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Biomedical subjects

J C Geller

Publications and source records attributed to J C Geller.

At least 19 recordsLinked to original sources

[Syncope in the elderly].

Age-related physiologic changes, a higher prevalence of chronic illness, and concomitant (often multiple) medication account for a higher susceptibility of elderly patients to syncope. Although elderly patients are the largest group with syncope, the causes frequently remain unclear. Multifactorial causes, lack of witnesses, overlap with falls, and additional cognitive impairment often confound the assessment of syncope in the elderly. Thus, strategic investigation is often needed to establish the diagnosis and to unmask the cause. In addition to a comprehensive medical history (by both patient and witnesses), a thorough physical examination including supine and standing blood pressure measurements and a standard 12 lead ECG remain the mainstay of diagnosis. The decision whether additional tests are needed depends on indications whether organic heart disease is present or not. Without evidence of structural heart disease, tilt table testing and studies of autonomic function are the next steps. In contrast, additional cardiac investigation (including invasive studies) is needed in patients with suspected or documented cardiac disease. External or implantable loop recorders represent a significant improvement in the diagnosis of rare episodes of (brady- or tachy)-arrhythmias. Prognosis is determined by the underlying (heart) disease.

Aged↗

[Transvenous parasympathetic nerve stimulation in the chronic myocardial infarction phase].

The study describes the electrophysiological effects of transvenous cardiac nerve stimulation in an animal model of myocardial infarction. In ten sheep with recent myocardial infarction, transvenous stimulation of parasympathetic cardiac nerves was achieved from a catheter in the right pulmonary artery. The effects of transvenous cardiac nerve stimulation on sinus rhythm cycle length, ventricular refractory periods and inducibility of monomorphic ventricular tachycardia were evaluated. Sinus rhythm cycle length increased from 620 +/- 24 ms to 723 +/- 30 ms during nerve stimulation with 20 Hz and to 779 +/- 28 ms during stimulation with 40 Hz (p < 0.05). Effective ventricular refractory periods from stimulation sites in non-infarcted right and left ventricular myocardium showed a tendency towards prolongation during cardiac nerve stimulation with shortening after cessation of stimulation. These differences, however, were not significant. In contrast, refractory periods from stimulation sites within the infarcted area remained unchanged during cardiac nerve stimulation. The inducibility of monomorphic ventricular tachycardia by programmed electrical stimulation was reduced during transvenous cardiac nerve stimulation. Pathological examination showed cholinergic nerves in close proximity to the tip of the stimulation catheter in the right pulmonary artery. Transvenous cardiac nerve stimulation in sheep with remote myocardial infarction exhibits electrophysiological effects on the ventricles. Although a parasympathetic effect on the ventricles could not be proven, the observed effects may result from direct stimulation of efferent parasympathetic nerves.

Animals↗

[Atrial fibrillation as end point of hypertension. Can antihypertensive therapy prevent it?].

The most effective and safest option for the prevention of atrial fibrillation and its sequelae--cardiovascular morbidity and mortality, stroke)--is primary prophylaxis. Here, the management of arterial hypertension--the most common cause underlying atrial fibrillation--is of considerable importance. In addition to blood pressure reduction, substances with an action of the autonomic nervous system and the renin-angiotensin-aldosterone system (ACE-inhibitors, AT1 antagonists, beta blockers) have a positive effect on the remodeling, so-called, of the atrial myocytes, and thus on the occurrence of atrial fibrillation with its associated stroke risk. For patients with elevated blood pressure, therefore, the therapeutic strategy should, in the individual case, give consideration to the possibility of exerting a positive effect on atrial fibrillation.

Adrenergic beta-Antagonists↗

Incremental programming of atrial anti-tachycardia pacing therapies in bradycardia-indicated patients: effects on therapy efficacy and atrial tachyarrhythmia burden.

AIMS: Efficacy of pace-termination of atrial arrhythmias (ATP) may depend on atrial cycle length and regularity. Whether device programming of ATP therapies can improve ATP efficacy and alter atrial tachyarrhythmia burden is unknown. METHODS AND RESULTS: ATP efficacy was evaluated in 61 patients (39 males; 66 +/- 10 years) with a standard indication for pacing, 95% with a history of AT/AF. Each patient was implanted with a novel DDDRP pacemaker capable of delivering ATP therapy. ATP efficacy and AT/AF frequency and burden were compared within each patient during a period of nominal ATP programming (NP) followed by a period of aggressive incremental programming (IP). Adjusted ATP-termination efficacy was higher during IP than during NP (54.8% vs 37.9%, P < 0.05). No differences in AT/AF frequency (3.3 +/- 5.9 vs 3.2 +/- 6.9 day(-1)) or burden (18 +/- 28% vs 18 +/- 29%) were observed comparing NP with IP. The majority of episodes during both the NP (81%) and IP (77%) periods terminated within 10 min. Episodes lasting 24 h or more accounted for only 0.4% of the episodes in both groups. but accounted for 38% of the average burden during NP and 51% during IP. CONCLUSIONS: Device programming of ATP therapies can influence the number of treated episodes and the efficacy of ATP therapies although arrhythmic frequency and burden may not change. Total atrial arrhythmia burden is disproportionately influenced by long (>24 h) episodes.

