The dose-dependent effect of chronic Verapamil treatment on cardiac function in isolated rat heart with Hypertension

Funding Acknowledgements

Type of funding sources: None.

Introduction

Verapamil, a calcium channel blocker, is used for treatment of hypertension, paroxysmal supraventricular tachycardia  and angina pectoris. It primarily blocks L-type calcium channels preventing excessive influx of calcium into cardiomyocytes, leading to negative inotropic effect, and smooth muscle cells resulting in reduced relaxation of vasculature. With calcium antagonism it also causes negative chronotropic effect. However, there is no data on it’s dose-dependent effects on cardiac dynamic parameters and heart rate on isolated rat heart with hypertension.

Purpose

To investigate chronic, dose-dependent effects of Verapamil on cardiodynamic parameters in isolated rat heart with hypertension.

Methods

The present 4-week study was carried out on 24 spontaneously hypertensive Wistar Kyoto male rats  (6 weeks old): Control (n = 6), rats treated with 0.5 mg/kg/day of Verapamil (n = 6), rats treated with 5 mg/kg/day of Verapamil (n = 6) and rats treated with 50 mg/kg/day of Verapamil (n = 6). Isolated rat hearts were perfused on Langendorff perfusion apparatus.

Results

Chronic, low-dose Verapamil treatment significantly depressed function of all cardiodynamic parameters of the hypertensive heart when compared to the rats treated with higher doses of Verapamil (p < 0.001), except on the coronary flow and heart rate when compared to the Control (p= 0.137; p = 1.000, respectively). There was no significant differences between Verapamil in middle dose (5 mg/kg/day) and the Control group in inotropic (p = 0.415) and lusitropic (p = 1.000) effects, while it significantly lowered values of coronary flow (p = 0.002). It achieved significantly lower inotropic, lusitropic and chronotropic effects (p < 0.001) than high Verapamil dose and significantly better inotropic (p = 0.017), lusitropic (p < 0.001), but not chronotropic effects than low-dose Verapamil treatment (p = 0.179). High-dose, chronic treatment with Verapamil significantly intensified function of  the isolated rat heart with hypertension when compared to Control and lower doses of Verapamil (p < 0.001), without significant effects on coronary flow (p = 0.363).

Conclusions

Chronic treatment with Verapamil in high dose achieved better inotropic, chronotropic and lusitropic effects than treatment in low and middle doses of Verapamil, without significant effects on coronary flow. There is dose-depended effect of chronic Verapamil treatment on cardiac function of isolated rat heart with hypertension.

Cardiac rehabilitation and secondary prevention in COVID-19 times: Single center experience

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiac rehabilitation (CR) is a class I treatment for cardiovascular disease, still, underutilization of these services remains. During the coronavirus 2019 (COVID-19) pandemic, an even greater gap in CR care has been present.

Purpose and methods

We aimed to present the cardiac rehabilitation during COVID 19 times in Belgrade. At the beginning of epidemic in Serbia the number of patients in in-house city program was 70 out of 70 beds, with 200 patients who were scheduled (on the waiting list). Similarly to the other countries, we continued to admit only urgent patients with acute coronary settings.

Results

Only one PPCI center in Belgrade (2 million inhabitants plus surrounding area; out of five centers) continue to admit COVID-negative patients with STEMI from 13of March to 11 of May, during the first pick of COVID-19 epidemic in Serbia. Out -patients cardiac rehabilitation programs were stopped. The totals of 80 patients (PCR negative) were transferred to exercised based cardiac rehabilitation secondary prevention program during the first pick of epidemic directly from acute hospital. The majority of patients were males in their 50s. All risk factors were noted and patients were with much less risk factors compared to non- epidemic era. Lipid profile was measured. Six minutes walking test was performed at the beginning and exercise plan was made. Unfortunately, exercise based three weeks in- house cardiac rehabilitation was completed in only 1% of patients while others quite the program.

Conclusion

The COVID-19 pandemic presents a time to highlight the value of home-based models as we search for ways to continue to provide care. Standardization of home based CR models is essential to provide care for a wider range of patients and circumstances in the near future.

P561Acute effects of dronedarone and amiodarone on functional, morphological and oxidative stress parameters in isolated rat heart with hypertension

Introduction

Amiodarone represents the most widely used antiarrhythmic drug, even though it has been shown that it has negative inotropic and lusitropic effect in healthy hears. On the other hand, dronedarone reduces the risk of recurrent atrial fibrillation, but with increased early mortality related to the worsening of heart failure. However, the mechanisms responsible for these fatal outcomes remain unclear and require further examinations. 

