Pacing and Clinical Electrophysiology, Mar 1, 2004
ABSTRACT The traditional pulse generator implantation site lies subcutaneous on the fascia of the... more ABSTRACT The traditional pulse generator implantation site lies subcutaneous on the fascia of the pectoralis major muscle. This article describes a subpectoral pocket approach, which on anatomic investigation is actually "intrapectoral" and offers a much improved cosmetic result with the potential advantage of less erosion. In the authors' experience with over 1000 initial pacemaker implants and pulse generator replacements, the potential concerns of neurovascular and muscular damage have not been realized. There has been no pulse generator damage from the ribs, serious loculated hematomas, or unusual postoperative or chronic pain. From experience with pulse generator recalls, the replacement procedure has not been significantly more difficult than with the subcutaneous approach. The intrapectoral approach has now become the authors' routine in patients without significant adipose tissue overlying the pectoralis major muscle.
Journal of Cardiovascular Electrophysiology, Apr 30, 2004
A 16-year-old boy presented with exertional palpitations, which occurred particularly when he was... more A 16-year-old boy presented with exertional palpitations, which occurred particularly when he was playing tennis. There was no history of syncope or family history of sudden cardiac death. The boy was otherwise well and had not been taking any medications. ECG showed sinus rhythm with no evidence of preexcitation and a normal corrected QT interval. A 24-hour Holter monitor demonstrated an irregular broadcomplex tachycardia with varying QRS morphology. At electrophysiologic study, the HV interval was normal at 35 ms. During atrial pacing with a single extrastimulus, tachycardia with a variable cycle length was induced (Fig. 1). During tachycardia, the QRS complexes demonstrated varying degrees of left bundle branch block (LBBB) morphology. Following reinduction, tachycardia with a right bundle branch block (RBBB) morphology was present, with the variation in tachycardia cycle length less apparent (Fig. 2). What is the mechanism of the tachycardia, and what accounts for the variation in tachycardia cycle lengths?
Journal of Cardiovascular Electrophysiology, Aug 5, 2004
Focal atrial fibrillation (AF) may initiate with an irregular rapid burst of atrial ectopic (AE) ... more Focal atrial fibrillation (AF) may initiate with an irregular rapid burst of atrial ectopic (AE) activity from a pulmonary vein (PV) focus, but how AF is maintained it is not known. The crista terminalis (CT) is an important line of block in atrial flutter (AFL), but its role in AF has not been determined. The aim of this study was to examine the conduction properties of the CT during onset of AF. In 10 patients (mean age 38 +/- 8 years), we analyzed conduction across the CT during onset of focal AF from an arrhythmogenic PV and during pacing from the same PV at cycle lengths of 700 and 300 ms. A 20-pole catheter was positioned on the CT using intracardiac echocardiography. In 10 control patients with no history of AF, we analyzed conduction across the CT during pacing from the distal coronary sinus at 700 and 300 ms. In all 10 AF patients, AF was initiated with 1 to 9 AE beats (median 5) from a PV. During sinus rhythm, there were no split components (SC) recorded on the CT. During PV AE activity, discrete SC were recorded on the CT in all patients over 6.3 +/- 0.9 bipoles (3.7 +/- 0.3 cm). Maximal splitting of SC was 66 +/- 31 ms (37-139). There was an inverse relationship between AE coupling intervals and the degree of splitting between SC in all patients. Degeneration to AF was preceded by progressive decrement across the CT. SC were recorded during PV pacing at 700 and 300 ms (maximal distance between SC of 24 +/- 3 ms and 43 +/- 5 ms, respectively, P < 0.001). Maximum SC at CT in controls was 13 +/- 8 ms at 700 ms (P = 0.06 vs AF patients) and 16 +/- 9 ms at 300 ms (P < 0.01 vs AF patients). (1) These observations provide evidence of anisotropic, decremental conduction across the CT during onset of focal AF and during pacing from the same PV. A line of functional conduction block develops along this anatomic structure (CT). Whether this line of block acts as an initiator of AF or simply contributes passively to nonuniform fibrillatory conduction is unknown. (2) In some patients with focal AF, development of conduction block along the CT may provide a substrate for typical AFL.
