Left Ventricular Torsional Hysteresis: A Global Parameter for Diastolic Function

Study Overview
=================
Brief Summary
-----------------
Diastolic dysfunction refers to abnormal mechanical properties of the myocardium and includes abnormal LV diastolic distensibility, impaired filling and slow or delayed relaxation- regardless of whether the ejection fraction is normal or depressed and whether the patient is asymptomatic or symptomatic. Epidemiologic studies have demonstrated high prevalence of diastolic heart failure (DHF). The quality of life of these patients is impaired and the clinical outcomes are similar to those with heart failure with systolic dysfunction. Therefore diastolic dysfunction has significant adverse economic impact that is expected to grow further with time. Clinical characteristics alone may not be sufficient to diagnose diastolic dysfunction. A number of invasive and non-invasive parameters have been proposed to diagnose diastolic dysfunction. Most of the presently used non-invasive parameters have a number of limitations. High fidelity measurement of the left ventricular pressures is needed to accurately diagnose diastolic dysfunction. Obtaining it in routine clinical practice is impractical. In this protocol the investigators have proposed a novel non-invasive parameter called 'Torsional Hysteresis' as a measure of diastolic function. This will be measured using non-invasive cardiac MRI technique. During left ventricular contraction and relaxation, myocardium deforms. During cardiac cycle the myocardium goes back to baseline state prior to beginning of each contraction. However the rate with which it returns to the baseline state is variable. Torsion indicates relative wringing motion of the ventricle around a left ventricular axis and is a global parameter of left ventricular deformation. The parameters have defined a new parameter called torsional hysteresis based on non invasive cardiac MRI assessment. The parameters have hypothesized that for diastolic dysfunction, the torsional hysteresis area is increased as compared to no diastolic dysfunction group.

Official Title
-----------------
Left Ventricular Torsional Hysteresis: A Global Parameter for Diastolic Function

Conditions
-----------------
Heart Failure, Diastolic Heart Failure, Heart Failure With Normal Ejection Fraction

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Major inclusion criteria: Normal screening LV ejection fraction. Exclusion Criteria: Atrial fibrillation or other significant cardiac arrhythmia on ECG Presence of pacemaker or defibrillator Angioplasty or primary coronary intervention PCI/PTCA during index cardiac catheterization. Patient is unable to undergo cardiac MRI due to contraindication to MRI (MRI incompatible metal prosthesis or implants or significant claustrophobia). Patient taking phosphodiesterase 5 inhibitor (eg. sildenafil) will be excluded due to potential interaction with nitroglycerin.

Ages Eligible for Study
-----------------
Minimum Age: 19 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Diastolic Function<br>Patients scheduled for cardiac catheterization. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To show that torsional hysteresis relates to invasive hemodynamic measure of diastolic function | To show that torsional hysteresis relates to invasive hemodynamic measure of diastolic function: a) Exponential fall of pressure during isovolumic relaxation phase by the time constant of relaxation, tau and b) LV end diastolic pressure-volume relationship (EDPVR). | one time at enrollment | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To demonstrate that torsional hysteresis is a relatively load independent measure of global diastolic function | To demonstrate that torsional hysteresis is a relatively load independent measure of global diastolic function by evaluating effects of nitroglycerin (NTG) on torsional hysteresis and correlating it to invasive hemodynamic measure of diastolic function including a) tau and b) EDPVR. | one time at enrollment | 
| To evaluate the sensitivity and specificity of torsional hysteresis in diagnosing diastolic dysfunction | To evaluate the sensitivity and specificity of torsional hysteresis in diagnosing diastolic dysfunction (as defined by invasive hemodynamic parameters: tau, EDPVR) and compare it to echocardiographic tissue Doppler assessment in patients undergoing cardiac catheterization for suspected diastolic dysfunction | one time at enrollment | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Heart Failure, Diastolic Heart Failure, Heart Failure with Normal Ejection Fraction