[Morphological and functional diagnostics of coronary artery disease by computed tomography]. / Morphologische und funktionelle Diagnostik der koronaren Herzkrankheit mittels Computertomographie.

Computed tomography coronary angiography (cCTA) is a safe option for the noninvasive exclusion of significant coronary stenoses in patients with a low or moderate pretest probability for coronary artery disease (CAD). Furthermore, it also allows functional and morphological assessment of coronary stenoses. The European Society of Cardiology (ESC) guidelines on the diagnosis and management of chronic coronary syndrome published in 2019 have strengthened the importance of cCTA in this context and for this reason it has experienced a considerable upgrade. The determination of the Agatston score is a clinically established method for quantifying coronary calcification and influences the initiation of drug treatment. With technologies, such as the introduction of electrocardiography (ECG)-controlled dose modulation and iterative image reconstruction, cCTA can be performed with high image quality and low radiation exposure. Anatomic imaging of coronary stenoses alone is currently being augmented by innovative techniques, such as myocardial CT perfusion imaging or CT-fractional flow reserve (FFR) but the clinical value of these methods merits further investigation. The cCTA could therefore develop into a gatekeeper with respect to the indications for invasive coronary diagnostics and interventions.

Antinociceptive and anti-inflammatory effects of extract of Celtis iguanaea (Jacq.) Sargent leaves in mice.

The antinociceptive and anti-inflammatory activities of crude ethanolic extract of Celtis iguanaea leaves and their active fractions are reported. The oral treatment with crude ethanolic extract (CEE; 100, 300 or 1000 mg/Kg) inhibited the number of writhings in a dose-dependent manner. The intermediate dose also inhibited formalin-induced nociception in both phases. The oral treatment with dichloromethane fraction (DF; 9 mg/Kg) produced antinociceptive effect in both phases of formalin test; however, the treatment with ethyl acetate fraction (EAF; 16 mg/Kg) reduced pain only in the second phase of this test. The oral treatments with CEE (300 mg/Kg) or DF (9 mg/Kg) reduced the nociception induced by capsaicin and pre-treatment with naloxone did not change these effects. The oral administration of CEE (300 mg/Kg), DF (9 mg/Kg) or ethyl EAF (16 mg/Kg) reduced ear edema, leukocytes migration and myeloperoxidase activity. Furthermore, the oral treatment with CEE (300 mg/Kg) or EAF (16 mg/Kg) reduced the level of Tumor Necrosis Factor - Alpha (TNF-α) in the pleurisy test. In conclusion, the DF showed antinociceptive activity that involves the vanilloid system as well as anti-inflammatory effect and the EAF showed anti-inflammatory activity involving the reduction of TNF-α cytokine.

Circulatory efficiency in patients with severe aortic valve stenosis before and after aortic valve replacement.

BACKGROUND: Circulatory efficiency reflects the ratio between total left ventricular work and the work required for maintaining cardiovascular circulation. The effect of severe aortic valve stenosis (AS) and aortic valve replacement (AVR) on left ventricular/circulatory mechanical power and efficiency is not yet fully understood. We aimed to quantify left ventricular (LV) efficiency in patients with severe AS before and after surgical AVR. METHODS: Circulatory efficiency was computed from cardiovascular magnetic resonance (CMR) imaging derived volumetric data, echocardiographic and clinical data in patients with severe AS (n = 41) before and 4 months after AVR and in age and sex-matched healthy subjects (n = 10). RESULTS: In patients with AS circulatory efficiency was significantly decreased compared to healthy subjects (9 ± 3% vs 12 ± 2%; p = 0.004). There were significant negative correlations between circulatory efficiency and LV myocardial mass (r = - 0.591, p < 0.001), myocardial fibrosis volume (r = - 0.427, p = 0.015), end systolic volume (r = - 0.609, p < 0.001) and NT-proBNP (r = - 0.444, p = 0.009) and significant positive correlation between circulatory efficiency and LV ejection fraction (r = 0.704, p < 0.001). After AVR, circulatory efficiency increased significantly in the total cohort (9 ± 3 vs 13 ± 5%; p < 0.001). However, in 10/41 (24%) patients, circulatory efficiency remained below 10% after AVR and, thus, did not restore to normal values. These patients also showed less reduction in myocardial fibrosis volume compared to patients with restored circulatory efficiency after AVR. CONCLUSION: In our cohort, circulatory efficiency is reduced in patients with severe AS. In 76% of cases, AVR leads to normalization of circulatory efficiency. However, in 24% of patients, circulatory efficiency remained below normal values even after successful AVR. In these patients also less regression of myocardial fibrosis volume was seen. Trial Registration clinicaltrials.gov NCT03172338, June 1, 2017, retrospectively registered.

