Unusual features of intermediate septal bypass tracts.

INTRODUCTION: Intermediate septal (IS) AV bypass tracts, located along the tricuspid annulus between the His bundle and coronary sinus os, lie in close proximity to the AV node. Surgical or catheter ablation of IS bypass tracts incurs increased risk for development of complete heart block. We report additional unusual features of some IS bypass tracts that distinguish them from typical bypass tracts in other anatomic regions. METHODS AND RESULTS: We analyzed a consecutive series of 150 patients with a history of Wolff-Parkinson-White syndrome and supraventricular tachycardia who underwent ablation of bypass tracts. We studied the incidence and characteristics of AV conduction of IS bypass tracts compared with bypass tracts in other locations. Of the 150 patients in the study, 21 had an IS bypass tract (all had anterograde AV conduction). Ten (48%) of these 21 IS bypass tracts demonstrated anterograde decremental properties with atrial pacing versus 3 (2%) of 129 non-IS bypass tracts (P < 0.001). During ablation, a change in delta wave morphology before total loss of conduction in the IS bypass tract also occurred in 3 (14%) of 21 IS bypass tracts versus 0 of 129 non-IS bypass tracts (P = 0.0004). During ablation, a change in P wave to delta wave interval occurred in 4 (19%) of 21 IS bypass tracts versus 0 of 129 non-IS bypass tracts (P < 0.0001). One IS patient exhibited retrograde Wenckebach block in the bypass tract, and two IS patients showed loss of retrograde bypass tract conduction after ablation attempts that first changed the delta wave morphology. No non-IS patient had these features (P < 0.0001 for each comparison). CONCLUSION: Some IS bypass tracts have unusual properties that distinguish them from bypass tracts in other locations, perhaps due to the presence of multiple ventricular insertions of the bypass tract. It is possible that some cases represent true "nodoventricular" pathways.

Cardiac sympathetic denervation after transmyocardial laser revascularization.

BACKGROUND: Transmyocardial laser revascularization (TMR) has been shown to improve refractory angina not amenable to conventional coronary interventions. However, the mechanism of action remains controversial, because improved myocardial perfusion has not been consistently demonstrated. We hypothesized that TMR relieves angina by causing myocardial sympathetic denervation. METHODS AND RESULTS: PET imaging of resting and stress myocardial perfusion with [13N]ammonia (NH3) and of sympathetic innervation with [11C]hydroxyephedrine (HED) was performed before and after TMR in 8 patients with class IV angina ineligible for CABG or PTCA. A mean of 50+/-11 channels were created in the left ventricle (LV) with a holmium:YAG laser. A semiautomated program was used to determine NH3 uptake and HED retention in the LV. Perfusion and innervation defects were defined as the percentage of LV with tracer uptake or retention >2 SD below normal mean values. All patients experienced improvement in their angina by 2.4+/-0.5 angina classes after surgery, P=0.008. Sympathetic innervation defects exceeded resting perfusion defects in all patients before TMR (34.6+/-27.3% for HED versus 9.4+/-10.8% for NH3, P=0.008). TMR did not significantly affect resting or stress myocardial perfusion but increased the extent of sympathetic denervation in 6 of 8 patients by 27.5+/-15.9%, P=0.03. In the remaining 2 patients, both sympathetic denervation and stress perfusion defects decreased after surgery. CONCLUSIONS: TMR causes decreased myocardial HED uptake in most patients without significant change in resting or stress myocardial perfusion, suggesting that the improvement in angina may be at least in part due to sympathetic denervation.

Radiofrequency catheter ablation for postinfarct ventricular tachycardia.

Catheter mapping and radiofrequency ablation of postinfarct sustained ventricular tachycardia (VT) remain one of the greatest challenges for the electrophysiologist. Although there were no major breakthroughs during the past year, several refinements and clarifications of existing mapping criteria were published. In addition, initial reports appeared describing new mapping systems and ablation technologies that may significantly impact the way ablation studies are performed as well as the way in which they affect success rates. Uncertainties remain as to how effective catheter ablation will be as a longterm cure for this type of VT. For the foreseeable future, catheter ablation in postinfarct VT will remain adjunctive rather than primary therapy.

The value of red cell distribution width in the diagnosis of anaemia in children.

The red cell distribution width index (RDW) was determined in 103 normal children, 69 iron-deficient (ID) patients, 73 with the thalassaemia trait, and 71 with other haemoglobinopathies. Elevated RDW values were found in anaemic patients, the highest values in ID anaemia, sickle thalassaemia, sickle cell anaemia, and beta-thalassaemia trait in decreasing order. The normal RDW in children was 13.2 +/- 0.9 and an elevated RDW reflects active erythropoiesis. The RDW was elevated and the MCV low in all 69 patients with ID anaemia. The RDW was also elevated in 11/13 children with sickle cell anaemia, in 25/29 patients with sickle cell-thalassaemia, and in all patients with thalassaemia major. The ID anaemia could be differentiated from the thalassaemia trait by the markedly elevated RDW in ID anaemia (mean = 20.7 +/- 3.2) and the mildly elevated RDW (mean 15.4 +/- 1.4) in thalassaemia trait. The RDW index discriminated better than Mentzer's index, discriminant function or the Shine Lal index. Thus the RDW is a good indicator of anisocytosis, and a good screening index especially for ID anaemia and the thalassaemia trait.

Patterns of hepatomegaly in Jordanians: a prospective study of 800 cases.

Eight hundred Jordanians with liver enlargement were studied: 369 (46%) were males and 431 (54%) females. Ages ranged between 13 and 85 years, with a mean of 47.4%: 766 cases demonstrated a single pathological process while 34 cases showed two or more processes. The most significant findings were: congestion secondary to cardiac failure in 323 cases (38.5%); inflammatory and parasitic processes in 192 cases (22.9%), including acute hepatitis (81 cases), hydatid cyst (63 cases), chronic hepatitis (27 cases), liver abscess (19 cases), brucellosis (one case) and malaria (one case); malignancy in 164 cases (19.6%); liver cirrhosis in 80 cases (9.5%); fatty metamorphosis in 47 cases (5.6%); metabolic and genetic disease in 11 cases (1.3%); miscellaneous conditions in nine cases (1.1%); and 15 apparently normal individuals (1.8%). Cardiac failure was the most frequent cause of hepatomegaly in this sample of Jordanians. Inflammatory processes were the second major cause, followed by malignancy and cirrhosis of the liver.