Amlodipine alters hemorheological parameters: Increased efficacy at the cost of edema?

Background Despite several decades of use of calcium channel blockers, the side effect of edema persists as a class effect, and its mechanism is unresolved. Amlodipine has effects on hemorheology (HR), and its hemodilutory property may partly contribute to its antihypertensive action. This aspect is not well studied, and the literature is sparse in this regard. Objective This experiment was planned to determine effect of a single-dose administration of amlodipine on HR parameters in normal human volunteers. Methods and results Amlodipine (5 mg) or S (-) amlodipine (2.5 mg) was administered to 27 normal human volunteers. Whole-blood viscosity (WBV) at different shear rates, plasma viscosity (PV), red cell rigidity (RCR), red cell aggregation (RCA), hematocrit (Hct), plasma hemoglobin, along with plasma drug concentration were determined at time intervals, t = 0, 4, 8, 12, and 24 h. Statistically significant reductions were observed at tmax = 4 h in WBV at shear rates of 0.512 s–1 (p < 0.005), WBV at shear rates of 5.26 s–1 (p < 0.01), PV (p < 0.05), and Hct (p < 0.01). At t = 8 h, as drug concentration reduced, some of the changes persisted and later slowly decreased with the decreasing drug concentration till t = 24 h. Red blood cell–related parameters such as RCA and RCR remained unaltered. WBV values at all shear rates, when corrected for Hct = 0.45, did not show deviation from their original values at any time. Conclusions Amlodipine causes a reduction in Hct and blood viscosity, along with hemodilution. These effects persist as long as the drug remains in plasma. Edema resulting from chronic dosing may be explained by the aforementioned effects. It is possible that antihypertensive action of the drug may be due to a combination of vasodilatation and an improvement in the HR properties.

Routine health check-ups: A boon or a burden.

Healthcare provider institutions in India now offer structured health check-up ‘packages’ for routine screening of common diseases. While some tests included within their ambit are in keeping with international and Indian recommendations, some are entirely unwarranted. Unnecessary and inappropriate screening tests may cause more harm than benefit. Besides financial and resource burden, there may be over-diagnosis and over-treatment, psychological distress due to false-positive test results, harm from invasive follow-up tests, and false reassurance due to false-negative test results. Clinicians must ensure a net benefit from tests and interventions in order to efficiently deliver preventive services. We reviewed current screening guidelines for cardiovascular disease and common cancers, and surveyed multiple ‘packages’ provided at 8 centres in Mumbai, India. We put forth our recommendations for routine health screening in asymptomatic adults in India. Natl Med J India 2016;29:18–21

Morphological abnormalities in baseline ECGs in healthy normal volunteers participating in phase I studies.

Background & objectives: Morphological abnormalities in 12-lead electrocardiograms (ECGs) are seen in subgroups of healthy individuals like athletes and air-force personnel. As these populations may not truly represent healthy individuals, we assessed morphological abnormalities in ECG in healthy volunteers participating in phase I studies, who are screened to exclude associated conditions. Methods: ECGs from 62 phase I studies analyzed in a central ECG laboratory were pooled. A single drug-free baseline ECG from each subject was reviewed by experienced cardiologists. ECG intervals were measured on five consecutive beats and morphological abnormalities identified using standard guidelines. Results: Morphological abnormalities were detected in 25.5 per cent of 3978 healthy volunteers (2495 males, 1483 females; aged 18-76 yr); the presence was higher in males (29.3% vs. 19.2% in females; P<0.001). Rhythm abnormalities were the commonest (11.5%) followed by conduction abnormalities (5.9%), axis deviation (4%), ST-T wave changes (3.1%) and chamber enlargement (1.4%). Incomplete right bundle branch block (RBBB), short PR interval and right ventricular hypertrophy were common in young subjects (<20 yr) while atrial fibrillation, first degree atrioventricular block, complete RBBB and left anterior fascicular block were more prevalent in elderly subjects (>65 yr). Prolonged PR interval, RBBB and intraventricular conduction defects were more common in males while sinus tachycardia, short PR interval and non-specific T wave changes were more frequent in females. Interpretation & Conclusions: Morphological abnormalities in ECG are commonly seen in healthy volunteers participating in phase I studies; and vary with age and gender. Further studies are required to determine whether these abnormalities persist or if some of these disappear on follow up.

Successful RF ablation of atrial tachycardia from the non-coronary aortic cusp.

