From Ask Dr Wiki

Contents 1 General Considerations 2 General Programming 2.1 Rate Response 2.2 Tracking Rate 2.3 Mode Switching 3 AV Optimization 3.1 The Ritter Method 3.2 Simplified Mitral Inflow Method 3.3 The Iterative method 3.4 Use of Interatrial Conduction Times 3.5 References 3.6 References

General Considerations

1. Assess for ventricular fusion or pseudo fusion on electrogram. Look at Lead V1 and 1. If the R/S ratio is <1 in lead V1 or >1 in lead 1 then consider loss of left ventricular capture.
2. Assess degree of biventricular pacing. If <90% consider
   1. Conducted atrial tachyarrhythmia
   2. Atrial undersensing
   3. Ventricular oversensing
   4. Frequent Premature Ventricular Contractions

General Programming

Rate Response

Should be programmed on in patients with chronotropic incompetence, defined as failure to achieve max heart rate (220 - age) on a treadmill.

Tracking Rate

Set to a value of 140-150 bpm to ensure biventricular pacing at high heart rates and during exercise

Mode Switching

Should be enabled in all CRT patients. Also increase the LRL during mode switching to 70 bpm to increase the amount of ventricular pacing,

AV Optimization

Hemodynamic response to pacing may be affected by timing of the AV interval. Since the optimal AV delay is highly variable between subjects individual patients should be optimized. There are several methods used to optimize biventricular pacing

The Ritter Method

In 1994 a method developed by Ritter et al. had become established for optimizing the AV interval. The method for application of Ritter's method is Doppler echocardiographic measurement of the mitral inflow profile.

Step 1 The first step involves programming for the pacemaker a nonphysiologically short AV interval, followed by determination of QA_short. This value QA_short is the temporal interval between the ventricular contraction spike and the end of the A wave. QA_short designates the electromechanical delay between pacemaker stimulation and the beginning of the left ventricular systole (i.e., closure of the mitral valve).

Step 2 The next step is programming for the pacemaker a long AV interval, followed by determination of QA_long. This value QA_long is the temporal interval between the ventricular contraction spike and the end of the A wave. AV _long - QA_long defines the duration of the undisturbed maximal diastolic left ventricular filling.

AVopt=AVshort + [(AVlong + QAlong) - (AVshort + QA short)

which can be simplified

AVopt=AVlong - (QAshort) - (QAlong)

Simplified Mitral Inflow Method

A simplified method has been described that utilizes a single Doppler measurement of the mitral inflow. To calculate you must measure the interval between the end of the A wave and onset of the systolic component of mitral regurgitation, from the longest programmed AV interval with biventricular capture.

The Iterative method

Step 1 Program a “long” AV delay slightly shorter than the intrinsic AV interval
Step 2 Shorten the AV delay by 20 msec increments until the mitral valve A-wave is truncated by premature mitral valve closure
Step 3 Program the AV delay in 10 msec increments until the mitral valve A-wave truncation is eliminated.

Use of Interatrial Conduction Times

An EP catheter or LV lead is placed so that the proximal recording bipoles are in the inferior lateral CS (“3:00 to 6:00” in the left anterior oblique (LAO) fluoroscopy view. The RA lead is placed and pacing from the programmer/analyzer is performed at a rate five beats per minute faster than sinus rhythm. The IACT is measured and defined as the interval from the onset of atrial pacing to the beginning of CS deflection for the bipole in the most inferior lateral location (i.e., closest to 4:30 in the LAO view). Using the equation below, a the predicted PAV can be calculated.

PAV = 0.68 ∗ (IACT + 104) msec

References

1. Lane RE, Chow AW, Chin D, Mayet J: Selection and optimisation of biventricular pacing: The role of echocardiography. Heart 2004;90 (Suppl 6):vi10-16.
2. Interatrial Conduction Measured During Biventricular Pacemaker Implantation Accurately Predicts Optimal Paced Atrioventricular Intervals. J Cardiovasc Electrophysiol, Vol. 18, pp. 290-295, March 2007

References

1. Ritter Ph, Dib JC, Lelievre T: Quick determination of the optimal AV delay at rest in patients paced in DDD mode for complete AV block. (abstract). Eur J CPE 1994, 4(2):A163.
2. PACE 2006; 29:1416–1425