Changes in Right Ventricular Function with Exercise in Healthy Subjects: Optimal Parameters and Effects of Gender and Age.

BACKGROUND: Right ventricular (RV) function augments with exercise, and loss of this adaptive ability often determines symptoms. Reports on exercise-related changes in RV function in healthy subjects are sparse. In this study, healthy volunteers were prospectively recruited, and changes in RV function with exercise were examined, optimal parameters determined, and the effects of gender and age examined. METHODS: Treadmill exercise stress echocardiography with concurrent expired gas analysis was performed in 121 healthy volunteers. Parameters of RV systolic function (RV fractional area change, Doppler tissue s' velocity, and systolic strain and strain rate) and diastolic function (peak E and A velocity, Doppler tissue e', a' and early and late diastolic strain rate) were evaluated at baseline and after exercise, with the difference (Δ) being systolic and diastolic reserve. Changes in pulmonary arterial pressure (PAP) was measured when accurate estimation was possible. RESULTS: Most systolic functional parameters were augmented with exercise. However, systolic augmentation decreased with age (Δs': r = -0.31, P < .01; Δ strain: r = -0.28, P = .008; Δ systolic strain rate: r = -0.31, P < .01). Similar changes were observed with diastolic function (Δe': r = -0.33, P < .01; Δ early diastolic strain rate r = -0.20, P = .04). In the subgroup with PAP measurements, ΔPAP (r = 0.32, P < .01) increased with age. Men had greater augmentation of systolic reserve, but differences were negated when corrected for workload. S' velocity was the most robust measure of RV systolic function. CONCLUSIONS: There is a modest yet significant reduction in RV systolic and diastolic reserve with age, with an increase in PAP. S' velocity is a robust and feasible measure that should be considered given the increasing use of stress testing to evaluate RV function.

Effects of age and gender on right ventricular systolic and diastolic function using two-dimensional speckle-tracking strain.

BACKGROUND: Accurate assessment of the right ventricle is increasingly important. Measures of right ventricular (RV) systolic function, including fractional area change, tissue Doppler (s' velocity), and tricuspid annular plane systolic excursion, show significant variation, and the impacts of age and gender are unclear. The aim of this study was to determine the effects of gender and age on global and segmental RV systolic and diastolic function using both traditional echocardiographic and two-dimensional strain parameters. METHODS: Detailed transthoracic echocardiographic studies were performed on 142 healthy adult volunteers, with particular emphasis on the right ventricle to determine RV dimensions and function, including fractional area change, tricuspid annular plane systolic excursion, s' velocity, global and segmental systolic strain, and systolic, early diastolic, and late diastolic strain rates. RESULTS: Tricuspid annular plane systolic excursion (r = -0.4, P < .001) and RV s' velocity (r = -0.5, P < .001) as well as diastolic functional parameters, including transtricuspid peak E velocity and RV free wall e' velocity (r = -0.4, P < .001), decreased with age. Global systolic strain was also reduced, with differential reductions in basal and mid segmental strain with age. Early diastolic strain rate decreased, with a corresponding increase in late diastolic strain rate. RV function parameters, including fractional area change, e' velocity, strain, and strain rate, were significantly lower in men. CONCLUSIONS: RV functional analysis by two-dimensional strain demonstrates a small yet significant change in global and segmental RV function with age and gender, and therefore adjustment for these measures is required in the evaluation of RV function.

Circumflex coronary artery to left atrium fistula caused by mitral isthmus ablation.

Mitral isthmus ablation is an important component of catheter ablation for persistent atrial fibrillation and mitral isthmus dependent flutters. We describe a case where mitral isthmus ablation caused a fistula between the left circumflex artery and the left atrium and symptomatic ischaemia. The fistula was successfully closed with a covered stent.

Primary radiofrequency ablation of ventricular tachycardia early after myocardial infarction: evaluation in an ovine model.

BACKGROUND: Ventricular tachycardia (VT) is a significant complication of myocardial infarction. Radiofrequency ablation for postinfarct VT is reserved for drug refractory VT or VT storms. Our hypothesis is that radiofrequency ablation in the early postinfarct period could abolish or diminish late recurrences of VT. METHODS AND RESULTS: Myocardial infarct was induced by balloon occlusion of the left anterior descending artery in 35 sheep. The 25 survivors underwent programmed ventricular stimulation and electroanatomical mapping 8 days postinfarct. Animals with inducible VT (12 out of 25 animals) underwent immediate radiofrequency ablation. Further VT inductions were performed 100 and 200 days postinfarct. At day 8, 3.0±0.9 VT morphologies per animal were inducible. All were successfully ablated with 24±6 applications of radiofrequency energy. All had ablations on the left ventricular endocardium, and 67% had ablations on the right ventricular aspect of the interventricular septum. All targeted arrhythmias were successfully ablated acutely. One animal was euthanized because of hypotension from a serious pericardial effusion. The other 11 survived and remained arrhythmia free on subsequent inductions on the 100th and 200th days (P<0.001). The 13 animals without inducible VT remained noninducible at the subsequent studies. A historical control arm of 9 animals with inducible VT at day 8 remained inducible at day 100. CONCLUSIONS: Radiofrequency ablation on the eighth day after infarction abolished inducibility of VT at late induction studies ≤200 days in an ovine model. Early identification and ablation of VT after infarction may prevent or reduce late ventricular arrhythmias but needs to be validated in clinical studies.

Evolution of ventricular tachycardia and its electrophysiological substrate early after myocardial infarction: an ovine model.