Purpose

To investigate acute, direct effects of Dronedarone and Amiodarone on cardiac contractility, coronary flow and oxidative stress parameters in isolated rat heart with hypertension.

Methods

 The present study was carried out on 18 isolated hearts of spontaneously hypertensive Wistar Kyoto male rats (6 weeks old, bodyweight 200 ± 10 g). After isolation, all hearts were retrogradely perfused according to Langendorff technique with a gradually increment of coronary perfusion pressure (CPP from 40 to 120 cm H2O) and randomly divided into 3 groups: Control (n = 6), Amiodarone (n = 6, isolated hearts perfused with Amiodarone in dose of 3 umol), Dronedarone (n = 6, isolated hearts perfused with Dronedarone in dose of 1.8 umol). During ex vivo protocol continuously were registered cardiac contractility parameters and coronary flow, while from collected coronary venous effluent markers of oxidative stress were measured. All hearts were then fixated and stained with Hematoxylin/eosin.

Results

 Dronedarone severely depressed the function of all cardiodynamic parameters of the heart compared with Amiodarone or Control while Amiodarone intensified the function of the isolated rat heart with hypertension compared to Control (dp/dt max mmHg/s at coronary perfusion pressure 120cmH2O Dronedarone vs. Amiodarone vs. Control 579.733 ± 202.27 vs. 3063.65 ± 467.93 vs. 2682.88 ± 368.75; p < 0.001. dp/dt min mmHg/s 120cmH2O -352.13 ± 204.65 vs. 1960 ± 242.21 vs. -1858.83 ± 118.23; p < 0.001. SLVP mmHg at CPP 120cmH20 27.8 ± 3.46 vs. 98.95 ± 11.78 vs. 71.45 ± 7.56; p < 0.001. DLVP mmHg at CPP 120cmH2O 6.32 ± 0.49 vs. 4.83 ± 0.54 vs. 0.85 ± 0.35; p < 0.001). Acute administration of Dronedarone decreased the level of NO2- and increased the level of H2O2 , while Amiodarone heightens O2- levels (O2- nmol/min g wt at coronary perfusion pressure 120cmH2O Dronedarone vs. Amiodarone vs. Control  28.62 ± 2.54 vs. 77.3 ± 8.86 vs. 31.72 ± 4.56; p < 0.001. H2O2 nmol/min g wt at CPP 120cmH2O 92.56 ± 11.65 vs. 48.63 ± 10.11 vs. 42.84 ± 84; p < 0.001. NO2- nmol/min g wt at CPP 120cmH2O 38.61 ± 4.94 vs.  82.28 ± 5.76 vs.  64.71 ± 3.51; p < 0.001). Pathohistological, structural changes were observed in both, experimental groups.

Conclusions

 Acute administration of Dronedarone depresses cardiac function in isolated, working rat heart with hypertension, with decreasing the NO2- levels, increasing the level of H2O2 and enhanced structural changes when compared to Amiodarone.

P2521Exercise-Based Cardiac Rehabilitation in post myocardial infarction patients with mid-range ejection fraction

Patients and methods

Out of 2753 patients who were admitted to our three weeks in- hospital secondary prevention program – exercised based cardiac rehabilitation, we analyze a total of 219 patients who were admitted early after coronary revascularization (percutaneus coronary interventions or coronary bypass surgery) with HFmrEF. The majority of patients were males (68%). Risk factors and co morbidities were noted. Patients were selected for exercise training after six minute walking test or exercise stress test (cardiopulmonary dominantly to evaluate unexpected exertional dyspnea). After 3 weeks in house cardiac rehabilitation the patients were re-tested.

Results

The major comorbidities in our patient population were as follows: hypertension, diabetes and dyslipidemia. Six minutes walking test was performed and the total distance walked ranged from 120 to 480 meters and the beginning of the program. Patient had 7 -days a week training program. After the 3 weeks in hospital exercise rehabilitation the improvement in the test was ∼32%. Cardiopulmonary test showed also improvement of functional capacity.We noted several rhythm disturbance complications by telemetry (VES, SVES). None had acutisation of heart failure (with peripheral edema and congestion). All patients fulfilled cardiac rehabilitation program.

Conclusions

Supervised multidisciplinary cardiac rehabilitation program, including an individualized exercise component is effective and can improve functional status and exercise tolerance in patient with HFmrEF after myocardial infarction.