Gender and cardiac arrhythmias.

The incidence of certain clinical arrhythmias varies between and women. Clinical and experimental observations suggest the existence of true differences in electrophysiologic properties between the sexes. We review these differences, possible mechanisms, clinical implications, and therapeutic considerations in the treatment of various arrhythmias in women.

Neurally mediated syncope.

Neurally mediated syncope is a disorder of the autonomic regulation of postural tone, which results in hypotension, bradycardia, and loss of consciousness. A wide variety of stimuli can trigger this reflex, the most common stimulus being orthostatic stress. Typically, a patient with neurally mediated syncope experiences nausea, lightheadedness, a feeling of warmth, and pallor before abruptly losing consciousness. If the cause of syncope is unclear, a stepwise approach is necessary to arrive at the diagnosis. The diagnosis of neurally mediated syncope can be confirmed by a head-up tilt-table test. Treatment options include behavioral modification and several pharmacologic therapies. For severe recurrent syncope unresponsive to conventional treatment, a pacemaker can be implanted.

Predictors of conversion to sinus rhythm using ibutilide for atrial fibrillation or flutter.

To determine what factors can predict conversion to sinus rhythm, we retrospectively studied 201 consecutive patients who received ibutilide for treatment of atrial fibrillation or flutter. On multivariate analysis, the following factors were significantly associated with conversion: recent onset of arrhythmia, an underlying atrial flutter rhythm, lack of a history of congestive heart failure, and lack of concomitant digoxin therapy.

Cryoablation of incessant ventricular tachycardia: case report and long-term follow-up.

We report the case of a 52-year-old man who had incessant ventricular tachycardia despite treatment with antiarrhythmic agents. Placement of an implantable cardioverter/defibrillator, radiofrequency ablation, and antitachycardia pacing were ineffective. He underwent intraoperative arrhythmia mapping and cryoablation at our institution. Eighteen months later, he remained free of arrhythmia. He was in New York Heart Association functional class II with an ejection fraction of 30%.

Low-energy internal cardioversion of atrial fibrillation after failed external cardioversion: Texas Heart Institute experience and review of the literature.

In patients with atrial fibrillation, low-energy internal cardioversion may be used to restore sinus rhythm after external cardioversion fails. We used this method in 8 consecutive patients with a mean age of 69.5+/-8.3 (SD) years, 7 (87.5%) of whom were successfully treated with a mean 9.1 J (range, 4 to 14 J). No patient had ventricular arrhythmias at the time of cardioversion, or local groin complications afterward. One patient had recurrent atrial fibrillation the morning after cardioversion, and another patient had an embolus to the renal artery 20 days posttreatment. After 1 month, 5 patients were still in sinus rhythm, and 1 patient was lost to follow-up. This study confirms the efficacy of internal cardioversion in this setting and stresses the importance of a standard anticoagulation protocol before and after cardioversion.

Ventricular arrhythmias in congestive heart failure: clinical significance and management.

The benefit of defibrillator therapy has been well established for patients with LV dysfunction (ejection fraction less than 35%), coronary artery disease, NSVT, and inducible and nonsuppressible ventricular tachycardia. Implantable cardioverter-defibrillator therapy is also indicated for all CHF patients in NYHA functional classes I, II, and III who present with aborted sudden cardiac death, or ventricular fibrillation, or hemodynamically unstable ventricular tachycardia--and also in patients with syncope with no documented ventricular tachycardia but with inducible ventricular tachycardia at electrophysiology study. The ongoing MADIT II trial was designed to evaluate the benefit of prophylactic ICD implantation in these patients (ejection fraction less than 30%, coronary artery disease, and NSVT) without prior risk stratification by PES. The CABG Patch trial concluded that prophylactic placement of an ICD during coronary artery bypass grafting in patients with low ejection fraction and abnormal SAECG is not justifiable. Except for the indications described above, ICD implantation has not been proved to be beneficial as primary or secondary therapy. Until more data are available, patients should be encouraged to enroll in the ongoing clinical trials.

Intravenous amiodarone for recurrent sustained hypotensive ventricular tachyarrhythmias. Intravenous Amiodarone Multicenter Trial Group.

