Impedance cardiography revisited.

UNLABELLED: Previously reported comparisons between cardiac output (CO) results in patients with cardiac conditions measured by thoracic impedance cardiography (TIC) versus thermodilution (TD) reveal upper and lower limits of agreement with two standard deviations (2SD) of approximately +/-2.2 l min(-1), a 44% disparity between the two technologies. We show here that if the electrodes are placed on one wrist and on a contralateral ankle instead of on the chest, a configuration designated as regional impedance cardiography (RIC), the 2SD limit of agreement between RIC and TD is +/-1.0 l min(-1), approximately 20% disparity between the two methods. To compare the performances of the TIC and RIC algorithms, the raw data of peripheral impedance changes yielded by RIC in 43 cardiac patients were used here for software processing and calculating the CO with the TIC algorithm. The 2SD between the TIC and TD was +/-1.7 l min(-1), and after annexing the correcting factors of the RIC formula to the TIC formula, the disparity between TIC and TD further declined to +/-1.25 l min(-1). CONCLUSIONS: (1) in cardiac conditions, the RIC technology is twice as accurate as TIC; (2) the advantage of RIC is the use of peripheral rather than thoracic impedance signals, supported by correcting factors.

Aortico-left ventricular tunnel: collective review.

Aortico-left ventricular tunnel (ALVT) is an extremely rare congenital entity in which an abnormal communication between the aorta and the left ventricle bypasses the aortic valve. The condition usually results in gross aortic regurgitation, rapid cardiac decompensation, and death. An additional case of ALVT managed by successful surgical repair is described. The 38 cases reported in the literature are reviewed with emphasis on the clinical and pathological features, diagnosis, natural history, and management. Early operation is recommended to prevent distortion of the aortic valve, dilatation of the left ventricle, and distortion of the aortic anulus.

Retrograde embolization of a detached polyethylene catheter.

The increasing use of intravenous polyethylene catheters has led to a growing incidence of accidental breakage of catheters and migration to the heart. In this communication, we describe a patient in whom the broken fragment of catheter migrated retrogradely from the subclavian vein to the inferior vena cava and left iliac vein. The possible mechanism for such retrograde migration is postulated.

Repeated mitral valve replacement in the growing child with congenital mitral valve disease.

The successful second-replacement of mitral valve prostheses in two children, age 5 and 9 years, is reported. In one, a parachute mitral valve deformity was first corrected at the age of 10 months by the small-size 00 Starr-Edwards prosthesis. The second child had mitral valve disease caused by Marfan's syndrome 1; the valve was initially replaced at the age of 3 years by a size 0 Starr-Edwards prosthesis. For both patients, in the period between the two interventions, the left ventricle had grown in size and the mitral anulus was not a limiting factor in the insertion of a larger prosthesis of the Björk-Shiley type. Follow-up periods of 1 and 6 years, respectively, confirm excellent clinical results. Problems concerning valve replacements in pediatric patients are discussed.

The parachute mitral valve complex. Case report and review of the literature.

A 10-month-old infant, the youngest patient thus far reported to have undergone successful correction of the developmental complex known as "parachute mitral valve," is presented. Severe mitral incompetence and aortic coarctation led to recurrent cardiac failure. Both anomalies were corrected in a one-stage procedure wherein the coarctation was resected under normothermia and the mitral valve replaced thereafter by a prosthesis employing deep hypothermia and total circulatory arrest. He made an uneventful recovery. Forty-two reported cases in the literature are reviewed and the pathologic and clinical features, diagnosis, natural history, and management briefly summarized.

Rapid percutaneous tracheostomy.

We describe a new method of performing percutaneous tracheostomy rapidly and safely using a specialized instrument kit. The technique permits the safe insertion of a full-sized 7.0 (ID) or 7.5 mm (ID) cuffed cannula into the trachea within 1-2 min, through the membranous second intercartilagenous space. Animal studies have demonstrated a superior healing process compared to that seen after conventional tracheostomy techniques.

Chronic obstructive pulmonary disease in patients undergoing coronary artery bypass grafting.

