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Coronary blood flow velocity during apical versus septal pacing1
International Journal of Cardiology 66 (1998) 203–205
Coronary blood flow velocity during apical versus septal pacing 1 Theofilos M. Kolettis*, Zenon S. Kyriakides, Dimitrios Th. Kremastinos 2 nd Department of Cardiology, Onassis Cardiac Surgery Center, Athens, Greece Received 25 February 1998; accepted 14 July 1998
Abstract Previous studies have indicated that ventricular asynchrony may significantly affect resting coronary blood flow velocity. Our study argues against this hypothesis, as comparable left anterior descending blood flow velocities were found during three pacing modalities, associated with varying degrees of asyncbrony: (a) atrial pacing, (b) atrioventricular (AV) sequential pacing from the right ventricular apex and (c) AV sequential pacing from the proximal right ventricular septum. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Ventricular asynchrony; Pacing; Coronary blood flow velocity
1. Introduction Right ventricular apical pacing results in asynchronous ventricular contraction [1] and may decrease coronary artery blood flow [2–4]. Pacing from the proximal septum results in less asynchrony [5], however, the effects of such pacing on coronary blood flow are not known.
2. Materials and methods Patients with normal 12-lead electrocardiogram (ECG), normal left ventricular function and normal coronary arteries were studied. All medications were discontinued 72 h prior to the study and informed consent was obtained. The study was approved by the Institutional Ethics’ Committee. *Corresponding author: Tel.: 130-1-9406-184, 130-1-939-3372; Fax: 130-1-939-3331, 130-1-939-3373; E-mail: [email protected] 1 Presented, in part, at the 17th Panhellenic Congress of Cardiology, October 24-26, 1996, Athens, Greece.
Two temporary pacing electrodes were positioned in the right atrium and the right ventricle. Three pacing modes were applied in a random sequence: (a) atrial pacing, (b) atrioventricular (AV) sequential pacing from the right ventricular apex and (c) AV sequential pacing from the proximal right ventricular septum. During septal pacing, the electrode was placed high in the outflow tract and was pulled back until the tip pointed in a lateral direction on a posteroanterior fluoroscopic projection, as previously described [6] (Fig. 1). The position was confirmed in the right and left anterior oblique projections. Based on previous reports [4], each pacing mode lasted for 5 min, with 5 min intervals between each mode. Pacing rate was 15 beats per minute above the resting sinus rate. To prevent fusion beats, AV-delay was set at 60% of the PR interval during sinus rhythm. The duration of the QRS complex was measured from hard copy recordings (at paper speed 100 mm / sec), using hand-held calipers. Coronary blood flow velocity was recorded during the last minute of each pacing sequence, using a steerable Doppler guidewire (FloWire, Cardiometrics,
0167-5273 / 98 / $19.00 1998 Elsevier Science Ireland Ltd. All rights reserved. PII: S0167-5273( 98 )00215-0
T.M. Kolettis et al. / International Journal of Cardiology 66 (1998) 203 – 205
204
Inc., Mountain View, CA, USA), positioned in the proximal part of the left anterior descending coronary artery, as previously described [7]. Average peak velocity and diastolic to systolic velocity ratio were measured. To prevent variations in coronary artery diameter, vasodilation was induced by intracoronary injection of 250 mg nitroglycerin, as reported previously [8]. Arterial pressure and the ECG were continuously recorded. Comparison between variables was performed using analysis of variance for repeated measures, followed by Tukey’s HSD test. Statistical significance was defined at an alpha level of 0.05.
3. Results Seventeen patients (mean age 56610 years, 14 male) were studied. There were no procedure-related complications. Although systolic pressure was lower during apical compared to atrial pacing, mean blood pressure remained unchanged (Table 1). No significant differences were found in the average peak velocity or in diastolic to systolic velocity ratio (Table 2).
4. Discussion Fig. 1. Anteroposterior fluoroscopic view of the flow-wire at the proximal part of the left anterior descending coronary artery. One temporary electrode catheter is seen in the right atrium and one at the apex of the right ventricle (panel A) or at the high right ventricular septum (panel B).
