Improvement in Cheyne-Stokes respiration following cardiac resynchronisation therapy.

The effect of standard cardiac resynchronisation therapy (CRT) on the severity of Cheyne-Stokes respiration (CSR) in patients with congestive heart failure was studied. It was hypothesised that CRT, through its known beneficial effects on cardiac function, would stabilise the control of breathing and reduce CSR. Twenty-eight patients who were eligible for CRT and receiving optimised medical treatment for congestive heart failure were referred for overnight polysomnography, including monitoring of thoracic and abdominal movements to identify CSR and obstructive sleep apnoea events. Patients underwent repeat polysomnography after 6 months of CRT to re-evaluate sleep quality and sleep-disordered breathing. Twelve of the 28 patients had significant CSR (43%); 10 patients had a successful implantation and underwent repeat polysomnography a mean+/-SD 27+/-7 weeks after continuous biventricular pacing. Six of the 10 patients experienced a significant decrease in CSR severity following CRT, associated with correction of congestive heart failure-related hyperventilation and hypocapnia. Circulation time, oxygen saturation, frequency of obstructive apnoeas and sleep quality did not change. In conclusion, cardiac resynchronisation therapy is associated with a reduction in Cheyne-Stokes respiration, which may contribute to improved clinical outcome in patients treated with cardiac resynchronisation therapy.

Different patterns of interatrial conduction in clockwise and counterclockwise atrial flutter.

BACKGROUND: The terms counterclockwise (CC) and clockwise (C) atrial flutter (Afl) are used to describe right atrial activation around the tricuspid valve in the left anterior oblique view. The manner in which the left atrium is activated, as reflected by coronary sinus (CS) recordings, has not been systematically evaluated. METHODS AND RESULTS: Nine patients with both CC and C Afl underwent electrophysiological study with CS recordings during both rhythms with the use of a decapolar catheter with the tip placed in the distal CS. Patterns of CS activation during each type of Afl as well as during during sinus rhythm were categorized into 1 of 3 patterns: sequential proximal-to-distal, sequential distal-to-proximal, and fused, indicating activation from different directions. In 7 of 9 patients, the pattern of CS activation in CC Afl and C Afl differed, with a proximal-to-distal pattern in CC Afl and a fused pattern in C Afl. In 2 patients, pacing the high right atrial septum near the presumed site of Bachmann's bundle in sinus rhythm showed a similar fused pattern of CS activation. CONCLUSIONS: These results demonstrate different patterns of CS activation in CC Afl and C Afl in the majority of patients and are consistent with a model in which the left atrium is activated predominantly over Bachmann's bundle during C Afl and over the CS os in CC Afl. These findings may have implications for maintenance of Afl, interpretation of flutter wave morphology on surface ECG, and left atrial mechanical function in Afl.

Incidence and predictors of myocardial infarction among patients with atrial fibrillation.

OBJECTIVES: We sought to evaluate the utility of excluding myocardial infarction (MI) in patients presenting to the emergency department (ED) with atrial fibrillation (AF) and to identify predictors of MI in this group. BACKGROUND: Patients with AF are frequently admitted to the hospital, in part, to exclude an associated MI. There are no prospective data on unselected patients to support this common practice. METHODS: We conducted a prospective cohort study of all patients who presented to a single-center ED with the primary diagnosis of AF. RESULTS: Of a total of 255 patients, 190 (75%) were admitted to the hospital, and 109 of them underwent a standard "rule-out MI" protocol. Of these 109 patients, six (5.5%) were identified as having an acute MI at the time of admission. Chest pain was present in 39% of patients, with a sensitivity and specificity for the occurrence of MI of 100% and 65%, respectively. ST segment elevation or depression was present in 43% of patients, with a sensitivity and specificity of 100% and 51%. The presence of either major ST segment depression (>2 mm) or elevation on the admission electrocardiogram (ECG) was present in 6%, with a sensitivity of 100% and a specificity of 99%. The resulting positive and negative predictive values were 86% (95% confidence interval [CI] 42% to 99%) and 100% (95% CI 96% to 100%), respectively. Use of this criterion would have reduced the number of rule-out MIs in our study group by 94%, with no loss of sensitivity. CONCLUSIONS: Chest pain and ST segment depression are extremely common findings in patients presenting to the ED with AF and have limited power to predict MI. In contrast, ECG evidence of ST segment elevation or depression >2 mm appears to be a reliable discriminator of which patients are at risk for MI. Patients without significant ST segment changes are at very low risk for MI and may not require performance of the rule-out MI protocol or hospital admission if clinically stable.

