Biomedical subjects
Publications and source records attributed to R Goyal.
Two hundred patients with atrial fibrillation underwent transthoracic cardioversion using adhesive electrodes positioned at the apex and right infraclavicular area, and the apex electrode was randomly selected to serve as the cathode or anode. The mean defibrillation energy requirement with the cathodal configuration was significantly lower than with the anodal configuration.
BACKGROUND: Atrial fibrillation cannot always be converted to sinus rhythm by transthoracic electrical cardioversion. We examined the effect of ibutilide, a class III antiarrhythmic agent, on the energy requirement for atrial defibrillation and assessed the value of this agent in facilitating cardioversion in patients with atrial fibrillation that is resistant to conventional transthoracic cardioversion. METHODS: One hundred patients who had had atrial fibrillation for a mean (+/-SD) of 117+/-201 days were randomly assigned to undergo transthoracic cardioversion with or without pretreatment with 1 mg of ibutilide. We designed a step-up protocol in which shocks at 50, 100, 200, 300, and 360 J were used for transthoracic cardioversion. If transthoracic cardioversion was unsuccessful in a patient who had not received ibutilide pretreatment, ibutilide was administered and transthoracic cardioversion attempted again. RESULTS: Conversion to sinus rhythm occurred in 36 of 50 patients who had not received ibutilide (72 percent) and in all 50 patients who had received ibutilide (100 percent, P<0.001). In all 14 patients in whom transthoracic cardioversion alone failed, sinus rhythm was restored when cardioversion was attempted again after the administration of ibutilide. Pretreatment with ibutilide was associated with a reduction in the mean energy required for defibrillation (166+/-80 J, as compared with 228+/-93 J without pretreatment; P<0.001). Sustained polymorphic ventricular tachycardia occurred in 2 of the 64 patients who received ibutilide (3 percent), both of whom had an ejection fraction of 0.20 or less. The rates of freedom from atrial fibrillation after six months of follow-up were similar in the two randomized groups. CONCLUSIONS: The efficacy of transthoracic cardioversion for converting atrial fibrillation to sinus rhythm was enhanced by pretreatment with ibutilide. However, use of this drug should be avoided in patients with very low ejection fractions.
BACKGROUND: Conversion of chronic atrial fibrillation (AF) is associated with atrial stunning, but the short-term effect of a brief episode of AF on left atrial appendage (LAA) emptying velocity is unknown. The purpose of this study was to determine whether a short episode of AF affects left atrial function and whether verapamil modifies this effect. METHODS AND RESULTS: The subjects of this study were 19 patients without structural heart disease undergoing an electrophysiology procedure. In 13 patients, LAA emptying velocity was measured by transesophageal echocardiography in the setting of pharmacological autonomic blockade before, during, and after a short episode of AF. During sinus rhythm, the baseline LAA emptying velocity was measured 5 times and averaged. AF was then induced by rapid right atrial pacing. After either spontaneous or electrical conversion, LAA emptying velocity was measured immediately on resumption of sinus rhythm and every minute thereafter. The mean duration of AF was 15.3+/-3.8 minutes. The mean baseline emptying velocity was 70+/-20 cm/s. The first post-AF emptying velocity was 63+/-20 cm/s (P=0.02 versus baseline emptying velocity). The post-AF emptying velocity returned to the baseline emptying velocity value after 3.0 minutes. The mean percent reduction in post-AF emptying velocity was 9.7+/-21% (range, 15% increase to 56% decrease). A second group of 6 patients were pretreated with verapamil (0.1-mg/kg IV bolus followed by an infusion of 0.005 mg. kg-1. min-1). In these patients, the first post-AF emptying velocity, 58+/-14 cm/s, was not significantly different from the pre-AF emptying velocity, 60+/-13 cm/s (P=0.08). CONCLUSIONS: In humans, several minutes of AF may be sufficient to induce atrial contractile dysfunction after cardioversion. When atrial contractile dysfunction occurs, there is recovery of AF within several minutes. AF-induced contractile dysfunction is attenuated by verapamil and may be at least partially mediated by cellular calcium overload.
