Invasive left ventricle pressure-volume analysis: overview and practical clinical implications.

Ventricular pressure-volume (PV) analysis is the reference method for the study of cardiac mechanics. Advances in calibration algorithms and measuring techniques brought new perspectives for its application in different research and clinical settings. Simultaneous PV measurement in the heart chambers offers unique insights into mechanical cardiac efficiency. Beat to beat invasive PV monitoring can be instrumental in the understanding and management of heart failure, valvular heart disease, and mechanical cardiac support. This review focuses on intra cardiac left ventricular PV analysis principles, interpretation of signals, and potential clinical applications.

Determination of cardiac output from pulse pressure contour during intra-aortic balloon pumping in patients with low ejection fraction.

Evaluation of a new Windkessel model based pulse contour method (WKflow) to calculate stroke volume in patients undergoing intra-aortic balloon pumping (IABP). Preload changes were induced by vena cava occlusions (VCO) in twelve patients undergoing cardiac surgery to vary stroke volume (SV), which was measured by left ventricular conductance volume method (SVlv) and WKflow (SVwf). Twelve VCO series were carried out during IABP assist at a 1:2 ratio and seven VCO series were performed with IABP switched off. Additionally, SVwf was evaluated during nine episodes of severe arrhythmia. VCO's produced marked changes in SV over 10-20 beats. 198 paired data sets of SVlv and SVwf were obtained. Bland-Altman analysis for the difference between SVlv and SVwf during IABP in 1:2 mode showed a bias (accuracy) of 1.04 ± 3.99 ml, precision 10.9% and limits of agreement (LOA) of - 6.94 to 9.02 ml. Without IABP bias was 0.48 ± 4.36 ml, precision 11.6% and LOA of - 8.24 to 9.20 ml. After one thermodilution calibration of SVwf per patient, during IABP the accuracy improved to 0.14 ± 3.07 ml, precision to 8.3% and LOA to - 6.00 to + 6.28 ml. Without IABP the accuracy improved to 0.01 ± 2.71 ml, precision to 7.5% and LOA to - 5.41 to + 5.43 ml. Changes in SVlv and SVwf were directionally concordant in response to VCO's and during severe arrhythmia. (R2 = 0.868). The SVwf and SVlv methods are interchangeable with respect to measuring absolute stroke volume as well as tracking changes in stroke volume. The precision of the non-calibrated WKflow method is about 10% which improved to 7.5% after one calibration per patient.

Real-time left ventricular pressure-volume loops during percutaneous mitral valve repair with the MitraClip system.

BACKGROUND: Percutaneous mitral valve repair with the MitraClip device has emerged as an alternative to surgery for treating severe mitral regurgitation. However, its effects on left ventricular loading conditions and contractility have not been investigated yet. METHODS AND RESULTS: Pressure-volume loops were recorded throughout the MitraClip procedure using conductance catheter in 33 patients (mean age, 78±10 years) with functional (45%), degenerative (48%), or mixed (6%) mitral regurgitation. Percutaneous mitral valve repair increased end-systolic wall stress (WSES; from [median] 184 mm Hg [interquartile range (IQR), 140-200 mm Hg] to 209 mm Hg [IQR, 176-232 mm Hg]; P=0.001) and decreased end-diastolic WS (WSED; from 48 mm Hg [IQR, 28-58 mm Hg] to 34 mm Hg [IQR, 21-46 mm Hg]; P=0.005), whereas the end-systolic pressure-volume relationship was not significantly affected. Conversely, cardiac index increased (from 2.6 L·min(-1)·m(-2) [IQR, 2.2-3.0 L·min(-1)·m(-2)] to 3.2 L·min(-1)·m(-2) [IQR, 2.6-3.8 L·min(-1)·m(-2)]; P<0.001) and mean pulmonary capillary wedge pressure decreased (from 15 mm Hg [IQR, 12-20 mm Hg] to 12 mm Hg [IQR, 10-13 mm Hg]; P<0.001). Although changes in WSES were not correlated with changes in cardiac index, changes in WSED correlated significantly with changes in mean pulmonary capillary wedge pressure (r=0.63, P<0.001). Total mechanical energy assessed by the pressure-volume area remained unchanged, resulting in a more favorable index of forward output (cardiac index) to mechanical energy (pressure-volume area) after mitral valve repair. On follow-up (153±94 days), New York Heart Association functional class was reduced from 2.9±0.6 to 1.9±0.5 (P<0.001) at 3 months, and echocardiographic follow-up documented a stepwise reduction in end-diastolic volume (from 147 mL [IQR, 95-191 mL] to 127 mL [IQR, 82-202 mL]; P=0.036). CONCLUSIONS: Percutaneous mitral valve repair improves hemodynamic profiles and induces reverse left ventricular remodeling by reducing left ventricular preload while preserving contractility. In nonsurgical candidates with compromised left ventricular function, MitraClip therapy could be considered an alternative to surgical mitral valve repair.

