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Biomedical subjects

Maully J Shah

Publications and source records attributed to Maully J Shah.

13 recordsLinked to original sources

Induction of atrial fibrillation after the routine use of adenosine.

We report a case of atrial fibrillation induction after the use of adenosine for the termination of supraventricular tachycardia in the emergency department. Atrial fibrillation is not an uncommon side effect of adenosine administration. Hemodynamic collapse may occur if an antegrade-conducting accessory pathway allows for a rapid ventricular response. Therefore, we would recommend that the use of adenosine be limited to situations in which there is appropriate electrocardiographic monitoring and emergency resuscitative capabilities.

Adenosine↗

Multiple cardiac arrhythmias in a previously healthy child: a case of accidental digitalis intoxication?

We present a case of multiple arrhythmias in a 3-year-old child who was presented to the emergency department with emesis. Initial vital signs were significant for a heart rate from 40 to 60 beats per minute with stable blood pressure. An electrocardiogram showed complete atrioventricular block with a junctional escape rhythm of 40 to 55 bpm that subsequently progressed to atrial flutter/fibrillation and then to a junctional escape rhythm. She was given intravenous atropine, resulting in acceleration of the junctional rhythm. Sinus rhythm resumed with a prolonged PR interval a few hours later with normalization of the electrocardiogram the following day. Routine laboratory tests, toxicology screens, and tests for other cardiac medications in the home were negative. However, at 20 hours after presentation, her digoxin level was 2.9 ng/mL. Parents denied that the child had access to any digoxin-containing substances. This case illustrates that digoxin toxicity can manifest with multiple arrhythmias and that recognition of this can be very difficult, especially when there is no witness to ingestion. Clinicians should be suspicious for digoxin toxicity when a child presents with persistent emesis, altered level of consciousness, and bradyarrhythmias with or without hemodynamic instability.

Arrhythmias, Cardiac↗

Heart rate variability following neonatal heart surgery for complex congenital heart disease.

BACKGROUND: Altered cardiac autonomic control may play a role in the morbidity and mortality suffered by neonates who undergo surgery for complex congenital heart disease (CHD). The purpose of this study was to evaluate cardiac autonomic activity, as measured by spectral indices of heart rate variability (HRV), prior to and early after infant surgery for CHD and attempt to correlate HRV indices with clinical outcome. In addition, we assessed the hypothesis that single-ventricle physiology and surgical interruption of the great arteries negatively affects HRV. METHODS: Sixty neonates prospectively wore 24-hour Holter monitors at three time points: before and early after CHD surgery, and at 3- to 6-month follow-up. Standard spectral indices of HRV were measured. RESULTS: In the early postoperative time point, patients with single-ventricle physiology had lower low-frequency power (LF) compared to patients with two ventricles (P=0.040). Surgical interruption of the great arteries did not affect HRV in this cohort. For the entire cohort, LF (P=0.004) and high-frequency power (HF) (P<0.001) increased over the three time points, while LF/HF (P=0.119) did not significantly change. In the multivariable linear regression model, significant predictors of longer postoperative hospital stay included longer total support time (P=or<0.001), longer duration of inotrope support (P=0.012), elevated mean heart rate at postoperative time point (P=0.002), and lower LF/HF ratio at the postoperative time point (P=0.014). CONCLUSION: Patients with single-ventricle physiology have a significant physiologic reduction in LF in the early postoperative period compared to patients with two ventricles. Diminished cardiac autonomic control is associated with longer hospitalization following neonatal cardiac surgery.

Arrhythmias, Cardiac↗

Isolated unilateral absence of right proximal pulmonary artery: surgical repair and follow-up.

The isolated unilateral absence of a proximal pulmonary artery is a rare congenital lesion with a diverse clinical presentation. If the connecting ductus arteriosus closes after birth, the ipsilateral pulmonary artery will lose its source of blood supply, resulting in hypoplasia or obliteration of intrapulmonary vessels. Despite a seemingly benign early clinical course, a significant number of untreated patients will develop pulmonary hypertension, hemoptysis, and recurrent respiratory infections. Early detection and surgical repair provides restoration of physiologic pulmonary circulation, regression of pulmonary hypertension, and the potential for normal distal pulmonary vascular development.

Follow-Up Studies↗

Improved localization of right-sided accessory pathways with microcatheter-assisted right coronary artery mapping in children.

INTRODUCTION: Radiofrequency ablation of some right-sided accessory pathways continues to be challenging. The purpose of this study was to evaluate the efficacy of introducing a multielectrode microcatheter in the right coronary artery to localize accessory pathways when conventional mapping was unsuccessful. METHODS AND RESULTS: A retrospective study was conducted of all right-sided accessory pathway radiofrequency ablation procedures in which a multielectrode microcatheter as a reference in the right coronary artery was used to assist mapping. Between January 1998 and January 2002, 10 patients (5 males) underwent mapping of 11 accessory pathways with this technique at mean age of 12.3 +/- 3.8 years. Five patients had Ebstein's anomaly of the tricuspid valve. Accessory pathways were identified in the following locations: right anterior 3, right anterolateral 2, right lateral 1, right posterolateral 2, and right posterior 3. Mean procedure time was 285 +/- 70.3 minutes, and fluoroscopy time was 68.7 +/- 21 minutes. Average mapping duration prior to microcatheter insertion in the right coronary artery was 136 +/- 40 minutes. After microcatheter placement in the right coronary artery, the time to successful ablation of accessory pathways was 38 +/- 11 minutes. All 11 (100%) accessory pathways were successfully ablated. CONCLUSION: Mapping in the right coronary artery with a microcatheter is an effective method to improve localization and successful ablation of difficult right-sided accessory pathways.

