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Biomedical subjects

A S Manolis

Publications and source records attributed to A S Manolis.

At least 73 records · Page 4Linked to original sources
PubMed1990

Syncope: current diagnostic evaluation and management.

OBJECTIVE: To provide a comprehensive review of the causes, current diagnostic evaluation, and treatment of syncope. DATA IDENTIFICATION: New data and knowledge in this evolving field were critically analyzed by doing a MEDLINE search on syncope supplemented by selective review of English language literature citations in the Index Medicus before 1980. STUDY SELECTION: We reviewed approximately 200 published articles on syncope and closely related topics as well as using our own clinical experience. We selected articles if they addressed the pathophysiology of syncope, classification and causes, differential diagnosis, noninvasive and invasive evaluation, and current therapy. RESULTS OF DATA SYNTHESIS: Syncope is a common clinical problem, occurring in 30% to 50% of the adult population. The prognosis for syncope depends on its cause. Cardiac syncope has the worst prognosis and therefore mandates thorough evaluation and prompt treatment. Diagnostic evaluation is made difficult by the transient nature of the episodes and the many causes. Noninvasive testing reveals the cause of syncope in approximately 50% of cases. More extensive evaluation, including invasive electrophysiologic studies, has assumed a larger role in defining the cause of syncope in selected patients with structural heart disease in whom a noninvasive evaluation has been nondiagnostic. Recently tilt-table studies have been proposed as a clinically useful noninvasive test for vagally mediated syncope. CONCLUSIONS: A rational stepwise diagnostic and therapeutic approach to patients with syncope can be developed by initially doing a careful history and physical examination followed by a noninvasive evaluation and selective use of additional, more specialized or invasive tests. Future research should focus on defining the validity and utility of current diagnostic testing in syncope and on exploring further the pathophysiology of patients with recurrent, unexplained syncope.

Cardiovascular Diseases↗
PubMed1990

Value of programmed ventricular stimulation in the evaluation and management of patients with nonsustained ventricular tachycardia associated with coronary artery disease.

Programmed ventricular stimulation with up to 3 extrastimuli at the right ventricular apex was performed in 52 patients with spontaneous nonsustained ventricular tachycardia (VT) associated with coronary artery disease. There were 44 men and 8 women, aged 66 +/- 9 years (range 45 to 86). The mean left ventricular ejection fraction was 41 +/- 14%. Nonsustained VT was asymptomatic in 10 patients (19%), while the arrhythmia was detected during evaluation of palpitations in 5 patients (10%), presyncope in 11 (21%) and syncope in 26 patients (50%). All patients were tested in the drug-free state and were classified as having no inducible arrhythmia (31 patients, group I), or an inducible arrhythmia (21 patients, group II). The age, gender, type of heart disease, symptoms and left ventricular ejection fraction were similar in both groups. Group I patients had a higher overall incidence of syncope. Group I patients received no therapy, while group II patients received antiarrhythmic therapy guided by electropharmacologic testing. At 21 +/- 17 months there was no sustained VT in either group. There were 3 deaths in group I patients, including 1 sudden, 1 nonsudden cardiac and 1 noncardiac death. In group II patients 6 deaths occurred including 4 nonsudden cardiac and 2 noncardiac deaths. In patients with nonsustained VT and coronary artery disease undergoing programmed ventricular stimulation, the incidence of significant arrhythmic events is low in those without therapy with no inducible arrhythmia, and in those with an inducible arrhythmia with therapy guided by electrophysiologic testing.

Anti-Arrhythmia Agents↗
PubMed1990

Randomized double-blind study of intravenous tocainide versus lidocaine for suppression of ventricular arrhythmias after cardiac surgery.