Effect of Next Generation Pulsatile Mechanical Circulatory Support on Cardiac Mechanics: The PULSE Trial.

OBJECTIVES: To describe hemodynamic effects of iVAC2L mechanical circulatory support (MCS). BACKGROUND: MCS is increasingly used in the context of high-risk percutaneous coronary intervention (PCI). The effect of the pulsatile iVAC2L MCS on left ventricular loading conditions and myocardial oxygen consumption (MVO2) is unknown. METHODS: This prospective single-arm two-center study included 29 patients who underwent high-risk PCI with iVAC2L MCS using simultaneous invasive pulmonary pressure monitoring and left ventricular pressure-volume analysis. Hemodynamic recordings were performed during steady state conditions with MCS off and on before and after PCI. Pressure-volume variations were analyzed to denote responders and non-responders. RESULTS: The mean age was 74 (IQR: 70-81) years and the mean SYNTAX score was 31 ± 8.3. Left ventricular unloading with iVAC2L MCS was demonstrated in 22 out of 27 patients with complete PV studies. Patients with moderate or severe mitral regurgitation or presenting with acute coronary syndrome (ACS) had higher filling pressures and volumes and were most responsive to iVAC2L unloading (9/10 patients with moderate or severe MR and 11/11 patients with ACS). Pulsatile MCS activation reduced MAP (-4%), SBP (-9%), ESP (-11%), ESV (-15%) and EDV (-4%) among responders but not among non-responders. Responders experienced significant reductions in afterload (Ea: -19%) with increases in stroke volume (+11%) and cardiac output (+11%). CONCLUSIONS: Pulsatile iVAC2L MCS in patients with advanced coronary artery disease at high to prohibitive operative risk resulted in LV unloading and reduced myocardial oxygen consumption particularly in patients with ACS or significant MR with higher filling pressures at baseline. CLINICAL TRIAL REGISTRATION: NCT03200990.

Invasive Real Time Biventricular Pressure-Volume Loops to Monitor Dynamic Changes in Cardiac Mechanoenergetics During Structural Heart Interventions: Design and Rationale of a Prospective Single-Center Study.

Background: Transcatheter valvular interventions affect cardiac and hemodynamic physiology by changing ventricular (un-)loading and metabolic demand as reflected by cardiac mechanoenergetics. Real-time quantifications of these changes are scarce. Pressure-volume loop (PVL) monitoring appraises both load-dependent and load-independent compounds of cardiac physiology including myocardial work, ventricular unloading, and ventricular-vascular interactions. The primary objective is to describe changes in physiology induced by transcatheter valvular interventions using periprocedural invasive biventricular PVL monitoring. The study hypothesizes transcatheter valve interventions modify cardiac mechanoenergetics that translate into improved functional status at 1-month and 1-year follow-up. Methods: In this single-center prospective study, invasive PVL analysis is performed in patients undergoing transcatheter aortic valve replacement or tricuspid or mitral transcatheter edge-to-edge repair. Clinical follow-up is per standard of care at 1 and 12 months. This study aims to include 75 transcatheter aortic valve replacement patients and 41 patients in both transcatheter edge-to-edge repair cohorts. Results: The primary outcome is the periprocedural change in stroke work, potential energy, and pressure-volume area (mmHg mL-1). The secondary outcomes comprise changes in a myriad of parameters obtained by PVL measurements, including ventricular volumes and pressures and the end-systolic elastance-effective arterial elastance ratio as a reflection of ventricular-vascular coupling. A secondary endpoint associates these periprocedural changes in cardiac mechanoenergetics with functional status at 1 month and 1 year. Conclusions: This prospective study aims to elucidate the fundamental changes in cardiac and hemodynamic physiology during contemporary transcatheter valvular interventions.

