Postural changes and isosorbide dinitrate. A polygraphic study in patients with coronary artery disease

Area of Science:

• Cardiology
• Pharmacology
• Physiology

Background:

• Venous return is reduced by sitting, orthostatic positions, and nitrate drugs.
• Pre-ejection period (PEP) reflects myocardial contractility and preload.
• % diastole correlates with coronary perfusion in coronary artery disease (CAD) patients.

Purpose of the Study:

• To assess non-invasively the cardiovascular stress induced by postural changes and isosorbide dinitrate (IDN).
• To evaluate the effects of IDN on cardiovascular parameters in CAD patients.

Main Methods:

• Polygraphic recordings using a Thermistor Pulse Transducer in 8 male CAD patients.
• Measurement of pre-ejection period (PEP), heart rate (HR), and % diastole.
• Assessment during clinostatism, sitting, and orthostatic positions, with and without IDN.

Main Results:

• IDN in clinostatism and sitting reduced preload (longer PEP) and increased HR, without affecting % diastole.
• Orthostatic stress increased HR and PEP in controls.
• In orthostatism, IDN caused higher HR, decreased PEP, and significantly reduced % diastole.
• Reduced % diastole was attributed to adrenergic stimulation and hypotension from IDN.

Conclusions:

• Caution is advised for CAD patients on IDN experiencing postural stress due to potential decreased coronary perfusion.
• Polygraphic studies can identify individual responses to nitrates.
• Serial recordings may assess long-term responses to IDN therapy.