To compare the therapeutic efficacy and safety of intravenous tocainide with that of intravenous lidocaine in patients with ventricular arrhythmias after cardiac surgery, 25 patients were randomized to either agent in a double-blind manner. Tocainide was given in 16 patients as a 250 mg bolus followed by a loading infusion of 500 mg over 15 minutes and a maintenance infusion of 33.3 mg/min. Lidocaine was administered in 9 patients as a 100 mg bolus followed by a loading infusion of 60 mg over 15 minutes and a maintenance infusion of 1.4 mg/min. Therapy was continued for 24 hours in initially responding patients. With analysis of 24-h taped electrocardiograms it was found that single premature ventricular complexes (PVCs) were suppressed by tocainide by more than 80% in 94% of patients and by lidocaine in 75% of patients (p = NS). Couplets and ventricular tachycardia events were eliminated in all patients by either drug. Multiform PVCs were abolished in 94% of the patients after tocainide and in 75% after lidocaine (p = NS). Average overall success over the 24 hours with more than 80% suppression of single PVCs and simultaneous elimination of higher forms of arrhythmia was 71% with tocainide and 59% with lidocaine (p = NS). Adverse effects were negligible, with only one patient in the lidocaine group developing diaphoresis without necessitating termination of therapy. Treatment rapidly produced and then maintained blood levels of 4-10 mg/l for tocainide and 1-4 mg/l for lidocaine. We conclude that intravenous tocainide is well tolerated and has comparable efficacy to lidocaine in the acute therapy of postcardiac surgery ventricular arrhythmias.

Adult↗
PubMed1990

Mexiletine: pharmacology and therapeutic use.

Mexiletine is a Class IB antiarrhythmic which has basic and clinical electrophysiologic properties similar to lidocaine. Like other Class I antiarrhythmic agents, mexiletine blocks the rapid inward sodium current responsible for phase 0 of the action potential. It has been noted in the clinical electrophysiology laboratory to have minimal effect on sinus node function and AV nodal and His-Purkinje system conduction. Pharmacokinetic studies have shown that oral absorption is rapid with bioavailability of 80-90%. Mexiletine is predominantly metabolized by the liver with elimination half-life of 9 to 12 hours. The antiarrhythmic effects of the primary drug's metabolites remain to be defined. Hemodynamic studies have shown mexiletine to have a lesser negative inotropic effect than procainamide or disopyramide. Although mexiletine as a single agent successfully suppresses 60 to 80% of spontaneous ventricular arrhythmias, it has lower efficacy in suppression of induced ventricular arrhythmias. Multiple studies have shown that as monotherapy mexiletine is effective in preventing the induction of ventricular tachycardia in approximately 20% of patients. When used in combination with a Class IA antiarrhythmic drug for suppression of induced ventricular arrhythmias, multiple investigators have reported greater efficacy. Neurological side effects (tremor, dizziness, memory loss) occur in approximately 10% of patients while gastrointestinal side effects (nausea, anorexia, gastric irritation) occur in up to 40% of patients. Proarrhythmia or other serious toxicity from the drug is uncommon.

Anti-Arrhythmia Agents↗
PubMed1990

Apical hypertrophic cardiomyopathy presenting with sustained monomorphic ventricular tachycardia and electrocardiographic changes simulating coronary artery disease and left ventricular aneurysm.

A 52-year-old male presented with sustained monomorphic ventricular tachycardia as the initial manifestation of apical hypertrophic cardiomyopathy. The electrocardiogram during normal sinus rhythm showed a pattern of an old anterior wall myocardial infarction with aneurysm formation. Cardiac catheterization documented angiographically normal coronary arteries. Apical hypertrophic cardiomyopathy was documented at cardiac catheterization and by echocardiogram and Doppler studies. Monomorphic ventricular tachycardia was reproducibly initiated and terminated during electrophysiological studies and antiarrhythmic drugs failed to control the tachycardia. At the time of implantation of a cardioverter defibrillator, left ventricular apical biopsy revealed pathologic findings characteristic of hypertrophic cardiomyopathy.

Cardiomyopathy, Hypertrophic↗
PubMed1989

Automatic implantable cardioverter defibrillator. Current status.

