Acute Hemodynamic Response Research Articles

Haemodynamic vector personalization of a quadripolar left ventricular lead used for cardiac resynchronization therapy: use of surface electrocardiogram and interventricular time delays.

The choice of left ventricular pacing configurations (LVPCs) of quadripolar leads used for cardiac resynchronization therapy (CRT) affects haemodynamic response and thus may be a tool for device optimization. The value of surface electrocardiograms and interventricular time delays (IVDs) for optimization is unknown. Sixteen patients implanted with a CRT device with a quadripolar LV lead underwent invasive testing of LV dP/dt. QRS durations at baseline (bl) and during biventricular pacing (biv) were measured using different LVPCs (total of 141 LVPCs; 8.8 per patient). Variations in QRS duration during biv were calculated for each patient (ΔQRS) and, when compared with intrinsic QRS duration, for all LVPCs (ΔQRSLVPC). Interventricular time delays between the poles of the LV lead were obtained from intracardiac electrograms. ΔIVD was calculated as IVDmax - IVDmin. Parameters were correlated with LV dP/dt. ΔQRS and ΔQRSLVPC both significantly correlated with LV dP/dt (P < 0.01). Correlation was found for patients with ischaemic (P < 0.001) and non-ischaemic cardiomyopathy (P < 0.05), and for patients with bl QRS duration >168 ms (P < 0.001), but not <168 ms (P = ns). The LVPC with shortest QRS duration also yielded maximal LV dP/dt in 6 of 16 patients (37.5%), and was equal or better in LV dP/dt in 12 of 16 patients (75%). ΔIVD neither correlated with ΔQRS nor ΔLV dP/dt. ΔQRS predicts the maximal value of vector personalization in the individual. Reductions in QRS width, but not IVDs, correlate with acute haemodynamic response. Intraindividually, in 75% of patients, the LVPC with the shortest QRS duration gives equal or superior haemodynamic results when compared with the LVPC with longest QRS duration.

Does cardiac resynchronization therapy benefit patients with right bundle branch block: cardiac resynchronization therapy has a role in patients with right bundle branch block.

Does cardiac resynchronization therapy benefit patients with right bundle branch block: cardiac resynchronization therapy has a role in patients with right bundle branch block.

SP0055 Physical Therapy in Rheumatology - Interesting Studies

Any treatment of rheumatic diseases without physical therapy (PT) is always incomplete, and PT can not be replaced by anything else. Furthermore, joint and spine mobility and function can only...

Delayed Trans-Septal Activation Results in Comparable Hemodynamic Effect of Left Ventricular and Biventricular Endocardial Pacing

Background— We sought to compare left ventricular (LV epi ) and biventricular epicardial pacing (BIV epi ) with LV (LV endo ) and BIV endocardial pacing (BIV endo ) in patients with chronic heart failure with an emphasis on the underlying electrophysiological mechanisms and hemodynamic effects. Methods and Results— Ten patients with chronically implanted cardiac resynchronization devices underwent temporary LV endo and BIV endo pacing with an LV endocardial roving catheter. A pressure wire and noncontact mapping array were placed to the LV cavity to measure LVdP/dt max and perform electroanatomical mapping. At the optimal endocardial position, the acute hemodynamic response (AHR) was superior to epicardial stimulation, the AHR to BIV endo pacing and LV endo pacing being comparable (21±15% versus 22±17%; P =NS). During intrinsic conduction, QRS duration was 185±30 ms, endocardial LV total activation time 92±27 ms, and trans-septal activation time 60±21 ms. With LV endo pacing, QRS duration (187±29 ms; P =NS) and endocardial LV total activation time (91±23 ms; P =NS) were comparable with intrinsic conduction. There was no significant difference in endocardial LV total activation time between LV endo and BIV endo pacing (91±23 versus 85±15 ms; P =NS). Assessment of isochronal maps identified slow trans-septal conduction with both LV endo and BIV endo pacing resulting in activation of almost the entire LV endocardium prior to septal breakout, thereby limiting any possible fusion with either pacing mode. Conclusions— The equivalent AHR to LV endo and BIV endo pacing may be explained by prolonged trans-septal conduction limiting fusion of electrical wavefronts. The optimal AHR was associated with predominantly LV pre-excitation and depolarization. Our results suggest that LV pacing alone may offer a viable endocardial stimulation strategy to achieve cardiac resynchronization.

