation of accessory atrioventricular pathways].

The aim of the study was to compare the value of different modes of endocavitary recordings: unipolar alone, bipolar alone and the association of unipolar and bipolar recordings in radiofrequency ablation of accessory atrioventricular pathways. A retrospective analysis by three independent observers of 135 endocavitary recordings obtained immediately before radiofrequency application in 82 subjects who underwent radiofrequency ablation for symptomatic accessory atrioventricular pathways. In each case, the authors selected the "successful" record which corresponded to the final radiofrequency application and 0.1 or 2 records of "failures". Each initial recording being of 3 types (unipolar, bipolar and association of uni- and bipolar), a total of 390 anonymous and randomised recordings were analysed by the observers who determined whether the appearances indicated successful ablation. Univariate analysis of variants showed a correlation between success with the mode of recording (p = 0.03) and a left lateral position of the accessory pathways. In multivariate analysis, three variables remained correlated with successful ablation: the observer variable (p = 0.001), and two interactions observer - mode (p = 0.005) and observer-stability (p = 0.02). The benefits of the association of unipolar and bipolar recordings with respect to bipolar recording alone, seemed to be important in predicting failure. The results of tests of concordance in the group of failures were confirmatory: concordance between observers was only found between the unipolar mode alone and the association of unipolar and bipolar recordings. The results of this study suggest that the association of unipolar and bipolar endocavitary recordings may reduce the number of unnecessary application of radiofrequency energy by improved identification of recording showing failure.

Adult↗
PubMed1995

A study of biochemical markers of reperfusion early after thrombolysis for acute myocardial infarction. The PERM Study Group. Prospective Evaluation of Reperfusion Markers.

BACKGROUND: In acute myocardial infarction (AMI), early noninvasive identification of patients with occluded infarct-related arteries (IRAs) after thrombolysis has important prognostic and therapeutic implications. The aims of this study were to evaluate biochemical methods for the early diagnosis of patency after thrombolysis prospectively and to establish the optimal diagnostic criteria retrospectively. METHODS AND RESULTS: In 97 patients with AMI treated with thrombolytic agents < or = 6 hours after the onset of symptoms, myoglobin, troponin T, creatine kinase, the MB isoenzyme and MM isoforms of creatine kinase were measured just before thrombolysis began and 90 minutes later. IRA patency was assessed by means of 90-minute coronary angiography. For each marker, compared with the expected sensitivity and specificity based on published thresholds for the diagnosis of patency, the observed values were consistently lower but were markedly improved in a subset of patients treated > 3 hours after the onset of symptoms. With receiver-operator characteristic curve analysis of the slopes of increase and relative increases in each marker over 90 minutes, the best diagnostic performance was achieved by use of the relative increase in myoglobin, troponin T, and MM3/MM1 creatine kinase isoforms in patients treated > 3 hours after onset (areas under the curve of 0.84, 0.83, and 0.85, respectively). CONCLUSIONS: Effective early noninvasive diagnosis of patency after thrombolysis is possible in patients treated > 3 hours after symptom onset by use of criteria derived from the relative increase over 90 minutes in plasma markers, particularly myoglobin, troponin T, and MM3/MM1 creatine kinase isoforms. The diagnostic performance of the relative increase in myoglobin appears to be less susceptible to small changes in the diagnostic threshold value.

Biomarkers↗
PubMed1995

[Which patients at risk of sudden death after myocardial infarction? Critical study of prognostic factors].

A lot of acquired data concerning the prognostic factors of post-infarction mortality dates from the pre-thrombolysis era. This mortality has considerably decreased since the active management of the acute phase of myocardial infarction. This has made it more complex to evaluate the post-infarction electrical risk and may have reduced the need. However, it is not less true that the assessment of the post-infarction risk necessitates a study of each factor predisposing to severe ventricular arrhythmias and sudden death: myocardial ischaemia, left ventricular dysfunction and electrical instability. The latter parameter may be assessed by non-invasive (ventricular extrasystoles, late ventricular potentials, heart rate variability, the baroreflex and the QT interval) and invasive methods (programmed ventricular stimulation). The association of these results has an excellent negative predictive value, and also improves the positive predictive value which, nevertheless, remains insufficient for expensive prophylactic measures associated with a certain morbidity, for example the implantation of a defibrillator device, to be taken.

