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ABSTRACT: The optimal site to permanently pace the right ventricle (RV) has yet to be determined. To address this issue, three randomized prospective multicenter clinical trials are in progress comparing the long-term effects of RV apical versus septal pacing on left ventricular (LV) function. The three trials are Optimize RV Selective Site Pacing Clinical Trial (Optimize RV), Right Ventricular Apical and High Septal Pacing to Preserve Left Ventricular Function (Protect Pace), and Right Ventricular Apical versus Septal Pacing (RASP).
Patients that require frequent or continuous ventricular pacing are randomized to RV apical or septal pacing. Optimize RV excludes patients with LV ejection fraction <40% prior to implantation, whereas the other trials include patients regardless of baseline LV systolic function. The RV septal lead is positioned in the mid-septum in Optimize RV, the high septum in Protect Pace, and the mid-septal inflow tract in RASP. Lead position is confirmed by fluoroscopy in two planes and adjudicated by a blinded panel. The combined trials will follow approximately 800 patients for up to 3 years.
The primary outcome in each trial is LV ejection fraction evaluated by radionuclide ventriculography or echocardiography. Secondary outcomes include echo-based measurements of ventricular/atrial remodeling, 6-minute hall walk distance, brain natriuretic peptide levels, and clinical events (atrial tachyarrhythmias, heart failure, stroke, or death).
These selective site ventricular pacing trials should provide evidence of the importance of RV pacing site in the long-term preservation of LV function in patients that require ventricular pacing and help to clarify the optimal RV pacing site.
Pacing and Clinical Electrophysiology 05/2009; 32(4):426-33. · 1.35 Impact Factor
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Europace 08/2008; 10(9):1118-20. · 1.98 Impact Factor
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Heart (British Cardiac Society) 09/2007; 93(8):944. · 4.22 Impact Factor
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ABSTRACT: To measure changes in transventricular impedance during arrhythmias.
Patients were studied during electrophysiological studies. A quadrapolar catheter was positioned at the right ventricular apex (RVA) and a decapolar catheter within the coronary sinus (CS). Transventricular impedance was measured by injecting a subthreshold biphasic rectangular pulse of 600 micro A between poles 1 of the CS catheter and pole 1 of the RVA catheter and the voltage measured between CS pole 10 and RVA catheter pole 4. Stroke impedance (SZ), surface ECG, intracardiac electrogram (IEGM), and invasive femoral artery blood pressure (FAP) were recorded. Twenty-eight patients were analysed, 5 with inducible, haemodynamically unstable ventricular tachycardia (VT) (HUSVT), 5 with stable VT (HSVT). During HUSVT, the SZ value reduced to 22% (range 0.15-0.32 P < 0.001) in comparison with sinus rhythm. For HSVT, the SZ value reduced to 58% (range 0.33-0.88) P < 0.01, significantly different from HUSVT (P < 0.01). There was a good correlation between reduction of SZ and arterial pulse pressure (PP) during arrhythmias (r = 0.95).
Changes in SZ strongly correlated with PP amplitude. Transventricular impedance fell significantly during unstable arrhythmias and may be useful as a sensor capable of haemodynamic discrimination.
Europace 02/2007; 9(2):122-6. · 1.98 Impact Factor
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ABSTRACT: To determine the feasibility of discriminating haemodynamically stable from unstable arrhythmias using right ventricular (RV) unipolar intracardiac impedance (Z).
A quadrapolar temporary pacing electrode was positioned at the RV apex and unipolar impedance was measured between the tip electrode and a surface patch electrode. Changes in peak-to-peak Z amplitude were measured simultaneously with surface ECG and blood pressure during induced arrhythmias. Haemodynamic instability was defined as a systolic pressure of <90 mmHg. There were 25 episodes of ventricular fibrillation (VF) induced in 15 patients, 18 episodes of ventricular tachycardia in 16 patients, and 33 episodes of supraventricular tachycardia (SVT) in 16 patients. Compared with the baseline rhythm, mean Z amplitude reduced from 51.3+/-7.7 to 11.2+/-7.4 Ohm (P<0.001) during VF, from 52.2+/-6.3 to 21.7+/-10.1 Ohm (P<0.01) during haemodynamically unstable VT, from 55.0+/-6.9 to 39.9+/-11 Ohm (ns) during stable VT, and from 56.4+/-8.4 to 36.9+/-9.3 Ohm during SVT (P<0.001).
Right ventricular unipolar impedance is an adequate sensor for determining mechanical ventricular contraction and acts as a surrogate marker for a fall in arterial blood pressure during VF. However, for ventricular and supraventricular tachycardias, variations between patients did not allow adequate discrimination between stable and unstable arrhythmias.
