Circadian variations of blood pressure and heart rate early and late after heart transplantation

Circadian rhythms in solid organ transplantation

Circadian rhythms are daily cycles in physiology that can affect medical interventions. This review considers how these rhythms may relate to solid organ transplantation. It begins by summarizing the mechanism for circadian rhythm generation known as the molecular clock, and basic research connecting the clock to biological activities germane to organ acceptance. Next follows a review of clinical evidence relating time of day to adverse transplantation outcomes. The concluding section discusses knowledge gaps and practical areas where applying circadian biology might improve transplantation success.

Predictive value of achieved blood pressure for cardiac events in the long-term follow-up of heart transplant recipients

BACKGROUND

A low diastolic blood pressure (DBP) is associated with increased cardiovascular events in patients with coronary artery disease or chronic kidney disease.

AIM

The aim of this study was to assess the association of blood pressure with cardiac events during the long-term follow-up of heart transplant recipients.

PATIENTS AND METHODS

In this prospective cohort study, we performed ambulatory blood pressure monitoring and home blood pressure monitoring in 76 transplant heart recipients 13.5±6.6 years after transplantation. The patients were followed for 54±17 months after blood pressure monitoring.

RESULTS

Twenty-one patients had a cardiac event (cardiac death, acute coronary event, coronary revascularization procedure, and hospitalization for heart failure) during the follow-up. In the Kaplan-Meier survival analysis, we found that a DBP below the median value (<81 mmHg) was associated significantly with cardiac events (log-rank: P=0.01). In a multivariate model, plasma creatinine and left ventricular ejection fraction (LVEF), but not DBP, were associated significantly with cardiac events. Low DBP was associated significantly with LVEF less than 55% (P=0.004).

CONCLUSION

A DBP below the median value predicts cardiac events during the long-term follow-up of heart transplant recipients, but is not an independent predictor. The association between low DBP and low LVEF explains at least in part the predictive value of low DBP.

Hypertension and arterial stiffness in heart transplantation patients

OBJECTIVES

Post-transplantation hypertension is prevalent and is associated with increased cardiovascular morbidity and subsequent graft dysfunction. The present study aimed to identify the factors associated with arterial stiffness as measured by the ambulatory arterial stiffness index.

METHODS

The current study used a prospective, observational, analytical design to evaluate a group of adult heart transplantation patients. Arterial stiffness was obtained by monitoring ambulatory blood pressure and using the ambulatory arterial stiffness index as the surrogate outcome. Multivariate logistic regression analyses were performed to control confounding.

RESULTS

In a group of 85 adult heart transplantation patients, hypertension was independently associated with arterial stiffness (OR 4.98, CI 95% 1.06-23.4) as well as systolic and diastolic blood pressure averages and nighttime descent.

CONCLUSIONS

Measurement of ambulatory arterial stiffness index is a new, non-invasive method that is easy to perform, may contribute to better defining arterial stiffness prognosis and is associated with hypertension.

Comparison of office, home, and ambulatory blood pressure in heart transplant recipients

BACKGROUND

The purpose of this study was to prospectively evaluate the relationship between office, home, and ambulatory blood pressure (BP) in heart transplant recipients.

METHODS AND RESULTS

The study enrolled 30 adults ≥ 6 months after heart transplantation. Morning seated office BP was measured with the use of an automatic device at 3 outpatient visits. Seated home BP was measured in the morning and evening for 5 consecutive days. Ambulatory BP was measured over 24 hours with the use of a Spacelabs monitor. The strongest correlation was observed between home and 24-hour ambulatory BP (r = 0.79 systolic; r = 0.72 diastolic). Office and home systolic BPs were significantly lower than daytime ambulatory BP (office, -3.7 mm Hg, P = .009; home, -2.6 mm Hg, P = .05). Ambulatory monitoring identified more participants with BP above hypertensive limits than did office or home measurements (63%, 50%, and 13%, respectively; P = .003). Ambulatory monitoring also revealed high BP loads, abnormal nocturnal BP patterns (eg, 30% nondippers), and a high percentage of masked hypertension (37% home, 50% ambulatory).

CONCLUSIONS

Office and home BP monitoring are acceptable but may underestimate BP burden in heart transplant recipients. Additional studies are needed to determine which BP method is superior for the management of hypertension and associated outcomes after heart transplantation.

Home blood pressure monitoring in heart transplant recipients: comparison with ambulatory blood pressure monitoring

BACKGROUND

How reliable is home blood pressure monitoring (HBPM) in heart transplant recipients is not known. Possibly, it may underestimate hypertensive burden, because blood pressure (BP) nondipper profile is frequent among these patients. This prospective study has been designed to determine whether HBPM adequately identifies hypertension in heart transplant recipients.