Intestinalized epithelium in traditional long-segment Barrett's esophagus (BE) shows increased proliferative activity, which is postulated to be an early step in the metaplasia-dysplasia-carcinoma sequence. The aim of this study was to evaluate the proliferative activity of intestinalized epithelium of the distal esophagus and gastroesophageal junction (IMEGEJ). Tissue sections from 78 consecutive patients (20 with IMEGEJ, 58 without IMEGEJ) who had elective upper gastrointestinal endoscopy over a 6-month period were immunohistochemically stained with MIB-1, the Ki-67 proliferation-antigen-associated marker, for evaluation of the crypt MIB-1 proliferation index (PI), size of the proliferative zone (PZ), and the presence of surface epithelial staining. Data from the IMEGEJ and non-IMEGEJ groups, and from 15 age-matched patients with traditional long-segment BE (>3.0 cm), were compared statistically. IMEGEJ patients showed a statistically significant increase in the mean crypt PI compared with non-IMEGEJ controls (21.9+/-19.5 v 14.3+/-9.3; P=.01). In addition, IMEGEJ cases showed an increase in the mean crypt PZ (52.3+/-16.4 v 45.2+/-17.2; P=.05), and a trend toward an increase in the percentage of cases with MIB-1-positive surface epithelial cells (50% v 33%, P=.18). Patients with IMEGEJ did not differ from patients without IMEGEJ with respect to any other clinical or histological feature, including signs or symptoms of gastroesophageal reflux disease and presence or absence of esophagitis or carditis. The MIB-1 results of the patients with long-segment BE (MIB-1 PI = 22.6+/-20.5, MIB-1 PZ = 51.8+/-19.6, proportion of cases with MIB-1-positive surface cells = 66%) were similar to those with IMEGEJ. Intestinalized epithelium in the distal esophagus or gastroesophageal junction shows increased proliferative activity in comparison with patients without intestinalized epithelium. This finding supports an increased risk of carcinogenesis in patients with IMEGEJ.
A case of sezary syndrome where the sezary cells showed cytoplasmic hairy projections is reported. The patient had typical exfoliative erythematous dermatitis, high white cell count, atypical lymphocytes of T-phenotype with folded nuclei and bone marrow involvement. The ultra structure study showed cerebriform nucleus and cytoplasmic projections.
Rates of proliferation and apoptosis as well as expression of tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta) and the number of macrophages were measured in bone marrow (BM) biopsies of 33 patients who presented with hypocellular (cellularity < 30%) myelodysplastic syndromes (MDS). Results showed that 2/3 of the patients had high apoptosis, high cytokine levels and large number of macrophages in their biopsies while 1/3 did not. Apoptosis and TNF-alpha levels were directly related (r = 0.583, P = 0.003, n = 24) as was apoptosis and the degree of anemia (P = 0.033, n = 18). A subgroup of patients with abnormalities of chromosomes 5 or 7 had higher platelets (P = 0.026) and higher apoptosis (P = 0.038) when compared with the rest of the group. Eight patients had no evidence of apoptosis and almost no detectable TNF-alpha in their biopsies. We conclude that within the hypocellular variant of MDS, there may be two distinct sub-groups of patients, one who present with high cytokine-mediated intramedullary apoptosis and the other who may be better characterized as having a stem-cell failure defect since they showed no evidence of apoptosis.
OBJECTIVE: The purpose of this study was to determine if the atrial response upon cessation of ventricular pacing associated with 1:1 ventriculoatrial conduction during paroxysmal supraventricular tachycardia is a useful diagnostic maneuver in the electrophysiology laboratory. BACKGROUND: Despite various maneuvers, it can be difficult to differentiate atrial tachycardia from other forms of paroxysmal supraventricular tachycardia. METHODS: The response upon cessation of ventricular pacing associated with 1:1 ventriculoatrial conduction was studied during four types of tachycardia: 1) atrioventricular nodal reentry (n = 102), 2) orthodromic reciprocating tachycardia (n = 43), 3) atrial tachycardia (n = 19) and 4) atrial tachycardia simulated by demand atrial pacing in patients with inducible atrioventricular nodal reentry or orthodromic reciprocating tachycardia (n = 32). The electrogram sequence upon cessation of ventricular pacing was, categorized as "atrial-ventricular" (A-V) or "atrial-atrial-ventricular" (A-A-V). RESULTS: The A-V response was observed in all cases of atrioventricular nodal reentrant and orthodromic reciprocating tachycardia. In contrast, the A-A-V response was observed in all cases of atrial tachycardia and simulated atrial tachycardia, even in the presence of dual atrioventricular nodal pathways or a concealed accessory atrioventricular pathway. CONCLUSIONS: In conclusion, an A-A-V response upon cessation of ventricular pacing associated with 1:1 ventriculoatrial conduction is highly sensitive and specific for the identification of atrial tachycardia in the electrophysiology laboratory.