BACKGROUND: Sudden arrhythmic death after myocardial infarction (MI) is most frequent in the first month. Early programmed ventricular stimulation (within 1 week) post-MI has been able to identify long-term ventricular tachycardia (VT) occurrence. We aimed to determine the timing of development and stabilization of VT circuits after MI and how the evolution of the underlying substrate differs with VT inducibility. METHODS AND RESULTS: MIs were induced in 36 sheep. The 21 survivors underwent serial electroanatomic mapping and programmed ventricular stimulation. Animals were classified as VTpos (inducible VT) or VTneg (noninducible VT) at day 8. Forty-three percent of MI survivors were VTpos on day 8 (9/21), and all remained inducible on day 100 with 1.5 (1.0-2.0) and 1.0 (1.0-2.0) morphologies per animal on days 8 and 100, respectively. Twelve-lead electrocardiogram matched in 15 of 19 VTs between days 8 and 100. The earliest presystolic ventricular activations during VT circuits were in similar locations at the 2 time points. The 12 VTneg animals remained noninducible on day 100. There was no difference in voltage or velocity substrate with time or inducibility. The area with fractionated signals increased with time and VT inducibility. VTpos animals had more linear regions of slowed conduction forming conducting channels. CONCLUSIONS: The inducibility and earliest presystolic endocardial activation sites of VT as well as voltage and velocity substrate on day 8 predicted those on day 100 postinfarct, indicating early formation and stabilization of the arrhythmogenic substrate. VT inducibility was influenced by the distribution of conducting channels and increased complex fractionated signals.

Direct transthoracic access to the left ventricle for catheter ablation of ventricular tachycardia.

BACKGROUND: Percutaneous approaches for radiofrequency ablation of ventricular tachycardia (VT) in the left ventricle are typically transarterial retro-aortic, antegrade transmitral via an interatrial septal puncture, or epicardial. However, all 3 approaches may be contraindicated in certain cases. We describe 2 cases of VT ablation in which aortic and mitral valve replacements did not permit utilization of any of these techniques. METHODS AND RESULTS: Direct access to the left ventricular cavity was achieved with a percutaneous puncture through the intercostal space overlying the apex in the first case and through a left minithoracotomy in the second. A sheath was then inserted via the Seldinger technique, allowing catheter access for mapping and ablation of the VT. After successful ablation, the sheaths were withdrawn and hemostasis was achieved. A large left hemothorax occurred from the left ventricular apical puncture in the first case. Direct closure with a purse-string suture in the second case achieved hemostasis. CONCLUSIONS: Direct percutaneous left ventricular puncture is a viable option for mapping and ablation of left ventricular VT. A minithoracotomy allows better hemostatic control. This technique has a role when other percutaneous approaches are contraindicated.

Predictive value of ST resolution analysis performed immediately versus at ninety minutes after primary percutaneous coronary intervention.

ST segment resolution (STR) predicts epicardial and microvascular reperfusion after primary percutaneous coronary intervention (PPCI) or thrombolysis for ST-elevation myocardial infarction. Immediate restoration of epicardial coronary flow, with improved microvascular perfusion, is much more likely with PPCI. However, the predictive value of immediate STR compared to 90 minutes after PPCI remains unknown. In 622 consecutive patients with ST-elevation myocardial infarction (mean age 59 +/- 13 years), 217 had complete STR immediately after PPCI (group A), 188 had complete STR only at 90 minutes (group B), and 217 had incomplete STR at either point (group C). The primary end point was mortality and adverse cardiovascular events ([MACE] death, nonfatal repeat myocardial infarction, and heart failure). Group A had a greater left ventricular ejection fraction (53%, 47%, and 46%, p <0.001) and lower all-cause mortality (1.8%, 3.2%, and 6%, p = 0.07), lower heart failure (1.8%, 4.3%, and 7.8%, p <0.001), and MACE (5.1%, 9.6%, and 16.1%, p = 0.001) at 30 days compared to groups B and C, respectively. The rate of MACE at 1 year was 7.6%, 17.1%, and 20.2% in groups A, B, and C, respectively (p <0.001). Immediate STR independently predicted MACE (adjusted hazard ratio 0.36, 95% confidence interval 0.21 to 0.61, p = 0.001, group A vs C), and STR at 90 minutes did not. In conclusion, STR analysis performed immediately after PPCI provided superior differentiation for adverse cardiovascular events compared to STR at 90 minutes. Immediate STR should be the contemporary goal of reperfusion with PPCI.

Prognostic impact of Q waves on presentation and ST resolution in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention.

Q waves can develop early in infarction and indicate infarct progression better than symptom duration. ST resolution (STR) is a predictor of reperfusion success. Our aim was to assess the prognostic impact of Q waves on presentation and STR after primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction. The combined end point was of mortality and adverse cardiovascular events (MACE; death, repeat myocardial infarction, or heart failure). Q waves on presentation (Q wave, n = 332; no Q wave, n = 337) was associated with significantly less mean STR, greater incidence of akinetic, dyskinetic, or aneurysmal regional wall motion, lower left ventricular ejection fraction, and worse in-hospital and 1-year MACEs (1 year 24% vs 8.2%, p <0.001). In addition, Q waves on presentation compared to no Q waves were associated with worse 1-year MACE regardless of infarct presentation in < or =3 hours, infarct location, and adequate STR (> or =70%). Q waves on presentation and inadequate STR (<70%), but not symptom duration, were independent predictors of MACE by multivariable analysis (adjusted hazard ratios of 2.7 and 2.4 for Q waves and STR, respectively). Compared to group A (no Q waves on presentation with STR), patients in group B (no Q waves with inadequate STR), group C (Q waves with STR), and group D (Q waves with inadequate STR) had hazard ratios of 3.0, 3.6, and 7.7, respectively (p <0.05) for the occurrence of MACE. In conclusion, assessment of Q-wave status on presentation and STR immediately after PPCI provides a simple and early clinical predictor of outcomes in ST-elevation myocardial infarction.