Diastolic heart failure evaluation

Patients with diastolic heart failure are typically dependent upon preload to maintain adequate cardiac output. While patients with symptomatic volume overload will benefit from careful modulation of intravascular volume, volume reduction should be accomplished gradually and treatment goals reassessed frequently. In addition to cautious volume management, it is important to maintain synchronous atrial contraction in such patients, which maintains adequate left ventricular filling during the latter phase of diastole. Cardiac function is often severely impaired if patients with diastolic heart failure develop atrial fibrillation, particularly in the context of sub-optimal ventricular rate control. Meticulous control of the ventricular rate with drugs that slow AV conduction is mandatory (see Chapter 34) and restoration of sinus rhythm should be considered. It is also important to evaluate and treat conditions that are associated with dynamic abnormalities of diastolic function, such as myocardial ischemia and poorly controlled systemic hypertension. 

Unlike systolic HF, few prospective trials have evaluated the safety and efficacy of various cardiac medications in patients with diastolic HF or preserved ejection fraction. The Candesartan in Heart Failure Assessment of Reduction in Mortality and Morbidity (CHARM) study demonstrated that angiotensin receptor blockade with candesartan resulted in beneficial effects on HF morbidity in patients with preserved LVEF similar to those seen in depressed LV function.25... 

Because of the ease of introducing intravenous and intra-arterial catheters and measuring blood flow and blood pressure, dogs are commonly used to conduct hemodynamic studies. These studies evaluate the effect of the test compound on systolic and diastolic blood pressure, heart rate, cardiac output, dp/dt, respiration, ECG, and ventricular pressure. From these data, effects desirable for treating angina pectoris, congestive heart failure, coronary vasospasm, and myocardial infarction can be detected. 

The Multicenter InSync ICD Randomized Clinical Evaluation II (MIRACLE ICD II) was a follow-up randomized, double-blind, parallel-conlrolled clinical trial of CRT in New York Heart Association Functional Class II heart failure patients on optimal medical therapy with a left ventricular ejection fraction < 0.35, a QRS > 130ms and a Class I indication for an ICD. Patients were randomized to control group (ICD activated, CRT off) and to CRT group (ICD activated, cardiac-resynchronization therapy on). No significant differences were noted in 6-min walk distance or quality of life scores or peak V02. There were significant improvements in left ventricular diastolic and systolic volumes and in left ventricular ejection fraction (198). 

Thoracic fluid is associated with decreased impedance between a ventricular lead and the pacing system generator. Two preliminary clinical studies have reported varying results on the clinical utility of thoracic impedance monitoring for predicting hemodynamic status. The Medtronic Impedance Diagnostics in Heart Failure Trial (MlD-HeFT) evaluated 33 patients with Class III or IV heart failure due to systolic dysfunction (n = 25) or diastolic dysfunction (n =... 

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