Ahmed Adlan | The University of Birmingham (original) (raw)

Papers by Ahmed Adlan

The FASEB Journal, 2014

Administration of the muscarinic cholinergic receptor blocker glycopyrrolate reportedly attenuate... more Administration of the muscarinic cholinergic receptor blocker glycopyrrolate reportedly attenuates the exercise-induced increase in middle cerebral artery mean blood velocity. We sought to determine the cholinergic contribution to blood flow in the internal carotid artery (ICA; duplex Doppler ultrasound) during low (42±9 Watts; mean±SE) and moderate (110±11 Watts) intensity leg cycling in seven young male subjects (21±1 yr). Mean arterial pressure (MAP) and heart rate (HR; ECG) were continuously monitored. Stroke volume (SV) was determined offline using Modelflow and cardiac output calculated (CO=HR×SV). Exercise trials were conducted under control (no drug) conditions and after cholinergic blockade by administration of glycopyrrolate. Cholinergic blockade increased resting CO (6.8±0.4 to 8.7±0.5 L/min; P<0.05) and MAP (79±2 to 89±3 mmHg), while the responses to exercise were similar. ICA blood flow increased similarly from rest during low and moderate intensity exercise under control (271±34, 333±27 and ...

The FASEB Journal, 2014

We sought to investigate whether device guided slow deep breathing (SDB; RESPeRATE©) influences m... more We sought to investigate whether device guided slow deep breathing (SDB; RESPeRATE©) influences muscle sympathetic nerve activity (MSNA) and spontaneous baroreflex sensitivity in young healthy individuals. Following a 10 min supine baseline period, 9 men (29±7 years, body mass index 24±2 kg/m2; mean±SD) undertook 10 min of SDB while respiratory frequency (strain gauge pneumobelt), partial pressure of end-tidal carbon dioxide (PETCO2), blood pressure (BP; finger photoplethymography), heart rate (HR; ECG) and MSNA (microneurography) were continuously monitored. Indices of arterial baroreflex control of the heart (sequence technique) and MSNA burst incidence were calculated. Respiratory rate was reduced from 12±2 to 6.2±0.7 breaths/min (P<0.001) during SDB, while PETCO2 (P=0.50), and mean BP (P=0.40) were unchanged. SDB significantly reduced MSNA burst incidence (i.e., percentage of cardiac cycles associated with a MSNA burst) from 25 (20-38) to 20 (18-33) (median and interquartile range; P=0.04). Neither ca...

The FASEB Journal, 2014

The influence of device-guided slow deep breathing (SDB; RESPeRATE) on arterial baroreflex contr... more The influence of device-guided slow deep breathing (SDB; RESPeRATE) on arterial baroreflex control of the heart and muscle sympathetic nerve activity (MSNA) in essential hypertension patients remains unclear. To address this, respiratory rate, partial pressure of end-tidal carbon dioxide (PETCO2), MSNA (microneurography), heart rate (HR) and blood pressure (BP: Finometer) were monitored in 8 hypertensive patients (55±14 years, BMI 28±3 kg/m2, 152±26/71±11 mmHg [systolic/diastolic BP], duration of hypertension 6.4±6.7 years; mean±SD) during 10 min of normal breathing and 10 min of SDB. Cardiac baroreflex sensitivity (sequence technique) and spontaneous arterial baroreflex control of MSNA burst incidence were calculated offline. As expected, SDB decreased respiratory rate (13±4 to 6±1 breath/min, P=0.001), whereas PETCO2 (P=0.22), and mean BP (98±14 to 97±13 mmHg, P=0.11) were unchanged. MSNA burst incidence tended to fall during SDB (median with interquartile range from 46 [34-56] t...

Heart, 2020

A patient (aged mid-70s) was admitted following 4 days of chest pain and breathlessness. Investig... more A patient (aged mid-70s) was admitted following 4 days of chest pain and breathlessness. Investigations suggested a completed transmural anterior myocardial infarction (MI): ECG revealed anterior ST-elevation with anteroseptal Q waves (figure 1A); elevated troponin I (6.98 µg/L, normal range <0.1 µg/L); echocardiography demonstrated severe left ventricular systolic dysfunction with anteroseptal akinesia; and chest radiograph demonstrated pulmonary congestion. Treatment received included intravenous furosemide and standard secondary prevention medications including bisoprolol 2.5 mg once daily (initiated 48 hours after admission). Coronary angiography, on day 7, demonstrated severe stenoses in the mid-left anterior descending (LAD) and proximal obtuse marginal (OM) arteries (figure 1B). Figure 1 (A) Admission ECG, (B) coronary angiography, (C) ECG morphology of unifocal premature ventricular complex and (D) telemetry recording showing polymorphic ventricular tachycardia and initia...

Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia and is associated with inc... more Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia and is associated with increased morbidity and mortality due to stroke and thrombo-embolism. In patients with AF, strokes are usually more severe, resulting in longer hospital stays, worse disability and considerable healthcare costs. The prevention of stroke therefore is crucial in the management of AF. Stroke risk stratification tools can be used to determine patients at higher risk of stroke, and if no contraindications are present oral anticoagulation (OAC) therapy can be initiated. Despite the strong evidence for the benefit of OAC in stroke prevention in patients with AF, the use of thromboprophylaxis remains inadequate. The key measures to prevent stroke in patients with AF include: adequate stroke risk assessment and thrombo-prophylaxis; prompt initiation of OAC and avoidance of interruptions; earlier detection of AF; and education to overcome the under-usage of OAC in elderly patients.

Rheumatoid arthritis (RA) is a chronic inflammatory condition with poorly understood pathophysiol... more Rheumatoid arthritis (RA) is a chronic inflammatory condition with poorly understood pathophysiology and increased cardiovascular risk. The mechanisms for increased cardiovascular risk are not fully known, however one novel mechanism explored in this thesis is autonomic nervous system (ANS) dysfunction. The thesis comprises of: a systematic literature review; two case-control studies (n=30 RA patients, n=34 controls; a longitudinal case-study (n=1 RA patient); a cohort study (n=112 RA patients); and a randomised placebo controlled crossover study (n=10 healthy controls). The work presented in this thesis demonstrates that ANS dysfunction is prevalent in ~60 % of RA patients and characterised by heightened sympathetic outflow to the peripheral vasculature (determined by muscle sympathetic nerve activity using microneurography), depressed baroreflex control of heart rate (determined using the modified Oxford technique), depressed heart rate variability and heightened vascular response...

The FASEB Journal, 2014

Rheumatoid arthritis (RA) is an inflammatory disorder associated with increased cardiovascular mo... more Rheumatoid arthritis (RA) is an inflammatory disorder associated with increased cardiovascular mortality. We sought to determine whether muscle sympathetic nerve activity (MSNA) is heightened, and cardiac baroreflex sensitivity (cBRS) is reduced in patients with RA. Whilst resting supine, blood pressure (BP; Portapres), heart rate (HR; ECG) and MSNA (microneurography) were continuously monitored in 7 chronic RA patients (5 men, 56±4 yr, 28±1 kg/m²; mean±SE), 7 healthy controls (HC: 5 men, 52±5 yr, 26±1 kg/m²) and 7 patients with hypertension as ‘disease’ controls (DC: 5 men, 54±5 yr, 28±1 kg/m²). MSNA burst frequency and spontaneous cardiac baroreflex sensitivity (sequence technique, systolic BP-RR interval) were determined. Mean BP (p=0.001) and HR (p=0.014) were lower in HC group (88±5 mmHg, 55±2 bpm) than RA patients (106±2 mmHg, 70±3 bpm) and the DC group (116±6 mmHg, 63±4 bpm). MSNA burst frequency tended to be higher in RA patients and the DC group (34±4, 37±3 and 26±3 bursts/min in RA, DC, HC; P=0....

Journal of Interventional Cardiac Electrophysiology, 2021

Background Catheter ablation of ventricular tachycardia (VT) is associated with potential major c... more Background Catheter ablation of ventricular tachycardia (VT) is associated with potential major complications, including mortality. The risk of acute complications in patients with ischaemic cardiomyopathy (ICM) and non-ischaemic cardiomyopathy (NICM) has not been systematically evaluated. Methods PubMed was searched for studies of catheter ablation of VT published between September 2009 and September 2019. Pre-specified primary outcomes were (1) rate of major acute complications, including death, and (2) mortality rate. Results A total of 7395 references were evaluated for relevance. From this, 50 studies with a total of 3833 patients undergoing 4319 VT ablation procedures fulfilled the inclusion criteria (mean age 59 years; male 82%; 2363 [62%] ICM; 1470 [38%] NICM). The overall major complication rate in ICM cohorts was 9.4% (95% CI, 8.1–10.7) and NICM cohorts was 7.1% (95% CI, 6.0–8.3). Reported complication rates were highly variable between studies (ICM I2 = 90%; NICM I2 = 89%...

