Differential diagnosis of cyanotic congenital heart disease

The differential diagnosis of cyanotic congenital heart disease depends on information regarding the natural history of specific malformations and clinical clues derived from the patient's history, physical examination, electrocardiogram, and chest film. Precise diagnosis is afforded by selective angiocardiography combined with cardiac catheterization measurements. Clinical and diagnostic features of some common malformations that may produce cyanosis are discussed in two groups: group 1, malformations of right-sided valves, and group 2, malformations of great vessel (arterial) origin. Illustrative angiocardiograms are presented of each of the six lesions particularly discussed: tricuspid atresia, Ebstein's malformation of the tricuspid valve, severe pulmonic stenosis with intact ventricular septum, complete transposition of the great vessels, and truncus arteriosus.     

Pathogenesis of thrombocytopenia in cyanotic congenital heart disease

Although a significant minority of patients with cyanotic congenital heart disease (CCHD) are thrombocytopenic, the pathogenesis and prevalence have not been established. This study was designed to address these 2 issues. We included 105 patients with CCHD (60 men and 45 women; aged 21 to 54 years). Systemic arterial oxygen saturations were 69% to 78%. Hematocrits were 62% to 74% with normal iron indexes. In 26 of 105 patients (25%), platelet counts were <100x10(9)/L. The diagnosis was Eisenmenger syndrome in all 26 patients with thrombocytopenia. Platelet production was determined by flow cytometric reticulated platelet counts. Megakaryocyte mass was determined indirectly by thrombopoietin levels. Disseminated intravascular coagulation was based on prothrombin time, activated partial thromboplastin time, and D-dimers. Platelet activation was determined by levels of platelet factor 4 and beta thromboglobulin. Reference ranges were derived from 20 normal acyanotic controls. A reduction in absolute reticulated platelet counts implied decreased platelet production (p<0.001). Normal thrombopoietin levels implied normal megakaryocyte mass. Normal prothrombin time, activated partial thromboplastin time, and D-dimers excluded disseminated intravascular coagulation. Normal platelet factor 4 and beta thromboglobulin indicated absent or minimal platelet activation. Twenty-five percent of the patients with CCHD were thrombocytopenic because platelet production was decreased despite normal megakaryocyte mass. We hypothesized that right-to-left shunts deliver whole megakaryocytes into the system arterial circulation, bypassing the lungs where megakaryocytic cytoplasm is fragmented into platelets, thus reducing platelet production. In conclusion, platelet counts in CCHD appear to represent a continuum beginning with low normal counts and ending with thrombocytopenia.     

Blood volume changes in cyanotic congenital heart disease

Simultaneous red cell volume and plasma volume determinations were performed in 20 patients with cyanotic congenital heart disease. Significant hypervolemia was shown to result from an increased red cell volume. Plasma volume may be reduced but usually remains within the normal range. The good correlation between the venous hematocrit and red cell volume per kilogram provides the basis for the estimation of the red cell volume from the venous hematocrit. The common clinical practice of estimating the degree of hypoxemia from the red cell volume (or hematocrit) is at best very gross due to the large variability of the red cell volume at any given level of arterial oxygen saturation in patients with cyanotic heart disease. Red cell volume and plasma volume should be independently and simultaneously measured if accurate estimates of total blood volume changes are desired. Blood volume measurements serve as an index and guide in the medical and surgical treatment of polycythemic cyanotic patients.     

Left ventricular function in cyanotic congenital heart disease

Left ventricular function was studied with quantitative biplane cinean-giocardiography in 39 preoperative and 23 postoperative patients wlth cyanotic congenital heart disease. Diagnoses included pulmonary atresia or critical pulmonary stenosis with intact ventricular septum (group 1), tricuspld atresia (group 2) and pulmonary atresia with ventricular septal defect (group 3). Preoperative patients ranged in age from 1 day to 7 years and postoperative patients from 7 weeks to 23 years. Left ventricular end-diastolic volume was increased in preoperative patients in groups 1 and 2 (132 and 136 percent of normal, respectively) but was normal in patients in group 3. Left ventricular ejection fraction was decreased to a similar extent in preoperative groups 1 to 3: 0.54, 0.55 and 0.56, respectively. After a shunt procedure left ventricular end-diastolic volume increased to 228 and 266 percent of normal in groups 1 and 2, respectively, but remained within normal limits in group 3. Left ventricular ejection fraction was normal in postoperative group 1 patients, whose ages averaged 1.8 years, but remained decreased in group 2 and 3 patients, whose ages averaged 8.1 and 5.6 years, respectively. Duration of cyanosis and degree of left ventricular dilatation appear to be important variables in regard to pump function in patients with cyanotic congenital heart disease.     

Haemostatic defects in cyanotic congenital heart disease.

An investigation of defects of the haemostatic mechanism in 41 children with cyanotic congenital heart disease concluded that such abnormalities were common and normally involved factors synthesised in the liver, that is the vitamin K dependent factors (rothrombin, factors VII and IX) and factor V. No evidence was found of activation of the coagulation or fibrinolytic systems. The defects can be explained by deficient synthesis resulting from systemic hypoxia as well as from sluggishness of the local microcirculation caused by high blood viscosity. Vitamin K parenterally had no demonstrable effect. Replacement of these factors, possibly combined with measures to improve the microcirculation, therefore, appears to be the appropriate treatment.