Acute Hemodynamic Response and Uremic Toxin Removal in Conventional and Extended Hemodialysis and Hemodiafiltration: A Randomized Crossover Study

Intensive hemodialysis (HD) may have significant benefits. Recently, the role of extended hemodiafiltration (HDF) has gained interest. The aim of this study was to evaluate the acute effects of extended HD and HDF on hemodynamic response and solute removal. Randomized crossover trial. Stable patients with end-stage renal disease undergoing conventional HD. 13 patients randomly completed a single study of 4-hour HD (HD4), 4-hour HDF (HDF4), 8-hour HD (HD8), and 8-hour HDF (HDF8), with a 2-week interval between study sessions. Between study sessions, patients received routine conventional HD treatments. Acute hemodynamic effects and uremic toxin clearance. Blood pressure and heart rate, pulse wave analysis, cardiac output, and microvascular density by sublingual capillaroscopy, as well as relative blood volume and thermal variables, were measured. Clearance and removal of uremic toxins also were studied. Long treatments showed more stability of peripheral systolic blood pressure (change during HD4, -21.7±15.6 mm Hg; during HDF4, -23.3±20.8 mm Hg; during HD8, -6.7±15.2 mm Hg [P=0.04 vs. HD4; P=0.08 vs. HDF4]; and during HDF8, -0.5±14.4 mm Hg [P=0.004 vs. HD4; P=0.008 vs. HDF4]). A similar observation was found for peripheral diastolic and central blood pressures. Cardiac output remained more stable in extended sessions (change during HD4, -1.4±1.5 L/min; during HDF4, -1.6±1.0 L/min; during HD8, -0.4±0.9 L/min [P=0.02 vs. HDF4]; and during HDF8, -0.5±0.8 L/min [P=0.06 vs. HD4; P=0.03 vs. HDF4), in line with the decreased relative blood volume slope in long dialysis. No differences in microvascular density were found. Energy transfer rates were comparable (HD4, 13.3±4.7 W; HDF4, 16.2±5.6 W; HD8, 14.2±6.0 W; and HDF8, 14.5±4.3 W). Small-molecule and phosphate removal were superior during long treatments. β2-Microglobulin and fibroblast growth factor 23 (FGF-23) reduction ratios were highest in HDF8. Small sample size, only acute effects were studied. Treatment time, and not modality, was the determinant for the hemodynamic response. HDF significantly improved removal of middle molecules, with superior results in extended HDF.

O17 IMPACT OF ANTICOAGULANT THERAPY ON UPPER GASTROINTESTINAL BLEEDING (UGI) IN PATIENTS WITH LIVER CIRRHOSIS. RESULTS FROM A RETROSPECTIVE MULTICENTRIC CASE–CONTROL STUDY

Background and Aims: Portal hypertension leads to most complication of cirrhosis. Most complications are ameliorated by beta-blockers. Acute hemodynamic response is a recent modality of determining HVPG response. Aims: We aimed to assess the acute effect of Carvedilol on HVPG and its impact on outcome in cirrhotics over a 6-month period. Methods: Patients requiring beta-blocker therapy were subjected to HVPG measurement. After HVPG they were given Tab. Carvedilol 25mg and repeat HVPG performed after one hour. Acute responders (defined as a HVPG 10%. There were no baseline differences between two groups. On follow-up, complications like ascites and hepatic encephalopathy were significantly less common in acute responder group (p 0.05). Repeat HVPG after a median period of 6 months performed in 41 of 49 patients in the acute responder group. Out of 41 patients 35 (85%) patients were still responders (long term responders) and 6 (15%) patient were non long term responders. Conclusions: Determination of acute response to carvedilol is a convenient and rapid way to identify responders. It is an excellent prognostic marker as acute responders develop less complications.