The role of non-invasive devices for the telemonitoring of heart failure patients.

Heart failure (HF) patients represent one of the most prevalent as well as one of the most fragile population encountered in the cardiology and internal medicine departments nowadays. Estimated to account for around 26 million people worldwide, diagnosed patients present a poor prognosis and quality of life with a clinical history accompanied by repeated hospital admissions caused by an exacerbation of their chronic condition. The frequent hospitalizations and the extended hospital stays mean an extremely high economic burden for healthcare institutions. Meanwhile, the number of chronically diseased and elderly patients is continuously rising, and a lack of specialized physicians is evident. To cope with this health emergency, more efficient strategies for patient management, more accurate diagnostic tools, and more efficient preventive plans are needed. In recent years, telemonitoring has been introduced as the potential answer to solve such needs. Different methodologies and devices have been progressively investigated for effective home monitoring of cardiologic patients. Invasive hemodynamic devices, such as CardioMEMS™, have been demonstrated to be reducing hospitalizations and mortality, but their use is however restricted to limited cases. The role of external non-invasive devices for remote patient monitoring, instead, is yet to be clarified. In this review, we summarized the most relevant studies and devices that, by utilizing non-invasive telemonitoring, demonstrated whether beneficial effects in the management of HF patients were effective.

Cardiovascular magnetic resonance-derived left ventricular mechanics-strain, cardiac power and end-systolic elastance under various inotropic states in swine.

BACKGROUND: Cardiovascular magnetic resonance (CMR) strain imaging is an established technique to quantify myocardial deformation. However, to what extent left ventricular (LV) systolic strain, and therefore LV mechanics, reflects classical hemodynamic parameters under various inotropic states is still not completely clear. Therefore, the aim of this study was to investigate the correlation of LV global strain parameters measured via CMR feature tracking (CMR-FT, based on conventional cine balanced steady state free precession (bSSFP) images) with hemodynamic parameters such as cardiac index (CI), cardiac power output (CPO) and end-systolic elastance (Ees) under various inotropic states. METHODS: Ten anaesthetized, healthy Landrace swine were acutely instrumented closed-chest and transported to the CMR facility for measurements. After baseline measurements, two steps were performed: (1) dobutamine-stress (Dobutamine) and (2) verapamil-induced cardiovascular depression (Verapamil). During each protocol, CMR images were acquired in the short axisand apical 2Ch, 3Ch and 4Ch views. MEDIS software was utilized to analyze global longitudinal (GLS), global circumferential (GCS), and global radial strain (GRS). RESULTS: Dobutamine significantly increased heart rate, CI, CPO and Ees, while Verapamil decreased them. Absolute values of GLS, GCS and GRS accordingly increased during Dobutamine infusion, while GLS and GCS decreased during Verapamil. Linear regression analysis showed a moderate correlation between GLS, GCS and LV hemodynamic parameters, while GRS correlated poorly. Indexing global strain parameters for indirect measures of afterload, such as mean aortic pressure or wall stress, significantly improved these correlations, with GLS indexed for wall stress reflecting LV contractility as the clinically widespread LV ejection fraction. CONCLUSION: GLS and GCS correlate accordingly with LV hemodynamics under various inotropic states in swine. Indexing strain parameters for indirect measures of afterload substantially improves this correlation, with GLS being as good as LV ejection fraction in reflecting LV contractility. CMR-FT-strain imaging may be a quick and promising tool to characterize LV hemodynamics in patients with varying degrees of LV dysfunction.

Estimation of total collagen volume: a T1 mapping versus histological comparison study in healthy Landrace pigs.