Death, Sudden, Cardiac↗
PubMed1995

[Atrial electrophysiological study of unexplained ischemic cerebrovascular disorders].

The aim of this study was to search for the presence of atrial vulnerability by programmed atrial stimulation in patients with unexplained ischaemic cerebrovascular strokes and to evaluate the effects of intravenous flecainide acetate on the electrophysiological parameters and on the induction of atrial arrhythmias. Thirty-eight patients (20 men, 18 women) with a mean age of 38.4 +/- 11 years were investigated. Programmed atrial pacing triggered a sustained (> 1 min) atrial arrhythmia with 1 or 2 extrastimuli in 23 of the 38 patients (61%), in these patients, there was a significant shortening of the effective refractory periods (ERP: 193 +/- 23 vs 218 +/- 30 ms; p < 0.02) and of the functional refractory periods (FRP: 228 +/- 25 vs 253 +/- 27 ms; p < 0.01) with lengthening of the A2 auriculogramme (99.7 +/- 22 vs 76.1 +/- 16 ms; p < 0.05). A combined study of the refractory periods and conduction defects provides a means of calculating an index of latent vulnerability which is greatly shortened when an atrial arrhythmia is induced (2 +/- 0.5 cm vs 3 +/- 0.6 cm; p < 0.001). Atrial arrhythmias could not be initiated after intravenous 3 mg/kg of flecainide acetate in 4 subjects (17%) with initially positive atrial stimulation tests. This study confirms the high frequency of atrial vulnerability in patients with unexplained ischaemic cerebrovascular strokes. In their population, the authors observed a low efficacy of flecainide acetate in the prevention of reinduction of atrial arrhythmias. The indication of long-term antiarrhythmic drugs in these patients are questionnable and should be assessed by a prospective long-term multicentre trial.

Adult↗
PubMed1994

Contribution of specific skeletal muscle metabolic abnormalities to limitation of exercise capacity in patients with chronic heart failure: a phosphorus 31 nuclear magnetic resonance study.

Several studies of phosphorus 31 (31P) magnetic resonance spectroscopy (MRS) have demonstrated the presence of skeletal muscle metabolic abnormalities during exercise in patients with chronic heart failure (CHF). We studied the contribution of these abnormalities to the limitation of exercise capacity in CHF. In 25 patients (age 57 +/- 2 years, left ventricular ejection fraction [LVEF] 28% +/- 1.6%, peak oxygen consumption (VO2) 16 +/- 1.2 ml/kg/mm) (mean +/- SEM), we studied the calf muscle at rest and during plantar flexion with 31P MRS. The phosphocreatine (PCr) depletion rate was significantly negatively correlated to peak VO2 (r = -0.62, p = 0.001) but not to LVEF. Muscle pH was correlated with the inorganic phosphorus (Pi)/PCr ratio (r = -0.69, p = 0.0001) and with the PCr/adenosine triphosphate beta (ATP beta) ratio (which negatively relates to adenosine diphosphate [ADP] concentration) (r = 0.65, p = 0.00001). Although muscle ATP (ATP/sum of phosphorus [sigma P] remained stable, in 8 patients ATP/sigma P decreased significantly (-15% +/- 4%, p = 0.0002). In this ATP-depleted group, peak VO2 was significantly lower than that of the nondepleted group and PCr depletion more rapid, whereas LVEF did not differ. Skeletal muscle metabolic abnormalities in CHF contribute markedly to the alteration of exercise capacity. Rapid PCr depletion and muscle acidosis are the most relevant abnormalities. ATP depletion and excessive increase in ADP during exercise may contribute further to exercise limitation specifically in patients with more marked CHF.

