Douglas L. Wood

Left ventricular dysfunction due to atrial fibrillation in patients initially believed to have idiopathic dilated cardiomyopathy.

Ten patients aged 22 to 80 years (median 57) with severe left ventricular (LV) dysfunction and atrial fibrillation (AF) with rapid ventricular response were evaluated after therapy. Because most patients were unaware of their arrhythmia, duration was usually unknown. All patients had heart failure symptoms; 9 presented with New York Heart Association class III or IV disability, and 1 with class II disability. Initial LV ejection fraction ranged from 12 to 30% (median 25). No patient had symptomatic coronary artery disease (4 underwent angiography). Myocarditis and infiltrative processes were excluded by biopsy in 5 patients. All patients were considered initially to have idiopathic dilated cardiomyopathy with secondary AF. Ventricular rate was controlled in all patients, with sinus rhythm restored in 5. At follow-up (median 30 months, range 3 to 56), all patients were asymptomatic. LV ejection fraction after treatment ranged from 40 to 64% (median 52). It is concluded that in some patients initially considered to have idiopathic dilated cardiomyopathy, AF with rapid ventricular response may be the primary cause rather than the consequence of severe LV dysfunction. LV dysfunction may be completely reversible with ventricular rate control.

Echocardiographic Findings in Systemic Amyloidosis: Spectrum of Cardiac Involvement and Relation to Survival

One hundred thirty-two patients with biopsy-proven systemic amyloidosis underwent echocardiographic examination to define the spectrum of cardiac involvement. Echocardiographic abnormalities were then correlated with clinical variables and survival at follow-up. Patients were subgrouped by left ventricular wall thickness: Group I, mean wall thickness 12 mm or less; Group II, mean wall thickness greater than 12 mm but less than 15 mm; Group III, mean wall thickness 15 mm or greater; or Group IV, atypical features such as wall motion abnormalities or left ventricular dilation. Patients with greater wall thickness had a higher frequency of associated echocardiographic abnormalities such as left atrial enlargement or granular sparkling appearance on two-dimensional examination and, more commonly, reduced systolic function. The occurrence of clinical congestive heart failure was strongly correlated with greater wall thickness and multiple other echocardiographic abnormalities. Survival was negatively influenced both by greater wall thickness and reduced systolic function. The median survival of the entire group was 1.1 years. Echocardiographic examination is an important tool for establishing the presence of cardiac amyloid involvement and may be useful in estimating prognosis in such patients.

Adenosine: Potential modulator for vasovagal syncope

OBJECTIVES This study examined the hypothesis that adenosine could provoke a vasovagal response in susceptible patients. Mechanisms of the vasovagal response were further explored by studying the adenosine-mediated reactions. BACKGROUND Increased sympathetic activity is frequently observed before vasovagal syncope. Recent studies have demonstrated that adenosine, in addition to its direct bradycardiac and vasodilatory effects, can increase sympathetic discharge by activating cardiovascular afferent nerves. METHODS The effects of adenosine and head-up tilt-table testing with or without isoproterenol were prospectively evaluated in 85 patients examined for syncope after negative results of electrophysiologic testing (51 men and 34 women, mean [+/- SD] age 61 +/- 17 years). Adenosine bolus injections of 6 mg and 12 mg were sequentially administered to patients in the upright position. The same protocol was implemented in 14 normal control subjects (7 men and 7 women, mean [+/- SD] age 38 +/- 10 years). RESULTS Transient hypertension or tachycardia was observed in 57 (67%) and 20 (24%) patients after administration of 6 mg and 12 mg of adenosine, respectively, during the immediate phase (first 15 s), suggesting direct sympathetic activation. Hypotension and reflex tachycardia were observed in all patients during the delayed phase (15 to 60 s after adenosine injection), suggesting baroreceptor unloading. A vasovagal response was induced in 22 (26%) and 29 (34%) patients after adenosine administration and during tilt-table testing. Inducibility of a vasovagal response by these two methods was comparable (p = 0.12). Of the control subjects, one (7%) had a vasovagal response after adenosine administration and one (7%) had a positive response during tilt-table testing. CONCLUSIONS These observations support the idea that adenosine is an endogenous modulator of the cardiac excitatory afferent nerves. Sympathetic activation by adenosine can be direct (i.e., cardiac excitatory afferent nerves) and indirect (i.e., vasodilation and reflex sympathetic activation). Adenosine could be an important modulator in triggering a vasovagal response in susceptible patients during examination for syncope.

