Disorders of left ventricular structure and function in chronic uremia: how often,why and what to do with it?

Left ventricular (LV) structure and function abnormalities are frequent in individuals with chronic uraemia; these disorders are at increased risk of cardiovascular and overall morbidity and mortality in the pre-dialyzed population, during dialysis treatment and in renal transplant recipients. This review will attempt to summarize current knowledge of the prevalence, pathophysiological mechanisms of LV disease in chronic uraemia and to discuss useful medical strategies in this population.     

When and how to assess an asymptomatic ventricular pre-excitation syndrome?

Sudden cardiac death may be the first event in the history of Wolff-Parkinson White syndrome: this is a very rare event although as ablation of the accessory pathway avoids this risk a potentially malignant form of the disease needs to be detected. Electrophysiological studies are the most reliable method. These may be performed by a trans-oesophageal or endocavity approach from the age of six to seven years onwards. Whilst it is rare to detect a potentially malignant form the results of these studies more often enable the person to play sports or continue their job without offering radio-frequency ablation. The former however is indicated when tachycardia is induced in children over 12 years old and in adults.     

What is healthcare-associated pneumonia and how is it managed?

PURPOSE OF REVIEW: Pneumonia developing before hospital admission in patients in close contact with the health system was recently termed 'healthcare-associated pneumonia' and proposed as a new category of respiratory infection. We focus on the recent literature concerning the epidemiology, causative organisms, antibiotic susceptibilities, and outcomes of and empirical antibiotic therapy for this condition. RECENT FINDINGS: The reported incidence of healthcare-associated pneumonia among patients requiring hospitalization for pneumonia ranges from 17% to 67%. Hospitalization within 90 days before pneumonia, attending a dialysis clinic and residing in a nursing home were the most common criteria for healthcare-associated pneumonia. Compared with patients with community-acquired pneumonia, those with healthcare-associated pneumonia are older, have greater co-morbidity, and are more likely to have aspiration pneumonia and pneumonia caused by antibiotic-resistant pathogens. Patients with healthcare-associated pneumonia also more frequently initially receive an inappropriate antibiotic therapy, have higher case fatality rates and have longer hospital stay. SUMMARY: Many patients hospitalized with pneumonia via the emergency department have healthcare-associated pneumonia. There are significant differences in the spectrum of causative organisms and antibiotic susceptibilities between healthcare-associated and community-acquired pneumonia. Physicians should differentiate patients with healthcare-associated pneumonia from those with community-acquired pneumonia to promote a targeted approach when selecting initial antibiotic therapy.     

Bone quality: what is it and how is it measured?

Bone quality describes aspects of bone composition and structure that contribute to bone strength independently of bone mineral density. These include bone turnover, microarchitecture, mineralisation, microdamage and the composition of bone matrix and mineral. New techniques to assess these components of bone quality are being developed and should produce important insights into determinants of fracture risk in untreated and treated disease.     

Mild left ventricular hypertrophy in essential hypertension: is it really arrhythmogenic?

Left ventricular hypertrophy (LVH) has been associated with an increased incidence of ventricular arrhythmias and sudden cardiac death in hypertensive patients. However, it is not known whether this relationship exists in early asymptomatic hypertensives with mild LVH. We prospectively examined 100 consecutive patients with essential hypertension, 35 without and 65 with mild LVH on echocardiography. All underwent a detailed noninvasive arrhythmia work-up and were subsequently followed-up for 3 ± 1 years in an ambulatory hypertension clinic. None of the 12-lead electrocardiographic parameters examined differed between the two hypertensive groups. A similarly low incidence of simple forms of ventricular ectopy was present in both groups, whereas complex forms of ventricular ectopy were extremely rare in either group. The signal-averaged electrocardiographic parameters examined were also not significantly affected by the presence of mild LVH. Arrhythmia-related symptoms or malignant ventricular arrhythmia events were not observed in either group of patients during follow-up with antihypertensive treatment. The latter resulted in LVH regression in the 65 patients with mild LVH at baseline. It appears that mild LVH among ambulatory hypertensive patients does not carry an additive arrhythmogenic risk and can be successfully reversed with the appropriate antihypertensive therapy, with no need of additional antiarrhythmic management.     