OBJECTIVES: The purpose of this study was to determine the outcome of patients with nonischemic dilated cardiomyopathy, unexplained syncope and a negative electrophysiology test who are treated with an implantable defibrillator. BACKGROUND: Patients with nonischemic cardiomyopathy and unexplained syncope may be at high risk for sudden cardiac death, and they are sometimes treated with an implantable defibrillator. METHODS: This study prospectively determined the outcome of 14 consecutive patients who had a nonischemic cardiomyopathy, unexplained syncope and a negative electrophysiology test and who underwent defibrillator implantation (Syncope Group). Nineteen consecutive patients with a nonischemic cardiomyopathy and a cardiac arrest who were treated with a defibrillator (Arrest Group) served as a control group. RESULTS: Seven of 14 patients (50%) in the Syncope Group received appropriate shocks for ventricular arrhythmias during a mean follow-up of 24+/-13 months, compared with 8 of 19 patients (42%) in the Arrest Group during a mean follow-up of 45+/-40 months (p = 0.1). The mean duration from device implantation until the first appropriate shock was 32+/-7 months (95% confidence interval [CI], 18 to 45 months) in the Syncope Group compared to 72+/-12 months (95% CI, 48 to 96 months) in the Arrest Group (p = 0.1). Among patients who received appropriate shocks, the mean time from defibrillator implantation to the first appropriate shock was 10+/-14 months in the Syncope Group, compared with 48+/-47 months in the Arrest Group (p = 0.06). Recurrent syncope was always associated with ventricular tachyarrhythmias. CONCLUSIONS: The high incidence of appropriate defibrillator shocks and the association of recurrent syncope with ventricular arrhythmias support the treatment of patients with nonischemic cardiomyopathy, unexplained syncope and a negative electrophysiology test with an implantable defibrillator.
INTRODUCTION: The relationship between temperature at the electrode-tissue interface and the loss of AV and ventriculoatrial (VA) conduction is not established, and the optimal target temperature for the slow pathway approach to radiofrequency ablation of AV nodal reentrant tachycardia (AVNRT) is unknown. Therefore, the purpose of this study was to compare target temperatures of 48 degrees C and 60 degrees C during the slow pathway approach to ablation of AVNRT. METHODS AND RESULTS: The study included 138 patients undergoing ablation for AVNRT. Patients undergoing slow pathway ablation using closed-loop temperature monitoring were randomly assigned to a target temperature of either 48 degrees C or 60 degrees C. The primary success rates were 76% in the patients assigned to 48 degrees C and 100% in the patients assigned to 60 degrees C (P < 0.01). The ablation procedure duration (33 +/- 31 min vs 26 +/- 28 min; P = 0.2), fluoroscopic time (25 +/- 15 min vs 24 +/- 16 min; P = 0.5), and mean number of applications (9.3 +/- 6.5 vs 7.8 +/- 8.1; P = 0.3) were similar in patients assigned to 48 degrees and 60 degrees C, respectively. The mean temperature (46.1 degrees +/- 24.8 degrees C vs 48.7 +/- 3.2 degrees C; P < 0.01), the temperature associated with junctional ectopy (48.1 degrees +/- 2.0 degrees C vs 53.5 degrees +/- 3.5 degrees C, P < 0.0001), and the frequency of VA block during junctional ectopy (24.6% vs 37.2%; P < 0.0001) were less in the patients assigned to 48 degrees C compared to 60 degrees C. The frequency of transient or permanent AV block was similar in each group (2.8% vs 3.6%; P = 0.2). In the 60 degrees C group, only 12% of applications achieved an electrode temperature of 60 degrees C. During follow-up of 9.9 +/- 4.2 months, there was one recurrence of AVNRT in the 48 degrees C group and none in the 60 degrees C group. CONCLUSIONS: Compared to 48 degrees C, a target temperature of 60 degrees C during radiofrequency slow pathway ablation is associated with a higher primary success rate and a higher incidence of VA block during junctional ectopy induced by the radiofrequency energy. AV block is not more common with the higher target temperature, but only if VA conduction is aggressively monitored during applications of radiofrequency energy.
