Pacing right ventricular

Isolated right ventricular tissues were used to measure the contribution of P-AR signaling to contractility. Cardiac inotropy was monitored in isolated, paced right ventricular muscle strips. Preparations from pr AR-KO mice failed to show any responsiveness to isoproterenol administration, while wild-type preparations showed robust inotropic responses (28). This lack of contractile response is not caused by generalized hyporesponsiveness of the contractile apparatus because prAR-KO ventricles responded normally to activators of adenylyl cyclase such as forskolin. Surprisingly, disruption of both pr and P2-ARs has only modest effects on resting left ventricular contractility in vivo. When contractility was assessed with a micromanometer-tipped catheter, -i-dP/dt was reduced by 20% and -dP/dt was reduced by 12% in p /prAR-KO mice compared to wild-type mice (30). 

A (a) Biventricular followed by left ventricular pacing, (b) Left and right ventricular pacing, right ventricular sensing. 

Abstract Two thirds of the nearly half a million deaths per year in the United States due to sudden cardiac death (SCD) is attributed to coronary artery disease (CAD) and most commonly results from untreated ventricular tachyarrhythmias. Patients with ischemic cardiomyopathy and left ventricular dysfunction are at highest risk for SCD, but this still defines only a small subset of patients who will suffer SCD. Multiple lines of evidence now support the superiority of implantable cardioverter defibrillator (ICD) therapy over antiarrhythmic therapy for both primary and secondary prevention of SCD in advanced ischemic heart disease. Optimization of ICD therapy in advanced ischemic cardiomyopathy includes preventing right ventricular pacing as well as the use of highly effective anti-tachycardia pacing to reduce the number of shocks. While expensive, ICD therapy has been shown to compare favorably to the accepted standard of hemodialysis in cost effectiveness analyses. 

Gold MR, Shorofsky SR, Metcalf MD, Feliciano Z, Fisher ML, Gottlieb SS. The acute hemodynamic effects of right ventricular septal pacing in patients with congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy. Am. J. Cardiol. 1997 79 679-81. 

Zile MR, Blaustein AS, Shimizu G, Gaasch WH. Right ventricular pacing reduces the rate of left ventricular relaxation and filling. J. Am. Coll. Cardiol. 1987 10 702-9. 

Alboni P, Scarfo S, Fuca G, Mele D, Dinelli M, Papar-ella N. Short-term hemodynamic effects of DDD pacing from ventricular apex, right ventricular outflow tract and proximal septum. G. Ital. Cardiol. 1998 28 237-41. 

Barin ES, Jones SM, Ward DE, Camm AJ, Nathan AW. The right ventricular outflow tract as an alternative permanent pacing site long-term follow-up. Pacing Clin. Electrophysiol. 1991 14 3-6. 

Giudici MC, Thornburg GA, Buck DL, et al. Comparison of right ventricular outflow tract and apical lead permanent pacing on cardiac output. Am. J. Cardiol. 1997 79 209-12. 

In healthy volunteers, tocainide produced a slight depression in His-Purkinje conduction as well as a slightly delayed enhancement of A-V node conduction during atrial pacing. No significant alterations in heart rate, right ventricular ERP or the excitation thresholds of atrial or ventricular muscle were observed in these subjects. 

Castellanos A, Zoble R, Procacci PM, Myerburg RJ, Serkovits SV. St-qR pattern new sign for diagnosis of anterior myocardial infarction during right ventricular pacing. Br Heart J 1973 35 1161. 

Nahlawi M, Waligora M, Spies SM, Bonow RO, Kadish AH, Goldberger J. Left ventricular function during and after right ventricular pacing. J Am Coll Cardiol 2004 44 1883-8. 

Duray GZ, Israel CW, Pajitnev D, Hohnloser SH. Upgrading to biventricular pacing/defibrillation systems in right ventricular paced congestive heart failure patients prospective assessment of procedural parameters and response rate. Europace 2008 10 48-52. 

The most common sensor is the activity sensor, which uses any of a variety of technologies (e.g., piezoelectric crystals and accelerometers) to detect body movement. Systems using a transthoracic-impedance sensor to estimate pulmonary minute ventilation or cardiac contractility are also commercially available. Numerous other sensors (e.g., stroke volume, blood temperature or pH, oxygen saturation, and right ventricular pressure) have been researched or market-released at various times. Some systems are dual-sensor, combining the best features of each sensor in a single pacing system. 

Tse HF, Lau CP (1997) Long-term effects of right ventricular pacing on myocardial perfusion and function. J Am Coll Cardiol 29 744-749... 

Pastore G, Noventa F, Piovesana PG et al (2008) Left ventricular dyssynchrony resulting from right ventricular apical pacing. Relevance of baseline assessment. Pacing Clin Electrophysiol 31 1456-1462... 

TLR, transvenous lead removal A, atrial RV, right ventricular LV, left ventricular PL, pacing leads ICD, implantable cardioverter defibrillator L, leads... 

Fig. 7.2 Serial anteroposterior fluoroscopic images taken during transvenous removal of a left-sided dual-chamber implantable cardioverter-defibrillator (ICD) system. After placement of a temporary right-ventricular (RV) pacing system

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