Complete heart block as the sole presentation of Lyme disease.

We report a case of Lyme myocarditis presenting solely as complete heart block in a previously healthy 32-year-old white man. Indium cardiac antimyosin scan showed diffuse uptake (2+, on a scale of 0 to 4+) during the acute phase of the illness. The electrocardiogram and the indium cardiac antimyosin scan were normal 6 weeks after completion of tetracycline and prednisone treatment. Lyme carditis should be considered in the differential diagnosis of complete heart block of unclear origins, even in patients presenting without other signs or symptoms suggestive of Lyme disease.

Thallium kinetics in rat cardiac transplant rejection.

Cardiac transplant rejection is a very complex process involving both cellular and vascular injury. Recently, thallium imaging has been used to assess acute transplant rejection. It has been suggested that changes in thallium kinetics might be a sensitive indicator of transplant rejection. Accordingly, thallium kinetics were assessed in vivo in acute untreated rat heterotopic (cervical) transplant rejection. Male Lewis rats weighing 225-250 g received heterotopic heart transplants from syngeneic Lewis rats (group A; n = 13), or allogeneic Brown Norway rats (group B; n = 11). Rats were imaged serially on the 2nd and the 7th postoperative days. Serial cardiac thallium content was determined utilizing data collected every 150 sec for 2 hr. The data were fit to a monoexponential curve and the decay rate constant (/sec) derived. By day 7 all group B hearts had histological evidence of severe acute rejection, and demonstrated decreased global contraction. Group A hearts showed normal histology and contractility. However, thallium uptakes and washout of the two groups were the same. Peak thallium uptake of group B was +/- 3758 1166 counts compared with 3553 +/- 950 counts in the control group A (P = 0.6395); The 2-hr percentage of washout was 12.1 +/- 1.04 compared with 12.1 +/- 9.3 (P = 1.0000); and the decay constant was -0.00002065 +/- 0.00001799 compared with -0.00002202 +/- 0.00001508 (P = 0.8409). These data indicate that in vivo global thallium kinetics are preserved during mild-to-severe acute transplant rejection. These findings suggest that the complex cellular and extracellular processes of acute rejection limit the usefulness of thallium kinetics in the detection of acute transplant rejection.

Silent versus symptomatic ischemia during a thallium-201 exercise test.

One hundred thirty-four patients with redistribution on a thallium-201 exercise test who did not experience angina (group 1) were compared with 134 patients also having redistribution who had angina during the test (group 2). The groups were matched by age, sex, and peak exercise heart rate. Although patients in both groups achieved an equivalent exercise level, patients in group 1 had less frequent (53 vs 71%, p less than 0.005) and less severe (0.15 +/- 0.13 vs 0.20 +/- 0.13 mV, p less than 0.005) ischemic ST-segment depression. Group 1 also had less ischemic thallium-201 images in terms of the number of redistributing defects, the severity of the worst redistributing defect, and an ischemic index composite of both extent and severity. Patients in group 1 were less likely to undergo early revascularization (12 vs 29%, p less than 0.005), but in the remaining patients the occurrence of adverse cardiac events was similar (21% vs 29%, p = not significant). By multivariate analysis, only the ischemic index correlated with early revascularization in group 1 (p = 0.0017), whereas the percent maximal predicted heart rate correlated best in group 2 (p = 0.0003). In group 1 the ratio of lung/heart thallium-201 uptake correlated best with an outcome of nonfatal myocardial infarction or cardiac death (p = 0.0024); in group 2 the presence of fixed left ventricular dilatation did (p = 0.0022). Thus, patients with exercise-induced thallium-201 redistribution without angina have less ischemia than patients experiencing angina.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of predischarge low-level exercise thallium testing after thrombolytic treatment of acute myocardial infarction.

Low-level exercise thallium testing is useful in identifying the high-risk patient after acute myocardial infarction (AMI). To determine whether this use also applies to patients after thrombolytic treatment of AMI, 64 patients who underwent early thrombolytic therapy for AMI and 107 patients without acute intervention were evaluated. The ability of both the electrocardiogram and thallium tests to predict future events was compared in both groups. After a mean follow-up of 374 days, there were 25 and 32% of cardiac events in the 2 groups, respectively, with versus without acute intervention. These included death, another AMI, coronary artery bypass grafting or angioplasty with 75% of the events occurring in the 3 months after the first infarction. The only significant predictors of outcome were left ventricular cavity dilatation in the intervention group and ST-segment depression and increased lung uptake in the nonintervention group. The sensitivity of exercise thallium was 55% in the intervention group and 81% in the nonintervention group (p less than 0.05). Therefore, in patients having thrombolytic therapy for AMI, nearly half the events after discharge are not predicted by predischarge low-level exercise thallium testing. The relatively weak correlation of outcome with unmasking ischemia in the laboratory before discharge may be due to an unstable coronary lesion or rapid progression of disease after the test. Tests considered useful for prognostication after AMI may not necessarily have a similar value if there has been an acute intervention, such as thrombolytic therapy.