Does Acute Hemodynamic Response to Carvedilol in Hepatic Venous Pressure Gradient Predicts Morbidity and Mortality in Cirrhosis? Prospective Study

Background: Portal hypertension leads to most of the complication of cirrhosis: both bleeding and non-bleeding. Most complications due to portal hypertension can be ameliorated by β-blockers in those who are hemodynamic responders. To identify hemodynamic responder, a repeat hepatic venous pressure gradient (HVPG) is required 4–6 weeks after initiation of beta-blocker therapy. Acute hemodynamic response is a recent modality of determining HVPG response immediately during the baseline HVPG by giving high dose of injectable or oral beta-blocker. Aims: To assess the acute effect of Carvedilol on HVPG and its impact on outcome in cirrhotics over a 6-month period of follow up. Patients and Methods: Patients requiring β-blocker therapy, for primary (25/69) or secondary (44/69) prevention of variceal bleeding, were subjected to HVPG measurement. Acute Responder were defined as HVPG <12 mmHg or >10% fall in HVPG from baseline. Immediately after HVPG they were given Tab. Carvedilol 25 mg and a repeat HVPG was performed after one hour. On the basis of hemodynamic response 2 groups were made, Acute responders and non-responders. Both these groups were followed for 6 months. A repeat HVPG was done in acute responder group after 6 month. Both these group of patients were offered standard medical therapy with beta-blocker (Carvedilol) and regular EVL. All complications, hospitalization and outcome of patient noted at the end of 6 month. Results: Out of 69 patients, 49 (71%) patients showed acute reduction in HVPG of >10% after oral Carvedilol. There were no baseline differences between the two groups. On follow-up, complications like ascites was significantly less common in acute responder group as compared to non-responder group (P < 0.001). However, there was no statistically significant difference in mortality between acute responder and non-responder groups (P > 0.05). Repeat HVPG after a median period of 6 months could be performed in 41 of 49 patients in the acute responder group, while 2 patients was not willing for a repeat HVPG and 6 patients had died during this period. Out of 41 patients 35 (85%) patients were still responders (long term responders) and 6 (15%) patient were non long term responders. Conclusions: Determination of acute response to carvedilol is not only a convenient and rapid way to identify beta-blocker hemodynamic responders; it also is an excellent prognostic marker as acute responders develop less portal hypertensive complication like ascites than non-responders on beta-blocker therapy. Also the most of acute responders are found to be longstanding responder. Keywords: HVPG; portal hypertension; cirrhosis; esophageal varices

The Effect of Left Ventricular Electrical Delay on the Acute Hemodynamic Response with Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) improves hemodynamic function, as well as reduces hospitalizations and mortality among patients with systolic dysfunction, QRS prolongation, and heart failure. The magnitude of the hemodynamic response is associated with improved outcomes, so optimization of this parameter is a goal of therapy. The purpose of this study was to evaluate the effect of left ventricular (LV) electrical delay, as assessed by the QLV interval, on the acute hemodynamic response to CRT. This study included 31 patients undergoing biventricular ICD placement. At implant, invasive LV dP/dt was measured by a micromanometer catheter during biventricular (BV) or LV only pacing. Both atrial sensing (AS) and atrial pacing (AP) modes were evaluated at 5 different AV delays, tested in randomized order. The QLV interval was measured at the LV pacing site. Compared with intrinsic rhythm, CRT increased LV dP/dtmax by 9.5 ± 8.8% with BV pacing and 10.0 ± 9.2% with LV pacing (P = 0.38) during AS. With AP, CRT increased LV dP/dtmax by 16.0 ± 10.8% and 15.3 ± 11.1%, respectively (P = 0.47). QLV was strongly correlated with the hemodynamic response in all pacing configurations. Multivariate analysis showed that with BV pacing QLV was an independent predictor of the hemodynamic response with a 1.7% increase in %LV dP/dt for every 10 milliseconds prolongation of QLV. LV electrical delay is a strong predictor of the acute hemodynamic response to CRT. This relationship is independent of pacing mode.

