Acute management of atrial fibrillation and atrial flutter in the critical care unit: should it be ibutilide?

BACKGROUND: Ibutilide is currently indicated for the rapid conversion of atrial fibrillation (Afb) or atrial flutter (Afl) of recent onset but limited to patients who are hemodynamically stable and without symptomatic cardiovascular conditions. HYPOTHESIS: The study was undertaken to assess the efficacy and safety of ibutilide in patients with Afb or Afl associated with acute cardiovascular-medical disorders and in patients receiving prior selective antiarrhythmic drug therapy. METHODS: The study included 34 patients, mean age 75 +/- 16.3 years, with Afb (n = 25) or Afl (n = 9) having a variety of disorders, for example, congestive heart failure, unstable angina, borderline hypotension, respiratory failure, and chronic renal failure. Prior antiarrhythmic drugs consisted of propafenone (n = 5) or amiodarone (n = 3). Eligibility for cardioversion was established with appropriate anticoagulation or transesophageal echocardiography findings. Ibutilide was given as up to two 10 min infusions of 1 mg separated by 10 min. RESULTS: The overall conversion rate after ibutilide was 79.4% (27/34 patients): 80% for Afb and 78% for Afl. More than 90% converted within 1 h of treatment. A high conversion rate of 92% resulted in those with an arrhythmia duration of < or = 1 week. All eight patients with prior antiarrhythmic therapy converted to sinus rhythm. The average baseline QTc interval for all patients increased 17.1% (397 +/- 63.3 to 465 +/- 60.2 ms) at 30 min. For eight patients (including four who received prior antiarrhythmic drugs), QTc interval prolongation > or = 500 ms was associated with nearly half the entire incidence of arrhythmic events. Proarrhythmia, the exclusive adverse effect, consisted of ventricular extrasystoles (n = 10) and nonsustained monomorphic ventricular tachycardia (VT) (n = 2) managed with intravenous MgSO4, and sustained polymorphic VT (n = 1) requiring electrical cardioversion. CONCLUSION: Ibutilide is an effective and well tolerated drug for the rapid termination of Afb or Afl of recent onset associated with symptomatic and/or hemodynamically unstable disorders, and it is most efficacious (> or = 90%) when the atrial arrhythmia is < or = 1 week in duration. Proarrhythmic events are readily manageable in a monitored unit with access to appropriate treatment.

Ibutilide for termination of atrial fibrillation in the Wolff-Parkinson-White syndrome.

Ibutilide promptly restored sinus rhythm on two occasions in an elderly patient with AF and rapid ventricular response associated with the WPW syndrome. As a selective Class III antiarrhythmic agent that prolongs cardiac refractoriness, ibutilide offers an alternative effective therapy for rapid termination of AF in WPW.

Acute myocardial infarction associated with anabolic steroids in a young HIV-infected patient.

The use and abuse of anabolic-androgenic steroids have increased over the past decade and pose a medical and public health problem. In addition to their use by athletes to increase muscle mass and improve performance, people with wasting and malignant diseases are finding that the agents improve both their physical appearance and strength. Unfortunately, anabolic steroids are associated with a number of adverse effects, not the least of which is acute myocardial infarction, which occurred in a 39-year-old man with human immunodeficiency virus infection. It is important for clinicians to be aware of the association and to counsel patients carefully about this and other untoward effects that may occur with the agents.

Role of dopamine in congestive heart failure: a contemporary appraisal.

The pharmacodynamic effects of dopamine, an endogenous catecholamine, are complex and mediated through selective activation of specific dopaminergic and adrenergic receptors in a dose dependent manner. Low dose dopamine (0.5-2 micro g/kg/min) induces intrarenal vasodilatation, augmented renal blood flow, and inhibition of renal tubular sodium reabsorption through direct stimulation of peripheral dopaminergic receptors DA1 and DA2. Intermediate doses (3-10 micro g/kg/min) favor beta(1)-adrenergic receptor stimulation of the heart and peripheral vasoconstriction due to alpha-adrenergic receptor stimulation. At higher does (>10 micro g/kg/min), an elevated systemic vascular resistance prevails and the salutary effect on renal blood flow is diminished or lost. Dopamine is no longer favored as a first line agent for use in congestive heart failure (CHF) owing to the superior pharmacodynamic properties of dobutamine and is more properly used as an agent for vasopressor therapy. Studies have not supported the renal sparing effect of low dose dopamine for critically ill patients with incipient or established acute renal failure due to ischemia or nephrotoxicity. Evidence that low dose dopamine protects renal function during vigorous diuresis for CHF associated with renal insufficiency has clinical support and a rationale for its use. (c)1999 by CHF, Inc.