Medically refractory unstable angina pectoris. I. Long-term follow-up of patients undergoing intraaortic balloon counterpulsation and operation.

Of 82 patients with medically refractory unstable angina pectoris seen between October 1972 and January 1978, 60 patients underwent a combination of intraaortic balloon pump counterpulsation, cardiac catheterization and coronary revascularization. Most patients had atherosclerotic involvement of the vessels of the anterior left ventricular wall, 48 patients (80 percent) had abnormalities of left ventricular wall contraction and 22 patients (36 percent) had evidence of acute myocardial injury. One operative and one late death occurred. The perioperative infarction rate was 5 percent. Survivors, followed up for 3 to 63 months (mean 31 months), have done remarkably well; 77 percent are considered employable,and more than 90 percent are in functional class I or II.

Effects of perfusion pressure on myocardial performance, metabolism, wall thickness, and compliance: comparison of the beating and fibrillating heart.

The effects of brief periods of graded reductions in perfusion pressure on normally beating and fibrillating hearts were examined. Mechanical and metabolic parameters were studied in the isolated, isovolumic (balloon in left ventricle), blood-perfused dog heart preparation. Experiments were carried out at perfusion pressures of 100, 75, 50, and 25 mm Hg, and comparisons of performance were made at the same ventricular volumes in the beating and fibrillating heart. A fall in perfusion pressure significantly decreased systolic performance in the beating heart. Diastolic pressure-volume relations were not altered by changes in perfusion pressure in the beating heart, but the fibrillating heart became significantly more compliant as perfusion pressure declined. Coronary blood flow and myocardial oxygen consumption were consistently higher during fibrillation than during sinus rhythm, and both parameters declined significantly at decreasing perfusion pressures. The fibrillating heart produced lactate at a perfusion pressure below 65 mm Hg, while the beating heart produced lactate at a perfusion pressure below 35 mm Hg. These studies demonstrate that brief periods of relatively modest decreases in perfusion pressure during ventricular fibrillation alter myocardial energy demand-supply relationships to result in ischemia of the fibrillating heart.

Hemodynamic effects and oxygen transport properties of a new blood substitute in a model of massive blood replacement.

Recent concerns regarding the safety of the national blood supply have rekindled interest in the development of blood substitutes. Clinical studies have dampened the initial enthusiasm for fluorocarbon solutions as blood substitutes. The potential of hemoglobin solutions as blood substitutes has continued to stimulate investigations. However, the development of an ideal hemoglobin-derived blood substitute has eluded investigators for the past century. A persistent problem has been the inability to develop hemoglobin solutions that provide adequate oxygen and carbon dioxide exchange, while avoiding toxicity that precludes clinical safety and long-term survival. Traditionally, investigators have focused on human hemoglobin solutions. The use of outdated banked blood or pedigree human donor blood as a hemoglobin source poses continued disease transmission risks and a prohibitively limited supply. We evaluated the hemodynamic and gas transport effects of a new purified, polymerized bovine hemoglobin preparation. Bovine hemoglobin oxygen affinity is regulated by chloride ion. The concentration of chloride ions in human plasma results in excellent oxygen transport properties in a stroma-free environment. In addition, unlike human blood, bovine blood is a more disease-free hemoglobin source that is available in large supply. We exchange-transfused eight conscious sheep with this new polymerized bovine hemoglobin solution. All animals tolerated greater than or equal to 95% exchange transfusion to reach a final ovine hematocrit of 2.4 +/- 0.5% with stable hemodynamics and no clinical evidence of distress. The exchange transfusion with bovine hemoglobin polymer resulted in a final plasma hemoglobin concentration of 6.1 +/- 1.6 gm/dl, which supported oxygen consumption at baseline levels. All animals that were exchange transfused with this preparation survived long term with rapid resynthesis of ovine erythrocytes.

Cyanosis in uncomplicated atrial septal defect with normal right cardiac and pulmonary arterial pressures.