Compared to atrial pacing, ventricular apical pacing may be associated with lower resting coronary blood flow velocity [3]. This may be secondary to the altered ventricular depolarization sequence [2,3].
Table 1 Blood pressure and QRS duration during pacing Variable SBP (mmHg) DBP (mmHg) MBP (mmHg) QRS (ms)
AAI
DDD Apex
DDD Septum
a
143613
8368
8467
10469 8666
147614
139614
F value
p value
6.9
0.0031
8468
0.10
0.37
10269
10469
1.15
0.32
15665
15165
N /A
0.014 b
AAI, Atrial pacing; DDD Apex, Atrioventricular sequential pacing from the right ventricular apex; DDD Septum, Atrioventricular sequential pacing from the proximal right ventricular septum; SBP, Systolic blood pressure; DBP, Diastolic blood pressure; MBP, Mean blood pressure; N /A, non applicable. a p,0?05 compared to AAI pacing. b post-hoc comparison p value.
T.M. Kolettis et al. / International Journal of Cardiology 66 (1998) 203 – 205
205
Table 2 Coronary blood flow velocity parameters during pacing Variable
AAI
DDD Apex
DDD Septum
F value
p value
APV DSVR
25.369.0 2.3560.83
24.569.0 2.2560.46
25.8610.5 2.0660.45
1.09 1.81
0.34 0.17
AAI, Atrial pacing; DDD Apex, Atrioventricular sequential pacing from the right ventricular apex; DDD Septum, Atrioventricular sequential pacing from the proximal right ventricular septum; APV, Average peak velocity; DSVR, Diastolic to systolic velocity ratio.
Animal data have suggested significant variations in coronary blood flow velocities (predominantly in the left anterior descending artery) during different degrees of pacing-induced asynchrony [4]. In the present study, we report constant resting coronary blood flow velocity during short-term pacing from two ventricular sites, previously [5] shown to result in varying degrees of asynchrony. This finding may contribute to the on-going clinical evaluation of the optimal ventricular pacing site. Possible limitations of our study are the following: (a) We examined only resting coronary blood flow and not coronary blood flow during maximal hyperemia. Nonetheless, maximal hyperemia may abolish potential variations in resting coronary blood flow [3,4]. (b) Although we measured velocity and not actual flow, this limitation was largely overcome by nitroglycerin-induced vasodilation [8]. In summary, short-term apical and proximal septal pacing are associated with comparable resting blood flow in the left anterior descending coronary artery.
Acknowledgements The authors are indebted to Mrs. Panayiota
Panagaki, RN, and Mrs. Efthalia Tzanalaridou, BSc, for their valuable contribution to this work.
References [1] Aoyagi T, Iizuka M, Takahashi T, et al. Wall motion asynchrony prolongs time constant of left ventricular relaxation. Am J Physiol 1989;257:H883–90. [2] Ono S, Nohara R, Kambara H, Okuda K, Kawai C. Regional myocardial perfusion and glucose metabolism in experimental left bundle branch block. Circulation 1992;85:1125–31. [3] Kolettis TM, Kremastinos DT, Kyriakides ZS, Tsirakos A, Toutouzas PK. Effects of atrial, ventricular and atrioventricular sequential pacing on coronary flow reserve. PACE 1995;18:1628– 35. [4] Amitzur G, Manor D, Pressman A, et al. Modulation of the arterial coronary blood flow by asynchronous activation with ventricular pacing. PACE 1995;18:697–710. [5] Rosenqvist M, Bergfeldt L, Haga Y, Ryden J, Ryden L, Owall A. The effect of ventricular activation sequence on cardiac performance during pacing. PACE 1996;19:1279–86. [6] Buckingham TA. Right ventricular outflow tract pacing. PACE 1997;20:1237–42. [7] Segal J, Kern MJ, Scott NA, et al. Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty. J Am Coll Cardiol 1992;20:276–86. [8] Claeys MJ, Vrints CJ, Bosmans J, Krug B, Blockx PP, Snoeck JP. Coronary flow reserve during coronary angioplasty in patients with a recent myocardial infarction: relation to stenosis and myocardial viability. J Am Coll Cardiol 1996;28:1712–9.
