Functional consequences of the right ventricular isolation procedure

Arrhythmogenic forms of heart failure in children

There are various underlying causes of tachycardia-induced cardiomyopathy (TIC), and it is critical that it be considered in any patient who presents with a newly diagnosed dilated cardiomyopathy. Unlike most other forms of cardiomyopathy, TIC should be considered a treatable form of cardiomyopathy and it is imperative that the diagnosis be fully considered. A 12-lead ECG should be obtained in all patients with a dilated cardiomyopathy. Prompt diagnosis and therapy of this relatively uncommon cause of heart failure is critical and has the potential to completely reverse the ventricular dysfunction that may be present in this abnormality.

Pacing to Restore Right Ventricular Contraction After Surgical Disconnection for Arrhythmia Control in Right Ventricular Cardiomyopathy

Ventricular tachycardia in ARVC (arrhythmogenic right ventricular cardiomyopathy) is typically managed by ICD implantation, with a limited role of catheter ablation. Surgical disconnection of the right ventricular (RV) has been used to control ventricular tachycardia (VT) in ARVC, but it often led to refractory RV failure due to loss of RV contraction after surgery. We report multisite pacing to recruit the disconnected RV to prevent ventricular failure.

Pulmonary blood flow profiles with reduced right ventricular function in lambs

The determinants of right ventricular (RV) performance with damaged RV free wall, such as occurs with RV infarction, are still unclear. Using 20-MHz Doppler ultrasound equipment, we investigated the changes in pulmonary blood flow velocity profiles before and after ligation of the right coronary artery. RV dp/dt, stroke volume, RV stroke work, aortic pressure and cardiac output decreased and central venous pressure rose after the ligation. The RV stroke work-end-diastolic pressure relationship indicated impaired RV function following ligation. We observed shortened acceleration time (65.0 +/- 15.1 vs 54.4 +/- 6.2 ms, P < 0.05) and reduced maximum velocity of forward flow (59.0 +/- 5.9 vs 52.5 +/- 7.6 cm/s, P < 0.05) after the ligation. Acceleration was interrupted earlier after ligation than before ligation. These alterations in flow are thought to be a consequence of the altered movement of the RV free wall and ventricular septum induced by RV infarction.

Right ventricular dynamics during left ventricular assistance in closed-chest dogs

To determine the effects of left ventricular assist device (LVAD) support on global right ventricular (RV) systolic mechanics, 8 closed-chest, conscious, sedated dogs were studied after placement of an LVAD (left ventricle to femoral artery bypass) and implantation of 27 tantalum markers into the left ventricular and RV walls for computation of biventricular volumes and geometry. Biplane cinefluoroscopic marker images and hemodynamic parameters were recorded during transient vena caval occlusion at various levels of LVAD support. Right ventricular contractility was assessed using end-systolic elastance and preload recruitable stroke work, and the myocardial (pump) efficiency of converting mechanical energy to external work (stroke work/total pressure-volume area) was calculated. With full LVAD support, RV end-diastolic volume increased from 60 +/- 15 to 62 +/- 17 mL (p < 0.002), pulmonary artery input impedance decreased from 940 +/- 636 to 587 +/- 347 dyne.s/cm5 (p < 0.007), and measurement of RV and left ventricular septal-free wall dimensions demonstrated a significant leftward septal shift (p < 0.0005). Global RV end-systolic elastance and preload recruitable stroke work decreased from 2.4 +/- 1.0 to 1.7 +/- 0.7 mm Hg/mL (p < 0.004) and 14.1 +/- 3.3 to 12.1 +/- 3.9 mm Hg (p < 0.02), respectively; however, RV power output and myocardial efficiency did not change significantly (p > 0.74 and p > 0.33, respectively). Therefore, during LVAD support, global RV contractility is impaired with leftward septal shifting, but RV myocardial efficiency and power output are maintained through a decrease in RV afterload and an increase in RV preload.