Echocardiographic observations during in hospital cardiopulmonary resuscitation.

OBJECTIVE: To assess echocardiographic observations during in hospital cardiopulmonary resuscitation (CPR) and the utility of this information in the management of cardiac arrest. DESIGN: Echocardiographic system brought to the hospital site of cardiac arrest and applied to patients in conjunction with conventional CPR. SETTING: Large community-hospital with portable echocardiographic system and an alerted cardiology team skilled in this technique. MEASUREMENTS AND MAIN RESULTS: Mechanical asystole was initially observed in 18 (90%) of 20 cardiac arrest patients during CPR, including four patients with severe bradyarrhythmia as the arrest rhythm. The return of ventricular contractions in four of these 18 patients a short time after starting CPR prompted positive inotropic therapy. Ventricular wall motion was noted in two patients with severe bradyarrhythmia (pseudo-electromechanical dissociation) and the causes of cardiac arrest identified as massive pulmonary embolism and hypovolemia, respectively. A gel-like, coalescent echo contrast within the cardiac chambers was observed 20 to 30 mins after CPR in ten patients with unrelenting cardiac arrest and uniformly associated with an adverse outcome. Six patients survived resuscitation but only two patients survived to hospital discharge. CONCLUSIONS: An echocardiographic examination is feasible during CPR and may offer useful information in the management of the individual patients with cardiac arrest. It may depict the proximate cause of cardiac arrest, e.g., pulmonary embolism, cardiac tamponade, or hypovolemia, and signal the return of ventricular contractions in patients with initially absent mechanical activity. The appearance of intracardiac coalescent echo contrast in our patients with unrelenting cardiac arrest was associated with a failed outcome. The role of echocardiographic imaging in the setting of advanced cardiac life support requires further study.

The benefit of low-dose dopamine during vigorous diuresis for congestive heart failure associated with renal insufficiency: does it protect renal function?

BACKGROUND: Low-dose dopamine, a renal vasodilator, has been used empirically to improve renal function or outcome in critically ill patients with oliguria or acute renal failure. HYPOTHESIS: This study was designed to investigate the efficacy of low-dose dopamine (2 micrograms/kg/min) as a renal-protective agent during vigorous diuresis for congestive heart failure (CHF) associated with mild or moderate renal insufficiency. METHODS: Of 20 study patients (mean age 74.3 +/- 15 years) with severe CHF, 10 (Group A) were randomized to a treatment strategy of intravenous bumetanide (1 mg b.i.d.) alone and another 10 (Group B) to low-dose dopamine and a similar diuretic regimen for a duration of 5 days or less if clinical edema remitted. RESULTS: Group B patients showed a significant improvement in renal function and urinary output: serum blood urea nitrogen 48.9 +/- 10.3 to 32.1 +/- 14.4 mg/dl (p < 0.05); serum creatinine 1.97 +/- 0.24 to 1.49 +/- 0.39 mg/dl (p < 0.05); creatinine clearance 35.6 +/- 11.6 to 48.8 +/- 12.3 ml/min (p < 0.05); and indexed urinary output 0.56 +/- 0.16 to 2.02 +/- 0.72 ml/kg/h (p < 0.05). Group A patients showed a significant increase in urinary output but nonsignificant renal functional deterioration. CONCLUSION: The renal-protective effect of low-dose dopamine in the setting of CHF and vigorous diuresis is supported by this study.

Short-term intravenous milrinone for severe congestive heart failure: the good, bad, and not so good.