Introduction In selecting patients that may benefit from cardiac resynchronisation therapy (CRT),... more Introduction In selecting patients that may benefit from cardiac resynchronisation therapy (CRT), dyssynchrony assessment by echocardiography based only upon the timing of regional contraction is limited by being inherently independent of underlying myocardial contractility. We hypothesised that patient selection may be enhanced using a strain-based parameter based not only the timing of myocardial segmental motion, but also on the amplitude of contraction, a potential measure of contractile reserve. We assessed a combined early and late strain index (ELSI) to predict CRT response. Methods Speckle tracking radial strain was performed in 67 heart failure patients scheduled for CRT (age 69±9 years, ischaemic 56%, QRS 154±12 ms, NYHA III/IV—63/4, ejection fraction 23±7%). The ELSI was calculated as the sum for each of the 12 non apical segments of the difference in peak radial strain and strain at aortic valve closure. CRT response was defined as a >15% reduction from baseline in LV end systolic volume (LVESV) at 6 months. The predictive value of the ELSI was compared to previously reported dyssynchrony measures including the SD of time to peak myocardial longitudinal velocity of the 12 non apical segments (Ts SD12), the anteroseptal–posterior wall radial strain delay (AS-P delay) and the SD of time to peak radial strain of 12 segments (Rs-SD12). Results Response to CRT occurred in 38/67 (57%) patients. Significant differences were seen between responders and non responders in the ELSI (91±45 vs 27±14%, p<0.01), AS-P delay (256±158 vs 94±87 ms) and the Rs-SD12 (143±62 vs 75±50 ms). There was no difference in the Ts SD12 between responders and non responders. The ELSI had the best correlation with LVESV reduction (r=0.61, p<0.001) and using an optimal cut-off of 40% (AUC=0.94), the ELSI was able to predict response to CRT with a sensitivity of 93% and specificity of 95%. This was much higher than for the AS-P (cut-off 130 ms, AUC=0.79, sensitivity 71%, specificity 74%) and Rs –SD12 (95 ms, AUC=0.82, sensitivity 73% specificity 75%). Conclusion A combined early and late strain parameter based on both the timing and amplitude of segmental strain has a stronger predictive value in determining CRT response compared to widely reported dyssynchrony parameters based on segmental timing alone.
Cardiac device implantations are increasingly carried out using local anaesthesia (LA) with intra... more Cardiac device implantations are increasingly carried out using local anaesthesia (LA) with intravenous conscious sedation. The advantages include reduction of patients' anxiety and discomfort, and avoidance of risks of general anaesthesia (GA). However, concerns about the safety of sedation used without an anaesthetist have been expressed. The National Patient Safety Agency (NPSA) has identified serious problems in the use of intravenous midazolam for conscious sedation and reliance on flumazenil for reversal of over-sedation [1]. The aim of the study is to determine the safety of intravenous conscious sedation in patients undergoing cardiac device implantation and to determine patients' experience and comfort using conscious sedation. All patients undergoing device implantations (pacemaker and Cardiac Resynchronisation Therapy (CRT) implantation, elective unit replacements (EUR) andpacing leads revision) under conscious sedation were eligible. Patients with devices that were implanted under GAwere excluded. Intravenous midazolam and fentanyl could be administered alone or in combination based on operators' discretion. LA with 1% lignocaine without adrenaline was used in all patients. All data were prospectively collected. A patient questionnaire (Appendix A) was given to patients late after the procedure to allow as much time for effects of sedation towear off. A pain score of 10 reflects the worst pain possible, whereas score 1 reflects no pain. Written informed consent for the procedures was obtained. Patient participation for the questionnaire was voluntary. Verbal informed consent was obtained as per the ethics committee of the hospital. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. The primary outcome was to determine the safety of conscious sedation administered without the presence of anaesthetist. The secondary outcome was to assess patients' satisfaction intraand postprocedure. Statistical comparisons for continuous data were performed using ANOVAs single factor, unpaired t-tests and chi-squared tests for categorical data. Logistic regression analysis was performed for multivariable predictors. All testswere two-sided and p values of a level≤0.05 were considered statistically significant.