INTRODUCTION: The postpacing interval (PPI) has been used to discriminate bystander sites from critical sites within a ventricular tachycardia (VT) reentry circuit, with a PPI that is similar to the VT cycle length (CL) being indicative of a site within the reentry circuit. The purpose of this study was to assess the clinical value of the PPI for identifying effective target sites for ablation of VT at sites of concealed entrainment in patients with prior myocardial infarction. METHODS AND RESULTS: In 24 patients with coronary artery disease and a past history of myocardial infarction, 36 VTs with a mean CL of 483+/-80 msec (+/- SD) were mapped and targeted for radiofrequency (RF) ablation. The only criterion used to select target sites for ablation was concealed entrainment. In a post hoc analysis, the PPI was measured at 47 ineffective and 26 effective ablation sites. The mean PPI-VTCL difference at the 26 effective sites (114+/-137 msec) did not differ significantly from the mean at the 47 ineffective sites (177+/-161 msec; P = 0.1). The sensitivity of a PPI-VTCL difference < or = 30 msec for identifying an effective ablation site was 46%, the specificity 64%, the positive predictive value 41%, and the negative predictive value 68%. CONCLUSION: The PPI-VTCL difference is not useful for discriminating between sites of concealed entrainment that are within or outside of a VT reentry circuit in patients with prior infarction. Therefore, in patients with prior infarction, the PPI is not clinically useful for identifying sites of concealed entrainment at which RF ablation should or should not be attempted.
INTRODUCTION: Isolated diastolic potentials have been found to be helpful in identifying critical sites for ablation of ventricular tachycardia (VT) in patients with coronary artery disease. However, discrete potentials that occur during systole have not been previously described. The purpose of this study was to determine the significance of discrete systolic potentials during VT in patients with coronary artery disease. METHODS AND RESULTS: Twenty-seven patients with a mean age of 66 +/- 12 years ( +/- standard deviation) who had coronary artery disease underwent radiofrequency catheter ablation of 42 VTs that had a mean cycle length of 486 +/- 78 msec. The only criterion used to select target sites for ablation was concealed entrainment, which was present at 92 sites. Thirty-five of the 42 VTs (83%) were successfully ablated. A discrete systolic potential was recorded during 7 of the 42 VTs (17%). In all cases, the interval between the discrete systolic potential and the next QRS complex was equal to the stimulus-QRS interval during concealed entrainment. At all seven sites where a discrete systolic potential was recorded, delivery of radiofrequency energy resulted in successful ablation of the VT. CONCLUSION: Discrete systolic potentials may be present in patients with coronary artery disease in approximately 17% of VTs in which there is concealed entrainment. If the interval between the discrete systolic potential and the next QRS complex matches the stimulus-QRS interval during concealed entrainment, delivery of radiofrequency energy is likely to result in successful ablation of the VT.
