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PubMed1994

Ischemic preconditioning: cardioprotection for cardiac surgery.

Traditionally, surgeons have attempted to minimize myocardial ischemic and reperfusion injury during cardiac procedures by optimizing cardioplegic solutions and modifying the conditions of reperfusion. New evidence suggests that in addition to these two strategies, surgeons may be able to induce myocardial resistance to ischemic injury, which permits immediate functional and metabolic recovery after cardiac operations. Although brief episodes of cardiac ischemia may be associated with mechanical and metabolic dysfunction ("stunning"), they have also been shown to protect against damage resulting from a subsequent prolonged ischemic episode. This phenomenon, known as ischemic preconditioning, has been extensively characterized since its original description in 1986. Recent studies in surgical models of cardioplegic arrest and reperfusion have suggested that the preconditioned, arrested heart may have an increased tolerance to prolonged ischemia and improved functional recovery after reperfusion. The development of a pharmacological agent that induces the preconditioning effect may revolutionize cardioprotection for cardiac surgery. We will review the characteristics of preconditioning and data supporting the application of this natural protective capacity to reduce ischemic damage during cardiac procedures.

Animals↗
PubMed1979

Sympathetic control of major coronary artery diameter in the dog.

The diameter of a major coronary artery, the ramus interventricularis ventralis (RIV), was measured in dogs with arrested hearts perfused by an extracorporeal circulation. The resting diastolic diameter was 1.78 +/- 0.07 mm (mean +/- SE) at a diastolic pressure of 74.2 +/- 3.4 mm Hg. Bilateral supramaximal stimulation of fibers leaving the cranial pole of the stellate ganglion decreased the diameter by 71.2 +/- 8.9 micrometer, i.e., 4.0 +/- 0.5% of the resting diameter. Stimulation of the left stellate ganglion contributed 59.8 +/- 5.7% of the maximum response; that of the right contributed 40.3 +/- 5.5%. Stimulation of the thoracic ganglia (T2-4) resulted in a 1.2 +/- 0.4% decrease in coronary vessel diameter. RIV failed to respond to bilateral caudal cervical ganglion stimulation. After iv administration of phentolamine, 1-2 mg/kg, no response to sympathetic stimulation could be elicited. Therefore, it appears that alpha-receptors are activated by the release of the sympathetic neurotransmitter to sympathetic stimulation and that beta-receptors are not involved in the response of RIV to sympathetic stimulation.

Animals↗
PubMed2006

Totally endoscopic coronary artery bypass surgery.

Robotically enhanced surgery is a fast-developing technique that allows totally endoscopic cardiac surgery on both the beating and arrested heart. Between December 2002 and May 2005, 13 patients underwent totally endoscopic coronary bypass using the da Vinci system; 11 operations were on a beating heart and 2 on arrested hearts. The mean time for internal mammary artery mobilization was 42 min. The time for left internal mammary artery-to-left anterior descending artery anastomosis was 20-36 min for totally endoscopic cases. In one patient, the right internal mammary artery was anastomosed to the diagonal artery. No patient required conversion to a median sternotomy. Mean intensive care unit stay was 1.2 days and mean hospital stay was 4.5 days. There was no hospital mortality. All 13 patients had coronary angiography at 3-month intervals, which showed 100% patency in 12 patients while one had 50% anastomotic narrowing for which coronary angioplasty was performed. Using robotic technology, completely endoscopic anastomosis is possible in patients with single-vessel disease. Use of robotics is now extended to achieve complete myocardial revascularization by harvesting both internal mammary arteries in addition to making a small thoracotomy for direct anastomosis.

Adult↗
PubMed1999

Minimally invasive port-access coronary artery bypass grafting.

The Port-Access endovascular cardiopulmonary bypass system (Heartport, Inc., Redwood City, CA, USA), a recent technological innovation in minimally invasive cardiac surgery, was conducted successfully in coronary artery bypass grafting on a 69-year-old woman. The left internal thoracic artery was harvested through a limited left anterior thoracotomy and anastomosed to the left anterior descending coronary artery on a protected and arrested heart. Intraoperative coronary angiography confirmed good graft patency. The patient was discharged from the hospital in good condition 7 days after the operation. This was the first successful minimally invasive Port-Access coronary artery bypass grafting in Japan.