The automatic implantable cardioverter defibrillator was conceived by Mirowski as an implantable device for detection and termination of ventricular fibrillation. Since the initial human implant of the defibrillator in 1980, there has been a dramatic expansion of the clinical experience with more than 5000 implants. The technology of the device, which is now capable of sensing and terminating both ventricular tachycardia and fibrillation, has evolved rapidly. Although still not an ideal antiarrhythmic device, it has already had a major impact on arrhythmic mortality with a marked reduction in the sudden death rates in a high-risk patient population.

Arrhythmias, Cardiac↗
PubMed1989

Reversal of electrophysiologic effects of flecainide on the accessory pathway by isoproterenol in the Wolff-Parkinson-White syndrome.

To determine the reversibility of the effects of flecainide on accessory pathways, electrophysiologic studies were performed in the drug-free control state, after flecainide loading and with isoproterenol infusion during flecainide treatment in 12 patients with symptomatic preexcitation syndrome. After the baseline drug-free evaluation, oral flecainide was given in dosages of 50 to 200 mg twice daily (mean daily dose 282 +/- 75) for at least 4 days before the repeat electrophysiologic study. Isoproterenol infusion was given in dosages of 1 to 4 micrograms/min to increase the heart rate at rest by 50%. Anterograde block in the accessory pathway was observed in 3 patients with flecainide therapy, whereas in the other patients the anterograde refractory period increased from 243 +/- 20 to 315 +/- 23 ms (p less than 0.05). The shortest preexcited RR interval during atrial fibrillation lengthened from 234 +/- 27 ms before flecainide to 313 +/- 38 ms (p less than 0.05). Retrograde block occurred in 2 patients after flecainide, whereas the retrograde refractory period of the accessory pathway increased from 247 +/- 26 to 337 +/- 45 ms in the other patients. Orthodromic atrioventricular reciprocating tachycardia, inducible in 10 patients before therapy, became noninducible in 3 patients. Its rate was significantly slowed in the other 7 patients (from 346 +/- 50 to 471 +/- 81 ms). In 2 patients the tachycardia was nonsustained during flecainide treatment. Atrial fibrillation, inducible in all patients at baseline, was rendered nonsustained and more difficult to induce in 7 patients with flecainide. When isoproterenol was infused during flecainide treatment, complete anterograde (3 patients) or retrograde block (2 patients) persisted in the accessory pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Prognostic value of early electrophysiologic studies for ventricular tachycardia recurrence in patients with coronary artery disease treated with amiodarone.

Amiodarone was used in 86 patients with ventricular tachycardia (VT) (67 patients) or ventricular fibrillation (19 patients) secondary to coronary artery disease. The mean +/- standard deviation left ventricular ejection fraction was 30 +/- 12% (range 8 to 65%). Prior trials with 4 +/- 1.2 alternate antiarrhythmic agents had been unsuccessful. Amiodarone was loaded at dosages of 1,200 to 1,800 mg/day, with maintenance dosages of 400 to 600 mg/day. Drug efficacy was evaluated by programmed stimulation at 10 to 14 days in 68 patients. In 38 patients sustained VT or ventricular fibrillation was inducible (group I), whereas 30 patients (group II) had either no inducible VT (8) or had nonsustained VT induced (22). Holter monitoring was used to assess drug efficacy in 18 patients (group III). All patients were evaluated at 3- to 6-month intervals with Holter monitors for efficacy and a standard protocol for toxicity. During a long-term follow-up of 18 +/- 16 months, sudden death occurred in 5 patients and nonfatal arrhythmia recurrences were detected in 16. The actuarial probability of freedom from fatal and nonfatal arrhythmia recurrences at 24 months was 0.52 for group I, 0.97 for group II and 0.68 for group III. The mode of induction, rate change or hemodynamic tolerance of the induced ventricular tachycardia did not predict arrhythmia recurrence. Among the clinical variables analyzed, only an ejection fraction of less than or equal to 30% was identified as a significant predictor of arrhythmia recurrence. Nonsudden cardiac death occurred in 21 patients, including 19 from heart failure and 2 from myocardial infarction. Noncardiac death occurred in 7 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

External cardiac programmed stimulation for noninvasive termination of sustained supraventricular and ventricular tachycardia.