Role of invasive electrophysiologic testing in patients with symptomatic bundle branch block

Electrophysiologic testing was performed in 112 symptomatic patients with bundle branch block. Abnormalities included HV interval 70 ms or longer (35 patients), infra-Hisian block with atrial pacing (6 patients) and sinus node dysfunction (23 patients). Inducible ventricular tachycardia occurred in 47 patients (42%). Therapy was based on the electrophysiologic test result: group I--16 patients with no therapy (normal study results); group II--34 patients with permanent pacing alone; group III--39 patients with antiarrhythmic therapy alone; and group IV--21 patients with both antiarrhythmic therapy and permanent pacing. Cumulative 4-year survival rates were 83% in group I, 84% in group II, 63% in group III and 84% in group IV (mean follow-up 2.5 years). Recurrent syncope occurred in 19% of group I, 6% of group II, 33% of group III and 19% of group IV. In symptomatic patients with bundle branch block and normal electrophysiologic test results, prognosis is good without treatment. In patients undergoing permanent pacing based on electrophysiologic testing, survival is good and rate of symptom recurrence is low. Electrophysiologic testing identifies patients with inducible ventricular tachycardia for whom antiarrhythmic therapy is indicated but who nevertheless have a poor prognosis.

Symptomatic "isolated" carotid sinus hypersensitivity: Natural history and results of treatment with anticholinergic drugs or pacemaker

Because syncope may occur intermittently in patients with carotid sinus hypersensitivity, a knowledge of its natural history is needed as a basis for interpreting the usefulness of therapy. Fifty-six consecutive patients are described (47 men and 9 women; mean age 61 years) with carotid sinus hypersensitivity and syncope in whom 24 hour ambulatory monitoring and intracardiac electrophysiologic study revealed no other cause for the syncope. The mean duration of symptoms was 44 months (range 1 to 480) and the mean number of episodes was 4.0 (range 1 to 20). During a follow-up period of 6 to 120 months (median 40), syncope recurred in 3 of 13 patients who received no treatment, in 2 of 23 patients who received a pacemaker and in 4 of 20 patients who received anticholinergic drugs (incidences corrected for totals available at follow-up: 27, 9 and 22%, respectively). Two-thirds of the patients receiving no treatment were asymptomatic compared with all nine of the patients with syncope and a pure cardioinhibitory response to carotid sinus massage who received an atrioventricular (AV) sequential pacemaker. Although pacing was effective in abolishing syncope, its use should be reserved for recurrent episodes because of the high rate of spontaneous remission of symptoms.

Propafenone for paroxysmal atrial fibrillation

Abstract Propafenone is a class 1C antiarrhythmic agent potentially effective in paroxysmal atrial fibrillation (AF). Propafenones effects upon automaticity and conduction in the atrium should decrease the frequency of AF. In the event of a recurrence of AF, its effects on atrioventricular nodal conduction would tend to slow the ventricular response. 1–3 Previously, we demonstrated that propafenone was safe and effective for treating patients with refractory complex ventricular ectopic activity 4 and paroxysmal supraventricular reentrant tachycardia due to reentry in the atrioventricular node or by an accessory atrioventricular pathway. 3 This study reviews our experience with propafenone in patients with paroxysmal AF who had long-term follow-up for control of their rhythm disturbance.

Increased vagal tone as an isolated finding in patients undergoing electrophysiological testing for recurrent syncope: response to long term anticholinergic agents.

