Radiofrequency catheter ablation of ventricular arrhythmias in patients with hypertrophic cardiomyopathy

BACKGROUND

Compared to other non-ischemic substrates, there is limited data on the role and outcome of catheter ablation in HCM. The objective of this study is to assess the safety and efficacy of catheter ablation for the treatment of VT in patients with HCM.

METHODS

Fourteen patients with HCM and drug refractory VT who underwent catheter ablation at a single center were included in this study. The data was evaluated retrospectively. Acute success, procedure-related complications, and long-term outcomes were documented during follow up.

RESULTS

Among the 14 patients (mean age 48.2 ± 8.2 years, 85.7% males, mean LVEF 42.6 ± 6.5%), 4 had an apical aneurysm. Eleven patients had evidence of scar-related VT and three patients had a bundle-branch re-entry VT. The most common sites for scar-related VT were the border-zones of the apical aneurysms, basal septum, and LV lateral wall. Patient either underwent an endocardial ablation or a combined endocardial and epicardial ablation. Acute success was achieved in all patients. In 6 patients VT was terminated during ablation. In two patients, non-clinical VTs were inducible at the end of the procedure. No major or minor complications were observed during and after the procedure in all patients. During long-term follow up, elimination of VTs reached 78%.

CONCLUSION

Catheter ablation of VT in patients with HCM is safe and successful in eliminating VT. Combining endocardial and epicardial ablation techniques can potentially lead to better outcomes in these patients. Bundle branch re-entry should be considered as a potential mechanism of VT in patients with HCM.

Optimizing diastolic filling by pacing in nonobstructive hypertrophic cardiomyopathy

BACKGROUND

Treatment options for symptomatic patients with nonobstructive hypertrophic cardiomyopathy (nHCM) are limited.

OBJECTIVE

The purpose of this study was to determine the effect of sequential atrioventricular (AV) pacing, from different right ventricular (RV) sites with varying AV delays, on the diastolic function and functional capacity of patients with nHCM.

METHODS

Twenty-one patients with symptomatic nHCM and normal left ventricular (LV) systolic function were prospectively enrolled. Inclusion criteria included PR interval >150 ms, E/e' ≥15, and an indication for implantable cardioverter-defibrillator (ICD) implantation. Doppler echocardiographic study was performed during dual-chamber pacing at various AV intervals. Pacing was performed at 3 RV sites: RV apex (RVA), RV midseptum (RVS), and RV outflow tract (RVO). The site and sensed AV delay (SAVD) at which optimal diastolic filling occurred were chosen based on diastolic filling period and E/e'. During ICD implantation, the RV lead was implanted at the site identified by the pacing study. Devices were programmed in DDD mode at the optimal SAVD. During follow-up, diastolic function and functional capacity were assessed.

RESULTS

Among the 21 patients (age 47.8 ± 7.7 years; 81.0% male), baseline E/A and E/e' were 2.4 ± 0.6 and 17.2 ± 2.2, respectively. There was an improvement in diastolic function (E/e') in 18 patients (responders) when pacing from the RVA (12.9 ± 3.4; P <.001) than from the RVS (16.6 ± 2.3) and RVO (16.9 ± 2.2). Among responders, optimal diastolic filling occurred at SAVD of 130-160 ms with RVA pacing. Nonresponders had longer duration of symptoms (P = .006), lower LV ejection fraction (P = .037), and higher late gadolinium enhancement burden (P <.001). During 13.5 ± 1.5 months of follow-up, there was an improvement (Δ) in diastolic function (E/e' -4.1 ± 0.5), functional capacity (New York Heart Association functional class -1.5 ± 0.3), and reduction in N-terminal pro-brain natriuretic peptide level (-55.6 ± 12.3 pg/mL) compared to baseline.

CONCLUSION

Pacing at an optimized AV delay from the RVA improves diastolic function and functional capacity in a subset of patients with nHCM.

Common-law principles in consent for patients in oral and maxillofacial surgery who lack mental capacity: do we know them all?

Over the last 5 years, the medical profession has relied on the Bolam test for their defence in cases of clinical negligence. While still a matter of controversy between health professionals and legal experts, the Bolam test has been tried and criticised not only by the English courts but also in the United States, Canada, and Australia. In the medical profession the concept of the law of consent has moved away from a doctrine of professional paternalism towards patient-focused paternalism, and has increased the emphasis on human rights and the autonomy and choice of the patient. These changes present a challenge to health professionals, and a lack of effective recognition and interpretation can result in non-compliance. We review the developments in the law of consent since Bolam and discuss how they affect patients with incapacity, and highlight the importance of being familiar with them.

Should we be giving bilateral inferior alveolar and lingual nerve blocks for third molar surgery?

Extraction of mandibular third molars is one of the most common procedures in oral and maxillofacial surgery, and it is normal practice to extract both teeth at one visit under general anaesthesia. However, when both teeth are extracted under local anaesthesia, bilateral inferior alveolar and lingual nerve blocks are required, which is a subject of debate among clinicians. Much of the controversy surrounds the safety and efficacy of bilateral anaesthesia even though many surgeons use local anaesthetic solutions for perioperative and postoperative pain relief after day case general anaesthesia with no reports of unwanted effects. The evidence presented in this review explores published research for and against the use of unilateral and bilateral inferior alveolar and lingual nerve blocks.

The effect of dietary fiber on the bioavailability of digoxin in capsules

Sixteen healthy volunteers were regularly given 0.4 mg of digoxin daily as two capsules with breakfast. After ten days during which breakfast was supplemented with 11 g of bran fiber, steady-state predose mean serum digoxin was lower (0.89 +/- 0.19 versus 0.84 +/- 0.18 ng/mL, P less than .05) and mean 24-hour area under curve determination was lower (30.5 +/- 6.1 versus 28.4 +/- 6.0 ng X hr/mL, P less than .05) than during the control period without bran. Height and time of peak serum digoxin, and 24-hour urinary digoxin were not significantly different. The 6 to 7% reduction in digoxin absorption from capsules is less than that reported from tablets and is probably clinically unimportant.

Salivary concentrations of pirmenol as a possible cause of unpleasant taste

Salivary concentrations of the anti-arrhythmic, pirmenol, were compared with plasma concentrations in six patients. Group mean salivary values tended to be higher despite high plasma protein binding, suggesting the possibility of an active transport process. The observed salivary concentrations are reasonably close to those detectable in healthy volunteers as tasting unpleasant.