A novel indication for transvenous lead extraction: upgrading implantable cardioverter defibrillator systems.

UNLABELLED: Technological advances have resulted in the development of dual chamber pacemaker/defibrillator systems with smaller pectoral 'active cans'. Patients now have the option of upgrading from abdominal to pectoral or from single to dual chamber devices. In addition, due to the potential complications which may arise with abandoned ICD leads, extraction of preexisting leads may be preferable. METHODS AND RESULTS: Twenty consecutive patients (11 males), underwent lead extraction and upgrade, either from an abdominal to a pectoral, or from a single to a dual chamber device. The mean age was 62+/-18 years and mean implant duration was 50+/-14 months. Indications for extraction included lead fracture/malfunction (13), ERI/EOL (2), new SVT/VT (2), long charge times (2), and impending erosion (1). An initial attempt was made to remove the lead with gentle traction. If excessive scar tissue prohibited extraction, then a laser sheath was employed. Reimplantation proceeded following standard protocol. Clinical success was achieved in all patients. Eleven of thirty leads were removed with traction. The remaining 19 leads required removal with the laser sheath. All ICD reimplants were placed in the left pectoral position, of which 10 were dual chamber. The mean defibrillation threshold was 9.5+/-5.8 Joules. There were no procedure related perforations or deaths. At follow up (13+/-10 mos. ) there were no infections, lead malfunctions or venous thromboses. There were two deaths, both from intractable heart failure. CONCLUSIONS: This study demonstrates that, when indicated, ICD leads can be safely extracted and systems successfully upgraded to take advantage of new technology.

Three-dimensional echocardiography improves accuracy and compensates for sonographer inexperience in assessment of left ventricular ejection fraction.

This study was performed to determine whether 3-dimensional echocardiography (3DE) with a magnetic tracking system for image plane localization, which unlike standard 2-dimensional echocardiography (2DE), does not require acquisition of specific image planes or "standard views" for quantitative measurement of left ventricular volume and ejection fraction (EF), could compensate for sonographer inexperience. Eight adults underwent magnetic resonance imaging (MRI) scanning; they also had 2DE and 3DE performed by 2 experienced and 3 novice sonographers. Data were analyzed by a single expert reader blinded to patient and sonographer identity. Linear regression of MRI EF (reference standard) against echocardiographic EF yielded the following results, where RD indicates the residual difference between measured MRI values and those predicted using echocardiographic results: expert 3DE: r = 0.97, RD = 2.4%, and r = 0.96, RD = 2.8%; novice 3DE: r = 0. 83, RD = 5.1%, to r = 0.95, RD = 4.8%; expert 2DE: r = 0.85, RD = 4. 8%, and r = 0.86, RD = 4.9%; and novice 2DE: r = 0.34, RD = 11.7%, to r = 0.69, RD = 6.6%. Comparison of error variances indicated that novices who used 3DE equaled the performance of experts who used 2DE, although experts were always more accurate than novices when both used the same echocardiographic method (3DE vs 3DE, 2DE vs 2DE). In a comparison of methods, 3DE was always superior to 2DE, regardless of sonographer experience. Three-dimensional echocardiography allows even novice sonographers to obtain diagnostic-quality data sets, which they were unable to accomplish with 2DE. These results suggest that scanning with 3DE, combined with remote expert interpretation, may be useful in providing echocardiographic services in regions where they are presently unavailable.

Increased urinary leukotriene excretion in patients with cardiac ischemia. In vivo evidence for 5-lipoxygenase activation.

