Cardiology Week 1 Summary

Question 1

What is the definition of normal and hypertension based on ambulatory blood pressure monitoring (ABPM)?

Definition of normal:
One of the unresolved issues in ambulatory monitoring is the definition of what constitutes normal and elevated BP. A meta-analysis of normotensive subjects found mean 24-hour and daytime values to be 118/72 and 123/76 mmHg, respectively; the former is lower since the BP normally falls with sleep.

Most experts agree that 24 hour blood pressure <130/80 mmHg is probably normal, and 135/85 mmHg is probably abnormal.

Definition of hypertension:
The diagnosis of hypertension using on ABPM depends on the time span over which it is interpreted:

  • 24-hour average above 135/85 mmHg
  • •Daytime (awake) average above 140/90 mmHg
  • Nighttime (asleep) average above 125/75 mmHg

A daytime ambulatory average BP below 135/85 is infrequently associated with left ventricular hypertrophy (LVH) and almost always represents normotension. An echocardiogram can be used to ascertain the possible presence of significant hemodynamic stress or LVH if the daytime average is between 135/85 and 140/90.

Question 2

When are “pauses” reported on Holter a concern?

Pauses of up to 2 seconds are common in the general population and are especially common in the elderly. These pauses are usually benign. The most frequent causes of pauses are blocked (non-conducted) premature atrial contractions (PACs), sinus arrhythmia, temporary pauses in the rate of discharge of the sinoatrial node (i.e., sinus pauses) and medication-induced pauses.

Pauses of longer than 2 seconds, especially when frequent and accompanied by episodes of significant bradycardia (less than 40 beats per minute), suggest the possibility of sick sinus syndrome.

Longer pauses (3 seconds or greater) are more likely to be symptomatic and pathologic. Pacemaker implantation should be considered if there are symptoms of syncope, dizziness, or severe fatigue in association with prolonged pauses (i.e. 3 seconds or more) or with persistent bradycardia.

Grauer K, Leytem B. A systematic approach to Holter monitor interpretation. Am Fam Physician. 1992 Apr;45(4):1641-8

Question 3

What is the differential diagnosis of continuous thoracic murmurs and their origin?

In the order of descending frequency…

Diagnosis Key findings
Cervical venous hum Maximal in R supraclavicular fossa & can radiate to contralateral area or below clavicle. Disappears on compression of jugular vein.
Hepatic venous hum Often disappears with epigastric pressure
Mammary souffle Disappears upon pressing hard with stethoscope, or patient moving into upright position
Patent ductus arteriosus (Gibson’s murmur) Loudest at the 2nd left ICS. Machinery murmur.
Coronary arteriovenous fistula Loudest at the lower sternal border.
Ruptured aneurysm of sinus of Valsalva Loudest at the upper right sternal border, sudden onset
Bronchial collaterals Associated signs of congenital heart disease
High grade coarctation Brachial/pedal arterial pressure gradient
Anomalous left coronary artery arising from pulmonary artery
Anomalous pulmonary artery arising from aorta
Pulmonary artery branch stenosis Heard outside the area of cardiac dullness
Pulmonary AV fistulas Heard outside the area of cardiac dullness
ASD with mitral stenosis or atresia Altered by Valsalva manoeuvre
Aortic-arterial fistulas
Superior caval syndrome due to syphilitic aneurysmal dilatation of aortic root and mediastinitis Systolic accentuation; 2nd and 3rd right ICS

Sapira led. p.304

Question 4

What is considered a positive hepatic jugular reflux (HJR) or abdominal jugular reflux (AJR)?

Initially described by William Pasteur in 1885 and thought to be specific for tricuspid regurgitation (TR). This test involves distension – with or without pulsation – of the superficial veins of the neck, occurring when firm pressure (35 mmHg) is exerted over the liver or mid-abdomen which is non-tender (to avoid Valsalva maneuver). Pressure is in the direction of the spinal column, should last for one minute, and is independent of the movement of respiration.

The test is said to be positive when there is a venous rise of more than 4 cm after the patient has two spontaneous breaths.

Initial compression of the abdomen in a patient who does not guard or perform the Valsalva maneuver, usually produces an initial rise because of forced increase in venous return. But at the end of two spontaneous breaths, the initial Valsalva maneuver effect will no longer be present and the abdominal compression acts as a tourniquet and impedes venous return to the right heart.

Pathophysiology …
In congestive heart failure, there is increased sympathetic outflow. Systemic venous hypertension causes the venous system, the right atrium and right ventricle to be inelastic, tight and non-compliant, i.e. increase in tone-volume. On compression of the abdomen, a unit of pressure exerted in the smaller system is transmitted to the larger system.

Differential diagnosis:…

  1. Heart failure, including right heart “backward” failure
  2. Constrictive pericarditis
  3. Pericardial tamponade
  4. Tricuspid insufficiency
  5. IVC obstruction

False positive non-cardiac causes of positive HJR: …

  1. Small vital capacity, inability to tolerate the upward movement of the diaphragm
  2. Increased blood volume
  3. Increased sympathetic stimulation e.g. nervousness, pain, or acute infarct
  4. Abdominal compression exaggerates the amplitude of the jugular pulsations without actually raising the upper levels. May give a false impression of a rise in venous pressure.
  5. Obstruction of the SVC below the junction of the azygous with the SVC also elevates venous pressure. Abdominal compression prevents the jugular blood from emptying freely into the azygous, thus further elevating the jugular pressure.

Sapira 1ed. p. 361-363

Constant J. Bedside Cardiology. 4th ed. 1993 p. 75-76 Fig. p. 76

Question 5

What is the point of maximal impulse (PMI) considered enlarged or sustained?

Often students and residents quoted coin sizes as being reference standards (e.g. dimes and quarters). However, it does not take into account the different body sizes (e.g. mini-me vs. Yao Ming). Not to mention there are non-North Americans who may not be familiar with the size of a quarter or dime.

A better way is to use the patient’s body landmark as an internal reference.

A PMI is considered enlarged when it is bigger than one intercostal space, i.e. when the PMI can be felt in two or more intercostal spaces.

A PMI is considered sustained when the PMI can be felt more than 2/3 of the systole or if PMI reaches or exceeds the second heart sound.

Subscribe to Pearls

Uncle Sam wants you to subscribe to Medical Pearls

Subscribe today! It’s always free, and you can easily unsubscribe at any time. We will never share your email address. Subscribe to...

Multiple Pearls
Cardiology Pearls
Endocrinology Pearls
Hematology Pearls
Nephrology Pearls
Rheumatology Pearls
Transplant Pearls
General Internal Medicine Pearls
Instructor Pearls

Subscribe to receive your pearls today—it's free!