A patient with cyanosis in an uncomplicated ostium secundum atrial septal defect without pulmonary hypertension is described. There were no anatomic abnormalities in right-sided cardiac valves or venous return and no evidence of right ventricular hypoplasia or hypertrophy; however, the diastolic pressure curve suggested a decreased compliance. We suggest that this unusual finding may be a result of intrinsically abnormal right ventricular compliance.

Cardiac prostacyclin kinetics during cardiopulmonary bypass.

We have investigated the response of systemic and myocardial prostacyclin metabolism to cardiopulmonary bypass and 30 minutes of hypothermic (22 degrees C), hyperkalemic (25 mEq K+) surgical cardioplegia. Thirteen adult mongrel dogs of either sex (range 21 to 36 kg) underwent sterile cardiopulmonary bypass without donor blood. Prostacyclin levels were obtained after cannulation, 20 minutes after onset of partial bypass, and 5 seconds after the onset of cardioplegia 1 (CP-1) and cardioplegia 2 (CP-2, 30 minutes later). Samples were drawn from the thoracic aorta, the aortic root below cross-clamping, and the coronary sinus. The stable metabolite of prostacyclin, 6-keto-PGF1 alpha was measured by double-antibody radioimmunoassay (pg/ml; values +/- standard error of the mean). We found that the onset of partial bypass is associated with significant increase in the systemic production of 6-keto-PGF1 alpha (122 +/- 33 versus 518 +/- 187; p less than 0.05), which persists throughout the experiment. A small but significant positive cardiac gradient of 6-keto-PGF1 alpha is found after cannulation (aortic root 122 +/- 33, coronary sinus 202 +/- 57, p less than 0.05). This gradient is more pronounced during partial bypass (aortic root 518 +/- 187, coronary sinus 686 +/- 186 p less than 0.05), when significant cardiac lactate extraction (p less than 0.005) is observed. After cross-clamping, a significantly increased gradient of 6-keto-PGF1 alpha is found during CP-1 (aortic root 74 +/- 10, coronary sinus 264 +/- 46, p less than 0.05 versus cannulation) in the presence of significant cardiac lactate production (p less than 0.005). A further significant increase in 6-keto-PGF1 alpha production is noted during the CP-2 infusion (aortic root 73 +/- 10, coronary sinus 483 +/- 83; p less than 0.01 versus CP-1), which is inversely related to cardiac oxygen uptake and endocardial/epicardial flow ratio. Our data demonstrate significant production of prostacyclin in the systemic and cardiac circulations during cardiopulmonary bypass and surgical cardioplegia. They further indicate that both ischemic and nonischemic stimuli regulate prostacyclin metabolism during cardiopulmonary bypass.

Prostaglandin E1. A new therapy for refractory right heart failure and pulmonary hypertension after mitral valve replacement.

Patients undergoing mitral valve replacement, particularly those with severe pulmonary hypertension and/or congestive heart failure, may develop life-threatening right heart failure in the immediate postbypass period. We have observed that such patients have intense pulmonary vasoconstriction. The markedly increased pulmonary impedance may aggravate the right heart failure and prevent recovery of right ventricular function in this setting. Therefore, we studied the effects of high-dose prostaglandin E1 (30 to 150 ng/kg/min), a potent pulmonary vasodilator, in combination with massive infusion of norepinephrine (up to 1 microgram/kg/min) into the left atrium in five consecutive patients with refractory right heart failure and pulmonary hypertension after mitral valve replacement. This pharmacologic approach takes advantage of the pulmonary vasodilating effects of prostaglandin E1, while offsetting associated systemic vasodilation and resulting hypotension. All five patients had rapid pulmonary vasodilator responses followed by marked improvement in right ventricular function. All survived the operation and none had right ventricular infarction or chronic right heart failure postoperatively.

Effect of experimental cardiopulmonary bypass on systemic and transcardiac thromboxane B2 levels.

