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An angiocardiogram was performed on an infant who had symptoms of breathlessness and it was found that he had a patent ductus arteriosus. Discuss the location and function of the ductus arteriosus in the fetus and relate it to the reason for the infant's breathlessness.

The ductus arteriosus is a shunt between the pulmonary trunk and the aorta in the fetus, which normally closes at birth. Breathlessness is due to the mixing of oxygenated and deoxygenated blood because the connection between the aorta and the pulmonary trunk remains slightly open.

A 14-year-old girl undergoing a physical examination prior to being admitted to summer camp was found to have a loud heart diastolic murmur at the second intercostal space to the left side of the sternum. Explain the reason for the loud heart murmur associated with this girl's condition.

The heart murmur is due to incomplete closing of the pulmonary valve.

A man enters the hospital complaining of chest pain. His history includes smoking, a stressful job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him that a heart attack is quite possible. What did the chest pain indicate? Why is this man a prime candidate for a heart attack?

His symptoms indicate angina pectoris, possibly due to either atherosclerosis or stress induced spasms of the coronary arteries. If the arteries are occluded, the heart muscle could be deprived of blood, and therefore oxygen. A heart attack could occur if the coronary vessels experience further occlusion.

An older woman complains of shortness of breath and intermittent fainting spells. Her doctor runs various tests and finds that the AV node is not functioning properly. What is the suggested treatment?

The suggested treatment is surgery to implant an artificial pacemaker.

A patient takes a nitroglycerin tablet sublingually for chest pain. Nitroglycerin acts directly on smooth muscle, producing relaxation and vessel dilation. How would this relieve chest pain?

Angina pectoris is thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium, with resultingdecreased oxygen being delivered to the cells. Because nitroglycerin acts as a vasodilator, blood flow is increased,promoting the delivery of oxygen to the cells.

A patient was admitted to the hospital with chest pains. On admission, his pulse was 110 and blood pressure was 96/64. According to his history, his normal pulse rate is usually between 80 and 88 and his blood pressure runs from 120/70 to 130/80. Explain why these changes in BP and HR occur.

Increased heart rate without maintaining his normal blood pressure is suggestive of reduced stroke volume. Both a drop in blood volume and a weakened heart could cause this, but the chest pains suggest heart damage. Failure of compensating mechanisms to maintain blood pressure suggest a serious decline incardiac output

A 55-year-old male was admitted to the hospital with heart failure. He complains of increasing shortness of breath on exertion and needing to sleep on three pillows at night. On physical assessment, the nurse determines that his ankles and feet are very swollen. Which of these symptoms reflect left-sided heart failure and which reflect right-sided heart failure?

Because the heart is a double pump, each side can initially fail independently of the other. If the left side fails,pulmonary congestion occurs. The right side of the heart continues to propel blood to the lungs, but the left side does not adequately eject the returning blood into the systemic circulation. Thus, blood vessels in the lungs become engorged with blood, pressure within them increases, and fluid leaks from the circulation into the lung tissue, causing pulmonary edema. Shortness of breath and difficulty breathing in a prone position may occur.
If the right side of the heart fails, peripheral congestion occurs. Blood stagnates within body organs, and pooled fluidsin the tissue spaces impair the ability of body cells to obtain adequate nutrients and oxygen and to rid themselves ofwastes. Edema is most noticeable in the extremities (feet, ankles, and fingers)

Asystole is the total absence of ventricular electrical activity. Explain why defibrillation would not be effective in this situation.

Defibrillation is accomplished by electrically shocking the heart, which interrupts its chaotic twitching by depolarizingthe entire myocardium. In this case, the ventricles are at a total standstill and defibrillation would not be effective.

A patient is prescribed a calcium channel blocker to prevent angina (chest pain), by decreasing the demand for oxygen. Explain why.

By preventing the influx of calcium ions into myocardial and vascular smooth muscle cells, calcium channel blockers inhibit the intracellular release of additional stores of calcium ions. A drug that inhibits the release of intracellular calcium ions decreases the force of myocardial contractility, thereby decreasing the oxygen demand.

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