The purpose of this study was to evaluate the effect of chronic obstructive pulmonary disease on patients undergoing coronary artery bypass grafting. Between June 1991 and June 1993, 651 patients underwent coronary artery bypass grafting: 37 patients (group I) had significant chronic obstructive pulmonary disease. These patients were compared with 37 matched control subjects (group II). Comparison of the groups was made with regard to postoperative morbidity and mortality. Quality of life of survivors was compared at the last follow-up. More patients in group I had preoperative arrhythmias (8 versus 1, p = 0.014). Group I patients had lower values of forced expiratory volume in 1 second (1.366 +/- 0.032 L versus 2.335 +/- 0.49 L, p < 0.0001), lower oxygen tension (63.5 +/- 8.2 versus 79.1 +/- 13.4 mm Hg, p = 0.001), and higher carbon dioxide tension (44.8 +/- 6.5 mm Hg versus 39.7 +/- 3.6 mm Hg, p = 0.001). After operation patients in group I had a longer hospital stay (8.1 +/- 3.6 days versus 6.6 +/- 1.7 days, p = 0.0236) and longer intensive care unit stay (2.64 +/- 0.9 days versus 1.23 +/- 0.49 days, p = 0.0001). More patients in group I required prolonged intubation (7 versus 1, p = 0.0278) and reintubation (5 versus 1, p = 0.088). More patients in group I had significant arrhythmias (27 versus 9, p < 0.0001). During a 16-month follow-up period, five patients in group I died, whereas none in group II died (p = 0.0271). Four deaths were related to arrhythmias. More group I patients were not functionally improved by the operation (17 versus 3, p = 0.0056). The results of coronary artery bypass grafting in patients with significant chronic obstructive pulmonary disease were not favorable in midterm follow-up. A major cause for morbidity and mortality was postoperative arrhythmias.

Morbid results of prolonged intubation after coronary artery bypass surgery.

OBJECTIVES: This study evaluated the morbid results of prolonged intubation after coronary artery bypass grafting (CABG). METHODS: Over 30 months, 66 of 1,112 patients undergoing CABG required prolonged intubation. They were matched with 66 patients who did not require prolonged intubation. Preoperative and operative variables were evaluated to determine which would predict prolonged intubation. The postoperative courses were then compared to evaluate the effect of prolonged intubation. The study population was divided into three groups: those who underwent early extubation, but required reintubation (n = 24); those who required initial prolonged intubation, but no reintubation (n = 22); and those who required initial prolonged intubation and reintubation (n = 20). RESULTS: Univariate analysis revealed unstable angina (p = 0.037), elevated creatinine (p = 0.001), reduced FEV(1) (p = 0.019), longer cardiopulmonary bypass time (p = 0.009), and a greater positive fluid balance at 24 h (p = 0.0001) as predictors of postoperative prolonged intubation. Multivariate regression analysis revealed elevated creatinine (p = 0.011), FEV(1) (p = 0.022), and fluid balance (p = 0.001) as predictors of prolonged intubation. The study population had longer ICU and hospital stays (p = 0.0001), with more infectious complications (p = 0.0001) and higher mortality (p = 0. 001). In the subgroups of the study population, patients not requiring reintubation had shorter ICU (p = 0.001) and hospital stays (p = 0.0001), fewer infectious complications (p = 0.0001), and reduced mortality (p = 0.0001). CONCLUSIONS: Patients undergoing CABG with reduced FEV(1), renal failure, and positive fluid balance 24 h postoperatively are at risk for prolonged intubation. Prolonged intubation results in significant acute and midterm morbidity and mortality. Early extubation followed by reintubation further increases morbidity and mortality rates in these patients.

Assessment of sternal vascularity with single photon emission computed tomography after harvesting of the internal thoracic artery.

OBJECTIVE: This study prospectively evaluates the effect on sternal vascularity of harvesting the left internal thoracic artery. METHODS: Twenty-four consecutive patients undergoing primary coronary artery bypass grafting were studied. One patient's procedure was altered during the operation, and he was eliminated from the study. The patients were prospectively randomized to receive a skeletonized internal thoracic artery (group I, n = 11) or a pedicled internal thoracic artery (group II, n = 12) graft. Each patient underwent a preoperative technetium 99 methylene diphosphonate bone scan using single photon emission computed tomography. The ratio of the mean counts per pixel on the left side of the sternum was compared with the mean counts per pixel on the right side. Postoperatively, all patients had a second scan, and sternal uptake was compared with the preoperative uptake. RESULTS: No significant differences in preoperative and operative variables were observed between the groups. A statistically significant reduction in blood flow to the left side of the sternum was shown postoperatively in group II compared with group I (0.61 +/- 0.11 vs 0.85 +/- 0.09; P <.001). Multivariable logistic regression analysis of preoperative and operative variables revealed only a pedicled left internal thoracic artery to be associated with a 20% or more reduction in left-to-right sternal activity ratio (odds ratio, 100; 70% confidence limits, 22-465; P =.002). CONCLUSION: A pedicled left internal thoracic artery graft to the left anterior descending artery reduces blood flow to the left side of the sternum during the acute postoperative period. This does not occur when the left internal thoracic artery is skeletonized.

