ATS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Richard Gitter
G. Kimble Jett
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gitter, R.
Right arrow Articles by Jett, G. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gitter, R.
Right arrow Articles by Jett, G. K.

Ann Thorac Surg 1998;65:365-370
© 1998 The Society of Thoracic Surgeons

Original Articles: Cardiovascular

Influence of Ascending Versus Descending Balloon Counterpulsation on Bypass Graft Blood Flow

Richard Gitter, MD, Chris M. Cate, MD, Kenneth Smart, MD, G. Kimble Jett, MD

Departments of Surgery and Cardiothoracic Surgery, Baylor University Medical Center, Dallas, Texas, USA

Dr Jett, Circulatory Assistance, Baylor University Medical Center, 9330 Poppy Dr, #506, Dallas, TX 75218.

Presented at the Forty-Third Annual Meeting of the Southern Thoracic Surgical Association, Cancun, Mexico, Nov 7–9, 1996.


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 References
 
Background. Mechanical circulatory assistance is frequently needed in postcardiotomy patients to support the failing heart. A balloon catheter called SupraCor (ABIOMED Cardiovascular, Inc, Danvers, MA) has been developed and is similar to the existing intraaortic balloon pump with the exception of placement in the ascending versus the descending thoracic aorta. This investigation compared the effects of SupraCor versus standard intraaortic balloon pump on internal mammary artery and venous conduit bypass graft blood flow.

Methods. Porcine total heart bypass was used to anastomose a jugular vein from the ascending aorta to a subsequently ligated left anterior descending coronary artery. The left internal mammary artery was then anastomosed to the jugular vein so each conduit perfused the same coronary vascular bed. An additional right heart bypass preparation allowed precise control of cardiac output and blood pressure, which were maintained constant throughout mechanical circulatory assistance. Electromagnetic flow probes measured flow through each bypass graft and the other conduit was atraumatically occluded.

Results. The SupraCor caused a significant increase in both internal mammary artery (+70% from 35 ± mL/min to 56 ± 9 mL/min; p = 0.04) and venous bypass graft blood flow (+49% from 66 ± 12 mL/min to 95 ± 15 mL/min; p = 0.02) when compared with controls. The intraaortic balloon pump failed to alter internal mammary artery or venous bypass graft flow.

Conclusions. The results demonstrate that counterpulsation with an ascending aortic balloon significantly increases coronary bypass graft flow in both internal mammary artery and venous conduits. In contrast, counterpulsation with a descending aortic balloon did not alter coronary bypass graft flow.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 References
 
Mechanical circulatory assistance is frequently needed to support the failing heart. Postcardiotomy ventricular dysfunction is increasing as the patient population referred for surgical treatment increases in age and severity of preoperative left ventricular dysfunction [1]. The use of mechanical devices in postcardiotomy patients has doubled from 6.4% in 1986 to 12.7% in 1990 [2] [3].

The intraaortic balloon pump (IABP) is a pneumatic device that inflates and deflates a balloon placed in the descending thoracic aorta. Balloon inflation is counter-synchronized with the heart. A support device called the SupraCor (ABIOMED Cardiovascular Inc, Danvers, MA) has been developed to aid patients with severe ventricular dysfunction. This device is similar to the existing IABP with the exception of the shape of the balloon and the placement in the aorta. The SupraCor is oval and placed in the ascending aorta, closer to the heart than the IABP, and therefore may provide improved benefit to the heart by further decreasing afterload and increasing coronary blood flow [4] [5]. Our study examined the influence of ascending versus descending aortic balloon counterpulsation on coronary bypass graft flow in an experimental model holding all other variables constant.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 References
 
Adult pigs were used for these studies. The aorta of pigs resembles the human aorta anatomically and therefore, provides an adequate experimental model. All animals received humane care in compliance with the "Principles of Laboratory Animal Care" set forth by the National Society for Medical Research and the "Guide for the Care and Use of Laboratory Animals" prepared by the Institute of Laboratory Animal Resources and published by the National Institutes of Health (NIH publication 85-23, revised 1985).