Right ventricular biopsy represents the gold standard for the assessment of myocardial fibrosis and collagen content. This invasive technique, however, is accompanied by perioperative complications and poor reproducibility. Extracellular volume (ECV) measured through cardiovascular magnetic resonance (CMR) has emerged as a valid surrogate method to assess fibrosis non-invasively. Nonetheless, ECV provides an overestimation of collagen concentration since it also considers interstitial space. Our study aims to investigate the feasibility of estimating total collagen volume (TCV) through CMR by comparing it with the TCV measured at histology. Seven healthy Landrace pigs were acutely instrumented closed-chest and transported to the MRI facility for measurements. For each protocol, CMR imaging at 3T was acquired. MEDIS software was used to analyze T1 mapping and ECV for both the left ventricular myocardium (LVmyo) and left ventricular septum (LVseptum). ECV was then used to estimate TCVCMR at LVmyo and LVseptum following previously published formulas. Tissues were prepared following an established protocol and stained with picrosirius red to analyze the TCVhisto in LVmyo and LVseptum. TCV measured at LVmyo and LVseptum with both histology (8 ± 5 ml and 7 ± 3 ml, respectively) and T1-Mapping (9 ± 5 ml and 8 ± 6 ml, respectively) did not show any regional differences. TCVhisto and TCVCMR showed a good level of data agreement by Bland-Altman analysis. Estimation of TCV through CMR may be a promising way to non-invasively assess myocardial collagen content and may be useful to track disease progression or treatment response.

Cardiovascular magnetic resonance feature tracking in pigs: a reproducibility and sample size calculation study.

Cardiovascular magnetic resonance feature tracking (CMR-FT) is a novel technique for non-invasive assessment of myocardial motion and deformation. Although CMR-FT is standardized in humans, literature on comparative analysis from animal models is scarce. In this study, we measured the reproducibility of global strain under various inotropic states and the sample size needed to test its relative changes in pigs. Ten anesthetized healthy Landrace pigs were investigated. After baseline (BL), two further steps were performed: (I) dobutamine-induced hyper-contractility (Dob) and (II) verapamil-induced hypocontractility (Ver). Global longitudinal (GLS), circumferential (GCS) and radial strain (GRS) were assessed. This study shows a good to excellent inter- and intra-observer reproducibility of CMR-FT in pigs under various inotropic states. The highest inter-observer reproducibility was observed for GLS at both BL (ICC 0.88) and Ver (ICC 0.79). According to the sample size calculation for GLS, a small number of animals could be used for future trials.

Níveis pressóricos de hipertensos e normotensos após sessão de fisioterapia em solo e hidroterapia / Blood pressure levels in hypertensive and normotensive individuals after physical therapy and hydrotherapy session

Introdução: A hipertensão arterial sistêmica (HAS) é um dos maiores problemas de saúde pública da atualidade. Objetivo: Comparar os níveis pressóricos de uma sessão de fisioterapia tanto em solo quanto em hidroterapia em pacientes normotensos e hipertensos. Método: Trata-se de um estudo documental que envolveu coleta de dados em prontuários de pacientes com e sem HAS, atendidos na Clínica Escola de Fisioterapia de uma instituição de ensino superior privada. Foi utilizada uma ficha padronizada pelos autores para coleta dos dados: idade, sexo, frequência cardíaca, pressão arterial sistólica (PAS) e diastólica (PAD) dos prontuários. Os protocolos de atendimento fisioterapêutico em solo e hidroterapia tiveram duração de 50 minutos. Foram aplicados testes t pareado e não pareado de Student para comparar as variáveis de desfecho. Consideraram se estatisticamente significativos valores de p de p<0,05. Resultados: Foram analisados dados de 31 pacientes, 10 no grupo hipertenso e 21 no grupo normotenso. Houve maior prevalência do sexo feminino (60%) entre os hipertensos e do sexo masculino (52%) entre os normotensos. Na comparação da pressão arterial antes e depois das sessões de fisioterapia em solo e hidroterapia, verificou-se que os hipertensos apresentaram PAS significativamente maior (p<0,0001), tanto antes quanto depois das intervenções, e apresentaram PAD significativamente maior (p=0,03) depois das intervenções fisioterapêuticas. Conclusão: Uma sessão de fisioterapia em solo e hidroterapia causou incremento da PAD apenas em pacientes hipertensos.

Introduction: Systemic arterial hypertension (SAH) is one of the biggest public health problems nowadays. Objective: To compare the blood pressure levels of a physical therapy session in both soil and hydrotherapy in normotensive and hypertensive patients. Method: This is a documentary study that involved data collection in medical records of patients with and without hypertension, attended at the Clinical School of Physical Therapy from a private higher education institution. A standardized form was used by the authors to collect data: age, gender, heart rate, systolic (SBP) and diastolic (DBP) blood pressure from medical records. The protocols of physical therapy in soil and hydrotherapy lasted 50 minutes. Paired and unpaired Student's t-tests were applied to compare outcome variables. P values <0.05 were considered statistically significant. Results: Data from 31 patients were analyzed, 10 in the hypertensive group and 21 in the normotensive group. There was a higher prevalence of females (60%) among hypertensive patients and males (52%) among normotensive individuals. When comparing blood pressure before and after the ground physiotherapy and hydrotherapy sessions, it was found that hypertensive patients had significantly higher SBP (p<0.0001) both before and after the interventions, and had significantly higher DBP (p=0,03) after physical therapy interventions. Conclusion: A session of ground physiotherapy and hydrotherapy caused DBP increase only in hypertensive patients.