We evaluated the overall hemodynamic and clinical effects, beneficial and deleterious, of short-term intravenous milrinone in the management of severe congestive heart failure (CHF). Numerous hemodynamic measurements were obtained in 24 patients (mean age 65 yrs) with advanced, severe CHF (New York Heart Association class IV, ejection fraction 24 +/- 5%), including 3 with concomitant clinical sepsis. Hemodynamic data were recorded at baseline and after a bolus of intravenous milrinone 50 micrograms/kg and maintenance infusion based on creatinine clearance at 0.5, 3, 24 and 48 hours. Cardiac index increased and pulmonary capillary wedge pressure decreased significantly (p < 0.001; 2.07 +/- 0.36 to L/min/m2 and 20.6 +/- 4.0 to 13.5 +/- 2.8 mm Hg, respectively) in 24 patients 0.5 hour after initiation of therapy. These favorable hemodynamic responses, including significant decreases in systemic vascular resistance index and right atrial pressure, were sustained throughout the 48-hour study in 19 patients (79%). Severe hypotension occurred in three patients with superimposed sepsis as the result of exaggerated vasodilatation. One patient had recurrent ventricular tachycardia and another tolerance to milrinone. In two patients, excessive decline in preload and fall in cardiac index were reversed with volume expansion. Intravenous milrinone offered significant short-term hemodynamic benefits in most patients with severe CHF.

Septic cardiomyopathy as a cause of long QT syndrome.

A 63-year-old woman admitted with 2:1 infranodal atrioventricular block subsequently developed ventricular dysfunction incident to septic syndrome. Concomitant changes included an abnormally prolonged QTc interval (600 ms) and the occurrence of torsade de pointes. Restoration of a normal QTc interval and cessation of torsade de pointes was coincident with return of normal ventricular function and remission of sepsis. This report supports the view that sepsis-induced cardiomyopathy is another cause of the long QT syndrome.

Rapid reversal of digitalis delirium using digoxin immune Fab therapy.

A fulminant psychiatric disturbance, as the sole noncardiac manifestation of digitalis toxicity, emerged in a 85-year-old woman during treatment for congestive heart failure. Described more than a century ago as "digitalis delirium," the disorder is characterized by severe agitation, delusional thinking, assaultive behavior, and even death. Digoxin immune Fab therapy was begun because of the fulminant psychiatric manifestations of this toxic state and the clear danger of self-inflicted physical harm. Within 3 h of therapy, a complete and spectacular resolution of all mental symptoms was observed.

Atrial sensing performance of the single-lead VDD pacemaker during exercise.

OBJECTIVES: The purpose of this study was to examine the atrial sensing performance of the single-lead VDD pacing system during exercise and concomitant changes in the amplitude of the atrial electrogram. BACKGROUND: Studies of conventional dual-chamber pacing have demonstrated an overall reduction in the atrial signal amplitude and a variable incidence of atrial undersensing during vigorous exercise. METHODS: The telemetered atrial electrogram and simultaneous surface electrocardiogram (ECG) were continuously recorded in 12 patients (mean age 70.8 years) with an implanted single-lead VDD pacing system during treadmill stress testing. The atrial signal amplitude was measured at peak exercise, and the patients were monitored for maintained atrial synchronized ventricular pacing during the entire exercise and recovery period. RESULTS: The atrial electrographic voltage decreased an average of 19.5% (p < 0.05) during peak exercise, and the reduced P wave amplitude ranged from 6.9% to 59.4% of the preexercise values in 8 of 12 patients. Three patients showed a modest increase in atrial signal amplitude, and one patient had no change. The telemetered electrogram displayed persistent and intact atrial synchronous ventricular pacing throughout the study period. CONCLUSIONS: Despite relatively low atrial signal amplitudes at rest and further decreases during exercise, the single-lead VDD pacemaker maintains reliable atrial tracking and ventricular pacing during vigorous exercise.

Aminophylline induced atrial fibrillation.

Atrial fibrillation (AF) with a rapid ventricular response was induced by intravenous (i.v.) aminophylline during treatment for symptomatic pulmonary disease in three patients who had no evidence of underlying heart disease or previous cardiac arrhythmia. Serum theophylline concentration was therapeutic in two patients and toxic in the third. Previous reports of AF related to aminophylline have underscored its association with toxic serum theophylline concentration. Conversion to sinus rhythm occurred at a time interval (9-14 hours) appropriate to the serum decay of aminophylline, after its cessation. A shortened atrial refractory period and dispersed recovery of excitability consequent to aminophylline may engender multiple reentrant circuits and lead to AF. i.v. diltiazem was more effective than digoxin in the ventricular rate control of AF prior to conversion to sinus rhythm.

Hemodynamic response to intravenous enalaprilat in patients with severe congestive heart failure and mitral regurgitation.