A comparison of left ventricular endocardial, multisite, and multipolar epicardial cardiac resynchronization: an acute haemodynamic and electroanatomical study

Alternative forms of cardiac resynchronization therapy (CRT), including biventricular endocardial (BV-Endo) and multisite epicardial pacing (MSP), have been developed to improve response. It is unclear which form of stimulation is optimal. We aimed to compare the acute haemodynamic response (AHR) and electrophysiological effects of BV-Endo with MSP via two separate coronary sinus (CS) leads or a single-quadripolar CS lead. Fifteen patients with a previously implanted CRT system received a second temporary CS lead and left ventricular (LV) endocardial catheter. A pressure wire and non-contact mapping array were placed into the LV cavity to measure LVdP/dtmax and perform electroanatomical mapping. Conventional CRT, BV-Endo, and MSP were then performed (MSP-1 via two epicardial leads and MSP-2 via a single-quadripolar lead). The best overall AHR was found using BV-Endo pacing with a 19.6 ± 13.6% increase in AHR at the optimal endocardial site over baseline (P < 0.001). There was an increase in LVdP/dtmax with MSP-1 and MSP-2 compared with conventional CRT, but this was not statistically significant. Biventricular endocardial pacing from the optimal site was significantly superior to conventional CRT (P = 0.039). The AHR achieved when BV-Endo pacing was highly site specific. Within individuals, the best pacing modality varied and was affected by the underlying substrate. Left ventricular activation times did not predict the optimal haemodynamic configuration. Biventricular endocardial pacing and not MSP was superior to conventional CRT, but was highly site specific. Within individuals, however, different methods of stimulation are optimal and may need to be tailored to the underlying substrate.

Fusion‐Optimized Intervals (FOI): A New Method to Achieve the Narrowest QRS for Optimization of the AV and VV Intervals in Patients Undergoing Cardiac Resynchronization Therapy

Optimization of atrioventricular (AV) and interventricular (VV) intervals may improve cardiac resynchronization therapy (CRT) response but is a complex task. Fusion with intrinsic conduction may increase the benefit of CRT. The aim was to describe fusion-optimized intervals (FOI), a new method of optimizing CRT based on QRS duration. Seventy-six consecutive patients with preserved AV conduction who received CRT were prospectively included. The AV interval was optimized by searching the narrowest QRS obtained within the fusion band during left ventricular (LV) pacing. The VV interval was then adjusted, comparing QRS duration in simultaneous biventricular, LV preexcitation (-30 milliseconds), right ventricular (RV) preexcitation (-30 milliseconds) and LV-only pacing. A substudy in 31 patients evaluated the invasive LV +dP/dtmax . The best fusion-optimized AV interval was 136 ± 30 milliseconds during atrial sensing and 192 ± 35 milliseconds during atrial pacing. The best QRS was obtained with simultaneous biventricular pacing in 28 patients (37%), LV preexcitation in 22 (29%), LV-only in 20 (26%), and RV preexcitation in 6 (8%). Baseline QRS was shortened more by FOI (59 ± 19 milliseconds) than by nominal settings (40 ± 21 milliseconds; P < 0.001). Sixty-five patients (86%) showed >10% shortening of the baseline QRS with FOI; none prolonged the QRS duration by FOI compared to nominal settings. All echocardiographic asynchrony parameters were corrected by FOI. Baseline +dP/dtmax improvement was greater in FOI (127 ± 95 mmHg/seconds) than in nominal settings (102 ± 71 mmHg/seconds; P = 0.05). The FOI method is feasible, further reduces QRS duration, and improves acute hemodynamic response compared to nominal programming of CRT.