Differences in the prognostic relevance of myocardial ischaemia and scar by cardiac magnetic resonance in patients with and without diabetes mellitus.

AIMS: To evaluate the prognostic significance of myocardial ischaemia and scar in patients with and without diabetes mellitus (DM) who undergo dobutamine stress cardiac magnetic resonance (DCMR) and late gadolinium enhancement (LGE) imaging for known and suspected coronary artery diseases (CADs). METHODS AND RESULTS: A total of 1969 consecutive patients [age 63 ± 12 years, 29% female, left ventricular ejection fraction = 59 ± 12%] referred for a cardiac magnetic resonance (CMR) examination including DCMR and LGE with the suspicion of CAD or progression of CAD in three tertiary cardiac centres were analysed. Cardiac death and nonfatal myocardial infarction (MI) were registered as hard cardiac events. Patients with a revascularization procedure within the first 3 months after CMR were censored at the time of 'early' revascularization. Patients were followed for 3.2 ± 1.5 years (median 2.9, interquartile range 2-4.3 years). In total, 90 (4.6%) cardiac deaths and MI were registered. Among them, 328 patients (16.6%) had diabetes. The proportion of dobutamine-induced wall motion abnormalities (DWMA) and LGE was higher in patients with DM when compared with those without DM (27 vs. 19% and 53.6 vs. 41.2%, respectively, P < 0.001 for both for proportions). Both DWMA and LGE were independent predictors of cardiac death and MI in patients without DM (HR for DWMA 8, CI 4.5-14.3, HR for LGE 2.1, CI 1.1-4.1) and with DM (HR for DWMA 8.6, CI 3.5-21, HR for LGE 4.5, CI 1.5-13.1). Tests for interaction showed that LGE more strongly influences prognosis in patients with than in those without DM (P = 0.03 for interaction), whereas the presence of DWMA is related to similarly poor outcomes in patients with and without DM (P = NS). CONCLUSION: Myocardial scar by LGE is a hallmark of markedly poorer outcome in patients with DM, while the presence of inducible myocardial ischaemia seems to be predictive both in patients with and without DM. Both markers surpass the predictive value of conventional atherogenic risk factors both in patients with and without DM.

Comparison of acquisition time and dose for late gadolinium enhancement imaging at 3.0 T in patients with chronic myocardial infarction using Gd-BOPTA.

OBJECTIVES: To compare contrast doses and acquisition times for late gadolinium enhancement (LGE) imaging at 3.0 T using gadobenate dimeglumine (Gd-BOPTA) in patients with chronic myocardial infarction. METHODS: Thirty-four patients with chronic myocardial infarction were randomised to 0.10, 0.15 and 0.20 mmol/kg of Gd-BOPTA. T1-weighted inversion recovery gradient echo sequences were performed at 5, 10, 15 and 20 min post-administration of contrast in a 3.0-T scanner. Scar-to-myocardium contrast-to-noise ratio (CNR), scar-to-blood CNR, scar size and image quality were assessed. RESULTS: Imaging at 5 min was associated with a lower scar-to-blood CNR in comparison to 10, 15 and 20 min at 0.10 mmol/kg, and in comparison to 15 and 20 min at 0.20 mmol/kg. At 0.10-mmol/kg, imaging at 5 min yielded smaller infarct sizes in comparison to 15 and 20 min. Finally, at 0.20-mmol/kg, imaging at 5 min was associated with poorer image quality in comparison to later times. CONCLUSIONS: In LGE imaging at 3.0 T, low doses of Gd-BOPTA perform equally well as higher doses. Early acquisition (5 min) is associated with lower infarct sizes and image quality. Studies with sufficient diagnostic quality can be obtained after 10 min using 0.10 mmol/kg Gd-BOPTA. KEY POINTS: Good performance of low Gd-BOPTA doses for LGE imaging at 3.0 T. Imaging at 5 min yields lower contrast, infarct sizes and image quality. Diagnostic quality can be obtained after 10 min using 0.10-mmol/kg Gd-BOPTA.