The pigs were anesthetized with 2% isoflurane. A cuffed endotracheal tube was inserted and ventilation was provided with a volume ventilator. A median sternotomy was performed and the left internal mammary artery (IMA) harvested as a pedicle graft. A jugular vein was harvested from the neck. The pigs were systemically heparinized and a two-stage single lumen venous cannula was inserted into the right atrium and an aortic cannula was inserted retrograde through the right innominate artery such that the tip resided in the ascending aorta. A Sarns roller pump with a bubble oxygenator was used for heart-lung bypass. The animals were kept normothermic throughout the study. After aortic cross-clamping and antegrade cardioplegic infusion, the vein graft was anastomosed to the left anterior descending coronary artery and then the proximal ascending aorta. The cross-clamp was then released and the IMA was anastomosed to the very distal aspect of the vein graft while the heart recovered. The left anterior descending coronary artery was then ligated proximal to the venous graft and the bypass conduits were allowed to flow freely. The left anterior descending coronary artery was ligated so that the sole perfusion of the distal left anterior descending coronary bed was provided by the bypass grafts [6]. Last, the right ventricular outflow tract was cannulated with the cannula extending through the pulmonic valve to provide right heart bypass. This allowed for maintenance of a constant cardiac output of 50 mL · kg-1 · min-1 throughout each study. This level of flow approximates the swine’s native cardiac output. When higher flows were used (100 mL · kg-1 · min-1), pulmonary edema resulted.

After completion of the bypass preparation, a femoral artery cut down was done to cannulate the artery with a 12.5F balloon introducer sheath. The same introducer was used for both intraaortic balloons. The SupraCor is an oval balloon designed to reside in the ascending aorta proximal to the innominate artery but distal to the aortic root. Its distal catheter is curved to mimic the geometry of the aortic arch (Fig 1Fig 2). The IABP is a cylindric balloon also advanced from the femoral artery and is designed for its tip to reside just distal to the left subclavian artery (Fig 1Fig 3). Both balloons were synchronized to the electrocardiogram to counterpulsate with the heart and were inflated in a 1:1 ratio. Both the SupraCor and the IABP were inflated with 40 mL of helium gas provided by a Datascope 90 console (Datascope Corp, Monvale, NJ).



View larger version (94K):
[in this window]
[in a new window]
  		The oval ascending aortic balloon is shown on the left and the standard cylindric descending aortic balloon is shown on the right.

 


View larger version (95K):
[in this window]
[in a new window]
  		SupraCor balloon is shown in position in the ascending aorta (IMA = internal mammary artery; LAD = left anterior descending coronary artery; SVG = saphenous vein graft.)

 


View larger version (94K):
[in this window]
[in a new window]
  		The intraaortic balloon pump is shown positioned in the descending thoracic aorta (IMA = internal mammary artery; LAD = left anterior descending coronary artery; SVG = saphenous vein graft.)

 
Measurements
Aortic pressures were measured in the ascending aorta proximal to the ascending aortic balloon using a Micro-Tip pressure transducer (Millar Instruments, Inc, Houston, TX) inserted through the ventricular apex and advanced into the aortic root. Left ventricular and atrial pressures were measured with a Micro-Tip catheter inserted through the ventricular apex and a fluid-filled catheter inserted through the right superior pulmonary vein, respectively. All pressures were recorded on a monitor (Marquette Electronics, Milwaukee, WI).

The IMA and venous graft flow rates were measured with an electromagnetic flow probe (Carolina Medical Electronics, King, NC) collared around the proximal aspects of each bypass graft. Previous studies have demonstrated the probe accuracy, after automatic calibration, within 1 to 2 mL/min [7].

Cardiac output was kept constant at 50 mL · kg-1 · min-1 by right heart bypass with the infusion of blood into the pulmonary artery. Blood pressure was maintained constant by the infusion or extraction of intravascular volume through a separate arterial cannula. Heart rate remained constant throughout the experiment.

Myocardial oxygen consumption was estimated by the calculation of the systolic pressure–time index. The ratio of the diastolic to the systolic pressure–time index was used to evaluate myocardial oxygen supply and demand [8]. The systolic and diastolic pressure–time index were obtained from the measurements of the area under the systolic and diastolic portion of the aortic pressure curve, respectively.

Experimental Protocol
Six adult pigs were studied. The average weight of the animals was 64.5 kg. Three pigs were female and 3 were male.

Control blood flow rates were measured in each bypass graft before and after balloon counterpulsation and the other conduit was atraumatically occluded. Hemodynamic and bypass graft flow rates were recorded 15 minutes after institution of balloon pumping. The balloons were studied in random order. The location of each balloon was verified by digital palpation. The SupraCor was inserted just distal to the aortic root but proximal to the brachial cephalic artery, and the standard IABP was placed just distal to the left subclavian artery.