To examine the feasibility of using a noninvasive temporary pacemaker for termination of well-tolerated supraventricular (SVT) and ventricular tachycardia (VT), a standard external demand pacemaker was modified to allow stimulation with single or multiple extrastimuli and overdrive pacing. To evaluate the efficacy, safety and tolerance of external cardiac programmed stimulation, a standard arrhythmia termination protocol was used in 223 tachycardias in 22 patients. The technique of external cardiac programmed stimulation was used in 209 episodes of SVT in 13 patients. It terminated 95% of the episodes with success in 19 of 20 episodes of atrioventricular nodal reentrant tachycardia and 179 of 189 episodes of atrioventricular reciprocating tachycardia. Of 198 episodes of SVT terminated by the technique 168 (85%) were terminated by a single extrastimulus and 28 (14%) by double extrastimuli. Only 2 episodes of SVT required overdrive pacing for termination. External cardiac programmed stimulation did not result in atrial fibrillation or arrhythmia acceleration. Of 14 episodes of sustained monomorphic VT 5 were terminated by external cardiac programmed stimulation. One tachycardia was terminated by a single extrastimulus, 1 by double extrastimuli and 3 by overdrive pacing. Arrhythmia acceleration occurred once and was terminated by endocardial pacing. On 27 separate occasions patient evaluation of maximal discomfort included 4 ratings of mild, 10 of moderate, 11 of severe and 2 of intolerable discomfort. External cardiac programmed stimulation is effective and safe in patients with well-tolerated sustained supraventricular or ventricular arrhythmias.

Adult↗
PubMed1989

Clinical experience in seventy-seven patients with the automatic implantable cardioverter defibrillator.

Seventy-seven patients with drug-refractory sustained ventricular tachycardia (VT) (28 patients) or ventricular fibrillation (VF) (49 patients) underwent implantation of an automatic cardioverter defibrillator (AICD). The 67 men and 10 women, with a mean age of 60 +/- 12 years (range 18 to 79), had coronary artery disease (60 patients), idiopathic cardiomyopathy (eight patients), mitral valve prolapse (four patients), hypertensive heart disease (one patient), Ebstein's anomaly (one patient), long QT syndrome (one patient), and primary electrical disease (two patients). The mean left ventricular ejection fraction was 35 +/- 16% (range 10% to 75%). Sustained VT/VF was induced in 64 patients (83%) at baseline electrophysiologic testing. A mean of 4.1 +/- 1.3 antiarrhythmic drugs failed to control the arrhythmia. Associated surgery at AICD implantation included coronary artery bypass in 19 patients, coronary bypass with aneurysmectomy in six patients, and aneurysmectomy alone in one patient. Five patients had only prophylactic patches implanted during aneurysmectomy or coronary bypass and the AICD device was subsequently implanted under local anesthesia to prevent arrhythmia recurrence or to control persistently inducible VT. Operative mortality was 2.6% with two deaths from intractable VF. Fifty-two patients (69%) continued receiving antiarrhythmic drugs to suppress spontaneous VT. During a mean follow-up of 15 +/- 13 months (range 1 to 63), six patients died: two suddenly due to probable pulse generator failure (greater than 2 years old), one of acute myocardial infarction, two of heart failure, and one of respiratory failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1989

Therapeutic serum lidocaine and metabolite concentrations in patients undergoing electrophysiologic study after discontinuation of intravenous lidocaine infusion.