Adenosine Diphosphate↗
PubMed1994

Abnormal coronary flow velocity pattern in patients with left ventricular hypertrophy, angina pectoris, and normal coronary arteries: a transesophageal Doppler echocardiographic study.

Previous invasive studies have suggested that coronary flow reserve is impaired in patients with left ventricular hypertrophy (LVH) and symptoms of ischemia. We tested whether transesophageal Doppler, a semiinvasive technique, can detect altered characteristics of baseline coronary blood flow velocity in such patients. Thirty patients with LVH (hypertrophic cardiomyopathy in 4, aortic stenosis in 17, hypertension in 9) were studied. Fourteen patients had asymptomatic LVH. Sixteen patients had clinical symptoms of ischemia with angiographically normal epicardial coronary arteries. Ten subjects with no cardiovascular disease were studied as a control group. Peak diastolic and systolic coronary flow velocities were recorded in the proximal part of the left anterior descending artery (LAD) with the use of pulsed Doppler guided by color flow imaging. Patients with symptomatic LVH had higher diastolic peak coronary flow velocity (81 +/- 10 cm/sec, p = 0.0001) compared with normal subjects (41 +/- 8 cm/sec) and patients with asymptomatic LVH (44 +/- 8 cm/sec). In patients with asymptomatic LVH the diastolic coronary flow velocity/indexed ventricular mass ratio was lower (0.28 +/- 0.09 cm/gm/m2, p = 0.0001) compared with symptomatic patients (0.52 +/- 0.12 cm/gm/m2) and compared with controls (0.47 +/- 0.16 cm/gm/m2). Patients with symptomatic LVH but no aortic stenosis also had higher peak systolic coronary flow velocity (38 +/- 9 cm/sec) compared with the other groups (p = 0.0001). In the group of patients with aortic stenosis a significant inverse linear relation was found between peak systolic coronary flow velocity and peak pressure gradient (r = -0.60, p 0.01). In conclusion, patients with symptomatic LVH have abnormally high baseline coronary flow velocities resulting in magnified intimal shear stress. Because flow velocity equals flow/vessel cross-sectional area, it is suggested that high coronary flow velocities in patients with symptomatic LVH result from both augmented coronary flow and failure of the vessel to enlarge commensurately with the increase in LV mass (relative functional stenosis). In patients with aortic stenosis, peak systolic coronary flow velocity appears to be influenced by transvalvular pressure drop.

Adult↗
PubMed1994

Skeletal muscle phosphate metabolism abnormalities in volume-overload experimental heart failure.

We studied skeletal muscle phosphate metabolism abnormalities to examine their contribution at an early stage of congestive heart failure (CHF) in rats with aortocaval fistula (ACF) 4 wk after the procedure. In a group of 26 rats (13 with ACF and 13 sham operated), we assessed the degree of CHF. The ACF produced a significant rise in heart weight and plasma atrial natriuretic peptide. In a second group of 26 rats (13 ACF and 13 sham operated), we performed 31P-magnetic resonance spectroscopy in the gastrocnemius muscle during motor activity produced by electrical stimulation. The rate of phosphocreatine depletion, expressed by its initial slope, was higher in the ACF rats compared with controls (0.078 +/- 0.01 vs. 0.041 +/- 0.007; P < 0.03). pH and ATP decreased and phosphodiesters increased in all rats during electrical stimulation, with no difference between ACF rats and controls. The kinetics of phosphocreatine recovery were not different between ACF rats and controls. Together with previous studies, our present results suggest that muscle metabolism abnormalities in CHF may vary according to the experimental model and may be observed early in the course of the disease.

Adenosine Triphosphate↗
PubMed1994

[Coronary artery surgery after 70 years: an analysis of the risk factors of operative mortality].