[PCSK9 as new target in hyperlipidemia treatment]. / PCSK9 als neues Target in der Therapie der Hypercholesterinämie.

Proprotein convertase subtilisin/kexin type 9 (PCSK 9) is a key regulator of cholesterol homeostasis acting via degradation of the low density lipoprotein (LDL) receptor. Loss of function PCSK 9 mutations result in very low LDL cholesterol serum levels and protection from cardiovascular disease whereas gain of function mutations increase serum LDL cholesterol. Based on in vitro and in vivo data antibodies targeting PCSK 9 have now emerged as a novel treatment option in patients with cardiovascular disease. This review briefly summarizes the biochemistry and function of PCSK9 and the results from recent phase II trials.

Value of additional myocardial perfusion imaging during dobutamine stress magnetic resonance for the assessment of intermediate coronary artery disease.

This study was performed to assess the role of additional myocardial perfusion imaging during high dose dobutamine/atropine stress magnetic resonance (DSMR-wall motion) for the evaluation of patients with intermediate (50-70%) coronary artery stenosis. Routine DSMR-wall motion was combined with perfusion imaging (DSMR-perfusion) in 174 consecutive patients with chest pain syndromes who were scheduled for a clinically indicated coronary angiography. When defining CAD as the presence of a ≥ 50% stenosis, the addition of perfusion imaging improved sensitivity (90 vs. 79%, P < 0.001) with a non-significant reduction in specificity (85 vs. 90%, P = 0.13) and an improvement in overall diagnostic accuracy (88 vs. 84%, P = 0.008). Adding perfusion imaging improved sensitivity in patients with intermediate stenosis (87 vs. 72%, P = 0.03), but not in patients with severe (≥70%) stenosis (93 vs. 84%, P = 0.06). In patients with severe stenosis specificity of DSMR-perfusion versus DSMR-wall motion decreased (61 vs 70%, P = 0.001) resulting in a lower overall accuracy (71 vs 74%, P = 0.03). Using a cutoff of ≥50% for the definition of CAD, sensitivity of DSMR-perfusion compared to DSMR-wall motion was significantly higher in patients with single vessel (88 vs. 77%, P = 0.03) and multi vessel disease (93 vs. 79%, P = 0.03), whereas no significant differences were found using a cutoff of ≥70% stenosis for the definition of CAD. The addition of perfusion imaging during DSMR-wall motion improved the sensitivity in patients with intermediate coronary artery stenosis. Overall diagnostic accuracy increased only when defining CAD as ≥50% stenosis. In patients with ≥70% stenosis DSMR-wall motion alone had higher accuracy due to more false-positive cases with DSMR-perfusion.

Dobutamine stress cardiovascular magnetic resonance at 3 Tesla.

PURPOSE: The assessment of inducible wall motion abnormalities during high-dose dobutamine-stress cardiovascular magnetic resonance (DCMR) is well established for the identification of myocardial ischemia at 1.5 Tesla. Its feasibility at higher field strengths has not been reported. The present study was performed to prospectively determine the feasibility and diagnostic accuracy of DCMR at 3 Tesla for depicting hemodynamically significant coronary artery stenosis (> or = 50% diameter stenosis) in patients with suspected or known coronary artery disease (CAD). MATERIALS AND METHODS: Thirty consecutive patients (6 women) (66 +/- 9.3 years) were scheduled for DCMR between January and May 2007 for detection of coronary artery disease. Patients were examined with a Philips Achieva 3 Tesla system (Philips Healthcare, Best, The Netherlands), using a spoiled gradient echo cine sequence. Technical parameters were: spatial resolution 2 x 2 x 8 mm3, 30 heart phases, spoiled gradient echo TR/TE: 4.5/2.6 msec, flip angle 15 degrees . Images were acquired at rest and stress in accordance with a standardized high-dose dobutamine-atropine protocol during short breath-holds in three short and three long-axis views. Dobutamine was administered using a standard protocol (10 microg increments every 3 minutes up to 40 microg dobutamine/kg body weight/minute plus atropine if required to reach target heart rate). The study protocol included administration of 0.1 mmol/kg/body weight Gd-DTPA before the cine images at rest were acquired to improve the image quality. The examination was terminated if new or worsening wall-motion abnormalities or chest pain occurred or when > 85% of age-predicted maximum heart rate was reached. Myocardial ischemia was defined as new onset of wall-motion abnormality in at least one segment. In addition, late gadolinium enhancement (LGE) was performed. Images were evaluated by two blinded readers. Diagnostic accuracy was determined with coronary angiography as the reference standard. Image quality and wall-motion at rest and maximum stress level were evaluated using a four-point scale. RESULTS: In 27 patients DCMR was performed successfully, no patient had to be excluded due to insufficient image quality. Twenty-two patients were examined by coronary angiography, which depicted significant stenosis in 68.2% of the patients. Patient-based sensitivity and specificity were 80.0% and 85.7% respectively and accuracy was 81.8%. Interobserver variability for assessment of wall motion abnormalities was 88% (kappa = 0.760; p < 0.0001). Negative and positive predictive values were 66.7% and 92.3%, respectively. No significant differences in average image quality at rest versus stress for short or long-axis cine images were found. CONCLUSION: High-dose DCMR at 3T is feasible and an accurate method to depict significant coronary artery stenosis in patients with suspected or known CAD.