Statistical Analysis
The hemodynamic and blood flow parameters of each mechanical intervention were compared with control levels. The significance of hemodynamic changes and percent change from control flow were tested using a two-tailed, paired Student’s t test. Probability values less than 0.05 were considered statistically significant.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 References
 
SupraCor ascending arch balloon caused a significant increase in IMA graft flow from 35 ± 8 mL/min to 56 ± 9 mL/min. The IABP failed to alter IMA bypass flow with a mean change from 47 ± 12 mL/min to 49 ± 9 mL/min (Table 1). Venous bypass graft flow was also significantly increased by the SupraCor from 66 ± 12 mL/min to 95 ± 15 mL/min, whereas the IABP failed to alter venous conduit flow (Table 1). Ascending aortic balloon counterpulsation resulted in a 70% ± 29% increase in IMA blood flow and a 49% ± 15% increase in venous bypass blood flow when compared with controls. The standard balloon had no significant effect on bypass graft blood flow.


View this table:
[in this window]
[in a new window]
  		Blood Flow (mL/min)1

 
As previously discussed, cardiac output was maintained constant by the right heart bypass preparation. Neither device altered heart rate, left arterial pressure, left ventricular systolic pressure, or left ventricular end-diastolic pressure. Both systolic and mean pressures were maintained constant throughout the experiments (Table 2). Diastolic augmentation was evidenced with both balloons by a significantly increased peak diastolic pressure (Table 2). The IABP and the SupraCor both significantly decreased diastolic pressure measured at the aortic root at the end of diastole (presystolic dip), although the IABP had a more pronounced effect (Table 2).


View this table:
[in this window]
[in a new window]
  		Hemodynamic Variables1

 
The variables associated with myocardial work and perfusion are demonstrated in Table 3. Mechanical assistance with both devices decreased systolic pressure–time index while maintaining the diastolic pressure–time index. The ratio of diastolic to systolic pressure–time index, which is an index of myocardial oxygen supply versus demand, was increased more with the SupraCor than the IABP. However, none of these changes reached statistical significance.


View this table:
[in this window]
[in a new window]
  		Myocardial Work/Perfusion1

 

   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
References
 
Intraaortic balloon pumping has been in widespread clinical practice for hemodynamic support since it was first reported in 1968 [4] [9] [10]. It is most commonly used for postcardiotomy low output syndrome with approximately 4% of all such patients requiring postoperative support [11]. The IABP has also recently been shown to be effective in maintaining vessel patency following thrombolysis after acute myocardial infarction or angioplasty [12] [13], presumably attributable to improved diastolic perfusion with counterpulsation.

The purported effects of intraaortic counterpulsation are decreased myocardial oxygen demand through afterload reduction and increased coronary perfusion through diastolic augmentation. Current literature supports a decrease in afterload and therefore, a reduction in myocardial oxygen demand, but the data on coronary or possibly collateral blood flow enhancement are inconsistent [3] [11] [15] [16] [17] [18] [19]. Furthermore, the counterpulsation effects on isolated coronary bypass conduit flow has received little attention. One study demonstrated an increase in saphenous vein graft flow with the intraaortic balloon, but the mean aortic pressure also significantly increased with counterpulsation [20]. Recent work with the standard IABP has demonstrated no increase in coronary inflow to the myocardium with the IABP in the presence of severe coronary artery stenosis. The major benefit of the standard IABP appears to be achieved by reducing oxygen demand by systolic unloading [21].

Under hypoxic and potentially ischemic conditions, myocardial performance is coronary or coronary bypass graft flow dependent. Previous investigators have demonstrated that under conditions of cardiogenic shock, left ventricular performance is not significantly improved with afterload reduction alone, and enhanced coronary driving pressure and therefore, perfusion is required for reversal of ventricular failure [9] [22]. Patients treated with inotropic agents in combination with vasodilators increase left ventricular work without increasing myocardial perfusion and actually decrease coronary flow by decreasing diastolic perfusion pressures [9] [17].

The pig model used in this study attempted to isolate the effect of mechanical circulatory assistance on coronary artery bypass graft flow. All hemodynamic parameters were held constant. Graft flow, however, is dependent not only on the effect of circulatory assistance on the conduit, but also on the effect on the regional coronary vasculature. In a sense this model is not a clinical analogue as it did not induce heart failure. Most mechanical support is instituted for hemodynamic support, although recent studies have focused on coronary support [12] [13]. We attempted to isolate the effect of balloon counterpulsation on coronary bypass graft flow by holding the hemodynamic variables constant.

