Term
| What are the causes and differences of Overdamped and Underdamped pressures? |
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Definition
On the pressure tracings, narrow spikes or overshoot in the ventricular (right and left) pressure suggests underdamping (i.e., a too-sensitive pressure system. Wide, rounded waves indicate overdamping (i.e., not sensitive enough), usually produced by a problem in the fluid path to the transducer or a transducer that is not calibrated correctly.
Possible Causes:
Overdamping; Bubble or clot in line or transducer, Small lumen of tubing system, Soft or compliant tubing, Loose catheter connection, Kink in catheter
Underdamping; System tubing too stiff, System tubing too long, Hyperdynamic state, Catheter in turbulent jet |
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Term
| What is the appropriate use of PCWP? |
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Definition
-Closely approximates LA pressure
-Overestimates LA pressure in patients with acute respiratory failure, COPD with pulmonary hypertenstion, pulmonary venoconstriction, or LV failure with volume overload.
-Usually sufficient to estimate LV filling pressure p 134-135 |
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Term
| What are the appropriate measures that need to be taken to obtain an accurate PCWP? |
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Definition
| a) The operator should position the catheters correctly and verify the position through waveform, oximetry (oxygen saturation >95%), and fluroscopy. b) A stiff, large-bore end-hole catheter should be used. c) Connect the catheter to the pressure manifold with stiff, short pressure tubing. d) The system should be thoroughly flushed before accepting wedge pressure. e) For mitral valve area determinations the operator should correct for the time delay (i.e., phase shift the PCW pressure v wave to match the LV downstroke). |
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Term
| Describe the Wheatstone bridge principle? |
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Definition
| The Wheatsone bridge principle is utilized by the strain gauge. In the gauge the pressure is transmitted through a port that acts on a diaphragm. The diaphragm is a attached to a plunger and the pressure exerted on the diaphragm causes it to stretch that in turn causes wires to stretch. This causes an increase in the resistance of the wires. This causes the resistances to become unbalanced and current will then flow accross the ouput terminals. Because the diaphragm has to be stretched a certain volume of fluid must actually move through the catheter and tubing to produce a recorded pressure. |
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Term
| What pressures would be recorded as well as what scale and paper speed would be used to evaluate the severity of AS, AI, MS, MR? |
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Definition
| AS - record pressures in LV and AO with a paper speed of 100mm/sec and a scale of 0-200mmHg, AI - recored pressures in LV and AO with a paper speed of 100mm/sec and a scale of 0-200mmHG, MR - record pressures in the LV and PCW with a paper speed of 100mm/sec and a scale of 0-50mmHg, MS - record pressures in the LV and PCW with a paper speed of 100mm/sec and a scale of 0-50mmHg |
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Term
| Describe the pathway in which blood travels from the heart, throughout the body, and back to the heart. |
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Definition
| As blood leaves the LV it passes upward and deep to the pulmonary trunk and is now called ascending aorta. The ascending aorta gives off two coronary branches to the heart muscle. The the aorta turns to the left and because the aortic arch. It then descents to the level of the 4th vertebra as the descending aorta. It then passes through the diaphragm and divides into two common iliac arteries that carry blood to the lower extremities. Each section of the aorta gives off arteries that continue to branch into distributing arteries leading to organs and finally into the arterioles and capillaries that servies the systemic tissues. Blood is then returned to the heart through the system veins. All the veins of the systemic circulation flow into either the SVC or IVC or the Coronary sinus. They in turn empty into the right atrium. |
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Term
| Explain and identify the difference between damping and ventricularization. |
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Definition
| In ventricularization is a fall in diastolic pressure only (the systolic pressure is preserved but diastolic pressure is reduced). In damping is a fall in overall catheter tip pressure (both systolic and disatolic pressures are reduced) |
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Term
| Name the changes that occur to the fetal circulation after birth. |
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Definition
| At birth: a) The umbilical arteries vasoconstrict shut and atrophy to become the medial umbilical ligaments. b) The umbilical vein vasoconstricts shut and becomes the round ligament of the liver. c) The placenta is delivered by the mother as "after-birth" d) The ductus venosus vasoconstricts shut and becomes the ligamentum venosum, a fibrous cord in the liver. e) The foramen ovale normally closes shortly after birth to become the fossa ovalis, a depression in the interatrial septum. f) The ductus arteriosus closes by vasoconstriction and atrophies and becomes the ligamentum arteriosum. |
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Term
| Name some adverse affects of coronary injections. |
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Definition
| Older high-osmolar contrast agent had a number of potentially deleterious effects during coronary injection that include the following: a) Transient (10 to 20 sec) hemodynamic depression marked by arterial hypotension and elevation of the LVEDP, b) ECG effects such as T-wave inversion or peaking of inferior leads, sinus slowing or arrest, and prolongation of the PR, QRS, and QT intervals c) significant arrhythmias d) myocardial ischemia owing to interruption of O2 delivery or inappropriate arteriolar vasodilatation (coronary "steal") e) allergic reaction and f) cumulative renal toxicity (also provocation of myocardial ischemia) |
