Superior neurologic recovery after 15 minutes of normothermic cardiac arrest using an extracorporeal life support system for optimized blood pressure and flow.

OBJECTIVE: Sudden cardiac arrest is one of the leading causes of death. Conventional CPR techniques after cardiac arrest provide circulation with reduced and varying blood flow and pressure. We hypothesize that using pressure- and flow-controlled reperfusion of the whole body improves neurological recovery and survival after 15 min of normothermic cardiac arrest. METHODS: Pigs were randomized in two experimental groups and exposed to 15 min of ventricular fibrillation (VF). After this period, the animals in the control group received conventional CPR with open chest compression (n=6), while circulation in the treatment group (n=6) was established with an extracorporeal life support system (ECLS) to control blood pressure and flow. Follow-up included the assessment of neurological recovery and magnetic resonance imaging (MRI) for up to 7 days. RESULTS: Five of the six animals in the control group died, one animal was resuscitated successfully. In the treatment group, 1/6 could not be separated from ECLS. Five out of the six pigs survived and were transferred to the animal facility. One animal was unable to walk and had to be sacrificed 30 hours after ECLS. The remaining 4 animals of the treatment group and the surviving pig from the control group showed complete neurological recovery. Brain MRI revealed no pathological changes. CONCLUSION: We were able to demonstrate a significant improvement in survival after 15 minutes of normothermic cardiac arrest. These results support our hypothesis that using an ECLS for pressure- and flow-controlled circulation after circulatory arrest is superior to conventional CPR.

Continuous antegrade blood cardioplegia: cold vs. tepid.

BACKGROUND: Continuous antegrade blood cardioplegia (CABCP) is used at different temperatures. We investigated the consequences of CABCP at 6 degrees C (COLD) vs. 28 degrees C (TEPID). METHODS: Anesthetized open-chest pigs (25 +/- 2 kg) were placed on cardiopulmonary bypass (CPB). The hearts were arrested for 30 min by 6 degrees C cold or 28 degrees C tepid CABCP (n = 8 each). After an initial 3 min antegrade application of high potassium (20 mEq) cold (6 degrees C) blood cardioplegia, the hearts were arrested for a subsequent 27 min by normokalemic blood delivered antegrade at either 6 degrees C or 28 degrees C. After this, the hearts underwent perfusion with warm systemic blood for an additional 30 min on CPB. Biochemical cardiac data (MVO2 [ml/min/100 g], release of creatine kinase [CK U/min/100 g] and lactate [mg/min/100 g]) were measured during CPB. Total tissue water content (%) and left ventricular stroke work index (SWI g x m/kg) were determined 30 min after discontinuation of CPB and compared to pre-CPB controls. RESULTS: Cold CABCP kept all hearts continuously arrested. The COLD hearts showed no biochemical or functional disturbance. The TEPID hearts intermittently fibrillated and required additional high potassium BCP shots. The TEPID hearts showed a marked CK leakage (2.6 +/- 0.4 vs. 0.7 +/- 0.4), lactate production (4.0 +/- 1.6 vs. extraction from the COLD group) despite the non-ischemic protocol, an impaired initial oxygen consumption (4.2 +/- 1.3 vs. 7.1 +/- 1.6) at the end of cardiac arrest, the formation of myocardial edema (79.5 +/- 1.0 vs. 77.0 +/- 0.8), and a depressed recovery of SWI (0.69 +/- 0.15 degrees vs. 1.41 +/- 0.13). *p < 0.05 for comparison of TEPID vs. COLD hearts using Student's t-test for unpaired data; degrees p < 0.05 for intergroup-comparison of TEPID vs. COLD vs. controls using ANOVA adjusted for repeated measures. CONCLUSIONS: Uninterrupted cardioplegia can be safely performed with cold normokalemic CABCP. In contrast, tepid normokalemic CABCP leads to fibrillation, jeopardizes the heart, and should be avoided.UND

Cold continuous antegrade blood cardioplegia: high versus low hematocrit.