Systemic and cardiac metabolism of thromboxane was studied in a canine model (n = 13) of standard cardiopulmonary bypass and surgical cardioplegia. Sterile techniques were applied and no donor blood was used. Systemic samples (thoracic aorta) and transcardiac gradients (coronary sinus - aortic root) were obtained (1) 5 minutes after cannulation, (2) 20 minutes after the onset of partial bypass, (3) 5 seconds after the first administration of cardioplegic solution (CP-1), and (4) 5 seconds after the second administration of cardioplegic solution (CP-2). Cardioplegic doses were administered 30 minutes apart and consisted of 500 ml of hypothermic (8 degrees C), hyperkalemic (25 mEq potassium chloride) solution infused into the aortic root at 60 to 70 mm Hg. Thromboxane B2 was determined by a double-antibody radioimmunoassay (picograms per milliliter +/- standard error of the mean). Onset of partial bypass was followed by a significant rise in systemic arterial thromboxane B2 levels: after cannulation, 115 +/- 21 pg/ml; after the onset of partial bypass, 596 +/- 141 pg/ml; p less than 0.01). Significant transcardiac thromboxane B2 gradients were found during the first and second cardioplegic washouts (CP-1: aortic root 73 +/- 12 pg/ml, coronary sinus 306 +/- 86 pg/ml, p less than 0.01; CP-2: aortic root 65 +/- 11 pg/ml, coronary sinus 355 +/- 98 pg/ml, p less than 0.01). Transcardiac gradients of 6-keto-prostaglandin F1 alpha and thromboxane B2 were obtained at CP-1 and CP-2. Gradients of 6-keto-prostaglandin F1 alpha were not different from thromboxane B2 gradients during CP-1 but were significantly higher than thromboxane B2 gradients during CP-2. In a subgroup of five dogs, transcardiac thromboxane B2, lactate, and platelet gradients were measured simultaneously. Cardiac thromboxane B2 generation was found only in the presence of cardiac lactate production. Transcardiac platelet gradients were significantly higher at CP-1 (13,900 +/- 3,000/mm3) than at CP-2 (4,000 +/- 1,230/mm3) (p less than 0.05), whereas thromboxane B2 gradients were similar at CP-1 and CP-2. Our study demonstrates that thromboxane B2 is released into the coronary circulation during surgical cardioplegic arrest with anaerobiosis.

Effect of angiographic contrast agents on the mechanical performance of the isolated rat papillary muscle preparations.

The effects of the radiographic contrast agents Renografin, Isopaque, and Hypaque on the mechanical performance of isometrically contracting rat papillary muscle was compared to a new contrast agent, Amipaque. It was found that exposure to Amipaque resulted in significantly less depression of contractile activity than any of the other agents. Changes in mechanical performance associated with exposure to Renografin, Isopaque, or Hypaque could not be attributed to either hypocalcemia or hypoxia. The decrease in developed tension and increase in resting tension was similar to that produced by Krebs-Henseleit containing hypertonic (1420 mmol) glucose or sucrose. Thus, the data support the concept that hyperosmolarity of the radiographic contrast agents may be primarily responsible for the adverse effects on mechanical performance of the myocardium associated with angiography.

Local relation between oxidative metabolism and perfusion in leg muscles of patients with heart failure studied by magnetic resonance imaging and spectroscopy.

BACKGROUND: We studied the local relation of muscle perfusion and metabolism in patients with severe chronic heart failure. Alterations of skeletal muscle blood flow and oxidative capacity contribute to exercise intolerance in these patients. The interdependence of both parameters has often been questioned. METHODS AND RESULTS: With the use of nuclear magnetic resonance, we quantified leg and muscle perfusion during reactive hyperemia in 7 patients with heart failure (New York Heart Association class III and IV) and 7 age-matched control subjects from the difference in longitudinal relaxation rate (1/T1). By using 31P nuclear magnetic resonance spectroscopy, we assessed oxidative metabolism from the creatine rephosphorylation time constant after a short ischemic exercise. Phosphocreatine recovery is slowed (74.6 +/- 11.3 vs 49.9 +/- 13.9 seconds, p = .002) and reactive hyperemic flow is reduced (48.5 +/- 24.9 vs 113 +/- 30.4 mL/100 mL per minute, p = .0005). CONCLUSIONS: By using a totally noninvasive protocol, we demonstrated that reactive hyperemic flow correlates with oxidative capacity in calf muscles from patients with heart failure, showing that exercise performance and local circulatory dysfunction are decreased in parallel in severe heart failure.

Determinants of maximal right ventricular function.