The risk factors of operative mortality after coronary bypass surgery in patients over 70 years of age were studied in a consecutive series of 109 patients operated in our department between January 1990 and June 1992. The anginal pain was classified stage III or IV in 92 cases. Seventy-nine patients had triple vessel disease, 36 patients had left main stem stenosis and 57 had previous myocardial infarction. Twenty-six patients had ejection fractions of less than 50% and 6 were less than 30%. The average number of bypass grafts was 2.35. Associated procedures included 9 endarteriectomies of the left main coronary, one endarteriectomy of the left anterior descending and right coronary arteries, 2 myotomies involving the left anterior descending artery, 3 ventricular remodeling procedures and 3 carotid endarteriectomies. Non-lethal postoperative complications were mainly pulmonary infections (19 cases). The operative mortality was 5.1% in the group with stable angina. On the other hand, the mortality was 31.2% in the group with unstable angina operated as an emergency or semi-emergency. The causes of death were mainly postoperative low output states (16 cases) and polyarteriopathy (mesenteric infarction: 6 cases). Although age was related to operative risk, the main prognostic factor was the preoperative cardiovascular status. The degree of emergency, unstable angina, left main coronary disease, duration of cardio-pulmonary bypass and the necessity for inotropic or mechanical support in the postoperative phase were significant risk factors for death. Sex, cardiovascular risk factors, previous myocardial infarction and duration of aortic clamping were not correlated to mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1994

[Influence of gender and size on parameters measured by signal-averaged electrocardiography in healthy subjects: preliminary study].

The aim of this study was to determine the influence of electrocardiographic and biomorphometric factors on the parameters measured by signal averaged electrocardiography (SA-ECG) in normal subjects. The study population comprised 40 Caucasian students (20 men, 20 women). The SA-ECG measured 6 parameters: total duration of the averaged QRS, the root mean square of the voltage of the last 40 ms of the QRS (RMS 40) and the length duration of the terminal signal of under 40 microV (LAS), each parameter being measured with a band pass filter of 25 and 40 Hz. The echocardiographic recording included measurement of 12 parameters including left ventricular mass and ventricular volumes. Five morphological parameters were measured, including height, weight and body surface area. The duration of QRS measured with a 25 Hz band pass filter was significantly longer by 9.7 ms in men than in women (102.9 +/- 8.5 ms versus 93.2 +/- 8.1 ms; p < 0.001). Similarly, QRS duration measured with the 40 Hz band pass filter was longer in men by 11.4 ms than in women (102.1 +/- 9.6 ms versus 90.7 +/- 7.5 ms; p < 0.001). Multiple linear regression analyses showed that in both men and women, the duration of the QRS measured with either a 25 or 40 Hz band pass filter was correlated to size: the taller the subject, the longer the QRS duration. A negative correlation was observed between size and RMS 40 measured with both 25 and 40 Hz band pass filters: the taller the subject, the smaller the value of RMS 40.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Value of permanent cardiac pacing in hypertrophic and obstructive cardiomyopathies resistant to medical treatment].

The authors report their experience of long-term dual-chamber pacing in the treatment of hypertrophic and obstructive cardiomyopathy. Between August 1990 and March 1993, 16 patients (8 men, average age 53.5 +/- 18.9 years, range 21 and 79 years) with symptomatic hypertrophic obstructive cardiomyopathy resistant to medical therapy underwent electrophysiological investigation to assess atrioventricular conduction and the effects of temporary atrioventricular pacing on the intraventricular pressure gradient before implantation of a dual-chamber pacing system. The decision to implant was taken if the endocavitary studies showed severe atrioventricular conduction defects and/or if temporary pacing reduced the systolic pressure gradient by more than 30%. Temporary dual-chamber pacing led to a decrease of 48% of the systolic pressure gradient from 78.6 +/- 21.3 to 40.1 +/- 23.6 mmHg (p < 0.0005), a regression observed in 15 of the 16 patients. After an average follow-up period of 18.7 +/- 9.5 months (range 6 and 37 months), all 15 patients who received a dual-chamber pacing system were alive and were clinically improved. The systolic pressure gradient continued to decrease during the follow-up period (24.4 +/- 17.2 mmHg at the 6th month compared with 36.5 +/- 18.6 mmHg at the time of implantation; p = 0.014). The clinical improvement was dependent on careful adjustment of the atrioventricular delay which was programmed at relatively short values (65.6 +/- 14 ms, range 47 and 75 ms) to obtain permanent right ventricular capture. The authors conclude that dual-chamber pacing is an effective means of treating symptomatic hypertrophic obstructive cardiomyopathy resistant to medical therapy, even in the absence of preexisting conduction defects.