Serum concentrations of lidocaine and its metabolites monoethylglycinexylidide (MEGX) and glycinexylidide (GX) were measured in seven patients after discontinuation of intravenous lidocaine necessary for control of spontaneous arrhythmias prior to electrophysiologic study. Standard loading doses of lidocaine were given intravenously followed by 2 mg/min infusions for 79.5 +/- 6.5 hours. Electrophysiologic studies all started more than 5 half-lives or 7.5 hours after discontinuation of intravenous lidocaine. Local anesthesia with subcutaneous lidocaine (mean 162 +/- 96 mg) was administered in six patients. Plasma concentrations of lidocaine and its metabolites were determined at the termination of the infusion, 2 and 4 hours afterwards, at the start of the electrophysiologic study prior to local anesthesia, and at the end of the study. Levels were also determined at 12 and 24 hours after discontinuation of the infusion. Mean plasma concentrations of lidocaine, MEGX, and GX at the start of the study were 1.02, 0.86, and 0.62 micrograms/ml, respectively. These had increased to 2.78, 0.92, and 0.68 by the end of the electrophysiologic study. One patient with coronary artery disease and prior out-of-hospital ventricular fibrillation had a therapeutic lidocaine level and no inducible arrhythmia at the time of the initial study. At a subsequent electrophysiologic study, no lidocaine or metabolites were detected in the serum and ventricular fibrillation was induced. Thus using the reported half-life of 90 minutes and discontinuing lidocaine 5 half-lives prior to electrophysiologic evaluation does not ensure lack of electrophysiologic effects of the parent compound or its metabolites. Lidocaine given for local anesthesia further increases lidocaine and metabolite levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Surgical therapy for drug-refractory ventricular tachycardia: results with mapping-guided subendocardial resection.

Surgical therapy with mapping-guided subendocardial resection was used in 30 patients with drug-refractory ventricular tachycardia. Results of preoperative, intraoperative and postoperative electrophysiologic evaluation and long-term clinical follow-up are reported. Left ventricular aneurysm was located in the inferior wall in 8 patients and in the anterior wall in 22. Left ventricular mapping was performed in 15 patients preoperatively and in all 30 patients intraoperatively. Subendocardial resection was supplemented with cryoablation in 26 patients and with laser photocoagulation in 4. Coronary bypass surgery was performed in 27 patients. The surgical mortality rate was 10%; the three deaths were due to cardiogenic shock, pneumonia and sepsis, respectively. At postoperative electrophysiologic study, ventricular tachycardia was inducible in 8 (30%) of 27 patients. Previously ineffective antiarrhythmic drugs were effective in preventing the induction of ventricular tachycardia in four of these eight patients. Two of the remaining four patients received an automatic implantable cardioverterdefibrillator; the other two were treated with amiodarone. At a mean follow-up period of 18 +/- 17 months (range 1 to 52), there has been one sudden death and one nonfatal recurrence of ventricular tachycardia in the 18 patients without inducible arrhythmias postoperatively. Among the eight patients with inducible ventricular tachycardia after subendocardial resection, there has been one nonfatal ventricular tachycardia recurrence. Thus, among the 27 patients surviving surgery, 17 (63%) were cured with surgery alone, and another 7 (26%) had their ventricular tachycardia controlled with drugs (n = 5) or the defibrillator (n = 2). Inability to completely map the tachycardia, a clinical history of cardiac arrest requiring resuscitation and the presence of myocardial infarction within 2 months predicted postoperative arrhythmia inducibility and recurrence.

Adult↗
PubMed1989

Prophylactic automatic implantable cardioverter-defibrillator patches in patients at high risk for postoperative ventricular tachyarrhythmias.

