Changes in cardiac output, rhythm regularity, and symptom severity after electrical cardioversion of atrial fibrillation.

OBJECTIVES: Symptoms in atrial fibrillation (AF) range from none to disabling. The physiological correlates of AF symptoms are not well characterized. This study investigated the association between physiological parameters and symptom severity before and after electrical cardioversion (EC) of AF. DESIGN: We studied 44 patients with persistent AF (age 66.2 ± 7.9 years, 16% females) 4 ± 2 days before and 5 ± 2 days after EC. Physiological parameters included cardiac output (CO; non-invasive inert gas rebreathing), heart rate (HR), RR variability and resting and ambulatory blood pressure (BP). Symptoms and quality of life (QoL) were assessed by the modified European Heart Rhythm Association score (mEHRA), the Atrial Fibrillation Effect on Quality of Life (AFEQT) and the Symptom Checklist for frequency and severity of symptoms (SCL). RESULTS: 28 of 44 patients were still in sinus rhythm (SR) at post EC evaluation. Those in SR had a decreased HR (-15.4 ± 13.1 bpm, p < 0.001), and an increased CO (+0.8 ± 0.7 L/min, p < 0.001) as compared to those with recurrent AF. Changes in CO after EC correlated with symptom improvement as scored by AFEQT (r = 0.36; p < 0.05), AFEQT symptoms subscore (r = 0.46; p < 0.01), SCL for frequency (r = 0.62; p < 0.01) and severity (r = 0.33; p < 0.05) of symptoms, and the mEHRA score (r = 0.50; p < 0.01). A decrease in RR variability showed similar correlations with these measures of symptom improvement. CONCLUSIONS: Improvements in symptoms and quality of life experienced by patients after electrical conversion of atrial fibrillation are correlated with an increase in CO and a decreased RR variability.

Testing a Patient-Specific In-Silico Model to Noninvasively Estimate Central Blood Pressure.

PURPOSE: To show some preliminary results about the possibility to exploit a cardiovascular mathematical model-made patient-specific by noninvasive data routinely measured during ordinary clinical examinations-in order to obtain sufficiently accurate central blood pressure (BP) estimates. METHODS: A closed-loop multiscale (0D and 1D) model of the cardiovascular system is made patient-specific by using as model inputs the individual mean heart rate and left-ventricular contraction time, weight, height, age, sex and mean/pulse brachial BPs. The resulting framework is used to determine central systolic, diastolic, mean and pulse pressures, which are compared with the beat-averaged invasive pressures of 12 patients aged 72 ± 6.61 years. RESULTS: Errors in central systolic, diastolic, mean and pulse pressures by the model are 4.26 ± 2.81, 5.86 ± 4.38, 4.98 ± 3.95 and 3.51±2.38 mmHg, respectively. CONCLUSION: The proposed modeling approach shows a good patient-specific response and appears to be potentially useful in clinical practice. However, this approach needs to be evaluated in a larger cohort of patients and could possibly be improved through more accurate oscillometric BP measurement methods.

Changes in 24-h ambulatory blood pressure following restoration of sinus rhythm in patients with atrial fibrillation.

OBJECTIVE: The interplay between atrial fibrillation and blood pressure (BP) is insufficiently studied. In symptomatic patients with persistent atrial fibrillation, electrical cardioversion (ECV) is often used to restore sinus rhythm. In this prospective study, we investigated how restoration of sinus rhythm affected 24-h ambulatory BP. METHODS: Ninety-eight patients with persistent atrial fibrillation were examined with 24-h ambulatory BP monitoring before and approximately a week after ECV. RESULTS: Sixty-two patients remained in sinus rhythm at the time of the second ambulatory BP monitoring (AF-SR group), whereas 36 patients had relapsed into atrial fibrillation (AF-AF group). In the AF-SR group, there was a significant increase in mean systolic 24-h BP (5.6 mmHg), a significant decrease in mean diastolic 24-h BP (-4.7 mmHg) and accordingly, a significant 25% (10.4 mmHg) increase in mean 24-h pulse pressure. CONCLUSION: These findings may reflect the haemodynamic conditions that are prevalent in atrial fibrillation, ambulatory BP measurement bias in atrial fibrillation or a combination of both factors. From a clinical standpoint, our results suggest that an increased attention to BP is needed when sinus rhythm is restored, as underlying hypertension may be masked by BP changes during atrial fibrillation. From a general standpoint, it may be speculated that BP, as indicated by the relatively large difference in pulse pressure, may be inherently different in atrial fibrillation and may therefore not be interpretable in the equivalent manner as BP in sinus rhythm.

The cholinergic anti-inflammatory pathway in resistant hypertension treated with renal denervation.