Invasive Cardiomechanics During Transcatheter Edge-to-Edge Repair for Massive Tricuspid Regurgitation Using Biventricular Pressure-Volume Loop Monitoring.

Invasive pressure-volume loop analysis allows direct monitoring of changing intraventricular cardiac mechanics during structural heart interventions. Our aim was to illustrate changes in right and left ventricular mechanics during transcatheter edge-to-edge tricuspid repair for severe tricuspid regurgitation. (Level of Difficulty: Advanced.).

Physiological Impact of Afterload Reduction on Cardiac Mechanics and Coronary Hemodynamics Following Isosorbide Dinitrate Administration in Ischemic Heart Disease.

Understanding the cardiac-coronary interaction is fundamental to developing treatment strategies for ischemic heart disease. We sought to examine the impact of afterload reduction following isosorbide dinitrate (ISDN) administration on LV properties and coronary hemodynamics to further our understanding of the cardiac-coronary interaction. Novel methodology enabled real-time simultaneous acquisition and analysis of coronary and LV hemodynamics in vivo using coronary pressure-flow wires (used to derive coronary wave energies) and LV pressure-volume loop assessment. ISDN administration resulted in afterload reduction, reduced myocardial demand, and increased mechanical efficiency (all P<0.01). Correlations were demonstrated between the forward compression wave (FCW) and arterial elastance (r=0.6) following ISDN. In the presence of minimal microvascular resistance, coronary blood flow velocity exhibited an inverse relationship with LV elastance. In summary this study demonstrated a reduction in myocardial demand with ISDN, an inverse relationship between coronary blood flow velocity and LV contraction-relaxation and a direct correlation between FCW and arterial elastance. The pressure volume-loop and corresponding parameters b The pressure volume loop before (solid line) and after (broken line) Isosorbide dintrate.

Impact of coronary artery disease on contractile function and ventricular-arterial coupling during exercise: Simultaneous assessment of left-ventricular pressure-volume and coronary pressure and flow during cardiac catheterization.

Coronary artery disease (CAD) can adversely affect left ventricular (LV) performance during exercise by impairment of contractile function in the presence of increasing afterload. By performing invasive measures of LV pressure-volume and coronary pressure and flow during exercise, we sought to accurately measure this with comparison to the control group. Sixteen patients, with CCS class >II angina and CAD underwent invasive simultaneous measurement of left ventricular pressure-volume and coronary pressure and flow velocity during cardiac catheterization. Measurements performed at rest were compared with peak exercise using bicycle ergometry. The LV contractile function was measured invasively using the end-systolic pressure-volume relationship, a load independent marker of contractile function (Ees). Vascular afterload forces were derived from the ratio of LV end-systolic pressure to stroke volume to generate arterial elastance (Ea). These were combined to assess cardiovascular performance (ventricular-arterial [VA] coupling ratio [Ea/Ees]). Eleven patients demonstrated flow-limiting (FL) CAD (hyperemic Pd/Pa <0.80; ST-segment depression on exercise); five patients without flow-limiting (NFL) CAD served as the control group. Exercise in the presence of FL CAD was associated impairment of Ees, increased Ea, and deterioration of VA coupling. In the control cohort, exercise was associated with increased Ees and improved VA coupling. The backward compression wave energy directly correlated with the magnitude contraction as measured by dP/dTmax (r = 0.88, p = 0.004). This study demonstrates that in the presence of flow-limiting CAD, exercise to maximal effort can lead to impairment of LV contractile function and a deterioration in VA coupling compared to a control cohort.

New-generation mechanical circulatory support during high-risk PCI: a cross-sectional analysis.