Journal of Arrhythmia, 2020

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-... more This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

British Journal of Cardiology, 2020

Journal of Interventional Cardiac Electrophysiology, 2019

Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entra... more Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entrant ventricular tachycardia (VT) is key for effective mapping and ablation strategies. Understanding wavefront propagation is driving advances in high-density (HD) mapping. The newly developed Advisor™ HD Grid Mapping Catheter (HD GRID) has equidistant spacing of 16, 1 mm electrodes in a 4 × 4 3 mm interspaced arrangement allowing bipolar recordings along and uniquely across the splines (orthogonal vector) to facilitate substrate mapping in a WAVE configuration (WAVE). The purpose of this study was to determine the relative importance of the WAVE configuration compared to the STANDARD linear-only bipolar configuration (STANDARD) in defining VT substrate. Thirteen patients underwent VT ablation at our institution. In all cases, a substrate map was constructed with the HD GRID in the WAVE configuration (conWAVE) to guide ablation strategy. At the end of the procedure, the voltage map was remapped in the STANDARD configuration (conSTANDARD) using the turbo-map function. Detailed post-hoc analysis of the WAVE and STANDARD maps was performed blinded to the configuration. Quantification of total scar area, BZ and dense scar area with assessment of conduction channels (CC) was performed. The substrate maps conSTANDARD vs conWAVE showed statistically significant differences in the total scar area (56 ± 32 cm2 vs 51 ± 30 cm2; p = 0.035), dense scar area (36 ± 25 cm2 vs 29 ± 22 cm2; p = 0.002) and number of CC (3.3 ± 1.6 vs 4.8 ± 2.5; p = 0.026). conWAVE collected more points than the conSTANDARD settings (p = 0.001); however, it used fewer points in map construction (p = 0.023). The multipolar Advisor™ HD Grid Mapping Catheter in conWAVE provides more efficient point acquisition and greater VT substrate definition of the borderzone particularly at the low-voltage range compared to conSTANDARD. This greater resolution within the low-voltage range facilitated CC definition and quantification within the scar, which is essential in guiding the ablation strategy.

Journal of Cardiovascular Electrophysiology, 2019

The Journal of Physiology, 2018

Where a licence is displayed above, please note the terms and conditions of the licence govern yo... more Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.

The Journal of Rheumatology, 2018

The FASEB Journal, 2014

Administration of the muscarinic cholinergic receptor blocker glycopyrrolate reportedly attenuate... more Administration of the muscarinic cholinergic receptor blocker glycopyrrolate reportedly attenuates the exercise-induced increase in middle cerebral artery mean blood velocity. We sought to determine the cholinergic contribution to blood flow in the internal carotid artery (ICA; duplex Doppler ultrasound) during low (42±9 Watts; mean±SE) and moderate (110±11 Watts) intensity leg cycling in seven young male subjects (21±1 yr). Mean arterial pressure (MAP) and heart rate (HR; ECG) were continuously monitored. Stroke volume (SV) was determined offline using Modelflow and cardiac output calculated (CO=HR×SV). Exercise trials were conducted under control (no drug) conditions and after cholinergic blockade by administration of glycopyrrolate. Cholinergic blockade increased resting CO (6.8±0.4 to 8.7±0.5 L/min; P<0.05) and MAP (79±2 to 89±3 mmHg), while the responses to exercise were similar. ICA blood flow increased similarly from rest during low and moderate intensity exercise under control (271±34, 333±27 and ...

The FASEB Journal, 2014

We sought to investigate whether device guided slow deep breathing (SDB; RESPeRATE©) influences m... more We sought to investigate whether device guided slow deep breathing (SDB; RESPeRATE©) influences muscle sympathetic nerve activity (MSNA) and spontaneous baroreflex sensitivity in young healthy individuals. Following a 10 min supine baseline period, 9 men (29±7 years, body mass index 24±2 kg/m2; mean±SD) undertook 10 min of SDB while respiratory frequency (strain gauge pneumobelt), partial pressure of end-tidal carbon dioxide (PETCO2), blood pressure (BP; finger photoplethymography), heart rate (HR; ECG) and MSNA (microneurography) were continuously monitored. Indices of arterial baroreflex control of the heart (sequence technique) and MSNA burst incidence were calculated. Respiratory rate was reduced from 12±2 to 6.2±0.7 breaths/min (P<0.001) during SDB, while PETCO2 (P=0.50), and mean BP (P=0.40) were unchanged. SDB significantly reduced MSNA burst incidence (i.e., percentage of cardiac cycles associated with a MSNA burst) from 25 (20-38) to 20 (18-33) (median and interquartile range; P=0.04). Neither ca...