The hemodynamic response 1 hour after 1.25 mg of intravenous (IV) enalaprilat was examined in 20 patients (mean age 75 years) with severe congestive heart failure (CHF) and mitral regurgitation (MR), secondary to ischemic heart disease (NYHA Class IV). Patients were classified into two groups based upon the magnitude of MR as derived from Doppler color flow imaging: Group I (n = 13) had severe MR and Group II (n = 7) had moderate MR. Acute therapy significantly reduced systemic vascular resistance index in both groups and provided effective afterload reduction. Although cardiac and stroke volume indices increased in both groups, an improved forward flow was significant only for Group I (cardiac index 2.2 +/- 0.5 to 2.7 +/- 0.5 l/min/m2, p < 0.02). The magnitude of MR, acutely reduced in all patients, was similarly significant only for Group I (56 +/- 10% to 31 +/- 12%, p < 0.01). The reduction of both pulmonary capillary wedge pressure and mean arterial pressure was significant for both groups. This study supports the use of IV enalaprilat, a parenteral angiotensin-converting enzyme (ACE) inhibitor, as an effective and rapidly acting vasodilator in the management of selected patients with chronic heart failure and MR who require immediate hemodynamic improvement.

Multifocal atrial arrhythmia--a frequent misdiagnosis? A correlative study using the computerized ECG.

All computerized ECGs taken over a 17-week study period were reviewed for the detection of multifocal atrial arrhythmia (MAA)--tachycardia or rhythm--and correlated with the diagnostic statement of the ECG computer system. MAA was identified by the authors in 96 of 11,610 (0.8%) computerized ECGs. In all instances, this specific arrhythmia was misclassified by the computer system as atrial fibrillation. Moreover, during the over-read, only 27.1% of ECGs were correctly diagnosed by the assigned electrocardiographers blinded to this study. MAA is not an uncommon atrial arrhythmia since it was identified in 14% of computerized ECGs interpreted as atrial fibrillation. This study supports the inference that MAA is indeed frequently misdiagnosed by most physicians and the need for improved ECG computer analysis programs for reliable detection of MAA.

Bradyarrhythmias incident to thrombolysis for acute inferior wall infarction. A caveat.

Of ten consecutive patients (eight men, two women; mean age, 59 years) seen over a ten-month period with acute inferoposterior infarction treated with thrombolytic therapy, seven patients demonstrated significant rhythm disturbances at a time interval consistent with clot lysis and in a setting of other clinical markers predictive of reperfusion. One patient had a ventricular arrhythmia treated with intravenous procainamide, but six patients had marked bradyarrhythmias (sinus bradycardia, four patients; and 2 degrees atrioventricular block, one patient) associated with hemodynamic compromise. Urgent treatment consisting of intravenous atropine sulfate (1 mg) briskly restored sinus rhythm and normal arterial pressure within 1 min. Bradyarrhythmias incident to thrombolysis for acute inferoposterior infarction appear to arise as a vagally mediated cardiovascular reflex (Bezold-Jarisch) and the rapid vagolytic effect of intravenous atropine sulfate makes this therapy specific and appropriate.

The RSR' complex not related to right bundle branch block: diagnostic value as a sign of myocardial infarction scar.

An abnormal electrocardiographic (ECG) wave pattern--the RSR' complex--associated with a wide QRS (greater than or equal to 110 msec), unrelated to right bundle branch block (RBBB) or left bundle branch block (LBBB) was identified in 26 patients with old myocardial infarction. Patients were assigned to three groups: in group I (n = 13) the RSR' was present in the precordial leads; in group II (n = 9) the RSR' was present in the inferior limb leads; and in group III (n = 4) the RSR' was present in both. For each patient a severe segmental wall motion abnormality (akinetic in 16 and dyskinetic in 10 patients) consistent with myocardial infarction scar tissue was detected using the equilibrium radionuclide angiocardiogram (n = 24) and the two-dimensional echocardiogram (n = 2). The abnormal RSR' complex arises from a terminal conduction delay (dissimilar to either RBBB or LBBB using the vectorcardiogram) of left ventricular (LV) depolarization within impaired tissue surrounding the infarct scar. This study suggests that the RSR' complex, a unique mural conduction defect, although poorly sensitive has specific diagnostic value and reliability as a sign of myocardial infarction scar.

Pulmonary artery sarcoma: another cause of sudden death.

A patient hospitalized for recurrent syncope and dyspnea died suddenly before a definite clinical diagnosis could be established. At autopsy a large sarcomatous mass (undifferentiated type) was found to arise and totally occlude the pulmonary trunk without evidence of distant metastasis.