Aged↗
PubMed1990

Direct effects of myocardial depressant drugs on coronary vascular tone: anesthetic vasodilation by halothane and isoflurane.

Because certain vasoactive drugs also possess negative myocardial inotropic properties, it is difficult to determine their direct pharmacological actions on coronary resistance vessels in situ. Thus, a drug's myocardial effects may induce indirect physiological changes in coronary vascular tone that confound measuring its direct action. To separate the direct from indirect drug actions on vascular tone, the authors describe an experimental system utilizing the isolated perfused rat heart arrested with tetrodotoxin. The direct effects of the volatile anesthetics halothane and isoflurane on coronary vascular tone were examined in this preparation, using the concept of minimum alveolar concentration as the measure of potency. Both anesthetics demonstrated a dose-dependent direct coronary vasodilation that was reversible, with the median effective dose being 1.31 +/- 0.08 (mean +/- S.E.) for halothane, and 1.53 +/- 0.12 for isoflurane (P = 0.06; units of measure are the fraction of minimum alveolar concentration for each anesthetic). Further studies indicated that maximal vasodilation by adenosine was diminished after 90 min of perfusion, independent of anesthetic administration. Myocardial oxygen consumption was decreased significantly from the beating state by arrest, but neither anesthetic nor adenosine affected myocardial oxygen consumption further. These data indicate that halothane and isoflurane are equipotent for inducing direct dilation of coronary resistance vessels in the isolated perfused arrested rat heart.

Adenosine↗
PubMed1986

Accelerated myocardial metabolic recovery with terminal warm blood cardioplegia.

Although blood cardioplegia provides excellent protection, myocardial metabolic recovery is delayed. To evaluate the benefits of a terminal warm cardioplegic infusion after cold blood cardioplegia, we performed a prospective randomized trial in 20 patients undergoing elective coronary bypass grafting. Eleven patients received cold blood cardioplegia and nine patients received cold blood cardioplegia and warm blood cardioplegia before cross-clamp removal (hot shot). The hot shot provided oxygen and removed excess lactate from the arrested heart. After the hot shot lactate was extracted by the heart and tissue adenosine triphosphate and glycogen concentrations were preserved. Atrial pacing and volume loading 3 and 4 hours postoperatively decreased myocardial lactate extraction after cold blood cardioplegia but increased lactate extraction after the hot shot. Left atrial pressures were higher at similar end-diastolic volumes (by nuclear ventriculography), which suggested decreased diastolic compliance after cold blood cardioplegia. Terminal warm blood cardioplegia accelerated myocardial metabolic recovery, preserved high-energy phosphates, improved the metabolic response to postoperative hemodynamic stresses, and reduced left atrial pressures.

Adenosine Triphosphate↗
PubMed1980

[A new technique for the application of stimulating electrodes in emergencies].

The epigastric-epicardial method is taken from the puncture technique of the pericardium and always leads to effective actions of pacemakers. The method makes possible rapid approach, is to be performed in circulatory standstill, is little stressing for the patient also during longer periods of stimulation and leads to a stable position of the electrodes. At the arrested heart it is clearly superior to the deposition technique. The pacemakers used should poses a sufficient initial tension. For a regular position of the electrode speak beating of the heart against the canule, lead of a cardiac ECG and effective actions. The method is suitable for the secure care of patients who need a pacemaker, also awake patients, during longer periods and transport ways and may be recommended at first for inpatients. Which other possibilities, but also complications are included in the method, is reserved to further experiences.

Adult↗
PubMed1995

[Clinical study on the ideal temperature of blood cardioplegic solution in coronary artery bypass graft surgery].

The effect of myocardial protection in coronary artery bypass graft surgery was evaluated from enzymatic examination and cardiac function to clarify the ideal temperature of blood cardioplegic perfusate (BCP). The surgical cases were divided into two groups from the temperature of BCP; 8 degrees C BCP in 64 cases (Group I) and 20 degrees C BCP in 64 cases (Group II). Peak total creatine-Kinase (CK) and CK-MB fraction were significantly elevated in Group I than in Group II. The value of CK-MB was 79 +/- 79 IU/L in Group I and 37 +/- 26 IU/L in Group II (p < 0.01). The parameters of cardiac function were measured from radio-isotope (RI) ventriculography in the 35 cases with depressed ejection fraction and elevated left ventricular end-diastolic pressure (17 cases in Group I and 18 cases in Group II). Postoperative parameters such as ejection fraction, first third ejection fraction, peak ejection rate and early diastolic peak filling rate improved more significantly than preoperative values in Group II, although these parameters did not improve in Group I. From these results, 20 degrees C BCP provided excellent myocardial protection to arrested heart during coronary artery bypass surgery probably because of decreased viscosity of BCP and adequate oxygen carrying capacity to myocardium.