The FASEB Journal, 2014

The influence of device-guided slow deep breathing (SDB; RESPeRATE) on arterial baroreflex contr... more The influence of device-guided slow deep breathing (SDB; RESPeRATE) on arterial baroreflex control of the heart and muscle sympathetic nerve activity (MSNA) in essential hypertension patients remains unclear. To address this, respiratory rate, partial pressure of end-tidal carbon dioxide (PETCO2), MSNA (microneurography), heart rate (HR) and blood pressure (BP: Finometer) were monitored in 8 hypertensive patients (55±14 years, BMI 28±3 kg/m2, 152±26/71±11 mmHg [systolic/diastolic BP], duration of hypertension 6.4±6.7 years; mean±SD) during 10 min of normal breathing and 10 min of SDB. Cardiac baroreflex sensitivity (sequence technique) and spontaneous arterial baroreflex control of MSNA burst incidence were calculated offline. As expected, SDB decreased respiratory rate (13±4 to 6±1 breath/min, P=0.001), whereas PETCO2 (P=0.22), and mean BP (98±14 to 97±13 mmHg, P=0.11) were unchanged. MSNA burst incidence tended to fall during SDB (median with interquartile range from 46 [34-56] t...

Heart, 2020

A patient (aged mid-70s) was admitted following 4 days of chest pain and breathlessness. Investig... more A patient (aged mid-70s) was admitted following 4 days of chest pain and breathlessness. Investigations suggested a completed transmural anterior myocardial infarction (MI): ECG revealed anterior ST-elevation with anteroseptal Q waves (figure 1A); elevated troponin I (6.98 µg/L, normal range <0.1 µg/L); echocardiography demonstrated severe left ventricular systolic dysfunction with anteroseptal akinesia; and chest radiograph demonstrated pulmonary congestion. Treatment received included intravenous furosemide and standard secondary prevention medications including bisoprolol 2.5 mg once daily (initiated 48 hours after admission). Coronary angiography, on day 7, demonstrated severe stenoses in the mid-left anterior descending (LAD) and proximal obtuse marginal (OM) arteries (figure 1B). Figure 1 (A) Admission ECG, (B) coronary angiography, (C) ECG morphology of unifocal premature ventricular complex and (D) telemetry recording showing polymorphic ventricular tachycardia and initia...

Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia and is associated with inc... more Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia and is associated with increased morbidity and mortality due to stroke and thrombo-embolism. In patients with AF, strokes are usually more severe, resulting in longer hospital stays, worse disability and considerable healthcare costs. The prevention of stroke therefore is crucial in the management of AF. Stroke risk stratification tools can be used to determine patients at higher risk of stroke, and if no contraindications are present oral anticoagulation (OAC) therapy can be initiated. Despite the strong evidence for the benefit of OAC in stroke prevention in patients with AF, the use of thromboprophylaxis remains inadequate. The key measures to prevent stroke in patients with AF include: adequate stroke risk assessment and thrombo-prophylaxis; prompt initiation of OAC and avoidance of interruptions; earlier detection of AF; and education to overcome the under-usage of OAC in elderly patients.

Rheumatoid arthritis (RA) is a chronic inflammatory condition with poorly understood pathophysiol... more Rheumatoid arthritis (RA) is a chronic inflammatory condition with poorly understood pathophysiology and increased cardiovascular risk. The mechanisms for increased cardiovascular risk are not fully known, however one novel mechanism explored in this thesis is autonomic nervous system (ANS) dysfunction. The thesis comprises of: a systematic literature review; two case-control studies (n=30 RA patients, n=34 controls; a longitudinal case-study (n=1 RA patient); a cohort study (n=112 RA patients); and a randomised placebo controlled crossover study (n=10 healthy controls). The work presented in this thesis demonstrates that ANS dysfunction is prevalent in ~60 % of RA patients and characterised by heightened sympathetic outflow to the peripheral vasculature (determined by muscle sympathetic nerve activity using microneurography), depressed baroreflex control of heart rate (determined using the modified Oxford technique), depressed heart rate variability and heightened vascular response...