OBJECTIVES: We sought to determine the response rate and safety of intravenous amiodarone in patients with ventricular tachyarrhythmias refractory to standard therapies. BACKGROUND: Numerous small retrospective reports suggest a response of refractory ventricular tachyarrhythmias to intravenous amiodarone, yet no controlled prospective trials exist. METHODS: Two hundred seventy-three patients with recurrent hypotensive ventricular tachyarrhythmias refractory to lidocaine, procainamide and bretylium were randomized to receive one of three doses of intravenous amiodarone: 525, 1,050 or 2,100 mg/24 h (mean [+/- SE] dose 743.7 +/- 418.7, 1,175.2 +/- 483.7, 1,921.2 +/- 688.8 mg, respectively) by continuous infusion over 24 h. RESULTS: Of the 273 patients, 110 (40.3% response rate) survived 24 h without another hypotensive ventricular tachyarrhythmic event while being treated with intravenous amiodarone as a single agent (primary end point). A significant difference in the time to first recurrence of ventricular tachyarrhythmia (post hoc analysis) over the first 12 h was observed when the combined 1,050- and 2,100-mg dose groups were compared with the 525-mg dose group (p = 0.046). The number of supplemental (150 mg) infusions of intravenous amiodarone (given for breakthrough destabilizing tachyarrhythmias) during hours 0 to 6 (prespecified secondary end point) was significantly greater in the 525-mg dose group than in the 2,100-mg dose group (1.09 +/- 1.57 vs. 0.51 +/- 0.97, p = 0.0043). However, there was no clear dose-response relation observed in this trial with respect to success rates (primary end point), time to first recurrence of tachyarrhythmia (post hoc analysis) or mortality (secondary end point) over 24 h. CONCLUSIONS: Intravenous amiodarone is a relatively safe therapy for ventricular tachyarrhythmias refractory to other medications.

Unusual electrocardiographic presentation of right ventricular myocardial infarction.

Isolated right ventricular infarction is uncommon, but when it occurs its prompt recognition may alter therapy substantially. Electrocardiographic changes accompanying acute right ventricular infarction are variable and may be difficult to recognize. The case of a 40-year-old man who had right ventricular infarction with unusual electrocardiographic findings is presented. The clinical, hemodynamic, and electrocardiographic findings of right ventricular infarction are discussed.

Use of amiodarone in the postmyocardial infarction patient.

Amiodarone appears to be an effective antiarrhythmic agent for reducing mortality in the postmyocardial infarction patient with ventricular ectopic activity. Such activity has long been recognized to have an adverse effect on prognosis after acute myocardial infarction. When a strong correlation between ectopic activity and left ventricular dysfunction was demonstrated, ventricular ectopic activity was thought to be a consequence of underlying myocardial damage. However, ventricular ectopic activity is now considered to be an independent risk factor for mortality after myocardial infarction. Because of the basic premise that a positive correlation existed between arrhythmia suppression and improved survival, it had been common practice to use antiarrhythmic agents to treat asymptomatic ventricular ectopic activity in the postinfarction patient. After the results of the Cardiac Arrhythmia Suppression Trial (CAST) were released, this practice was largely abandoned. In the post-CAST era, however, amiodarone has appeared to improve survival in patients who have sustained myocardial infarctions. In this report, we briefly review the pharmacology of amiodarone and discuss the results of relevant clinical trials. Large, multicenter trials currently under way may clarify some of the unanswered questions surrounding the use of this promising antiarrhythmic agent in postmyocardial infarction patients.

Myocarditis-associated ventricular fibrillation. An unusual cause of syncope in Wolff-Parkinson-White syndrome.

We report the case of a 60-year-old man with long-standing symptomatic Wolff-Parkinson-White syndrome who presented with recurrent syncope and documented spontaneous ventricular fibrillation. This primary ventricular fibrillation, which was not preceded by atrial fibrillation, was associated with lymphocytic myocarditis and not with Wolff-Parkinson-White syndrome. The patient was treated with radiofrequency ablation of the accessory pathway and a drug regimen of prednisone, amiodarone, and metoprolol. At the 6-month follow-up, he was asymptomatic and had returned to work. To our knowledge, the association of acute lymphocytic myocarditis and Wolff-Parkinson-White syndrome has not been previously reported.

