Hyperparathyroidism with Wenckebach's phenomenon∗

Cardiac conduction in patients with hypercalcaemia due to primary hyperparathyroidism

“…This was unexpected since hypercalcaemia, in experiments, has been reported to be associated with an increased excitability and decreased refractoriness in combination with a slowing of conduction in the sinus and atrioventricular nodes (Watanabe, 1981). Furthermore, case reports have indicated that patients with hypercalcaemia due to hyperparathyroidism may exhibit various types of conduction disturbances (Cassagnes et al Voss & Drake, 1967;Crum & Till, 1960;Ginsberg & Schwarz, 1973;Santo et al, 1982;Baumgartl, 1975;Lischer, 1965). When grading these case reports with respect to the degree of hypercalcaemia, the severity of the conduction disorder seems to be correlated with the degree of hypercalcaemia (Table 3).…”

“…Surprisingly, clinical observations of conduction disturbances caused by hypercalcaemia are scarce. Although single case reports (Cassagnes et a Voss & Drake, 1967;Crum & Till, 1960;Ginsberg & Schwarz, 1973;Santo et al, 1982;Baumgartl, 1975;Lischer, 1965) describing patients with bradyarrhythmias including atrioventricular nodal conduction defects, sinus node disease and atrial fibrillation have been described, the prevalence of these disturbances is unknown.…”

Sick sinus syndrome secondary to primary hyperparathyroidism

“…But the major change is the shortening of Q-T interval caused by the effect of high serum calcium concentration on the plateau of the action potential of cardiac fibers. Varing degrees of atrioventricular blocks may occur, but complete heart block is rarer [4][5][6][7] . A thorough literature research revealed only two cases that showed hyperparathyroidism causing sinus node dysfunction which required pacemaker implantation 6 .…”

“…There are only few reports in the literature on hyperparathroidism-associated hypercalcemia leading to clinically significant bradyarrhythmias [3][4][5][6] .…”

“…Typical electrocardiographic changes of hypercalcemia, including hypercalcemia of hyperparathroidism, include prolongation of the P-R interval, shortenning of Q-T interval, and broad flattening of the apex of the T wave, bradycardia 1,2 . There are only few reports in the literature on hyperparathroidism-associated hypercalcemia leading to clinically significant bradyarrhythmias [3][4][5][6] .…”