A 51-year-old lady presented with recurrent episodes of supraventricular tachycardia since 1 year. EP study revealed easily inducible atrial tachycardia. Endocardially, the earliest activation site was found in the His bundle region (-18 ms). The aorta was therefore mapped, and a site in the non-coronary cusp was found with an activation time of -30 ms. RF energy at this site successfully eliminated tachycardia. She is asymptomatic at 8 months of follow-up, without any anti-arrhythmic drug.

Incessant atrial flutter after device closure of atrial septal defect: successful radio frequency ablation.

A four-month-old baby presented with failure to thrive and congestive cardiac failure precipitated by a lower respiratory tract infection. He was found to have a large ostium secundum atrial septal defect measuring 18 mm. This was successfully closed percutaneously by a device (Blockaid). A month after the device deployment the child developed typical atrial flutter. Despite rate control drugs the ventricular rate remained l40/min over the next several months. In view of the incessant atrial flutter with fast ventricular response, the child underwent radiofrequency ablation at the age of 2 years. An isthmus block was created which successfully terminated the tachycardia.

'Hibernating' accessory pathway.

A 13-year-old boy presented with recurrent narrow QRS tachycardia from which he had been suffering for one year. An electrophysiology study revealed a concealed left lateral accessory pathway with inducible orthodromic atrioventricular re-entry tachycardia using the same pathway. The accessory pathway was ablated in January 2004. After the ablation, atrioventricular block was demonstrated (with adenosine), as was ventriculo-atrial block, and the patient had paroxysmal tachycardia one month later. This time, however, the electrocardiogram in sinus rhythm showed a negative delta wave in V1, suggestive of a right-sided accessory pathway. Another electrophysiology study showed no conduction across the left accessory pathway found earlier. The right accessory pathway, which had 'emerged' after the ablation, had an antegrade effective refractory period of 440 msec and a retrograde effective refractory period of <250 msec. Orthodromic atrioventricular re-entry tachycardia using this accessory pathway was easily inducible. The tricuspid annulus was mapped and the second accessory pathway was localized to the right anterolateral region. This was ablated successfully. This is a unique instance of a symptomatic 'hibernating' accessory pathway emerging in adolescence.

Heart failure: a unique presentation of typical atrioventricular nodal reentrant tachycardia.

Cardiomyopathy due to various ventricular and supraventricular arrhythmias, including isolated cases of atypical atrioventricular nodal reentrant tachycardia, have been described. In this case report typical slowfast atrioventricular nodal reentrant tachycardia resulting in cardiomyopathy is being documented for the first time. In the setting of depressed left ventricular function, an episode of tachycardia pushed this patient into heart failure. Radiofrequency ablation of the slow pathway was successful in eliminating her tachycardia with the return of left ventricular function to normal. A follow-up of two years post-ablation revealed the patient to be symptom-free.

'Rescue' radiofrequency ablation for atrial tachycardia presenting as cardiomyopathy in pregnancy.

A young primiparous lady presented with drug-refractory atrial tachycardia which had led to cardiomyopathy. Three attempts with electrical cardioversion were also unsuccessful. She was rescued by radiofrequency ablation.

Control of rate versus rhythm in rheumatic atrial fibrillation: a randomized study.

BACKGROUND: Patients with rheumatic heart disease and atrial fibrillation incur significant morbidity and mortality. It is not known which approach, rate control or maintenance of sinus rhythm might be most appropriate. The present study was undertaken to compare the strategy of ventricular rate control versus maintenance of sinus rhythm in rheumatic atrial fibrillation, and to evaluate the role of amiodarone in this patient population. METHODS AND RESULTS: We prospectively studied 144 patients with chronic rheumatic atrial fibrillation in a double-blind protocol-rhythm control (group I: 48 patients each with amiodarone -group Ia; and placebo -group Ib) and compared the effects with the ventricular rate control (group II) by diltiazem (n=48, open-label). Direct current cardioversion was attempted in group I. The mean age of the study population was 38.6+/-10.3 years, left atrial size was 4.7+/-0.6 cm, atrial fibrillation duration was 6.1+/-5.4 years, and 72.9% patients had undergone valvular interventions. At 1 year, 45 patients with sinus rhythm in group I compared to 48 patients in group II demonstrated significant increase in exercise to sinus rhythm time, had improvement in functional class and quality of life score. There was no difference in hospitalization rates, systemic bleeds or incidence of thromboembolism. Five patients died in group II but none in group I (p=0.02). In group I, 73/87 (83.9%) patients converted, and 45/86 (52.3%) patients maintained sinus rhythm at 1 year. Conversion rates were 38/43 (88.4%) with amiodarone versus 34/44 (77.3%) with placebo (p=0.49): corresponding rate for maintaining sinus rhythm was 29/42 (69.1%) versus 16/44 (36.4%), p=0.008 respectively. CONCLUSIONS: Maintenance of sinus rhythm appeared to be superior to ventricular rate control in patients with rheumatic atrial fibrillation in terms of an effect on mortality and morbidity. Sinus rhythm could be restored in the majority and amiodarone was superior to placebo in this regard.

