Invading the Human Heart

by Hanson Tam

Pathogenic viruses and bacteria routinely invade the human body. But so do curative treatments ranging from drugs to surgery. In a society in which invasion connotes violence and injury, many people avoid acknowledging the intrusive nature of medicine. Awareness is important; it encourages the development of less invasive yet equally effective procedures. Such has characterized cardiac surgery’s rapid advances in treating coronary artery disease (CAD), the leading cause of death worldwide.1 As cardiologists and cardiac surgeons explore new options, they seek the right balance between invasiveness and effectiveness.

CAD is the narrowing of the coronary arteries most often due to cholesterol-rich plaque accumulating along artery walls. The narrowing limits the amount of blood and nutrients the heart receives. A heart attack occurs when a coronary artery is completely blocked and the dependent heart muscle dies. While administering drugs such as nitroglycerin (which dilates blood vessels) and beta-blockers (which reduce blood pressure) constitutes the least intrusive treatment, drugs are not sufficient in many cases of CAD.2

Percutaneous coronary intervention (PCI), which includes stenting, represents the next level of invasiveness. It was first performed in 1977.3 Not technically surgery, PCI involves threading a long thin catheter through blood vessels to reach the afflicted, plaque-laden location. The cardiologist inflates a balloon to widen the artery and then reinforces the artery with a tubular stent. PCI remains as an appealing, minimally invasive solution when only one or two blood vessels need attention. Beyond that, however, it is not nearly as effective as the open-heart procedure developed over a decade earlier.4

1962 marked the invention of coronary artery bypass graft (CABG) surgery, the gold standard for CAD treatment to this day.1 In this most invasive procedure, the surgeon harvests a nonessential artery or vein from the patient and joins one end of that vessel to the aorta and the other end to the afflicted coronary artery just below the blockage. CABG requires a doctor to saw open the sternum, temporarily stop the heart, and pump and oxygenate blood through an external machine. This process is risky and traumatic to the body; however, for severe cases of the disease, graft surgery leads to higher long-term survival rates than does regular stenting.4

Improvements in CAD treatment have tended to be variations on PCI and CABG. To address the reclogging of stented arteries in up to 30% of PCI cases, scientists created a variety of drug-eluting stents (DES) in which cells cannot grow.5 Yet DES often still require reintervention. On the other hand, advancements in surgical technique have yielded less invasive forms of CABG that can be performed on beating hearts, require only small incisions, and can be executed by robotic arms. Such techniques are significantly less invasive and promote faster recovery than traditional CABG while retaining the safety and efficacy of the approach.1

At the current frontier of CAD surgery lies hybrid coronary revascularization (HCR). Although this procedure was first performed in 1996, its use has increased only recently. HCR is novel in that both PCI and CABG are done as a single treatment. The rationale is to combine the benefits from both procedures, namely CABG’s superiority when treating the main coronary artery and PCI’s effectiveness at treating smaller arteries that branch off from the main artery.1 HCR has preliminarily been shown to be at least as safe and effective as conventional CABG—perhaps even leading to a faster recovery. To make conclusive evaluations, however, more studies comparing HCR with existing procedures are required.1,6,7

The surgical treatment of CAD is especially exciting because it is in a stage of refinement. Physicians are striving to retain the benefits of invasive bypass surgery while minimizing the side effects of large incisions and cardiac arrest. Physical invasion of the body remains necessary for the foreseeable future. However, as researchers weigh the effectiveness and invasiveness of different treatment options, heart doctors will be able to personalize care based on the unique aspects of each individual.

Hanson Tam ’19 is a freshman in Matthews Hall.

Works Cited

  1. Ejiofor, J. et al. Prog. Cardiovasc. Dis. [Online] 2015, doi:10.1016/j.pcad.2015.08.012 (accessed Oct. 4, 2015).
  2. Parmet, S. et al. JAMA 2004, 292, 2540.
  3. Hessel, E. In Cardiac Anesthesia: Principles and Practice, 2nd ed.; Estafanous, F. et al., Eds.; Lippincott Williams & Wilkins: Philadelphia, PA, 2001, 3-36.
  4. Rosengart, T. et al. In Surgery: Basic Science and Clinical Evidence, 2nd ed.; Norton, J. et al., Eds.; Springer: New York, 2008, 1627-1635.
  5. Rinfret, S. et al. J. Am. Coll. Cardiol. 2015, 65, 2508-2510.
  6. Harskamp, R. et al. J. Am. Coll. Surgeons 2015, 221, 326-334.
  7. Zhu, P. et al. J. Cardiothorac Surg. [Online] 2015, 10, doi:10.1186/s13019-015-0262-5 (accessed Oct. 4, 2015).

 

 

 

Categories: Fall 2015

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