The Hemodynamic Effects of Dexmedetomidine and Esmolol in Electroconvulsive Therapy

Acute hemodynamic responses, including transient hypertension and tachycardia, to electroconvulsive therapy (ECT) predispose vulnerable patients to significant cardiovascular complications. Many drugs have been used in an attempt to attenuate these responses. To date, no comparative study of the acute hemodynamic effects of dexmedetomidine and esmolol in ECT has been published. Hence, this retrospective study aimed to compare the effects of dexmedetomidine and esmolol on acute hemodynamic responses in patients undergoing ECT. The anesthesia records for 66 patients who underwent a total of 198 ECT treatments performed between July 2009 and January 2010 were analyzed retrospectively. For each case, 1 seizure with 1-mg/kg propofol as control (group C), 1 seizure with 1-μg/kg dexmedetomidine combined with propofol (group D; total volume, 30 mL for 10 minutes), and 1 seizure with 1-mg/kg esmolol combined with propofol were compared (group E; total volume, 30 mL for 10 minutes). Anesthesia was induced with 1-mg/kg propofol, and then intravenous succinylcholine, 0.5-mg/kg, was administered. Heart rates and systolic and mean blood pressures were recorded at baseline (T0) and 1, 3, and 10 minutes after the seizure (T1, T2, and T3, respectively). The electroencephalographic (EEG) tracing motor seizure duration, and recovery times (spontaneous breathing, eye opening, and obeying commands) were recorded. The baseline hemodynamic measurements were similar between the groups. Heart rates at T1, T2, and T3 were lower in group D than those in groups E and C (P < 0.05). Systolic blood pressures at T1, T2, and T3 were lower in group D than those in groups C (P < 0.05). In addition, systolic blood pressure at T3 was lower in group D than that in group E (P < 0.05). The mean blood pressure at T3 was significantly lower in group D than those in groups E and C (P <0.05). The electroencephalographic tracing, motor seizure durations, and recovery times were similar between the groups. Dexmedetomidine administration before anesthesia induction reduced the acute hemodynamic response compared with esmolol administration in the early period of ECT. Therefore, dexmedetomidine may be effective in preventing acute hemodynamic responses to ECT.

Fusion of electrical wave fronts in cardiac resynchronization therapy predicts response: an acute pressure-volume loop study

Purpose: In cardiac resynchronisation therapy (CRT), the contribution of right ventricular (RV) stimulation to overall pump function remains controversial. Recent research suggests that in patients with left bundle branch block, eligible for CRT, optimal hemodynamic benefit can be obtained by fusion of the intrinsic (right bundle branch (RBB)) wave front and the invoked wave front of left ventricular (LV) pacing. RV stimulation would only be necessary in patients with long intrinsic AV-delays since in such cases fusion with the intrinsic RBB wave front would compromise optimal AV-delay. To evaluate this hypothesis, we conducted acute hemodynamic measurements in CRT patients with varying AV-delays during LV only and biventricular (Biv) pacing. Methods: Patients eligible to CRT were included. Prior to CRT implantation, patients underwent a temporary pacing procedure. Temporary leads were placed in the right atrium, RV and at the posterolateral wall, and a conductance catheter was used to acquire left ventricular pressure and volume data. Stroke work (SW) and dP/dtmax were used to assess acute hemodynamic response during RV, LV and Biv pacing. Pacing was performed with a fixed AV-delay of 100ms. Analyses were done for the total study population, as well as for a normal AV-delay and first degree AV-block group. Results: Fifty-seven patients were included (37 (65%) males, age 67±10 years, LVEF 22±13%, QRS 154±21ms, ischemic cardiomyopathy 35 (61%) patients, AV-delay 189±34ms, 18 (32%) first degree AV-block). A positive correlation was observed between AV-delay and SW response to LV only pacing (R2 = 0.08, p = 0.032). No correlation was found during Biv pacing nor in dP/dtmax response. No significant differences were found in SW and dP/dtmax response between LV only and biv pacing in the normal AV-delay group (mean 170±18ms) (ΔSW 35±45% vs 31±50%, p=0.415; Δ dP/dtmax 8±18% vs 12±25%, p=0.258, respectively) and the first degree AV-block group (mean 230±23ms) (ΔSW 45±43% vs 30±46%, p=0.124; Δ dP/dtmax 7±14% vs 5±27%, p=0.652, respectively). Conclusion: The present study revealed that a longer AV-delay was positively correlated with SW response during LV, possibly due to AV optimisation. No differences in acute hemodynamic response were found between both pacing modalities in the normal and first degree AV-block group, suggesting that wave front fusion either by biventricular pacing or by fusion of LV pacing and intrinsic conduction is of minor importance.