The FASEB Journal, 2014

Rheumatoid arthritis (RA) is an inflammatory disorder associated with increased cardiovascular mo... more Rheumatoid arthritis (RA) is an inflammatory disorder associated with increased cardiovascular mortality. We sought to determine whether muscle sympathetic nerve activity (MSNA) is heightened, and cardiac baroreflex sensitivity (cBRS) is reduced in patients with RA. Whilst resting supine, blood pressure (BP; Portapres), heart rate (HR; ECG) and MSNA (microneurography) were continuously monitored in 7 chronic RA patients (5 men, 56±4 yr, 28±1 kg/m²; mean±SE), 7 healthy controls (HC: 5 men, 52±5 yr, 26±1 kg/m²) and 7 patients with hypertension as ‘disease’ controls (DC: 5 men, 54±5 yr, 28±1 kg/m²). MSNA burst frequency and spontaneous cardiac baroreflex sensitivity (sequence technique, systolic BP-RR interval) were determined. Mean BP (p=0.001) and HR (p=0.014) were lower in HC group (88±5 mmHg, 55±2 bpm) than RA patients (106±2 mmHg, 70±3 bpm) and the DC group (116±6 mmHg, 63±4 bpm). MSNA burst frequency tended to be higher in RA patients and the DC group (34±4, 37±3 and 26±3 bursts/min in RA, DC, HC; P=0....

Journal of Interventional Cardiac Electrophysiology, 2021

Background Catheter ablation of ventricular tachycardia (VT) is associated with potential major c... more Background Catheter ablation of ventricular tachycardia (VT) is associated with potential major complications, including mortality. The risk of acute complications in patients with ischaemic cardiomyopathy (ICM) and non-ischaemic cardiomyopathy (NICM) has not been systematically evaluated. Methods PubMed was searched for studies of catheter ablation of VT published between September 2009 and September 2019. Pre-specified primary outcomes were (1) rate of major acute complications, including death, and (2) mortality rate. Results A total of 7395 references were evaluated for relevance. From this, 50 studies with a total of 3833 patients undergoing 4319 VT ablation procedures fulfilled the inclusion criteria (mean age 59 years; male 82%; 2363 [62%] ICM; 1470 [38%] NICM). The overall major complication rate in ICM cohorts was 9.4% (95% CI, 8.1–10.7) and NICM cohorts was 7.1% (95% CI, 6.0–8.3). Reported complication rates were highly variable between studies (ICM I2 = 90%; NICM I2 = 89%...

Journal of Arrhythmia, 2020

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-... more This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

British Journal of Cardiology, 2020

Journal of Interventional Cardiac Electrophysiology, 2019

Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entra... more Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entrant ventricular tachycardia (VT) is key for effective mapping and ablation strategies. Understanding wavefront propagation is driving advances in high-density (HD) mapping. The newly developed Advisor™ HD Grid Mapping Catheter (HD GRID) has equidistant spacing of 16, 1 mm electrodes in a 4 × 4 3 mm interspaced arrangement allowing bipolar recordings along and uniquely across the splines (orthogonal vector) to facilitate substrate mapping in a WAVE configuration (WAVE). The purpose of this study was to determine the relative importance of the WAVE configuration compared to the STANDARD linear-only bipolar configuration (STANDARD) in defining VT substrate. Thirteen patients underwent VT ablation at our institution. In all cases, a substrate map was constructed with the HD GRID in the WAVE configuration (conWAVE) to guide ablation strategy. At the end of the procedure, the voltage map was remapped in the STANDARD configuration (conSTANDARD) using the turbo-map function. Detailed post-hoc analysis of the WAVE and STANDARD maps was performed blinded to the configuration. Quantification of total scar area, BZ and dense scar area with assessment of conduction channels (CC) was performed. The substrate maps conSTANDARD vs conWAVE showed statistically significant differences in the total scar area (56 ± 32 cm2 vs 51 ± 30 cm2; p = 0.035), dense scar area (36 ± 25 cm2 vs 29 ± 22 cm2; p = 0.002) and number of CC (3.3 ± 1.6 vs 4.8 ± 2.5; p = 0.026). conWAVE collected more points than the conSTANDARD settings (p = 0.001); however, it used fewer points in map construction (p = 0.023). The multipolar Advisor™ HD Grid Mapping Catheter in conWAVE provides more efficient point acquisition and greater VT substrate definition of the borderzone particularly at the low-voltage range compared to conSTANDARD. This greater resolution within the low-voltage range facilitated CC definition and quantification within the scar, which is essential in guiding the ablation strategy.

Journal of Cardiovascular Electrophysiology, 2019

The Journal of Physiology, 2018

Where a licence is displayed above, please note the terms and conditions of the licence govern yo... more Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.

The Journal of Rheumatology, 2018