BACKGROUND: Experimental cardiac ischemia in some animal models results in the activation of the enzyme 5-lipoxygenase and the subsequent production of leukotrienes, potent proinflammatory lipid mediators, by the affected myocardium. Furthermore, prototype antileukotriene drugs can show some beneficial effects on infarct size and cardiac function in these models. Accordingly, urinary excretion of leukotriene E4 (LTE4), the major urinary metabolite of peptide leukotrienes in humans, was measured in patients admitted to the hospital with evidence of acute myocardial ischemia to assess in vivo release of 5-lipoxygenase products during and after the ischemic episode. METHODS AND RESULTS: Urinary leukotriene excretion was measured by reversed-phase high-performance liquid chromatography and specific radioimmunoassay on admission with acute chest pain and again on day 3 in the following patient groups: acute myocardial infarction (AMI), AMI and clinical evidence of early reperfusion after treatment with recombinant tissue-type plasminogen activator (rt-PA), diagnosis of unstable angina (UA) based on clinical history and coronary arteriography, controls with nonischemic chest pain who underwent coronary arteriography, and age-matched controls and normal hospital employees. In 16 patients with diagnosis of AMI, LTE4 excretion on admission (331 +/- 99 pg/mg creatinine sulfate; mean +/- SEM) was considerably higher than that measured on day 3 (195 +/- 59 pg/mg creatinine sulfate). In a subgroup of seven subjects treated with rt-PA resulting in early reperfusion, day 1 excretion was similar (215 +/- 50 pg/mg) but had significantly declined by day 3 (65 +/- 16 pg/mg; p less than 0.01). Urinary LTE4 excretion at admission for chest pain was also elevated in 14 patients having unstable angina (UA; 370 +/- 125 pg LTE4/mg creatinine sulfate). This had declined significantly (p less than 0.05) by day 3 (at which time chest pain had resolved) to 94 +/- 31 pg/mg creatinine sulfate, an excretion rate comparable with that measured in eight similarly aged subjects (64 +/- 12 pg/mg creatinine). CONCLUSIONS: This study suggests that peptide leukotrienes are released during episodes of myocardial ischemia and provides clinical evidence for involvement of their biosynthetic enzyme, 5-lipoxygenase, during and after acute myocardial infarction and unstable angina attacks. Thus, potent and specific orally active leukotriene biosynthesis inhibitors may have therapeutic potential in limiting myocardial damage and functional abnormalities after acute ischemia.

Persistent generation of peptido leukotrienes in patients with the adult respiratory distress syndrome.

The time course of leukotriene generation in the adult respiratory distress syndrome (ARDS) was investigated by measurement of urinary leukotriene E4 (LTE4) excretion, the major urinary LT metabolite in humans. Sequential measurements were made in nine subjects entered into the study within 48 h of the onset of ARDS, defined by an arterial/alveolar PO2 ratio of less than 0.3 and radiographic evidence of diffuse bilateral pulmonary edema. Initial urinary LTE4 excretion was significantly elevated (1.250 +/- 0.050 ng/mg creatinine sulphate; n = 7) compared with a non-ARDS postoperative group (0.254 +/- 0.114 ng/mg; n = 5) and normal control subjects (0.035 +/- 0.010 ng/mg; n = 12). LTE4 excretion in the first 24 h was estimated to be 6.9 micrograms, representing a release of 0.1 micrograms/kg/h of peptido leukotrienes into the bloodstream. These values were physiologically important based on a comparison with the increased urinary LTE4 excretion observed after antigen-induced bronchoconstriction in allergic asthmatics (baseline LTE4, 0.06 +/- 0.04 ng/mg; postantigen, 0.56 +/- 0.14 ng/mg; 0.17 micrograms LTE4/24 h; n = 8). In subjects with ARDS, this pathologic LTE4 excretion persisted during a subsequent 5-day study period. Leukotriene E4 excretion was associated with persistent abnormalities in gas exchange, pulmonary edema, and lung compliance, suggesting an important role for peptido leukotrienes in the pathophysiology of ARDS.

Measurement of urinary leukotrienes by reversed-phase liquid chromatography and radioimmunoassay.

Leukotriene (LT) E4, an important LT metabolite appearing in urine, can be rapidly separated from normal and pathological urines by automated reversed-phase HPLC after a simple sample-processing. The recoveries of LTE4 afforded by this system (86.4 +/- 6.5%, mean +/- SEM for 60 ng/L, 85.4 +/- 0.3% for 200 ng/L) are superior to those obtained by a manual extraction method. Consistency of results is similar. Highly reproducible retention times combined with a radioimmunoassay allow one to identify (based on co-elution) and quantify as little as 8 ng/L LTE4 in a 10-mL urine sample. LTE4 concentrations in urine from healthy persons approach this value (17 +/- 5 ng/L), whereas samples from patients with cardiac ischemia show a wider range of concentrations (8 to 388 ng/L), up to 50 times the detection limit. Thus this method is applicable to the noninvasive investigation of leukotriene involvement in a wide range of ischemic, inflammatory, and hypersensitive conditions.