Cath Lab Digest - May 2008 - (Page 6)

6 CLINICAL EDITOR’S CORNER MAY 2008 EKG. The computer-measured left ventricular end diastolic pressure (LVEDP) may be inaccurate, since the timing mark of the R wave from the EKG is out of synchrony with the pressure wave (please see Figure 1). For all simultaneous 2-pressure hemodynamic studies, or any study in which high accuracy is desired, we use tableside-mounted transducers. [Note: As of this month, ACIST has made available a connector to use your own transducer with the power injector. The next generation of this injector eliminates this problem with an incorporated transducer.] Recording Methodology I advocate using a standard routine for the three most common cath hemodynamic situations: left heart (aortic and LV only), right and left heart (2 simultaneous pressures with oxygen saturations and cardiac output), and right heart hemodynamics only. I know it is difficult to have all operators in the cath lab making measurements in the same way, but a common plan will help everybody and decreases procedure time. I reemphasize that communications from the operator’s field to the recording technologist should be clear in order to reduce frustration, confusion and errors. For example, we indicate chamber location, transducer number and then request a zero check. Each step is conveyed by verbal communications so the recording technologist knows where we are and what we are doing at the cath table. For accuracy, recording both phasic and mean tracings can be used and matched against the computer-generated numbers. Hemodynamics can be acquired as the catheter is moved through the right heart; for example, moving from right atrium to right ventricle to pulmonary capillary wedge and pulmonary artery (PA). Do not forget to obtain oxygen saturations during right heart catheterization to exclude unsuspected cardiac shunting and be used in a Fick O2 consumption calculation of cardiac output. Generally, four blood samples are required, one arterial, one from the inferior vena cava, one from the superior vena cava, and one from the PA. Should an increase in O2 saturation (step-up) exist of greater than 6% between chambers, one must ask whether or not there exists an atrial or ventricular level shunt. Cardiac output is then measured, followed by catheter pullback data recording from wedge to PA, right ventricle (RV) and right atrium (RA). Interpretation of the Pressure Waveforms It is important to review the waveforms as you collect them. The pressure waves should make sense for the catheter location, cardiac rhythm and clinical situation. The pressure waveform should be timed correctly with the EKG and should be of appropriate scale. For example, does an arterial pressure of 60/40 with a heart rate of 80bpm make sense in a perfectly comfortable, awake patient who is talking to you? First, check the patient. Then, check the scale factors on the recorder, then the connections and tubings again, and whether or not the pressure transducer is connected to the left- or right-sided catheter. Errors like this are a common source of confusion among inexperienced personnel. Unusual waveforms should correlate to pathophysiology. If not, suspect some error in the recording technique, such as a loose connection, an air bubble, clot in the line, a damped or kinked pressure tube or catheter, or a wrong recording scale and so on. These checkpoints are necessary to record good quality hemodynamics. Simultaneous Right and Left Heart Hemodynamics Usually, right heart hemodynamics are performed in conjunction with left heart hemodynamics to obtain a complete assessment of myocardial, pulmonary and valvular function. Normally, when performing simultaneous right and left heart hemodynamics, we place the right heart catheter through its normal route to the PA in the manner Figure 1. Panel A. Left ventricular and aortic pressures measured from table side transducers. The vertical yellow lines indicate left ventricular end diastolic pressure (LVEDP) and timing to EKG. Note the delay in aortic pressure due to pressure transmission from the femoral arterial sheath side arm. The computer has placed ‘d’ on aortic diastolic pressures and ‘e’ on LVED pressures. The ‘e’ position varies, but is mostly close to the true LVEDP. Scale 0-200mmHg. described above. After cardiac output is obtained, we insert the pigtail catheter in the LV via the femoral artery sheath and obtain LV hemodynamics and simultaneous wedge pressure to gauge mitral valve function. On pullback of the right heart catheter, we measure simultaneous right and left ventricular pressures in patients suspected of having constrictive or restrictive physiology. Finally, for all left heart hemodynamics, compare LV and femoral artery pressure (from the arterial sheath side arm) to evaluate aortic valve disease during pigtail catheter pullback. Right and left heart catheterizations performed in this manner will provide a complete hemodynamic assessment in 95% of all cases and provide an accurate understanding of aortic, mitral, tricuspid, and pulmonary valve disease with minimal extra maneuvers. These protocols have been described elsewhere.1 Finally as you review your own procedures in the cath lab, see where you can improve the precision, organization, clarity, and operational protocols to obtain better hemodynamic data. ■ Figure 1. Panel B. Left ventricular pressure recorded with an ACIST transducer, demonstrating delay in pressure relative to EKG. The R wave precedes the LVEDP by almost 100msec. Manual selection of LVEDP is required. 1. Hemodynamic Data. In: Kern MJ. The Cardiac Catheterization Handbook. 4th ed. St. Louis, MO: Mosby; 2003:126-217. Reference http://www.tzmedical.com http://www.tzmedical.com

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Cath Lab Digest - May 2008 The King Faisal Specialist Hospital and Research Centre Cell Therapy in the Cath Lab for Heart Failure: A Look at MyoCell® Therapy and the SEISMIC Trial Performance Improvement Strategies Speed Up Treatment Times in the Management of ST-Elevation Myocardial Infarction (STEMI) Patients Contents Clinical Editor’s Corner Commentary: Performance Improvement Strategies Speed Up Treatment Times in the Management of ST-Elevation Myocardial Infarction (STEMI) Patients Ask the STEMI Expert Comparing Drug-Eluting Stents and Bare-Metal Stents SICP: The Ten-Minute Interview with… Christopher Kambak, RT(R) Cardiac Cath Lab Economics in a Public Hospital of a Developing Country Keeping Your Heart & Vascular Employees: Proven Ideas for an Effective Retention Plan Unspoken Words Ask the Clinical Instructor Society of Invasive Cardiovascular Professionals Meetings Calendar Education Center What Do You Think? Clinical & Industry News Classifieds Advertisers Index

Cath Lab Digest - May 2008

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