AIMS: The aim of the study was to establish the value of new-generation mechanical circulatory support (MCS) devices such as HeartMate PHP, Impella CP and PulseCath iVAC2. METHODS AND RESULTS: We retrospectively analysed all consecutive elective high-risk PCI procedures performed in the Erasmus Medical Center (2011-2018) in order to compare MCS protected and unprotected patients. The primary endpoint was a composite of procedure-related adverse events including death (<24 hours), cardiac arrest, need for vasopressors, rescue MCS, endotracheal intubation and limb ischaemia with need for surgery. Secondary endpoints included 30-day survival. A total of 198 elective high-risk PCI patients were included (69 [35%] MCS protected, 129 [65%] MCS unprotected). When compared with unprotected patients, MCS protected patients had a significantly worse left ventricular ejection fraction (LVEF) (25±10 vs 33±8%, p<0.01) and higher SYNTAX I score (33±11 vs 24±8, p<0.01). The primary endpoint occurred in 26 (20%) of the unprotected patients and in 6 (9%) of the MCS protected patients (OR 0.38, 95% CI: 0.15-0.97, p=0.04). Patients under 75 years of age, with a SYNTAX I score above 32 and with an LVEF below 30% showed most potential benefit from MCS. Survival during the first 24 hours after the procedure and at 30 days was significantly higher in MCS protected patients (100% vs 95%, p=0.04 at 24 hours, and 98% vs 87%, OR 10.32, 95% CI: 1.34-79.31, p=0.006 at 30 days). CONCLUSIONS: In a consecutive real-world cohort of high-risk PCI patients, protection with new-generation MCS resulted in better procedural outcomes despite worse EF and more complex coronary artery disease at baseline. Larger prospective studies are needed to confirm these findings.

Coherent averaging improves the evaluation of left ventricular dyssynchrony by conductance catheter.

OBJECTIVE: Coherent averaging is a technique to recover the response to repetitively applied stimuli when that response is embedded in random noise. We derived novel indices for left ventricular dyssynchrony estimation from volume-catheter signals using coherent averaging procedure: mechanical dyssynchrony (DYSCoh) internal flow fraction (IFFCoh) and mechanical dispersion (DISPCoh). The percentage power of non-repetitive components in the volume signals (ResTotAvg) was also estimated. The aims of the study were to evaluate the indices, characterizing repetitive and non-recurrent components of the conductance-volume signals, and to assess the ability of these indices to detect the changes in dyssynchrony induced by biventricular pacing (BIV). METHODS: We compared the results obtained in 20 heart failure patients indicated to BIV (HF Group) during spontaneous conduction with the results from 12 patients with preserved ventricular function (non-HF Group), and with those obtained during BIV. RESULTS: DISPCoh and ResTotAvg were significantly different in HF compared to non-HF group, and identified HF patients with high accuracy (area under curve at ROC analysis > 0.8). These indices also demonstrated significant differences after BIV (p = 0.047 and p = 0.037 respectively) and their baseline values correlated with the acute increase of stroke volume (r = 0.64 and r = 0.78, both with p < 0.005). CONCLUSIONS: Coherent averaging-based indices permit independent quantification and differentiation of repetitive components of ventricular dyssynchrony from non-recurrent mechanical non-uniformities, which seem associated with HF and conduction disturbances. These indices identified HF patients with high accuracy, and were able to describe the reversal of dyssynchrony caused by BIV and to predict the acute hemodynamic improvement.

Acute effects of His bundle pacing versus left ventricular and right ventricular pacing on left ventricular function.

Dual-chamber pacing with His bundle pacing has theoretical advantages over conventional right ventricular (RV) apical pacing. We compared indexes of left ventricular (LV) function during acute dual-chamber pacing from the His bundle and other RV and LV pacing sites. Twelve patients (6 men; 63 +/- 11 years) with a standard indication for electrophysiologic study were included. Average QRS duration was 100 +/- 19 ms. Ejection fraction was 48 +/- 15%. A pressure-volume catheter was positioned in the left ventricle through the femoral arterial access. Pressure-volume loops were collected during atrial (AAI) and dual-chamber overdrive pacing at 82 +/- 15 beats/min after 2 minutes of hemodynamic stabilization. Ventricular pacing catheter position was randomized between the RV apex, RV septal, and free wall portions of the outflow tract, LV free wall, and His bundle. His bundle capture was verified from surface electrocardiographic morphometry using standard criteria. Atrioventricular delay was set to the P wave-His duration -10 ms to minimize the effects of fusion (96 +/- 22 ms). LV only pacing, but not His pacing, resulted in improved stroke work and stroke volume compared with alternate site RV pacing. No changes in +dP/dt, LV end-systolic pressure. LV end-diastolic pressure, or cycle efficiency, were observed between RV pacing sites. In conclusion, acute His bundle pacing did not improve LV function compared with alternate site RV pacing and may be inferior to LV pacing.

Acute decrease of left ventricular mechanical dyssynchrony and improvement of contractile state and energy efficiency after left ventricular restoration.