Acute haemodynamic response to cardiac resynchronisation therapy is greater in patients with chronic right ventricular pacing compared to patients with intrinsic bundle branch block

Acute haemodynamic response to cardiac resynchronisation therapy is greater in patients with chronic right ventricular pacing compared to patients with intrinsic bundle branch block

Acute changes in electromechanical parameters during different pacing configurations using a quadripolar left ventricular lead

Quadripolar left ventricular (LV) leads allow for several pacing configurations in candidates for cardiac resynchronization therapy (CRT). Whether different pacing configurations may affect LV dyssynchrony and systolic function is not completely known. We aimed to evaluate the acute effects of different pacing vectors on LV electromechanical parameters in patients implanted with a quadripolar LV lead. In this two-centre study, within 1 month of implantation 21 CRT patients (65 ± 8 years, 76 % men, 38 % ischemic) receiving a quadripolar LV lead (Quartet 1458Q, St Jude Medical) underwent LV capture threshold assessment, intracardiac electrogram optimization, and two-dimensional echocardiography during four pacing configurations: D1-P4, P4-RV coil, D1-RV coil, and P4-M2. LV dyssynchrony and contractile function were expressed by septal-to-lateral delay and global longitudinal strain (GLS). LV capture threshold varied between the configurations (P < 0.001), showing higher values in the configurations P4-RV coil and P4-M2. Septal-to-lateral delay decreased in the configurations D1-P4 and D1-RV coil (P = 0.003 and P = 0.033 vs. spontaneous rhythm, respectively). GLS improved significantly vs. spontaneous rhythm only in the configuration D1-P4 (from -8.6 ± 3.5 to -11.0 ± 3.2 %, P = 0.001). Accordingly, an increase in stroke volume and a decrease in mitral regurgitation were observed in the configuration D1-P4 (P ≤ 0.001 vs. spontaneous rhythm). In CRT patients receiving a quadripolar LV lead, significant variations in electromechanical parameters were observed by changing pacing vector. Individually targeting the optimal pacing site may enhance the acute haemodynamic response to CRT.

Vector Selection of a Quadripolar Left Ventricular Pacing Lead Affects Acute Hemodynamic Response to Cardiac Resynchronization Therapy: A Randomized Cross-Over Trial

BackgroundA suboptimal left ventricular (LV) pacing site may account for non-responsiveness of patients to cardiac resynchronization therapy (CRT). The vector selection of a novel quadripolar LV pacing lead, which was mainly developed to overcome technical issues with stimulation thresholds and phrenic nerve capture, may affect hemodynamic response, and was therefore assessed in this study. (German Clinical Trials Register DRKS00000573).Methods and ResultsHemodynamic effects of a total of 145 LVPCs (9.1 per patient) of CRT devices with a quadripolar LV lead (Quartet™, St. Jude Medical) were assessed in 16/20 consecutive patients by invasive measurement of LV+dP/dtmax at an invasively optimized AV-interval in random order. Optimal (worst) LVPCs per patient were identified as those with maximal (minimal) %change in LV+dP/dtmax (%ΔLV+dP/dtmax) as compared to a preceding baseline. LV+dP/dtmax significantly increased in all 145 LVPCs (p<0.0001 compared to baseline) with significant intraindividual differences between LVPCs (p<0.0001). Overall, CRT acutely augmented %ΔLV+dP/dtmax by 31.3% (95% CI 24%–39%) in the optimal, by 21.3% (95% CI: 15%–27%) in the worst and by 28.2% (95% CI: 21%–36%) in a default distal LVPC. This resulted in an absolute additional acute increase in %ΔLV+dP/dtmax of 10.0% (95% CI: 7%–13%) of the optimal when compared to the worst (p<0.0001), and of 3.1% (95% CI: 1%–5%) of the optimal when compared to the default distal LVPC (p<0.001). Optimal LVPCs were not programmable with a standard bipolar lead in 44% (7/16) of patients.ConclusionThe pacing configuration of a quadripolar LV lead determinates acute hemodynamic response. Pacing in the individually optimized configuration gives rise to an additional absolute 10% increase in %ΔLV+dP/dtmax when comparing optimal and worst vectors.