Aged↗

[The Wearable Cardioverter Defibrillator (WCD) for the prevention of sudden cardiac death -- a single center experience].

The Wearable Cardioverter Defibrillator (WCD) is an external defibrillator that automatically detects and treats ventricular tachyarrhythmias without the need for assistance from a bystander while at the same time allowing the patient to ambulate freely. The main components of the system are the defibrillator unit and a chest belt with electrodes for arrhythmia detection and therapy delivery. Between December 1998 and October 2001, 84 patients used the device at our institution. The majority of patients had a history of acute myocardial infarction or coronary artery bypass surgery with an increased risk for sudden cardiac death or were awaiting heart transplantation. During a mean follow-up of 116+/-90 days, 7 episodes of ventricular tachyarrhythmias were detected and terminated successfully by the WCD in 5 patients. In 9720 days, there was one inappropriate shock due to oversensing of electrical noise. Four patients died during follow-up; none of them had a cardiac arrest while wearing the device. Five patients were excluded because of irregularities in device use. An ICD was implanted in 24 patients at the end of the follow-up period. The WCD is effective in detecting and treating ventricular tachyarrhythmias in patients with an intermittently increased risk for sudden cardiac death. Further use of the system in larger patient populations is needed to confirm its safety and cost effectiveness.

Aged↗

Efficacy and safety of moricizine in the maintenance of sinus rhythm in patients with recurrent atrial fibrillation.

Maintenance of sinus rhythm is the primary goal of antiarrhythmic drug therapy for recurrent atrial fibrillation (AF). However, concern about proarrhythmic and negative inotropic effects has led to increasing reluctance to administer antiarrhythmic agents for this non-life-threatening arrhythmia. Moricizine is well tolerated in a wide variety of patients, and therefore, may be a safe and effective agent for treating AF. We retrospectively assessed the efficacy and safety of moricizine (mean dose 609 +/- 9 mg/day) in 85 consecutive patients with recurrent AF (2.6 +/- 0.5 years duration, 1.6 +/- 1 failed antiarrhythmic drugs). Structural heart disease was present in 69 (81%), but no recent myocardial infarct (< or =90 days) was present; mean left atrial size was 46 +/- 1 mm, and mean left ventricular ejection fraction was 0.51 +/- 0.01. Moricizine was discontinued because of unsuccessful direct-current cardioversion (n = 5) or clinically unacceptable side effects (n = 6); 6 patients developed transient side effects not requiring discontinuation. Of the 74 patients continuing therapy, 68% remained in sinus rhythm after 6 months, and 59% after 12 months. During a follow-up (21 +/- 2 months), there were neither deaths nor adverse effects requiring discontinuation of therapy. Thus, moricizine was effective, safe, and well tolerated in our patient cohort with AF.

Adult↗

Case report: severe skin burn at the site of the indifferent electrode after radiofrequency catheter ablation of typical atrial flutter.

Although radiofrequency (RF) catheter ablation has been shown to be an effective treatment strategy in patients with supraventricular tachycardia, RF ablation may lead to potentially serious complications. We describe a case of a 65-year old man who was transferred for catheter ablation of typical atrial flutter. 21 RF applications (mean energy: 81+/-9 watts) were applied in the temperature-controlled mode (70 degrees C) between a 8-mm tip electrode and an indifferent electrode using a high-power RF generator (100 watts) until bi-directional atrial isthmus block was achieved. After the procedure, a third-degree skin burn (10x2 cm) was observed at the lateral edge of the adhesive indifferent electrode whereas the medial edge of the electrode was not fully attached to the skin surface. This case is one out of 1128 ablation procedures (0.09 %) at our institution using a high-power RF generator. The present study demonstrates a severe skin burn induced by mal-attachment of an indifferent electrode during RF ablation. Long RF energy application times, high-power settings, and heavy sedation may have contributed to the observed severity of skin damage.

Aged↗

Regulation of angiotensin II receptor subtypes during atrial fibrillation in humans.

