Direct myocardial effects of OPC-18790 in human heart failure: beneficial effects on contractile and diastolic function demonstrated by intracoronary infusion with pressure-volume analysis

Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops

Introduction

The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models.

Methods and Results

A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax).

Conclusions

For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

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.

Quantification of left ventricular mechanical dyssynchrony by conductance catheter in heart failure patients

Mechanical dyssynchrony is an important codeterminant of cardiac dysfunction in heart failure. Treatment, either medical, surgical, or by pacing, may improve cardiac function partly by improving mechanical synchrony. Consequently, the quantification of ventricular mechanical (dys)synchrony may have important diagnostic and prognostic value and may help to determine optimal therapy. Therefore, we introduced new indexes to quantify temporal and spatial aspects of mechanical dyssynchrony derived from online segmental conductance catheter signals obtained during diagnostic cardiac catheterization. To test the feasibility and usefulness of our approach, we determined cardiac function and left ventricular mechanical dyssynchrony by the conductance catheter in heart failure patients with intraventricular conduction delay ( n = 12) and in patients with coronary artery disease ( n = 6) and relatively preserved left ventricular function. The heart failure patients showed depressed systolic and diastolic function. However, the most marked hemodynamic differences between the groups were found for mechanical dyssynchrony, indicating a high sensitivity and specificity of the new indexes. Comparison of conductance catheter-derived indexes with septal-to-lateral dyssynchrony derived by tissue-Doppler velocity imaging showed highly significant correlations. The proposed indexes provide additional, new, and quantitative information on temporal and spatial aspects of mechanical dyssynchrony. They may refine diagnosis of cardiac dysfunction and evaluation of interventions, and ultimately help to select optimal therapy.

Diastolic function in hypertension

Diastolic dysfunction in patients with hypertension may present as asymptomatic findings on noninvasive testing, or as fulminant pulmonary edema, despite normal left ventricular systolic function. Up to 40% of hypertensive patients presenting with clinical signs of congestive heart failure have normal systolic left ventricular function. In this article we review the pathophysiologic factors affecting diastolic function in individuals with diastolic function, current and emerging tools for measuring diastolic function, and current concepts regarding the treatment of patients with diastolic congestive heart failure.

Right ventricular support for off-pump coronary artery bypass grafting studied with bi-ventricular pressure--volume loops in sheep

OBJECTIVES

Tilting the heart during off-pump coronary artery bypass grafting (OPCABG) causes a strong decrease in cardiac output. It is hypothesized that this decrease is caused by reduced right ventricular filling and that right ventricular support is thus the best way to restore cardiac output. Simultaneous left and right ventricular pressure-volume loops were used to test this hypothesis.

METHODS

In seven sheep, the heart was tilted with the use of an Octopus device. After unsupported tilting, a novel right ventricular support, the Enabler, was activated at a pulsatile flow of 1.6 l/min. Pressure-volume loops of both ventricles were obtained using conductance catheters, and cardiac output was monitored with an aortic flow probe.

RESULTS

Tilting reduced cardiac output by 31% (4.4--3.1 l/min, P=0.001) and right ventricular end-diastolic volume by 44% (86--51 ml, P=0.005), while right ventricular end-diastolic pressure did not decrease. Left ventricular systolic pressure was not significantly reduced upon tilting and even increased in two animals. During Enabler right ventricular support, the cardiac output remained 23% lower than pre-tilting values (3.4 vs. 4.4 l/min, P=0.001).

CONCLUSIONS

Restricted right ventricular filling is the primary cause of the strong decrease in cardiac output during tilting. The Enabler right ventricular support can currently not restore cardiac output to pre-tilting values, mainly caused by its limited output and a decrease in right ventricular output upon Enabler activation. Constant monitoring of cardiac output is crucial during (unsupported or supported) tilting as blood pressure alone may not reflect the extent of the reduction in cardiac function.

Clinical overview of the novel inotropic agent toborinone

Toborinone (OPC-18790, Otsuka Pharmaceutical Co. Ltd, 2(1H) -quinolone,6-[3-[ [3,4-dimethoxyphenyl)methyl] amino]-2-hydroxy prop oxyl]-,(.+-.)-) is a novel iv. inotropic agent. Positive inotropic effects are produced by PDE inhibition with the resulting increase in cAMP and intracellular calcium levels. Unlike other inotropic agents that increase cAMP, there is an absence of positive chronotropic effects, which are attributed to prolongation of the action potential due to blockade of delayed rectifier currents. There is also marked venous and arterial vasodilating properties. The absence of heart rate increases results in decreased myocardial oxygen consumption compared with conventional inotropes. Studies in human heart failure patients have been consistent with previous work in animal studies, confirming the effects of toborinone as being positive inotropy (relatively weak), marked arterial and venous vasodilatation and absence of increase in myocardial oxygen consumption. Data regarding safety in larger clinical trials, particularly regarding arrhythmias, is at present unavailable. This information will determine whether this agent becomes an accepted iv. therapeutic option for congestive heart failure.

Ambulatory blood pressure monitoring and echocardiography--noninvasive techniques for evaluation of the hypertensive patient

Clinic blood pressure measurements have only limited ability to determine which hypertensive patients are at greatest risk of cardiovascular events. Ambulatory blood pressure monitoring allows for noninvasive measurement of blood pressure throughout the 24-hour period. This may help to clarify discrepancies between blood pressure values obtained in and out of the clinic and confirm the presence of white-coat hypertension, broadly defined as an elevated clinic blood pressure but a normal ambulatory blood pressure. Ambulatory blood pressure values have been shown to have a better relationship to cardiovascular morbidity and mortality and end-organ damage than clinic blood pressure values. Further, patients with white-coat hypertension appear to be at greater risk of cardiovascular morbidity and end-organ damage than a normotensive population, although they are at less overall risk than a hypertensive population. Hypertensive heart disease is characterized by diastolic dysfunction, increased left ventricular mass, and coronary flow abnormalities. Left ventricular hypertrophy increases the risk of coronary heart disease, congestive heart failure, stroke, ventricular arrhythmias, and sudden death. A variety of invasive and noninvasive techniques are described herein that measure left ventricular mass, diastolic function, and coronary blood flow abnormalities. Most antihypertensive treatments promote regression of left ventricular hypertrophy and reversal of diastolic dysfunction, which may decrease symptoms of congestive heart failure and improve survival.