The relationship between head injury severity and hemodynamic response to tracheal intubation

The acutely injured brain is sensitive to fluctuations in blood pressure. During tracheal intubation, airway stimulation provokes acute surges in blood pressure that have the potential to cause further harm in patients with intracranial pathology. Although reduced consciousness is thought to suppress airway reflexes, its influence on these hemodynamic reflexes is unknown.We aimed to investigate the relationship between head injury severity and hemodynamic response to laryngoscopy and intubation. This retrospective observational study included 97 consecutive patients with head injuries who underwent prehospital tracheal intubation by a physician-led helicopter emergency medical service. The primary outcome was the acute hemodynamic response to the procedure. Secondary outcomes included the incidence of serious intracranial pathology and mortality. A hypertensive response to laryngoscopy and tracheal intubation occurred in 80% of patients. In 11% of patients, blood pressure increased by ≥100%. The hemodynamic response was attenuated with increasing head injury severity but unpredictably and not to clinically acceptable levels. The incidence of serious intracranial bleeding (61%) and raised intracranial pressure (22%) was high in patients with head injuries, requiring tracheal intubation. A clinically significant hemodynamic response to laryngoscopy and intubation is common in patients with head injuries and is not effectively attenuated by increasing head injury severity. The need to attenuate the hemodynamic response should be assessed independently of head injury severity. Therapeutic study, level III.

THE INFLUENCE OF RIGHT VENTRICULAR PACING ON RESPONSE TO BIVENTRICULAR PACING: AN ACUTE PRESSURE-VOLUME LOOP STUDY

Background: Cardiac resynchronization therapy (CRT) is an established therapy for end-stage heart failure. It is currently recommended to position the left ventricular (LV) lead at the postero-lateral (PL) wall. However, the position of the right ventricular (RV) lead remains controversial, since it may be associated with adverse hemodynamic effects. This may partly explain non-response to CRT. We hypothesized that RV pacing during biventricular pacing signiicantly modulates response. We studied the acute invasive hemodynamic response of RV, LV and biventricular pacing.

Prediction of long‐term outcome of cardiac resynchronization therapy by acute pressure–volume loop measurements

Invasive assessment of acute haemodynamic response to biventricular pacing has been proposed as a tool to determine individual response and to optimize the effects of CRT. However, the long-term results of this approach have been poorly studied. The present study relates acute haemodynamic effects of CRT to long-term outcome. Forty-one patients were analysed in the present study. During temporary biventricular pacing before implantation, acute changes in LV pump function were assessed by pressure-volume loop measurements and related to long-term response after CRT. In the study population [30 (71%) men, NYHA class 2.9 ± 0.4, EF 28 ± 7%, QRS 150 ± 25 ms], baseline mean stroke work (SW) and dP/dt(max) were 4.6 ± 2.6 L × mmHg and 874 ± 259 mmHg/s, respectively. During biventricular pacing, mean SW and dP/dt(max) increased significantly by 43 ± 39% (+ 2.2 ± 2.4 L × mmHg, P < 0.001) and 13 ± 18% (+ 96 ± 136 mmHg/s, P < 0.001), respectively. In long-term responders (n = 29, 71%) compared with non-responders (n = 12, 29%), the acute increase in SW was significantly higher (+57 ± 33% vs. + 10 ± 30%, P < 0.001), whereas the acute increase in dP/dt(max) was not significantly different between responders and non-responders (+ 15 ± 18% vs. 6 ± 15%, P = 0.139). Receiver operating characteristic (ROC) curve analysis indicated that SW was superior to dP/dt(max), QRS duration and LV dyssynchrony in prediction of response to CRT. A cut-off value for SW of 20% yielded a sensitivity of 90% and specificity of 75% to predict reverse remodelling at 6 months. Invasive assessment of acute haemodynamics is a reliable tool to determine individual response to CRT. An acute increase in SW predicts long-term response to CRT with a higher accuracy than an acute increase in dP/dt(max), baseline QRS duration, and degree of LV mechanical dyssynchrony.