Selective intracavitary and coronary hypothermic cardioplegia for myocardial preservation.Clinical, physiologic, and ultrastructural evaluation.

Intraoperative myocardial protection was evaluated in two groups of patients undergoing coronary surgery in whom different techniques for cardiac arrest were utilized. In group A, profound selective myocardial hypothermic (15 to 18 C) arrest was achieved by perfusing a coolant (7 to 10 C) into the left ventricular cavity and the coronary circulation. The average anoxic arrest time was 82.5 +/- 27 minutes. In group B, ventricular fibrillation and moderate hypothermia were used. Group A patients showed rapid physiologic recovery, low average myocardial creatinine phosphokinase (MB-CK) isoenzyme levels (7.8 IU) , and a well-preserved myocardial ultrastructure. In group B, three patients showed abnormal physiologic recovery; six patients needed postoperative inotropic support; and in seven patients, electron-microscopy revealed irreversible focal changes. The average MB-CK isoenzyme level was 85.6 IU. Analysis of our data demonstrates that when myocardial protection during coronary bypass grafting is achieved by selective profound intracavitary and coronary cooling, there is physiological, ultrastructural, and biochemical evidence of less intraoperative myocardial damage than when ventricular fibrillation is applied.

Inverted left atrial appendage presenting as a left atrial mass after cardiac surgery.

Inversion of the left atrial appendage can masquerade as a new left atrial mass. Failure to be aware of this entity can result in unnecessary diagnostic and therapeutic procedures. If the entity is diagnosed intraoperatively, treatment is simple with external reduction and ligation.

Effect of topical vasodilators on internal mammary arteries.

The internal mammary artery (IMA) is the conduit of choice for grafting the left anterior descending artery. However, arterial spasm and reduced early flow has been a cause of postoperative morbidity. The purpose of this study is to evaluate the effect of vasodilators on IMA flow. Fifty patients who had the IMA harvested in preparation for bypass grafting were studied. The IMA was mobilized from the subclavian vein to below the bifurcation of the IMA. The artery was prepared for grafting at least 3 cm proximal to the bifurcation. The IMA was allowed to bleed freely, and flow was determined (flow 1). The patients were divided into five groups: group I (n = 10) had 10 mL of saline solution applied topically to the IMA; group II had topical papaverine (5 mg/10 mL normal saline solution) applied to the IMA; group III had nitroglycerin (5 mg/10 mL normal saline solution) applied to the IMA, group IV had sodium nitroprusside (2.5 mg/10 mL) applied to the pedicle, and group V had 5 mL of papaverine mixed in 5 mL of saline solution injected into the periarterial tissues of the IMA pedicle. Before cardiopulmonary bypass, the flows were remeasured (flow 2). With each measurement, hemodynamic parameters were recorded. The time between measurements was recorded. There was no difference in blood pressure or pulse at the time of measurement.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed postoperative paraplegia complicating repair of type A dissection.

We describe the very rare event of delayed transient paraplegia after repair of type A dissection of the aorta and discuss therapeutic options. We also suggest insertion of a spinal catheter as soon as there are signs or symptoms of spinal cord injury to drain spinal fluid and maximize the effect of elevated spinal cord perfusion pressure.

Anatomic considerations in closed transatrial cannulation of the coronary sinus.

Successful closed transatrial coronary sinus cannulation is dependent on a proper catheter insertion site and proper catheter direction. Accurate anatomic landmarks are described to provide a reproducible cannulation site and catheter direction. This results in consistent successful cannulation of the coronary sinus.

Phrenic nerve injury after coronary artery bypass grafting: will it go away?