Does device-based testing save time during automatic implantable cardioverter-defibrillator implantation?

BACKGROUND: Defibrillation testing can be done either via an external cardiac defibrillator or directly via the implanted defibrillator during implantation (device-based testing). The advantage of one testing methodology over the other has not been adequately studied. METHODS AND RESULTS: Seventy-four patients (72% men) were randomized into two groups depending on the defibrillation testing methodology used--external cardiac defibrillation and device-based testing groups. R-wave, pacing threshold, pacing impedance, defibrillation threshold, defibrillation pathway impedance and total procedure time were not significantly different between the two groups. CONCLUSIONS: Device-based testing did not significantly reduce the procedure time. Lead and defibrillation parameters were similar in both the groups; lead repositioning and replacement were required in three patients in the external cardiac defibrillation group.

Radiofrequency ablation of incessant orthodromic tachycardia in a young child with a univentricular heart.

The incidence of supraventricular tachycardia is high in infants and children with congenital heart disease. We report a case of incessant orthodromic tachycardia in a child with a univentricular heart, which was successfully treated with radiofrequency ablation.

Tachycardiac storm in infant with WPW syndrome: "rescue" radiofrequency ablation.

A two-month-old child having WPW syndrome and orthodromic tachycardia was on treatment with digoxin, flecainide and amiodarone. Despite this, he continued to have severe, very frequent episodes of tachycardia. The left-sided accessory pathway was hence ablated via a patent foramen ovale.

Tachyarrhythmias: the era of cure.

Radiofrequency ablation for tachyarrhythmias is a treatment modality, in the recent times, which has permanently cured the patients. The subject is discussed here in some details.

Radiofrequency ablation of incessant atrial tachycardia in an infant.

Ectopic automatic atrial tachycardia, an uncommon type of supraventricular tachycardia in children and adults, has been reported to be resistant to medical therapy unlike reentrant supraventricular tachycardia. We report a case of incessant atrial tachycardia in an infant, which was successfully treated with radiofrequency catheter ablation.

Catheter ablation of atrial tachycardia using a real-time position management mapping system.

Catheter ablation for atrial tachycardia is limited by its low success rate and prolonged procedure time because of difficulties in mapping the site of the tachycardia. A new three-dimensional mapping system, the Cardiac Pathways mapping system, using an ultrasound transducer, has recently become available. We report a case of focal atrial tachycardia ablation with this system.

Effect of weight loss on QT dispersion in obesity.

BACKGROUND: Sudden cardiac death in patients on a liquid protein diet has been suggested to be related to repolarization abnormalities. Although increased QT dispersion is also associated with sudden cardiac death, it has not been examined in the setting of weight loss using liquid protein diet. METHODS AND RESULTS: Sixty-three patients (mean age 42 years, 18 men) with a mean initial weight of 116 kg were randomly chosen from patients who had completed 26 weeks of liquid protein diet therapy. QT, corrected QT interval, QT dispersion and corrected QT dispersion were measured blindly along with serum albumin and electrolytes at the beginning and end of 26 weeks of liquid protein diet therapy. In 57 patients (89.5%) (group 1), QT dispersion shortened after weight loss while it was prolonged in 6 patients (10.5%) (group 2). The mean weight loss (group 1: 115+/-21 to 91+/-16 kg; group 2: 122+/-21 to 98+/-13 kg), and serum albumin and electrolyte levels before weight loss were the same in both groups. The decrease in QT dispersion in group 1 was due to increase in the minimum QT interval (350+/-22 v. 375+/-21 mis, p<0.01) after weight loss. However, the QT dispersion increase in group 2 was due to prolongation of the maximum QT interval (402+/-27 v. 441+/-19 ms, p<0.05) after weight loss. This suggests that shortening of the minimum QT interval causes the increased QT dispersion in obesity. Half the patients in group 2 showed a drop in the serum albumin level and 2 patients had an abnormally high phosphorous level at the end of the treatment. CONCLUSIONS: QT dispersion shortens in most patients (89.5%) using liquid protein diet for weight loss. However, increase of QT dispersion is seen in 10.5% of patients. The cause of increased QT dispersion in obesity (before weight loss) differs from that in patients after weight-loss using liquid protein diet. QT dispersion changes observed in this study may explain the risk of sudden cardiac death in these patients.