Coronary blood flow velocity during apical versus septal pacing 1 Theofilos M. Kolettis*, Zenon S. Kyriakides, Dimitrios Th. Kremastinos 2 nd Department of Cardiology, Onassis Cardiac Surgery Center, Athens, Greece Received 25 February 1998; accepted 14 July 1998
Abstract Previous studies have indicated that ventricular asynchrony may significantly affect resting coronary blood flow velocity. Our study argues against this hypothesis, as comparable left anterior descending blood flow velocities were found during three pacing modalities, associated with varying degrees of asyncbrony: (a) atrial pacing, (b) atrioventricular (AV) sequential pacing from the right ventricular apex and (c) AV sequential pacing from the proximal right ventricular septum. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Ventricular asynchrony; Pacing; Coronary blood flow velocity
1. Introduction Right ventricular apical pacing results in asynchronous ventricular contraction [1] and may decrease coronary artery blood flow [2–4]. Pacing from the proximal septum results in less asynchrony [5], however, the effects of such pacing on coronary blood flow are not known.
2. Materials and methods Patients with normal 12-lead electrocardiogram (ECG), normal left ventricular function and normal coronary arteries were studied. All medications were discontinued 72 h prior to the study and informed consent was obtained. The study was approved by the Institutional Ethics’ Committee. *Corresponding author: Tel.: 130-1-9406-184, 130-1-939-3372; Fax: 130-1-939-3331, 130-1-939-3373; E-mail: [email protected] 1 Presented, in part, at the 17th Panhellenic Congress of Cardiology, October 24-26, 1996, Athens, Greece.
Two temporary pacing electrodes were positioned in the right atrium and the right ventricle. Three pacing modes were applied in a random sequence: (a) atrial pacing, (b) atrioventricular (AV) sequential pacing from the right ventricular apex and (c) AV sequential pacing from the proximal right ventricular septum. During septal pacing, the electrode was placed high in the outflow tract and was pulled back until the tip pointed in a lateral direction on a posteroanterior fluoroscopic projection, as previously described [6] (Fig. 1). The position was confirmed in the right and left anterior oblique projections. Based on previous reports [4], each pacing mode lasted for 5 min, with 5 min intervals between each mode. Pacing rate was 15 beats per minute above the resting sinus rate. To prevent fusion beats, AV-delay was set at 60% of the PR interval during sinus rhythm. The duration of the QRS complex was measured from hard copy recordings (at paper speed 100 mm / sec), using hand-held calipers. Coronary blood flow velocity was recorded during the last minute of each pacing sequence, using a steerable Doppler guidewire (FloWire, Cardiometrics,
0167-5273 / 98 / $19.00 1998 Elsevier Science Ireland Ltd. All rights reserved. PII: S0167-5273( 98 )00215-0
T.M. Kolettis et al. / International Journal of Cardiology 66 (1998) 203 – 205
204
Inc., Mountain View, CA, USA), positioned in the proximal part of the left anterior descending coronary artery, as previously described [7]. Average peak velocity and diastolic to systolic velocity ratio were measured. To prevent variations in coronary artery diameter, vasodilation was induced by intracoronary injection of 250 mg nitroglycerin, as reported previously [8]. Arterial pressure and the ECG were continuously recorded. Comparison between variables was performed using analysis of variance for repeated measures, followed by Tukey’s HSD test. Statistical significance was defined at an alpha level of 0.05.
3. Results Seventeen patients (mean age 56610 years, 14 male) were studied. There were no procedure-related complications. Although systolic pressure was lower during apical compared to atrial pacing, mean blood pressure remained unchanged (Table 1). No significant differences were found in the average peak velocity or in diastolic to systolic velocity ratio (Table 2).
4. Discussion Fig. 1. Anteroposterior fluoroscopic view of the flow-wire at the proximal part of the left anterior descending coronary artery. One temporary electrode catheter is seen in the right atrium and one at the apex of the right ventricle (panel A) or at the high right ventricular septum (panel B).