Adult↗
PubMed1994

[Results, complications and long-term follow-up of percutaneous ablation of atrioventricular conduction. Apropos of 85 cases].

This retrospective study reports the immediate and long-term results of percutaneous ablation of atrioventricular conduction. Between July 1983 and January 1992, 85 consecutive patients (51 men, age 64 +/- 10 years, range 43-84 years) presenting with supraventricular arrhythmias (atrial fibrillation n = 53; atrial flutter n = 50; atrial tachycardia n = 17; junctional tachycardia n = 6) resistant to antiarrhythmic therapy (number of drugs used: 4 +/- 1.3, range 1-6) underwent interruption of atrioventricular conduction by fulguration (n = 65) or radiofrequency energy (n = 13) or by an association of the two methods (n = 7). The 75 pacemakers implanted (10 patients had pacemakers before the procedure) comprised 55 VVIR, 11 VVI, 5 DDD and 4 DDDR units. The immediate results included two sudden deaths at the 4th and 7th day in patients undergoing fulguration and three complications with a favourable outcome (staphylococcal septicaemia, pulmonary embolism and haematoma at the site of implantation of the pacemaker). None of the patients was lost to follow-up and the average follow-up was 31 +/- 18 months (range 2-108 months). During follow-up, 15 patients died and there was a recurrence of symptoms in 11 patients after 1 to 9 months requiring a repeat procedure. In the 68 survivors, the follow-up is now 38 +/- 18 months (range 12-108 months). Sixty one patients have 2nd (2) or 3rd (59) degree atrioventricular block, giving 90% good electrocardiographic results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Clinical aspects of implantable defibrillators: indication].

The rapidity of technological progress has now made available a device which was only a dream a few years ago, a nearly ideal implantable defibrillator. Despite the persistence of a number of technical and clinical problems, the fourth generation defibrillators are multiprogrammable, with antitachycardia and antibradycardia functions, implantable by the endocavitary approach in most cases thanks to the introduction of biphasic shocks, fitted with constantly improving systems of telemetry, and are progressively smaller in size. The selection of a defibrillator device requires consideration of the patient's needs and the technical characteristics of the defibrillator. Apart from special situations in which the indications of the implantable defibrillator are generally accepted, it is only possible in the absence of results of prospective clinical trials, to use data accumulated on the place of defibrillation compared with other forms of management of severe ventricular arrhythmias. As there is a wide choice of treatment of these ventricular arrhythmias, the role of each must be defined for each individual patient. With regards to the implantable defibrillator, it is essential to take into consideration a number of clinical and paraclinical factors such as the clinical preservation of the arrhythmia, the underlying cardiac disease, left ventricular function and the type of arrhythmia induced by programmed ventricular stimulation.

Arrhythmias, Cardiac↗
PubMed1994

[Left-sided His bundle ablation after failure of right-sided approach: technique and initial results].