Our study demonstrates that counterpulsation with the ascending aortic balloon significantly increased coronary bypass blood flow in both the IMA (+70%) and venous conduits (+49%), while successfully reducing afterload. In contrast, counterpulsation with the standard descending aortic balloon did not alter coronary bypass flow in either the venous or arterial conduits. The failure to alter conduit flow with counterpulsation in the descending aorta may be attributable to a greater decrease in end-diastolic blood pressure. It is interesting that IMA flow was increased more than vein graft flow.

This study also demonstrated improved global myocardial oxygen supply and demand balance with both devices. The diastolic pressure–time index was constant with counterpulsation despite a reduction in the systolic pressure–time index. This suggests a marked reduction in myocardial oxygen demand/consumption and maintenance of coronary perfusion and enhanced endocardial viability with both balloons. This enhancement was more marked with the SupraCor, perhaps because of or resulting from improved coronary bypass graft flow. A recent study using extraaortic balloon counterpulsation of the ascending aorta demonstrated similar results [23].

The geometric advantage offered by the ascending balloon has been described above. Its position within the ascending aorta may be responsible for its improved effects by causing retrograde propulsion of blood against a closed aortic valve, thus improving coronary blood flow and resulting in greater afterload reduction. Early work using a dual chamber aortic root balloon also demonstrated superior results [10]. The conventional IABP uses a longer proximal length of aorta, with its respective branches, and its counterpulsation wave is thus attenuated. However, the location of a balloon in the ascending aorta may increase the risk of cerebral emboli.

The results demonstrate that counterpulsation with an ascending aortic balloon significantly increases coronary bypass graft flow in both the IMA and venous conduits. In contrast, counterpulsation with the descending aortic balloon did not alter coronary bypass graft flow. Circulatory assistance with an ascending aortic balloon may benefit patients after coronary artery bypass grafting, especially if an IMA has been used. The safety of counterpulsation with an ascending aortic balloon, however, will await the results of the clinical trials in progress [14].


