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At least 163 records · Page 9Linked to original sources
PubMed1998

Experimental development of an electrically stimulated biological skeletal muscle ventricle for chronic aortic counterpulsation.

OBJECTIVE: The chronic shortage of donor organs for cardiac transplantation and the high costs for mechanical assist devices demand the development of alternative cardiac assist devices for the treatment of severe heart failure. Cardiac assistance by stimulated skeletal muscles is currently investigated as such a possible alternative. The goal of the presented study was to construct a newly designed biological skeletal muscle ventricle and to evaluate its possible hemodynamic efficacy in an acute sheep model. METHODS: A total of 14 adult sheep were used for acute experiments. The entire thoracic aorta including the aortic root was excised from a donor sheep. An aorto-pericardial pouch conduit (APPC) was created by enlarging the aortic circumference in its middle section with two strips of pericardium. This biological conduit was anastomosed in parallel to the descending aorta of a recipient sheep, using the aortic root as an inflow valve to the conduit. Stimulation electrodes were applicated to the thoracodorsal nerve and the latissimus dorsi muscle was detached from the trunk and wrapped around the pouch. ECG-triggered functional electrical stimulation was applied during cardiac diastole to simulate aortic counterpulsation. Stimulation was performed during various hemodynamic conditions. RESULTS: A standardised surgical procedure suitable for long term studies was established during six experiments. An APPC, with 70-80 mm filling volume, was found to be of optimal size. In another eight experiments, hemodynamic measurements were performed. Under stable hemodynamic conditions the stimulation of the biological skeletal muscle ventricle induced a significant increase of mean arterial pressure by 14% and mean diastolic pressure by 26%. During pharmacologically induced periods of cardiac failure, the stimulation of the APPC increased mean arterial pressure by 13% and mean diastolic pressure by 19%. In all eight experiments, the diastolic peak pressure reached supra-systolic values during stimulation. CONCLUSIONS: The results demonstrate the hemodynamic efficacy of this newly designed biological skeletal muscle ventricle as an aortic counterpulsation device. Chronic experiments using a preconditioned fatigue-resistant muscle will further help to evaluate its possible clinical significance.

Animals↗
PubMed1994

Concepts of intraaortic balloon counterpulsation.

The concept of intraaortic balloon counterpulsation (IABC) was developed in the late 1960s, primarily for use in cardiogenic shock. Since that time, many published reports have documented the efficacy of this mechanical assist device in an expanding number of clinical situations. Research has shown that intraaortic balloon counterpulsation increases coronary flow velocity and decreases afterload, thus favorably affecting myocardial oxygen supply and demand. This article offers a review of the concepts and mechanics of IABC, as well as current indications and contraindications for use. The nurse must be able to recognize and address potential complications to ensure positive patient outcomes.

Contraindications↗
PubMed2004

Accelerated reperfusion of poorly perfused retinal areas in central retinal artery occlusion and branch retinal artery occlusion after a short treatment with enhanced external counterpulsation.

BACKGROUND: To date, no satisfactory therapy has become available for patients with acute central retinal artery occlusion (CRAO) or branch retinal artery occlusion (BRAO). Enhanced external counterpulsation (EECP) is a new noninvasive procedure that increases perfusion of inner organs. In the current study, the authors measured the impact of EECP on reperfusion in ischemic retinal tissue. METHODS: In a prospective, randomized study, 20 patients with CRAO or BRAO were included. Ten patients were given hemodilution therapy and 2 hours of EECP, and 10 patients were given regular hemodilution therapy only. Quantification of changes in retinal perfusion was carried out by means of scanning laser Doppler flowmetry (in arbitrary units). RESULTS: Enhanced external counterpulsation caused no observable adverse events. A significant increase in perfusion occurred immediately after EECP in the ischemic retinal areas (57 +/- 19 arbitrary units versus 99 +/- 14 arbitrary units). In contrast, no change was measured in the group not treated with EECP (83 +/- 19 arbitrary units versus 89 +/- 44 arbitrary units). Forty-eight hours later, a significant increase in perfusion could be shown in the ischemic retina of both groups, and no significant difference of perfusion was found between the two groups any longer. CONCLUSION: The current study suggests that EECP could be a clinically useful and safe procedure in patients with CRAO or BRAO to accelerate recovery of perfusion in ischemic retinal areas.