Transesophageal electrocardiography and adenosine in the diagnosis of wide complex tachycardia.

The diagnosis of wide complex tachycardia based on surface electrocardiography can be difficult. Misdiagnosis occurs frequently and is commonly associated with increased morbidity and mortality. We describe a case of wide QRS complex tachycardia in which transesophageal electrocardiography and intravenous adenosine were used to obtain a reliable diagnosis. These are safe and readily available tools for elucidating the mechanism of wide complex tachyarrhythmias in hemodynamically stable patients.

Effect of valve deformity on results and mitral regurgitation after Inoue balloon commissurotomy.

BACKGROUND: The effect of valve deformity and patient age adversely affect the results of percutaneous transvenous mitral commissurotomy (PTMC) with conventional balloons. METHODS AND RESULTS: These factors were characterized after PTMC with the Inoue balloon. The increases in mitral valve area and mitral regurgitation after the procedure were evaluated comparing echocardiographic score of 8 or less versus more than 8, age of less than 60 versus age of 60 years or more, and age of less than 70 versus age of 70 years or more. One hundred sixty-two patients (mean age, 52 +/- 14 years) were studied. For the entire group, mitral valve area increased from 1.0 to 1.8 cm2 (p less than 0.001). Valve area increased from 1.0 +/- 0.3 to 1.8 +/- 0.6 cm2 in patients with echocardiographic score of 8 or less (n = 102) and from 1.0 +/- 0.3 to 1.7 +/- 0.5 cm2 with echocardiographic score of more than 8 (n = 44). Patients less than 60 years old (n = 104) had increases in valve area from 1.0 +/- 0.3 to 1.8 +/- 0.6 cm2 versus 1.0 +/- 0.4 to 1.8 +/- 0.6 cm2 for those 60 years old or older (n = 50) (p = NS). There was no significant difference in resultant valve area when the age division was increased to less than 70 versus 70 years or more. Similarly, the percentage of patients with 2+ or greater increase in mitral regurgitation was not different for those with higher than for those with lower echocardiographic scores (4% versus 12%, p = NS), age of less than 60 versus age of 60 years or more (10% versus 10%, p = NS), or age of less than 70 versus age of 70 or more years (9% versus 18%, p = NS). Valve replacement for mitral regurgitation was performed in four patients (one emergency), all with echocardiographic scores of less than 8. CONCLUSIONS: Age and extent of valve deformity do not have significant effects on acute results of PTMC using the Inoue balloon. Unique balloon geometry or the controlled, stepwise balloon sizing may explain these acceptable acute results in patients with more-deformed valves.

Balloon mitral valvuloplasty: clinical experience at the Texas Heart Institute.

For treatment of symptomatic mitral valve stenosis, balloon valvuloplasty has emerged as an alternative to surgery. This report describes our initial clinical experience with balloon mitral valvuloplasty in 45 patients (37 women and 8 men; age range, 34 to 79 years) treated from December 1986 through March 1991. Thirty-nine of the 45 patients (87%) underwent a complete procedure (that is, they had at least 1 balloon inflation and did not require emergency surgery). Pre- and post-procedural catheterization showed that these patients had a significant improvement in mean mitral valve area, from 1.0 +/- 0.3 cm(2) to 1.9+/-0.8 cm(2). Catheterization data revealed a decrease in transmitral gradient, from 16.3 +/- 7.6 mmHg to 7.6 +/- 3.7 mmHg, and an increase in cardiac index, from 2.5 +/- 0.7 L/min/m(2) to 2.9 +/- 0.8 L/min/m(2). These improvements were all statistically significant (p <0.0005). A clinically successful balloon mitral valvuloplasty was defined as an uncomplicated procedure yielding either a final mitral valve area > 1.5 cm(2) or a 40% increase in mitral valve area, and an immediate post-valvuloplasty mitral regurgitation grade 2+ increase in mitral regurgitation (4 patients). In 6 patients, the procedure was considered incomplete because of technical failure or complications. Two of these patients had nonfatal cardiac tamponade, and 1 had a torn mitral annulus that resulted in severe mitral regurgitation requiring emergent mitral valve replacement. In another patient, we were unable to cross the mitral valve with a 2nd valvuloplasty balloon after the 1st one proved unsatisfactory. There were 2 in-hospital deaths, only 1 of which was related to the procedure. Over time, our success rate has improved from 60% in the 1st 20 patients to 80% in the subsequent 25 patients, reflecting a learning curve. In particular, we attribute this improvement to increased operator experience, refinements in balloon technology, and, in more recent procedures, the initial use of smaller balloons. The improvement also reflects a change in demographic pattern, characterized by recent application of the procedure to younger patients with fewer concomitant illnesses. Because long-term follow-up data are available for only 23 patients, we cannot comment on the long-term efficacy of this technique. Overall, however, our short-term experience indicates that balloon mitral valvuloplasty is a safe, effective alternative for treating symptomatic mitral valve stenosis in carefully selected adults.

