The majority of senior-level undergraduate bachelor of science in nursing students enrolled at a private, comprehensive, liberal arts college reported being overwhelmed with advanced concepts of cardiac function, hindering their comprehension of the content. While pondering the electrical and pump aspect of cardiac function, the course faculty member was inspired to use a common referent to teach cardiac concepts. The purpose of the activity was to provide an active learning activity to simply demonstrate advanced cardiac function. The faculty member hoped to share her passion for cardiac function, reduce the students' anxiety about the material, and enhance learning.
THE TEACHING STRATEGY
The existing lesson plan included learning objectives that required an understanding of cardiac function:
1. Compare the various methods of hemodynamic monitoring (e.g., central venous pressure, pulmonary artery pressure, and arterial pressure monitoring).
2. Compare and contrast the continuum of normotension, prehypertension, hypertension, and hypertensive crisis.
3. Describe the action, side effects, and adverse reactions of antihyperlipidemics and peripheral vasodilators.
4. Describe the nursing care of a patient who has undergone cardiac surgery.
5. Summarize the pathophysiology, clinical manifestations, and treatment of myocardial infarction.
6. Compare and contrast diastolic and systolic heart failure, including pathophysiology and clinical manifestations.
7. Describe the management of patients with heart failure and develop a teaching plan.
8. Describe the assessment and management of patients with pulmonary edema.
9. Describe the management of patients with cardiogenic shock.
Existing teaching/learning strategies included reading assignments and theory application with a simulated lab experience titled Acute Coronary Syndrome and Acute Myocardial Infarction. The session began with the aquarium demonstration, which served for referral as concepts were introduced (e.g., preload with shock, afterload with hypertension).
The class consisted of 17 students. Evaluation of the teaching strategy was accomplished via a pretest and posttest using an audience response system and the students' self-report of content comprehension. The demonstration was not designed as a research project, and internal review board approval was not obtained.
The equipment used included an electrical cord and pump to represent the electrical aspect of the heart, a basic aquarium, a bottle of water labeled preload, and a plastic turtle labeled afterload to obstruct the pump. The demonstration required no special adaptation of the aquarium or pump, other than a means to obstruct the pump.
Students were asked to troubleshoot cardiac function problems demonstrated with an aquarium and pump. The following principles were demonstrated: First, the pump is electrical. Therefore, the pump must be plugged in to receive an electrical charge. Positive cations (such as magnesium and potassium) provide the electrical charge to the heart, which is represented by plugging the pump into the electrical outlet. To help students retain normal laboratory values, students were taught the 2 x 4 Rule: representing ideal serum magnesium and potassium levels for cardiac electrical function being a serum magnesium level of 2 mEq/L and serum potassium level of 4 mEq/L.
Second, the pump requires sufficient volume (preload) to produce cardiac output. This was demonstrated by adding water from a container marked preload. The pump cannot function effectively or efficiently with a volume deficit or fluid overload. This was demonstrated by either submerging the pump or lifting the pump out of the water. To link the demonstration to specific cardiac disease states and how they would look in the clinical setting, the demonstration was referred to as material was presented (e.g., the pump was submerged to represent cardiogenic shock). A discussion of clinical symptoms and anticipated treatment for volume overload followed.
Third, the pump must be able to accommodate resistance (afterload), which was demonstrated by using an obstacle to obstruct outflow (Figure 1). A discussion ensued concerning the indications and effects of vasodilator and vasoconstrictor medications.
Finally, the (plastic) fish does not die from lack of water, but lack of oxygen (perfusion) (Figure 2). A discussion ensued concerning symptoms and treatment of decreased cardiac perfusion.
STUDENT UNDERSTANDING
After using an aquarium and pump to demonstrate advanced cardiac function, students reported an understanding of concepts and terminology. The following is a sample question asked of students: The nurse is caring for a patient prescribed nitroglycerin for angina. The nurse knows nitroglycerin relieves the patient's chest pain by:
A. blocking sympathetic stimulation of the heart and reducing oxygen demand.
B. increasing contractility and consequent cardiac output.
C. blocking the a-delta pain fibers in the myocardium.
D. dilating the blood vessels and reducing preload.
The faculty member noted higher posttest scores after this demonstration, with students answering preload and afterload questions correctly. Student feedback was overwhelmingly positive. One student said, "The use of the aquarium brought the 'mystery of cardiac function' to actually understanding the how's and why's of heart issues. I pictured the 'stuck turtle' during the test and it helped me choose the right answer."
This demonstration has since been presented at two National Council Licensure Examination review programs where it received overwhelmingly positive feedback. To reinforce learning and develop test-taking skills, the faculty member has a tradition of asking the class to identify a useful concept learned in class and guiding the class, as a group, in developing that concept into an exam question. The class wrote the following exam question: To increase cardiac output, the nurse knows the goal of therapy is to (select all that apply):
A. increase preload.
B. decrease preload.
C. increase afterload.
D. decrease afterload.
CONCLUSION
This activity meets National League for Nursing recommendations for maintaining connections mentally and experientially (Halstead, 2007; Shultz, 2009). It requires an active search for meaning by the learner and the constructing of knowledge; learning is informal and incidental.
Importantly, the activity allows students to grasp the difficult concepts of cardiac function and apply them in a classroom activity. Participating students stated that they retained and recalled the demonstration during course examinations throughout the semester. Repeating this demonstration with more students and correlating pretest and posttest scores would be useful for evaluating this activity as an active learning method and an effective strategy to introduce students to advanced cardiac concepts.
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