BACKGROUND: Previous studies have suggested that atrial fibrillation (AF) is associated with the activation of the atrial angiotensin system. However, it is not known whether the expression of angiotensin II receptors changes during AF. The purpose of this study was to determine the atrial expression of angiotensin II type 1 and type 2 receptors (AT(1)-R and AT(2)-R) in patients with AF. METHODS AND RESULTS: Atrial tissue samples from 30 patients undergoing open heart surgery were examined. Eleven patients had chronic persistent AF (> or =6 months; cAF), 8 patients had paroxysmal AF (pAF), and 11 patients were in sinus rhythm. AT(1)-R and AT(2)-R were localized in the atrial tissue by immunohistochemistry and quantified at the protein and mRNA level by Western blotting and quantitative polymerase chain reaction. Both types of AT-R were predominantly expressed in atrial myocytes in all groups. The amount of AT(1)-R was reduced to 34.9% during cAF (P<0.01) and to 51.7% during pAF (P<0.05) compared with patients in sinus rhythm. In contrast, AT(2)-R was increased during cAF (246%; P=NS) and pAF (505%; P<0.01). AT(1)-R/AT(2)-R mRNA content was similar in all groups. CONCLUSIONS: AF is associated with the down-regulation of atrial AT(1)-R and the up-regulation of AT(2)-R proteins. These findings may help define the pathophysiological role of the angiotensin system in the structural remodeling of the fibrillating atria.

Adult↗

Increased expression of extracellular signal-regulated kinase and angiotensin-converting enzyme in human atria during atrial fibrillation.

OBJECTIVES: The purpose of this study was to determine whether atrial expression of the extracellular signal-regulated kinases Erk1/Erk2 and of the angiotensin-converting enzyme (ACE) is altered in patients with atrial fibrillation (AF). BACKGROUND: Recent studies have demonstrated that atrial fibrosis can provide a pathophysiologic substrate for AF. However, the molecular mechanisms responsible for the development of atrial fibrosis are unclear. METHODS: Atrial tissue samples of 43 patients undergoing open heart surgery were examined. Seventeen patients had chronic persistent AF (> or =6 months; CAF), 8 patients had paroxysmal AF (PAF) and 18 patients had no history of AF. Erk expression was analyzed at the mRNA (quantitative reverse transcription polymerase chain reaction), the protein (immunoblot techniques) and atrial tissue (immunohistochemistry) levels. Erk-activating kinases (MEK1/2) and ACE were analyzed by immunoblot techniques. RESULTS: Increased amounts of Erk2-mRNA were found in patients with CAF (75 +/- 20 U vs. sinus rhythm: 31 +/- 25 U; p < 0.05). Activated Erk1/Erk2 and MEK1/2 were increased to more than 150% in patients with AF compared to patients with sinus rhythm. No differences between CAF and PAF were found. The expression of ACE was three-fold increased during CAF. Amounts of activated Erk1/Erk2 were reduced in patients treated with ACE inhibitors. Patients with AF showed an increased expression of Erk1/Erk2 in interstitial cells and marked atrial fibrosis. CONCLUSIONS: An ACE-dependent increase in the amounts of activated Erk1/Erk2 in atrial interstitial cells may contribute as a molecular mechanism for the development of atrial fibrosis in patients with AF. These findings may have important impact on the treatment of AF.

Aged↗

Changes in AV node conduction curves following slow pathway modification.

Dual AV node physiology often persists after successful slow pathway (SP) ablation, and the mechanism of tachycardia elimination is unresolved. Therefore, AV node conduction curves were analyzed following successful ablation (4 +/- 1 energy applications) in 85 consecutive patients (58 women, age 50 +/- 2 years) with typical AVNRT. Twenty-seven patients (32%) had complete elimination (group 1) whereas 58 (68%) patients had persistence (group 2) of dual AV node physiology. A significant increase in the AV node Wenckebach cycle length (WB-CL) was observed in both groups (310 +/- 9 to 351 +/- 15 ms in group 1, and 325 +/- 8 to 369 +/- 9 ms in group 2, P < 0.05). A decrease in the fast pathway (FP) ERP (339 +/- 15 to 279 +/- 12 ms) and an increase in the maximum FP AH interval (141 +/- 5 to 171 +/- 7) were observed only in group 1 (P < 0.05). In group 2, no change in the SP ERP (267 +/- 7 to 280 +/- 10 ms) was observed, and the change in the maximum SP-AH following ablation showed a significant inverse relation to the maximum SP-AH at baseline in group 2. In conclusion, (1) an increase in the WB-CL is observed independent of the persistence or elimination of dual physiology after successful ablation; (2) when dual physiology is eliminated, significant changes in the FP ERP and the maximum FP-AH occur; (3) when dual physiology persists, FP physiology and the SP ERP remain unchanged, and a significant inverse relation between the change in the maximum SP-AH following ablation and the maximum baseline SP-AH is observed.