OBJECTIVE: Surgical left ventricular restoration by means of endoventricular patch aneurysmectomy in patients with postinfarction aneurysm should result in acute improved left ventricular performance by decreasing mechanical dyssynchrony and increasing energy efficiency. METHODS: Nine patients with left ventricular postinfarction aneurysm were studied intraoperatively before and after ventricular restoration with a conductance volume catheter to analyze pressure-volume relationships, energy efficiency, and mechanical dyssynchrony. The end-systolic elastance was used as a load-independent index of contractile state. Left ventricular energy efficiency was calculated from stroke work and total pressure-volume area. Segmental volume changes perpendicular to the long axis were used to calculate mechanical dyssynchrony. Statistical analysis was performed with the paired t test and least-squares linear regression. RESULTS: Endoventricular patch aneurysmectomy reduced end-diastolic volume by 37% (P < .001), with unchanged stroke volume. Systolic function improved, as derived from increased +dP/dt(max), by 42% (P < .03), peak ejection rate by 28% (P < .02), and ejection fraction by 16% (P < .0002). Early diastolic function improved, as shown by reduction of -dP/dt(max) by 34% (P < .006) and shortened tau by 30% (P < .001). Left ventricular end-systolic elastance increased from 1.2 +/- 0.6 to 2.2 +/- 1 mm Hg/mL (P < .001). Left ventricular energy efficiency increased by 36% (P < .002). Left ventricular mechanical dyssynchrony decreased during systole by 33% (P < .001) and during diastole by 20% (P < .005). CONCLUSIONS: Left ventricular restoration induced acute improvements in contractile state, energy efficiency, and relaxation, together with a decrease in left ventricular mechanical dyssynchrony.

Surgical methods to reverse left ventricular remodeling in congestive heart failure.

In this review article, we describe the most common surgical procedures currently used to reverse or arrest remodeling of the left ventricle in patients with congestive heart failure (CHF). The selection of the appropriate operation in a patient is a complex decision-making process, rigorously based on pathophysiologic considerations. In this population, all factors affecting the surgical risk should be carefully evaluated preoperatively, and surgery should be recommended when definite benefits in survival and quality of life can be reasonably predicted. Quite often, patients with CHF require a combination of different procedures to address all the pathophysiologic components determining the clinical picture. In particular, in this review we describe the surgical restoration of the left ventricle, the isolated coronary artery bypass graft procedure, the correction of mitral regurgitation, diastolic support (from dynamic cardiomyoplasty to passive containment), and mechanical assist devices. Moreover, in the future, the role of surgery in the treatment of CHF will be strongly modified by the advent of gene therapy, cell therapy, and engineered artificial myocardial tissue.

Perioperative hemodynamic and geometric changes of the left ventricle during cardiomyoplasty in goats with dilated left ventricle.

OBJECTIVE: Clinical data have suggested the occurrence of temporary short-term deterioration of the heart following cardiomyoplasty. The purpose of this study was to monitor the short-term hemodynamic effects of cardiomyoplasty in a goat model of a dilated left ventricle, using conductance catheters (ie, pressure-volume loops) and cardiac output measurements. METHODS: Eight female goats underwent acute cardiomyoplasty 8 to 12 weeks after left ventricular (LV) dilatation was induced by a carotid jugular arteriovenous shunt. The cardiomyoplasty procedure was monitored using a Swan-Ganz catheter for cardiac output measurements and a 12-electrode (dual-field) conductance catheter to LV pressure-volume loops. RESULTS: After wrapping the heart with the latissimus dorsi muscle, there was a significant reduction in both cardiac output and LV end-diastolic volume (LVEDV) at 10 min. Partial recovery was observed 45 min later. CONCLUSION: A decrease in both cardiac output and LVEDV was observed following myocardial wrapping. This may explain some of the perioperative and postoperative morbidity and mortality observed following cardiomyoplasty.

Acute effects of beating heart coronary surgery on left ventricular performance.