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Term
| What is the correct method in which a pressure waveform is created? |
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Definition
| A pressure wave is created by cardiac muscular contaction and is transmitted from the vessel or chamber along a closed, fluid-filled column (catheter) to a pressure transducer, which converts the mechanical pressure to an electrical signal that is displayed on a video monitor. |
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Term
| List the indications for the Right heart cath. |
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Definition
| Right heart catheterization is indicated in patients with a history of dyspnea, valvular heart disease, or intracardiac shunts |
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Term
| What are the complications associated with a right heart cath? |
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Definition
| The most common problem with right-sided heart catheterization is arrhythmia resulting from stimulation of the right ventricular outflow tract, which may result in AV block, or, rarely, right bundle branch block. |
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Term
| What is the formula for Fick CO? |
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Definition
| O2 consumption (ml/min)/AVO2 difference (ml O2/100ml blood) x 10 |
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Term
| Name the catheters used during an Aortic Stenosis case. |
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Definition
| Pigtail ventriculography catheter, Left or Right Amplatz catheter, Right Judkins catheter, multipurpose catheter and specially designed catheters that have been reported in literature |
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Term
| What are the appropriate points to remember when crossing the Aortic Valve? |
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Definition
| Points to remember for Crossing the AV with guidwires are; a) Adequate heparinization (5000-U bolus) should be maintained. Frequent catheter flushing is performed. b) A maximal time of 3 minutes per crossing attempt is required before wire withdrawal, wiping, and flushing of the catheter. c) A 0.035-inch guidewire may be insufficiently stiff to support the catheter on crossing severly deformed, calcific aortic valves, and a 0.038-inch guidewire should be substituted. Large catheters that accept this size of wire should used. d) Guidewire configurations that lead to the coronary ostia should be avoided to prevent dissection of the coronary arteries, which would complicate this otherwise benign maneuver. e) Manipulation of the wire should be gentle to avoid damaging the valve, lifting atheromas, or causing a perforation of the cusps or aortic root. |
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Term
| What are the consequences if a steady state is not achieved during a Fick Cardiac Output determination? |
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Definition
| If a steady state is not achieved because of anxiety, dyspnea, or any condition in which measurement of oxygen is spuriously elevated, an abnormally high CO is calculated. Conversely, shallow breathing (alveolar hypoventilation), commonly seen with oversedation, results in a falsely low oxygen consumption and low CO determination |
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Term
| State the use of the proximal port, distal port, thermistor, and balloon on the Swan Ganz catheter in Thermodilution CO determinations. |
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Definition
| The proximal port, located 30 cm from the tip, is used for RA pressure measurement and for rapid infusion of the saline during CO determination, the distal end hole is used for pressure measurement, and the lumen is used to inflate the balloon. A thermistor at the distal tip measures the blood temperature. The balloon aids in catheter positioning and facilitates PCWP measurement. |
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Term
| What are the difference between the cardiac output techniques? |
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Definition
| The Fick technique is the most accurate method of assessing CO, particularly in patients with low CO. This requires the patient to breath at a steady state. The Thermodilution method uses cold saline as the indicator (Indocyanine method is no longer used). CO is determined by a rapid injection of 10ml of cold saline and the thermistor on the swan catheter measures the temperature change in the blood (temp/time) to determine the CO. The Angiographic CO provides the best estimate of CO through a stenotic valve when any degree of regurgitation is present. Errors in stroke volume computation are increase with enlarged ventricles. |
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Term
| What are the normal ranges for intracardiac and intravascular pressures? |
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Definition
Right Artrium = mean of 2 to 6 mmHg
Right Ventricle = Systolic 20 to 30 mmHg, Distolic 0 to 5 mmHg, End-Diastolic 2 to 6 mmHg
Pulmonary Artery = Systolic 20 to 30 mmHg, Diastolic 8 to 12 mmHg, Mean 10 to 20 mmHg
PCW = mean of 4 to 12 mmHg
Arterial = Peak Systolic 100 to 140 mmHg, End-diastolic 60 to 80 mmHg, Mean 70 to 90 mmHg |
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Term
| What are the normal ranges and unit of measurement for vascular resistance (SVR, SVRI, PVR, PVRI)? |
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Definition
| SVR = 1,170 +/- 270 dynes/sec/cm^-5, SVRI = 2,130 +/- 450 dynes/sec/cm^-5, PVR = 67 +/- 30 dynes/sec/cm^-5, PVRI = 123 +/- 54 dynes/sec/cm^-5 |
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Term
| What events occurs during the different segments of the ECG? |
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Definition
-P wave – atrial deploarization
-QRS – ventricular depolarization
-T wave – rapid phase of ventricular repolarization
-ST segment – plateau phase of ventricular repolarization. |
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