Hemodynamics and myocardial blood flow patterns after placement of a cardiac passive restraint device in a model of dilated cardiomyopathy

Abstract

Background The present study examined a cardiac passive restraint device which applies epicardial pressure (HeartNetTM Implant) in a clinically relevant model of dilated cardiomyopathy (DCM) to determine effects on hemodynamic and myocardial blood flow patterns. Methods DCM was established in 10 pigs (3 weeks atrial pacing, 240 beats per minute). Hemodynamic parameters and regional left ventricle (LV) blood flow were measured under baseline conditions and following acute HeartNet (Paracor Medical Inc, Sunnyvale, CA) placement. Measurements were repeated following adenosine infusion, allowing maximal coronary vasodilation and coronary flow reserve determination. Results LV dilation and systolic dysfunction occurred relative to baseline as measured by echocardiography. LV end diastolic dimension increased and LV fractional shortening decreased (3.8±0.1 vs 6.1±0.2cm and 31.6±0.5 vs 16.2±2.1%, both p<0.05 respectively) consistent with the DCM phenotype. The HeartNet was successfully deployed without arrhythmias and a computed median mid-LV epicardial pressure of 1.4 mmHg was applied by the HeartNet throughout the cardiac cycle. Acute HeartNet placement did not adversely affect steady state hemodynamics. With the HeartNet in place, coronary reserve was significantly blunted. Conclusions In a large animal model of DCM, the cardiac passive restraint device did not appear to adversely affect basal resting myocardial blood flow. However, following acute HeartNet placement, LV maximal coronary reserve was blunted. These unique results suggest that cardiac passive restraint devices which apply epicardial transmural pressure can alter myocardial blood flow patterns in a DCM model. Whether this blunting of coronary reserve holds clinical relevance with chronic passive restraint device placement remains unestablished.

Optimized ventricular restraint therapy: Adjustable restraint is superior to standard restraint in an ovine model of ischemic cardiomyopathy

“…Large animal studies have shown that application of a meshlike restraint device at levels of up to 2.5 mm Hg can be safely applied without significant detrimental effects on coronary blood flow. 15 This corresponds with our current and previous findings of beneficial changes with restraint up to 3 mm Hg without adverse hemodynamic effects.…”

Direct Epicardial Assist Device using Artificial Rubber Muscle in a Swine Model of Pediatric Dilated Cardiomyopathy

“…Six young pigs underwent DCM induction by a relatively low right ventricular pacing rate of 170 bpm for 6 to 8 weeks, which resulted in the development of increased EDV size and low EF and CO, indicating successful establishment of DCM models. Previous studies showed the development of tachycardia-induced heart failure in response to 220 to 240 bpm for 1 to 3 weeks in pigs weighing 25 to 45 kg [21][22][23][24]. We implanted pacemakers in 6 pigs (weight, 10-12 kg) in order to get smaller DCM models that approximate young children.…”

Models of Pacing‐Induced Heart Failure

“…This work was supported by the National Institute of Health grants HL057952 and HL095608 and a is a reduction in LV remodeling [80][81][82][83][84]. These devices can be placed at the time pacing DCM has become manifest, or at earlier time points during the development of this process [80][81][82][83][84].…”

“…These devices can be placed at the time pacing DCM has become manifest, or at earlier time points during the development of this process [80][81][82][83][84]. However, it should be pointed out that with the development of pacing-induced DCM and progression to CHF, significant hemodynamic instability and an arrhythmogenic substrate can be encountered.…”

“…However, it should be pointed out that with the development of pacing-induced DCM and progression to CHF, significant hemodynamic instability and an arrhythmogenic substrate can be encountered. Nevertheless, due to the significant uniformity of the LV remodeling process and the clear recapitulation of the DCM phenotype, the pacing model can be utilized to examine the acute effects of myocardial restraint devices [80,83]. Furthermore, as described in an earlier section, pacing-induced DCM is associated with significant MR, and therefore the use of these passive restraint devices to evaluate the effects on this response variable is possible [8,83,84].…”