Implantable cardioverter defibrillator: what a hospital practitioner needs to know.

The implantable cardioverter defibrillator (ICD) has undergone a remarkable transformation in the last three decades, both in generator size and functionality. This, coupled with improvements in lead design, allows the simplicity of defibrillator implantation to approach that of pacemakers, with outpatient placement now feasible. Nowadays, the majority of new ICD implants are performed on primary prevention grounds with device longevity of more than 7 years. In this article, we will concisely explain the evolution of this treatment, the implantation technique, arrhythmia detection and patient follow-up. In addition, we will review the relevant clinical trials as well as prescription guidelines.

The simultaneous use of a biventricular implantable cardioverter defibrillator (ICD) and transcutaneous electrical nerve stimulation (TENS) unit: implications for device interaction.

Undesirable sensing of external sources of electromagnetic interference by ICDs is well known. A transcutaneous electrical nerve stimulation (TENS) device has been reported to interfere with an ICD resulting in an inappropriate shock and patients with implanted defibrillators or pacemakers have been cautioned about the use of such units to treat chronic pain. We describe a patient regularly using TENS therapy for pain who subsequently received a biventricular ICD for malignant ventricular arrhythmias and medically refractory cardiac failure. He underwent testing for device interaction immediately post-implant. This did not show inappropriate sensing by either ICD or pacemaker component of his heart failure device. However, six months later, the patient complained of dizziness and bradycardia with application of TENS. Further testing did reveal interference with pacemaker function. Thus, even if initial testing is negative and reassuring, patients with a biventricular ICD still require careful follow-up for potential interaction and should be cautioned against the use of TENS, especially if they are pacemaker-dependent.

Long-term survival after permanent pacemaker implantation: analysis of predictors for increased mortality.

AIMS: To determine long-term time-related survival and evaluate risk factors for increased mortality in patients following their first permanent pacemaker implantation. METHODS AND RESULTS: Analysis of patient records from implant to follow-up. Patient-specific time-lines were constructed to date of last review or death. Observed survival was estimated by event-free analysis using the Kaplan-Meier method. Expected survival was derived from age- and gender-matched cohorts. Risk factors for mortality were sought using the multivariate Cox proportional hazards method and risk ratios estimated. Eight hundred and thirty-three patients underwent implantation of their first permanent pacemaker from April 1992 to January 1994, and were locally followed up. Survival data were available for 803 (96.4%) patients (median age, 77.3 years [5th to 95th centile range: 53.5 to 89 5 years]) and follow-up was complete in 94.8%. At implant. dual-chamber systems were implanted in 443 (55.1%). single-chamber ventricular systems in 321 (40.0%), and single-chamber-atrial systems in 39 (4.9%). Observed survival after implantation was significantly worse than expected (P<0.001). Independent predictors of increased mortality were: age at implant (risk ratio [RR] 1.06: 95% confidence interval [CI] 1.01 to 1.12). VVI pacing mode (RR 1.64; 95% CI 1.34 to 1.93), cardiomyopathy (RR 5.86; 95% CI 4.86 to 6.86), male gender (RR 1.27; 95% CI 1.22 to 1 32) and valvular heart disease (RR 2.01: 95% CI 1.98 to 2.04). CONCLUSIONS: At the end of follow-up, mortality was much higher than expected. In this typical pacemaker population. age at implant and VVI pacing mode were independently associated with increased mortality with accompanying heart disease having the greatest individual impact.

An echocardiographic assessment of cardiac morphology and common ECG findings in teenage professional soccer players: reference ranges for use in screening.

OBJECTIVE: To assess physiological cardiac adaptation in adolescent professional soccer players. SUBJECTS AND DESIGN: Over a 32 month period 172 teenage soccer players were screened by echocardiography and ECG at a tertiary referral cardiothoracic centre. They were from six professional soccer teams in the north west of England, competing in the English Football League. One was excluded because of an atrial septal defect. The median age of the 171 players assessed was 16.7 years (5th to 95th centile range: 14-19) and median body surface area 1.68 m(2) (1.39-2.06 m(2)). MAIN OUTCOME MEASURES: Standard echocardiographic measurements were compared with predicted mean, lower, and upper limits in a cohort of normal controls after matching for age and surface area. Univariate regression analysis was used to assess the correlation between echocardiographic variables and the age and surface area of the soccer player cohort. ECG findings were also assessed. RESULTS: All mean echocardiographic variables were greater than predicted for age and surface area matched controls (p < 0.001). All variables except left ventricular septal and posterior wall thickness showed a modest linear correlation with surface area (r = 0.2 to 0.4, p < 0.001); however, left ventricular mass was the only variable that was significantly correlated with age (r = 0.2, p < 0.01). Only six players (3.5%) had structural anomalies, none of which required further evaluation. All had normal left ventricular systolic function. Sinus bradycardia was found in 65 (39%). The Solokow-Lyon voltage criteria for left ventricular hypertrophy were present in 85 (50%) and the Romhilt-Estes points score (five or more) in 29 (17%). Repolarisation changes were present in 19 (11%), mainly in the inferior leads. CONCLUSIONS: Chamber dimensions, left ventricular wall thickness and mass, and aortic root size were all greater than predicted for controls after matching for age and surface area. Sinus bradycardia and the ECG criteria for left ventricular hypertrophy were common but there was poor correlation with echocardiographic left ventricular hypertrophy. The type of hypertrophy found reflected the combined endurance and strength based training undertaken.

Abnormal liver function tests following inadvertent inhalation of volatile hydrocarbons.

The use of aerosols containing volatile hydrocarbons in conditions of poor ventilation can result in accidental overexposure which can cause central nervous system effects and hepatic injury. We present a case in which inadvertent usage of an adhesive spray used to make greeting cards resulted in vague neurological symptoms and abnormal liver function tests both of which fully resolved on discontinuation.