Cardiac resynchronization therapy in patients with heart failure and narrow QRS complexes (≤ 130 ms): role of speckle tracking echocardiography and different interventricular (VV) pacing intervals.

PURPOSE: Response to cardiac resynchronization therapy (CRT) in patients with heart failure with reduced ejection fraction (HFrEF) depends on the degree of correction of interventricular (VV) electromechanical dyssynchrony between the left and right ventricles (LV, RV). Wide (> 130 ms [ms]) QRS interval is used as a qualifying ECG parameter for CRT device implantation. In this study, we aimed to evaluate myocardial strain (S) and myocardial strain patterns (SP) and strain rate (SR) by speckle tracking echocardiography (STE) and mechanical characteristics at different VV intervals in acute settings and long-term outcome from "sequential LV-RV" pacing programming in patients with narrow (< 130 ms) and wide (> 130 ms) QRS complexes as a basis for extending CRT in select patients with narrow QRS. METHODS: From a previously established cohort of patients who had undergone CRT device implantation, we identified patients with narrow (< 130 ms) and wide (> 130 ms) QRS complexes, groups A and B respectively. In all patients, we assessed myocardial SP and SR by STE, and mechanical characteristics at VV intervals: "LV Off," "VV0," "VV60," and "RV Off" to provide "RV-only," "simultaneous BiV," "sequential LV-RV," and "LV-only" pacing in the acute settings, and subsequently long-term clinical outcomes with CRT devices programmed to VV60. We compared acute STE characteristics and long-term clinical outcomes between the groups. RESULTS: The study cohort comprised 271 patients (age 69.2 ± 10.3 years [mean ± SD], male-60%). Group A (n = 69) and group B (n = 202) were well matched for the clinical variables, including distribution of patients with ischemic versus non-ischemic cardiomyopathies. QRS width and left ventricular ejection fraction (LVEF) in groups A and B were 120.1 ± 12.3 ms and 152.1 ± 12.9 ms (p < 0.05), and 22.3 ± 9.4%, and 23.3 ± 10.2% (p = not significant [NS]). With VV0, VV60, and LV-only timings, corresponding LVEF rates in the acute settings were 31.45 ± 10.9%, 40.08 ± 8.3%, and 44.32 ± 7.98% (p < 0.01) in group A, and 38.94 ± 8.5%, 46.91 ± 7.33%, and 49.9 ± 8.94% (p < 0.01) in group B, and accounted for similar incremental percentage increase in LVEF compared to baseline in group A (43.2 ± 51.7%, 80.9 ± 61.4%, and 93.4 ± 65.6% respectively) and group B (67.3 ± 82.0%, 100.6 ± 94.3%, and 112.9 ± 95.7% respectively) (p = NS). Abnormal SP and SR were consistently observed with RV pacing that improved with VV60 and LV-only pacing in both groups. Strain scores at different VV timings were similar between the groups (p = NS). At 1-year follow-up, LVEF improved from 22.4 ± 8.0% to 39.8 ± 11.5% (p ≤ 0.001) for the total cohort with similar increments observed in both groups (p = NS). There were fewer NYHA III-IV class patients at 1 year in both groups. CONCLUSIONS: Comparable myocardial SP and SR characteristics and LVEF improvement with VV60 and LV-only pacing in the acute setting and long-term outcome of CRT by "sequential LV-RV" pacing seen in patients with both narrow and wide QRS duration suggest that CRT device implantation may be justified in select patients with HFrEF and narrow QRS duration (< 130 ms) who have demonstrable dyssynchrony and abnormal myocardial SP and SR characteristics.

Myocardial strain characteristics at different interventricular pacing timings: implications for device programming and long-term clinical outcomes in patients with cardiac resynchronisation therapy.

AIMS: Response to cardiac resynchronisation therapy (CRT) in patients with heart failure depends on the degree of correction of electromechanical dyssynchrony between the left and right ventricles (LV, RV). It is not known whether chronic programming of interventricular (VV) intervals based on characterisation of myocardial strain at different pacing intervals performed acutely would have better long-term clinical outcomes. We hence aimed to evaluate this relationship between speckle tracking strain patterns and rates at different VV intervals and long-term clinical outcomes of programmed VV pacing in patients with CRT in a prospective, longitudinal follow-up study. METHODS: We assessed echocardiographic effects, myocardial strain patterns and rates in acute settings at VV intervals; 'LV Off', 'VV0', 'VV60' and 'RV Off' to provide 'RV-only', 'simultaneous BiV', 'sequential LV-RV' and 'LV-only' pacing respectively in 338 patients (age, 67.5 ± 10.3 years; male, 70%) with CRT. Thereafter, devices were programmed chronically to VV60, and long-term clinical outcomes were assessed. RESULTS: With VV0, VV60 and LV only pacing, LVEF improved to 33.6 ± 12.3%, 40.0 ± 11.4% and 42.6 ± 11.2%, respectively, from 23.7 ± 10.2% at baseline (p < .001). Incremental improvement in strain occurred with VV0, VV60 and LV only pacing; greatest with LV only pacing. At 1 year, 23% patients had NYHA III-IV compared to 96% at baseline (p < .001). CONCLUSIONS: In patients with CRT, different VV timings show significant differences in acute myocardial strain patterns and rates, and LVEF. These changes are markedly favourable with LV-only and sequential LV-RV pacing, the latter with chronic programming also results in long-term clinical improvement.