Atrioventricular Node↗

Increased expression of P-selectin in patients with chronic atrial fibrillation.

Previous studies have shown that platelets are activated during atrial fibrillation (AF). However, prophylactic therapy with aspirin is not associated with a reduction of thromboembolic complications in patients with AF. Stimulation of platelet thrombin and ADP receptors causes a release of P-selectin, which is not affected by aspirin. The purpose of this study was to assess the influence of AF on platelet P-selectin expression. Blood samples from 30 patients were studied ex vivo. Nineteen patients had chronic AF (> 3 months), 11 patients were in sinus rhythm (SR). P-selectin expression was determined by flow cytometry (antibody binding capacity [BC]) at baseline and after platelet stimulation with adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP). To determine the effect of heart rate and atrial pressure (RAP), measurements were repeated after 10 minutes of ventricular pacing (120 beats/min) in patients with SR. P-selectin expression was increased in patients with AF at baseline (AF: 1329 +/- 81 BC vs SR: 968 +/- 108 BC; P < 0.05) and after stimulation with ADP (AF: 1445 +/- 101 BC vs SR: 1061 +/- 109 BC; P < 0.05) and TRAP (AF: 13,783 +/- 2442 BC vs SR: 5977 +/- 800 BC; P < 0.05). RAP (2.0 +/- 0.5 vs 6.0 +/- 0.8 mmHg; P < 0.01) and atrial rate (75 +/- 5 vs 114 +/- 5 beats/min; P < 0.001) increased during ventricular pacing. However, P-selectin levels remained stable. AF was accompanied by increased P-selectin expression. In contrast, increased ventricular rate and elevated atrial pressure alone had no effect on platelet activity. Further studies are needed to determine if platelet ADP receptor inhibitors offer a therapeutic benefit in patients with AF.

Adenosine Diphosphate↗

Persistent T-wave changes after radiofrequency catheter ablation of an accessory connection (Wolff-parkinson-white syndrome) are caused by "cardiac memory".

BACKGROUND: The purpose of this study was to determine the incidence and origin of T-wave changes after ablation of an accessory atrioventricular connection (AC), which could either be a sign of damage to the coronary circulation or a result of persistent abnormal repolarization secondary to previously abnormal ventricular activation ("cardiac memory"). METHODS AND RESULTS: Ninety of 107 consecutive patients (33 women and 57 men, mean age 36 +/- 5 years) undergoing successful catheter ablation of an AC were studied. Patients with bundle branch block or more than 1 AC were excluded. Sixty-four patients had manifest preexcitation (group 1) and 26 had a concealed AC (group 2). Immediately after loss of preexcitation, 38 (59%) patients with a manifest AC showed T-wave abnormalities. In contrast, none of the patients with a concealed AC had T-wave abnormalities after ablation (P <.05). The T-wave changes (1) did not correlate with the number or duration of energy applications or with markers of tissue injury; (2) correlated with the location of the AC and the degree of preexcitation, respectively; and (3) completely resolved over a period of weeks to months. None of the patients had recurrence of preexcitation or tachycardia during a mean follow-up of 16 +/- 7 months. CONCLUSIONS: T-wave changes after ablation are most likely caused by "cardiac memory" and are not a sign of myocardial or coronary injury.

Adult↗

New evidence that AV node slow pathway conduction directly influences fast pathway function.

INTRODUCTION: Shortening of the AV node fast pathway effective refractory period (ERP) following successful slow pathway ablation may be a nonspecific effect of energy application at the AV junction or may be due to elimination of a direct effect of slow pathway conduction on the fast pathway. METHODS AND RESULTS: Twenty-six consecutive patients (20 women and 6 men; mean age 45 +/- 3 years) with typical AV nodal reentrant tachycardia who underwent successful slow pathway ablation (defined as complete elimination of dual AV node physiology) were studied. The fast pathway ERP (at a drive train cycle length of 600 msec) was determined prior to ablation (baseline) and following unsuccessful and successful ablation attempts. Successful slow pathway ablation shortened the fast pathway ERP significantly (317 +/- 9 msec; P < 0.001) compared to baseline (386 +/- 12 msec), whereas unsuccessful ablations had no effect (376 +/- 11 msec). Sinus cycle length, the AH interval, and blood pressure were unchanged following successful ablation. Shortening of the fast pathway ERP did not correlate with the number of energy applications or with two measures of the proximity between the slow and the fast pathway. CONCLUSION: These results support the hypothesis that shortening of the fast pathway ERP following slow pathway ablation is due to elimination of a direct effect of slow pathway conduction on fast pathway function rather than a nonspecific effect of repeated energy delivery at the AV junction.

Adolescent↗