Pacing and Clinical Electrophysiology, Mar 1, 2004
ABSTRACT The traditional pulse generator implantation site lies subcutaneous on the fascia of the... more ABSTRACT The traditional pulse generator implantation site lies subcutaneous on the fascia of the pectoralis major muscle. This article describes a subpectoral pocket approach, which on anatomic investigation is actually &quot;intrapectoral&quot; and offers a much improved cosmetic result with the potential advantage of less erosion. In the authors&#39; experience with over 1000 initial pacemaker implants and pulse generator replacements, the potential concerns of neurovascular and muscular damage have not been realized. There has been no pulse generator damage from the ribs, serious loculated hematomas, or unusual postoperative or chronic pain. From experience with pulse generator recalls, the replacement procedure has not been significantly more difficult than with the subcutaneous approach. The intrapectoral approach has now become the authors&#39; routine in patients without significant adipose tissue overlying the pectoralis major muscle.
Journal of Cardiovascular Electrophysiology, Apr 30, 2004
A 16-year-old boy presented with exertional palpitations, which occurred particularly when he was... more A 16-year-old boy presented with exertional palpitations, which occurred particularly when he was playing tennis. There was no history of syncope or family history of sudden cardiac death. The boy was otherwise well and had not been taking any medications. ECG showed sinus rhythm with no evidence of preexcitation and a normal corrected QT interval. A 24-hour Holter monitor demonstrated an irregular broadcomplex tachycardia with varying QRS morphology. At electrophysiologic study, the HV interval was normal at 35 ms. During atrial pacing with a single extrastimulus, tachycardia with a variable cycle length was induced (Fig. 1). During tachycardia, the QRS complexes demonstrated varying degrees of left bundle branch block (LBBB) morphology. Following reinduction, tachycardia with a right bundle branch block (RBBB) morphology was present, with the variation in tachycardia cycle length less apparent (Fig. 2). What is the mechanism of the tachycardia, and what accounts for the variation in tachycardia cycle lengths?
Journal of Cardiovascular Electrophysiology, Aug 5, 2004
Focal atrial fibrillation (AF) may initiate with an irregular rapid burst of atrial ectopic (AE) ... more Focal atrial fibrillation (AF) may initiate with an irregular rapid burst of atrial ectopic (AE) activity from a pulmonary vein (PV) focus, but how AF is maintained it is not known. The crista terminalis (CT) is an important line of block in atrial flutter (AFL), but its role in AF has not been determined. The aim of this study was to examine the conduction properties of the CT during onset of AF. In 10 patients (mean age 38 +/- 8 years), we analyzed conduction across the CT during onset of focal AF from an arrhythmogenic PV and during pacing from the same PV at cycle lengths of 700 and 300 ms. A 20-pole catheter was positioned on the CT using intracardiac echocardiography. In 10 control patients with no history of AF, we analyzed conduction across the CT during pacing from the distal coronary sinus at 700 and 300 ms. In all 10 AF patients, AF was initiated with 1 to 9 AE beats (median 5) from a PV. During sinus rhythm, there were no split components (SC) recorded on the CT. During PV AE activity, discrete SC were recorded on the CT in all patients over 6.3 +/- 0.9 bipoles (3.7 +/- 0.3 cm). Maximal splitting of SC was 66 +/- 31 ms (37-139). There was an inverse relationship between AE coupling intervals and the degree of splitting between SC in all patients. Degeneration to AF was preceded by progressive decrement across the CT. SC were recorded during PV pacing at 700 and 300 ms (maximal distance between SC of 24 +/- 3 ms and 43 +/- 5 ms, respectively, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Maximum SC at CT in controls was 13 +/- 8 ms at 700 ms (P = 0.06 vs AF patients) and 16 +/- 9 ms at 300 ms (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01 vs AF patients). (1) These observations provide evidence of anisotropic, decremental conduction across the CT during onset of focal AF and during pacing from the same PV. A line of functional conduction block develops along this anatomic structure (CT). Whether this line of block acts as an initiator of AF or simply contributes passively to nonuniform fibrillatory conduction is unknown. (2) In some patients with focal AF, development of conduction block along the CT may provide a substrate for typical AFL.