Blood↗
PubMed1994

New trends in the pharmacologic management of cardiac arrest.

In recent years a number of trends in the pharmacologic management of cardiac arrest have developed. Interventions that should be considered, especially for patients with refractory ventricular fibrillation, are high-dose epinephrine and additional antifibrillatory therapies, such as amiodarone and magnesium sulfate. Other advances in the management of refractory ventricular fibrillation include an improved understanding of the mechanism of action of epinephrine and other pressor agents in the arrested heart, and refined indications and recommendations for the use of sodium bicarbonate, lidocaine, bretylium and beta-blocking agents.

Epinephrine↗
PubMed1993

Recovery of postischemic contractile function is depressed by antegrade warm continuous blood cardioplegia.

To assess the effectiveness of warm antegrade continuous blood cardioplegia in the setting of an acute coronary arterial occlusion, we instrumented 19 Yorkshire swine to quantitate left ventricular global, systolic, diastolic, and regional mechanics. Data were acquired before and after 10 minutes of mid-left anterior descending coronary artery occlusion followed by 60 minutes of aortic crossclamping. Cardiac arrest was induced by the antegrade infusion of 20 ml/kg of warm (37 degrees C) or cold (4 degrees C) oxygenated blood cardioplegic solution followed by either continuous warm (75 ml/min, n = 9) or intermittent cold (10 ml/kg every 20 minutes, n = 10) cardioplegic reinfusions. Left anterior descending coronary artery occlusion was released 20 minutes after aortic crossclamping and resulted in warm-arrested hearts developing a 139% increase in global oxygen consumption compared with values obtained with the left anterior descending coronary artery occluded (p < 0.02). Recovery of global left ventricle contractility, quantitated by the linear preload recruitable stroke-work relationship, was significantly worse after warm cardioplegia (52.4% +/- 5.1% versus 68.0% +/- 5.9%, warm versus cold, p < 0.05). Similarly, left anterior descending coronary artery regional ischemic zone contractility recovered 34.5% +/- 7.3% of control function with cold cardioplegia, whereas warm cardioplegia resulted in -11.36% +/- 7.46% functional recovery indicative of dyssynchronous contraction (p < 0.05). Diastolic compliance, calculated with an exponential end-diastolic pressure-versus-volume relationship, was not changed postischemically in either group. These data suggest that warm antegrade blood cardioplegia may potentiate acute ischemic injury and provide inadequate myocardial protection.

Animals↗
PubMed1975

[Active exchange of Na and K in perfused and procaine arrested rat heart].

Recovery of normal Na and K contents of perfused and procaine arrested rat ventricules occurs with a rate constant of 0.109 mn-1 (i.e. 60% of restoration is achieved in 7.5 mn) after a 45 mn arrest of active transport produced by perfusion with a K free Krebs-Henseleit solution. Active Na efflux is nearly equal to K influx. Peak Na Efflux is estimated to be 11.2 muEq.g-1dry.mn-1 or 19.7 pM.cm-2.s-1, i.e. more than 4 times leakage flux of the resting heart. Na efflux is not proportional to Na intracellular concentration but to the square of this concentration.

Animals↗
PubMed1994

Increased intracranial pressure and cardiac arrest after heart transplantation. What about the Cushing response in a denervated heart? Case report.

A 13-year-old boy suffered cerebrovascular complications after heart transplantation (ischemic mass effect in the posterior cranial fossa). He had to be resuscitated from cardiac arrest with coma. After a modified cerebellar hemispherectomy the course was favorable.--The most conclusive explanation for the acute event is that a Cushing response was preserved even in the presumably denervated heart.

Adolescent↗
PubMed1998

Myocardial metabolism studied during warm blood antero-retrograde reperfusion in ischaemic human hearts.