OBJECTIVE: Cold continuous antegrade blood cardioplegia (CCABCP) is used with different hematocrit values. We investigated the consequences of CCABCP with low hematocrit (LH: 20-25%) versus high hematocrit (HH: 40-45%). METHODS: Anesthetized open chest pigs (25 kg) were placed on cardiopulmonary bypass (CPB). The hearts were arrested for 30 min by 6 degrees C CCABCP with either LH or HH (n=8, each): After an initial 3 min application of high potassium (20 mEq) BCP the hearts were arrested for subsequent 27 min by normokalemic 6 degrees C cold blood delivered continuously antegradely. Thereafter the hearts underwent perfusion with warm systemic blood for an additional 30 min on CPB. Biochemical cardiac data (MVO(2) (ml min(-1)100 g(-1)), release of creatine kinase (CK; units min(-1)100 g(-1))) and lactate (mg min(-1)100 g(-1))) and the coronary vascular resistance index (CVRI (mmHg ml(-1)ming)) were measured during CPB. Total tissue water content (%) and left and right ventricular stroke work indices (LV-and RV-SWI (g m kg(-1))) were assessed 30 min after discontinuation of CPB and compared to pre-CPB controls. RESULTS: The hearts of the LH group had no biochemical or functional disturbance. The HH group showed marked CK leakage (0.6+/-0.2* vs. 0.1+/-0.1, *P<0.05 for comparison of LH vs. HH with Student's t-test for unpaired data), impaired initial oxygen consumption (4+/-1* vs. 7+/-1) after cardiac arrest, an increased CVRI (82+/-12* vs. 50+/-8), the formation of myocardial edema (81.0+/-1.3* vs. 77.5+/-1.2), and poor functional recovery (LVSWI 0.2+/-0.1* vs. 1.0+/-0.1; RVSWI 0.1+/-0.1* vs. 0.5+/-0.1). The absence of lactate production in both groups was in accord with the non-ischemic protocol. CONCLUSIONS: CCABCP with a low hematocrit of 20-25% is cardioprotective. In contrast, CCABCP with a high hematocrit of 40-45% jeopardizes the heart despite avoiding ischemic periods, and should be avoided.

Overview: procedure versus protection: an impossible separation.

This overview focuses upon the fundamental cohesion between myocardial protection and mechanical repair for surgical success. Currently, our attention is directed toward the natural evolution of more complex surgical methods, while there is slower rise in interest in advanced methods of protection. The absence of manuscripts on myocardial protection in major meetings suggests that the concept of protection has been solved, even though there remain reports of use of intraaortic balloon and mechanical devices that appear when protection is inadequate. This Seminar volume will introduce a series of articles about risk patients for whom evolving methods of protection are used. We will point out frontiers of protection that should develop together with advances in technical surgical approaches so that these two essential components that insure the safe conduct of cardiac operations can grow together.

The role of integrated myocardial management in reoperative coronary surgery.

This article identifies the effect of integrated myocardial protection on outcomes after first-time repeat coronary artery bypass grafting (CABG). A consecutive series of 124 repeat CABG procedures were performed between January 1996 and December 1999 with single aortic cross-clamping for all anastomoses and integrated myocardial protection. This included ischemia for heart dissection and distal grafting, and perfusion throughout the remainder of aortic clamping (including warm/cold, substrate/nonsubstrate-enhanced blood cardioplegia, delivered antegrade/retrograde, continuously/intermittently). Mean patient age was 67 +/ - 10 years (median 68) with 61% in New York Heart Association class IV and 23% in class III. Mean ejection fraction (EF) was 45 +/- 10.6% with EF 40% or less in 33% of patients and 30% or less in 20%. An average of 2.5 +/- 0.9 grafts were constructed. Cross-clamp times averaged 72 +/- 22 min and cardiopulmonary bypass time averaged 91 +/- 27 min. The average time from release of cross-clamp it disconnection from cardiopulmonary bypass (CPB) was 10 min. Median postoperative hospital stay was 6 days. hospital mortality was 2.4%, intra-aortic balloon pump (IABP) use 3.2%, stroke 0.8%, atrial fibrillation 11%, and reexploration for bleeding 2.4%. Integrated myocardial protection with blood cardioplegia is safe during reoperative coronary surgery. It allows rapid separation from CPB, limited IABP use, and low morbidity and mortality.

The beating open heart for rebuilding ventricular geometry during surgical anterior restoration.