Introduction In selecting patients that may benefit from cardiac resynchronisation therapy (CRT),... more Introduction In selecting patients that may benefit from cardiac resynchronisation therapy (CRT), dyssynchrony assessment by echocardiography based only upon the timing of regional contraction is limited by being inherently independent of underlying myocardial contractility. We hypothesised that patient selection may be enhanced using a strain-based parameter based not only the timing of myocardial segmental motion, but also on the amplitude of contraction, a potential measure of contractile reserve. We assessed a combined early and late strain index (ELSI) to predict CRT response. Methods Speckle tracking radial strain was performed in 67 heart failure patients scheduled for CRT (age 69±9 years, ischaemic 56%, QRS 154±12 ms, NYHA III/IV—63/4, ejection fraction 23±7%). The ELSI was calculated as the sum for each of the 12 non apical segments of the difference in peak radial strain and strain at aortic valve closure. CRT response was defined as a >15% reduction from baseline in LV end systolic volume (LVESV) at 6 months. The predictive value of the ELSI was compared to previously reported dyssynchrony measures including the SD of time to peak myocardial longitudinal velocity of the 12 non apical segments (Ts SD12), the anteroseptal–posterior wall radial strain delay (AS-P delay) and the SD of time to peak radial strain of 12 segments (Rs-SD12). Results Response to CRT occurred in 38/67 (57%) patients. Significant differences were seen between responders and non responders in the ELSI (91±45 vs 27±14%, p<0.01), AS-P delay (256±158 vs 94±87 ms) and the Rs-SD12 (143±62 vs 75±50 ms). There was no difference in the Ts SD12 between responders and non responders. The ELSI had the best correlation with LVESV reduction (r=0.61, p<0.001) and using an optimal cut-off of 40% (AUC=0.94), the ELSI was able to predict response to CRT with a sensitivity of 93% and specificity of 95%. This was much higher than for the AS-P (cut-off 130 ms, AUC=0.79, sensitivity 71%, specificity 74%) and Rs –SD12 (95 ms, AUC=0.82, sensitivity 73% specificity 75%). Conclusion A combined early and late strain parameter based on both the timing and amplitude of segmental strain has a stronger predictive value in determining CRT response compared to widely reported dyssynchrony parameters based on segmental timing alone.
Cardiac device implantations are increasingly carried out using local anaesthesia (LA) with intra... more Cardiac device implantations are increasingly carried out using local anaesthesia (LA) with intravenous conscious sedation. The advantages include reduction of patients' anxiety and discomfort, and avoidance of risks of general anaesthesia (GA). However, concerns about the safety of sedation used without an anaesthetist have been expressed. The National Patient Safety Agency (NPSA) has identified serious problems in the use of intravenous midazolam for conscious sedation and reliance on flumazenil for reversal of over-sedation [1]. The aim of the study is to determine the safety of intravenous conscious sedation in patients undergoing cardiac device implantation and to determine patients' experience and comfort using conscious sedation. All patients undergoing device implantations (pacemaker and Cardiac Resynchronisation Therapy (CRT) implantation, elective unit replacements (EUR) andpacing leads revision) under conscious sedation were eligible. Patients with devices that were implanted under GAwere excluded. Intravenous midazolam and fentanyl could be administered alone or in combination based on operators' discretion. LA with 1% lignocaine without adrenaline was used in all patients. All data were prospectively collected. A patient questionnaire (Appendix A) was given to patients late after the procedure to allow as much time for effects of sedation towear off. A pain score of 10 reflects the worst pain possible, whereas score 1 reflects no pain. Written informed consent for the procedures was obtained. Patient participation for the questionnaire was voluntary. Verbal informed consent was obtained as per the ethics committee of the hospital. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. The primary outcome was to determine the safety of conscious sedation administered without the presence of anaesthetist. The secondary outcome was to assess patients' satisfaction intraand postprocedure. Statistical comparisons for continuous data were performed using ANOVAs single factor, unpaired t-tests and chi-squared tests for categorical data. Logistic regression analysis was performed for multivariable predictors. All testswere two-sided and p values of a level≤0.05 were considered statistically significant.
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