Aged↗
PubMedDate not supplied

A new treatment modality in heart failure enhanced external counterpulsation (EECP).

Heart failure remains a significant health problem in the United States and in the world. Despite a surfeit of recent diagnostic and therapeutic advances, patients with heart failure remain inadequately helped. The overwhelming need for new and better therapies continues to stimulate scientists to investigate new technologies. Over the past several years the use of enhanced external counterpulsation as a treatment for chronic angina has steadily increased. Recently, its potential role in heart failure management has been shown. We review the role of enhanced external counterpulsation in heart failure management as an emerging noninvasive outpatient therapy.

Angina Pectoris↗
PubMedDate not supplied

Development and early testing of a simple subcutaneous counterpulsation device.

The intra-aortic balloon pump has been widely and successfully used as a treatment for cardiac dysfunction, but it only has short-term applications. To overcome this limitation, a superficial counterpulsation device (CPD) is being developed to provide extended counterpulsation support to promote myocardial recovery. The CPD is a valveless, monoport, pneumatically driven, 40-ml sac that is intended to be implanted in a pacemaker-type pocket in the subclavian fossa. The sac is designed to fill in systole and empty during diastole through an outflow graft anastomosed to the subclavian artery. A feasibility study was conducted to investigate acute hemodynamic responses to the CPD in eight calves with diminished cardiac function. The CPD augmented aortic diastolic pressure, reduced left ventricular peak systolic and aortic ejection pressures by up to 18%, and increased diastolic coronary flow by up to 21% and stroke volume by up to 12%. A cadaver fit study demonstrated that the human subclavian artery is a reasonable anastomosis site to consider and that the 40-ml CPD needs to be reduced in size to provide a better anatomical fit. The clinical attractiveness of this approach is that it may provide extended support through a subcutaneous surgical procedure.

Animals↗
PubMed1994

Muscle- and pneumatic-powered counterpulsating LVADs: a pilot study.

There is a worldwide interest in supporting the failing heart with a skeletal muscle by either wrapping it around the natural heart (dynamic cardiomyoplasty) or by constructing a skeletal muscle ventricle (SMV) used for counterpulsation. Conventional cardiomyoplasty in many clinics carries an operative mortality rate of 15-20% partly because it requires 6 weeks to train the muscle to contract continually. A flexible, pear-shaped blood pump with an inflatable air chamber was designed and made around which a muscle can be wrapped. The advantage of our design is that it can also be driven by pneumatic power, immediately supporting the circulation of a seriously ill patient while that patient is still on the operating table. After a period of time to allow for revascularization and the subsequent training of the muscle, the external pneumatic power can be gradually discontinued. Then the assisted patient becomes tether-free. If, at any time, the muscle power fails, the pneumatic-powered mechanism can be reactivated. In the preferred approach, the blood pump is connected to the aorta for diastolic counterpulsation. A muscle can either be wrapped around the blood pump directly, or around one of two separate muscle pouches connected to the blood pump. To facilitate surgery, a large pouch is inserted under the musculus latissimus dorsi, which is connected to a blood pump. When stimulated, the muscle will contract over the pouch compressing it and providing power to the blood pump. If it is found that the pressure generated in the pouch cannot meet the aortic blood pressure, it can be augmented by using a pressure amplifier.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Enhanced external counterpulsation improves exercise duration and peak oxygen consumption in older patients with heart failure: a subgroup analysis of the PEECH trial.

The Prospective Evaluation of Enhanced External Counterpulsation in Congestive Heart Failure (PEECH) trial demonstrated that enhanced external counterpulsation (EECP) therapy increased exercise duration and improved functional status and quality of life without affecting peak oxygen consumption. The authors present data from a prespecified subgroup of elderly patients (65 years or older) enrolled in the PEECH trial. The 2 co-primary end points were the percentage of subjects with a >60-second increase in exercise duration and the percentage of subjects with a >1.25-mL/kg/min increase in peak volume of oxygen consumption. At 6-month follow-up, the exercise responder rate was significantly higher in EECP patients compared with controls (P=.008). Further, in contrast to the overall PEECH study, the EECP group demonstrated a significantly higher responder rate for peak oxygen consumption (P=.017). The authors conclude that an older subgroup of PEECH subjects confirms the beneficial effect of EECP in patients with chronic, stable, mild-to-moderate heart failure.