After heart transplantation, right ventricular failure can occur because of increased afterload. Previous studies have suggested that the maximal pressure the right ventricle can develop is determined primarily by right ventricular perfusion pressure. However, the interaction of the left ventricle and the pericardium as functional co-determinants of maximal right ventricular function is unknown. This study was undertaken to determine the interaction of the pericardium, left ventricular pressure, and right coronary artery perfusion pressure as potential determinants of maximal right ventricular function. In an acute canine preparation, with progressive pulmonary artery constriction, maximal generated right ventricular pressure was determined over a range of left ventricular systolic pressures. Additional groups of dogs were studied with the right coronary artery cannulated and were maintained at constant perfusion pressure. In all preparations, the maximal pressure the right ventricle could generate was linearly related to left ventricular systolic pressure. Having a closed pericardium markedly enhanced this effect; some effect was present with an open pericardium, although the magnitude of the influence of left ventricular pressure on maximal right ventricular pressure was much less. Maintaining constancy of right coronary artery perfusion pressure, either at high or low values, did not alter these findings nor did it alter the influence of the pericardium. These results suggest that right ventricular perfusion may not be the sole determinant of maximal right ventricular function. Furthermore, with the pericardium open, such as in the posttransplantation state, the left ventricular contribution to maximal right ventricular function may be diminished, increasing vulnerability for right ventricular failure caused by increased afterload.

Hemoglobin blood substitutes in extended preoperative autologous blood donation: an experimental study.

BACKGROUND: The risks of homologous blood transfusion have stimulated interest in developing possible alternatives. In this study we examined the efficacy of using a hemoglobin-derived blood substitute to augment and extend preoperative autologous blood donation. METHODS: In an ovine model, two experimental groups (n = 6 each) of animals donated either 45% or 80% or more of calculated blood volume, which was replaced with a polymerized bovine hemoglobin solution. Two control groups (n = 6 each) either did not donate or donated 45% of calculated blood volume, which was replaced with a 6% hetastarch solution. Twenty-four hours after blood donation, sheep underwent a measured surgical stress with standardized intraoperative blood loss; donated blood was reinfused. RESULTS: Extended autologous blood donation and replacement with this blood substitute were efficacious in supporting oxygen consumption; there was no systemic toxicity. After the postoperative replacement of autologous blood, animals that donated 80% or more of red cell mass exhibited overall blood conservation with a final hematocrit of 25.7% +/- 3.6%, compared with 20.5% +/- 2.0% (p < 0.05) and with 21.5% +/- 1.1% (p < 0.05) in both control groups. CONCLUSIONS: This study suggests that the benefits of a blood substitute can be combined with autologous blood donation to (1) safely increase the amount of autologous blood donated while supporting oxygen consumption, (2) avoid the need for advanced preoperative donation, and (3) decrease the need for homologous blood transfusion.

Interrelationship of oxidative metabolism and local perfusion demonstrated by NMR in human skeletal muscle.

Using nuclear magnetic resonance (NMR), we have examined the relationship of high-energy phosphate metabolism and perfusion in human soleus and gastrocnemius muscles. With 31P-NMR spectroscopy, we monitored phosphocreatine (PCr) decay and recovery in eight normal volunteers and four heart failure patients performing ischemic plantar flexion. By using echo-planar imaging, perfusion was independently measured by a local [inversion-recovery (T1-flow)] and a regional technique (NMR-plethysmography). After correction for its pH dependence, PCr recovery time constant is 27.5 +/- 8.0 s in normal volunteers, with mean flow 118 +/- 75 (soleus and gastrocnemius T1-flow) and 30.2 +/- 9.7 ml.100 ml-1.min-1 (NMR-plethysmography-flow). We demonstrate a positive correlation between PCr time constant and local perfusion given by y = 50 - 0.15x (r2 = 0.68, P = 0.01) for the 8 normal subjects, and y = 64 - 0.24x (r2 = 0.83, P = 0.0001) for the 12 subjects recruited in the study. Regional perfusion techniques also show a significant but weaker correlation. Using this totally noninvasive method, we conclude that aerobic ATP resynthesis is related to the magnitude of perfusion, i.e., O2 availability, and demonstrate that magnetic resonance imaging and magnetic resonance spectroscopy together can accurately assess muscle functional status.

Microvascular capillaroscopic abnormalities in rheumatoid arthritis patients.

Microvascular circulation was investigated by nailfold capillaroscopy in 32 patients affected by rheumatoid arthritis (RA). In all the patients elongated and tiny capillaries as well as tortuousity were the main shape abnormalities of the capillary loops. Higher subpapilar venous plexus (SPVP) visibility was evidentiated in patients presenting antinuclear and anti-RANA antibodies. No differences in the capillaroscopic pattern were found between rheumatoid factor positive and rheumatoid factor negative patients. In conclusion, elongated and tortuous capillaries seem to be the main alterations in RA, although they are not specific to the disease and are not correlated with the presence of rheumatoid factor. Higher SPVP visibility may be an expression of the endothelial damage induced by antinuclear antibodies in vessel walls.