Is ventricular sensing always right,when it is left?

Background

Ventricular sensing in transvenous cardiac implantable electronic devices (CIEDs) occurs conventionally from the right ventricular (RV) channel, though it evolved from epicardial sensing both in pacemakers and implantable cardioverter‐defibrillators (ICDs).

Hypothesis

The objective of this study was to observe the reliability of left ventricular (LV) sensing by transvenous leads placed in coronary veins.

Methods

LV leads were used for sensing and arrhythmia detection in clinical situations where placement of an RV lead across the tricuspid valve was either not preferred or not feasible, or RV signal was unsuitable for arrhythmia detection, or in the event of sensing failure of an RV lead under advisory in cardiac resynchronization therapy defibrillator (CRTD) recipients.

Results

Thirty‐seven patients had an IS‐1 LV lead connected to the RV port of CIEDs (17 pacemakers, 5 cardiac resynchronization therapy pacemaker [CRTP], 2 ICDs, and 13 CRTDs). Along a median 41 (25‐67) months follow‐up, lead performance remained stable; there were neither undersensing nor oversensing of non‐cardiac signals. VT/VF were correctly detected and terminated by ATP and shocks (one and three patients, respectively); no inappropriate arrhythmia detection. Device reprogramming occurred in four CRTD recipients because of transient counting the QRS (short intervals) when paced in LV‐only, and in two with T‐wave oversensing.

Conclusions

Ventricular sensing by an LV lead is feasible in transvenous devices. Sensing programmability is an unmet need: to fix RV lead sensing issues in cardiac resynchronization therapy (CRT) recipients at no risk of infection (no pocket opening); to avoid interaction with the tricuspid valve; to avoid lead redundancy in the vasculature. Moreover, it will be mandatory owing to the loss of lead interchangeability due to the adoption of DF‐4 and quadripolar leads.     

The Arg16Gly polymorphism of the β2-adrenergic receptor and left ventricular systolic function

Backgroundβ-Adrenergic receptors (ARs), including β1- and β2-AR, are involved in modulation of cardiac contractility and heart rate. Arg16Gly, a functional polymorphism in the β2-AR gene, has been reported to influence exercise capacity in heart failure patients. This study examined the association of the β2-AR Arg16Gly polymorphism with left ventricular (LV) systolic function in a biethnic population-based sample.MethodsEchocardiograms and the β2-AR Arg16Gly polymorphism were analyzed in 267 normotensive (54% African Americans) and 252 severe hypertensive (53% African Americans) adults without coronary heart disease or diabetes.ResultsThe frequencies of Gly16Gly16, Arg16Gly16, and Arg16Arg16 were 28.1%, 54.3%, and 17.6%, respectively, in normotensives, and 31.4%, 47.6%, and 21.0%, respectively, in hypertensives. In normotensives, the Gly16Gly16 homozygotes displayed greater fractional shortening (35.9% ± 4.3% v 34.1% ± 4.7% v 34.0% ± 3.9%, P = .01), ejection fraction (65.0% ± 5.8% v 62.5% ± 6.4% v 62.6% ± 5.4%, P = .01), midwall shortening (18.6% ± 1.6% v 17.9% ± 1.9% v 18.0% ± 1.6%, P = .02), and stress-corrected midwall shortening (110.1% ± 9.3% v 106.1% ± 10.6% v 108.1% ± 10.8%, P = .03) compared to the Arg16Gly16 and Arg16Arg16 groups. These associations were independent of age, sex, ethnicity, heart rate, body mass index, systolic blood pressure, LV end-diastolic dimension, and field center. No significant associations between the β2-AR Arg16Gly polymorphism and echocardiographic measures were found in hypertensives.ConclusionsThe Arg16Gly polymorphism of β2-AR may be a marker for LV chamber function and contractility in normotensive adults.