Aged↗
PubMed1990

Skeletal muscle ventricles in circulation as aortic diastolic counterpulsators: twelve-month update.

In previous studies, we have shown that canine skeletal muscle ventricles (SMVs) of various designs could develop stroke work intermediate between that of the canine left and right ventricle. We have subsequently reported that SMVs could be used as aortic diastolic counterpulsators. In some animals the SMVs pumped blood effectively for several weeks. Thromboembolism, however, caused renal failure, which was responsible for the demise of the longest surviving animals. More recently, we have studied a group of 15 dogs that had skeletal muscle ventricles constructed from their latissimus dorsi muscle and lined with autogenously derived tissues, either pleura, pericardium or fibrous tissue induced by a Teflon mandrel. We now report on one of those animals, that has survived more than 1 year. She remains active and in apparent good health with no clinical evidence of thromboemboli. Her SMV continues to generate effective aortic diastolic counterpulsation.

Animals↗
PubMed2001

Numerical simulation of enhanced external counterpulsation.

Enhanced external counterpulsation (EECP) is a noninvasive, counterpulsative method to provide temporary aid to the failing heart by sequentially inflating cuffs on the lower extremity out-of-phase with the left ventricle. Optimization of the method necessitates consideration of the hemodynamics created by EECP and the mode of action providing patient benefit. A computational model based on the governing one-dimensional equations is developed that simulates cardiovascular hemodynamics during EECP. The model includes a 30-element arterial system including the left ventricle, bifurcations, and peripheral arterial vessels. Effects of vessel collapse as external pressure is applied, arterial refilling on pressure release, changes in aortic pressure, and shear stress generated in the arteries are each investigated. Device parameters are systematically varied to determine their effect on system performance. Results show the potential for significant collapse and shear augmentation throughout the arteries of the lower extremity. Performance is strongly influenced by the mean level of external pressurization and the timing of cuff inflation, but less so by the relative timing and pressure differences between cuff segments.

Biomedical Engineering↗
PubMed1998

Performance analysis of a cardiac assist device in counterpulsation.

Performance of a cardiac assist device pumping chamber in counterpulsation was evaluated using numerical simulations of the unsteady, three-dimensional flow inside the chamber and an analytical model of the force required to eject and fill the chamber. The wall shear stress within the device was similarly computed and modeled. The analytical model was scaled to match the numerical results and then used to predict performance at physiological operating conditions. According to these models for a stroke volume of 70 ml, between 0.4 and 1.0 W is required for counterpulsation at a frequency of 1.33 Hz against a restorative spring, depending on the spring constant chosen. The power and the maximum force calculated are within the ranges a trained skeletal muscle is capable of providing. Shear stress predictions show that platelet activation in the absence of surface effects and hemolysis due to high shear are unlikely to occur with this design. Furthermore, vortices that develop in the chamber during filling are predicted to increase blood mixing and provide favorable washing of the chamber walls. A computational-analytical approach such as this may have potential to aid rapid performance evaluation of new devices and streamline the design optimization process.

Counterpulsation↗
PubMed2006

Counterpulsation from the skeletal muscle ventricle and the intraaortic balloon pump in the normal and failing circulations.