We propose modified warm blood antegrade-retrograde reperfusion (WBARR) of arrested hearts as a metabolic model with which to study substrate exchange and energy metabolism during the recovery phase after 90 min of ischaemia in man. Eleven anaesthetized patients undergoing aorto-coronary bypass were studied during WBARR. The protocol was designed as follows: period 1, a warm blood reperfusion with potassium (3 min); period 2, a warm blood reperfusion without potassium (2 min). The perfusion flow rate averaged 250+/-2 ml/min at the beginning of period 1 and 218+/-19 ml/min at the beginning and at the end of period 2; the perfusion was performed antegradely and retrogradely in the arrested hearts. Samples were simultaneously taken from the coronary venous sinus (CVS) and from the aortic root needle (AR). At the beginning of WBARR lactate release was 85+/-44 micromol/min and at the end it had significantly decreased to 21+/-99 micromol/min (P<0.03). Simultaneously, non-esterified fatty acids (NEFA) and beta-hydroxy-butyrate were initially released (71+/-61 and 22+/-66 micromol/min, respectively), while at the end of the WBARR there was an uptake of both NEFA (20+/-22 micromol/min; P<0.01) and beta-hydroxy-butyrate (12+/-35 micromol/min; P=0.290). Alanine, glycerol and branched chain amino acid balance across the heart did not significantly change. In summary after 90 min of ischaemia the heart energy metabolism is mainly anaerobic and based on glucose consumption, with lactate, NEFA and amino acids, which are mainly released. After 5 min of WBARR (recovery from ischaemia), lactate release is significantly reduced and NEFA becomes the energy supply of the heart. In conclusion, (1) WBARR is a valuable method with which to study myocardial metabolism in anaesthetized humans and may be combined with the use of tracers; (2) the study of myocardial metabolism in arrested hearts eliminates the imprecisions arising from the noncontinuous coronary blood flow; (3) NEFA become an important source of energy utilized by human hearts in the recovery phase from ischaemia.

Adult↗
PubMed1991

Diastolic coronary resistance and capacitance are independent of the duration of diastole.

Systolic myocardial contraction may produce changes in coronary resistance and capacitance that persist throughout a normal diastole. In addition, coronary resistance and capacitance as determined in the arrested heart may not accurately describe normal diastolic behavior. To evaluate these possibilities, an identification method capable of characterizing the input impedance of the coronary circulation in as little as 150 ms was developed. Using this method, coronary dynamics were measured during early and late diastoles in the beating heart with tone intact as well as during adenosine-induced maximal vasodilation. Coronary dynamics were also measured in the arrested heart during maximal vasodilation. With vasomotor tone intact, the parameters of a lumped model of the coronary circulation showed no variation from early to late diastole. During maximal vasodilation, model parameters also showed no variation from early to late diastole. Parameters in the arrested heart were not statistically different from those of the beating heart during maximal vasodilation. However, model parameters determined during maximal vasodilation were significantly different from those determined with tone intact. These results suggest that although coronary resistance and capacitance are dependent on vasomotor tone, they remain constant throughout diastole and remain similar in the arrested heart.

Animals↗
PubMed1992

Ultrastructural alterations of the conduction system in mice exhibiting sinus arrest or heart block during Coxsackievirus B3 acute myocarditis.

By light and electron microscopy we studied the sinus nodes and atrioventricular (AV) conducting tissue of six C3H/He mice having coxsackievirus B3 acute myocarditis. Sinus arrest was documented in all six mice, and second- or third-degree AV block was documented in three of the six mice. Although myocarditic changes in the conduction system, especially in the sinus node, were less than those in atrial and ventricular working myocardium, there were distinct abnormalities within both the sinus node and AV conducting tissue in all six hearts. Important ultrastructural alterations were inflammatory cell infiltrates and significant injury of specialized cells and of neural tissue. Specialized cells showed various features of degeneration and necrosis. Neural tissue damage included degeneration of axons and Schwann cells and disorganization of the neuromuscular junctions. Inflammatory cells, particularly macrophages, were often in intimate contact with injured specialized cells and neural tissue. Interstitial edema and bleeding and lymphatic vessel dilatation were also observed. These pathologic changes are considered to play an important role in the development of the documented disturbances of rhythm and conduction.

Animals↗