Heart failure is an increasing problem because of successful therapies in younger age groups and an overall increase in age in the general population. Ischemic cardiomyopathy secondary to myocardial infarction is the most prevalent entity among the several causes for cardiac failure. Among the surgical options for these patients, neither transplantation nor current ventricular assist devices are able to treat a sufficient number of patients. Ventricular restoration, however, may evolve as a surgical option to treat myocardial failure secondary to postinfarction ventricular dilatation. This procedure must be undertaken in high-risk coronary artery bypass graft (CABG) patients in heart failure. We describe the techniques for both the conventional procedure (CABG +/- mitral valve [MV] repair) using cardioplegic methods, and the beating open heart for surgical anterior ventricular restoration (SAVR) for dyskinetic and akinetic areas in ischemic cardiomyopathies. This combined approach allows safe restoration of the ventricular geometry with minimal use of mechanical support (ie, intra-aortic balloon pump [IABP]) in 195 consecutive patients undergoing this procedure by members of an international team called the RESTORE group.

Cardioplegia solutions--unproven herbal approach versus tested scientific study.

Cardioplegic solutions are used throughout the world, but must undergo careful testing before their clinical application. This study points out the importance of recognizing the hemodynamic changes produced by tested solutions so that appropriate decisions can be made in selecting crystalloid or blood solutions. Examples are provided, in which arbitrary changes made by the well-intentioned surgeon can produce damage through unanticipated alterations that are introduced without prior testing, and then used clinically. Recognition of the advantages and disadvantages of each solution is the underpinning of selection for clinical use so that unanticipated misadventures do not occur. Furthermore, the importance of making solutions in pharmacies with good manufacturing practices can avoid causing problems that would otherwise be prevented. Fundamentally, cardioplegic solutions are direct cardiac medications that must be tested as other drugs are so that unforeseen problems are avoided.

Surgical anterior ventricular endocardial restoration (SAVER) in the dilated remodeled ventricle after anterior myocardial infarction. RESTORE group. Reconstructive Endoventricular Surgery, returning Torsion Original Radius Elliptical Shape to the LV.

OBJECTIVES: The goal of this study was to evaluate the safety and efficacy of surgical anterior ventricular endocardial restoration (SAVER). The procedure excludes noncontracting segments in the dilated remodeled ventricle after anterior myocardial infarction. BACKGROUND: Anterior infarction leads to change in ventricular shape and volume. In the absence of reperfusion, dyskinesia develops. Reperfusion by thrombolysis or angioplasty leads to akinesia. Both lead to congestive heart failure by dysfunction of the remote muscle. The akinetic heart rarely undergoes surgical repair. METHODS: A new international group of cardiologists and surgeons from 11 centers (RESTORE group) investigated the role of SAVER in patients after anterior myocardial infarction. From January 1998 to July 1999, 439 patients underwent operation and were followed for 18 months. Early outcomes of the procedure and risk factors were investigated. RESULTS: Concomitant procedure included coronary artery bypass grafting in 89%, mitral valve (MV) repair in 22% and MV replacement in 4%. Hospital mortality was 6.6%, and few patients required mechanical support devices such as intraaortic balloon counterpulsation (7.7%), left ventricular assist device (0.5%) or extracorporeal membrane oxygenation (1.3%). Postoperatively, ejection fraction increased from 29 +/- 10.4 to 39 +/- 12.4%, and left ventricular end systolic volume index decreased from 109 +/- 71 to 69 +/- 42 ml/m2 (p < 0.005). At 18 months, survival was 89.2%. Time related survival at 18 months was 84% in the overall group and 88% among the 421 patients who had coronary artery bypass grafting or MV repair. Freedom from readmission to hospital for congestive heart failure at 18 months was 85%. Risk factors for death at any time after the operation included older age, MV replacement and lower postoperative ejection fraction. CONCLUSIONS: Surgical anterior ventricular endocardial restoration is a safe and effective operation in the treatment of the remodeled dilated anterior ventricle after anterior myocardial infarction.

The structure and function of the helical heart and its buttress wrapping. I. The normal macroscopic structure of the heart.