BACKGROUND: The intra-aortic balloon pump (IABP) is the device that is in most common use to provide cardiovascular support. A skeletal muscle ventricle (SMV) was configured to produce counterpulsation in the thoracic aorta similar to that obtained with an IABP. The hemodynamic effects of an IABP and a SMV in the same animal and in both normal and failing circulations were assessed. METHODS AND RESULTS: SMVs were connected to and IABPs were placed in the thoracic aorta of 12 anesthetized pigs. Hemodynamic parameters during the IABP- or the SMV-assisted beat were compared with those during the preassist beat. Acute heart failure was induced in 6 of the pigs by snaring the left anterior descending coronary artery (LAD). The hemodynamic effects of the IABP and the SMV were then reassessed. In the assisted cycles, SMV activation increased the mean aortic diastolic pressure (MADP) by 26.5+/-3.5%, the mean diastolic LAD flow by 48.4+/-7.2%, and endocardial viability ratio (EVR) by 31.6+/-3.8% (P<0.0001). In the same animals, IABP assist increased MADP by 19.8+/-2.3%, mean diastolic LAD flow by 37.2+/-3.9%, and EVR by 21.4+/-3.0% (P<0.0001). Under acute heart failure conditions, both SMV and IABP assist significantly increased MADP, mean diastolic LAD flow, and EVR. CONCLUSIONS: In both the normal and failing circulations, the SMV was an effective counterpulsator, providing cardiac assist that was at least equal to that available from an IABP. The SMV may therefore provide the proven benefits of an IABP in ambulant patients.

Animals↗
PubMed1999

Chronic pulmonary artery balloon counterpulsation in sheep via percutaneous route.

BACKGROUND: In clinical practice pulmonary artery balloon counterpulsation (PABC) has been utilized only in the operative setting with the balloon housed in a graft attached to the pulmonary artery. Clearly, percutaneous insertion of a dedicated pulmonary artery balloon is a desirable goal for patients requiring temporary assist for right ventricular failure. METHODS: To address the question of right sided cardiopulmonary tolerance for a chronic indwelling pulmonary artery balloon, six adult ewes underwent percutaneous placement of an 11 ml pulmonary artery balloon, via the femoral vein. Effective pumping and timing were monitored for 48 hours at which time the animals were sacrificed. At autopsy gross and microscopic study of all right heart structures, the pulmonary arteries and the lungs were studied for adverse effects. RESULTS: There were inconsequential minor abrasions to right heart structures in most animals. The pulmonary artery in five of six animals revealed ecchymoses and some transmural hemorrhage, but no necrosis or perforation. There was no pulmonary injury that could not be ascribed to postoperative atelectasis. CONCLUSIONS: This study demonstrates that chronic pulmonary artery balloon counterpulsation can be carried out for a period of 48 hours without significant injury to right heart and pulmonary structures in the ovine model

Adult↗
PubMed2002

[Effects of external counterpulsation on the pulsatility of blood pressure in human subjects].

Pulsatile blood flow plays an important role in maintaining normal vascular endothelial function. Quantitative measurement of pulsatility of human arterial blood pressure and the influence of enhanced external counterpulsation (EECP) on the pulsatility were investigated in this study. Eight healthy young male volunteers aged 22 to 35 were included. A 4F tip transducer catheter was inserted under local anaesthesia into the radial artery up to the aortic arch. Intraarterial blood pressure was recorded before and during EECP. Blood pulse pressure, pulsatility index (ratio of peak pressure to end diastolic pressure) and standard deviation of blood pressure in 5 cardiac cycle was calculated to evaluate the pulsatility of arterial blood pressure. The results showed that blood pulse pressure, pulsatility index and standard deviation of blood pressure were elevated from 47 +/- 5 mmHg, 1.64 +/- 0.11 and 13.6 +/- 1.5 mmHg to 77 +/- 3 mmHg, 2.46 +/- 0.25 and 19.3 +/- 2.2 mmHg before and during EECP respectively (P < 0.05). Decreasing of systolic pressure and increasing of diastolic pressure during counterpulsation were also observed. EECP gives an elevation of pulsatility to human blood pressure.

Adult↗
PubMed2005

Non-invasive diagnosis of acute ischemic bowel disease detected as hepatic portal venous gas during intra-aortic balloon percutaneous counterpulsation.

The authors report a very unusual case of non-invasive diagnosis of acute ischemic bowel disease detected as hepatic portal venous gas during intra-aortic balloon percutaneous counterpulsation. A 64-year-old man with acute ST-elevation myocardial infarction complicated by cardiogenic shock was treated with percutaneous angioplasty and intra-aortic balloon percutaneous counterpulsation. The post-procedural period was complicated by severe abdominal pain. Abdominal computed tomography revealed hepatic portal venous gas. Multiple kidney and splenic ischemic areas were also identified. Colonoscopy showed signs referring to acute ischemic colitis. Computed tomography detection of hepatic portal venous gas has permitted the non-invasive diagnosis of bowel necrosis.

