These are both severe forms of diastolic dysfunction, and patients tend to have advanced heart failure symptoms:
Class III diastolic dysfunction patients will demonstrate reversal of their diastolic abnormalities on echocardiogram when they perform the Valsalva maneuver. This is referred to as "reversible restrictive diastolic dysfunction". Class IV diastolic dysfunction patients will not demonstrate reversibility of their echocardiogram abnormalities, and are therefore said to have "fixed restrictive diastolic dysfunction".The presence of either class III and IV diastolic dysfunction is associated with a significantly worse prognosis. These patients will have left atrial enlargement, and many will have a reduced left ventricular ejection fraction that indicates a combination of systolic and diastolic dysfunction.Imaged volumetric definition of systolic heart performance is commonly accepted as ejection fraction. Volumetric definition of the heart in systole was first described by Adolph Fick as cardiac output. Fick may be readily and inexpensively inverted to cardiac output and ejection fraction to mathematically describe diastole. Decline of ejection fraction paired with decline of E/A ratio seems a stronger argument in support of a mathematical definition of diastolic heart failure.Another parameter to assess diastolic function is the E/E ratio, which is the ratio of mitral peak velocity of early filling (E) to early diastolic mitral annular velocity (E). Diastolic dysfunction is assumed when the E/E ratio exceed 15.Newer echocardiographic techniques such as speckle tracking for strain measurement, particularly for the left atrium, are becoming increasingly utilised for the diagnosis of HFpEF. Treatment
Despite increasing incidence of HFpEF effective inroads to therapeutics have been largely unsuccessful.
Spinal fluid examination is not usually helpful. Treatment
Multifocal motor neuropathy is normally treated by receiving intravenous immunoglobulin (IVIG), which can in many cases be highly effective, or immunosuppressive therapy with cyclophosphamide or rituximab. Steroid treatment (prednisone) and plasmapheresis are no longer considered to be useful treatments(not usually some pt highly recommended); prednisone can exacerbate symptoms. IVIg is the primary treatment, with about 80% of patients responding, usually requiring regular infusions at intervals of 1 week to several months. Other treatments are considered in case of lack of response to IVIg, or sometimes because of the high cost of immunoglobulin. Subcutaneous immunoglobulin is under study as a less invasive, more-convenient alternative to IV delivery. References
External links

Overview of MMN at National Institute of Neurological Disorders and Stroke