BACKGROUND: The relationship between postdefibrillation ventricular arrhythmias and shock strength is poorly understood in patients with implantable defibrillators. The purpose of this study was to characterize the relationship between postdefibrillation ventricular arrhythmias and shock strength. METHODS AND RESULTS: Forty-three patients with an implanted defibrillator underwent six separate inductions of ventricular fibrillation (VF) after a step-down defibrillation energy requirement (7.3 +/- 4.6 J) was determined. For each of the first three inductions of VF, the first two shocks were low energy and equal to approximately 75% of the defibrillation energy requirement (5.4 +/- 3.3 J), or to the defibrillation energy requirement plus 10 J (17.5 +/- 4.3 J). After the first two shocks, subsequent shocks were programmed to the maximum available energy (29.0 +/- 2.5 J). The alternate technique was used for the subsequent three inductions of VF. Postdefibrillation ventricular arrhythmias were noted. Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec were more frequent after a low-energy shock (19%), than after a high-energy shock (1.5%; P = 0.005). Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec were more frequent after a high-energy shock (32%), than after a low-energy shock (7.1%; P = 0.002). A relationship between the cycle length of the postdefibrillation ventricular arrhythmias and the absolute defibrillation energy was observed (P < 0.001; r = 0.6), and ventricular arrhythmias with a cycle length > 300 msec were uncommon after shocks < or = 10 J (P = 0.001). The characteristics of ventricular arrhythmias after maximum-energy shocks were similar to those that occurred after high-energy shocks. CONCLUSIONS: Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec are more common after shocks of strength associated with a low probability of successful defibrillation. Postdefibrillation ventricular arrhythmias with a cycle length of > 300 msec are more common after high- and maximum-energy shocks, and are directly related to the absolute defibrillation energy.
With use of transesophageal echocardiography, the short-term effects of transthoracic electrical cardioversion of atrial flutter (AFI) on atrial mechanical function and spontaneous echo contrast were determined. Thirty patients who had AFI for a mean of 6.4 +/- 12.2 months underwent transthoracic cardioversion. A transesophageal echocardiogram was recorded immediately before cardioversion, and left atrial appendage emptying velocity and spontaneous contrast were assessed serially at 1, 3, and 5 minutes after cardioversion in 28 patients, and also at 8, 10, and 15 minutes after cardioversion in a subgroup of 13 patients. Cardioversion was deferred in 2 patients (7%) because a thrombus was found in the left atrial appendage. Before cardioversion, spontaneous contrast was present in the left atrium in 7 of 28 patients (25%) who underwent cardioversion. The mean left atrial appendage emptying velocity of 54 +/- 22 cm/s before cardioversion fell by 26% to 40 +/- 25 cm/s at 1 minute after restoration of sinus rhythm (p <0.01). There were no significant changes in the mean left atrial appendage-emptying velocity between 1 and 15 minutes after cardioversion. Within 5 minutes after conversion to sinus rhythm, left atrial spontaneous echo contrast developed de novo or worsened in 12 of the 28 patients (43%). In conclusion, the results of this study demonstrate that persistent AFI may be associated with left atrial thrombi before cardioversion and that cardioversion of AFI is associated with a significant degree of atrial stunning and formation of spontaneous echo contrast.
BACKGROUND: The electrophysiologic effects of norepinephrine (NE) in human beings have not been previously described. METHODS: The electrophysiologic effects of NE infused at a rate of 25 ng/kg/min were determined in 21 patients with a mean age of 41 +/- 11 years and without structural heart disease who underwent an electrophysiology procedure. In a subgroup of 10 patients electrophysiologic parameters were measured at baseline, after the infusion of NE, and after administration of beta-blockade while in continuous NE infusion. RESULTS: The baseline NE plasma concentration of 298 +/- 153 pg/ml increased to 708 +/- 419 pg/ml after the infusion of NE. NE significantly increased the mean blood pressure, sinus cycle length, corrected sinus node recovery time, ventriculoatrial block cycle length, and the atrial and ventricular effective refractory periods. In a subset of 10 patients 0.2 mg/kg propranolol administered during continued infusion of NE resulted in a further increase in sinus cycle length, atrial-His interval, and ventricular refractoriness. CONCLUSION: A physiologic elevation in the plasma NE concentration results in a depression of sinus node function and atrioventricular conduction and in prolongation of atrial and ventricular refractoriness. Some of NE's effects are partially offset by beta-adrenergic stimulation.