Acute Disease↗
PubMed2006

The benefits and safety of external counterpulsation in symptomatic heart failure.

BACKGROUND: External counterpulsation is a safe and effective method of alleviating angina pectoris, but the mechanism of benefit is not understood. OBJECTIVES: To evaluate the safety and efficacy of external counterpulsation therapy in heart failure patients. METHODS: Fifteen symptomatic heart failure patients (subsequent to optimal medical and device therapy) underwent 35 hourly sessions of ECPT over a 7 week period. Before and after each ECPT session we performed pro-B-type natriuretic peptide and brachial artery function studies, administered a quality of life questionnaire, and assessed exercise tolerance and functional class. RESULTS: Baseline left ventricular ejection fraction was 28.1+/-5.8%. ECPT was safe and well tolerated and resulted in a reduction in pro-BNP levels (from 2,245+/- 2,149 pcg/ml to 1,558+/-1206 pcg/ml, P= 0.022). Exercise duration (Naughton protocol) improved (from 720+/-389 to 893+/-436 seconds, P= 0.0001), along with functional class (2.63+/-0.6 vs. 1.93+/-0.7, P= 0.023) and quality of life scores (54+/-22 vs. 67+/-23, P= 0.001). Nitroglycerine-mediated brachial vasodilatation increased (11.5+/-7.3% vs. 15.6+/-5.2%, P=0.049), as did brachial flow-mediated dilation (8.35+/-6.0% vs. 11.37+/-4.9%, P= 0.09). CONCLUSIONS: ECPT is safe for symptomatic heart failure patients and is associated with functional and neurohormonal improvement. Larger long-term randomized studies with a control arm are needed to confirm these initial encouraging observations.

Adult↗
PubMed1991

[Assessment of the systematic preoperative insertion of an intra-aortic counterpulsation balloon in patients at high operative risk for coronary artery surgery].

The authors report their experience with pre-operative percutaneous balloon counterpulsation in 75 patients considered to be at high operative risk for coronary artery surgery, mainly because of unstable angina refractory to maximum medical therapy. The criteria to define high surgical risk are reported. The results and the vascular risk in relation to this technique are estimated. Two patients died during the operation, 12 died during the early postoperative phase without any improvement following intra-aortic balloon pumping. The rate and severity of complications of percutaneous insertion of intra-aortic balloon counterpulsation are low and seem to be related to pre-existing arteriosclerosis. The stabilizing effect of this pre-operative insertion on angina, refractory to medical treatment, seems to be justifiable in patients presenting one of the defined criteria.

Adult↗
PubMed1989

Feasibility of pulmonary artery balloon counterpulsation via the percutaneous route: pathological studies on the heart and lungs.

The efficacy of pulmonary artery balloon counterpulsation (PABC) has been previously demonstrated. Clinically this is usually achieved by suturing a Dacron graft to the side of the pulmonary artery with an intra-aortic balloon pulsating inside the graft. PABC via the percutaneous route has not been previously reported, although it has been demonstrated experimentally that an intrapulmonary artery balloon inserted via the outflow of the right ventricle provides effective counterpulsation. The morphologic effects of PABC on the heart and lungs have not been previously demonstrated. This study evaluates the feasibility of PABC via the percutaneous route and assesses the morphologic changes of PABC on the heart and lungs of pigs. Results indicate that PABC via the percutaneous route is technically feasible. However, after 24 h of PABC morphologic changes occurred in the heart and lungs, consisting of valvular and mural thrombi and hemorrhage. Histopathologic evaluation of the lungs revealed interstitial and intra-alveolar hemorrhage and pulmonary emboli. The etiology of these pathologic changes are likely multifactorial. Further studies are necessary to fully delineate the short and long term effects of PABC prior to initiation of clinical trials with this new percutaneous assist device.

Animals↗