Compared to atrial pacing, ventricular apical pacing may be associated with lower resting coronary blood flow velocity [3]. This may be secondary to the altered ventricular depolarization sequence [2,3].
Table 1 Blood pressure and QRS duration during pacing Variable SBP (mmHg) DBP (mmHg) MBP (mmHg) QRS (ms)
AAI
DDD Apex
DDD Septum
a
143613
8368
8467
10469 8666
147614
139614
F value
p value
6.9
0.0031
8468
0.10
0.37
10269
10469
1.15
0.32
15665
15165
N /A
0.014 b
AAI, Atrial pacing; DDD Apex, Atrioventricular sequential pacing from the right ventricular apex; DDD Septum, Atrioventricular sequential pacing from the proximal right ventricular septum; SBP, Systolic blood pressure; DBP, Diastolic blood pressure; MBP, Mean blood pressure; N /A, non applicable. a p,0?05 compared to AAI pacing. b post-hoc comparison p value.
T.M. Kolettis et al. / International Journal of Cardiology 66 (1998) 203 – 205
205
Table 2 Coronary blood flow velocity parameters during pacing Variable
AAI
DDD Apex
DDD Septum
F value
p value
APV DSVR
25.369.0 2.3560.83
24.569.0 2.2560.46
25.8610.5 2.0660.45
1.09 1.81
0.34 0.17
AAI, Atrial pacing; DDD Apex, Atrioventricular sequential pacing from the right ventricular apex; DDD Septum, Atrioventricular sequential pacing from the proximal right ventricular septum; APV, Average peak velocity; DSVR, Diastolic to systolic velocity ratio.
Animal data have suggested significant variations in coronary blood flow velocities (predominantly in the left anterior descending artery) during different degrees of pacing-induced asynchrony [4]. In the present study, we report constant resting coronary blood flow velocity during short-term pacing from two ventricular sites, previously [5] shown to result in varying degrees of asynchrony. This finding may contribute to the on-going clinical evaluation of the optimal ventricular pacing site. Possible limitations of our study are the following: (a) We examined only resting coronary blood flow and not coronary blood flow during maximal hyperemia. Nonetheless, maximal hyperemia may abolish potential variations in resting coronary blood flow [3,4]. (b) Although we measured velocity and not actual flow, this limitation was largely overcome by nitroglycerin-induced vasodilation [8]. In summary, short-term apical and proximal septal pacing are associated with comparable resting blood flow in the left anterior descending coronary artery.
Acknowledgements The authors are indebted to Mrs. Panayiota
Panagaki, RN, and Mrs. Efthalia Tzanalaridou, BSc, for their valuable contribution to this work.
References [1] Aoyagi T, Iizuka M, Takahashi T, et al. Wall motion asynchrony prolongs time constant of left ventricular relaxation. Am J Physiol 1989;257:H883–90. [2] Ono S, Nohara R, Kambara H, Okuda K, Kawai C. Regional myocardial perfusion and glucose metabolism in experimental left bundle branch block. Circulation 1992;85:1125–31. [3] Kolettis TM, Kremastinos DT, Kyriakides ZS, Tsirakos A, Toutouzas PK. Effects of atrial, ventricular and atrioventricular sequential pacing on coronary flow reserve. PACE 1995;18:1628– 35. [4] Amitzur G, Manor D, Pressman A, et al. Modulation of the arterial coronary blood flow by asynchronous activation with ventricular pacing. PACE 1995;18:697–710. [5] Rosenqvist M, Bergfeldt L, Haga Y, Ryden J, Ryden L, Owall A. The effect of ventricular activation sequence on cardiac performance during pacing. PACE 1996;19:1279–86. [6] Buckingham TA. Right ventricular outflow tract pacing. PACE 1997;20:1237–42. [7] Segal J, Kern MJ, Scott NA, et al. Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty. J Am Coll Cardiol 1992;20:276–86. [8] Claeys MJ, Vrints CJ, Bosmans J, Krug B, Blockx PP, Snoeck JP. Coronary flow reserve during coronary angioplasty in patients with a recent myocardial infarction: relation to stenosis and myocardial viability. J Am Coll Cardiol 1996;28:1712–9.