The strategy of placing prophylactic patches for the automatic implantable cardioverter-defibrillator (AICD) without the AICD was employed in 34 patients with coronary artery disease at risk for postoperative ventricular tachycardia undergoing coronary bypass graft surgery (12 patients) or subendocardial resection (22 patients). Patients were selected on the basis of the presence of preoperative sustained ventricular tachycardia (25 patients) or ventricular fibrillation (9 patients) and absence of control of the arrhythmia with 3.6 +/- 1.3 antiarrhythmic drugs by programmed stimulation. Patients having subendocardial resection were also selected on the basis of multiple configurations of ventricular tachycardia, inability to map the tachycardia or posterior wall aneurysm. The surgical mortality rate was 12%, with two deaths after coronary bypass graft surgery and two deaths after subendocardial resection. The AICD patches were removed in 1 of the 34 patients a few hours after surgery because of left atrial laceration and bleeding. Among 10 patients surviving coronary bypass surgery alone, ventricular arrhythmia was not inducible in 6 and in 4 it remained inducible postoperatively. One of the four patients with inducible arrhythmia had the AICD implanted with use of local anesthesia; the other three were treated with drugs. Among 20 patients surviving subendocardial resection, ventricular arrhythmia was noninducible in 15 and remained inducible in 5. Three of these five patients had an AICD implanted; the other two were treated with drugs. At 12 +/- 7 month follow-up, there were no late deaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Sensitivity and specificity of programmed atrial stimulation for induction of supraventricular tachycardias.

The sensitivity and specificity of two programmed atrial stimulation protocols were studied in 92 consecutive patients undergoing electrophysiologic studies both with (35 patients) and without (57 patients) clinical supraventricular arrhythmias. Protocol I (P I) consisted of incremental atrial pacing to 2:1 atrioventricular (AV) block and a single atrial extrastimulus scanned by 10 ms decrements through diastole to the atrial effective refractory period at a single drive-cycle length. Protocol II (P II) included a second atrial extrastimulus scanned by 10 ms decrements through diastole at a single drive-cycle length with the first extrastimulus set 20 ms from the atrial effective refractory period. Rapid atrial pacing at cycle lengths of 350, 300, and 250 ms was then performed with P II. P I was employed in all patients while P II was studied in the final 48 patients only. Of the 35 patients with clinical atrial arrhythmias, 26 (74%) of their arrhythmias were induced with either P I (18/35; sensitivity = 51%) and/or P II (12/17; sensitivity = 71%). Of the 57 patients without clinical atrial arrhythmias (control group), atrial arrhythmias were induced in 11 (19%), 3 with P I (specificity 95%, 54/57) and 8 with P II (specificity 74%, 23/31). The sensitivity of P II was higher (71%), but its specificity was lower (74%) than P I (51% and 95%, respectively; p less than 0.05). The positive predictive value of P II was lower (60%) than that of P I (86%) (p less than 0.05), but the negative predictive value (82%) and predictive accuracy (73%) were comparable to those of P I (76% and 78%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Necropsy study of right atrial appendage: morphology and quantitative measurements.

The right atrial appendage (RAA) of 23 randomly selected autopsied patients was examined at necropsy, and data related to orifice size and appendicular depth measurements and features of the endocardial surface were recorded. The study included 21 men and 2 women aged 71 +/- 15 years (range, 32-91); underlying coronary artery disease was present in 16 patients. The orifice size of the RAA measured 2.0 +/- 1.0 cm (range, 0-5 cm). The orifice size was slightly, but not significantly, smaller in patients over age 70 years compared with those younger than 70. In hearts weighing more than 450 g, the orifice was significantly larger (2.6 cm) than in hearts weighing less (1.4 cm). The appendicular depth averaged 1.2 +/- 0.7 cm (range, 0-2.5 cm), and a significant difference was noted in patients older and younger than 70 years (depth of 0.9 cm vs. 1.5 cm; p less than 0.05). The RAA depth was 0.5 cm or less in 8 patients (35%), 6 of whom represented patients older than 70 years. Antemortem mural thrombi within the RAA were found in three hearts and completely filled the lumen in one. The suitability of the RAA as a site for atrial pacing and secure electrode implantation, particularly when anatomical deficiencies are identified, was also considered. Atrial lead displacement, a relatively common postoperative complication, may be related more to implantation within a shallow appendicular fossa and/or one with larger orifice than to faulty technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