Single site electronic spectroscopy of palladium chlorin in n-octane matrixes at 7K.

The high resolution, single site emission and absorption spectra of palladium chlorin (PdC) in n-octane matrixes at 7K are reported. The emission and Q and Soret band absorption regions were investigated. The vibrational frequencies of the ground and the lowest energy pipi* excited states were determined from luminescence and excitation spectra, respectively. The emission from PdC was entirely phosphorescence. The emission and Qy region spectra of the complex are similar, having intense, narrow origin bands followed by relatively weak but orderly vibrational structure. The Qx region of this metal chlorin does not have a clear origin and exhibits complex vibrational structure which increases in intensity going to higher energy. In the Soret region of PdC there is only a single intense, broad band.

Single site electronic spectroscopy of magnesium isobacteriochlorin in n-octane matrixes at 7 K.

The high resolution, single site emission and absorption spectra of magnesium isobacteriochlorin (MgiBC) in n-octane matrixes at 7 K are reported. Its emission and Q and Soret band absorption regions have been investigated. The vibrational frequencies of the ground and the lowest energy pipi* singlet excited states were determined from luminescence and excitation spectra, respectively. The emission from MgiBC at 7 K seems to be entirely fluorescence. The luminescence and Q(y) region spectra of the complex are similar, having intense, narrow origin bands followed by relatively weak, but orderly vibrational structure. The Q(x) region does not have a clear origin and exhibits complex vibrational structure that increases in intensity going to higher energy. In the Soret region the individual pipi* origins are clearly identifiable and some vibrational structure was also observed.

Single site electronic spectroscopy of free base octaethylporphyrin, octaethychlorin and their diacids in n-octane at 298K and 7K.

Single site fluorescence and absorption spectra of free base octaethylporphyrin, octaethylchlorin and their respective diacids in n-octane at 298 K and 7 K are reported. Vibrational frequencies associated with the ground and excited states were determined from the spectra. All of these moieties exhibit well defined and narrow spectral features, with the exception of the octaethylchlorin diacid; it gives broad spectral bands even at 7 K. Respective Q and B origins were also identified.

Phosphorescence spectra and triplet state lifetimes of palladium octaethylporphyrin, palladium octaethylchlorin and palladium 2,3-dimethyloctaethylisobacteriochlorin at 77 K.

The phosphorescence spectra and triplet state lifetimes of palladium octaethylporphyrin (PdOEP), palladium octaethylchlorin (PdOEC) and palladium 2,3-dimethyloctaethylisobacteriochlorin (PdOEiBC) in n-octane Shpolskii matrices at 77 K are reported. The lifetime and T(1)/S(0) origin energy of each complex are: PdOEP, 1.90+/-0.04 ms, 15162 cm(-1); PdOEC, 0.43+/-0.03 ms, 12547 cm(-1) and PdOEiBC, 0.59+/-0.03 ms, 12863 cm(-1).

Determination of the ground state, excited state and change in dipole moments of magnesium and zinc chlorin.

High-resolution Stark effect measurements on the S1 <-- S0 (pi pi*) origin of magnesium chlorin (MgCh) and zinc chlorin (ZnCh) in single crystals of n-octane at 4.2 K are reported. The corresponding change in dipole moment (absolute value(delta mu(ge))) associated with each transition was estimated to be 0.23 +/- 0.04 and 0.27 +/- 0.05 debye, respectively. Each molecule's orientation in the n-octane crystal was also determined. The change in dipole moment of MgCh was also found using solvatochromic shift data (absolute value(delta mu(ge))) = 0.33 +/- 0.08 debye). The ground state dipole moment (mu(g)) of MgCh was determined by dielectric constant measurement of MgCh/benzene solutions (mu(g) = 2.26 +/- 0.08 debye). These were combined to calculate the average excited state dipole moment of MgCh (mu(e) = 2.51 +/- 0.08 debye). The ground state dipole moment of ZnCh was also determined using solvatochromic shift data (mu(g) = 3.17 +/- 0.08 debye). This was combined with its measured absolute value(delta mu(ge)) to calculate the excited state dipole moment of ZnCh (mu(e) = 3.44 +/- 0.08 debye); the S1 <-- S0 (pi pi*) origin band of both complexes was red-shifted at room temperature as the polarity of the solvents was increased, which implies that delta mu(ge) is positive.

Planarity of metal chlorins in n-octane solution.

The geometry of porphyrins has been and continues to be a subject of vigorous research. In this work we investigated the planarity of a series of divalent metal chlorins in n-octane solutions: magnesium, zinc, copper, nickel, cobalt, manganese, tin, cadmium, strontium, lead and platinum. Room temperature electronic absorption spectra of these complexes are reported. We plotted the energy of each B band against its respective Qy origin band. Based on these results it was concluded that in these metal chlorins the configuration interaction between Qy and B states is essentially constant; the exception is the magnesium complex which deviates from the pattern produced by the other metal chlorins. This suggests that the magnesium ion is out of the plane of the chlorin skeleton; thus, it has C(S) symmetry while the other metal chlorins in this group retained C2v symmetry.