BACKGROUND: The increasing use of off-pump bypass grafting (OPCABG), requires an evaluation of its effects on left ventricular (LV) performance. METHODS: In 8 patients with multivessel coronary disease who were undergoing to off-pump coronary artery bypass grafting, LV performance was analyzed from the pressure-volume (P-V) plane by the conductance catheter technique. Measurements were performed at base line, after the exposure of the vessels, after the application of the stabilization system, and at the end of the procedure. RESULTS: No significant changes in heart rate, LV end-systolic volume, LV end-diastolic pressure, mean pulmonary artery, and mean systemic blood pressure were observed in the various stages of the procedure. Cardiac index decreased during left anterior descending coronary artery grafting after application of the stabilizer with a concomitant decrease in LV end-diastolic volume, together with decreases in LV peak negative -dP/dt and increases in tau, indicating an impairment of LV relaxation but without a change in preload recruitable stroke work, indicating preserved LV contractile state. Exposure of posterior and lateral vessels induced a decrease in cardiac index and preload recruitable stroke work without a decrease in LV preload, indicating a decrease in LV contractile state together with a decrease in peak -dP/dt and increase in tau, indicating an impairment in LV relaxation CONCLUSIONS: Off-pump coronary artery bypass grafting can be performed without decreasing LV performance. Major cardiac displacement like that used for posterior and lateral exposure induces acutely significant decrease in LV contractile state.

Effects of chronic cardiomyoplasty on ventricular remodeling in a goat model of chronic cardiac dilatation: part 2.

BACKGROUND: Reduction of ventricular dilatation, rather than direct improvement of pump function, has been suggested to be the main working mechanism of dynamic cardiomyoplasty (CMP). This working mechanism was examined in the goat using a chronic cardiac dilatation model induced by the creation of a cervical arteriovenous shunt and submitted to passive and active CMP. METHODS: Fourteen female goats underwent surgical creation of a shunt between the left carotid artery and the jugular vein. Seven goats had no additional operation (control group). The other 7 goats (CMP group) underwent CMP approximately 8 weeks after the creation of the shunt. The wrapped left latissimus dorsi muscle was left unstimulated for 2 weeks, and subsequently stimulated electrically for a 3-month period, using a 1:4 muscle-to-heart contraction ratio. Hemodynamic measurements included heart catheterization and determination of left ventricular (LV) pressure-volume relations by means of the conductance catheter method at baseline, after 8 weeks (only in the CMP group), and after 5 months. Transthoracic echocardiography was performed just before opening the AV shunt and every 2 weeks thereafter. RESULTS: Significant ventricular enlargement, as well as persistent increase in filling pressures, were observed after 8 weeks. Animals in the control group dilated further beyond 2 months (LV end-diastolic diameter from 39 +/- 2 to 67 +/- 6 mm). In contrast, the ongoing LV dilatation process was stopped by passive CMP, and LV end-diastolic diameter significantly decreased after electrical activation of the wrapped skeletal muscle (from 63 +/- 7 to 42 +/- 6 mm). Cardiomyoplasty also significantly increased the slope of the end-systolic pressure-volume relation (elastance) when compared with pre-CMP values (from 0.9 +/- 0.2 to 1.7 +/- 0.5 mm Hg/mL), which indicated an improvement of the LV contractile state. No significant hemodynamic effects could be observed at the tuned stimulation settings on a beat-to-beat basis during electrical muscle stimulation. CONCLUSIONS: The contribution of CMP to LV dimension and contractility appeared to be either passive or active, and this study suggests the importance of stimulating the latissimus dorsi muscle to enhance the girdling effects of the wrapped latissimus dorsi muscle and to improve LV contractility.

Effects of acute dynamic cardiomyoplasty in a goat model of chronic ventricular dilatation: part 1.

BACKGROUND: The acute effects of cardiomyoplasty in an experimental model of chronic dilated heart have not been thoroughly investigated. Therefore, a model of chronic left ventricular (LV) dilatation was created to accurately determine actual changes shortly after passive and active wrapped skeletal muscle. METHODS: A carotid-jugular shunt model in 8 goats was used to induce progressive dilatation of the cardiac ventricles. Geometric modifications induced by the arteriovenous shunt were monitored by transthoracic echocardiography. After 8 weeks, cardiomyoplasty was performed, and the acute hemodynamic changes obtained with static cardiomyoplasty soon after the wrapping procedure were determined. Hence, hemodynamic variables recorded during assisted cardiac beats were then compared with data collected with unassisted cardiac beats using the conductance catheter method to generate pressure-volume loops. RESULTS: During electrical stimulation of the unconditioned skeletal muscle wrapped around the dilated left ventricle, a significant increase in stroke volume (117 +/- 48 mL versus 87 +/- 38 mL; p < 0.05) was observed. Early wrapped latissimus dorsi muscle activation also induced a reduction in LV end-systolic volume (from 51 +/- 28 mL to 27 +/- 14 mL; p < 0.05) when compared with unassisted LV contraction. CONCLUSIONS: In a chronic model of cardiac dilatation, acute dynamic cardiomyoplasty was shown to increase LV contractile performance and reduce LV volume. Further evaluation is necessary to show the effects of a conditioned wrapped muscle on LV systolic function and dimensions in the long-term.