PURPOSE: Adenosine is a useful agent for the diagnosis and termination of tachycardias. The purpose of this study was to identify the rhythms for which adenosine is prescribed in hospitalized adults and to identify the reasons for its misuse. PATIENTS AND METHODS: Data were collected from the medical records of 100 patients who received intravenous adenosine while hospitalized at a university medical center. The characteristics of the patients, rhythms treated with adenosine, and dosages of adenosine were analyzed. In addition, internal medicine house officers were administered a questionnaire referring to an electrocardiogram of atrial fibrillation with a rapid ventricular response. RESULTS: The arrhythmias for which adenosine was administered consisted of regular, narrow-QRS complex tachycardias in 33% of patients; atrial fibrillation in 32% of patients; regular, wide-QRS complex tachycardias in 23% of patients; atrial flutter in 10% of patients, and multifocal atrial tachycardia in 2% of patients. The mean (+/-SD) number of doses of adenosine given to each patient was 1.6+/-0.8, and the mean dose of adenosine was 7.8+/-2.8 mg. Internal medicine house officers prescribed 70% of the doses of adenosine and were as likely to use it for patients with atrial fibrillation as were surgical house officers. There was a 2% incidence of proarrhythmia, including asystole and polymorphic ventricular tachycardia. Thirty-one percent of the 100 house officers in our survey misdiagnosed a 12-lead electrocardiogram of rapid atrial fibrillation as paroxysmal supraventricular tachycardia, suggesting that adenosine may have been misused for atrial fibrillation because of errors in rhythm diagnosis. Only 5% of those who correctly diagnosed atrial fibrillation also answered that adenosine would be likely to terminate the arrhythmia, suggesting that a misunderstanding that adenosine terminates atrial fibrillation is not a common reason for its misuse. CONCLUSIONS: Approximately 40% of hospitalized adults who are treated with adenosine receive the medication unnecessarily for atrial fibrillation or atrial flutter, and this misuse results in unnecessary expenses and risks of adverse effects. The primary reason that adenosine is misused for atrial fibrillation is the inability to recognize that rhythm on an electrocardiogram. House officers need additional education on the electrocardiographic recognition of atrial fibrillation.
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No prior studies have evaluated the relationship between the site of right ventricular stimulation, the site of prior infarction, and the inducibility of ventricular tachycardia (VT). This study was performed to determine if the location of pathologic Q waves influences the inducibility of VT at various right ventricular sites in patients with coronary artery disease (CAD) and a history of myocardial infarction (MI). In 30 patients with a history of sustained, monomorphic VT, CAD, prior MI, and pathologic Q waves, programmed ventricular stimulation was performed at the right ventricular apex, septum, and outflow tract, in random order. There was electrocardiographic evidence of an MI that was inferior in 11 patients, anterior in 10 patients, and both inferior and anterior in 9 patients. Sustained, monomorphic VT was induced in 27 of 30 patients (90%). There were no significant differences among the three sites in the rate of inducibility of VT. The rate of inducible VT at each of the three right ventricular sites was not affected by the location of prior infarction. In conclusion, among patients with sustained, monomorphic VT, CAD, and a history of MI, the incidence of inducible sustained, monomorphic VT is not influenced by the location of prior infarction, regardless of whether programmed ventricular stimulation is performed at the right ventricular apex, septum, or outflow tract.
Ventricular pace mapping may be used to identify the site of origin of idiopathic ventricular tachycardia. Isoproterenol is often required to induce this type of ventricular tachycardia, but its effect on QRS morphology during pace mapping is unknown. Therefore, this study was performed to evaluate the effect of isoproterenol on QRS morphology during ventricular pacing. The study population consisted of 20 patients (mean age 38 +/- 14 years) undergoing a clinically indicated electrophysiology procedure. Ventricular overdrive pacing was performed in trains of 12 stimuli at cycle lengths of 400, 350, 300, and 250 ms, first in the baseline state during an infusion of isoproterenol, and again after isoproterenol washout. Pacing was performed at the right ventricular apex in 10 patients, in the right ventricular outflow tract in 6 patients, and in the left ventricle in 4 patients. Visual evaluation revealed no apparent effects of isoproterenol on QRS morphology at any of the three pacing sites or at any of the pacing cycle lengths. It was concluded that QRS morphology during ventricular pacing is not affected by isoproterenol infusion. Therefore, in patients with idiopathic ventricular tachycardia, even if the induction of tachycardia requires infusion of isoproterenol, successful pace mapping may be performed in its absence.