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UHC physicians James Revenaugh and Brian Whisenant run the Advanced Percutaneous Mechanical Support program at LDSH in Salt Lake City.
Background: There are some clinical conditions that result in weakening of the heart muscle to the point where it is no longer able to do its job – to deliver blood to the vital organs of the body. Sometimes this occurs abruptly, for example, if a person sustains a very large heart attack. Other times it can occur more gradually. Sometimes this process is reversible. If the weakness is due to longstanding narrowing of the arteries that supply blood to heart muscle (coronary artery disease), it is often at least partially reversible if normal blood flow can be restored to the muscle. This is usually achieved through either a coronary artery bypass procedure or through placement of one or more stents.
Risks Associated With Stenting: Although the risks associated with stent placement to open up blocked arteries are generally low, serious complications can occur. Some factors are known to increase the risk of performing a stent procedure including decreased heart muscle function, placing stents in old bypass grafts, treating narrowings that involve large side branch vessels (fig 1), and placing stents in the left main coronary artery (fig 2).
If one or more of these factors exist, it is sometimes necessary to support the heart mechanically to lessen the risk of procedural failure, cardiac arrest, or heart attack. Mechanical circulatory support may be needed just during the procedure; sometimes it required for a longer period of time.
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Types of Available Percutaneous Mechanical Circulatory Support: Left Ventricular Assist Devices (LVAD) are semipermanently or permantly implanted pumps which require open heart surgery, but are very effective in supporting patients for months or even years. Devices placed through blood vessels in the legs (percutaneous devices) can support a patient for up to a few weeks. Currently there are two commercially available forms of percutaneous mechanical circulatory support – the intraaortic balloon pump (IABP) (fig 3) and percutaneous ventricular assist device (PVAD). The IABP, which is commonly used in hospitals throughout the country, involves the rapid inflation and deflation of a long balloon which sits in the main blood vessel in the body, the aorta. The inflation is timed to the heart beat and is used to augment the pumping function of the heart. It can be helpful in improving blood flow in the coronary arteries but cannot support heart function completely.
It is also a relatively small caliber device, unlikely to cause significant damage to the arteries through/in which it is placed.
The PVAD is a continuous flow pump that can fully support one’s heart function on a temporary basis. Its placement is technically more difficult as it involves placement of large bore tubes (cannulae) in the artery and vein in the leg, and involves puncturing the partition between two heart chambers, a trans-septal puncture (fig 5). There are currently roughly sixty medical centers in the country which use this device. LDSH was the third center in the country to use the device and was instrumental demonstrating its safety and effectiveness; UHC physicians performed these procedures (Dr. Revenaugh has performed all but one of the procedures done at LDSH). We have used the device to support patients through high risk procedures such as complex stent procedures and complex arrhythmia ablation. It has also served as a bridge to heart transplant, to more long term mechanical circulatory support devices, and to recovery.
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Our Program: All patients who are considered for high risk cardiac procedures requiring advanced circulatory support are evaluated by a team of physicians including a heart failure/heart transplant cardiologist, a cardiothoracic surgeon skilled in advanced mechanical support therapy, a critical care medicine specialist who has advanced training in mechanical circulatory support, and an interventional cardiologist with PVAD experience. Decision making for this complex subset of patients is team-based; multiple physicians are usually involved in the evaluation and care of the patient before and after the procedure. Since the program was initiated in 2001, refinements in the technique (developed by UHC physicians) have resulted in even better outcomes.
Our Outcomes: When the device has been used to treat patients in cardiogenic shock (a condition in which only about 20% of patients survive), roughly 80% of our patients have recovered and have been discharged from the hospital. When used to support patients through high risk angioplasty/stent procedures and arrhythmia ablation, over 90% have been successful, and the patients have been discharged home without significant long term complications, with most patients enjoying significant improvement in heart muscle function as a result of the procedure (these statistics reflect our experience through spring of 2006). The results of our experience were presented at an international circulatory support meeting in June of 2005 (JRRevenaugh, et. al., American Society of Artificial Internal Organs [ASAIO], 6/05).
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