BACKGROUND: Phrenic nerve injury after coronary artery bypass grafting resolves in most cases. The purpose of this study was to analyze the causes and effects of persistent phrenic nerve injury after coronary artery bypass grafting. METHODS: From a registry of patients with chronic obstructive pulmonary disease who underwent coronary artery bypass grafting, 64 patients were identified who experienced phrenic nerve injury during their operation. Fifteen patients either died during follow-up (n = 9) or were lost to follow-up (n = 6). At the last follow-up visit, all the patients underwent an ultrasound evaluation of the diaphragm and were divided into those who had persistent dysfunction (group I) and those who had normal function (group II). The groups were compared for preoperative and operative risk factors, acute and midterm postoperative results, and quality of life at last follow-up. RESULTS: There were 13 patients in group I and 36 in group II. There were no significant differences in preoperative and operative risk factors between the groups. The length of hospitalization was similar for both groups (9.2 +/- 4.5 versus 8.5 +/- 3.3 days, respectively; p = 0.77). More patients in group I required reintubation (23% versus 14%, respectively; p = 0.04). The mean duration of follow-up was 32.7 +/- 9.2 months. At that time, both groups suffered a reduction of forced expiratory volume in 1 second compared with preoperative values. Group I had a greater reduction in forced expiratory volume in 1 second (p = 0.05). There were a total of 125 postoperative readmissions during the follow-up period, 36 in group I and 89 in group II. There were more admissions because of pulmonary problems in group I (85% versus 53%; p = 0.04). Of the 49 patients, 21 perceived a decline in quality of life after operation. More patients in group I (46% versus 22%; p = 0.05) complained of this decrease. CONCLUSIONS: A significant number of patients who incur phrenic nerve injury after coronary artery bypass grafting have persistent phrenic nerve injury. Patients with persistent phrenic nerve injury have increased acute and midterm morbidity after operation, as well as reduced quality of life.

Comparison of systemic vasodilators: effects on flow in internal mammary and radial arteries.

BACKGROUND: Spasm is a major concern with the use of arterial conduits in coronary artery bypass surgery (CABG). We evaluated the effect of systemic vasodilators on in vivo radial artery flow compared with internal mammary artery (IMA) flow. METHODS: Fifty patients undergoing primary CABG with a mean age of 69 +/- 5 years enrolled in this study and were randomized to 1 of 5 groups based on the vasodilating agent administered (nitroglycerin, nitroprusside, dobutamine, milrinone, and normal saline as control group). Radial artery and IMA flows, blood pressure, central venous pressure, and heart rate were measured before and 10 minutes after drug administration. RESULTS: Mean arterial pressure decreased significantly after drug administration in both the nitroglycerin (p = 0.007) and nitroprusside (p < 0.001) groups and increased in the dobutamine group (p < 0.001). There were no significant differences between IMA flow or radial flow among the groups before drug administration. A multivariate general linear model was created and revealed drug (specifically nitroglycerin) as the only predictor to increase flow in the IMA (p < 0.001) or the radial artery (p = 0.009). CONCLUSIONS: We conclude that intravenous nitroglycerin causes in vivo vasodilatation of both the IMA and radial artery and is a good systemic vasodilator to be given when harvesting these two conduits.

Interaction of thyroid hormone and heparin in postischemic myocardial recovery.

BACKGROUND: Triiodothyronine (T3) administration can improve postischemic myocardial recovery. Heparin can interfere with cellular binding of T3. Introduction of heparin into an isolated heart model may interfere with this effect. METHODS: Four groups of 8 rat hearts were placed on a modified Langendorff apparatus. All groups underwent 15 minutes of perfusion with modified Krebs-Henseleit solution (KH), followed by 20 minutes of normothermic global ischemia and 30 minutes of reperfusion. Group I underwent reperfusion with KH. Group II underwent reperfusion with KH and 1 x 10(-6) mol/L of T3. In group III, hearts underwent preischemic perfusion with heparinized KH (1,000 U/L) and reperfusion with KH containing 1 x 10(-6) mol/L of T3 and 1,000 U/L of heparin. In group IV, rats were given heparin at 2,000 IU/kg 30 minutes before sacrifice, and isolated hearts were reperfused with KH and 1 x 10(-6) mol/L of T3. A latex balloon in the left ventricle monitored hemodynamic variables. RESULTS: Left ventricular developed pressure throughout postischemic reperfusion was greater in all the groups receiving T3 when compared with group I. Group II showed significantly greater recovery than either group III (p < 0.05) or group IV (p < 0.05). CONCLUSIONS: Addition of T3 to the reperfusate enhances postischemic myocardial recovery in the isolated heart model, whereas addition of heparin reduces this effect.

Phrenic nerve injury after coronary artery grafting: is it always benign?