Europace 11/2006; 8(11):988-93. · 1.98 Impact Factor
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ABSTRACT: The American Heart Association meeting reported the results of several clinical trials of particular interest to those who care for patients with heart failure. Omega-3 fatty acids were associated with a trend to increased recurrence of ventricular arrhythmias but not mortality in patients with an implantable debrillator. The ACTIV in CHF study provides more evidence of a therapeutic role for arginine vasopressin antagonists in the treatment of heart failure. The VALIANT study provides further evidence to suggest that a combination of angiotensin receptor antagonist and ACE inhibitor does not reduce mortality but may reduce morbidity in post-MI patients with heart failure or major LV systolic dysfunction. A study of autologous bone marrow cell transplantation into myocardial scar give gave encouraging results. SPORTIF V showed ximelagation to be as effective as warfarin but with improved safety. ORBIT and PAD showed public access defibrillators saved lives but questioned their cost effectiveness. DEFINITE supported a role for ICDs in patients with non-ischemic cardiomyopathy, although cost-effectiveness remains in doubt.
European Journal of Heart Failure 02/2004; 6(1):109-15. · 4.90 Impact Factor
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ABSTRACT: Cardiac resynchronization therapy (CRT) is potentially an important new treatment for patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony. There is growing evidence that CRT can improve symptoms although it is possible that similar benefits could be obtained by skillful manipulation of pharmacological therapy. There is also preliminary but inconclusive evidence to suggest that CRT alone or in synergy with an implantable cardiac defibrillator (ICD) may reduce morbidity and mortality. However, fashion is in danger of overtaking facts and it is important to ensure that benefits are not only statistically proven but clinically meaningful and cost-effective. Optimal timing of intervention and patient selection will be essential to ensure that treatment is deployed efficiently. If CRT with or without ICD becomes part of mainstream therapy for heart failure this will have far-reaching consequences for heart failure management. Implantation is a skilled and often time-consuming procedure. Long-term management of both CRT and ICD is likely to provide challenges in terms of lead technology, pacing thresholds and device management. Heart failure physicians will have to learn new skills and collaborate more closely with electrophysiologists. Such developments, in addition to the need for complex pharmacological interventions will accelerate the move away from general practice and towards specialist care for this most common of malignant diseases. If CRT does reduce mortality, it will graduate from an adjunctive therapy which could be used to an essential one that should be used as part of routine therapy for appropriate patients. Currently, CRT is a symptomatic therapy for patients with severe heart failure resistant to intensive pharmacological therapy delivered by a heart failure specialist.
Cardiac Electrophysiology Review 01/2004; 7(4):421-9.
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ABSTRACT: Cardiac resynchronization therapy (CRT) is potentially an important new treatment for patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony. There is growing evidence that CRT can improve symptoms although it is possible that similar benefits could be obtained by skilful manipulation of pharmacological therapy. There is also preliminary but inconclusive evidence to suggest that CRT alone or in synergy with an implantable cardiac defibrillator (ICD) may reduce morbidity and mortality. However, fashion is in danger of overtaking facts and it is important to ensure that benefits are not only statistically proven but clinically meaningful and cost-effective. Optimal timing of intervention and patient selection will be essential to ensure that treatment is deployed efficiently.If CRT with or without ICD becomes part of mainstream therapy for heart failure this will have far-reaching consequences for heart failure management. Implantation is a skilled and often time-consuming procedure. Long-term management of both CRT and ICD is likely to provide challenges in terms of lead technology, pacing thresholds and device management. Heart failure physicians will have to learn new skills and collaborate more closely with electrophysiologists. Such developments, in addition to the need for complex pharmacological interventions will accelerate the move away from general practice and towards specialist care for this most common of malignant diseases.If CRT does reduce mortality, it will graduate from an adjunctive therapy which could be used to an essential one that should be used as part of routine therapy for appropriate patients. Currently, CRT is a symptomatic therapy for patients with severe heart failure resistant to intensive pharmacological therapy delivered by a heart failure specialist.
Cardiac Electrophysiology Review 11/2003; 7(4):421-429.
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European Heart Journal 04/2003; 24(5):384-90. · 10.48 Impact Factor
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ABSTRACT: Heart failure is a common debilitating condition for which pharmacologic therapy thus far has provided only partial relief. Despite, and sometimes because of, medical therapy, the overall prognosis remains poor, with high rates of sudden death and death from progressive heart failure. Device-based therapies offer considerable promise for relief of symptoms and for improving prognosis. It is clear that implantable defibrillators should be considered for patients with heart failure who have been resuscitated from ventricular fibrillation or sustained ventricular tachycardia. Several large studies currently are investigating the effects of implantable defibrillators on total mortality in patients with major left ventricular systolic dysfunction but without other risk factors for sudden death. Cardiac resynchronization is a promising new therapy that may relieve the symptoms of heart failure in appropriately selected patients resistant to optimal pharmacologic therapy. Two large trials (CARE-HF and COMPANION) currently are investigating the effects of cardiac resynchronization therapy (CRT) on morbidity and mortality. It is important that those involved in these trials enroll patients quickly and minimize device implantation into patients who have not been assigned this therapy (cross-overs). Overenthusiasm for the benefits that doctors believe devices might bring could destroy the future basis for our clinical practice, denying future generations of patients and the doctors themselves access to what they believe to be effective treatments.
Journal of Cardiovascular Electrophysiology 02/2002; 13(1 Suppl):S73-91. · 3.06 Impact Factor