Features suggestive of an isolated increase in vagal tone during electrophysiological study were found in 12 patients with recurrent near syncope or syncope. Results at neurological and cardiac evaluation were otherwise normal. The increased tone or heightened sensitivity to vagal tone was manifested by abnormal atrioventricular nodal refractoriness and conduction that were reversed with atropine. The patients underwent long term treatment with an anticholinergic agent (propantheline bromide) and 75% improved. Before treatment they had experienced a median of seven episodes (range 3-28) of near syncope or syncope during 10.5 months (range 1-60). During treatment these episodes decreased to a median of one (range 0-15) during 22.5 months (range 3-67); six patients experienced no further symptoms. Three patients continued to have syncope while on treatment, and one of these required permanent cardiac pacing. No additional cause for syncope was identified in any patient. During electrophysiological assessment of patients with syncope, evidence may be obtained pointing to an increase in vagal tone. In many of these patients treatment with anticholinergic drugs seemed to improve or eliminate the symptoms.

Amiodarone pulmonary toxicity: report of two cases associated with rapidly progressive fatal adult respiratory distress syndrome after pulmonary angiography.

Use of amiodarone, an investigational antidysrhythmic agent, has been associated with cases of pulmonary toxicity. The mechanism of amiodarone pulmonary toxicity is unknown, and recommendations for the assessment and treatment of patients with this condition continue to evolve. In two patients with clinically diagnosed amiodarone pulmonary toxicity, a rapidly progressive and fatal adult respiratory distress syndrome developed after pulmonary angiography. Physicians should be aware of the potential for serious complications of pulmonary angiography in patients with presumed or clinically diagnosed amiodarone toxicity.

Influence of ventricular function and presence or absence of coronary artery disease on results of electrophysiologic testing for asymptomatic nonsustained ventricular tachycardia.

One hundred ten patients with asymptomatic nonsustained ventricular tachycardia (VT) were evaluated prospectively to assess the value of electrophysiologic testing. This testing consisted of up to 3 extrastimuli delivered during 3 drive cycle lengths from 2 right ventricular sites. A positive study was defined as monomorphic VT lasting 30 seconds or requiring cardioversion. Patients with a positive study were treated, and serial drug testing was done. An event during follow-up was sustained VT or cardiac arrest. The mean follow-up was 15 months. Of 57 patients with an ejection fraction greater than or equal to 40%, 6 had a positive electrophysiologic test with 1 event and 51 had a negative test with 1 event. Twenty-eight patients had an ejection fraction less than 40% and coronary artery disease: 14 had a positive test with 1 event, and 14 had a negative test with 3 events. Twenty-five patients had an ejection fraction less than 40% and no coronary artery disease: 1 had a positive test with no events, and 24 had a negative test with 8 events. Only ejection fraction and congestive heart failure class were found to be independent predictors of outcome. Patients with an ejection fraction greater than 40% had low inducibility (11%), had few events (3.5%) and did not require electrophysiologic testing. In patients with an ejection fraction less than 40% and coronary artery disease, inducibility was high (50%) and a negative study was of no value. Patients with an ejection fraction less than 40% and no coronary artery disease had low inducibility (4%), had frequent events (33%) and did not benefit from electrophysiologic testing.

Surgical treatment of accessory atrioventricular pathways and symptomatic tachycardia in children and young adults

Twenty-seven patients aged 21 years or younger (mean 15) with symptomatic tachycardia underwent operation for ablation of an accessory atrioventricular pathway. Six patients had associated Ebsteins malformation of the tricuspid valve. Supraventricular tachycardia had been present for a mean of 5 years. At electrophysiologic study, 4 patients were found to have 2 accessory pathways. Left ventricular free wall pathways were found in 14 patients, right ventricular free wall pathways in 10 and septal pathways in 6. Successful initial ablation of all the pathways was achieved in 26 of the 27 patients. No patient died perioperatively and none had persistent complete heart block. During a mean follow-up of 11 months, no patient had recurrence of an arrhythmia related to the accessory pathway. Thus, the surgical treatment of children and young adults with accessory atrioventricular pathways and symptomatic supraventricular tachycardia is safe and effective. For these patients, unless the tachycardia can be easily controlled with a minimal number of drugs and adverse effects, surgical ablation should be considered early in the clinical course.