Rate-related left bundle branch block as a cause of non-ischemic chest pain.

A case is presented of rate-dependent left bundle branch block associated with chest pain in a patient with angiographically normal coronary arteries. Lactate extraction showed no evidence of myocardial ischemia. It appears that in this case, chest pain was associated with sudden ventricular asynergy rather than myocardial ischemia.

Coronary sinus mapping through a persistent left superior vena cava in Wolff-Parkinson-White syndrome.

Persistent left superior vena cava is not an uncommon finding in patients undergoing evaluation for preexcitation syndromes. In such patients, this anatomical configuration might be used advantageously for mapping and ablation of a left-sided accessory pathway during electrophysiologic studies. We successfully used this mapping approach in a 16-year-old boy undergoing evaluation for Wolff-Parkinson-White syndrome. The patient was found to have a persistent left superior vena cava confluent with the coronary sinus. During electrophysiologic studies, mapping of the left-sided accessory pathway was facilitated by retrograde entry into the coronary sinus through the persistent left superior vena cava. Mapping was also performed in the conventional manner, yielding identical results and thus validating this new technique.

Cryosurgical modification of the atrioventricular node for treatment of atrioventricular junctional reentrant tachycardia.

Surgical correction of atrioventricular nodal reentrant tachycardia with preservation of atrioventricular nodal conduction in a 28-year-old woman is reported. At surgery, electrophysiologic mapping techniques were used during tachycardia to reveal and enable ablation of the appropriate site of atrial activation. Postoperative electrophysiologic studies indicated successful atrioventricular nodal modification.

Balloon aortic valvuloplasty: the Texas Heart Institute experience.

Between October 1986 and January 1989, 73 percutaneous catheter balloon aortic valvuloplasty procedures were performed in 68 adult patients (32 men and 36 women; mean age, 77 +/- 9 years) with severe symptomatic aortic stenosis. Following the procedures, significant improvements were documented in aortic valve area, mean transvalvular pressure gradient, peak-to-peak pressure gradient, left ventricular systolic pressure, radionuclide ejection fraction, and left ventricular end-systolic volume index. There were no procedure-related deaths, but 2 patients (3%) required emergency surgery for acute aortic regurgitation. During hospitalization, 4 patients had persistent symptoms (3 died; 1 subsequently underwent repeat valvuloplasty and later, valve replacement). Short-term clinical improvement was noted in 59 of 65 patients (91%). During the follow-up period (mean, 11.6 +/- 8.4 months), 22 patients died (including the 3 who died during hospitalization). Sixteen underwent aortic valve replacement (including the 2 who underwent emergency aortic valve replacement); all 16 are alive. A total of 6 patients (1 with an initial balloon aortic valvuloplasty at an outside institution) underwent repeat valvuloplasty; of those, 4 subsequently underwent aortic valve replacement, and 2 died. Of the remaining 30 patients, 27 continue to experience relief of symptoms, and 3 have clinical symptoms that have not improved or have worsened since the valvuloplasty procedure. Multivariate predictors of clinical outcome (p<0.05) included post-valvuloplasty aortic valve area, pre- and post-valvuloplasty ejection fraction, absence of coronary artery disease, and absolute change in valve area. Overall actuarial and event-free survivals were 83% and 49%, respectively, at 1 year. Although clinical improvement is frequently noted after balloon aortic valvuloplasty, the procedure is associated with a high recurrence of symptoms and restenosis. Balloon aortic valvuloplasty is at best a palliative procedure; when feasible, surgical valve replacement is the more definitive therapy.