BACKGROUND: The purpose of this study was to evaluate the effect of phrenic nerve injury (PNI) occurring during coronary artery bypass grafting in patients with major chronic obstructive pulmonary disease (COPD). METHODS: Over a 42-month period, 1,303 patients underwent primary coronary artery bypass grafting. Sixty-seven (5.14%) had major COPD, and 29 (43.3%) of these 67 sustained PNI (group I). These patients were matched for age and ejection fraction with 29 CABG patients with COPD but without PNI (group II), 29 patients without COPD but with PNI (group III), and 29 patients with neither COPD nor PNI (group IV). The groups were compared on the basis of preoperative and operative factors and immediate and midterm morbidity and mortality. RESULTS: There were no significant differences between the groups with respect to hypertension, diabetes, ejection fraction, number of grafts, internal mammary artery use, cardiopulmonary bypass time, and ischemic time. Postoperatively, group I had a longer total hospitalization (group I, 11.7 days; group II, 7.8 days; group III, 7.8 days; and group IV, 6 days; p = 0.0001) and stay in the intensive care unit (I, 3.6 days; II, 2.2 days; III, 2.1 days; and IV, 1.2 days; p = 0.0023). More patients in group I required reintubation (I, 37.9%; II, 3.4%; III, 6.9%; and IV, 0%; p < 0.0001). Mean follow-up was 32.8 months (range, 7 to 48 months). Group I had more hospital readmissions (I, 78; II, 50; III, 61; and IV, 28; p < 0.007) and lower cumulative survival (I, 60.6%; II, 93%; III, 96.8%; and IV, 100%; p < 0.0015) compared with the other groups. CONCLUSIONS: In patients with COPD, PNI during coronary artery bypass grafting has a major negative impact on immediate and midterm results.

Selective intracavitary and coronary profound hypothermic cardioplegia for myocardial preservation: a new technique.

A technique is described for selective intracavitary and coronary hypothermic perfusion during cardiac bypass with cardioplegia to facilitate cardiac operations. A cold perfusate (Plasmalyte 148 and mannitol, 12.5 gm/L at 8 degrees to 10 degrees C) is administered with the aid of a low-flow perfusion pump into the left ventricular cavity and coronary circulation through an apical perfusion-venting (Per-Vent) catheter. This perfusate cools the myocardium rapidly and homogeneously to a temperature of 15 degrees to 20 degrees C. Within this temperature range, complete cardioplegia occurs and the safe ischemia period can be extended to 120 minutes. This method was applied in 50 unselected consecutive adult patients undergoing aortocoronary saphenous vein bypass grafting or aortic or mitral valve replacement. All patients survived and had excellent recovery of ventricular function.

Effect of systemic vasodilators on internal mammary flow during coronary bypass grafting.

BACKGROUND: The effect of vasodilators on acute flow in the internal mammary (IMA) is unclear. Topical vasodilators show no effect on acute flow when the distal segment of the IMA is resected. The purpose of this study was to evaluate the effect of systemic vasodilators when this segment is resected. METHODS: We studied 60 patients with proximal anterior descending coronary artery lesions in whom the left IMA was harvested for grafting to the left anterior descending coronary artery. The patients were divided into six groups (n = 10), based on which of the following agents were studied: normal saline solution, nitroglycerin, nitroprusside, dobutamine, dopexamine, and amrinone. After harvesting, the IMA was trimmed as proximally as possible (and at least 3 cm proximal to the bifurcation), and free flow was measured before any pharmacologic intervention (flow 1). Systemic infusion of one of the six agents commenced. A mean of 17 +/- 3.4 minutes after infusion began, with a comparable cardiac index, a second measurement of IMA flow was taken (flow 2). Hemodynamic measurements for each flow, including blood pressure, heart rate, and cardiac output, were taken. RESULTS: A significant increase in IMA flow was noted for those patients receiving nitroglycerin (93.5 versus 106.8 mL/min; p = 0.025), and a significant decrease in flow was noted for those receiving nitroprusside (91.0 versus 78.2 mL/min; p = 0.042). The effects remained significant when corrected for cardiac index and compared with the normal saline solution group. No other systemic agents tested significantly affected the IMA flow (dobutamine, 83.8 versus 85.0 mL/min; dopexamine, 101.8 versus 91.4 mL/min; amrinone, 75.4 versus 79 mL/min; normal saline solution, 85.8 versus 84.6 mL/min). CONCLUSIONS: Resection of the distal segment of the IMA and the use of intravenous nitroglycerin optimizes the flow in IMA grafts.