Although interruption of atrioventricular conduction has been widely used over the last decade in patients with supraventricular arrhythmias and rapid conduction resistant to antiarrhythmic therapy, the incidence of atrioventricular block obtained by delivering the energy at the tricuspid ring ranges from 45 to 92%. Failure of this technique is usually related to the inhability to record endocavitary electrogrammes compatible with probable success by the right-sided approach. The authors report four cases of interruption of atrioventricular conduction in 4 men (average age 61.5 +/- 10 years) by the retrograde arterial catheterisation after one or more (1 to 3) failures by the right-sided approach. After arterial puncture, the ablation catheter is positioned against the interventricular septum below the aortic cusps to record the His bundle electrogram. His bundle ablation was obtained after an average of 2 radio frequency energy applications (range 1 to 3). At the time of effective application, the average amplitude of the endocavitary electrogram was as follows: auriculogram 0.09 mV (range 0.05 to 0.2 mV), His bundle electrogram 0.19 mV (0.15-0.22 mV), ventriculogram 1.36 mV (1.0 to 1.7 mV). No complications were observed. After an average follow-up of 4 months, the 4 patients were still in complete atrioventricular block. This preliminary series shows that left-sided interruption of atrioventricular conduction is effective and safe. It may be proposed after failure of a right-sided attempt.

Aged↗
PubMed1993

Noninvasive assessment of coronary flow dynamics before and after coronary angioplasty using transesophageal Doppler.

Recent invasive studies using intracoronary Doppler catheters or guide wires reported improved coronary flow dynamics after successful percutaneous transluminal coronary angioplasty. Transesophageal Doppler enables the measurement of coronary flow velocities within the left anterior descending artery. The present study was designed to test: (1) whether transesophageal Doppler may detect coronary flow velocity changes in patients undergoing angioplasty for left anterior descending artery stenosis, and (2) whether this technique may help to evaluate non-invasively the results of the procedure. Twenty-three patients undergoing angioplasty of the left anterior descending artery were studied by transesophageal Doppler before and < or = 24 hours after the interventional procedure. Coronary flow velocities were measured in the proximal part of the left anterior descending artery with the use of pulsed Doppler guided by color flow imaging. The degree of stenosis was measured by computerized quantitative coronary arteriography. Coronary flow velocity signals were successfully obtained in 19 of 23 patients (83%). In 16 successful angioplasty procedures, peak diastolic velocity increased from 37 +/- 14 cm/s before angioplasty to 51 +/- 16 cm/s after (p = 0.0001). In the 3 patients in whom angioplasty was unsuccessful, transesophageal Doppler showed no significant increase in peak diastolic coronary flow velocity. In a total of 19 angioplasty procedures, a good linear relation was found between the percent changes in coronary flow diastolic velocity and the reduction in the degree of stenosis (r = 0.85; p = 0.0001). All patients with > 20% increase in peak diastolic velocity had > 40% stenosis reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

[Atrial activity and its effects].

The initiation of cardiac impulse is located in the sinus node, in the upper anterior part of the right atrium. The importance of the atrium is not only linked to the regulation of heart rate, but also to its haemodynamic function. Indeed, atrial depolarization leads to atrial contraction which can be responsible for up to 30% of cardiac output by way of ventricular filling. Supraventricular arrhythmias are related to one of the following mechanisms: abnormal automaticity, triggered activity, and reentry. Most of supraventricular tachycardias are due to a reentrant phenomenon (intranodal reentrant tachycardia, orthodromic circusmovement tachycardia, atrial flutter and atrial fibrillation). At the onset of a supraventricular tachycardia, the loss of efficacious atrial contraction as well as the increased heart rate may abruptly decrease ventricular filling. As a consequence, stroke volume is reduced, leading to a decrease in cardiac output and in arterial blood pressure, explaining that the patient may experience syncope. Usually, blood pressure reduction resumes within 30 seconds after activation of the autonomic adrenergic nervous system. In case of an underlying heart disease, the supraventricular tachycardia may lead to acute cardiac failure. When reentry is concerned, the tachycardia is going around a specific circuit. The existence of such a circuit in most of supraventricular tachycardias has led to the development of ablation therapy, the goal of which is to destroy a critical portion of the circuit hence making the recurrence of reentrant tachycardia impossible.

Arrhythmias, Cardiac↗