Orthostatic hypotension: A commonly unrecognized cause of symptoms in mitral valve prolapse

To test the hypothesis that orthostatic hypotension could represent an alternative mechanism contributing to the symptoms of mitral valve prolapse, the systolic and diastolic arterial blood pressures were measured in the supine and standing positions in 86 patients with the diagnosis confirmed by echocardiography. Orthostatic hypotension was demonstrated in 12 patients. Ten of them presented with a history of recurrent lightheadedness, dizziness or syncope and constitute 59 percent of the total number of patients with such symptoms in this series. Although nine of these 10 patients reported transient lightheadedness or dizziness during periods of ambulatory electrocardiographic recording, in only one were the symptoms chronologically related to cardiac arrhythmias. On the other hand, eight of them described lightheadedness and two experienced near-syncope during the postural test in association with the orthostatic drop in blood pressure. Improvement in symptoms and correction of the orthostatic hypotension were demonstrated in seven patients after beta-adrenergic blockade with propranolol. Before therapy, the mean systolic blood pressure dropped from 114 ± 3 mm Hg in the supine position to 78 ± 1 mm Hg upon standing (p < 0.001). In repeated postural tests performed after four weeks of treatment, the systolic blood pressure changed from 120 ± 3 mm Hg supine to 115 ± 1 mm Hg upon standing (p > 0.01).We conclude that orthostatic hypotension is a commonly unrecognized mechanism responsible for some of the symptoms of mitral valve prolapse, particularly in patients affected by recurrent lightheadedness, dizziness or syncope.     

Stability of AV conduction in sick sinus node syndrome patients with implanted atrial pacemakers

Single-chamber atrial pacing is effective in the management of sinus node dysfunction, subject to the uncertainty of long-term atrioventricular conduction. Despite the accepted observation that many patients with sinus node dysfunction also have atrioventricular conduction disease, data do not exist on the development of atrioventricular block in those patients with permanent single-chamber atrial pacing. Of 70 patients who received single-chamber atrial pacing from 1967 to 1982 (mean duration of pacing was 33 months), only two patients of 58 (3.4%) of those with sinus node dysfunction developed atrioventricular (AV) block—after 14 months in one patient and after 23 months of successful atrial pacing in the other. None of the 12 patients paced for tachyarrhythmia management developed AV block. Of the 70 patients, 37 had assessment of AV conduction by incremental atrial pacing at the time of implant and 20 patients underwent atrial pacing on the basis of surface ECG and clinical judgment. Electrophysiologic studies were conducted only in those patients being paced for control of supraventricular arrhythmias. Only 5 of the 70 patients required conversion to ventricular pacing for technical difficulties; three of these conversions occurred in the early 1970's before the advent of atrial tined or J leads; one was for irreparable lead fracture and only one occurred in a patient with a newer design atrial lead. In conclusion, progression to AV block in patients with permanent atrial pacing is uncommon; formal electrophysiologic studies are necessary mainly in patients with supraventricular arrhythmias; and in the majority of patients, AV conduction can be assessed at the time of implant. Continued improvement in atrial leads should make atrial pacing even more successful.     

Bacterial endocarditis with ruptured sinus of valsalva and aorticocardiac fistula

A case is presented of bacterial endocarditis with a ruptured sinus of Valsalva and formation of an aorticocardiac fistula from the right coronary sinus into the right atrium and right ventricle. The pathologic, clinical and surgical aspects of bacterial endocarditis complicated by a ruptured sinus of Valsalva and an aorticocardiac fistula are analyzed. This complication of bacterial endocarditis is still uncommon, but alertness to its diagnosis makes possible early and successful surgical treatment.     

Some unusual features of gouty arthritis in females

Gouty arthritis in females is relatively infrequent, although the sex ratio may be somewhat altered in different races. A positive family history is relatively prevalent among females whose onset of gout is premenopausal. In those patients with a postmenopausal onset, the incidence of diuretic-associated gout is high. The bimodal distribution of serum urate might be related to some variance of genetic transmission in female gout.Hypertension and coronary heart disease are common coexisting conditions, as is true of gouty arthritis in males. Chronic urinary tract infection dating from previous pregnancies is a frequent complication. The relative prevalence of proteinuria and diminished renal function leads to increased hyperuricemia, with a tendency to a low urinary uric acid output. This explains in part the higher incidence of extensive tophaceous deposition but lower incidence of renal calculi. Diuretics are associated with a higher urine pH, likewise, they reduce the urinary uric acid excretion. This also may contribute to the lower incidence of renal calculi.There may be some statistical support for the low fertility rate among the gouty females. Only two females became pregnant after the onset of gouty arthritis. All other pregnancies occurred before the onset of arthritis. Even then, abnormal pregnancies were relatively frequent. Some hormonal malfunction among the gouty females cannot be discounted.Both renal calculi and tophi are frequent in female gout associated with blood dyscrasias. They may manifest early, preceding the first attack of acute gouty arthritis. In both the male and female secondary gout, the primary underlying disease governs the uric acid metabolism and the clinical symptomatology of gout. The predominant role in pathogenesis is the excessive rate of uric acid production, and its disposal is governed by the different stages of the underlying disease and the treatment. Thus, secondary gout in females appears to be somewhat different from primary gout in females, but not different from secondary gout in males.     

Acquired storage pool deficiency with increased platelet-associated IgG. Report of five cases

Acquired abnormalities of platelet aggregation have been reported with increasing frequency. We studied five patients (including two with systemic lupus erythematosus and one with compensated chronic idiopathic thrombocytopenic purpura) in whom platelet aggregation responses to collagen, epinephrine and ADP are impaired; in all cases, we found that levels of platelet-associated immunoglobulin G (IgG) were increased. In all five patients substances stored in platelet-dense granules (ATP, ADP, serotonin and calcium) were diminished. The content of the alpha-granule substance, beta-thromboglobulin, was also decreased in most cases, whereas the levels of two secretable acid hydrolase enzymes (beta-glucuronidase and beta-N-acetyl glucosaminidase) were within normal limits. These findings are similar to those observed in subtypes of congenital storage pool deficiency. However, in contrast to the congenital disorder, a membrane-bound (nonsecretable) acid phosphatase was also decreased in the patients with acquired storage pool deficiency. These findings suggest that impaired platelet aggregation on an acquired basis may, in some patients, be due to immune platelet damage resulting in a distinctive type of platelet storage pool deficiency.     

Plasma lipoprotein abnormalities associated with acquired hepatic triglyceride lipase deficiency

Two enzymes, lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL), are released into human plasma after intravenous injection of heparin. LPL is the major enzyme responsible for initiating catabolism of chylomicrons and very-low-density lipoproteins (VLDL). The physiological role of HTGL is less certain. HTGL has been postulated to be an alternate enzyme to LPL in hydrolysis of triglyceride in VLDL and to be an important enzyme for removal of phospholipid from both low-density lipoproteins (LDL) and high-density lipoproteins (HDL). In this latter role, this enzyme would convert larger, lighter lipoprotein particles to smaller denser particles. HTGL deficiency has been found in severe liver disease and with a genetic deficiency of this enzyme. A unique patient is described with acquired hepatic triglyceride lipase deficiency and vitamin A intoxication. This patient developed hypercholesterolemia with an increase in both LDL and HDL. An increased proportion of lighter LDL (LDL1) and HDL (HDL2) was noted. In addition, after administration of heparin there was no shift in the distribution of apoE in plasma fractionated using a column containing 4% agarose. These findings are consistent with a postulated role of HTGL in metabolism of light LDL and HDL particles and some classes of apoE containing lipoproteins.