[Cardiovascular MRT--replacement of diagnostic invasive coronary angiography?]. / Kardio-MRT. Ersatz für die diagnostische Koronarangiographie?

With cardiovascular magnetic resonance imaging (CMR), the necessity of invasive coronary angiography may be increasingly avoided. CMR provides information about the anatomy of the coronaries themselves (e.g. anomalies, aneurysm), functional information on myocardial blood flow (dobutamine-stress-MR, perfusion measurement) and detailed information on cell-mediated alterations (e.g. fibrosis, necrosis). However, visualization of distal coronary vessels and the small side branches is not yet adequate, so that complete replacement of invasive coronary angiography by CMR is not possible.

Primary fibrosarcoma of the liver infiltrating the right atrium of the heart.

A rare case of a primary fibrosarcoma of the liver infiltrating the right heart is described in a 72-year-old woman. The patient presented with a history of progressive dyspnea and ascites and her general condition was poor. Preoperative cardiac magnetic resonance (CMR) imaging revealed a large mass, which originated from the liver and had infiltrated the right atrium via the inferior vena cava. The patient underwent tumor resection yet died shortly afterwards. Histologically the mass was classified as a fibrosarcoma with positive immunostaining for vimentin. We report the CMR imaging characteristics in this uncommon case. Preoperative CMR proved to be useful for clinical decision making and the planning of surgery.

Calculation of individual cardiovascular risk in a primary prevention setting shows a high number of patients with a high risk score.

On occasion of the annual convention of the European Society of Cardiology, general awareness was used to stage an event to inform the public about cardiovascular risk and cardiovascular disease. After the measurement of blood pressure, HDL and total cholesterol and after answering questions on smoking and medication visitors received a printout showing their individual calculated cardiovascular event rate over the next ten years. For the calculation of the expected event rate, the algorithm of the Adult Treatment Panel III was used. Of the 43,500 visitors 1513 were screened, 651 male, 862 female. Of those screened in this primary prevention setting 143 male (22.07%) and 9 female (1.02%) had an expected cardiovascular event rate of 20% or more over the next ten years requiring immediate action according to the current guidelines. The calculated risk scores are considerably lower than would be expected in a representative sample from the population. This indicates that patients with a high cardiovascular risk possibly do not take part in unstructured primary screening events.

Luminescence quenching by DNA-bound viologens: effect of reactant identity on efficiency and dynamics of electron transfer in DNA.

Photoinduced electron transfer from two intercalating photoactive donors, Ru(phen)2dppz2+ and ethidium, to intercalating viologen acceptors of the N,N'-dialkyl-6-(2'-pyridiniumyl)phenanthridinium family has been investigated through steady-state and time-resolved luminescence quenching measurements. Efficient quenching of the emission from these donors bound to DNA is observed at low concentrations of acceptor (1-10 eq.), and in time-resolved emission experiments it is determined that electron transfer occurs on the nanosecond time scale. Furthermore, transient absorption measurements confirm that the quenching is the result of a charge-transfer process; upon photoreaction of intercalated Ru(phen)2dppz2+ with a viologen acceptor, an intermediate with spectral properties resembling the expected charge-separated pair is observed. The quenching yields and kinetics obtained with this quencher are in marked contrast to those observed with these same donors paired with Rh(phi)2bpy3+ as an acceptor. The differing efficiencies of electron transfer for these donor/acceptor pairs bound to DNA as compared to others previously described are discussed qualitatively in terms of the structural and electronic properties of the different reactants.