Adolescent↗

Endocardial atrial pacing lead implantation and midterm follow-up in young patients with sinus node dysfunction after the fontan procedure.

The purpose of the study was to investigate the results of endocardial lead implantation, lead performance, and follow-up in young patients after the Fontan procedure. A retrospective study was conducted with patients who had endocardial atrial pacing for SND and intact AVN function after Fontan from two pediatric centers. Patient demographics, pacing, and sensing data of endocardial atrial leads were analyzed at the time of pacemaker implantation and follow-up visits. Fifteen patients (weight 42.6 +/- 35 kg) had transvenous endocardial atrial lead implantation at an average age of 11.4 +/- 6.5 years. Active-fixation leads were used in all patients and steroid elution was present in 12 (80%) patients. Adequate P wave sensing was obtained in patients with sinus rhythm (n = 10); the remaining four patients had junctional rhythm without measurable P waves. Lead failure was not observed in any patient during the follow-up period of 2.9 +/- 2.1 years. The energy threshold at implantation was 1.46 +/- 1.5 microJ, 1.54 +/- 0.75 microJ at 3 months, 0.62 +/- 0.45 microJ at 1 year, 0.72 +/- 0.65 microJ at 2 years, 0.75 +/- 0.55 microJ at 3 years, and 0.8 +/- 0.85 microJ at 5 years postimplant. The lead impedance was 648 +/- 298 omega at implantation, 714 +/- 163 omega at 3 months, 744 +/- 195 omega at 1 year, 734 +/- 198 omega at 2 years, 800 +/- 142 omega at 3 years and 830 +/- 200 omega 5 years postimplant. Anticoagulation therapy (aspirin n = 5, warfarin n = 8) was continued by 13 patients. Complications consisted of a pneumothorax at implantation and a transient ischemic attack in one patient 4 years after pacemaker implant. Endocardial atrial leads offer low energy thresholds and can be implanted relatively safely in Fontan patients.

Adolescent↗

Temporary transvenous pacing with an active fixation bipolar lead in children: a preliminary report.

Various techniques and electrode catheters have been developed for effective and safe temporary transvenous cardiac pacing. In neonates and children, lead dislodgment and myocardial perforation have been attendant risks with passive fixation leads. We report our experience with the recently introduced Medtronic 6416 active fixation bipolar lead in a small group of children. Between January 2000 and February 2002, 4 children (2 boys, 2 girls) underwent temporary transvenous pacing with the Medtronic 6416 lead. The median age at implantation was 4.25 years (range: 5 days-13 years), median weight was 14.5 kg (range: 2.5 kg-54 kg) and the median duration of temporary pacing was 19.5 days (range: 5-38 days). The indication for temporary pacing was AV block (n = 2), sinus arrest (n = 1) and sinus node dysfunction (n = 1). The acute pacing threshold was <1.5 mA with no significant rise in the follow-up period. The venous access for lead placement was femoral vein (n = 2), internal jugular vein (n = 1), and subclavian vein (n = 1). There were no complications related to implantation or in the follow-up period. The Medtronic 6416 lead appears to be a safe and effective tool in temporary transvenous pacing in neonates and children.

Adolescent↗

Efficacy of implantable loop recorders in establishing symptom-rhythm correlation in young patients with syncope and palpitations.

OBJECTIVE: To evaluate efficacy of the recently introduced implantable loop recorder (ILR) in establishing symptom-rhythm correlation in young patients with syncope, near syncope, palpitations, and acute life-threatening events (ALTEs). METHODS: A retrospective study was conducted with patients with ILR from 3 pediatric centers. Inclusion criteria were age <or=25 years and a minimum follow-up of 1 month. All ILR-stored events were analyzed regularly for the presence or absence of an arrhythmia at the time of the symptomatic event. RESULTS: Twenty-one patients (12 male, 9 female) with an average age of 12.3 +/- 5.3 years (range: 0.8-22 years) were included in the study. Five (24%) patients had structural heart disease, 2 (10%) had a family history of sudden cardiac death, 3 (14%) had QT prolongation on electrocardiogram, and 11 had no cardiovascular disease. Indications for ILR were recurrent syncope and near syncope (n = 15), palpitations (n = 2), and ALTE (n = 2). Fourteen (67%) patients continued to have symptoms, and 7 (33%) had no symptoms after ILR over a follow-up period of 8.4 +/- 4.7 months (range: 1.9-16 months). Symptom-rhythm correlation was possible in all 14 patients who continued to have symptoms (supraventricular tachycardia in 4, ventricular tachycardia in 2, torsades de points in 1, asystole in 1, junctional bradycardia in 1, and sinus rhythm in 5). CONCLUSIONS: ILR is useful in determining the presence or absence of an arrhythmia during symptoms of syncope, near syncope, and palpitations as well as ALTEs in patients with and without structural heart disease when conventional diagnostic testing, such as electrocardiogram, Holter monitoring, and/or external loop recording, is inconclusive.

Adolescent↗