Acute haemodynamic comparison of multisite and biventricular pacing with a quadripolar left ventricular lead

Pacing from multiple sites in the left ventricle (LV) may bring about further resynchronization of the diseased heart compared with biventricular (BiV) pacing. We compared acute haemodynamic response (LV dP/dtmax) of multisite and BiV pacing using a quadripolar LV lead. In 21 patients receiving cardiac resynchronization therapy, a quadripolar LV lead and conventional right atrial and ventricular leads were connected to an external pacing system. A guidewire pressure sensor was placed in the LV for continuous dP/dt measurement. Four multisite pacing configurations were tested three times each and compared with BiV pacing using the distal LV electrode. Nineteen patients had useable haemodynamic data. Median increase in LV dP/dtmax with BiV vs. atrial-only pacing was 8.2% (interquartile range 2.3%, 15.7%). With multisite pacing using distal and proximal LV electrodes, median increase in LV dP/dtmax was 10.2% compared with atrial-only pacing (interquartile range 6.1%, 25.6%). In 16 of 19 patients (84%), two or more of the four multisite pacing configurations increased LV dP/dtmax compared with BiV pacing. Overall, 72% of all tested configurations of multisite pacing produced greater LV dP/dtmax than obtained with BiV pacing. Pacing from most distal and proximal electrodes was the most common optimal configuration, superior to BiV pacing in 74% of patients. In the majority of patients, multisite pacing improved acute systolic function further compared with BiV pacing. Pacing with the most distal and proximal electrodes of the quadripolar LV lead most commonly yielded greatest LV dP/dtmax.

Right ventricular lead adjustment in cardiac resynchronization therapy and acute hemodynamic response: a pilot study

Optimal left ventricular (LV) lead position has emerged as an important determinant of response after cardiac resynchronization therapy (CRT). Comparatively, strategy for right ventricular (RV) lead optimization remains uncertain. Three variations of RV lead position (apex, mid-septal, and high septal) were tested in seven consecutive patients. At each location, intra-procedural measurement of LV lead electrical delay (LVLED) was obtained during intrinsic rhythm and RV pacing (RV-LVLED). Simultaneous cardiac output assessment was performed using the LiDCO™ (lithium chloride indicator dilution) system. Final RV lead location was selected based on best-measured cardiac output. Clinical and echocardiographic outcomes were assessed at baseline and 6 months. Adjustment of RV lead position after securing a LV lead site led to an incremental change of 30 ± 18 % (range, 7-52 %) in the cardiac index (CI). There was substantial variation in acute hemodynamic response (∆CI, 14 ± 13 %; range, 3-41 %) seen with pacing from each patient's worst to best RV lead position; no single RV lead position emerged as optimal across all patients. Paced RV-LVLED was not correlated with percent change in CI (r = 0.18; p = NS). LV ejection fraction (LVEF) increased significantly (28 ± 4 to 40 ± 8 %, p = 0.006) at 6 months. LVLED measured during intrinsic rhythm, but not during RV pacing, correlated with percent change in LVEF (r = 0.88, p = 0.02). RV lead position adjustment can be used to enhance acute hemodynamic response during CRT. Measurement of paced RV-LVLED, however, does not reliably predict change in cardiac output.