Where are the normal pacemaker and the backup pacemaker of the heart located?
Answer: The normal pacemaker of the heart is known as Sino- atrial (SA node) which is located in the right atrium of the heart, whereas, the backup pacemaker of the heart is known as Atrio- ventricular and it is situated in the centre of the heart along the right atrim (AV node) (Rhodes, 2008).
Why does this patient have a bradycardia?
Answer: The patient has bradycardia as a result of occlusion in the right coronary artery (Serrano Jr et al., 1999). Infarction in the right coronary artery is known to give rise to bradycardia.
What parts of the heart have the fastest and slowest conduction velocities?
Answer: The Purkinje fibres have the fastest conduction velocities whereas the AV bundles have the slowest conduction velocity. The Purkinje fibres have high numbers of gap junctions which lead to faster conduction velocity. On the other hand, AV bundles have less number of gap junctions resulting in lower conduction velocities.
Why was the CT scan ordered? What did the doctors suspect?
Answer: The purpose behind ordering the CT scan of the brain was to diagnose any possibility of stroke. The doctors suspected the probability of stroke.
What is the mechanism of the audible carotid bruit?
Answer: A carotid bruit is caused when there is a turbulent flow of blood in the artery occurring as a result of stenosis. The degree of stenosis determines the pitch, duration, and intensity of the bruit.
Explain the mechanism of the cardiac pacemaker.
Answer: An artificial pacemaker is a device which operates on battery. It is a small device powered by battery which does the function of natural pacemaker in the heart and helps in regulating the heart beat to its normal level. The artificial pacemaker has two parts, namely, the leads and the generator. The generator functions by stimulating the cardiac muscles to beat by producing electrical impulses. This generator can be planted beneath the skin through a minor incision. It is then connected to the heart directly with the help of some wires or leads. These wires or leads are also implanted in the heart along with the generator simultaneously. The electrical impulses are carried from the generator to the cardiac muscles via the leads or the wires. This ultimately helps in generating heart beat. These heart beats are very similar to the ones produced by the normal heart.
The patient presented with a sensation of heaviness in the chest with pain chest, dyspnea and light headedness. The patient was initially diagnosed with Myocardial Infarction, further tests were required for confirming the diagnosis. The patient was determined as a case which did not require thrombolytic medicines. The patient had bradycardia and a high blood pressure. On auscultation, carotid bruits were heard. The ECG showed a normal P wave, but a dissociated QRS wave. On further examination, the patient’s speech was found to be slurred and the left side of her face was found to be drooping down.
In order to rule out stroke, the patient was recommended a CT scan of the brain. The patient was simultaneously prepared for a pacemaker insertion. The initial diagnosis of myocardial infarction is correct. However, it is important to ensure if there is an underlying stroke. Adequate tests are needed to reach to the final diagnosis. The patient may need to undergo various lab tests and imaging tests in order to corroborate the findings with the assumptions. In this case, the patient seems to be not requiring anti thrombolytic therapy as the myocardial infarction was probably a result of embolic activity as a consequence of stroke.
A normal CT scan result may divert the line of treatment completely. Most likely result, however, still persists to be negative. A better taken history may be more helpful in reaching to the correct diagnosis. The patient was not asked about her past history and family history. These two questions may bring out more important points relevant to the case. These points may then help in confirming the diagnosis. They can also help in deciding the next set of tests which may be required to reach to the final conclusion of the case. Depending on the diagnosis and the test findings, the future course of action can be decided. Better taken case history, lab results and radiological tests will be helpful in the course of treatment. In case the patient tests positive for stroke in CT scan of brain, then it is also advisable to get an MRI scan done in order to rule out future complications. Controlling the rising blood pressure of the patient is yet another achievable goal that we need to work upon. Considering the age of the patient, it is important to provide proper education to the patient regarding the possible outcomes, complications, treatment options, alternatives and prognosis of the disease. She also needs education on taking care of herself in the time of emergency.
References
Rhodes, L. (2008). The Heart and Its Electrical System (1st ed.). Adult Congenital Heart Association. Retrieved from http://heart.ucla.edu/workfiles/Adult_Congenital/heartanditselectricalsystem.pdf
Serrano Jr, C., Bortolotto, L., César, L., Solimene, M., Mansur, A., Nicolau, J., & Ramires, J. (1999). Sinus bradycardia as a predictor of right coronary artery occlusion in patients with inferior myocardial infarction. International Journal Of Cardiology, 68(1), 75-82. http://dx.doi.org/10.1016/s0167-5273(98)00344-1