The Gordian knot of anatomy has been the architectural arrangement of ventricular muscle mass, which may have finally become understood. The description of Francisco Torrent-Guasp's model of the helical heart is presented, which includes the cardiac structures that produce 2 simple loops that start at the pulmonary artery and end in the aorta. An unscrolled ventricular band is shown, achieved by blunt dissection that extends between the points of origin of the right ventricle, at the pulmonary artery root, to termination at the aortic root, in the left ventricle. These components include a spiral horizontal basal loop that surrounds the right and left ventricular cavities, and changes direction to cause a second spiral, produced by almost vertically oriented fibers, giving rise to the helical configuration of the ventricular myocardial band. These anatomic structures are successively activated, as with a peristaltic wave, starting at the right ventricle (just below the pulmonary artery) and progressing toward the aorta to produce a sequence of narrowing, caused by the basal loop contraction, shortening (related predominantly to the descendant segment contraction), lengthening (produced by the ascendant segment contraction), and widening, as a consequence of several factors that act during ventricular myocardium relaxation. These sequences control the ventricular events responsible for ejection to empty and suction to fill. These mechanical interactions of structure and function are defined in relation to chronologic location of the successive cardiac functional events in the aortic, left ventricular, and left atrial recordings.

The structure and function of the helical heart and its buttress wrapping. II. Interface between unfolded myocardial band and evolution of primitive heart.

The unfolded myocardial band containing a central fold, extending between the pulmonary artery and aorta, has been used to explain the intact or wrapped cardiac structure, composed of a basal and apical loop forming a buttress and helix, connected to the outflow vessels of both ventricles. The interface between this simple structure, and embryologic development of the primitive heart evolving from a singular tube, into a dual pumping chamber with separate left and right sides, must be explained. The objective is to suggest that a simple and integrated triple figure-eight spiral band, with three S-shaped helixes and their apices may correlate the conventional embryologic development of the primitive heart (bulbus cordis, ventricle, and arterial outflow vessels), with the three stages of spatial orientation of the myocardial band (basal and apical loops), which extends between dual ventricular outflow vessels, in the sequence defined by the unwrapped myocardial band.

The structure and function of the helical heart and its buttress wrapping. III. The electric spiral of the heart: The hypothesis of the anisotropic conducting matrix.

The study of the dissemination of the electric impulse throughout the ventricular myocardium, which gave rise to the current theories, was performed without taking into consideration the complex architecture of the cardiac muscle elucidated by more recent researchers. We propose a novel hypothesis based on the special macroscopic structure of the heart, the anisotropic electric and mechanical behavior of the myocardium, the characteristics of the intercellular matrix and its very special collagen scaffolding, chemical composition, and biochemistry. The unique properties of the intercellular matrix would make it especially suited to function, in conjunction with the specialized conducting system (His-Purkinje system), as an efficient anisotropic conductor for the spread of electric activation in the heart, and to allow an optimal sequence of excitation-contraction coupling that results in the coordination of effective myocardial contraction in birds and mammals of the most varied known heart rates.

The structure and function of the helical heart and its buttress wrapping. IV. Concepts of dynamic function from the normal macroscopic helical structure.

Torrent-Guasp's model of the helical heart is presented, which includes the cardiac muscular structures that produce 2 simple loops and that start at the pulmonary artery and end in the aorta. These components include a horizontal basal loop that surrounds the right and left ventricles, changes direction through a spiral fold in the ventricular band to cause a ventricular helix produced by now obliquely oriented fibers, forming a descending and ascending segment of the apical loop with an apical vortex. These anatomic concepts are successively activated to produce a sequence of narrowing by the basal loop, shortening by the descending segment, lengthening by the ascending segment, and widening in the cardiac cycle that causes ventricular ejection to empty and suction to fill. The factors responsible for internal torsional movements for cardiac output and suction are defined, together with mechanisms responsible for electromechanical activity produced during sequential changes in contraction and relaxation properties. These interactions of mechanical structure and function are defined in relation to pressure-related cardiac events observed from aortic, left ventricular, and left atrial recordings.

The structure and function of the helical heart and its buttress wrapping. V. Anatomic and physiologic considerations in the healthy and failing heart.