BACKGROUND: Renal denervation (RDN) reduces sympathetic tone and may alter the sympathetic-parasympathetic balance. The autonomic nervous system is partly a regulator of innate immunity via the cholinergic anti-inflammatory pathway (CAP) which inhibits inflammation via the vagus nerve. Placental Growth Factor (PlGF) influences a neuro-immunological pathway in the spleen which may contribute to hypertension. The aim of this study was to investigate if modulation of renal sympathetic nerve activity affects CAP in terms of cytokine release as well as levels of PlGF. METHODS: Ten patients treated with RDN (Medtronic Inc), were analyzed for TNF, IL-1b and IL-10 and Lipopolysaccharide (LPS)-stimulated cytokine release before RDN, 1 day after and at 3- and 6-months follow-up. Four patients who underwent elective coronary angiography served as disease controls (DC). RESULTS: Baseline TNF was significantly lower 1 day after RDN (p = 0.03). LPS-stimulated (0, 10 and 100 ng/mL) TNF and IL-1b were significantly lower 1 day after RDN (TNF p = 0.0009, p = 0.0009 and p = 0.001, IL-1b; p = 0.0001, p = 0.002 and p = 0.005). IL-10 was significantly higher one day after RDN (p = ns, p = 0.02 and p = 0.01). These differences however declined during follow up. A more marked TNF reduction was achieved with a cholinergic analogue, GTS-21, in LPS-stimulated whole blood as compared with samples without GTS-21. Cytokine levels in controls did not differ before and 1 day after coronary angiography. PlGF was significantly higher in RDN patients and DC compared with healthy controls but did not change during follow-up. CONCLUSION: RDN has an immediate effect on TNF in vivo and cytokine release ex vivo but seems to wane over time suggesting that current RDN techniques may not have long-lasting immunomodulatory effect. Repeated and extended stimulation of CAP in resistant hypertension by targeting neural circuits may be a potential therapeutic strategy for treatment of both hypertension and inflammation.

Systolic blood pressure increases in patients with atrial fibrillation regaining sinus rhythm after electrical cardioversion.

Direct current (DC) cardioversion is used to convert persistent atrial fibrillation (AF) to sinus rhythm (SR), but there is limited knowledge about how blood pressure (BP) is affected by conversion to SR. We sought to evaluate how BP changed in AF patients who converted to SR, compared to patients still in AF. In this retrospective registry analysis, we included a total of 487 patients, treated with DC cardioversion for persistent AF. We obtained data regarding medical history, medication, BP, and electrocardiogram the day before and 7 days after cardioversion. Systolic BP increased by 9 (±16) mm Hg (P < 0.01) and diastolic BP decreased by 3 (±9) mm Hg (P < 0.01) after conversion to SR. In the group of patients with restored SR, there was a 40% increase in the proportion of patients with a hypertensive BP level (≥140/90 mm Hg) after DC cardioversion compared to before. Patients still in AF had no significant change in BP. Systolic BP increases and diastolic BP slightly decreases when persistent AF is converted to SR. The underlying mechanisms explaining these findings are not known, but may involve either hemodynamic changes that occur when SR is restored, an underestimation of systolic BP in AF, or a combination of both. Our findings suggest that an increased attention to BP levels after a successful cardioversion is warranted.

High beat-to-beat blood pressure variability in atrial fibrillation compared to sinus rhythm.

PURPOSE: Atrial fibrillation (AF) is associated with an increased risk for cardiovascular morbidity and mortality, not entirely explained by thromboembolism. The underlying mechanisms for this association are largely unknown. Similarly, high blood pressure (BP) increases the risk for cardiovascular events. Despite this the interplay between AF and BP is insufficiently studied. The purpose of this study was to examine and quantify the beat-to-beat blood pressure variability in patients with AF in comparison to a control group of patients with sinus rhythm. MATERIALS AND METHODS: We studied 33 patients - 21 in atrial fibrillation and 12 in sinus rhythm - undergoing routine coronary angiography. Invasive blood pressure was recorded at three locations: radial artery, brachial artery and ascending aorta. Blood pressure variability, defined as average beat-to-beat blood pressure difference, was calculated for systolic and diastolic blood pressure at each site. RESULTS: We observed a significant difference (p < .001) in systolic and diastolic blood pressure variability between the atrial fibrillation and sinus rhythm groups at all locations. Systolic blood pressure variability roughly doubled in the atrial fibrillation group compared to the sinus rhythm group (4.9 and 2.4 mmHg respectively). Diastolic beat-to-beat blood pressure variability was approximately 6 times as high in the atrial fibrillation group compared to the sinus rhythm group (7.5 and 1.2 mmHg respectively). No significant difference in blood pressure variability was seen between measurement locations. CONCLUSIONS: Beat-to-beat blood pressure variability in patients with atrial fibrillation was substantially higher than in patients with sinus rhythm. Hemodynamic effects of this beat-to-beat variation in blood pressure may negatively affect vascular structure and function, which may contribute to the increased cardiovascular morbidity and mortality seen in patients with atrial fibrillation.