Surgical restoration of the left ventricle for postinfarction aneurysm.

BACKGROUND: Surgical left ventricular reduction is under investigation as an alternative to, or a bridge for, heart transplantation in patients with a left ventricular aneurysm. In fact, acute myocardial infarction can result in the development of a dyskinetic or akinetic left ventricular aneurysm which may in turn cause congestive heart failure, ventricular arrhythmias, and the formation of mural thrombi. The aim of this study was to evaluate the current operative risk of surgical restoration of the left ventricle and the early and late clinical results. METHODS: From January 1997 to December 2001, 94 patients (84 males and 10 females) presenting with a postinfarction aneurysm were submitted to surgical restoration of the left ventricle. All patients presented with symptoms of heart failure and/or angina. The preoperative NYHA functional class was: I in 6 patients, II in 22 patients, and III in 66 patients. No patient was in NYHA class IV at the time of surgery. The preoperative ejection fraction was 30 +/- 7.9%. In 25 patients mural thrombi were identified and surgically removed. In patients with preoperative evidence of ventricular arrhythmias the Harken procedure was performed intraoperatively. The ventricular preoperative and postoperative performances were also studied in 10 patients using P-V loops obtained through a conductance catheter. RESULTS: The in-hospital mortality was 3.2%. The mean length of hospitalization was 7 +/- 2.9 days. At follow-up (mean 26 +/- 14.8 months) we observed an early improvement in the ejection fraction (30 +/- 7.9 vs 48 +/- 8.0%) and a decrease in the end-diastolic and end-systolic volumes and mean pulmonary pressure (139 +/- 37 vs 84 +/- 17 ml/m2, 105 +/- 39 vs 52 +/- 20 ml/m2, 35 +/- 8.4 vs 23 +/- 4.3 mmHg). CONCLUSIONS: These results suggest that ventricular restoration is indicated in all patients with a postinfarction dyskinetic or akinetic aneurysm. The operation, if performed appropriately, is associated with a low in-hospital mortality and morbidity. A postoperative improvement in the early and long-term cardiac functions was demonstrated. An improvement in symptoms and quality of life was documented, increasing our expectations of an increased long-term survival.

The effect of biventricular pacing on cardiac function after weaning from cardiopulmonary bypass in patients with reduced left ventricular function: a pressure-volume loop analysis.

OBJECTIVE: Patients with severely reduced left ventricular function undergoing coronary artery bypass grafting have increased complication rates. We hypothesized that temporary postoperative atrial synchronous biventricular pacing would improve left ventricular function after cardiopulmonary bypass. METHODS: A left ventricular pressure-volume catheter was placed in 21 patients undergoing coronary artery bypass grafting (ejection fraction 29% +/- 5%). Pressure-volume loops were obtained after weaning from cardiopulmonary bypass with atrial synchronous biventricular, left ventricular, and right ventricular outflow tract pacing and atrial-only stimulation at 90 beats/min. RESULTS: Steady-state systolic and preload-independent parameters were superior for atrial synchronous biventricular and left ventricular pacing and atrial-only pacing relative to atrial synchronous right ventricular outflow tract pacing (P < .05). Diastolic parameters, excepting maximum negative rate of left ventricular pressure change, were unaffected. No significant differences were observed between atrial synchronous biventricular and left ventricular pacing and atrial-only pacing. Systolic dyssynchrony was significantly lower for atrial synchronous biventricular pacing (21% +/- 5%), atrial synchronous left ventricular pacing (20% +/- 6%), and atrial-only pacing (20% +/- 6%) versus atrial synchronous right ventricular outflow tract pacing (25% +/- 7%, P < .05). Atrioventricular interval during atrial-only stimulation was positively correlated with difference in stroke work between atrial synchronous biventricular pacing and atrial-only pacing (r(2) = 0.78, P > .001). CONCLUSION: Postoperative atrial synchronous biventricular and left ventricular pacing and atrial-only stimulation significantly improve systolic function relative to atrial synchronous right ventricular outflow tract pacing. If atrioventricular conduction is prolonged, atrial synchronous biventricular pacing is preferable to atrial-only pacing.