Innovative technologies and refinements of existing therapies are shaping 21st century cardiovascular diagnosis and treatment. Researchers are gaining new perspectives on diseases and their treatment at the cellular and subcellular levels. Cardiologists are evaluating and treating coronary arteries by means of intravascular intervention. Surgeons are shortening recovery times and increasing cost-effectiveness by using minimally invasive techniques. Moreover, innovators are combining treatments in new ways and offering hybrid procedures that confer numerous patient benefits. A few of the most recent developments in the cardiovascular field are reviewed below.
Though still in their early stages, several emerging therapies offer exceptional promise for revolutionizing the practice of cardiovascular medicine. For example, stem cell and genetic techniques are beginning to allow treatment at the cellular and subcellular levels. In addition, non-invasive yet highly sensitive imaging techniques are emerging as alternatives to traditional diagnostic imaging. Cardiovascular care will continue to build on these advances for many years to come.
Stem Cell Treatment
In this technique, stem cells are injected into the heart with the expectation that they will evolve into cardiac cells and replace the damaged cells. This approach has enormous potential to help the heart heal itself, particularly when other treatment options are unavailable. Stem cell therapy continues to expand as short-term follow-up studies reveal blood vessel development, cellular regeneration, and improved perfusion in treated areas. Currently, clinical investigators are focusing on four conditions: acute myocardial infarction (MI), myocardial ischemia without revascularization, ischemic cardiomyopathy, and peripheral vascular disease. Researchers are considering the relative efficacies of different cell types and delivery methods for treating these conditions.
Owing to ongoing controversy about the use of embryonic stem cells, alternative sources are being sought, including autologous cells from fat, bone marrow, skeletal muscle, or the heart itself. Animal models have recently shown that treatment is more effective if it relies on adult stem cells that express high levels of the aldehyde dehydrogenase enzyme.1 Stem cell delivery methods include transendocardial injection into viable heart muscle or into the periphery of damaged myocardium, as well as catheter-based injection.
In the developed world, coronary artery disease (CAD) is the leading cause of death and disability. The well-known risk factors for MI— increased age, tobacco use, obesity, lack of exercise, and hypertension—do not account for all cases of MI or CAD. In particular, patients who have a premature MI often lack traditional risk factors. Researchers now know that genetic risk factors underlie many MIs. Genes affect high-density lipoprotein levels, programmed cell death, blood clotting, and in-stent restenosis.
Since 2001, the Texas Medical Center Genetics (TexGen) project2 has been collecting genetic, clinical, and demographic data on the approximately 50,000 patients whom the participating institutions treat for cancer, cardiovascular disease, and stroke each year. By elucidating genetic risk factors, this information will help identify patients at increased risk for MIs, especially premature ones, leading to more efficient ways of predicting and preventing this complication.
Non-invasive Diagnostic Imaging
Although coronary angiography has long been the gold standard for coronary artery assessment, emerging non-invasive technologies are improving the detection of CAD while posing less risk to patients. For example, 64-slice multidetector computed tomography (CT)—a highly sensitive imaging technique—has become the preferred approach for diagnosing chest pain in low- or intermediate-risk patients who cannot undergo stress testing. By providing a coronary calcium score, the 64-slice system can also indicate the progress of coronary atherosclerosis or exclude CAD in emergency-room patients with equivocal acute chest pain.3
Cardiac Magnetic Resonance Imaging
Another emerging technology, cardiac magnetic resonance imaging (CMRI), uses a multimodal approach to detect coronary artery stenosis without the need for radiation exposure. This approach first evaluates myocardial perfusion at rest and during stress. It then performs delayed-enhancement imaging to detect MI and necrosis. In CAD patients undergoing stem cell therapy, such imaging assesses the ventricular response to therapy and the status of myocardial perfusion. In addition, CMRI evaluates left ventricular function and detects scar tissue, providing a thorough assessment of the patient’s cardiac health in less than one hour.
Minimally invasive technologies are revolutionizing the field of cardiovascular surgery. The goal of minimally invasive surgery is to produce the positive outcomes typical of established procedures while lessening the trauma of surgical access. Although coronary artery bypasses and valve replacements will always be needed, the range of options for these procedures continues to expand.
The degree of invasiveness of a cardiovascular surgical procedure depends on its incision size. Traditional access for cardiac procedures involves a full median sternotomy. However, with minimal-access surgery numerous kinds of incisions present less invasive alternatives, such as partial sternotomies, limited-access thoracotomies without rib spreading, subxiphoid and subdiaphragmatic approaches, and catheter-based techniques. Many of these operations are performed with robotic techniques and video thoracoscopy.4,5 As far as possible, access is obtained through a natural body orifice or blood vessel.6
Laparoscopy emerged in the 1980s for hernia repair, appendectomy, and cholecystectomy. With time, it was extended to almost every internal organ, including the heart. Post-operatively, laparoscopy reduces pain, shortens recovery, and allows a quicker return to normal activities. Nevertheless, the technique involves a steep learning curve, and the operative time itself may be increased.7
Robotic technology has been evolving as a minimally invasive means of treating cardiac ischemia and valve disease. The daVinci™ Surgical System (Intuitive Surgical, Inc., Sunnyvale, CA) was approved by the US Food and Drug Administration (FDA) in 2002 for a wide variety of surgical procedures. It involves a surgeon sitting at a special console whose movements are mimicked by four robotic interactive arms. Vision is aided by a high-resolution 3D endoscope. The system enables surgeons to perform cardiac revascularization through a minithoracotomy without cardiopulmonary bypass or to perform a complex mitral valve repair. Moreover, by allowing a hybrid approach involving more than one surgical procedure, i.e. stent placement and aortic valve replacement, robot-assisted procedures lower morbidity and mortality, especially in high-risk patients with combined CAD and aortic valve disease.8
As always, the physician’s main goal is to deliver the best available treatment while avoiding any possible harm. To protect the patient, every precaution must be taken, such as implementing preventive measures to address known risk factors, weighing the values and risks of new medications, considering the needs of the whole patient, and performing careful follow-up assessment.
As innovative techniques continue to evolve, they must be incorporated into clinical care. To accomplish this goal, cardiologists, cardiovascular surgeons, and other specialists must rely on a team approach. In becoming widely known, new treatments and diagnostic methods tend to generate interest and support for additional research, resulting in even more cardiovascular breakthroughs.