• 
• 

Three Part Question

[In a patient with left ventricular failure] are [buccal nitrates equivalent to a nitrate infusion] for [preload reduction]?

Clinical Scenario

You are called to see a 60 year old man who has been increasingly breathless for a week. Examination reveals him to be mildly dyspnoeic at rest with a raised JVP and bibasal creps. There is evidence of ischaemia on his ECG. The CXR shows upper lobe diversion and Kerley B lines. You wonder whether buccal suscard would be an appropriate alternative to a GTN infusion.

Search Strategy

Medline 1966-04/03 using the OVID interface.
[(exp nitrates OR nitrate.mp OR exp nitroglycerin OR nitroglycerin.mp OR exp vasodilator agents OR GTN.mp OR glyceryl trinitrate.mp OR exp isosorbide dinitrate OR Isoket.mp OR Suscard.mp) AND {(buccal.mp OR exp mouth mucosa OR exp administration, buccal) AND (exp injections, intravenous OR intravenous.mp OR IV.mp)} AND (exp heart failure, congestive OR heart failure.mp OR LVF.mp OR left ventricular failure.mp OR congestive cardiac failure.mp OR exp ventricular dysfunction, left OR exp ventricular dysfunction OR exp pulmonary oedema)] LIMIT to human AND English language.

Search Outcome

Altogether 7 papers were found, of which 5 were reviews of nitrates rather than comparative studies. The 2 remaining publications consisted of a summary report and full article relating to the same trial. the results of this trial are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Verma SP et al, 1989, UK	36 male patients with acute LVF secondary to recent MI (<10 hours) in CCU IV vs buccal vs transdermal GTN Average doses over 90 mins: IV 12.9mg, buccal 5mg, dermal 20mg	PRCT	Left heart filling pressures	All three groups reduced	Only 36 patients Different doses of buccal, IV and dermal GTN (based on previous studies) IV dose individually titrated; buccal and dermal doses predetermined
			Cardiac output	No reduction in any group
			BP	3 patients had BP falls in buccal group but with no clinical deterioration

Comment(s)

There is very limited evidence available to allow direct comparison between intravenous and buccal routes.

Clinical Bottom Line

Buccal nitrates produce an immediate reduction in preload (comparable with intravenous GTN).

References

1. Verma SP, Silke B, Reynolds GW et al. Nitrate therapy for left ventricular failure complicating acute myocardial infarction: a haemodynamic comparison of intravenous, buccal and transdermal delivery systems. J Cardiovasc Pharmacol 1989;14(5):756-762.