A macroscopic structure of an elliptic heart, formed by the helix provided by the apical loop, is defined and related, initially, to normal function. To define the sequence of normal progressive muscular activity, cardiac pressure, magnetic resonance imaging (MRI), and multiple gated acquisition (MUGA) records are reviewed. This novel format of structure for the helical heart is then compared with historic studies of ventricular structure. New concepts will show how the basal loops cause initial isovolumetric contraction, together with factors responsible for contractile ventricular lengthening responsible for filling by suction. The interaction of these muscular-functional changes are correlated to basic studies of electrophysiology (excitation-contraction) to set the stage for alterations produced by changing the helical apex to a sphere during congestive heart failure. Macroscopic changes in heart failure, which convert the ellipse to a globe, are defined as the underpinning of dilated cardiomyopathy. It is our hypothesis that the commonality of this spheric left ventricular substrate becomes responsible for ischemic, idiopathic, and dilated ventricular cardiomyopathy.

The structure and function of the helical heart and its buttress wrapping. VI. Geometric concepts of heart failure and use for structural correction.

The macroscopic basis for congestive heart failure is defined as conversion of a helical heart, whereby the apical loop fiber angle orientation that produces a 60% ejection fraction becomes more transverse to develop a spheric configuration. The geometric consequence is flattening of the apical loop architecture, so that the 15% shortening can produce only 30% ejection fraction. The fundamental shape change is alteration of normal relationships between the transverse basal loop and oblique apical loop, to make the apical loop become more basal through more transverse fiber orientation. These fundamental architectural changes are then used to evolve new procedures that restore a more normal, helical, ventricular architecture in ischemic and dilated cardiomyopathy. Direct intraoperative ventricular methods underlie surgical ventricular restoration or endoventricular surgical patch plasty procedures, the Batista procedure, and Pacopexy. These intraventricular objectives are then compared with external approaches without ventriculotomy (ie, reimplantation of cells, pericardial sleeve (acorn), surface radiofrequency ablation, and the myocor approaches). A survey of current direct ventricular clinical results that improve the underlying nondamaged muscle (ie, remote segment) is defined, and related to timing of procedures directed at rebuilding more normal ventricular shape before irreversible collagen and fibrosis develop. The overall intent is to convert the spheric heart into an elliptic configuration. Novel concepts are introduced to suggest an internal ventricular patch can be used as an intercavitary curtain, through covering nonscarred septal muscle (ie, normal but distended) to amplify left ventricular function through producing a more helical structure.

The structure and function of the helical heart and its buttress wrapping. VII. Critical importance of septum for right ventricular function.

The macroscopic structure of the right ventricle includes a transverse basal loop for the free wall, and oblique septal components, originating from the descending and ascending segments of the apical loop. Data is presented that determines why right ventricular function is related principally to intraventricular septal function, and why right ventricular failure is magnified by septal stunning caused by poor myocardial protection. The background of this architectural/functional change can explain normal right ventricular function, the relationship of right ventricular performance to pulmonary vascular resistance, experimental studies that characterize right ventricular performance after architectural free wall ablation, right ventricular disconnection, right coronary occlusion, and free wall replacement. These basic science studies are related to perioperative right ventricular performance, involving methods of myocardial protection, protamine reaction, right coronary occlusion and reperfusion, right ventricular dyskinesia, chronic aortic and mitral valve replacement (MVR) replacement, congenital heart disease, right and left ventricular assist devices (LVADs), and transplantation. The predominant focus is related to the septum and how it can be evaluated perioperatively. Septal evaluation by echocardiogram should become an essential feature during intraoperative management.

Seeing congestive heart failure with the eyes of the mind: a surgical view.

Our normal approach is to recognize pathology and deal with what we see. This article shows that surgical actions in patients with congestive heart failure (CHF) are based on secondary changes in apparently normal looking structures that must be altered to restore normal function. These interventions follow the process of opening the normal pericardium to deal with the abnormal heart. Recognition of conceptual changes in structures without obvious pathology will lead to our incising the normal epicardium to deal with the scarred underlying muscle, narrowing the normal annulus to alter tethering of the lengthened papillary muscle chord connections, imbricating dilated normal myocardium between papillary muscle heads to narrow secondary widening, and rebuilding the dilated spheric ventricle to restore a normal elliptic contour. The overall objective is make our mental concepts guide surgical activities, and thus go beyond evident pathology in our corrective efforts. Our intent is to escape the boundary of the visible disease, and aim restoration toward the boundary of normality.