Treatment of PAT. Bradycardiac reflexes induced by dive vs. body-tilt.

It has been suggested that the dive reflex (elicited by face immersion in water with breath-hold) may be employed to induce vagally-mediated bradycardia in individuals with paroxysmal atrial tachycardia. However, in several cases the use of this reflex is reported to have led to exacerbation of the cardiac dysfunction. Examination of heart-rate and EKG T-wave amplitude changes during the dive in healthy, college-aged individuals indicated that warming the water (10 degrees through 20 degrees C to 40 degrees C) decreased the bradycardia, but did not alter the attenuation (approximately 100 mu v) of the T-wave. The latter effect was taken to indicate that sympathetic activity, as indexed by T-wave amplitude, was not reduced by increases in water temperature. On the other hand, a 90 degrees head-up to head-down body tilt produced a bradycardia response of some 30 bpm as well as a T-wave amplitude increase (sympathetic withdrawal) in the order of 100 mu v. These data suggest that individuals who exhibit symptoms of ventricular sympathetic irritability may be adversely affected by the dive maneuver, regardless of water temperature. The body-tilt induced reflex in such individuals may thus be more appropriate given the large-magnitude bradycardia and absence of T-wave attenuation. At the present, however, the body-tilt preparation has been used only with healthy normal subjects, so this suggestion remains to be directly tested.

Propranolol medication among coronary patients: relationship to type A behavior and cardiovascular response.

The present correlational study compared behavioral and psychophysiological characteristics of coronary patients who were either medicated or not medicated with the beta-adrenergic blocking drug propranolol. Eighty-eight patients were given a structured Type A interview (SI) and a history quiz while heart rate and blood pressure were monitored. Data were analyzed controlling for age, sex, extent of coronary artery disease, and history of angina. Results indicated that patients taking propranolol (n = 65) were significantly lower in intensity of Type A behavior than patients not taking propranolol (n = 23). No effects were obtained for patients medicated or not medicated with diuretics, nitrates, or other CNS active drugs. Propranolol patients also showed lesser heart rate and rate-pressure product responses to the interview, but did not differ in blood pressure responses. Components of Type A which were lower in propranolol patients included speech stylistics (loud/explosive, rapid/accelerated, potential for hostility). Content of responses to the SI and scores on the Jenkins Activity Survey did not differ between the groups. An explanation for these results is offered in terms of the effects of propranolol on peripheral sympathetic responses, and evidence for a physiological substrate for Type A behavior. A conceptualization of the Type A pattern in terms of cognitive and physiological components is advanced, and implications for clinical intervention are discussed.

Type A behavior and coronary artery bypass surgery: intraoperative blood pressure and perioperative complications.

Previous research has suggested that Type A, compared to Type B patients undergoing coronary artery bypass surgery evidence greater intraoperative increases over hospital admission systolic blood pressure, even though patients are under general anesthesia. The present study sought to examine whether such blood pressure increases are accounted for by elevations occurring entirely during surgery (with conscious mediation minimized), or by increases occurring prior to surgery. A second purpose of the study was to examine the relationship between Type A behavior and complications occurring during and after surgery. Twenty-seven male patients given a structured interview to measure Type A behavior in advance of surgery comprised the present sample. Results indicated that interview Type A intensity was reliably related to magnitude of systolic, but not diastolic blood pressure increases during, but not prior to surgery. The 12 patients with complications (largely arrhythmias), were reliably higher in rated intensity of Type A behavior (p less than 0.01) than those without complications (n = 14). None of the Type B or Type X patients showed evidence of complications during or after surgery. Results of this study support a body of data linking Type A behavior to cardiovascular reactivity and clinical complications of coronary disease. Since this reactivity is evident under general anesthesia, these data further suggest that conscious mediation may not always be necessary in order to elicit these responses.

Direct and continuous measurement of relational learning in human Pavlovian conditioning.

Three experiments were conducted employing a continuous measure of conditional stimulus/unconditional stimulus (CS/US) contingencies as perceived by the subject (i.e., subjective contingency or SC). It is argues that direct measurement of relational learning, as indexed by SC, can lead to a better understanding of Pavlovian conditioning processes. The first two experiments applied this approach to a methodologic controversy, raising the debate from a procedure-based argument to testing what the subject actually learns about CS/US relationships. While the issue was not resolved, testable hypotheses for future research were generated from the data. The third experiment contrasted the contingency stimulus-stimulus (S-S) account of Pavlovian conditioning with an earlier stimulus-response (S-R) contiguity-reinforcement account. In this experiment, both SC and skin resistance were measured. Evidence for the existence of both cognitive-propositional and response-learning processes in conditioning was obtained.