METHOD

We compared HBPM with ambulatory blood pressure monitoring (ABPM) for the diagnosis of uncontrolled hypertension in 74 patients 13.5±6.7 years after heart transplantation. HBPM was measured with a validated semiautomatic device twice every morning and twice every evening on 7 consecutive days, within 15 days of ABPM. We also measured the relationship between HBPM, ABPM, and organ damage as measured by albuminuria and left ventricular mass.

RESULTS

A nondipper profile was found in 53 (72%) patients. HBPM and ABPM were close according to Pearson bivariate correlations. There was no significant correlation between left ventricular mass and BP either at HBPM or ABPM. Proteinuria significantly correlated with systolic BP either at HBPM (R=0.42; P=0.0002) or ABPM (R=0.25; P=0.03). HBPM adequately classified 61 of 74 (82%) patients as hypertensives or as nonhypertensives or controlled hypertensives.

CONCLUSION

Despite a high prevalence of nondipper profile, HBPM gives a reliable estimate of BP burden in most heart transplant recipients. Thus, our results strongly suggest that HBPM is useful for the long-term follow-up of heart transplant recipients.

The Importance of 24 Hour Ambulatory Blood Pressure Monitoring After Thoracic Organ Transplantation

BACKGROUND

Hypertension is a significant complication after thoracic organ transplantation. In the non-transplant population, 24-hour ambulatory blood pressure monitoring (24ABPM) is useful in the diagnosis of white-coat hypertension, the assessment of resistant hypertension, and the monitoring of anti-hypertensive therapy. The loss of nocturnal reductions in blood pressure is associated with hypertensive end-organ damage. This study investigated the role of 24ABPM after orthotopic cardiac transplantation.

METHODS

Thirty-three transplant recipients underwent 24ABPM. Clinical blood pressure (CPB) was measured by using a sphygmomanometer before 24ABPM. Clinical data were collected and analyzed by a single observer with p values of less than 0.05 being taken as significant.

RESULTS

The incidence of hypertension (diastolic pressure > 90 mm Hg) in the CPB and 24ABPM groups was 33% and 52% (p =0.002). Thirty-two percent of recipients who were normotensive by clinical measurement were found to be hypertensive after 24ABPM. The converse was true in 1 case. We identified no specific risk factors for 24ABPM hypertension. One recipient failed to complete the 24-hour monitoring period.

CONCLUSION

This study demonstrates that conventional blood pressure monitoring underestimates the incidence of post-transplantation hypertension. Twenty-four hour ambulatory blood pressure monitoring is well tolerated and may improve the management of post-transplantation hypertension. White-coat hypertension is an uncommon diagnosis after cardiac transplantation, and those recipients who are hypertensive in the clinic setting should be considered true hypertensives.

The loss of circadian heart rate variations in patients undergoing mitral valve replacement and Corridor procedure--comparison to heart transplant patients

We have presently demonstrated that when added to mitral valve replacement (MVR) the corridor procedure is 75% efficient in restoring and maintaining sinus rhythm in patients with chronic atrial fibrillation (AF), caused by rheumatic mitral valve disease, (follow up 13.9months). In the same patient population, we observed that the typical day-night cycle heart rate (HR) variations were lost and our present study concentrates on this subject. Heart rate variability analysis based on 24-h Holter ECG recording (StrataScan 563 DelMar Avionics) or hospital discharge (12th-14th postoperative days) was performed in 3 patient groups: Group I: Patients with a Corridor procedure added to MVR (12pts, m/f 10/2, mean age 47.3+/-7.5yr); Group II (control): with patients MVR performed through the left atrial approach, without additional antiarrhythmic procedures (10pts, m/f 3/7 mean age 51.5+/-6.7yr), and Group III: heart transplant recipients (5pts, mean age 46.4+/-11.22yr). We analyzed the hourly heart rate over 24-h period divided into three 8-h segments (07-14h; 15-22h and 23-06h). Statistical comparison of mean hourly heart rate values was made between the three time periods of Holter monitoring. The Corridor procedure performed with mitral valve replacement resulted in conversion of sinus rhythm in 75% of patients (Group I), but postoperative heart rate variability analyses based on Holter monitoring disclosed that the mean heart rate was not statistically significantly difficult between the three 8-h segments of the day-night (P>0.05). The same results were found in the group of patients after heart transplant (P>0.05). The same results were found in the group of patients after heart transplant (P>0.05). In the second group (classical MVR), statistically significant differences in mean HR variation existed between the three 8-h intervals (P<0.05), and although atrial fibrillation occurred postoperatively physiologic circadian heart rate variations were preserved. With the Corridor procedure, both atria were surgically and electrically isolated and chronotropic function of the ventricles was restored by creating a small strip of atrial tissue with isolated sinus node and atrio-ventricular node, connected to the ventricles. This technique produced heart denervation nervous system influence, producing the loss of circadian HR variations, similar to the transplanted heart.