Publications

The genomes of 10 Aeromonas isolates identified and designated Aeromonas hydrophila WI, Riv3, and NF1 to NF4; A. dhakensis SSU; A. jandaei Riv2; and A. caviae NM22 and NM33 were sequenced and annotated. Isolates NF1 to NF4 were from a patient with necrotizing fasciitis (NF). Two environmental isolates (Riv2 and -3) were from the river water from which the NF patient acquired the infection. While isolates NF2 to NF4 were clonal, NF1 was genetically distinct. Outside the conserved core genomes of these 10 isolates, several unique genomic features were identified. The most virulent strains possessed one of the following four virulence factors or a combination of them: cytotoxic enterotoxin, exotoxin A, and type 3 and 6 secretion system effectors AexU and Hcp. In a septicemic-mouse model, SSU, NF1, and Riv2 were the most virulent, while NF2 was moderately virulent. These data correlated with high motility and biofilm formation by the former three isolates. Conversely, in a mouse model of intramuscular infection, NF2 was much more virulent than NF1. Isolates NF2, SSU, and Riv2 disseminated in high numbers from the muscular tissue to the visceral organs of mice, while NF1 reached the liver and spleen in relatively lower numbers on the basis of colony counting and tracking of bioluminescent strains in real time by in vivo imaging. Histopathologically, degeneration of myofibers with significant infiltration of polymorphonuclear cells due to the highly virulent strains was noted. Functional genomic analysis provided data that allowed us to correlate the highly infectious nature of Aeromonas pathotypes belonging to several different species with virulence signatures and their potential ability to cause NF.

BACKGROUND

Because the His bundle is intrinsic to the circuit in orthodromic reciprocating tachycardia and remote from that of atrioventricular nodal reentrant tachycardia (AVNRT), pacing the His bundle during supraventricular tachycardia (SVT) may be useful to distinguish these arrhythmias.

OBJECTIVE

The purpose of this study was to test the hypothesis that His overdrive pacing (HOP) would affect SVT immediately for orthodromic reciprocating tachycardia and in a delayed manner for AVNRT.

METHODS

Once SVT was induced, HOP was performed by pacing the His bundle 10-30 ms faster than the SVT cycle length. The maneuver was determined to have entered the tachycardia circuit when a nonfused His-capture beat advanced or delayed the subsequent atrial electrogram by ≥10 ms or when the tachycardia was terminated. The number of beats required to enter each tachycardia with HOP was recorded.

RESULTS

HOP was performed during 66 SVTs (26 atrioventricular reciprocating tachycardia [AVRT] and 40 AVNRT). Entry into the tachycardia within 1 beat had sensitivity of 92%, specificity of 92%, positive predictive value (PPV) of 89% and negative predictive value (NPV) of 95% to confirm the diagnosis of AVRT. A cutoff ≥3 beats to enter the circuit had sensitivity of 90%, specificity of 92%, PPV of 95% and NPV of 86% to confirm the diagnosis of AVNRT. HOP had sensitivity, specificity, PPV, and NPV of 100% for distinguishing septal AVRT from atypical AVNRT.

CONCLUSION

HOP during SVT is a novel technique for distinguishing orthodromic reciprocating tachycardia from AVNRT. It can reliably distinguish between these arrhythmias with high sensitivity and specificity.