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 References
 

  1. Naunheim KS, Fiore AC, Wadley JJ, et al. The changing mortality of myocardial revascularization: coronary bypass and angioplasty. Ann Thorac Surg 1988;46:666-674.[Abstract]
  2. Ohman EM, George BS, White CJ, et al. Use of aortic counterpulsation to improve sustained coronary artery patency during acute myocardial infarction: results of randomized trial. Circ 1994;90:792-799.[Abstract/Free Full Text]
  3. Bolooki H Current status of circulatory support with intraaortic balloon pump. Cardiol Clin 1985;3:123-133.[Medline]
  4. Kishi K, Ota Y, Hiratsuka H, et al. Mechanical assistance of coronary circulation in the ischemic heart with a newly devised technique. Ann Thorac Surg 1970;9:419-430.[Medline]
  5. Chyong Y, Miura I, Ramez B, et al. Aortic root balloon pumping (ARBP): experimental study and theoretical rationale. Jpn Heart J 1971;12:263-274.[Medline]
  6. Flemma RJ, Singh HM, Tector AJ, et al. Comparative hemodynamic properties of vein and mammary artery in coronary bypass operations. Ann Thorac Surg 1973;20:619-627.
  7. DiNardo JA, Bert A, Schwartz MJ, et al. Effects of vasoactive drugs on flows through left internal mammary and saphenous vein grafts in man. J Thorac Cardiovasc Surg 1991;102:730-735.[Abstract]
  8. Buckberg GD, Fixler DE, Archie JP, Hoffman JIE Experimental subendocardial ischemia in dogs with normal coronary arteries. Circ Res 1972;30:67-81.[Abstract/Free Full Text]
  9. Bregman D, Kripke DC, Goetz RH The effects of synchronous unidirectional intraaortic balloon pumping on hemodynamics and coronary blood flow in cardiogenic shock. Trans Am Soc Artif Int Organs 1970;16:439-446.[Medline]
  10. Brown BG, Gundel WD, McGinnis GE, et al. Improved intraaortic balloon diastolic augmentation with a double balloon catheter in the ascending and the descending thoracic aorta. Ann Thorac Surg 1968;6:127-136.[Medline]
  11. McEnany MT, Kay HR, Buckley MJ, et al. Clinical experience with intraaortic balloon pump support in 728 patients. Circ 1978;58:124-132.
  12. Kono T, Morita H, Nishina T, et al. Aortic counterpulsation may improve late patency of the occluded coronary artery in patients with early failure of thrombolytic therapy. J Am Coll Cardiol 1996;28:876-881.[Abstract]
  13. Kern MJ, Aguirre F, Bach R, et al. Augmentation of coronary blood flow by intraaortic balloon pumping in patients after coronary angioplasty. Circulation 1993;87:500-511.[Abstract/Free Full Text]
  14. Katz ES, Tunick PA, Kronzon I Observations of coronary flow augmentation and balloon function during intraaortic balloon counterpulsation using transesophageal echocardiography. Am J Cardiol 1992;69:1635-1639.[Medline]
  15. Lazar JM, Ziady GM, Dummer SJ, et al. Outcome and complications of prolonged intraaortic balloon counterpulsation in cardiac patients. Am J Cardiol 1992;69:955-958.[Medline]
  16. Corral CH, Vaughn CC Intraaoratic balloon counterpulsation: An eleven year review and analysis of determinants of survival. Tex Heart Inst J 1986;13:39-44.
  17. Dormandy JA, Goetz RH, Kripke DC Hemodynamics and coronary blood flow with counterpulsation. Surg 1969;65:311-320.
  18. Flynn MS, Kern MJ, Donohue TJ, et al. Alterations of coronary collateral blood flow velocity during intraaortic balloon pumping. Am J Cardiol 1993;71:1451-1455.[Medline]
  19. Kern MJ, Aguirre F Coronary flow alternans: a unique examination of coronary physiology and influence of intraaortic balloon pumping. Am Heart J 1992;123:1369-1373.[Medline]
  20. Bregman D, Parodi EN, Edie RN, et al. Intraoperative unidirectional intra-aortic balloon pumping in the management of left ventricular power failure. J Thorac Cardiovasc Surg 1995;70:1010-1023.
  21. Kimura A, Toyota E, Songfang L, et al. Effects of intraaortic balloon pumping on septal arterial blood flow velocity waveform during severe left main coronary artery stenosis. J Am Coll Cardiol 1996;27:810-816.[Abstract]
  22. Kuhn LA, Kline HJ, Marano AJ, et al. Mechanical increase of vascular resistance in experimental myocardial infarction in shock. Circ 1966;19:1086-1096.
  23. Odaguchi H, Yozu R, Kashima I, et al. Experimental study of extraaortic balloon counterpulsation as a bridge to other mechanical assist. ASAIO J 1996;42:190-194.[Medline]



This article has been cited by other articles:


Home page
 J. Thorac. Cardiovasc. Surg.Home page
F. Onorati, G. Santarpino, A. Rubino, L. Cristodoro, C. Scalas, and A. Renzulli
Intraoperative bypass graft flow in intra-aortic balloon pump-supported patients: Differences in arterial and venous sequential conduits
J. Thorac. Cardiovasc. Surg., July 1, 2009; 138(1): 54 - 61.
[Abstract] [Full Text] [PDF]

Home page
 CirculationHome page
M. E. Legget, W. S. Peters, F. P. Milsom, J. S. Clark, T. M. West, R. L. French, and A. F. Merry
Extra-Aortic Balloon Counterpulsation: An Intraoperative Feasibility Study
Circulation, August 30, 2005; 112(9_suppl): I-26 - I-31.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
R. J.F. Baskett, W. A. Ghali, A. Maitland, and G. M. Hirsch
The intraaortic balloon pump in cardiac surgery
Ann. Thorac. Surg., October 1, 2002; 74(4): 1276 - 1287.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
B. P. Meyns, Y. Nishimura, R. Jashari, R. Racz, V. H. Leunens, and W. J. Flameng
Ascending versus descending aortic balloon: Pumping: organ and myocardial perfusion during ischemia
Ann. Thorac. Surg., October 1, 2000; 70(4): 1264 - 1269.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
H. L. Lazar
Ascending versus descending balloon counterpulsation
Ann. Thorac. Surg., August 1, 1998; 66(2): 603 - 603.
[Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Richard Gitter
G. Kimble Jett
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gitter, R.
Right arrow Articles by Jett, G. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gitter, R.
Right arrow Articles by Jett, G. K.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
J THORAC CARDIOVASC SURG ICVTS ALL CTSNet JOURNALS